CN115646068A - Filter Media Containing Electrets - Google Patents

Abstract

Filtration media, such as electret-containing filtration media for filtering a gas stream (e.g., air), are described herein. In some embodiments, the filter media can be designed to have desired characteristics, such as stable filtration efficiency over the life of the filter media, increased normalized gamma, relatively low pressure drop (i.e., resistance), and/or relatively low basis weight. In certain embodiments, the filter media may be a composite of two or more types of fibrous layers, where each layer may be designed to enhance its function without substantially negatively affecting the performance of another layer of the media. For example, one layer of media may be designed to have a relatively low basis weight and/or a relatively high air permeability, and another layer of media may be designed to have a stable filtration efficiency and/or a relatively high efficiency throughout the life of the filtration media.

Description

Electret-containing filter media

This application is a divisional application of a Chinese patent application entitled "Filter Media Containing Electrets" with application number 201880025705.5, which is an international application filed on February 21, 2018 under the Patent Cooperation Treaty (PCT/ US2018/018924) entered the national phase of the national application in China, and the priority date of the application was February 21, 2017.

technical field

Embodiments of the present invention relate generally to filter media and electret-containing media, and in particular, to filter media comprising an open support layer.

Background technique

Filter elements can be used to remove contaminants in a variety of applications. Such elements may include filter media, which may be formed from a fiber web. The filter media provides a porous structure that allows fluid (eg, air) to flow through the media. Contaminant particles (eg, dust particles, soot particles) contained within the fluid may be captured on or in the filter media. Depending on the application, filter media can be engineered to have different performance characteristics.

While many types of filter media exist for filtering particulates from the air, improvements in the physical and/or performance characteristics of the filter media (eg, strength, air resistance, efficiency, and high dust holding capacity) would be beneficial.

Contents of the invention

Typically a filter medium is provided. In some cases, the subject matter of the present application is related to related products, alternative solutions to particular problems, and/or various uses of structures and compositions.

In one aspect, a filter medium is provided.

In some embodiments, a filter media includes an open support layer and a charged fibrous layer mechanically attached to the open support layer, wherein the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a first plurality of fibers comprising a second polymer. Two or more fibers, wherein the first polymer is acrylic, and wherein the open support layer is a mesh having an air permeability greater than 1100 CFM and less than or equal to 20,000 CFM.

In some embodiments, the filter media includes an open support layer and a charged fiber layer mechanically attached to the open support layer, wherein the charged fiber layer comprises a plurality of fibers having an average fiber diameter less than 15 microns and greater than or equal to 1 micron, and wherein The open support layer is a mesh with an air permeability greater than 1100 CFM and less than or equal to 20000 CFM.

In some embodiments, the filter media includes an open support layer and a charged fiber layer mechanically attached to the support layer, wherein the air permeability of the open support layer is greater than 1100 CFM and less than or equal to 20000 CFM, wherein the total basis weight of the filter media is ) greater than or equal to 12 g/m ² and less than or equal to 700 g/m ² , wherein the gamma of the filter medium is greater than or equal to 90 and less than or equal to 250, and wherein the total air permeability of the filter medium is greater than or equal to 30 CFM and less than or equal to 1100 CFM.

In some embodiments, the filter media includes a charged fiber layer, an open support layer that is mechanically attached to the charged fiber layer, and maintains the charged fiber layer in a wave-shaped configuration and maintains separation of the peaks and troughs of adjacent waves of the charged fiber layer Coarse support layer, wherein the basis weight of the charged fiber layer is less than or equal to 12g/m ² and greater than or equal to 250g/m ² , wherein the air permeability of the open support layer is greater than 1100CFM and less than or equal to 20000CFM, and wherein the total air permeability of the filter medium The rate is greater than or equal to 10CFM and less than or equal to 1000CFM.

In some embodiments, the filter media includes an open support layer having an air permeability greater than 1100 CFM and less than or equal to 20,000 CFM, adjacent to the open support layer and comprising a first plurality of fibers comprising a first polymer and a first plurality of fibers comprising a second polymer. A charged fiber layer of two plurality of fibers, an additional layer associated with the open support layer and the charged fiber layer, and a fine fiber layer associated with the additional layer, wherein the fine fiber layer comprises a plurality of electrospun fibers, and wherein the open support layer and the additional The combined air permeability of the layers is greater than 45 CFM and less than 1100 CFM.

In some embodiments, the filter media includes an open support layer having an air permeability greater than 1100 CFM and less than or equal to 20,000 CFM, adjacent to the open support layer and comprising a first plurality of fibers comprising a first polymer and a first plurality of fibers comprising a second polymer. A charged fiber layer of two plurality of fibers, an additional layer associated with the open support layer and the charged fiber layer, and a coarse support that maintains at least the charged fiber layer in a wave configuration and maintains separation of peaks and troughs of adjacent waves of the charged fiber layer layer, wherein the additional layer comprises a plurality of meltblown fibers, wherein the combined air permeability of the open support layer and the additional layer is greater than 45 CFM and less than 1100 CFM.

In some embodiments, the filter media includes an open support layer, a charged fiber layer mechanically attached to the open support layer, an additional layer associated with the open support layer and the charged fiber layer, and maintaining at least the charged fiber layer in a corrugated configuration and A coarse support layer maintaining separation of peaks and troughs of adjacent waves of a charged fibrous layer comprising a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer, wherein the open The combined air permeability of the support layer and the additional layer is greater than or equal to 45 CFM and less than 1100 CFM.

In some embodiments, the filter media includes a charged fibrous layer comprising a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer, wherein the charged fiber layer has a BET surface area of Greater than or equal to 0.35 m ² /g and less than or equal to 125,000 fibers/gram of the charged fiber layer. In certain embodiments, the filter media includes an open support layer having an air permeability greater than or equal to 500 CFM adjacent to the charged fibrous layer.

In certain embodiments, the cross-sectional shape of the first plurality of fibers and/or the second plurality of fibers is selected from the group consisting of circular, oval, dog-bone, kidney bean, ribbon, irregular, and multilobal.

In certain embodiments, the first plurality of fibers and/or the second plurality of fibers have an average largest cross-sectional dimension greater than or equal to 2 microns and less than or equal to 15 microns.

In certain embodiments, the open support layer is mechanically attached to the charged fiber layer.

In certain embodiments, the filter media is antimicrobial. In certain embodiments, the charged fibrous layer is antimicrobial. In certain embodiments, the open support layer is antimicrobial. In certain embodiments, the first plurality of fibers and/or the second plurality of fibers are antimicrobial. In certain embodiments, the filter media has a bacterial filtration efficiency of greater than or equal to 99.999%. In certain embodiments, the filter media has a virus filtration efficiency of greater than or equal to 99.999%. In certain embodiments, the first plurality of fibers and/or the second plurality of fibers comprise a bacteriostatic, fungistatic, and/or virostatic additive. In certain embodiments, the first plurality of fibers and/or the second plurality of fibers comprise a bacteriostatic, fungistatic, and/or virostatic additive. In certain embodiments, the second plurality of fibers comprises acrylic.

In certain embodiments, the BET surface area of the charged fibrous layer is greater than or equal to 0.33 m ² /g and less than or equal to 1.5 m ² /g. In certain embodiments, the BET surface area of the charged fibrous layer is greater than or equal to 0.35 m ² /g and less than or equal to 1 m ² /g.

In certain embodiments, the charged fibrous layer has less than or equal to 125,000 fibers/gram and greater than or equal to 50,000 fibers/gram. In certain embodiments, the charged fibrous layer has less than or equal to 105,000 fibers/gram and greater than or equal to 75,000 fibers/gram.

In certain embodiments, the filter media is fire resistant. In certain embodiments, the charged fiber layer is configured to remain charged after direct contact with the ignition source. In certain embodiments, the first plurality of fibers and/or the second plurality of fibers are flame resistant.

In certain embodiments, the additional layer is a meltblown layer, a spunbond layer, or a carded web layer.

In certain embodiments, the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer. In certain embodiments, the first polymer and the second polymer have different dielectric constants. In certain embodiments, the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 0.8 and less than or equal to 8. In certain embodiments, the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 1.5 and less than or equal to 5.

In certain embodiments, the second polymer comprises a synthetic material selected from the group consisting of polypropylene, dry spun acrylic, polyvinyl chloride, mod-arylic, wet spun acrylic, polytetrafluoroethylene , polypropylene, polystyrene, polysulfone, polyethersulfone, polycarbonate, nylon, polyurethane, phenolic resin, polyvinylidene fluoride, polyester, polyaramid, polyimide, polyolefin, Kevlar (Kevlar), Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, polymethylpentene, and combinations thereof. In certain embodiments, the second polymer is polypropylene.

In certain embodiments, the second polymer is present in the charged fibrous layer in an amount greater than or equal to 10 wt. % and less than or equal to 90 wt. %, relative to the total weight of the charged fibrous layer. In certain embodiments, the second polymer is present in the charged fibrous layer in an amount greater than or equal to 25 wt. % and less than or equal to 75 wt. %, relative to the total weight of the charged fibrous layer. In certain embodiments, the second polymer is present in the charged fibrous layer in an amount greater than or equal to 35 wt. % and less than or equal to 65 wt. %, relative to the total weight of the charged fibrous layer.

In certain embodiments, the first polymer comprises a synthetic material selected from the group consisting of polypropylene, dry spun acrylic, polyvinyl chloride, modified acrylic, wet spun acrylic, polytetrafluoroethylene, polypropylene, polyvinyl chloride Styrene, polysulfone, polyethersulfone, polycarbonate, nylon, polyurethane, phenolic resin, polyvinylidene fluoride, polyester, polyaramid, polyimide, polyolefin, Kevlar, Nutraceutical Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, polymethylpentene, and combinations thereof. In certain embodiments, the first polymer is a dry spun acrylic.

In certain embodiments, the first polymer is present in the charged fibrous layer in an amount greater than or equal to 10 wt. % and less than or equal to 90 wt. %, relative to the total weight of the charged fibrous layer. In certain embodiments, the first polymer is present in the charged fibrous layer in an amount greater than or equal to 25 wt. % and less than or equal to 75 wt. %, relative to the total weight of the charged fibrous layer. In certain embodiments, the first polymer is present in the charged fibrous layer in an amount greater than or equal to 35 wt. % and less than or equal to 65 wt. %, relative to the total weight of the charged fibrous layer.

In certain embodiments, the average fiber diameter of the first plurality of fibers is less than 15 microns and greater than or equal to 1 micron. In certain embodiments, the average fiber diameter of the second plurality of fibers is less than 15 microns and greater than or equal to 1 micron.

In certain embodiments, the solidity of the open support layer is less than or equal to 10% and greater than or equal to 0.1%. In certain embodiments, the solidity of the open support layer is less than or equal to 2% and greater than or equal to 0.1%.

In certain embodiments, the charged fiber layer is needle punched to the support layer. In certain embodiments, the charged fibrous layer is needled to the support layer at a perforation density of greater than or equal to 15 perforations/cm2 and less than or equal to 60 perforations/cm2. In certain embodiments, the charged fibrous layer is needled to the support layer with a needle penetration depth of greater than or equal to 8 mm and less than or equal to 20 mm.

In certain embodiments, the charged fibrous layer has a basis weight of greater than or equal to 10 g/m ² and less than or equal to 600 g/m ² . In certain embodiments, the basis weight of the open support layer is less than or equal to 200 g/m ² and greater than or equal to 2 g/m ² . In certain embodiments, the basis weight of the open support layer is less than or equal to 50 g/m ² and greater than or equal to 5 g/m ² .

In certain embodiments, the open support layer has a strand count along the first axis greater than or equal to 2 strands/inch and less than or equal to 27 strands/inch. In certain embodiments, the open support layer has a thread count along the first axis greater than or equal to 3 threads/inch and less than or equal to 20 threads/inch.

In certain embodiments, the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 2 mm. In certain embodiments, the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 10 microns. In certain embodiments, the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns. In certain embodiments, the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 500 microns and less than or equal to 2 mm.

In certain embodiments, the open support layer is formed by a spunbond process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns. In certain embodiments, the open support layer is formed by a meltblowing process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 10 microns. In certain embodiments, the open support layer is a mesh and comprises a plurality of wires having an average wire diameter greater than or equal to 500 microns and less than or equal to 2 mm.

In certain embodiments, the uncompressed thickness of the charged fibrous layer is greater than or equal to 5 mils and less than or equal to 600 mils, or greater than or equal to 30 mils and less than or equal to 350 mils.

In certain embodiments, the charged fibrous layer has an air permeability greater than or equal to 10 CFM and less than or equal to 1200 CFM. In certain embodiments, the charged fibrous layer has an air permeability greater than or equal to 80 CFM and less than or equal to 1200 CFM. In certain embodiments, the charged fibrous layer has an air permeability greater than or equal to 50 CFM and less than or equal to 650 CFM.

In certain embodiments, the overall basis weight of the filter media is greater than or equal to 12 g/m ² and less than or equal to 700 g/m ² . In certain embodiments, the overall basis weight of the filter media is greater than or equal to 25 g/m ² and less than or equal to 650 g/m ² .

In certain embodiments, the overall basis weight of the filter media is greater than or equal to 30 g/m ² and less than or equal to 800 g/m ² . In certain embodiments, the overall basis weight of the filter media is greater than or equal to 100 g/m ² and less than or equal to 450 g/m ² .

In certain embodiments, the overall thickness of the filter media is greater than or equal to 5 mils and less than or equal to 600 mils. In certain embodiments, the overall thickness of the filter media is greater than or equal to 30 mils and less than or equal to 350 mils.

In certain embodiments, the overall thickness of the filter media is greater than or equal to 100 mils and less than or equal to 4000 mils. In certain embodiments, the overall thickness of the filter media is greater than 150 mils and less than or equal to 1000 mils.

In certain embodiments, the filter media has a total air permeability of greater than or equal to 30 CFM and less than or equal to 1100 CFM. In certain embodiments, the filter media has a total air permeability of greater than or equal to 100 CFM and less than or equal to 700 CFM. In certain embodiments, the filter media has a total air permeability of greater than or equal to 10 CFM and less than or equal to 1000 CFM.

In certain embodiments, the normalized efficiency of the filter media is greater than or equal to 1 and less than or equal to 3.5.

In certain embodiments, the filter media has a dust holding capacity of greater than or equal to about 1 g/m ² and less than or equal to about 140 g/m ² . In certain embodiments, the filter media has a dust holding capacity of greater than or equal to about 80 g/m ² and less than or equal to about 140 g/m ² .

In certain embodiments, the filter media has a dust holding capacity of greater than or equal to 5 g/m ² and less than or equal to 600 g/m ² . In certain embodiments, the filter media has a dust holding capacity of greater than or equal to 200 g/m ² and less than or equal to 350 g/m ² .

In certain embodiments, the gamma of the filter media is greater than or equal to 30 and less than or equal to 250. In certain embodiments, the filter media has a gamma of 75 or greater and 150 or less. In certain embodiments, the normalized gamma of the filter media is greater than or equal to 1 and less than or equal to 10.9. In certain embodiments, the normalized gamma of the filter media is greater than or equal to 1 and less than or equal to 5.6.

In certain embodiments, the filter media has a gamma of 75 or greater and 150 or less. In certain embodiments, the gamma of the filter media is greater than or equal to 20 and less than or equal to 250.

In certain embodiments, the filter media has an initial efficiency of greater than or equal to 50% and less than or equal to 99.999%. In certain embodiments, the filter media has an initial efficiency of greater than or equal to 90% and less than or equal to 99.999%.

In certain embodiments, the periodicity of the charged fiber layer is greater than or equal to 10 waves/6 inches and less than or equal to 40 waves/6 inches. In certain embodiments, the period of the charged fiber layer is greater than or equal to 5 waves/6 inches and less than or equal to 9 waves/6 inches. In certain embodiments, the period of the charged fiber layer is greater than or equal to 3 waves/6 inches and less than or equal to 15 waves/6 inches.

In certain embodiments, filter media includes a coarse support layer. In certain embodiments, the coarse support layer comprises a plurality of fibers having an average fiber diameter greater than or equal to 8 microns and less than or equal to 85 microns. In certain embodiments, the coarse support layer comprises a plurality of fibers having an average fiber diameter greater than or equal to 12 microns and less than or equal to 60 microns. In certain embodiments, the basis weight of the coarse support layer is less than or equal to 100 g/m ² and greater than or equal to 5 g/m ² . In certain embodiments, the basis weight of the coarse support layer is less than or equal to 40 g/m ² and greater than or equal to 12 g/m ² .

In certain embodiments, the filter media includes an outer layer.

Other advantages and novel features of the invention will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying drawings. In the event that this specification and documents incorporated by reference contain conflicting and/or inconsistent disclosures, this specification shall control. If two or more documents incorporated by reference contain conflicting and/or inconsistent disclosures relative to each other, the document with the later effective date shall control.

Description of drawings

Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, which are schematic and not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated is generally represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of every embodiment of the invention labeled where illustration is not required to enable those of ordinary skill in the art to understand the invention. Shows. In the attached picture:

Figure 1A is a schematic diagram showing a cross-section of a filter media according to one set of embodiments;

FIG. 1B is a schematic diagram showing a cross-section of a filter media according to one set of embodiments;

Figure 1C is a schematic diagram showing a cross-section of a filter media according to one set of embodiments;

Figure 2A is a schematic diagram showing a cross-section of a filter media according to one set of embodiments;

Figure 2B is a schematic diagram showing a cross-section of a filter media according to one set of embodiments;

Figure 2C is a schematic diagram showing a cross-section of a filter media according to one set of embodiments;

Figure 2D is a schematic diagram showing a cross-section of a filter media according to one set of embodiments;

3 is a graph of normalized γ for exemplary filter media with and without an open support layer versus the basis weight of the charged fiber layers of the filter media, according to one set of embodiments;

4 is a graph of the normalized efficiency of exemplary filter media with and without an open support layer versus the basis weight of the charged fiber layers of the filter media, according to one set of embodiments;

5 is a graph of pressure drop (Pa) versus the basis weight of charged fiber layers for exemplary filter media with and without open support layers, according to one set of embodiments; and

6 is a graph of air resistance versus dust holding capacity for exemplary 70 g/ ^m basis weight filter media with and without an open support layer, each filter media comprising charged fibers, according to one set of embodiments.

Detailed ways

Described herein are filter media, such as electret-containing filter media for filtering a gas stream, such as air. In some embodiments, the filter media can be designed to have desirable properties, such as stable filtration efficiency, increased normalized gamma, relatively low pressure drop (i.e., resistance), and/or Relatively low fixed weight. In certain embodiments, the filter media may be a composite of two or more types of fibrous layers, where each layer may be designed to enhance its functionality without substantially negatively affecting the performance of another layer of the media . For example, one layer of media can be designed to have a relatively low basis weight and/or a relatively high air permeability, and another layer of media can be designed to have a stable filtration efficiency and/or Relatively high efficiency. The filter media described herein may be particularly useful in applications involving filtering gas streams (e.g., face masks, cabin air filtration, vacuum filtration, room filtration, furnace filtration, respirator equipment, residential or industrial HVAC filtration, HEPA ) filters, Ultra Low Specific Air (ULPA) filters, medical equipment), but the media can also be used in other applications.

In some embodiments, the filter media described herein can include an open support layer and a charged second layer (eg, a charged fiber layer). In certain embodiments described herein, the open support layer is mechanically attached (eg, needling) to the second layer. In some embodiments, the open support layer and/or the second layer may be in a corrugated configuration. In some such embodiments, the filter media can include one or more coarse support layers. In certain embodiments, the second layer is in a wave configuration, and the one or more coarse support layers maintain the second layer in the wave configuration and maintain separation of peaks and valleys of adjacent waves of the second layer. In some embodiments, one or more additional layers, such as a meltblown layer, may be associated with the open support layer. In some cases, filter media including one or more additional layers associated with an open support layer may be in a corrugated configuration.

Advantageously, in some cases, incorporation of one or more additional layers, such as meltblown layers, into the filter media described herein can increase the efficiency of the filter media compared to similar filter media without such additional layers (e.g. , initial efficiency).

In some cases, the open support layer may be positioned upstream of the charged fiber layer (eg, in a filter element) relative to the direction of gas/fluid flow. In an alternative set of embodiments, the second layer may be positioned upstream (eg, in the filter element) of the first layer relative to the direction of gas/fluid flow. Such an arrangement of layers can also stabilize the filtration efficiency of the filter medium throughout its lifetime. In some embodiments, the presence of charges in the second layer can improve the efficiency of the media relative to filter media without charges in the second layer.

Advantageously, the open support layer can have a relatively high air permeability, a relatively low basis weight, and/or a relatively high open area, thereby adding a relatively small amount of basis weight to the overall filter media (e.g., as opposed to including other support layers such as coarse Supporting layer filter media) while providing mechanical reinforcement.

In a specific set of embodiments, the second layer (e.g., charged fibrous layer) can have a relatively low number of fibers per gram of the second layer (e.g., less than or equal to 125,000 fibers/gram) and a relatively high number of fibers per unit mass. surface area (eg, greater than 0.33 m ² /g). Advantageously, such layers may exhibit increased initial efficiency, increased charge generation, and/or reduced charge dissipation compared to layers having a lower surface area per unit mass and/or a relatively high number of fibers per gram of layer Dispersion (eg, during use of layers and/or filter media comprising layers).

An example of a filter media comprising two or more layers is shown in Figure 1A. As illustratively shown in FIG. 1A , filter media 100 , shown in cross-section, may include a first layer 110 (eg, an open support layer) and a second layer 120 adjacent to first layer 110 . In some cases, first layer 110 may be directly adjacent to (ie, in direct contact with at least a portion of) second layer 120 . In alternative embodiments, the second layer 120 may be positioned upstream or downstream of the first layer 110 , but not in contact with the first layer 110 . In some embodiments, the first layer is an open support layer (eg, an open support layer with a relatively high air permeability), and the second layer is a charged fiber layer (eg, an electret layer). Other configurations are also possible. For example, as described in more detail below, in some cases the filter media includes one or more coarse support layers.

In some embodiments, an open support layer can be positioned between two layers. For example, as illustratively shown in FIG. 1B , filter media 102 shown in cross-section may include a first layer 110 (eg, an open support layer), a second layer 120 adjacent to first layer 110 , and a second layer 120 adjacent to first layer 110 . One floor 110 is adjacent to a third floor 122 . In some cases, first layer 110 may be directly adjacent to (i.e., in direct contact with at least a portion of) second layer 120 and/or third layer 122 (e.g., such that The first layer 110 is disposed between the second layer and the third layer). In alternative embodiments, the second layer 120 may be positioned upstream of but not in contact with the first layer 110 and the third layer 122 may be positioned downstream of but not in contact with the first layer 110 . In alternative embodiments, the second layer 120 may be positioned downstream of but not in contact with the first layer 110 and the third layer 122 may be positioned upstream of but not in contact with the first layer 110 . In some embodiments, the first layer is an open support layer (eg, an open support layer with a relatively high air permeability), and the second and third layers can each be charged fiber layers. In alternative embodiments, the second and third layers may be different. For example, in certain embodiments, the first layer is an open support layer, the second layer is a charged fiber layer, and the third layer is a coarse support layer. Additionally, although a coarse support layer (e.g., a third layer) is shown adjacent to the first layer in FIG. Adjacent to or disposed between the first layer and the second layer.

The terms "first layer" and "second layer" as used herein generally refer to different layers of filter media and do not necessarily imply a particular order of layers (eg, within a filter element). For example, while in some embodiments a first layer (e.g., an open support layer) may be positioned upstream of a second layer relative to the direction of fluid flow, in other embodiments the first layer may be positioned upstream relative to the direction of fluid flow. The direction of is positioned downstream of the second layer. As used herein, when a layer is referred to as being "adjacent" another layer, it can be directly adjacent to the layer, or one or more intervening layers may also be present. A layer that is "directly adjacent" to another layer means that there are no intervening layers.

In certain embodiments, a filter media can include one or more additional layers (eg, meltblown layers, spunbond layers) associated with a first layer (eg, open support layer). For example, as shown in FIG. 1C , an additional layer 130 (eg, a meltblown layer) may be associated with (eg, adjacent to) the first layer 110 . In some cases, second layer 120 is adjacent (eg, directly adjacent) to additional layer 130 . As used herein, the term "associated with" generally means in close proximity, for example, an additional layer associated with an open support layer may be adjacent to a surface. As used herein, when an (additional) layer is referred to as being associated with another layer, it may be directly adjacent to (e.g., in contact with) a surface, be applied to at least a portion of the layer, or one or more layers may also be present. Multiple intermediate components (eg, fibers, layers). An additional layer associated with another layer may have no intermediate components/layers present. In a specific set of embodiments, the additional layer is deposited on the open support layer, for example, such that the material of the additional layer coats and/or intersperses between the fibers of the open support layer. In some cases, the additional layer is a separate layer directly adjacent to the open support layer.

Based on the teachings of this specification, one of ordinary skill in the art will understand that while FIG. 1C shows three layers, there may be more than three layers. For example, in some embodiments, a filter media can include an open support layer, a first additional layer associated with the open support layer (e.g., a meltblown layer, a spunbond layer), a second additional layer associated with the first additional layer ( For example, a fine fiber layer, such as an electrospun layer), and a second layer associated with the first additional layer and/or the second additional layer. As noted above, in some embodiments, the filter media can be an electret-containing media. For example, a layer of the medium (eg, the second layer) may be charged. In general, the net charge of a layer (eg, the second layer) can be negative or positive. In some cases, at least one surface of the second layer may comprise a negatively charged material and/or a positively charged material. As described herein, in some embodiments, the polymers in the second layer (e.g., the first polymer and the second polymer) can be selected based on the polymer's dielectric constant and/or position on the triboelectric sequence . For example, in some embodiments, the second layer is formed by a carding process (eg, wherein fibers are manipulated by rollers and extensions (eg, hooks, needles)). Polymer fibers within the second layer that have significant dielectric constant differences and/or are relatively far apart in the triboelectric sequence can undergo contact charging by the carding process to produce a charged nonwoven web. A charged nonwoven web can have enhanced performance characteristics, including increased efficiency, compared to a similar nonwoven web that is not charged, all other factors being equal.

In other embodiments, a layer can be neutral (eg, have no net charge).

As described above and herein, in some embodiments, a filter media includes an open support layer having a relatively high air permeability and/or a relatively low basis weight. Non-limiting examples of suitable open support layers include meshes, scrims, and meshes. In a specific set of embodiments, the open support layer is a mesh (eg, a mesh with an air permeability greater than 1100 CFM). In another specific set of embodiments, the open support layer is a scrim (eg, a scrim with an air permeability greater than 1100 CFM). In some embodiments, the scrim is formed by a meltblown process or a spunbond process.

As described herein, an open support layer can have certain desirable characteristics, such as basis weight, solidity, and/or air permeability. For example, in some cases, the basis weight of the open support layer may be less than or equal to 200 g/m ² , less than or equal to 100 g/m ² , less than or equal to 90 g/m ² , less than or equal to 85 g/m ² , less than or equal to 80 g/m 2 /m ² , less than or equal to 70g/m ² , less than or equal to 60g/m ² , less than or equal to 50g/m ² , less than or equal to 40g/m ² , less than or equal to 30g/m ² , less than or equal to 25g/m ² , less than or equal to 10g/m ² , or less than or equal to 3g/m ² . In some embodiments, the basis weight of the open support layer (eg, mesh) can be greater than or equal to 2 g/m ² , greater than or equal to 3 g/m ² , greater than or equal to 10 g/m ² , greater than or equal to 25 g/m ² , Greater than or equal to 30g/m ² , greater than or equal to 40g/m ² , greater than or equal to 50g/m ² , greater than or equal to 60g/m ² , greater than or equal to 70g/m ² , greater than or equal to 80g/m ² , greater than 85g /m ² , greater than or equal to 90 g/m ² , greater than or equal to 100 g/m ² , or greater than or equal to 200 g/m ² . Combinations of the above mentioned ranges are also possible (eg basis weight less than or equal to 200 g/m ² and greater than or equal to 2 g/m ² , basis weight less than or equal to 50 g/m ² and greater than or equal to 5 g/m ² ). Other values of fixed weight are also possible. The fixed weight can be determined according to the test standard ASTM D-846.

In certain embodiments, the open support layer has a relatively high air permeability. For example, in some embodiments, the air permeability of the open support layer (e.g., mesh) is greater than 1,100 CFM, greater than or equal to 1,250 CFM, greater than or equal to 1,500 CFM, greater than or equal to 1,750 CFM, greater than or equal to 2,000 CFM, greater than or equal to 2,500 CFM, greater than or equal to 3,000 CFM, greater than or equal to 5,000 CFM, greater than or equal to 7,500 CFM, greater than or equal to 10,000 CFM, greater than or equal to 12,500 CFM, greater than or equal to 15,000 CFM, or greater than or equal to 17,500 CFM. In some embodiments, the air permeability of the open support layer is less than or equal to 20,000 CFM, less than or equal to 17,500 CFM, less than or equal to 15,000 CFM, less than or equal to 12,500 CFM, less than or equal to 10,000 CFM, less than or equal to 7,500 CFM, less than or equal to 5,000 CFM or less, 3,000 CFM or less, 2,500 CFM or less, 2,000 CFM or less, 1,750 CFM or less, 1,500 CFM or less, or 1,250 CFM or less. Combinations of the ranges mentioned above are also possible (eg, air permeability greater than 1,100 CFM and less than or equal to 20,000 CFM). Other values for air permeability are also possible. As determined herein, the air permeability of an open support layer is measured according to test standard ASTM D737 over a media surface area of 38 em ² and using a pressure of 125 Pa.

In a specific set of embodiments, the open support layer can be formed by a spunbond process and has a 1100CFM, air permeability greater than or equal to 1200CFM, or greater than or equal to 1300CFM. In certain embodiments, the air permeability of the open support layer may be less than or equal to 1400 CFM, less than or equal to 1300 CFM, less than or equal to 1200 CFM, less than or equal to 1100 CFM, less than or equal to 1000 CFM, less than or equal to 900 CFM, less than or equal to 800 CFM, less than or equal to Or equal to 700CFM, or less than or equal to 600CFM. Combinations of the ranges mentioned above are also possible (eg, greater than 500 CFM and less than or equal to 1400 CFM). Other ranges are also possible.

In certain embodiments, the solidity of the open support layer may be 10% or less, 8% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, or 0.5% or less. In some embodiments, the solidity of the open support layer can be greater than or equal to 0.1%, greater than or equal to 0.5%, greater than or equal to 1%, greater than or equal to 2%, greater than or equal to 3%, greater than or equal to 4%, greater than or equal to 5%, greater than or equal to 6%, or greater than or equal to 8%. Combinations of the ranges mentioned above are also possible (eg, solidity less than or equal to 10% and greater than or equal to 0.1%, less than or equal to 2% and greater than or equal to 0.1%). Other ranges are also possible. Solidity generally refers to the volume of solids as a percentage of the total volume of the layer.

In some cases, an open support layer (eg, mesh, mesh) can have a specific thread count. In some embodiments, the number of threads can be greater than or equal to 2 threads/inch, greater than or equal to 3 threads/inch, greater than or equal to 5 threads/inch, greater than or equal to 7 threads/inch, greater than or equal to 10 threads/inch threads/inch, greater than or equal to 12 threads/inch, greater than or equal to 15 threads/inch, greater than or equal to 17 threads/inch, greater than or equal to 20 threads/inch, greater than or equal to 22 threads/inch, or Greater than or equal to 25 threads/inch. In certain embodiments, the thread count may be less than or equal to 27 threads/inch, less than or equal to 25 threads/inch, less than or equal to 22 threads/inch, less than or equal to 20 threads/inch, less than or equal to 17 threads/inch Threads/inch, less than or equal to 15 threads/inch, less than or equal to 12 threads/inch, less than or equal to 10 threads/inch, less than or equal to 7 threads/inch, less than or equal to 5 threads/inch, Or less than or equal to 3 wires/inch. Combinations of the above mentioned ranges are also possible (for example, thread counts greater than or equal to 2 threads/inch and less than or equal to 27 threads/inch, greater than or equal to 3 threads/inch and less than or equal to 20 threads/inch ). Other ranges of thread counts are also possible. As used herein, thread count is measured along the first axis of the open support layer. In some embodiments, an open support layer (e.g., a mesh) can have a first number of threads on a first axis of the open support layer and a number of threads on a second axis of the open support layer that is orthogonal to the first axis. A second line with a different number of lines. The second thread count measured along the second axis of the open support layer can range as described in the context of the thread count measured along the first axis of the open support layer (e.g., the second thread count is greater than or equal to 2 threads/inch and less than or equal to 27 threads/inch, greater than or equal to 3 threads/inch and less than or equal to 20 threads/inch). As used herein, the term axis generally refers to a reference direction of a layer that is parallel to one or more lines in the layer. For example, the thread count can be determined by counting the threads per inch substantially perpendicular to a particular axis (eg, the number of threads/fibers intersecting a thread parallel to the axis).

In some embodiments, the open support layer comprises a plurality of fibers or threads. The fibers or threads of the open support layer may be continuous or discontinuous. Continuous fibers (e.g., threads) are produced by "continuous" fiber forming processes (e.g., melt blown processes, melt spinning, extrusion processes, woven yarns, laid scrims, and/or spunbond processes) and typically have longer lengths than the discontinuous fibers described in more detail below. Discontinuous fibers are, for example, staple fibers that are typically cut (eg, from filaments) or formed into discontinuous discrete fibers to have a particular length or range of lengths as described in more detail below.

In certain embodiments, the plurality of fibers or threads of the open support layer include synthetic fibers or threads (eg, synthetic polymer fibers or threads). The synthetic fibers or threads of the open support layer may be continuous fibers. Non-limiting examples of suitable synthetic fibers/threads include polyesters; polyaramides; polyimides; polyolefins (e.g., polyethylene, such as high-density polyethylene, low-density polyethylene, and/or linear low-density polyethylene) ); Ethylene-vinyl acetate; Polyacrylamide; Polylactic acid; Polypropylene; Kevlar; Nomex; Halogenated polymers (e.g., polyethylene terephthalate); Acrylics; polyphenylene ethers; polyphenylene sulfides; thermoplastic elastomers (eg, thermoplastic polyurethanes); polymethylpentenes; and combinations thereof.

Other processes and materials for forming the open support layer are also possible. For example, in some embodiments, the open support layer is a fibrous layer, an extruded layer, an oriented layer, a woven layer, or a nonwoven layer.

In certain embodiments, the adhesive is coextruded with one or more fibers/threads of the open support layer (eg, for joining the open support layer to the second layer).

In some embodiments, the plurality of fibers (or threads) in the open support layer may have an average fiber (or thread) diameter greater than or equal to 0.5 micron, greater than or equal to 1 micron, greater than or equal to 2 microns, greater than or equal to 3 microns , greater than or equal to 4 microns, greater than or equal to 5 microns, greater than or equal to 6 microns, greater than or equal to 8 microns, greater than or equal to 10 microns, greater than or equal to 15 microns, greater than or equal to 20 microns, greater than or equal to 50 microns, greater than 75 microns or more, 100 microns or more, 250 microns or more, 500 microns or more, 750 microns or more, 1 mm or more, 1.25 mm or more, 1.5 mm or more, or 1 mm or more 1.75mm. In some embodiments, the average fiber (or thread) diameter of the plurality of fibers in the open support layer can be less than or equal to 2 mm, less than or equal to 1.75 mm, less than or equal to 1.5 mm, less than or equal to 1.25 mm, less than or equal to 1 mm , less than or equal to 750 microns, less than or equal to 500 microns, less than or equal to 250 microns, less than or equal to 100 microns, less than or equal to 75 microns, less than or equal to 50 microns, less than or equal to 20 microns, less than or equal to 15 microns, less than or equal to 10 microns, less than or equal to 8 microns, less than or equal to 7 microns, less than or equal to 6 microns, less than or equal to 5 microns, less than or equal to 4 microns, less than or equal to 3 microns, less than or equal to 2 microns, or less than or equal to equal to 1 micron. Combinations of the above-mentioned ranges are also possible (for example, greater than or equal to 0.5 microns and less than or equal to 2 mm, greater than or equal to 0.5 microns and less than or equal to 10 microns, greater than or equal to 10 microns and less than or equal to 20 microns, greater than or equal to equal to 500 microns and less than or equal to 2mm). Other values for the average fiber (or wire) diameter of the open support layer are also possible. Individual fiber/wire diameters within an open support layer can be measured by microscopy such as scanning electron microscopy (SEM), and statistics about fiber/wire diameters such as average fiber/wire diameter, median fiber/wire diameter, and fiber/wire diameter The wire diameter standard deviation can be determined by performing appropriate statistical techniques on the measured fiber/wire diameters.

In an exemplary embodiment, the open support layer is formed by a spunbond process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns. In another exemplary embodiment, the open support layer is formed by a melt blowing process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 10 microns. In yet another exemplary embodiment, the open support layer is a mesh and comprises a plurality of wires having an average wire diameter greater than or equal to 500 microns and less than or equal to 2 mm.

In some embodiments, the open support layer comprises a plurality of fibers (eg, synthetic fibers, continuous fibers) (or threads) having a continuous length. In certain embodiments, the average length of the plurality of fibers (or threads) in the open support layer can be greater than about 5 inches, greater than or equal to 10 inches, greater than or equal to 25 inches, greater than or equal to 50 inches, greater than or equal to 100 inches. inches, greater than or equal to 300 inches, greater than or equal to 500 inches, greater than or equal to 700 inches, or greater than or equal to 900 inches. In some cases, the average length of the fibers (or threads) can be less than or equal to 1000 inches, less than or equal to 800 inches, less than or equal to 600 inches, less than or equal to 400 inches, or less than or equal to 100 inches. Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 50 inches and less than or equal to 1000 inches). Other ranges are also possible.

In other embodiments, the open support layer comprises a plurality of fibers (eg, synthetic fibers, staple fibers) (or threads) having an average length of less than about 5 inches (127 mm). For example, the average length of the plurality of fibers (or threads) in the open support layer can be, for example, less than or equal to 100 mm, less than or equal to 80 mm, less than or equal to 60 mm, less than or equal to 40 mm, less than or equal to 20 mm, less than or equal to 10 mm, less than or equal to Or equal to 5mm, less than or equal to 1mm, less than or equal to 0.5mm, or less than or equal to 0.1mm. In some cases, the average length of the plurality of fibers (or threads) in the open support layer may be greater than or equal to 0.02mm, greater than or equal to 0.1mm, greater than or equal to 0.5mm, greater than or equal to 1mm, greater than or equal to 5mm, greater than Or equal to 10mm, greater than or equal to 20mm, greater than or equal to 40mm, greater than or equal to 60mm. Combinations of the ranges mentioned above are possible (eg, greater than or equal to 0.02 mm and less than or equal to 80 mm, greater than or equal to 0.03 mm and less than or equal to 40 mm). Other ranges are also possible.

In some embodiments, the dry tensile strength of the open support layer is greater than or equal to 4 lbs/in, greater than or equal to 5 lbs/in, greater than or equal to 7 lbs/in, greater than or equal to 10 lbs/in, greater than or equal to 15 lbs/in, greater than or equal to 20 lbs/in or greater, 25 lbs/in or greater, 30 lbs/in or greater, 35 lbs/in or greater, 40 lbs/in or greater, 45 lbs/in or greater, 50 lbs/in or greater, or greater Or equal to 55lbs/in. In certain embodiments, the dry tensile strength of the open support layer is less than or equal to 60 lbs/in, less than or equal to 55 lbs/in, less than or equal to 50 lbs/in, less than or equal to 45 lbs/in, less than or equal to 40 lbs/in, 35 lbs/in or less, 30 lbs/in or less, 25 lbs/in or less, 20 lbs/in or less, 15 lbs/in or less, 10 lbs/in or less, 71 lbs/in or less, or Less than or equal to 51bs/in. Combinations of the above mentioned ranges are also possible (eg, dry tensile strength greater than or equal to 4 lbs/in and less than or equal to 60 lbs/in, greater than or equal to 10 lbs/in and less than or equal to 30 lbs/in). Other ranges are also possible. Dry tensile strength, as determined herein, is measured according to standard EN/ISO 1924-4, using a jaw separation speed of 10 mm/min and a sample size of 3 inches by 6 inches.

In some cases, the open support layer can have a specific thickness. For example, in some embodiments, the thickness is greater than or equal to 10 microns, greater than or equal to 15 microns, greater than or equal to 20 microns, greater than or equal to 50 microns, greater than or equal to 75 microns, greater than or equal to 100 microns, greater than or equal to 250 microns , greater than or equal to 500 microns, greater than or equal to 750 microns, greater than or equal to 1 mm, greater than or equal to 1.25 mm, greater than or equal to 1.5 mm, or greater than or equal to 1.75 mm. In some embodiments, the thickness of the open support layer can be less than or equal to 2mm, less than or equal to 1.75mm, less than or equal to 1.5mm, less than or equal to 1.25mm, less than or equal to 1mm, less than or equal to 750 microns, less than or equal to 500 microns, less than or equal to 250 microns, less than or equal to 100 microns, less than or equal to 75 microns, less than or equal to 50 microns, less than or equal to 20 microns, or less than or equal to 15 microns. Combinations of the above-mentioned ranges are also possible (eg, thickness greater than or equal to 10 microns and less than or equal to 2 mm, greater than or equal to 250 microns and less than or equal to 2 mm). Other ranges are also possible. As determined herein, thickness can be measured according to ASTM standard D-1777 at 0.3 psi.

In certain embodiments, the dry tensile elongation at break of the open support layer may be greater than or equal to 5%. For example, in some embodiments, the dry tensile elongation at break of the open support layer can be greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 20%, greater than or equal to 30%, greater than or equal to 40%, 50% or greater, 60% or greater, 70% or greater, 80% or greater, 90% or greater, 100% or greater, 110% or greater, 120% or greater, or Equal to 130%, or greater than or equal to 140%. In certain embodiments, the dry tensile elongation at break of the open support layer may be less than or equal to 150%, less than or equal to 140%, less than or equal to 130%, less than or equal to 120%, less than or equal to 110%, less than or equal to 100% or less, 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less %, or less than or equal to 10%. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 5% and less than or equal to 150%, greater than or equal to 10% and less than or equal to 60%). Other ranges are also possible. As determined herein, dry tensile elongation at break is measured according to standard EN/ISO 1924-4 using a jaw separation speed of 10 mm/min.

The first layer (e.g., an open support layer such as a mesh) and the second layer (e.g., a charged fiber layer) can be bonded to each other (e.g., by mechanically attaching, laminating, point bonding, thermal point bonding, ultrasonic bonding , calendering, use of adhesives (eg, glue webs) and/or co-pleating). In some embodiments, the first layer (eg, the open support layer) and the second layer can be mechanically attached. Non-limiting examples of suitable means for mechanical attachment include needling, suturing, and hydroentangling. In a specific set of embodiments, the first layer is needle punched to the second layer. In certain embodiments, the first layer and the second layer can be mechanically attached to each other such that the filter media including the first layer and the second layer are substantially free of adhesive. For example, in some embodiments, the open support layer is mechanically attached to the second layer (eg, charged fiber layer) and bonded to each other without an adhesive. In alternative embodiments, the open support layer and the second layer may be joined to each other by mechanical attachment and adhesives.

In embodiments where a first layer (eg, an open support layer, such as a mesh) is needled to a second layer (eg, a charged fiber layer), the needling may have a particular perforation density. In some embodiments, the needle punching has a perforation density greater than or equal to 1 perforation/cm2, greater than or equal to 2 perforations/cm2, greater than or equal to 3 perforations/cm2, and greater than or equal to 5 perforations/cm2 , greater than or equal to 7 perforations/cm², greater than or equal to 10 perforations/cm², greater than or equal to 15 perforations/cm², greater than or equal to 20 perforations/cm², greater than or equal to 25 perforations/cm² , greater than or equal to 30 perforations/cm², greater than or equal to 35 perforations/cm², greater than or equal to 40 perforations/cm², greater than or equal to 45 perforations/cm², greater than or equal to 50 perforations/cm² , or greater than or equal to 55 perforations/cm². In certain embodiments, the needle penetration density is less than or equal to 60 perforations/cm2, less than or equal to 55 perforations/cm2, less than or equal to 50 perforations/cm2, less than or equal to 45 perforations/cm2 , less than or equal to 40 perforations/cm2, less than or equal to 35 perforations/cm2, less than or equal to 30 perforations/cm2, less than or equal to 25 perforations/cm2, less than or equal to 20 perforations/cm2 , less than or equal to 15 perforations/cm2, less than or equal to 10 perforations/cm2, less than or equal to 7 perforations/cm2, less than or equal to 5 perforations/cm2, less than or equal to 3 perforations/cm2 , or less than or equal to 2 perforations/cm2. Combinations of the above-mentioned ranges are also possible (for example, greater than or equal to 1 perforation/cm2 and less than or equal to 60 perforations/cm2, greater than or equal to 1 perforation/cm2 and less than or equal to 10 perforations/cm2 square centimeter, greater than or equal to 15 perforations/square centimeter and less than or equal to 60 perforations/square centimeter, greater than or equal to 25 perforations/square centimeter and less than or equal to 45 perforations/square centimeter). Other ranges are also possible.

The open support layer can be needled to the charged fiber layer using a specific needle penetration depth spanning at least two layers. In certain embodiments, the needle penetration depth across two or more layers of the filter media (e.g., the open support layer and the charged fiber layer) is greater than or equal to 8 mm, greater than or equal to 10 mm, greater than or equal to 12 mm, Greater than or equal to 14mm, greater than or equal to 16mm, or greater than or equal to 18mm. In certain embodiments, the needle penetration depth across two or more layers of the filter media is less than or equal to 20 mm, less than or equal to 18 mm, less than or equal to 16 mm, less than or equal to 14 mm, less than or equal to 12 mm, or Less than or equal to 10mm. Combinations of the above mentioned ranges are also possible (eg needle penetration depth greater than or equal to 8 mm and less than or equal to 20 mm, greater than or equal to 12 mm and less than or equal to 16 mm). Other ranges are also possible.

As described above and herein, in some embodiments, the second layer is a charged fiber layer. In certain embodiments, the charged fibrous layer comprises a plurality of fibers. The fibers of the second layer may be discontinuous (eg, staple fibers).

As described herein, charged fiber layers may have certain structural characteristics, such as basis weight and/or fiber diameter. For example, in some embodiments, the charged fiber layer may have a basis weight greater than or equal to 12 g/m ² , greater than or equal to 15 g/m ² , greater than or equal to 20 g/m ² , greater than or equal to 25 g/m ² , greater than or equal to 30g/m ² , greater than or equal to 40g/m ² , greater than or equal to 50g/m ² , greater than or equal to 60g/m ² , greater than or equal to 70g/m ² , greater than or equal to 80g/m ² , greater than or equal to 100g/m 2 m ² , greater than or equal to 200g/m ² , greater than or equal to 300g/m ² , greater than or equal to 400g/m ² , greater than or equal to 500g/m ² , or greater than or equal to 600g/m ² . In some cases, the charged fiber layer may have a basis weight less than or equal to 700 g/m ² , less than or equal to 600 g/m ² , less than or equal to 500 g/m ² , less than or equal to 400 g/m ² , less than or equal to 300 g/m 2 ² , less than or equal to 200g/m ² , less than or equal to 100g/m ² , less than or equal to 90g/m ² , less than or equal to 80g/m ² , less than or equal to 70g/m ² , less than or equal to 60g/m ² , Less than or equal to 50g/m ² , less than or equal to 40g/m ² , less than or equal to 30g/m ² , less than or equal to 25g/m ² , less than or equal to 20g/m ² , or less than or equal to 15g/m ² . Combinations of the above-mentioned ranges are also possible (for example, the fixed weight is greater than or equal to 12g/m ² and less than or equal to 700g/m ² , the fixed weight is greater than or equal to 12g/m ² and less than or equal to 250g/ ^m greater than or equal to 15g/m ² and less than or equal to 100g/m ² ). Other values of fixed weight are also possible. The fixed weight can be determined as described above.

In some embodiments, a charged fibrous layer may comprise a plurality of fibers having a particular average fiber diameter. In some embodiments, the average fiber diameter of the plurality of fibers of the second layer is greater than or equal to 1 micron, greater than or equal to 2 microns, greater than or equal to 3 microns, greater than or equal to 5 microns, greater than or equal to 7 microns, greater than or equal to 9 microns, greater than or equal to 10 microns, greater than or equal to 12 microns, greater than or equal to 14 microns, greater than or equal to 15 microns, greater than or equal to 16 microns, greater than or equal to 18 microns, greater than or equal to 19 microns, greater than or equal to 20 microns , or greater than or equal to 21 microns. In certain embodiments, the average fiber diameter of the plurality of fibers of the second layer is less than or equal to 22 microns, less than or equal to 21 microns, less than or equal to 20 microns, less than or equal to 19 microns, less than or equal to 18 microns, less than or equal to 16 microns or less, 15 microns or less, 14 microns or less, 12 microns or less, 10 microns or less, 9 microns or less, 7 microns or less, 5 microns or less, 4 or less microns, less than or equal to 3 microns, or less than or equal to 2 microns. Combinations of the above-mentioned ranges are also possible (e.g., average fiber diameter greater than or equal to 1 micron and less than or equal to 22 microns, greater than or equal to 1 micron and less than or equal to 15 microns, greater than or equal to 15 microns and less than or equal to 22 microns). Other ranges are also possible.

In some embodiments, the charged fibrous layer may comprise a plurality of fibers that are relatively thin (eg, having an average fiber diameter of less than 15 microns). For example, in certain embodiments, the second layer comprises an average fiber diameter of less than 15 microns, less than or equal to 14 microns, less than or equal to 12 microns, less than or equal to 10 microns, less than or equal to 9 microns, less than or equal to 7 microns, Multiple fibers less than or equal to 5 microns, less than or equal to 4 microns, less than or equal to 3 microns, or less than or equal to 2 microns. In some embodiments, the second layer comprises an average fiber diameter greater than or equal to 1 micron, greater than or equal to 2 microns, greater than or equal to 3 microns, greater than or equal to 5 microns, greater than or equal to 7 microns, greater than or equal to 9 microns, greater than Or a plurality of fibers equal to 10 microns, greater than or equal to 12 microns, or greater than or equal to 14 microns. Combinations of the above-mentioned ranges are also possible (eg, less than 15 microns and greater than or equal to 1 micron, less than 15 microns and greater than or equal to 3 microns, less than or equal to 12 microns and greater than or equal to 3 microns). Other ranges are also possible. In an exemplary embodiment, a filter media includes an open support layer (i.e., a first layer) and a charged fiber layer (i.e., a second layer) adjacent to the open support layer, the charged fiber layer comprising polycarbonate fibers having an average fiber diameter of less than 15 microns. root fiber.

As described herein, in some embodiments, a charged fibrous layer may comprise one or more plurality of fibers. For example, in certain embodiments, a charged fibrous layer comprises a first plurality of fibers (eg, comprising a first polymer) and a second plurality of fibers (eg, comprising a second polymer different from the first polymer). In some such embodiments, each of the plurality of fibers (eg, first plurality of fibers, second plurality of fibers) can have an average fiber diameter as described above. For example, in an exemplary embodiment, the charged fibrous layer comprises a first plurality of fibers and a second plurality of fibers, the average fiber diameter of the first plurality of fibers and/or the second plurality of fibers being less than 15 microns and greater than or equal to 1 micron. In another exemplary embodiment, the charged fibrous layer comprises a first plurality of fibers and a second plurality of fibers, the average fiber diameter of the first plurality of fibers and/or the second plurality of fibers being greater than or equal to 1 micron and less than or equal to Equal to 22 microns.

In certain embodiments, the plurality of fibers of the charged fibrous layer comprises synthetic fibers (synthetic polymer fibers). The synthetic fibers of the second layer may be staple fibers. Non-limiting examples of suitable synthetic fibers include polypropylene, dry spun acrylic (e.g., produced by a dry spinning process), polyvinyl chloride, modified acrylic, wet spun acrylic, polytetrafluoroethylene, polypropylene, polypropylene Styrene, polysulfone, polyethersulfone, polycarbonate, nylon (for example, nylon 6/6), polyurethane, phenolic resin, polyvinylidene fluoride, polyester, polyaramid, polyimide, polyolefin ( e.g. polyethylene), Kevlar, Nomex, halogenated polymers (e.g. polyethylene terephthalate), polyacrylics, polyphenylene ether, polyphenylene sulfide , polymethylpentene, and combinations thereof. In some embodiments, the synthetic fibers are halogen-free such that no significant amounts of dioxins can be detected upon incineration. For example, the fibers may be halogen-free acrylic fibers formed by dry spinning. In some embodiments, the second layer and/or the entire filter media are halogen-free such that no significant amounts of dioxins can be detected upon incineration.

In some embodiments, the charged fibrous layer comprises a mixture of two or more polymer fibers. For example, a charged fibrous layer may comprise at least a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer. For example, in an exemplary embodiment, the charged fibrous layer comprises a first plurality of fibers comprising a first polymer, wherein the first polymer is acrylic (eg, dry spun acrylic). In certain embodiments, the charged fibrous layer comprises a second plurality of fibers comprising a second type of polymeric fiber different from the first type of polymeric fiber. In certain embodiments, the second type of polymer fiber is polypropylene.

In certain embodiments, the first polymer and the second polymer are selected such that the first polymer and the second polymer have different dielectric constants. Two polymers with different dielectric constants can contribute to charging (eg, tribocharging) the layer. Without wishing to be bound by theory, two polymers in a layer with different dielectric constants may come into frictional contact during fabrication of the layer such that one polymer will lose electrons and give them to the other polymer, thus losing The polymer that receives the electron is net positive, and the other polymer that receives the electron is net negative. In embodiments where the second layer of the filter media is a charged fibrous layer, the charged layer may have a patent document entitled "Filter materials and methods for the production therefore of One or more features described in commonly-owned U.S. Patent No. 6,623,548. For example, in some embodiments, the second layer is an electrostatically charged layer formed by combining polypropylene fibers with halogen-free acrylic fibers, polypropylene with polyvinyl chloride (PVC) fibers, or halogen-free A mixture of acrylic fibers and PVC fibers is mixed together, and the mixed fibers are optionally carded to form a nonwoven fabric.

In some embodiments, the difference in dielectric constant between the first polymer and the second polymer can be selected to be greater than or equal to 0.8, greater than or equal to 1, greater than or equal to 1.2, greater than or equal to 1.5, greater than or equal to 2, 3 or greater, 5 or greater, or 7 or greater. In certain embodiments, the difference in dielectric constant between the first polymer and the second polymer can be selected to be 8 or less, 7 or less, 5 or less, 3 or less, 2 or less , less than or equal to 1.5, less than or equal to 1.2, or less than or equal to 1. Combinations of the above-mentioned ranges are also possible (eg, the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 0.8 and less than or equal to 8, greater than or equal to 1.5 and less than or equal to 5). Other ranges are also possible.

Table 1 shows representative dielectric constants for several exemplary polymers.

Table 1

The first polymer and the second polymer can be present in the second layer in any suitable amount. For example, in some embodiments, the first polymer is present in an amount of greater than or equal to 10 wt%, greater than or equal to 15 wt%, greater than or equal to 20 wt%, relative to the total amount of fibers in the layer and/or the total weight of the layer, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 65% by weight or more, Or equal to 70 wt%, greater than or equal to 75 wt%, greater than or equal to 80 wt%, or greater than or equal to 85 wt% is present in the second layer. In certain embodiments, the first polymer is present in an amount of less than or equal to 90 wt%, less than or equal to 85 wt%, less than or equal to 80 wt%, less than or equal to the total weight of the layer relative to the total amount of fibers in the layer and/or the total weight of the layer or equal to 75% by weight, less than or equal to 70% by weight, less than or equal to 65% by weight, less than or equal to 60% by weight, less than or equal to 50% by weight, less than or equal to 40% by weight, less than or equal to 35% by weight, less than or equal to An amount equal to 30 weight percent, less than or equal to 25 weight percent, less than or equal to 20 weight percent, or less than or equal to 15 weight percent is present in the second layer. Combinations of the above-mentioned ranges are also possible (for example, greater than or equal to 10 wt. % and less than or equal to 90 wt. %, greater than or equal to 25 wt. % and less than or equal to 75 wt. %, greater than or equal to 35 wt. equal to 65% by weight). Other ranges are also possible.

In some embodiments, the second polymer is present in an amount of less than or equal to 90% by weight, less than or equal to 85% by weight, less than or equal to 80% by weight, less than or equal to 80% by weight, relative to the total amount of fibers in the layer and/or the total weight of the layer 75% by weight, 70% by weight or less, 65% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 35% by weight or less, 35% by weight or less 30 wt%, less than or equal to 25 wt%, less than or equal to 20 wt%, or less than or equal to 15 wt% is present in the second layer. In certain embodiments, the second polymer is present in an amount of greater than or equal to 10 wt%, greater than or equal to 15 wt%, greater than or equal to 20 wt%, greater than or equal to the total weight of the layer relative to the total amount of fibers in the layer and/or the total weight of the layer or equal to 25% by weight, greater than or equal to 30% by weight, greater than or equal to 35% by weight, greater than or equal to 40% by weight, greater than or equal to 50% by weight, greater than or equal to 60% by weight, greater than or equal to 65% by weight, greater than or equal to An amount equal to 70 weight percent, greater than or equal to 75 weight percent, greater than or equal to 80 weight percent, or greater than or equal to 85 weight percent is present in the second layer. Combinations of the above-mentioned ranges are also possible (for example, greater than or equal to 10 wt. % and less than or equal to 90 wt. %, greater than or equal to 25 wt. % and less than or equal to 75 wt. %, greater than or equal to 35 wt. equal to 65% by weight). Other ranges are also possible.

In some embodiments, the second layer comprises the first polymer in an amount of greater than or equal to 10% by weight and less than or equal to 90% by weight and an amount of less than or equal to 90% by weight and greater than or equal to 10% by weight of the second polymer. For example, in some embodiments, the second layer comprises, relative to the total amount of fibers in the layer, the first polymer in an amount greater than or equal to 25% by weight and less than or equal to 75% by weight and the amount of or equal to 25% by weight of the second polymer. In certain embodiments, the second layer may comprise the first polymer in an amount greater than or equal to 35% by weight and less than or equal to 65% by weight and an amount of less than or equal to 65% by weight and greater than or equal to 35% by weight of the second polymer. In certain embodiments, the second layer comprises each of the first polymer and the second polymer in an amount of about 50% by weight relative to the total amount of fibers in the layer.

In some embodiments, the charged fibrous layer comprises a plurality of fibers (eg, synthetic fibers, staple fibers) having an average length of less than 5 inches (127 mm). For example, the average length of the plurality of fibers in the charged fiber layer may be, for example, less than or equal to 100mm, less than or equal to 80mm, less than or equal to 60mm, less than or equal to 40mm, less than or equal to 20mm, less than or equal to 10mm, less than or equal to 5mm, Less than or equal to 1mm, less than or equal to 0.5mm, or less than or equal to 0.1mm. In some cases, the plurality of fibers in the charged fiber layer may have an average length greater than or equal to 0.02 mm, greater than or equal to 0.1 mm, greater than or equal to 0.5 mm, greater than or equal to 1 mm, greater than or equal to 5 mm, greater than or equal to 10 mm, Greater than or equal to 20mm, greater than or equal to 40mm, greater than or equal to 60mm. Combinations of the ranges mentioned above are possible (eg, greater than or equal to 1 mm and less than or equal to 80 mm, greater than or equal to 1 mm and less than or equal to 60 mm). Other ranges are also possible.

In some cases, charged fiber layers can be designed to have a relatively high surface area and/or a relatively low number of fibers per gram (layer). Advantageously and without wishing to be bound by theory, having a relatively high surface area per gram (layer) and a relatively high number of fibers per gram (layer) compared to a layer having a relatively low surface area per unit mass and/or a relatively high number of fibers per gram (layer) Charged fiber layers with a relatively low number of fibers (layers) may exhibit increased initial efficiency, increased charge generation (e.g., triboelectric charges), and/or reduced charge dissipation (e.g., in layers and/or filter during the use of the media).

In certain embodiments, the BET surface area of the charged fibrous layer is greater than or equal to 0.33 m ² /g, greater than or equal to 0.35 m ² /g, greater than or equal to 0.37 m ² /g, greater than or equal to 0.4 m ² /g, greater than or equal to 0.5m ² /g, greater than or equal to 0.6m ² /g, greater than or equal to 0.7m 2 /g, greater than or equal to 0.8m ^{2 /} g, greater than or equal to 0.9m ² /g, greater than or equal to 1m ² / g, or greater than or equal to 1.2m ² /g. In some embodiments, the BET surface area of the charged fibrous layer is less than or equal to 1.5 m ² /g, less than or equal to 1.2 m ² /g, less than or equal to 1 m ² /g, less than or equal to 0.9 m ² /g, less than or equal to 0.8m ² /g, less than or equal to 0.75m ² /g, less than or equal to 0.7m ² /g, less than or equal to 0.6m ² /g, less than or equal to 0.5m ² /g, less than or equal to 0.4m ² /g , less than or equal to 0.37m ² /g, or less than or equal to 0.35m ² /g. Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 0.33 m ² /g and less than or equal to 1.5 m ² /g, greater than or equal to 0.35 m ² /g and less than or equal to 1 m ² /g). Other ranges are also possible.

As determined herein, BET surface area is measured using standard BET surface area measurement techniques. The BET surface area is measured according to Section 10 of the Battery Council International Standard (Battery Council International Standard) BCIS-03A "Recommended Battery Materials Specifications Valve Regulated Recombinant Batteries", which is "Recombinant Batteries Standard Test Method for Surface Area of Recombinant BatterySeparator Mat". According to this technique, the BET surface area is measured by adsorption analysis using a BET surface analyzer (e.g., Micromeritics Gemini III 2375 surface area analyzer) with nitrogen; the sample size is 0.5 g to 0.6 g in a 3/4" tube; Degas for a minimum of 3 hours at °C.

In certain embodiments, the charged fibrous layer has a specific number of fibers per gram (fibrous layer). In some embodiments, the charged fibrous layer has less than or equal to 125,000 fibers, less than or equal to 120,000 fibers, less than or equal to 110,000 fibers, less than or equal to 105,000 fibers, less than or equal to 103,000 fibers per gram (fibrous layer) , 100,000 fibers or less, 95,000 fibers or less, 90,000 fibers or less, 80,000 fibers or less, 75,000 fibers or less, 70,000 fibers or less, or 60,000 fibers or less . In certain embodiments, the charged fibrous layer has greater than or equal to 50,000 fibers, greater than or equal to 60,000 fibers, greater than or equal to 70,000 fibers, greater than or equal to 75,000 fibers, greater than or equal to 80,000 fibers per gram (fibrous layer) Fibers, 90,000 fibers or more, 95,000 fibers or more, 100,000 fibers or more, 103,000 fibers or more, 105,000 fibers or more, 110,000 fibers or more, or 120,000 fibers or more fiber. Combinations of the above-mentioned ranges are also possible (eg, less than or equal to 125,000 fibers per gram and greater than or equal to 50,000 fibers, less than or equal to 105,000 fibers per gram and greater than or equal to 75,000 fibers). Other ranges are also possible. Based on the teaching of this specification, those skilled in the art can choose a suitable method to determine the number of fibers per gram of fiber layer. For example, the number of fibers per gram (fibrous layer) can be determined by dividing the average BET surface area of the fibrous layer (eg, charged fiber layer) by the average geometric surface area of the fibers in the (charged) fibrous layer. In some cases, the average geometric surface area of the fibers in the (charged) fiber layer can be determined by measuring the average cross-sectional perimeter of the fibers (eg, by scanning electron microscopy) and multiplying by the average fiber length.

In an exemplary embodiment, the charged fiber layer has a BET surface area greater than or equal to 0.33 m ² /g (eg, greater than or equal to 0.33 m ² /g and less than or equal to 1.5 m ² /g) and less than or equal to 125,000 fibers /g (charged fiber layer) (for example, less than or equal to 125,000 fibers/g and greater than or equal to 50,000 fibers/g).

In some embodiments, the first plurality of fibers and/or the second plurality of fibers of the charged fibrous layer have a particular average largest cross-sectional dimension, for example greater than or equal to 2 microns, greater than or equal to 2.5 microns, greater than or equal to 3 microns, 5 microns or greater, 7 microns or greater, 9 microns or greater, 10 microns or greater, 12 microns or greater, or 14 microns or greater. In some embodiments, the average largest cross-sectional dimension of the first plurality of fibers and/or the second plurality of fibers of charged fibers is less than or equal to 15 microns, less than or equal to 14 microns, less than or equal to 12 microns, less than or equal to 10 microns , less than or equal to 9 microns, less than or equal to 7 microns, less than or equal to 5 microns, or less than or equal to 3 microns. Combinations of the above mentioned ranges are also possible (eg, greater than or equal to 2 microns and less than or equal to 15 microns). Other ranges are also possible. The average maximum cross-sectional dimension of the fibers (eg, first plurality of fibers, second plurality of fibers) can be determined according to testing standard ASTM D-2130.

In certain embodiments, the first plurality of fibers and/or the second plurality of fibers of the charged fibrous layer can be designed to have a specific cross-sectional shape. In some embodiments, the cross-sectional shape of the first plurality of fibers and/or the second plurality of fibers is selected from the group consisting of circular, oval, dog-bone, kidney bean, ribbon, irregular, and multilobal. In a specific set of embodiments, the first plurality of fibers and/or the second plurality of fibers have a multilobal shape (eg, bilobal, trilobal, quadrilobal, pentalobal, multilobal). As used herein, a multilobal fiber generally refers to a fiber having two or more (e.g., three or more, four or more, five or more) leaflets at the cross-section of the fiber. The core extends the fibers of the blade. In some cases, the vanes can be the same or a different material than the core. In some embodiments, the lobes and core of the fiber are the same material. In certain embodiments, the fibers are bicomponent or multicomponent fibers (eg, the blade and core comprise different materials).

In some embodiments, the charged fiber layer can be engineered to have a specific uncompressed thickness. In some embodiments, the uncompressed thickness of the charged fiber layer can be greater than or equal to 5 mils, greater than or equal to 10 mils, greater than or equal to 25 mils, greater than or equal to 30 mils, greater than or equal to 50 mils Lug, 100 mil or greater, 200 mil or greater, 250 mil or greater, 300 mil or greater, 350 mil or greater, 400 mil or greater, 450 mil or greater , or greater than or equal to 500 mils. In certain embodiments, the uncompressed thickness of the charged fiber layer can be less than or equal to 600 mils, less than or equal to 500 mils, less than or equal to 450 mils, less than or equal to 400 mils, less than or equal to 350 mils, 300 mils or less, 250 mils or less, 200 mils or less, 100 mils or less, 50 mils or less, 25 mils or less, or 10 mils or less. Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 5 mils and less than or equal to 600 mils, greater than or equal to 30 mils and less than or equal to 350 mils). Other ranges are also possible. As used herein, uncompressed thickness is determined using a Mitutoyo thickness gauge. Briefly, the fiber layer was compressed using a circular probe with a diameter of 1 mm under at least three different weights (eg, 10 grams, 5 grams, 2 grams). An ordinary least squares linear regression was determined for each weight and corresponding thickness and used to calculate the thickness of the fibrous layer corresponding to an applied weight of 0 grams (ie, the uncompressed thickness of the layer).

In certain embodiments, the charged fibrous layer may have a specific air permeability. In some embodiments, the charged fiber layer has an air permeability greater than or equal to 10 CFM, greater than or equal to 25 CFM, greater than or equal to 50 CFM, greater than or equal to 80 CFM, greater than or equal to 100 CFM, greater than or equal to 200 CFM, greater than or equal to 250 CFM, greater than or equal to 300CFM, greater than or equal to 350CFM, greater than or equal to 400CFM, greater than or equal to 450CFM, greater than or equal to 500CFM, greater than or equal to 550CFM, greater than or equal to 600CFM, greater than or equal to 650CFM, greater than or equal to 700CFM, greater than or equal to 750CFM, greater than or equal to 800CFM, greater than or equal to 850CFM, greater than or equal to 900CFM, greater than or equal to 950CFM, greater than or equal to 1000CFM, greater than or equal to 1050CFM, greater than or equal to 1100CFM, or greater than or equal to 1150CFM. In certain embodiments, the air permeability of the charged fiber layer is less than or equal to 1200 CFM, less than or equal to 1150 CFM, less than or equal to 1100 CFM, less than or equal to 1050 CFM, less than or equal to 1000 CFM, less than or equal to 950 CFM, less than or equal to 900 CFM, less than or equal to Equal to 850CFM, less than or equal to 800CFM, less than or equal to 750CFM, less than or equal to 700CFM, less than or equal to 650CFM, less than or equal to 600CFM, less than or equal to 550CFM, less than or equal to 500CFM, less than or equal to 450CFM, less than or equal to 400CFM, less than or equal to Equal to 350CFM, less than or equal to 300CFM, less than or equal to 250CFM, less than or equal to 200CFM, less than or equal to 150CFM, less than or equal to 100CFM, less than or equal to 80CFM, less than or equal to 50CFM, or less than or equal to 25CFM. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 10 CFM and less than or equal to 1200 CFM, greater than or equal to 80 CFM and less than or equal to 1200 CFM, greater than or equal to 50 CFM and less than or equal to 650 CFM). Other ranges are also possible. As used herein, the air permeability of the second layer is measured according to test standard ASTM D737 over a media surface area of 38 cm ² and using a pressure of 125 Pa.

In some embodiments, a filter media includes a first layer and a second layer as described above and herein. For example, in one set of embodiments, a filter media includes an open support layer (ie, a first layer) and a layer of charged fibers mechanically attached to the open support layer (ie, a second layer). Referring again to FIG. 1A , in some embodiments, filter media 100 includes an open support layer (ie, first layer 110 ) mechanically attached to a charged fibrous layer (ie, second layer 120 ). In some such embodiments, the open support layer has an air permeability of greater than 1100 CFM and less than or equal to 20,000 CFM and/or a solidity of less than or equal to 10%. In some cases, the open support layer can be a mesh. In some embodiments, the filter media includes an open support layer (eg, a mesh) mechanically attached (eg, needle punched) to a charged fiber layer comprising a plurality of fibers having relatively low fiber diameters. Without wishing to be bound by theory, incorporation of fibers having relatively low fiber diameters (eg, less than 15 microns) increases the surface area of the fiber layer and generally increases filtration performance and/or provides relatively low pressure drop across the fiber layer.

As noted above, in some embodiments, the filter media can include one or more additional layers associated with the first layer (eg, the open support layer). In some cases, the one or more additional layers may be selected from meltblown layers, spunbond layers, or carded layers.

For example, in some embodiments at least one of the one or more additional layers is a meltblown layer. In some such embodiments, the additional layer can be formed by a meltblowing process and/or comprise fibers formed by a meltblowing process. The meltblowing process is described in more detail below. In certain embodiments, at least one of the one or more additional layers is a spunbond layer. For example, a spunbond layer may be formed by a spunbond process and/or contain fibers formed by a spunbond process.

In some cases, at least one of the one or more additional layers may be a carded fiber layer.

A first layer (e.g., an open support layer, such as a mesh) and/or one or more additional layers (e.g., a meltblown layer) may be bonded to another layer, such as a layer of charged fibers (e.g., by mechanical attachment, layer bonding, point bonding, thermal point bonding, ultrasonic bonding, calendering, use of adhesives (e.g. glue webs) and/or co-pleating). In some embodiments, the open support layer and additional layers may be mechanically attached to, for example, charged fiber layers. In a specific set of embodiments, the open support layer and/or the additional layer are laminated to the charged support layer. In another set of embodiments, the open support layer and/or the additional layer is needle punched to the charged support layer. In certain embodiments, the open support layer, additional layers, and/or charged fiber layers can be mechanically attached to each other such that the filter media including the open support layer, additional layers, and charged fiber layers are substantially free of binders. For example, in some embodiments, the open support layer is mechanically attached to the additional layer and/or the charged fiber layer and joined to each other without an adhesive. In alternative embodiments, the open support layer, additional layers and/or charged fiber layers may be joined to each other by mechanical attachment and adhesives. In one set of embodiments, the open support layer, additional layers, and/or charged fiber layers may be maintained in a corrugated configuration. For example, in certain embodiments, the filter media includes a coarse support layer that maintains the open support layer, additional layers, and/or charged fiber layers in a corrugated configuration to maintain the alignment of the peaks and troughs of adjacent waves of the layers. separate. In another set of embodiments, the open support layer, additional layer, and/or charged fiber layer can be non-corrugated (eg, substantially planar).

In some embodiments, (each of) the additional layers may have greater than or equal to 2 g/m ² , greater than or equal to 3 g/m ² , greater than or equal to 5 g/m ² , greater than or equal to 7 g/m ² , greater than or equal to 10g/m ² , greater than or equal to 12g/m ² , greater than or equal to 15g/m ² , greater than or equal to 20g/m 2 , greater than or equal to 25g/ ^{m 2 ,} greater than or equal to 30g/m ² , greater than or equal to 35g/m ² , greater than or equal to 40g/m ² , greater than or equal to 45g/m ² , greater than or equal to 50g/m ² , greater than or equal to 55g/m ² , greater than or equal to 60g/m ² , greater than or equal to 65g/m 2 m ² , greater than or equal to 70g/m ² , greater than or equal to 75g/m ² , greater than or equal to 80g/m ² , greater than or equal to 85g/m ² , greater than or equal to 90g/m ² , or greater than or equal to 95g/m ² specific fixed weight. In some embodiments, the (each of) additional layers have a basis weight less than or equal to 100 g/m ² , less than or equal to 95 g/m ² , less than or equal to 90 g/m ² , less than or equal to 85 g/m ² , Less than or equal to 80g/m ² , less than or equal to 75g/m ² , less than or equal to 70g/m 2 , less than or equal to 65g/m ² , less than or equal to 60g/ ^{m 2 ,} less than or equal to 55g/m ² , less than or equal to Equal to 50g/m ² , less than or equal to 45g/m ² , less than or equal to 40g/m ² , less than or equal to 35g/m ² , less than or equal to 30g/m ² , less than or equal to 25g/m ² , less than or equal to 20g /m ² , less than or equal to 15 g/m ² , less than or equal to 12 g/m ² , less than or equal to 10 g/m ² , less than or equal to 7 g/m ² , or less than or equal to 5 g/m ² . Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 2 g/m ^{2 and less than or equal to 100 g/m 2 , greater than or equal to 2 g/m 2 and} less than 5 g/m ² ). Other ranges are also possible. In an exemplary embodiment, at least one of the one or more additional layers is a meltblown layer having a basis weight greater than or equal to 2 g/m ² and less than or equal to 100 g/m ² .

In certain embodiments, the additional layer may have a thickness of 4 mils or greater, 5 mils or greater, 6 mils or greater, 8 mils or greater, 10 mils or greater, 12 mils or greater mil, greater than or equal to 15 mil, greater than or equal to 18 mil, greater than or equal to 20 mil, or greater than or equal to 22 mil of the specified thickness. In certain embodiments, each additional layer has a thickness of 25 mils or less, 22 mils or less, 20 mils or less, 18 mils or less, 15 mils or less, 15 mils or less, 12 mils, 10 mils or less, 8 mils or less, 6 mils or less, or 5 mils or less. Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 4 mils and less than or equal to 25 mils). Other ranges are also possible.

In some embodiments, the combined basis weight of the additional layer and the open support layer may be greater than or equal to 10 g/m ² , greater than or equal to 15 g/m ² , greater than or equal to 20 g/m ² , greater than or equal to 25 g/m ² , greater than or equal to or equal to 30g/m ² , greater than or equal to 35g/m ² , greater than or equal to 40g/m ² , greater than or equal to 45g/m ² , greater than or equal to 50g/m ² , greater than or equal to 55g/m ² , greater than or equal to 60g/m ² , greater than or equal to 65g/m ² , greater than or equal to 70g/m ² , greater than or equal to 75g/m ² , greater than or equal to 80g/m ² , greater than or equal to 85g/m ² , greater than or equal to 90g/m 2 m ² , greater than or equal to 95g/m ² , greater than or equal to 100g/m ² , greater than or equal to 110g/m ² , greater than or equal to 120g/m ² , or greater than or equal to 130g/m ² . In some embodiments, the combined basis weight of the additional layer and the open support layer is less than or equal to 140 g/m ² , less than or equal to 130 g/m ² , less than or equal to 120 g/m ² , less than or equal to 110 g/m ² , less than or equal to Equal to 100g/m ² , less than or equal to 95g/m ² , less than or equal to 90g/m ² , less than or equal to 85g/m ² , less than or equal to 80g/m ² , less than or equal to 75g/m ² , less than or equal to 70g /m ² , less than or equal to 65g/m ² , less than or equal to 60g/m ² , less than or equal to 55g/m ² , less than or equal to 50g/m ² , less than or equal to 45g/m ² , less than or equal to 40g/m ² , less than or equal to 35g/m ² , less than or equal to 30g/m ² , less than or equal to 25g/m ² , or less than or equal to 20g/m ² . Combinations of the above mentioned ranges are also possible (eg greater than or equal to 10 g/m ² and less than or equal to 140 g/m ² ).

In some embodiments, each additional layer can have a particular average fiber diameter. In certain embodiments, the average fiber diameter of the additional layer may be greater than or equal to 0.5 microns, greater than or equal to 1 micron, greater than or equal to 2 microns, greater than or equal to 3 microns, greater than or equal to 5 microns, greater than or equal to 8 microns, Greater than or equal to 10 microns, greater than or equal to 12 microns, greater than or equal to 15 microns, or greater than or equal to 17 microns. In some embodiments, the average fiber diameter of the additional layer can be less than or equal to 20 microns, less than or equal to 17 microns, less than or equal to 15 microns, less than or equal to 12 microns, less than or equal to 10 microns, less than or equal to 8 microns, less than or equal to or equal to 5 microns, less than or equal to 3 microns, less than or equal to 2 microns, or less than or equal to 1 micron. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 1 micron and less than or equal to 20 microns).

Each additional layer can be selected to have a specific air permeability. In some embodiments, the additional layer has an air permeability greater than or equal to 45 CFM, greater than or equal to 50 CFM, greater than or equal to 75 CFM, greater than or equal to 100 CFM, greater than or equal to 200 CFM, greater than or equal to 300 CFM, greater than or equal to 400 CFM, greater than or equal to 500 CFM , greater than or equal to 600CFM, greater than or equal to 700CFM, greater than or equal to 800CFM, greater than or equal to 900CFM, or greater than or equal to 1000CFM. In some embodiments, the additional layer has an air permeability of less than 1100 CFM, less than or equal to 1000 CFM, less than or equal to 900 CFM, less than or equal to 800 CFM, less than or equal to 700 CFM, less than or equal to 600 CFM, less than or equal to 500 CFM, less than or equal to 400 CFM, less than or equal to Or equal to 300CFM, less than or equal to 200CFM, less than or equal to 100CFM, less than or equal to 75CFM, or less than or equal to 50CFM. Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 45 CFM and less than 1100 CFM). Other ranges are also possible.

In some cases, the open support layer and the additional layer may have a specific combined air permeability. In some embodiments, the combined air permeability of the open support layer and the additional layer is greater than or equal to 45 CFM, greater than or equal to 50 CFM, greater than or equal to 75 CFM, greater than or equal to 100 CFM, greater than or equal to 200 CFM, greater than or equal to 300 CFM, greater than or equal to 400 CFM , greater than or equal to 500CFM, greater than or equal to 600CFM, greater than or equal to 700CFM, greater than or equal to 800CFM, greater than or equal to 900CFM, or greater than or equal to 1000CFM. In some embodiments, the combined air permeability of the open support layer and the additional layer is less than 1100 CFM, less than or equal to 1000 CFM, less than or equal to 900 CFM, less than or equal to 800 CFM, less than or equal to 700 CFM, less than or equal to 600 CFM, less than or equal to 500 CFM, less than or equal to Or equal to 400CFM, less than or equal to 300CFM, less than or equal to 200CFM, less than or equal to 100CFM, less than or equal to 75CFM, or less than or equal to 50CFM. Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 45 CFM and less than 1100 CFM, greater than or equal to 45 CFM and less than or equal to 700 CFM). Other ranges are also possible.

In some embodiments, one or more additional layers are charged. In general, the one or more additional layers can be charged using any of a variety of techniques. Examples include AC and/or DC corona discharge, charging rods, tribo-charging, hydrocharging or use of additives. For example, a layer of filter media (e.g., one or more additional layers of filter media) can be charged by a hydrodynamic charging process by causing a polar fluid to This is done by impinging a jet and/or stream of (eg water) droplets onto the layer. The jet or stream of polar fluid may be provided by any suitable spraying method. During the hydrocharging process, the layer can be transported, for example, on a porous support such as a belt, mesh or fabric. During hydrocharging, in some cases a vacuum may be placed near the porous support, for example to help polar fluids pass through the layers. After hydrocharging, the layer can be dried (eg, by an air drying process). In other embodiments, one or more additional layers may be uncharged.

Advantageously, a meltblown layer charged by hydrodynamic charging as described herein (e.g., by a jet of polar fluid such as water) can be associated with an open support layer and laminated to a charged fiber layer, and with an uncharged meltblown layer has a relatively high combined gamma value compared to Combining gamma values is described in more detail below.

In some cases, one or more additional layers are fine fiber layers. In some embodiments, the fine fiber layer is formed by a solvent-based spinning process (eg, an electrospinning process). In some embodiments of filter media that include at least one fine fiber layer, the one or more fine fiber layers may comprise synthetic fibers, glass fibers, and/or cellulose fibers, among other fiber types. In some cases, the fine fiber layer may contain a relatively high weight percent of synthetic fibers (eg, 100% by weight). For example, one or more fine fiber layers may comprise synthetic fibers formed by a meltblowing process, a melt spinning process, a centrifugal spinning process, electrospinning, wet-laying, dry-laying or air-laying processes . In some cases, the synthetic fibers can be continuous, as described further below. In an exemplary embodiment, the fine fiber layer is formed (eg, comprises electrospun fibers) by an electrospinning process.

In a specific set of embodiments, the filter media includes an open support layer, a meltblown layer associated with (eg, directly adjacent to) the open support layer, and a layer of fine fibers associated with (eg, directly adjacent to) the meltblown layer.

In some embodiments, the filter media can include a fine fiber layer comprising synthetic fibers. Synthetic fibers can have a relatively small average fiber diameter (eg, less than or equal to about 2 microns). For example, the average cross-sectional dimension (eg, diameter) of the synthetic fibers in the fine fiber layer can be less than or equal to about 2 microns (eg, from about 0.08 microns to about 2.0 microns). In some embodiments, the synthetic fibers in the one or more fine fiber layers may be produced by any suitable process (e.g., melt blowing, melt spinning, electrospinning (e.g., melt electrospinning, solvent electrospinning) spinning), centrifugal spinning) formed continuous fibers. In certain embodiments, synthetic fibers can be formed by an electrospinning process. In other embodiments, the synthetic fibers may be discontinuous. In some embodiments, all fibers in the one or more fine fiber layers are synthetic fibers.

The synthetic fibers in the fine fiber layer may comprise any suitable type of synthetic polymer. Examples of suitable synthetic fibers include polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate), polycarbonates, polyamides (e.g., various nylon polymers), poly Aramid, polyimide, polyethylene, polypropylene, polyether ether ketone, polyolefin, acrylic (e.g., polyacrylic acid), polylactic acid, polyvinyl alcohol, polyvinyl chloride, regenerated cellulose (e.g., synthetic such as lyocell, rayon), polyacrylonitrile, polyvinylidene fluoride (PVDF), copolymers of polyethylene and PVDF, polyethersulfone, polycarbonate, and combinations thereof.

In some embodiments, the average diameter of the synthetic fibers of the one or more fine fiber layers (if present) can be, for example, greater than or equal to about 0.08 microns, greater than or equal to about 0.1 microns, greater than or equal to about 0.2 microns, greater than or equal to Equal to about 0.3 micron, greater than or equal to about 0.4 micron, greater than or equal to about 0.5 micron, greater than or equal to about 0.6 micron, greater than or equal to about 0.8 micron, greater than or equal to about 1 micron, greater than or equal to about 1.2 micron, greater than or equal to About 1.4 microns, greater than or equal to about 1.6 microns, or greater than or equal to about 1.8 microns. In some cases, the average diameter of the synthetic fibers of the one or more fine fiber layers (if present) can be less than or equal to about 2 microns, less than or equal to about 1.8 microns, less than or equal to about 1.6 microns, less than or equal to about 1.4 microns or less, about 1.2 microns or less, about 1 micron or less, about 0.8 microns or less, about 0.6 microns or less, about 0.5 microns or less, about 0.4 microns or less, about 0.3 microns or less microns, less than or equal to about 0.2 microns, or less than or equal to about 0.1 microns. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to about 0.08 microns and less than or equal to about 2 microns, greater than or equal to about 0.1 microns and less than or equal to about 1 micron). Other values for the average fiber diameter are also possible. The average diameter of the fibers can be determined, for example, by scanning electron microscopy.

In some cases, the synthetic fibers, if present, can be continuous (eg, meltblown fibers, spunbond fibers, electrospun fibers, centrifugal spun fibers, etc.). The lengths of the continuous fibers are provided above. In other embodiments, the synthetic fibers, if present, are not continuous (eg, staple fibers). The staple fiber lengths are provided above. Continuous fibers are made by a "continuous" fiber forming process, such as a meltblown process, a spunbond process, an electrospinning process, or a centrifugal spinning process, and typically have a longer length than discontinuous fibers. Discontinuous fibers are staple fibers that are typically cut (eg, from filaments) or formed into discontinuous discrete fibers to have a particular length or range of lengths.

In embodiments where the filter media includes a layer of fine fibers, the layer of fine fibers can have any suitable basis weight. In some embodiments, the basis weight of the fine fiber layer may be greater than or equal to 0.01 g/m ² , greater than or equal to 0.03 g/m ² , greater than or equal to 0.05 g/m ² , greater than or equal to 0.1 g/m ² , greater than or equal to or equal to 0.3g/m ² , greater than or equal to 0.5g/m ² , greater than or equal to 1g/m 2 , greater than or equal to 3g/m ^{2 ,} greater than or equal to 5g/m ² , greater than or equal to 6g/m ² , or Greater than or equal to 8g/m ² . In some embodiments, the basis weight of the fine fiber layer may be less than or equal to 10 g/m ² , less than or equal to 8 g/m 2 , less than or equal to 6 g/m ² , less than or equal to 5 g/m ² , ^less than or equal to 3 g/m 2 m ² , less than or equal to 1g/m ² , less than or equal to 0.5g/m ² , less than or equal to 0.3g/m ² , less than or equal to 0.1g/m ² , less than or equal to 0.05g/m ² , or less than or equal to Equal to 0.03 g/m ² . Combinations of the above-mentioned ranges are also possible (for example, greater than or equal to 0.01 g/m ² and less than or equal to 10 g/m ² , greater than or equal to 0.03 g/m ² and less than or equal to 10 g/m ² , or greater than or equal to equal to 0.01g/m ² and less than or equal to 5g/m ² ). Other ranges are also possible. The fixed weight can be determined according to the test standard ASTM D-846.

In certain embodiments, the fine fiber layer may have a specific air permeability. In some embodiments, the fine fiber layer has an air permeability greater than or equal to 10 CFM, greater than or equal to 25 CFM, greater than or equal to 50 CFM, greater than or equal to 80 CFM, greater than or equal to 100 CFM, greater than or equal to 200 CFM, greater than or equal to 250 CFM, greater than or equal to 300CFM, greater than or equal to 350CFM, greater than or equal to 400CFM, or greater than or equal to 450CFM. In certain embodiments, the fine fiber layer has an air permeability of less than or equal to 500 CFM, less than or equal to 450 CFM, less than or equal to 400 CFM, less than or equal to 350 CFM, less than or equal to 300 CFM, less than or equal to 250 CFM, less than or equal to 200 CFM, less than or equal to Equal to 150CFM, less than or equal to 100CFM, less than or equal to 80CFM, less than or equal to 50CFM, or less than or equal to 25CFM. Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 10 CFM and less than or equal to 500 CFM). Other ranges are also possible. As used herein, the air permeability of the second layer is measured according to test standard ASTM D737 on a media surface area of 38 cm ² and using a pressure of 125 Pa.

In an exemplary embodiment, a filter media includes an open support layer, an additional layer such as a meltblown or spunbond layer associated with the open support layer, and a charged fiber layer adjacent to the additional layer. In yet another exemplary embodiment, the filter media includes an open support layer, an additional layer such as a meltblown layer or a spunbond layer associated with the open support layer, and a fine fiber layer adjacent (e.g., directly adjacent) to the additional layer . In some such embodiments, the layer of charged fibers can be adjacent to (eg, directly adjacent to) the layer of fine fibers.

In some embodiments, the combined air permeability of the open support layer, additional layer (e.g., meltblown layer) and fine fiber layer can be greater than or equal to 10 CFM, greater than or equal to 20 CFM, greater than or equal to 40 CFM, greater than or equal to 60 CFM, greater than or equal to Equal to 80CFM, greater than or equal to 100CFM, greater than or equal to 150CFM, greater than or equal to 200CFM, greater than or equal to 250CFM, greater than or equal to 300CFM, greater than or equal to 350CFM, greater than or equal to 400CFM, or greater than or equal to 450CFM. In certain embodiments, the combined air permeability of the open support layer, additional layer (e.g., meltblown layer) and fine fiber layer is less than or equal to 500 CFM, less than or equal to 450 CFM, less than or equal to 400 CFM, less than or equal to 350 CFM, less than or equal to Equal to 300CFM, less than or equal to 250CFM, less than or equal to 200CFM, less than or equal to 150CFM, less than or equal to 100CFM, less than or equal to 80CFM, less than or equal to 60CFM, less than or equal to 40CFM, or less than or equal to 20CFM. Combinations of the ranges mentioned above are also possible (eg, greater than or equal to 10 CFM and less than or equal to 500 CFM). Other ranges are also possible.

The filter media may include any suitable number of open support layers, additional layers, and/or charged fiber layers, each of which may or may not be mechanically attached to each other. For example, in some embodiments, a filter media can include two open support layers disposed on two open support layers (e.g., a first open support layer upstream of and mechanically attached to a charged fiber layer, and The charged fiber layer between the second open support layer downstream and mechanically attached to the charged fiber layer). In certain embodiments, the filter media can include two charged fibrous layers disposed (e.g., a first charged fibrous layer upstream of and mechanically attached to the open support layer, and a first charged fibrous layer downstream of the open support layer). and mechanically attached to the open support layer between the second charged fiber layer). For example, referring again to FIG. 1B , in some embodiments, filter media 102 can include an open support layer disposed between a first charged layer (ie, second layer 120 ) and a second charged layer (ie, third layer 122 ). (ie first layer 110).

Any suitable number of charged fiber layers may be present in the filter media. In some embodiments, the filter media can include one or more, two or more, three or more, or four or more charged fibrous layers, one or more of which are mechanically Attaches to an open support layer. In certain embodiments, filter media may include five or fewer, four or fewer, three or fewer, or two fewer layers of charged fibers, one or more of which are mechanically ground to the open support layer. Combinations of the above mentioned ranges are also possible (eg 1 to 5 charged fiber layers). Other ranges are also possible.

Similarly, any suitable number of open support layers may be present in the filter media. In some embodiments, filter media can include one or more, two or more, three or more, or four or more open support layers, one or more of which are mechanically Attached to charged fiber layer. In certain embodiments, filter media can include five or fewer, four or fewer, three or fewer, or two fewer open support layers, one or more of which are mechanically ground attached to the charged fiber layer. Combinations of the ranges mentioned above are also possible (eg, 1 to 5 open support layers). Other ranges are also possible.

A filter media as described herein having a charged fiber layer mechanically attached to an open support layer can have desired structural properties, such as overall basis weight and/or overall thickness. In some embodiments, the filter media may have a total basis weight greater than or equal to 12 g/m ² , greater than or equal to 20 g/m ² , greater than or equal to 25 g/m ² , greater than or equal to 30 g/m ² , greater than or equal to 40 g/m 2 m ² , greater than or equal to 50g/m ² , greater than or equal to 60g/m ² , greater than or equal to 70g/m ² , greater than or equal to 80g/m ² , greater than 85g/m ² , greater than or equal to 90g/m ² , greater than Or equal to 100g/m ² , greater than or equal to 150g/m ² , greater than or equal to 200g/m ² g/m ² , greater than or equal to 250g/m ² , greater than or equal to 300g/m ² , greater than or equal to 350g/m ² , greater than or equal to 400g/m ² , greater than or equal to 450g/m ² , greater than or equal to 500g/m ² , greater than or equal to 550g/m ² , greater than or equal to 600g/m ² , greater than or equal to 650g/m ² , or Greater than or equal to 700g/m ² . In some embodiments, the filter media may have a total basis weight less than or equal to 750 g/m ² , less than or equal to 700 g/m ² , less than or equal to 650 g/m ² , less than or equal to 600 g/m ² , less than or equal to 550 g/m 2 m ² , less than or equal to 500g/m ² , less than or equal to 450g/m ² , less than or equal to 400g/m ² , less than or equal to 350g/m ² , less than or equal to 300g/m ² , less than or equal to 250g/m ² , less than or equal to 200g/m ² , less than or equal to 150g/m ² , less than or equal to 100g/m ² , less than or equal to 90g/m ² , less than or equal to 85g/m ² , less than or equal to 80g/m ² , less than or equal to 70g/m ² , less than or equal to 60g/m ² , less than or equal to 50g/m ² , less than or equal to 40g/m ² , less than or equal to 30g/m ² , less than or equal to 25g/m ² , or less than or equal to Equal to 20g/m ² . Combinations of the above-mentioned ranges are also possible (for example, total fixed weight greater than or equal to 12 g/m ² and less than or equal to 750 g/m ² , greater than or equal to 40 g/m ² and less than or equal to 700 g/m ² , greater than or equal to equal to 50g/m ² and less than or equal to 650g/m ² , greater than or equal to 25g/m ² and less than or equal to 650g/m ² ). Other values for the total deadweight are also possible. The total dead weight can be determined according to the test standard ASTM D-846.

In some embodiments, the total thickness of the filter media (e.g., filter media having a charged fiber layer mechanically attached to an open support layer, filter media comprising an open support layer and one or more additional layers) can be greater than or 5 mil or greater, 10 mil or greater, 15 mil or greater, 20 mil or greater, 30 mil or greater, 40 mil or greater, 50 mil or greater, or greater 100 mil, greater than or equal to 150 mil, greater than or equal to 200 mil, greater than or equal to 250 mil, greater than or equal to 300 mil, greater than or equal to 350 mil, greater than or equal to 400 mil, greater than or equal to 450 mil, 500 mil or greater, 550 mil or greater, 600 mil or greater, 700 mil or greater, 800 mil or greater, 900 mil or greater, 1000 mil or greater Lugs, 1200 mils or greater, 1400 mils or greater, 1600 mils or greater, or 1800 mils or greater. In certain embodiments, the filter media has a total thickness of 2000 mils or less, 1800 mils or less, 1600 mils or less, 1400 mils or less, 1200 mils or less, 1200 mils or less, or 1000 mils, 900 mils or less, 800 mils or less, 700 mils or less, 600 mils or less, 550 mils or less, 500 mils or less, 450 mils or less mil, 400 mil or less, 350 mil or less, 300 mil or less, 250 mil or less, 200 mil or less, 150 mil or less, 100 mil or less lug, 50 mils or less, 40 mils or less, 30 mils or less, 20 mils or less, 15 mils or less, or 10 mils or less. Combinations of the above mentioned ranges are also possible (e.g., total thickness greater than or equal to 5 mils and less than or equal to 600 mils, greater than or equal to 30 mils and less than or equal to 350 mils, greater than or equal to 5 mils and less than or equal to 2000 mils). Other values for the total thickness are also possible. The total thickness can be determined according to test standard ASTM D-1777.

A filter media as described herein having a charged fiber layer mechanically attached to an open support layer can have desired filtration properties such as gamma, normalized gamma, pressure drop, and/or total air permeability.

Filter media (eg, filter media comprising an open support layer mechanically attached to a charged fibrous layer, filter media comprising an open support layer and one or more additional layers) can exhibit suitable overall air permeability characteristics. In some embodiments, the filter media may have a total air permeability of about 30 CFM to about 1100 CFM. In some embodiments, the total air permeability of the filter media can be greater than or equal to 30 CFM, greater than or equal to 50 CFM, greater than or equal to 75 CFM, greater than or equal to 100 CFM, greater than or equal to 150 CFM, greater than or equal to 200 CFM, greater than or equal to 300 CFM, greater than or equal to Equal to 400CFM, greater than or equal to 500CFM, greater than or equal to 600CFM, greater than or equal to 700CFM, greater than or equal to 800CFM, greater than or equal to 900CFM, or greater than or equal to 1000CFM. In certain embodiments, the total air permeability of the filter media is less than or equal to 1100 CFM, less than or equal to 1000 CFM, less than or equal to 900 CFM, less than or equal to 800 CFM, less than or equal to 700 CFM, less than or equal to 600 CFM, less than or equal to 500 CFM, less than or equal to Equal to 400CFM, less than or equal to 300CFM, less than or equal to 200CFM, less than or equal to 100CFM, less than or equal to 75CFM, or less than or equal to 50CFM. Combinations of the ranges mentioned above are also possible (eg, air permeability greater than or equal to 30 CFM and less than or equal to 1100 CFM). Other ranges are also possible. As determined herein, the total air permeability of a filter media is measured according to test standard ASTM D737 on a media surface area of 38 cm ² and using a pressure of 125 Pa.

The pressure drop across a filter media (e.g., a filter media comprising an open support layer mechanically attached to a charged fiber layer, a filter media comprising an open support layer and one or more additional layers) may vary depending on the particular application of the filter media. Variety. For example, in some embodiments, the pressure drop across the filter media may be from 1 Pa to 120 Pa, or from 1 Pa to 100 Pa. In some embodiments, the pressure drop across the filter media may be greater than or equal to 1 Pa, greater than or equal to 2 Pa, greater than or equal to 5 Pa, greater than or equal to 10 Pa, greater than or equal to 20 Pa, greater than or equal to 30 Pa, greater than or equal to 40 Pa, greater than or equal to Equal to 50Pa, greater than or equal to 60Pa, greater than or equal to 70Pa, greater than or equal to 80Pa, greater than or equal to 90Pa, greater than or equal to 100Pa, or greater than or equal to 110Pa. In certain embodiments, the pressure drop across the filter media may be 120 Pa or less, 110 Pa or less, 100 Pa or less, 90 Pa or less, 80 Pa or less, 70 Pa or less, 60 Pa or less, Or equal to 50Pa, less than or equal to 40Pa, less than or equal to 30Pa, less than or equal to 20Pa, less than or equal to 10Pa, less than or equal to 5Pa, or less than or equal to 2Pa. Combinations of the ranges mentioned above are also possible (eg, pressure drop greater than or equal to 1 Pa and less than or equal to 120 Pa, greater than or equal to 1 Pa and less than or equal to 100 Pa). Other ranges are also possible.

Pressure drop is measured as the pressure differential across the filter media or fiber layer when exposed to NaCl aerosol at a face velocity of 95 liters per minute. Face velocity is the velocity of the air as it strikes the upstream side of the filter media or layer. Pressure drop values are usually reported in millimeters of water or Pascals. The pressure drop values described here are determined according to the EN13274-7 standard. The pressure drop values are measured over an area of 100 ^cm2 with a NaCl aerosol with a particle size of 0.65 μm at a face velocity of 95 liters/min.

In some embodiments, the filter media can have a desired normalized efficiency. For example, in some embodiments, the filter media can have a normalized efficiency of 1 or greater, 1.25 or greater, 1.5 or greater, 2 or greater, 2.5 or greater, or 3 or greater. In certain embodiments, the filter media can have a normalized efficiency of less than or equal to 3.5, less than or equal to 3, less than or equal to 2.5, less than or equal to 2, or less than or equal to 1.5. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 1 and less than or equal to 3.5). Other values for the normalized efficiency of the filter media are also possible. Normalized efficiency has no units and refers to the initial percent efficiency of the filter media compared to the total basis weight (in g /m ² measurement) ratio. The initial efficiency was determined according to the EN13274-7 standard using NaCl aerosol with a particle size of 0.65 μm at a face velocity of 95 L/min over an area of 100 ^cm2 .

Advantageously, comprising an open support layer mechanically attached (e.g., needling) to the charged fiber layer (e.g., air permeable) as compared to filter media having a support layer adjacent to the charged fiber layer with an air permeability of less than or equal to 1100 CFM Filter media with open support layers having rates greater than 1100 CFM) may exhibit reduced pressure drop and/or increased dust holding capacity.

In some embodiments, the filter media can have a certain dust holding capacity. For example, in some embodiments, the filter media can have a dust holding capacity greater than or equal to 1 g/m ² , greater than or equal to 5 g/m ² , greater than or equal to 10 g/m ² , greater than or equal to 20 g/m ² , greater than or equal to 30g/m ² , greater than or equal to 40g/m ² , greater than or equal to 50g/m ² , greater than or equal to 60g/m ² , greater than or equal to 70g/m ² , greater than or equal to 80g/m ² , greater than or equal to 90g/m 2 m ² , greater than or equal to 100 g/m ² , greater than or equal to 110 g/m ² , greater than or equal to 120 g/m ² , or greater than or equal to 130 g/m ² . In certain embodiments, the dust holding capacity of the filter media can be less than or equal to 140 g/m ² , less than or equal to 130 g/m ² , less than or equal to 120 g/m ² , less than or equal to 110 g/m ² , less than or equal to 100 g /m ² , less than or equal to 90g/m ² , less than or equal to 80g/m ² , less than or equal to 70g/m 2 , less than or equal to 60g/ ^{m 2 ,} less than or equal to 50g/m ² , less than or equal to 40g/m ² , less than or equal to 30g/m ² , less than or equal to 20g/m ² , less than or equal to 10g/m ² , or less than or equal to 5g/m ² . Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to about 1 g/m ² and less than or equal to about 140 g/m ² , greater than or equal to about 80 g/m ² and less than or equal to about 140 g/m ² ). Other values of dust holding capacity are also possible. The dust holding capacity of filter media in a non-corrugated configuration comprising an open support layer mechanically attached to a charged fiber layer was tested based on standard ISO/TS 11155-1. The test uses ISO 12103-1, A2 fine test dust with a base upstream gravity dust level of 75mg/ ^m3 . The test was carried out at a face velocity of 20 cm/sec over a filter area of 100 cm ² until the filter medium reached an air resistance of 82 Pa.

Since it may be desirable to rate filter media or layers based on the relationship between penetration and pressure drop across the media, or particulate efficiency as a function of pressure drop across the media or web, it can be based on what is known as the gamma value A value of to rate the filter. In general, higher gamma values indicate better filtration performance, ie high particulate efficiency as a function of pressure drop. The γ value is expressed according to the following formula: γ=(-log(initial NaCl penetration rate%/100)/pressure drop, Pa)×100×9.8, equivalent to: γ=(-log(initial NaCl penetration rate%/100 )/pressure drop, mm H ₂ O)×100.

The percent NaCl penetration is based on the percentage of particles passing through the filter media or layer. Gamma increases where the percent NaCl penetration decreases (ie, particle efficiency increases) (when particles are less able to pass through the filter media or layer). At reduced pressure drop (ie, low resistance to fluid flow through the filter), γ increases. These generalized relationships between NaCl breakthrough, pressure drop, and/or gamma assume that other properties remain constant.

The penetration rate (usually expressed as a percentage) is defined as follows: penetration rate (%)=(C/C ₀ )*100, where C is the particle concentration after passing through the filter, and C ₀ is the particle before passing through the filter concentration. A typical test for penetration involves blowing sodium chloride (NaCl) particles through a filter media or layer and measuring the percentage of particles that pass through the filter media or layer. Penetration and pressure drop values stated herein are based on the EN13274-7 standard for NaCl particles using an 8130 CertiTest ^™ automated filter test unit from TSI, Inc. equipped with a sodium chloride generator for NaCl aerosol testing Sure. The average particle size produced by the salt particle generator was 0.65 micron mass mean diameter. The instrument is based on instantaneous measurement of the pressure drop across the filter media and the resulting penetration values. Initial penetration is first obtained at the beginning of the test and can be used to determine the initial efficiency of the filter media. Pressure drop values (eg for determining gamma) are determined using the EN13274-7 standard on a sodium flame photometer from SFP Services Ltd, UK. This instrument measures the pressure drop across a filter media (or layer) when the filter media or layer is subjected to a face velocity of 95 liters per minute over an area of 100 ^cm2 .

Filter media (eg, filter media comprising an open support layer mechanically attached to a charged fiber layer, filter media comprising an open support layer and one or more additional layers) as a whole may have a relatively high gamma value. In some embodiments, the filter has a gamma value of 30 or greater, 50 or greater, 75 or greater, 100 or greater, 125 or greater, 150 or greater, 175 or greater, 200 or greater , or greater than or equal to 225. In some embodiments, the filter media has a gamma value of 250 or less, 225 or less, 200 or less, 175 or less, 150 or less, 125 or less, 100 or less, 75 or less , or less than or equal to 50. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 30 and less than or equal to 250, or greater than or equal to 75 and less than or equal to 150). Other ranges are also possible.

In some embodiments, the open support layer, one or more additional layers (eg, a meltblown layer), and the charged fiber layer can have a relatively high combined gamma value. In some embodiments, the combined gamma value of the open support layer, one or more additional layers, and the charged fibrous layer (e.g., measured for an open support layer associated with one or more additional layers and laminated to the charged fibrous layer γ value) greater than or equal to 1, greater than or equal to 5, greater than or equal to 10, greater than or equal to 20, greater than or equal to 30, greater than or equal to 50, greater than or equal to 75, greater than or equal to 90, greater than or equal to 100, greater than 125 or greater, 150 or greater, 175 or greater, 180 or greater, 200 or greater, or 225 or greater. In certain embodiments, the combined gamma value of the open support layer, one or more additional layers, and the charged fibrous layer is less than or equal to 250, less than or equal to 225, less than or equal to 200, less than or equal to 180, less than or equal to 175 , 150 or less, 125 or less, 100 or less, 90 or less, 75 or less, 50 or less, 30 or less, 20 or less, 10 or less, or 5. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 1 and less than or equal to 180, or greater than or equal to 90 and less than or equal to 180). Other ranges are also possible.

In a specific set of embodiments, the open support layer, additional layers such as meltblown layers, and charged fiber layers are laminated together and have a combined gamma value of 90 or greater and 180 or less. In some such embodiments, the meltblown layer can be hydrodynamically charged as described above. In some embodiments, the open support layer, additional layers, and/or charged fiber layers are maintained in a corrugated configuration and have a combined gamma value of 90 or greater and 250 or less. In certain embodiments, the open support layer, additional layers, and/or charged fiber layers are non-corrugated and have a combined gamma value of 90 or greater and 250 or less.

Filter media (e.g., filter media comprising an open support layer mechanically attached to a charged fiber layer, filter media comprising an open support layer associated with one or more additional layers and laminated to a charged fiber layer) may have desired The normalized γ of . As used herein, normalized γ is a unitless parameter and refers to the sum of γ of the filter media and one or more charged fiber layers (i.e., excluding any open or coarse support layers) within the filter media. Ratio of weight (measured in g/ ^m2 ). In some embodiments, the normalized gamma of the filter media (e.g., a filter media comprising an open support layer mechanically attached to a charged fiber layer) can be greater than or equal to 1, greater than or equal to 1.5, greater than or equal to 2, greater than or equal to 2.5, greater than or equal to 3, greater than or equal to 3.5, greater than or equal to 4, greater than or equal to 4.5, greater than or equal to 5, greater than or equal to 5.5, greater than or equal to 5.6, greater than or equal to 6, greater than or equal to, greater than or equal to 6.5 or greater, 7 or greater, 7.5 or greater, 8 or greater, 8.5 or greater, 9 or greater, 9.5 or greater, 10 or greater, or 10.5 or greater. In certain embodiments, the filter media may have a normalized gamma of 10.9 or less, 10.5 or less, 10 or less, 9.5 or less, 9 or less, 8.5 or less, 8 or less, 7.5 or less, 7 or less, 6.5 or less, 6 or less, 5.6 or less, 5.5 or less, 5 or less, 4.5 or less, 4 or less, 3.5 or less, 3 or less, 2.5 or less, 2 or less, or 1.5 or less. Combinations of the above-mentioned ranges are also possible (eg, normalized gamma of the filter media is greater than or equal to 1 and less than or equal to 10.9, greater than or equal to 1 and less than or equal to 5.6). Other ranges are also possible. For example, in an exemplary embodiment, the filter media includes a charged fiber layer comprising a plurality of fibers, and the filter media has a normalized gamma of greater than or equal to 1 and less than or equal to 5.6. In another exemplary embodiment, the filter media includes a multi-fiber charged fiber layer comprising relatively fine multi-fibers (e.g., an average fiber diameter of less than 15 microns), and the filter media has a The normalized γ of .

As described herein, filter media and/or layers (eg, first layer, second layer) can be designed to have a penetration or efficiency (eg, initial efficiency). Penetration and (initial) efficiency were measured as described above. Typically, (initial) efficiency is determined as 100-% penetration. The penetration rate expressed as a percentage is defined as the penetration rate=(C/C ₀ )*100, where C is the particle concentration after passing through the filter medium, and C0 is the particle concentration before passing through the filter medium.

In some embodiments, the filter media (e.g., comprising an open support layer, a charged fiber layer, one or more additional layers, and/or a fine fiber layer) has an initial efficiency of greater than or equal to 50%, greater than or equal to 55%, 60% or greater, 65% or greater, 70% or greater, 75% or greater, 80% or greater, 85% or greater, 90% or greater, 92% or greater, or 95% or greater, 96% or greater, 97% or greater, 98% or greater, 99% or greater, 99.5% or greater, 99.8% or greater, 99.9% or greater, or greater than or equal to 99.99%. In some embodiments, the filter media (e.g., comprising an open support layer, a charged fiber layer, one or more additional layers, and/or a fine fiber layer) has an initial efficiency of less than or equal to 99.999%, less than or equal to 99.99%, Less than or equal to 99.9%, Less than or equal to 99.8%, Less than or equal to 99.5%, Less than or equal to 99%, Less than or equal to 98%, Less than or equal to 97%, Less than or equal to 96%, Less than or equal to 95%, Less than or equal to 92% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, or 55%. Combinations of the ranges mentioned above are also possible (eg, initial efficiency greater than or equal to 50% and less than or equal to 99.999%, greater than or equal to 90% and less than or equal to 99.999%). Other ranges are also possible. Initial efficiencies were determined as described below.

In an exemplary embodiment, the filter media can include an open support layer having an air permeability greater than 1100 CFM and less than or equal to 20000 CFM and being a mesh, and a charged fiber layer mechanically attached to the open support layer. In some embodiments, the solidity of the open support layer is less than or equal to 10%.

In another exemplary embodiment, a filter media can include an open support layer and a charged fiber layer mechanically attached to the open support layer, wherein the open support layer has an air permeability greater than 1100 CFM and less than or equal to 20000 CFM. In some embodiments, the filter media has a total basis weight of greater than or equal to 12 g/m ² and less than or equal to 700 g/m ² , a gamma of greater than or equal to 90 and less than or equal to 250, and/or greater than or equal to 30 CFM and less than Or equal to a total air permeability of 1100CFM. In some cases, the charged fiber layer can be needle punched to the open support layer.

In some embodiments, a filter media can include at least one layer (eg, a layer of charged fibers) maintained in a wave or curvilinear configuration. In certain embodiments, the filter media (and/or one or more open support layers of the filter media) are held in a corrugated or curve configuration. Advantageously, due to the corrugated configuration, the filter medium may have an increased surface area, which may result in improved filter properties. The filter media may comprise multiple layers (e.g., an open support layer, one or more fibrous layers such as charged fiber layers, a coarse support layer, a top layer, and/or a bottom layer), and only some or all of the layers may be corrugated . Advantageously, a filter media as described herein having at least one layer maintained in a wave or curvilinear configuration may comprise a relatively charged fiber layer having a relatively low basis weight.

In some embodiments, an open support layer, such as a mesh, can provide additional mechanical reinforcement and/or structural stability while having a relatively high air permeability (eg, for filter media with a corrugated configuration). FIG. 2A shows an exemplary embodiment of a filter media 200 having a first layer 210 (e.g., an open support layer, such as a mesh) and a second layer 220 (e.g., a charged fiber layer) adjacent to the first layer 210. ). In the illustrated embodiment, the first layer 210 and the second layer 220 are a corrugated configuration comprising the peaks and troughs of adjacent waves of the filter media. As shown in FIG. 2B , in some embodiments, filter media 202 includes a first layer disposed between a second layer 220 (e.g., a first charged fiber layer) and a third layer 222 (e.g., a second charged fiber layer). Layer 210 (eg, an open support layer, such as a mesh).

In certain embodiments, the filter media includes a coarse support layer that maintains one or more layers (e.g., an open support layer, one or more additional layers, and/or charged fiber layers) in a corrugated configuration , to maintain the separation of the peaks and troughs of adjacent waves of one or more layers. As shown in FIG. 2C , the filter media 204 includes a first layer 210 (eg, an open layer) disposed between a second layer 220 (eg, a first charged fiber layer) and a third layer 230 (eg, a second charged fiber layer). supporting layer, such as mesh). In the illustrated embodiment, filter media 204 includes a first coarse support layer 230 adjacent to second layer 220 and a second coarse support layer 232 adjacent to third layer 222 . Coarse support layers 230 and 232 can help maintain second layer 220 and third layer 230, and optionally any additional layers (eg, open support layers), in a corrugated configuration. Although two coarse support layers 230, 232 are shown, the filter media 204 need not include two coarse support layers. Where only one support layer is provided, the support layer may be arranged upstream or downstream of the layer.

The filter media 204 may also optionally include one or more outer or cover layers located on the most upstream side and/or the most downstream side of the filter media 204 . FIG. 2C shows top layer 240 disposed on the upstream side of filter media 204 to serve as, for example, an upstream dust-containment layer and/or support layer. The top layer 240 can also serve as an aesthetic layer, which will be discussed in more detail below. The layers in the illustrated embodiment are arranged such that the top layer 240 is positioned on the air inlet side (labeled I), the first coarse support layer 230 is just downstream of the top layer 240, and the second fibrous layer 220 is positioned just above the first coarse support layer Downstream of 230, the open support layer 210 is arranged downstream of the second fiber layer 220, the third fiber layer 222 is arranged downstream of the open support layer 210, and the second coarse support layer 232 is arranged on the air outflow side (marked O) at the second Downstream of the tri-fiber layer 222 . The direction of air flow (ie, from air in I to air out O) is indicated by the arrow marked with reference A. The outer layer or cover layer may alternatively or additionally be a bottom layer disposed on the downstream side of the filter media 204 to serve as a reinforcing component for the filter media 204 to provide structural integrity to help maintain the corrugated configuration. The outer or cover layer may also function to provide abrasion resistance.

In certain embodiments, one or more additional layers (eg, meltblown layers) and associated open support layers and/or charged fiber layers are in a corrugated configuration. In some embodiments, one or more coarse support layers maintain one or more additional layers (e.g., meltblown layers) and associated open support layers and/or charged fiber layers in a corrugated configuration and maintain the phase of the layers. Separation of peaks and troughs of adjacent waves. In an exemplary embodiment, a filter media includes an open support layer, an additional layer (e.g., a meltblown layer) associated with the open support layer, and a charged fiber layer, wherein the additional layer, the open support layer, and the charged fiber layer are in a corrugated configuration . In some cases, the filter media includes a thin fiber layer that in some cases may be in a wave configuration (eg, the open support layer, the additional layer, the thin fiber layer, and the charged fiber layer are in a wave configuration).

Furthermore, as shown in the exemplary embodiment shown in Figure 2C, the topography of the outer or cover layer may be different from the topography of the fiber layer and/or any support layer. For example, in a pleated or non-pleated configuration, the outer layer or cover layer can be non-corrugated (eg, substantially planar), while the fibrous layer and/or any open support layer can have a corrugated configuration. Those skilled in the art will appreciate that numerous other configurations are possible, and that the filter media may include any number of layers in various arrangements.

As illustratively shown in FIGS. 2C to 2D , the fibrous layer and/or the support layer may have a corrugated configuration including a plurality of peaks P and valleys T relative to their respective surfaces. Those skilled in the art will appreciate that a peak P on one side of the fiber layer may have a corresponding valley T on the opposite side. Thus, the second layer 220 may extend into a valley T, and just opposite the same valley T is a peak P, across which the upstream third layer 222 may extend. As illustratively shown in Figure 2D, peaks and valleys may also exist within a single fiber layer. As illustratively shown in Figure 2C, the valleys may be partially or substantially filled with fibers (eg, partially or substantially filled with a coarse support layer).

Some or all of the fiber layers, and/or some or all of the support layers (e.g., an open support layer, one or more coarse support layers) can be formed into a wave-shaped configuration using a variety of fabrication techniques, but when a single fiber layer is involved In an exemplary embodiment of the present invention, the fiber layer is positioned on a first moving surface adjacent to the second moving surface, and the fiber layer is conveyed between the first moving surface and the second moving surface traveling at different speeds. In one example involving two or more fiber layers, the fiber layers are positioned adjacent to each other in a desired arrangement from the air inlet side to the air outlet side, and the combined layers are positioned on a first moving surface traveling at different speeds and Teleport between the second moving surface. For example, the second surface may travel at a slower speed than the first surface. In either arrangement, suction (eg vacuum) may be used to pull the layer towards the first moving surface and then towards the second moving surface as the layer travels from the first moving surface to the second moving surface. The velocity difference causes the layer to form Z-directed waves as it travels onto the second moving surface, forming peaks and valleys in the layer. The velocity of each surface as well as the velocity ratio between the two surfaces can be varied to obtain the percentage of fiber orientation as described herein. Generally, a higher velocity ratio results in a higher percentage of fibers having a more angular orientation relative to the horizontal plane or relative to the surface (eg, flat surface) of the fiber layer or outer layer or cover layer. In some embodiments, one or more fibrous layers or filter media are formed using a velocity ratio of at least 1.5, at least 2.5, at least 3.5, at least 4.0, at least 4.5, at least 5.0, at least 5.5, or at least 6.0. In certain embodiments, the speed ratio is 10.0 or less, 9.0 or less, 8.0 or less, 7.0 or less, 6.0 or less, 5.0 or less, or 4.0 or less, 3.5 or less, Less than or equal to 3.0, or less than or equal to 2.5. Combinations of the above mentioned ranges are also possible. Other ratios are also possible.

The velocity of each surface can also be varied to obtain the desired wave number per inch. The distance between the surfaces can also be varied to determine the magnitude of the peaks and valleys, in one exemplary embodiment the distance is adjusted from 0 to 2". The properties of the different layers can also be varied to obtain the desired filter media configuration.

In some embodiments, the period (e.g., waves per inch) of the second layer (e.g., charged fiber layer) can be from 3 waves/6 inches to 40 waves/6 inches (e.g., 3 waves/6 inches to 15 waves/6 inches, 5 waves/6 inches to 9 waves/6 inches, 10 waves/6 inches to 40 waves/6 inches). In some embodiments, the period of the fiber layer can be greater than or equal to 3 waves/6 inches, greater than or equal to 4 waves/6 inches, greater than or equal to 5 waves/6 inches, greater than or equal to 6 waves/6 inches , greater than or equal to 7 waves/6 inches, greater than or equal to 8 waves/6 inches, greater than or equal to 9 waves/6 inches, greater than or equal to 10 waves/6 inches, greater than or equal to 11 waves/6 inches , greater than or equal to 12 waves/6 inches, greater than or equal to 13 waves/6 inches, greater than or equal to 14 waves/6 inches, greater than or equal to 15 waves/6 inches, greater than or equal to 17 waves/6 inches , greater than or equal to 20 waves/6 inches, greater than or equal to 25 waves/6 inches, greater than or equal to 30 waves/6 inches, or greater than or equal to 35 waves/6 inches. In certain embodiments, the period of the second layer can be less than or equal to 40 waves/6 inches, less than or equal to 35 waves/6 inches, less than or equal to 30 waves/6 inches, less than or equal to 25 waves/6 inches 6 inches, less than or equal to 20 waves/6 inches, less than or equal to 17 waves/6 inches, less than or equal to 15 waves/6 inches, less than or equal to 14 waves/6 inches, less than or equal to 13 waves/ 6 inches, less than or equal to 12 waves/6 inches, less than or equal to 11 waves/6 inches, less than or equal to 10 waves/6 inches, less than or equal to 9 waves/6 inches, less than or equal to 8 waves/ 6 inches, less than or equal to 7 waves/6 inches, less than or equal to 6 waves/6 inches, less than or equal to 5 waves/6 inches, or less than or equal to 4 waves/6 inches. Combinations of the ranges mentioned above are also possible (e.g., the period of the second layer is greater than or equal to 10 waves/6 inches and less than or equal to 40 waves/6 inches, greater than or equal to 5 waves/6 inches and less than or equal to equal to 9 waves/6 inches, greater than or equal to 3 waves/6 inches and less than or equal to 15 waves/6 inches). Other ranges of periods are also possible. Furthermore, in embodiments where one or more layers (e.g., a third layer, such as a second charged fiber layer) are present in the medium, the period of each layer may have one or more of the above-mentioned ranges .

Any suitable number of charged fiber layers may be present in a filter media (eg, a filter media comprising an open support layer and one or more charged fiber layers, wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration). In some embodiments, the filter media can include one or more, two or more, three or more, or four or more charged fibrous layers, one or more of which are mechanically Attaches to an open support layer. In certain embodiments, filter media may include five or fewer, four or fewer, three or fewer, or two fewer layers of charged fibers, one or more of which are mechanically ground to the open support layer. Combinations of the above mentioned ranges are also possible (eg 1 to 5 charged fiber layers). Other ranges are also possible.

Similarly, any suitable number of open support layers may be present in the filter media. In some embodiments, filter media can include one or more, two or more, three or more, or four or more open support layers, one or more of which are mechanically Attached to charged fiber layer. In certain embodiments, filter media can include five or fewer, four or fewer, three or fewer, or two fewer open support layers, one or more of which are mechanically ground attached to the charged fiber layer. Combinations of the above mentioned ranges are also possible (eg 1 to 5 charged fiber layers). Other ranges are also possible.

A filter media as described herein having an open support layer, a coarse support layer, and a charged fiber layer (wherein at least the charged fiber layer is maintained in a wave or curvilinear configuration) can have desired structural properties, such as overall basis weight. In some embodiments, the total basis weight of the filter media can be greater than or equal to 30 g/m ² , greater than or equal to 40 g/m ² , greater than or equal to 50 g/m ² , greater than or equal to 60 g/m ² , greater than or equal to 70 g/m ² , greater than or equal to 80g/m ² , greater than 85g/m ² , greater than or equal to 90g/m ² , greater than or equal to 100g/m ² , greater than or equal to 150g/m ² greater than or equal to 200g/m ² g/m ² , greater than or equal to 250g/m ² , greater than or equal to 300g/m ² , greater than or equal to 350g/m ² , greater than or equal to 400g/m ² , greater than or equal to 450g/m ² , greater than or equal to 500g/m ² , greater than Or equal to 550g/m ² , greater than or equal to 600g/m ² , greater than or equal to 650g/m ² , greater than or equal to 700g/m ² , or greater than or equal to 750g/m ² . In some embodiments, the filter media can have a total basis weight less than or equal to 800 g/m ² , less than or equal to 750 g/m ² , less than or equal to 700 g/m ² , less than or equal to 650 g/m ² , less than or equal to 600 g/m 2 m ² , less than or equal to 550g/m ² , less than or equal to 500g/m ² , less than or equal to 450g/m ² , less than or equal to 400g/m ² , less than or equal to 350g/m ² , less than or equal to 300g/m ² , less than or equal to 250g/m ² , less than or equal to 200g/m ² , less than or equal to 150g/m ² , less than or equal to 100g/m ² , less than or equal to 90g/m ² , less than or equal to 85g/m ² , less than Or equal to 80g/m ² , less than or equal to 70g/m ² , less than or equal to 60g/m ² , less than or equal to 50g/m ² , or less than or equal to 40g/m ² . Combinations of the above-mentioned ranges are also possible (eg, total rated weight greater than or equal to 30 g/m ² and less than or equal to 800 g/m ² , greater than or equal to 100 g/m ² and less than or equal to 450 g/m ² ). Other values for the total deadweight are also possible. Total dead weight can be determined according to test standard ASTM D-846.

In some embodiments, a filter medium (e.g., a filter medium comprising an open support layer, a coarse support layer, and one or more charged fiber layers (wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration) has a specific thickness . In certain embodiments, the overall filter media has a thickness of 100 mils or more, 150 mils or more, 200 mils or more, 250 mils or more, 300 mils or more, 300 mils or more, 400 mils, greater than or equal to 500 mils, greater than or equal to 600 mils, greater than or equal to 700 mils, greater than or equal to 800 mils, greater than or equal to 900 mils, greater than or equal to 1000 mils, greater than or equal to 1500 mils mils, greater than or equal to 2000 mils, greater than or equal to 2500 mils, greater than or equal to 3000 mils, or greater than or equal to 3500 mils. In some embodiments, the overall filter media has a thickness of 4000 mils or less, 3500 mils or less, 3000 mils or less, 2500 mils or less, 2000 mils or less, 1500 mils or less mil, less than or equal to 1000 mil, less than or equal to 900 mil, less than or equal to 800 mil, less than or equal to 700 mil, less than or equal to 600 mil, less than or equal to 500 mil, less than or equal to 400 mil lug, 300 mils or less, 250 mils or less, 200 mils or less, or 150 mils or less. Combinations of the ranges mentioned above are also possible (eg, thickness greater than or equal to 100 mils and less than or equal to 4000 mils, greater than 150 mils and less than or equal to 1000 mils). Other ranges are also possible. The thickness of the overall filter media as determined herein is measured according to TAPPI T411.

A filter media as described herein having an open support layer, a coarse support layer, and one or more charged fiber layers wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration can have desirable filtration properties, such as dust holding capacity , γ, pressure drop and/or total air permeability.

Filter media (eg, filter media comprising an open support layer, a coarse support layer, and one or more charged fiber layers, wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration) can exhibit suitable overall air permeability characteristics. In some embodiments, the filter media may have a total air permeability of about 10 CFM to about 1000 CFM. In some embodiments, the total air permeability of the filter media can be greater than or equal to 10 CFM, greater than or equal to 25 CFM, greater than or equal to 50 CFM, greater than or equal to 75 CFM, greater than or equal to 100 CFM, greater than or equal to 150 CFM, greater than or equal to 200 CFM, greater than or equal to Equal to 300CFM, greater than or equal to 400CFM, greater than or equal to 500CFM, greater than or equal to 600CFM, greater than or equal to 700CFM, greater than or equal to 800CFM, or greater than or equal to 900CFM. In certain embodiments, the total air permeability of the filter media is less than or equal to 1000 CFM, less than or equal to 900 CFM, less than or equal to 800 CFM, less than or equal to 700 CFM, less than or equal to 600 CFM, less than or equal to 500 CFM, less than or equal to 400 CFM, less than or equal to Equal to 300CFM, less than or equal to 200CFM, less than or equal to 100CFM, less than or equal to 75CFM, less than or equal to 50CFM, or less than or equal to 25CFM. Combinations of the ranges mentioned above are also possible (eg, air permeability greater than or equal to 10 CFM and less than or equal to 1000 CFM, greater than or equal to 100 CFM and less than or equal to 700 CFM). Other ranges are also possible. The total air permeability of a filter media as determined herein is measured according to test standard ASTM D737 on a media surface area of 38 cm ² and using a pressure of 125 Pa.

The pressure drop across a filter media (e.g., a filter media comprising an open support layer, a coarse support layer, and one or more charged fiber layers (wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration)) can be determined according to the specific characteristics of the filter media. application varies. For example, in some embodiments, the pressure drop across the filter media may be from 2 Pa to 200 Pa, or from 3 Pa to 25 Pa. In some embodiments, the pressure drop across the filter media may be 2 Pa or greater, 3 Pa or greater, 5 Pa or greater, 10 Pa or greater, 20 Pa or greater, 25 Pa or greater, 50 Pa or greater, or Equal to 75Pa, greater than or equal to 100Pa, greater than or equal to 125Pa, greater than or equal to 150Pa, or greater than or equal to 175Pa. In certain embodiments, the pressure drop across the filter media may be 200 Pa or less, 175 Pa or less, 150 Pa or less, 125 Pa or less, 100 Pa or less, 75 Pa or less, 50 Pa or less, Or equal to 25Pa, less than or equal to 20Pa, less than or equal to 10Pa, less than or equal to 5Pa, or less than or equal to 3Pa. Combinations of the ranges mentioned above are also possible (eg, pressure drop greater than or equal to 2 Pa and less than or equal to 200 Pa, greater than or equal to 3 Pa and less than or equal to 25 Pa). Other ranges are also possible.

The filter media described herein can have beneficial dust holding properties. In some embodiments, the dust holding capacity of a filter medium (e.g., a filter medium comprising an open support layer, a coarse support layer, and one or more charged fiber layers (wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration) (DHC) can be greater than or equal to 5g/m ² , greater than or equal to 10g/m ² , greater than or equal to 25g/m ² , greater than or equal to 50g/m ² , greater than or equal to 75g/m ² , greater than or equal to 100g/m ² , greater than or equal to 150g/m ² , greater than or equal to 200g/m ² , greater than or equal to 250g/m ² , greater than or equal to 300g/m ² , greater than or equal to 350g/m ² , greater than or equal to 400g/m ² , 450 g/m ² or more, 500 g/m ² or more, or 550 g/m ² or more. In some embodiments, the DHC of the filter media can be less than or equal to 600 g/m ² , less than or equal to 550 g/m ² , less than or equal to 500 g/m ² , less than or equal to 450 g/m ² , less than or equal to 400 g/m ² , less than or equal to 350g/m ² , less than or equal to 300g/m ² , less than or equal to 250g/m ² , less than or equal to 200g/m ² , less than or equal to 150g/m ² , less than or equal to 100g/m ² , less than Or equal to 75g/m ² , less than or equal to 50g/m ² , less than or equal to 25g/m ² , or less than or equal to 10g/m ² . Combinations of the above mentioned ranges are also possible (eg DHC greater than or equal to 5 g/m ² and less than or equal to 600 g/m ² , greater than or equal to 200 g/m ² and less than or equal to 350 g/m ² ). Other ranges are also possible.

The dust holding capacity of filter media comprising an open support layer, a coarse support layer, and one or more charged fiber layers (wherein at least one charged fiber layer is maintained in a wave or curved configuration) is tested based on the ASHRAE 52.2 standard. This test uses ASHRAE test dust with a base upstream gravity dust level of 70mg/ ^m2 . The test was performed at a face velocity of 0.944 m ³ /sec (3400 m ³ /hour) to an end pressure of 450 Pa.

A filter media (eg, a filter media comprising an open support layer and one or more charged fiber layers wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration) as a whole can have a relatively high gamma value. In some embodiments, the filter has a gamma value of 20 or greater, 30 or greater, 50 or greater, 75 or greater, 100 or greater, 125 or greater, 150 or greater, 175 or greater , greater than or equal to 200, or greater than or equal to 225. In some embodiments, the filter media has a gamma value of 250 or less, 225 or less, 200 or less, 175 or less, 150 or less, 125 or less, 100 or less, 75 or less , less than or equal to 50, or less than or equal to 30. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 20 and less than or equal to 250, or greater than or equal to 75 and less than or equal to 150). Other ranges are also possible.

A filter media (e.g., a filter media comprising an open support layer, a coarse support layer, and one or more charged fiber layers wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration) can be designed to have a particular initial efficiency ( For example, initial efficiency).

In some embodiments, the initial efficiency of a filter medium (eg, a filter medium comprising an open support layer, a coarse support layer, and one or more charged fiber layers wherein at least one charged fiber layer is maintained in a wave or curvilinear configuration) is greater than 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 85% or more 90%, greater than or equal to 92%, greater than or equal to 95%, greater than or equal to 96%, greater than or equal to 97%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5%, greater than or equal to 99.8% , greater than or equal to 99.9%, or greater than or equal to 99.99%. In some embodiments, the initial efficiency of the filter media is less than or equal to 99.999%, less than or equal to 99.99%, less than or equal to 99.9%, less than or equal to 99.8%, less than or equal to 99.5%, less than or equal to 99%, less than or equal to 98%, less than or equal to 97%, less than or equal to 96%, less than or equal to 95%, less than or equal to 92%, less than or equal to 90%, less than or equal to 85%, less than or equal to 80%, less than or equal to 75% , 70% or less, 65% or less, 60% or less, or 55% or less. Combinations of the ranges mentioned above are also possible (eg, initial efficiency greater than or equal to 50% and less than or equal to 99.999%, greater than or equal to 90% and less than or equal to 99.999%). Other ranges are also possible.

In an exemplary embodiment, the filter media includes a charged fiber layer, an open support layer mechanically attached to the charged fiber layer, and the peaks and valleys of adjacent waves that maintain the charged fiber layer in a wave-shaped configuration and maintain the charged fiber layer separate coarse support layer. In some embodiments, the charged fibrous layer has a basis weight less than or equal to 12 g/m ² and greater than or equal to 700 g/m ² . In certain embodiments, the air permeability of the open support layer is greater than 1100 CFM and less than or equal to 20000 CFM. In some embodiments, the filter media has a total air permeability of greater than or equal to 10 CFM and less than or equal to 1000 CFM.

As described above and herein, in some embodiments, the filter media includes one or more coarse support layers (e.g., to maintain the charged fiber layers in a wave-shaped configuration and maintain the separation of the peaks and troughs of adjacent waves of the charged fiber layers ).

Referring again to FIG. 2C, the coarse support layers 230, 232 may be formed from a variety of fiber types and sizes. In an exemplary embodiment, downstream coarse support layer 232 is composed of an average fiber diameter greater than or equal to the average fiber diameter of second layer 220 and/or third layer 222, upstream coarse support layer 230, and top layer 240 (if provided). fiber formation. In some cases, upstream support layer 230 is formed from fibers having an average fiber diameter less than or equal to the average fiber diameter of downstream support layer 232 but greater than the average fiber diameter of second layer 220 and/or third layer 222 .

The fibers of the coarse support layer (eg, downstream support layer, upstream support layer) can have an average fiber length of, for example, about 0.5 inches to 6.0 inches (eg, 1.5 inches to 3 inches). In some embodiments, the average fiber length of the fibers of the coarse support layer can be less than or equal to 6 inches, less than or equal to 5.5 inches, less than or equal to 5 inches, less than or equal to 4.5 inches, less than or equal to 4 inches, less than or equal to 3.5 inches. inches, less than or equal to 3 inches, less than or equal to 2.5 inches, less than or equal to 2 inches, or less than or equal to 1 inch. In certain embodiments, the fibers of the coarse support layer can have an average fiber length of 0.5 inches or more, 1 inch or more, 1.5 inches or more, 2 inches or more, 2.5 inches or more, or 2.5 inches or more. 3 inches, greater than or equal to 3.5 inches, greater than or equal to 4 inches, greater than or equal to 4.5 inches, greater than or equal to 5 inches, or greater than or equal to 5.5 inches. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 0.5 inches and less than or equal to 6 inches, greater than or equal to 1.5 inches and less than or equal to 3 inches). Other ranges are also possible.

In some embodiments, the average fiber diameter of the plurality of fibers in the coarse support layer can be greater than or equal to 8 microns, greater than or equal to 10 microns, greater than or equal to 12 microns, greater than or equal to 15 microns, greater than or equal to 20 microns, greater than or equal to 25 microns or more, 30 microns or more, 35 microns or more, 40 microns or more, 45 microns or more, 50 microns or more, 55 microns or more, 60 microns or more, or 60 microns or more 65 microns, greater than or equal to 70 microns, greater than or equal to 75 microns, or greater than or equal to 80 microns. In some embodiments, the average fiber diameter of the plurality of fibers in the coarse support layer can be less than or equal to 85 microns, less than or equal to 80 microns, less than or equal to 75 microns, less than or equal to 70 microns, less than or equal to 65 microns, less than or equal to or equal to 60 microns, less than or equal to 55 microns, less than or equal to 50 microns, less than or equal to 45 microns, less than or equal to 40 microns, less than or equal to 35 microns, less than or equal to 30 microns, less than or equal to 25 microns, less than or equal to 20 microns, less than or equal to 15 microns, less than or equal to 12 microns, or less than or equal to 10 microns. Combinations of the above mentioned ranges are also possible (eg, greater than or equal to 8 microns and less than or equal to 85 microns, greater than or equal to 12 microns and less than or equal to 60 microns). Other values for the average fiber diameter of the coarse support layer are also possible.

A variety of materials can also be used for the fibers forming the coarse support layer, including synthetic and non-synthetic materials. In an exemplary embodiment, the coarse support layer is formed from staple fibers, in particular a combination of binder fibers and non-binder fibers. The binder fibers may be formed from any material that is effective in promoting thermal bonding between layers and thus has a lower activation temperature than the melting temperature of non-binder fibers. The binder fibers may be any of monocomponent fibers or a plurality of bicomponent binder fibers. In one embodiment, the binder fiber can be a bicomponent fiber, and each component can have a different melting temperature. For example, a binder fiber may comprise a core and a sheath, where the sheath has an activation temperature lower than the melting temperature of the core. This allows the sheath to melt before the core so that the sheath bonds with the other fibers in the layer while the core maintains its structural integrity. This can be particularly advantageous as it creates a more cohesive layer for trapping filtrate. The core/sheath binder fibers can be coaxial or non-coaxial, exemplary core/sheath binder fibers can include the following: polyester core/copolyester sheath, polyester core/polyethylene sheath, polyester core /polypropylene sheath, polypropylene core/polyethylene sheath, polyamide core/polyethylene sheath, and combinations thereof. Other exemplary bicomponent binder fibers may include split fiber fibers, side-by-side fibers, and/or "islands-in-the-sea" fibers.

The non-binder fibers may be synthetic and/or non-synthetic, and in an exemplary embodiment, the non-binder fibers may be about 100% synthetic. In general, synthetic fibers are preferred over non-synthetic fibers for resistance to moisture, heat, long-term aging, and microbial degradation. Exemplary synthetic non-binder fibers may include polyester, acrylic, polyolefin, nylon, rayon, and combinations thereof. Alternatively, the non-binder fibers used to form the coarse support layer may include non-synthetic fibers such as glass fibers, glass wool fibers, cellulose pulp fibers (eg, wood pulp fibers), and combinations thereof.

Non-limiting examples of suitable synthetic fibers include polyester, polyaramid, polyimide, polyolefin (e.g., polyethylene), polypropylene, Kevlar, Nomex, halogenated Polymers (eg, polyethylene terephthalate), acrylics, polyphenylene oxides, polyphenylene sulfides, polymethylpentenes, and combinations thereof. The coarse support layer can also be formed using a variety of techniques known in the art, including meltblowing, wet-laid techniques, air-laid techniques, carding, and spunbond. However, in an exemplary embodiment, the coarse support layer is a carded or airlaid web. The resulting layer can also have a variety of thicknesses, air permeability, and basis weights, depending on the requirements of the desired application. In an exemplary embodiment, the downstream coarse support layer and the upstream coarse support layer each have a thickness of 2 mils to 1000 mils (e.g., 12 mils to 100 mils) and a thickness of 5 g/m2 as measured in a planar configuration ^. A basis weight of up to 100 g/m ² (eg, 12 g/m ² to 40 g/m ² ).

For example, in some embodiments, one or more coarse support layers have a thickness of 2 mils or more, 3 mils or more, 5 mils or more, 10 mils or more, 12 mils or more mil, 15 mil or greater, 25 mil or greater, 50 mil or greater, 75 mil or greater, 100 mil or greater, 150 mil or greater, 200 mil or greater Lug, 250 mil or greater, 300 mil or greater, 400 mil or greater, 500 mil or greater, 600 mil or greater, 700 mil or greater, 800 mil or greater , or greater than or equal to 900 mils. In certain embodiments, the thickness of the one or more coarse support layers is 1000 mils or less, 900 mils or less, 800 mils or less, 700 mils or less, 600 mils or less Lug, 500 mil or less, 400 mil or less, 300 mil or less, 250 mil or less, 200 mil or less, 150 mil or less, 100 mil or less , 75 mils or less, 50 mils or less, 25 mils or less, 15 mils or less, 12 mils or less, 10 mils or less, 5 mils or less, Or less than or equal to 3 mils. Combinations of the ranges mentioned above are also possible (eg, thickness greater than or equal to 2 mils and less than or equal to 1000 mils, greater than or equal to 12 mils and less than or equal to 100 mils). Other ranges are also possible.

In some cases, the respective basis weights of the coarse support layers may be less than or equal to 100 g/m ² , less than or equal to 90 g/m ² , less than or equal to 85 g/m ² , less than or equal to 80 g/m ² , less than or equal to 70 g/m 2 m ² , less than or equal to 60g/m ² , less than or equal to 50g/m ² , less than or equal to 40g/m ² , less than or equal to 30g/m ² , less than or equal to 25g/m ² , less than or equal to 12g/m ² , or less than or equal to 10g/m ² . In some embodiments, the basis weight of the coarse support layer may be greater than or equal to 5 g/m ² , greater than or equal to 10 g/m ² , greater than or equal to 12 g/m ² , greater than or equal to 25 g/m ² , greater than or equal to 30 g/m 2 m ² , greater than or equal to 40g/m ² , greater than or equal to 50g/m ² , greater than or equal to 60g/m ² , greater than or equal to 70g/m ² , greater than or equal to 80g/m ² , greater than 85g/m ² , or Greater than or equal to 90g/m ² . Combinations of the above mentioned ranges are also possible (eg basis weight less than or equal to 100 g/m ² and greater than or equal to 5 g/m ² , basis weight less than or equal to 40 g/m ² and greater than or equal to 12 g/m ² ). Other values of fixed weight are also possible.

In some embodiments, the filter media may also optionally include one or more outer or cover layers (e.g., top layer, bottom layer). The cover layer may serve as a dust holding layer and/or it may serve as an aesthetic layer and/or a support layer. In an exemplary embodiment, the cover layer is a planar layer mated to the filter media after corrugating the charged fiber layer and optionally other layers. Thus, the cover layer provides an aesthetically pleasing top surface. The cover layer can be formed from a variety of fiber types and sizes, but in one exemplary embodiment, the cover layer is formed from fibers whose average fiber diameter is smaller than the average fiber diameter of the coarse support layer directly adjacent to the cover layer, but Greater than the average fiber diameter of the charged fiber layer (eg, second layer). In certain exemplary embodiments, the cover layer is formed from fibers having an average fiber diameter of about 5 μm to 20 μm.

In certain embodiments, the filter media described herein (or any given layer, eg, open support layer, charged fiber layer, one or more additional layers) may in some cases be antimicrobial. For example, the filter media (or any given layer) may contain multiple antimicrobial fibers. Such filter media may be used, for example, to prevent the growth of microorganisms (eg, bacteria, fungi, viruses) on one or more components (eg, fibers, layers) or filter media.

The filter media described herein (or any given layer, eg, open support layer, charged fiber layer, one or more additional layers) may in some cases be oleophobic. For example, filter media (or any given layer) can be tailored to have a specific level of oil repellency. Such filter media may be used, for example, to remove or coalesce oil, lubricants, and/or coolants from a gas stream passing through the filter media. In some embodiments, the filter medium or layer has an oil repellency level of 1 to 7 (eg, 1 to 4, 2 to 5, 3 to 6, 4 to 7). In some embodiments, the oil repellency level of the filter medium or layer is greater than or equal to 1. In certain embodiments, the filter medium or layer or sublayer has an oil repellency level of 1, 2, 3, 4, 5, 6, or 7. Oil repellency levels as described herein are determined according to AATCC™ 118 (1997) measured at 23°C and 50% relative humidity (RH). Briefly, 5 drops of each test oil (with an average droplet diameter of about 2mm) were placed at five different locations on the surface of the filter media or layer or sublayer. Test oil having a maximum oil surface tension that does not wet (i.e., has a contact angle with the surface greater than or equal to 90 degrees) the surface of the filter medium or layer or sublayer after contact with the filter medium for 30 seconds at 23°C and 50% RH Corresponds to oil repellency levels (listed in Table 2). For example, if a test oil with a surface tension of 26.6 mN/m does not wet (i.e., has a contact angle with the surface greater than or equal to 90 degrees) the surface of a filter medium or layer or sub-layer after 30 seconds with a surface tension of 25.4 mN The oil repellency level of the filter medium or layer or sublayer is 4 if the test oil/m wets the surface of the filter medium or layer or sublayer within thirty seconds. As another example, if a test oil with a surface tension of 25.4 mN/m does not wet the surface of the filter medium or layer or sublayer after 30 seconds, whereas a test oil with a surface tension of 23.8 mN/m does within thirty seconds wet the surface of the filter medium or layer or sublayer, the filter medium or layer or sublayer has an oil repellency level of 5. As yet another example, if a test oil with a surface tension of 23.8 mN/m does not wet the surface of the filter medium or layer or sub-layer after 30 seconds, whereas a test oil with a surface tension of 21.6 mN/m does within thirty seconds wet the surface of the filter medium or layer or sublayer, the filter medium or layer or sublayer has an oil repellency level of 6. In some embodiments, if three or more of five droplets in a given test partially wet the surface (e.g., form droplets on the surface but are not perfectly round), the level of oil repellency indicates To the nearest 0.5 value, the value is determined by subtracting 0.5 from the value of the test liquid. For example, if a test oil with a surface tension of 25.4 mN/m does not wet the surface of the filter medium or layer or sub-layer after 30 seconds, a test oil with a surface tension of 23.8 mN/m does not wet the surface of the filter medium or layer or sub-layer after 30 seconds only partially wet the surface of the filter medium or layer or sublayer within seconds (e.g. three or more test droplets forming not very round droplets on the surface of the filter medium or layer or sublayer) , then the oil repellency level of the filter medium or layer or sublayer is 5.5.

Table 2

Oil repellency level test oil Surface tension (in mN/m) 1 Kaydol (mineral oil) 31 2 65/35Kaydol/n-hexadecane 28 3 n-hexadecane 27.5 4 Tetradecane 26.6 5 n-dodecane 25.4 6 n-decane 23.8 7 n-octane 21.6 8 n-heptane 20.1

As noted above, in some embodiments, at least one surface of a layer (e.g., open support layer, additional layer) and/or at least one surface of the filter medium can be modified such that the filter medium has an oil repellency level of greater than or equal to 1. In some embodiments, a filter media can have at least one modified surface. In some embodiments, the filter media comprises a plurality of fibers, wherein at least a portion of the fibers comprise a modified surface. Materials for modifying at least one surface of the filter media and/or fibers may be applied to any suitable portion of the filter media. In some embodiments, the material can be applied such that one or more surfaces of the filter media are modified without substantially modifying the interior of the filter media. In some cases, individual surfaces of the filter media may be modified. For example, the upstream surface of the filter media may be coated. In other cases, more than one surface of a filter media (eg, an upstream surface and a downstream surface) may be coated. In other embodiments, at least a portion of the interior of the filter media and at least one surface of the filter media can be modified. In some embodiments, the entire filter media is modified with the material.

In general, any suitable method may be used to alter the surface chemistry of the plurality of fibers and/or at least one surface of the filter media (e.g., to alter the level of oil repellency of the filter media (or one or more layers of the filter media)) . In some embodiments, the surface chemistry of the plurality of fibers and/or filter media can be altered by coating at least a portion of the surface with a melt additive and/or altering the roughness of the surface.

In some embodiments, the surface modification can be a coating. Such coatings can be used to alter the level of oil repellency of the filter media (or one or more layers of the filter media). In certain embodiments, the coating process involves introducing a resin or material (e.g., hydrophobic material, hydrophilic material, lipophilic material, lipophobic material) dispersed in a solvent or solvent mixture into a preformed fiber layer (e.g., pre-formed filter media formed by the meltblown process). Non-limiting examples of coating methods include the use of chemical vapor deposition, slot die coater, gravure coating, screen coating, size press coating (e.g., two-roll or metered blade application) rubber press coater), film press coating, blade coating, roll knife coating, air knife coating, roll coating, foam application, reverse roll coating, rod coating, curtain coating, champlex coating, brush coating, bill blade coating, short dwell-blade coating, 1ip coating, gate roll coating, gate roll size press coating, laboratory size press coating, melt coating, dip coating, knife roll coating, spin coating, spray coating, notched roll coating, roll transfer coating, pad saturation coating and saturation dipping. Other coating methods are also possible. In some embodiments, the hydrophilic, hydrophobic, lipophilic, and/or lipophobic materials can be applied to the filter media using non-compressive coating techniques. Non-compressive coating techniques can coat filter media without substantially reducing the thickness of the web. In other embodiments, the resin may be applied to the filter media using compression coating techniques.

In one set of embodiments, chemical vapor deposition is used to modify the surfaces described herein (eg, to alter the level of oil repellency of the filter media (or one or more layers of the filter media)). In chemical vapor deposition, a filter medium is exposed to a gaseous reactant from a gas or liquid vapor under high energy level excitation such as heat, microwave, UV, electron beam or plasma, which deposits onto the filter medium . Optionally, carrier gases such as oxygen, helium, argon and/or nitrogen may be used.

Other vapor deposition methods include Atmospheric Pressure Chemical Vapor Deposition (APCVD), Low Pressure Chemical Vapor Deposition (LPCVD), Metal Organic Chemical Vapor Deposition (MOCVD), Plasma Assisted Chemical Vapor Deposition (PACVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD) , Laser Chemical Vapor Deposition (LCVD), Photochemical Vapor Deposition (PCVD), Chemical Vapor Infiltration (CVI) and Chemical Beam Epitaxy (CBE).

In physical vapor deposition (PVD), thin films are deposited by condensing the desired film material in evaporated form onto a substrate. The method involves physical processes such as high temperature vacuum evaporation followed by condensation, or plasma sputter bombardment rather than chemical reactions.

After applying the coating to the filter media, the coating can be dried by any suitable method. Non-limiting examples of drying methods include the use of photo dryers, infrared dryers, hot air oven steam heated cylinders, or any suitable type of dryer known to those of ordinary skill in the art.

In some embodiments, at least a portion of the fibers of the filter media can be coated without substantially clogging the pores of the filter media. In some cases, substantially all of the fibers can be coated without substantially clogging the pores. In some embodiments, filter media can be coated with a relatively high weight percent resin or material using the methods described herein (e.g., by dissolving and/or suspending one or more materials in a solvent to form a resin) without clogging the pores of the filter media.

In some embodiments, melt additives may be used to modify the surface (eg, to alter the level of oil repellency of the filter media (or one or more layers of the filter media)). Melt additives are functional chemicals added to thermoplastic fibers during the extrusion process that can make the physical and chemical properties at the surface after forming different from those of the thermoplastic itself.

In some embodiments, the material can undergo a chemical reaction (eg, polymerize) after being applied to the filter media. For example, the surface of the filter media can be coated with one or more monomers that can polymerize after coating. In another example, the surface of the filter media may contain monomers that polymerize after the filter media is formed as a result of the melt additive. In some such embodiments, in-line polymerization can be used. In-line polymerization (eg, in-line UV polymerization) is the process of curing a monomer or liquid polymer solution on a substrate under conditions sufficient to cause polymerization (eg, under UV irradiation).

In general, any suitable material may be used to alter the surface chemistry of the filter media, and thus alter the oleophobicity of the filter media. In some embodiments, the material can be charged. In some such embodiments, the surface charge of the filter media can further promote coalescence and/or increase oil carryover, as described in more detail herein. For example, in certain embodiments, filter media with a lipophilically modified surface can have reduced oil blow-by and/or produce larger coalesced droplets compared to filter media with an unmodified surface.

Typically, the net charge of the modified surface (e.g., modified such that the oil repellency level of the filter media (or one or more layers of the filter media) is greater than or equal to 1) can be negative, positive, or neutral . In some cases, the modified surface may contain negatively charged materials and/or positively charged materials. In some embodiments, the surface can be modified with an electrostatically neutral material. Non-limiting examples of materials that can be used to modify the surface include polyelectrolytes (e.g., anionic, cationic), oligomers, polymers (e.g., fluorinated polymers, perfluoroalkylethylmethyl Acrylates, polycaprolactone, poly[bis(trifluoroethoxy)phosphazene]), small molecules (e.g., carboxylate-containing monomers, amine-containing monomers, polyols), ionic liquids, Monomer precursors, and gases, and combinations thereof.

In embodiments comprising fluorinated polymers, the polymer may _comprise a species having the formula _{-CnF2n +1} or _-CnFm , where n is an integer greater than 1 and m is an integer greater than 1 (e.g. , -C ₆ F ₁₃ ). In some embodiments, the surface of the filter media can be modified with anionic polyelectrolytes. For example, one or more anionic polyelectrolytes can be sprayed or dipped onto at least one surface of the filter media. In some embodiments, the surface of the filter media can be modified with cationic polyelectrolytes. In some embodiments, the surface of the filter media can be modified with silicone (or derivatives thereof). For example, in certain embodiments, at least one surface of the filter media can be treated or coated with polydimethylsiloxane. In certain embodiments, the surface of the filter media can be silylated (eg, a substituted silyl group can be attached to at least one surface of the filter media).

In certain embodiments, filler materials (e.g., organic filler materials and inorganic filler materials) can be added to the filter media to modify the surface and/or oil repellency of the filter media (or one or more layers of the filter media) level. In some embodiments, small molecules (eg, monomers, polyols) as further defined below can be used to alter the level of oil repellency of the filter media. In certain embodiments, small molecules can be used as melt additives. In another example, small molecules can be deposited on at least one surface of the filter media by coating (eg, chemical vapor deposition). Regardless of the modification method, in some embodiments, small molecules on the surface of the filter media can polymerize after deposition.

In certain embodiments, at least one surface of the filter media can be modified with small molecules such as monocarboxylic acids and/or unsaturated dicarboxylic (di)acids. In certain embodiments, the small molecule can be an amine-containing small molecule. Amine-containing small molecules can be primary, secondary, or tertiary. In some of these cases, the small amine-containing molecule can be a monomer. In some embodiments, small molecules can be inorganic or organic hydrophobic molecules. Non-limiting examples include hydrocarbons (eg, CH ₄ , C ₂ H ₂ , C ₂ H ₄ , C ₆ H ₆ ), fluorocarbons (eg, CF ₄ , C ₂ F ₄ , C ₃ F ₆ , C ₃ F ₈ , C ₄ H ₈ , C ₅ H ₁₂ , C ₆ F ₆ , C ₆ F ₁₃ or other fluorocarbons of formula -C _n F _2n+1 or -C _n F _m , wherein n is an integer greater than 1 , and m is an integer greater than 1), silanes (eg, SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , Si ₄ H ₁₀ ), organosilanes (eg, methylsilane, dimethylsilane, triethylsilane ) and silicones (eg, dimethylsiloxane, hexamethyldisiloxane). In certain embodiments, a suitable hydrocarbon for modifying the surface of the filter media may have the formula _CxHy , where x is an integer from 1 to 10, and y is an integer _from 2 to 22. In certain embodiments, suitable silanes for modifying the surface of filter media may have the formula _{SinH2n +2} , where any hydrogen may be replaced with a halogen (e.g., Cl, F, Br, I) , where n is an integer from 1 to 10.

As used herein, "small molecule" refers to a molecule of relatively low molecular weight, whether occurring naturally or produced artificially (eg, by chemical synthesis). Typically, small molecules are organic compounds (ie, they contain carbon). Small organic molecules can contain multiple carbon-carbon bonds, stereocenters, and other functional groups (eg, amines, hydroxyls, carbonyls, heterocycles, etc.). In certain embodiments, the molecular weight of the small molecule is up to about 1,000 g/mol, up to about 900 g/mol, up to about 800 g/mol, up to about 700 g/mol, up to about 600 g/mol, up to about 500 g/mol, up to About 400 g/mol, up to about 300 g/mol, up to about 200 g/mol, or up to about 100 g/mol. In certain embodiments, the molecular weight of the small molecule is at least about 100 g/mol, at least about 200 g/mol, at least about 300 g/mol, at least about 400 g/mol, at least about 500 g/mol, at least about 600 g/mol, at least about 700 g/mol, at least about 800 g/mol, or at least about 900 g/mol, or at least about 1,000 g/mol. Combinations of the above ranges are also possible (eg, at least about 200 g/mol and up to about 500 g/mol).

In some embodiments, polymers can be used to alter the level of oil repellency of the filter media (or one or more layers of the filter media). For example, one or more polymers may be applied to at least a portion of the surface of the filter media by coating techniques. In certain embodiments, polymers may be formed from monocarboxylic acids and/or unsaturated dicarboxylic (di)acids. In certain embodiments, the polymer can be a graft copolymer and can be formed by grafting polymers or oligomers to fibers and/or polymers (eg, resinous polymers) in filter media. The graft polymer or oligomer may contain carboxyl moieties that may be used to form chemical bonds between the graft and the polymer in the fiber and/or filter media. Non-limiting examples of polymers that can be used to form graft copolymers in the fibers and/or filter media include polyethylene, polypropylene, polycarbonate, polyvinyl chloride, polytetrafluoroethylene, polystyrene, cellulose , polyethylene terephthalate, polybutylene terephthalate, and nylon, and combinations thereof. Graft polymerization can be initiated by chemical and/or radiochemical (eg electron beam, plasma, corona discharge, UV irradiation) methods. In some embodiments, the polymer may be a polymer having repeat units comprising amines (eg, polyallylamine, polyethyleneimine, polyoxazoline). In certain embodiments, the polymer may be a polyol.

In some embodiments, a gas may be used to alter the oil repellency level of the filter media (or one or more layers of the filter media). In some such cases, molecules in the gas may react with materials (e.g., fibers, resins, additives) on the surface of the filter media to form functional groups (e.g., charged moieties) and/or increase the oxygen content on the surface of the filter media . The weight percent of the material used to modify at least one surface of the filter media can be greater than or equal to about 0.0001 wt%, greater than or equal to about 0.0005 wt%, greater than or equal to about 0.001 wt%, greater than or equal to about 0.005 wt%, greater than or equal to about 0.01 wt%, greater than or equal to about 0.05 wt%, greater than or equal to about 0.1 wt%, greater than or equal to about 0.5 wt%, greater than or equal to about 1 wt%, greater than or equal to about 2 wt% %, or greater than or equal to about 3% by weight. In some cases, the weight percent of the material used to modify at least one surface of the filter media can be less than or equal to about 4 wt%, less than or equal to about 3 wt%, less than or equal to about 1 wt% of the filter media , less than or equal to about 0.5 wt%, less than or equal to about 0.1 wt%, less than or equal to about 0.05 wt%, less than or equal to about 0.01 wt%, or less than or equal to about 0.005 wt%. Combinations of the above-mentioned ranges are also possible (eg, weight percent of material greater than or equal to about 0.0001 weight percent and less than about 4 weight percent, or greater than or equal to about 0.01 weight percent and less than about 0.5 weight percent). Other ranges are also possible. The weight percent of material in the filter medium is based on the dry solids of the filter medium and can be determined by weighing the filter medium before and after application of the material.

A variety of materials can also be used to form the fibers of the outer layer or cover, including synthetic and non-synthetic materials. In an exemplary embodiment, the outer or cover layer is formed from staple fibers, particularly a combination of binder fibers and non-binder fibers. One suitable fiber composition is a blend of at least about 20% binder fibers and the balance non-binder fibers. Various types of binder and non-binder fibers can be used to form the media of the present invention, including those previously discussed above with respect to the open support layer and/or the coarse support layer.

The outer or cover layer can also be formed using a variety of techniques known in the art, including meltblowing, wet-laid techniques, air-laid techniques, carding, and spunbond. In an exemplary embodiment, the top layer is an airlaid layer and the bottom layer is a spunbond layer. The resulting layer can also have a variety of thicknesses, air permeability, and basis weights, depending on the requirements of the desired application.

As noted above, in some embodiments, layers of filter media (e.g., a first layer, a second layer, one or more coarse support layers) may be formed using a non-wet-laid process (e.g., an air-laid process). , carding process, melt blown process) formed non-wet-laid layer. For example, in a non-wet-laid process, an air-laid process or a carding process may be used. For example, in an airlaid process, the fibers can be mixed while air is blown onto a conveyor. In the carding process, in some embodiments, fibers are manipulated by a roller and extensions (eg, hooks, needles) associated with the roller.

In some embodiments, the layers of filter media may comprise fibers formed by a meltblowing process, as described herein. In embodiments where the filter media includes a meltblown layer, the meltblown layer may have one or more of the features described in: 2013 based on U.S. Patent Application Serial No. 12/266,892 filed May 14, 2009 Owned U.S. Patent No. 8,608,817, entitled "Meltblown Filter Medium," issued December 17; based on patent application Serial No. 12/971,539, filed December 17, 2010, entitled "Fine Fiber Filter Media and Processes" Owned U.S. Patent Publication No. 2012/0152824; commonly-owned U.S. Patent Publication No. 2012/0152824, entitled "Fine Fiber Milter Media and Processes," based on patent application Ser. No. 12/971,539 filed December 17, 2010; and commonly-owned U.S. Patent Publication No. 2012/0152821, entitled "FineFiber Milter Media and Processes," based on patent application Ser. No. 12/971,594, filed December 17, 2010, each of which is incorporated herein by reference in its entirety for all purposes .

For example, in one exemplary embodiment, a filter media includes a charged fiber layer comprising a plurality of fibers, wherein at least a portion of the plurality of fibers is formed by a meltblowing process.

Filter media can be used in many applications such as respirator and face mask applications, cabin air filtration, military apparel, HVAC systems (e.g. for industrial areas and buildings), clean rooms, vacuum filtration, furnace filtration, room air cleaning, high efficiency Particulate Acquisition (HEPA) Filters, Ultra Low Specific Air (ULPA) Filters, and Respirator Protection Equipment (eg, Industrial Respirators).

In some embodiments, filter media can be incorporated into the mask. The filter media can be folded, edge sealed, trimmed, or molded within the mask, for example, with or without a support structure. Face coverings can be full face or half face, and can be disposable or reusable. In general, face masks are used to protect the respiratory system when the air contains dangerous amounts of particulate pollutants in the form of solid particles or liquid droplets that may cause damage through inhalation. Therefore, face masks typically need to provide adequate protection with good breathability (eg, low drag). Face masks may be designed to filter dust, mist, smoke, vapor, smoke, spray or mist. For example, face masks may be worn in areas where activities such as grinding, welding, paving (eg, where hot asphalt fumes are present), coal mining, diverting diesel fuel, or pesticide spraying are performed. Face shields may also be designed to be worn in hospitals (for example, to perform surgery), stills and refineries in the chemical industry, painting facilities, or oil fields. For example, the mask may be a surgical mask or an industrial mask.

The filter media can be incorporated into a variety of other suitable filter elements for a variety of applications, including gas filtration. For example, filter media can be used in heating and air conditioning ducts. The filter element may have any suitable configuration known in the art, including bag filters and panel filters. Filter assemblies for filtration applications may include any of a variety of filter media and/or filter elements. A filter element may include the filter media and/or layers (eg, first layer, second layer) described above. Examples of filter elements include gas turbine filter elements, dust collector elements, heavy duty air filter elements, automotive air filter elements, air filter elements for large displacement gasoline engines (e.g., SUVs, pickup trucks, trucks), HVAC air filter elements , HEPA filter elements, ULPA filter elements, and vacuum bag filter elements.

The filter elements can be incorporated into corresponding filter systems (gas turbine filter systems, heavy duty air filter systems, automotive air filter systems, HVAC air filter systems, HEPA filter systems, ULPA filter systems, and vacuum bag filter systems). The filter media can optionally be pleated in any of a variety of configurations (eg, plates, columns).

The filter elements may also be of any suitable form, such as radial filter elements, plate filter elements or channel flow elements. Radial filter elements may comprise pleated filter media confined within two cylindrically shaped open wire support materials.

In some cases, the filter element includes a housing that can be positioned to surround the filter media. The housing can have various configurations, and configurations vary based on the intended application. In some embodiments, the housing may be formed from a frame positioned around the perimeter of the filter media. For example, the frame can be heat sealed around the perimeter. In some cases, the frame has a generally rectangular configuration surrounding all four sides of the generally rectangular filter media. The frame may be formed from a variety of materials including, for example, cardboard, metal, polymer, or any combination of suitable materials. The filter element may also include various other features known in the art, such as stabilization features to stabilize the filter media relative to the frame, spacers, or any other suitable features.

As noted above, in some embodiments, filter media may be incorporated into a bag (or pocket) filter element. A bag filter element may be formed by any suitable method, for example, by placing two filter media together (or folding a single filter media in half) and touching each other on three sides (or two sides if folded) , so that only one side remains open, thereby forming a pocket within the filter. In some embodiments, multiple filter pockets can be attached to the frame to form a filter element. It should be understood that filter media and filter elements can have a variety of different configurations, and that the particular configuration depends on the application in which the filter media and elements are used.

The filter element may have the same property values as those described above with respect to the filter media and/or layers. For example, the aforementioned instantaneous resistance, efficiency, (total) thickness and/or specific weight can also be found in filter elements. During use, as a fluid (eg, air) flows through the filter media, the filter media mechanically traps contaminant particles on the filter media.

In an exemplary embodiment, a filter media includes an open support layer, a charged fiber layer associated with the open support layer, and an additional layer associated with the charged fiber layer and the open support layer. In another exemplary embodiment, a filter media includes an open support layer, a charged fiber layer associated with the open support layer, an additional layer associated with the charged fiber layer and the open support layer, and a fine fiber layer associated with the additional layer. In yet another exemplary embodiment, a filter medium includes an open support layer, a charged fiber layer associated with the open support layer, an additional layer associated with the charged fiber layer and the open support layer, and maintaining at least the charged fiber layer in a corrugated configuration and A coarse support layer that maintains the separation of the peaks and troughs of adjacent waves of the charged fiber layer.

In some embodiments, the open support layer, charged fiber layer, additional layer, and/or fine fiber layer (if present) may be mechanically attached to each other (eg, needling).

In some embodiments, the air permeability of the open support layer is greater than 1100 CFM and less than or equal to 20000 CFM. In certain embodiments, the combined air permeability of the open support layer and the additional layer is greater than 45 CFM and less than 1100 CFM. In a particular set of embodiments, the open support layer comprises a mesh.

In some embodiments, the additional layer is a meltblown layer, a spunbond layer, or a carded layer. In a particular set of embodiments, the additional layer is a meltblown layer. In certain embodiments, the additional layer is a meltblown layer associated with the open support layer and may be laminated to the charged fiber layer. In some cases, the combined gamma value of the meltblown layer, open support layer, and charged fiber layer can be greater than or equal to 90 and less than or equal to 250. In some embodiments, the meltblown layer can be charged, for example, by hydrocharging.

In some embodiments, the filter media includes a fine fiber layer associated with additional layers. In certain embodiments, the fine fiber layer comprises a plurality of electrospun fibers. In some cases, the fine fiber layer can comprise a plurality of fibers having an average fiber diameter greater than or equal to 0.1 microns and less than or equal to 2 microns.

In some embodiments, the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer. In some embodiments, the total number of fibers in the charged fibrous layer (e.g., the total number of fibers in the first plurality of fibers and the second plurality of fibers) per gram of the charged fibrous layer is greater than or equal to 50,000 fibers per gram of the charged fibrous layer And less than or equal to 125,000 fibers. In certain embodiments, the BET surface area of the charged fibrous layer is greater than or equal to 0.33 m ² /g and less than or equal to 1.5 m ² /g. In some cases, the average length of the first plurality of fibers and/or the second plurality of fibers can be greater than or equal to 30 mm. In certain embodiments, the first plurality of fibers and/or the second plurality of fibers are multilobal (eg, trilobal).

In some embodiments, the filter media (and/or one or more layers of the filter media, such as charged fiber layers) can be antimicrobial. As used herein, the term "antimicrobial" is given its ordinary meaning in the art and generally refers to materials that destroy or inhibit the growth of microorganisms (e.g., bacteria, viruses, fungi) and in some cases pathogenic microorganisms ( For example, polymers).

In certain embodiments, the charged fiber layer and/or the open support layer of the filter media can be antimicrobial. In certain embodiments, one or more layers of filter media comprise a plurality of antimicrobial fibers. In an exemplary embodiment, the charged fibrous layer comprises a first plurality of fibers and a second plurality of fibers, wherein the first plurality of fibers (and/or the second plurality of fibers) comprises a plurality of antimicrobial fibers (e.g., comprising antimicrobial polymers). In another exemplary embodiment, the open support layer (eg, mesh, scrim, mesh, spunbond layer) comprises a plurality of antimicrobial fibers (eg, comprises an antimicrobial polymer).

In some cases, the plurality of (antimicrobial) fibers comprise a bacteriostatic, fungistatic, and/or virostatic polymer. In an exemplary embodiment, the plurality of (antimicrobial) fibers comprise a polymer such as polypropylene and are bacteriostatic, fungistatic and/or viral. Non-limiting examples of suitable polymers for antimicrobial fibers include polyethylene, polypropylene, polystyrene, ethylene/vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, polyamides (such as nylon), polyacrylonitrile , acrylic and polyethylene terephthalate. Based on the teachings of this specification, one of ordinary skill in the art will be able to select additional suitable polymers.

In certain embodiments, the plurality of fibers (e.g., the first plurality of fibers, the second plurality of fibers) of one or more layers of the filter media includes antimicrobial additives, such as bacteriostatic, fungistatic, and/or antimicrobial additives. Additives for viruses. Non-limiting examples of suitable antimicrobial additives include silver and its derivatives (e.g., silver particles, silver ions), zinc and its derivatives (e.g., zinc pyrithione), metal oxides (silver oxide, iron oxide oxides, titanium oxides, copper oxides, and zinc oxides), triclosan, quaternary ammonium compounds, chitosan, poly(hexamethylene biguanide), terpenes, flavonoids, quinones, lectins, and n- Haloamines. In an exemplary embodiment, the plurality of fibers comprises a polymer such as polypropylene and an antimicrobial additive such as triclosan. In another exemplary embodiment, the plurality of fibers comprises a polymer, such as polyamide or acrylic, and an antimicrobial additive, such as quaternary ammonium compounds, chitosan, and/or n-halamines. Other combinations of polymers and antimicrobial additives are also possible.

In some embodiments, the filter media (and/or one or more layers of filter media) can be engineered to have a specific bacterial filtration efficiency. In some embodiments, the bacterial filtration efficiency of the filter media (and/or one or more layers of the filter media) can be greater than or equal to 95%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5% , greater than or equal to 99.9%, greater than or equal to 99.99%, greater than or equal to 99.999%, greater than or equal to 99.999%, or greater than or equal to 99.9999%. In certain embodiments, the filter medium (and/or one or more layers of the filter medium) has a bacterial filtration efficiency of less than or equal to 99.99995%, less than or equal to 99.9999%, less than or equal to 99.999%, less than or equal to 99.99% , less than or equal to 99.9%, less than or equal to 99.5%, less than or equal to 99%, or less than or equal to 98%. Combinations of the above mentioned ranges are also possible (eg, greater than or equal to 95% and less than or equal to 99.99995%) Other ranges are also possible. Bacterial Filtration Efficiency as described herein is measured according to ASTM F2101 relative to a filter medium initially containing 1 million bacterial units provided at a face velocity of 12.5 cm/sec and a flow rate of 30 liters/min over an area of 40 ^cm2 upstream of the filter media. Bacteria (staphylococcus aureus) in aerosol, percentage of bacteria (staphylococcus aureus) collected downstream of the filter media.

In certain embodiments, the filter media (and/or one or more layers of filter media) can be engineered to have a particular virus filtration efficiency. In some embodiments, the virus filtration efficiency of the filter media (and/or one or more layers of the filter media) can be greater than or equal to 95%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5% , greater than or equal to 99.9%, greater than or equal to 99.99%, greater than or equal to 99.999%, greater than or equal to 99.999%, or greater than or equal to 99.9999%. In certain embodiments, the virus filtration efficiency of the filter medium (and/or one or more layers of the filter medium) is less than or equal to 99.99995%, less than or equal to 99.9999%, less than or equal to 99.999%, less than or equal to 99.99% , less than or equal to 99.9%, less than or equal to 99.5%, less than or equal to 99%, or less than or equal to 98%. Combinations of the above-mentioned ranges are also possible (eg, greater than or equal to 95% and less than or equal to 99.99995%). Other ranges are also possible. Virus filtration efficiency as described herein is measured according to ASTM F2101 relative to initially containing ¹⁰ plaque formation provided at a flow rate of 30 liters/min and a face velocity of 12.5 cm/sec upstream of the filter media over an area of 40 em ² Unit of virus in aerosol (Phi X174 phage), percentage of virus (Phi X174 phage) collected downstream of the filter medium.

In some embodiments, filter media can be designed to have desired fire resistance (e.g., F1 rating, K1 rating) and performance characteristics without, for example, compromising certain mechanical and/or filtration properties (e.g., printability of the media). folds). In certain embodiments, the filter media is flame resistant (eg, by a glow wire test according to IEC60695-2-11 (2010)). In certain embodiments, the charged fibrous layers of the filter media are configured to remain charged after direct contact with an ignition source (eg, a flame, a "glow" wire at 850°C). In certain embodiments, the first plurality of fibers and/or the second plurality of fibers are flame resistant.

In some embodiments, the filter media (and/or one or more layers of the filter media, such as charged fiber layers) can be flame resistant. In certain embodiments, the charged fibrous layer (or other layer) comprises a plurality of fibers (eg, a first plurality of fibers, a second plurality of fibers), wherein at least a portion of the plurality of fibers is flame resistant. For example, in some cases, the plurality of fibers may contain polymers and/or refractory additives. In some cases, the plurality of fibers does not include a refractory coating (eg, a coating that is different from the material from which the fibers are formed). Non-limiting examples of polymers for refractory fibers include polypropylene and polyester.

In some embodiments, the refractory fibers include refractory additives. In some cases, the fibers may also contain relatively low amounts or be substantially free (eg, contain no) of certain undesired components (eg, halogens, bromine, chlorine, antimony trioxide, metal hydrates). For example, the refractory additive fibers may include phosphorus-based refractory additives and/or nitrogen-based refractory additives. Non-limiting examples of refractory additives include phosphorus-based additives (e.g., propionylmethylphosphinate), dioxaphosphorinane and its derivatives, triazine-based compounds, phosphoramidates and their derivatives , allyl-functionalized polyphosphazenes, and non-halogenated compounds such as hydroxymethylphosphonium salts and N-methylolphosphonopropionamides and their derivatives.

In some embodiments, fibers comprising fire resistant additives can impart relatively high fire resistance to the filter media. For example, in some embodiments, the filter media may have an F1 rating and/or a K1 rating as measured according to DIN 53438 (June 1984). As used herein, the term "fire resistant filter media" (eg, including charged fiber layers) has its ordinary meaning in the art, and may refer to filter media that passes the glow wire test according to IEC60695-2-11 (2010). In certain embodiments, the filter media can be configured to pass a glow wire test at 850°C according to IEC60695-2-11 (2010). Briefly, the glow wire element was heated to 850° C. and brought into contact with the surface of the filter media with a force of 1 N for 30 seconds and then removed from the filter media. If the filter media does not burn within 30 seconds of removal of the glow wire (or, any flame self-extinguishes within 30 seconds of removal of the glow wire element), the filter media generally passes the glow wire test. In some embodiments, the charged fibrous layers of the filter media remain substantially charged after the glow wire test.

As used herein, the term "refractory fiber" has its ordinary meaning in the art and may refer to a fiber having a refractory additive distributed in and/or throughout the fiber. In general, the fibers may contain any suitable refractory additive having sufficient refractory properties.

In some embodiments, the refractory additive can be covalently attached to one or more components in the fiber. For example, the polymers in the fibers may contain fire resistant additives. In some such embodiments, the fire resistant additive can be in the backbone of the polymer and/or be a pendant group in the polymer. In some embodiments, a polymer comprising a fire resistant additive can be formed by reacting one or more functional groups on the polymer with a fire resistant additive. In certain embodiments, the polymer may be a copolymer comprising a fire resistant additive as a repeating unit. In some such cases, the polymer can be formed by reacting the monomers with the refractory additive as a comonomer. For example, a PET/fire additive copolymer can be added to a reaction mixture with terephthalic acid and ethylene glycol during an esterification reaction or to a reaction mixture with ethylene glycol and dimethyl terephthalate during a transesterification reaction. It is formed by adding phosphorus-based refractory additives. After the refractory additive is covalently attached to the components of the fiber, the components can be used to make fibers comprising the refractory additive.

Non-limiting examples of suitable monomers that can be copolymerized with the fire resistant additive include esters, olefins, styrene, vinyl chloride, vinyl monomers, amine monomers, monomers containing one or more carboxylic acids, bisphenols , phosgene, epoxy compounds, isocyanates, polyols, and combinations thereof. Non-limiting examples of polymers that can be modified with fire resistant additives include polypropylene, polyester, polyolefin, polystyrene, styrene copolymers, vinyl chloride polymers, vinyl polymers, polyamides, polycarbonates, Polyurethanes, polyepoxides, polyacrylonitriles, acrylics, PTFE, polyimides and polyimidazoles.

In some embodiments, the refractory additive may not be covalently attached to components of the fiber. In some embodiments, refractory additives may be added to the material used to form the fibers prior to fiber formation.

Other systems, devices, and applications are possible, and one skilled in the art will be able to select such systems, devices, and applications based on the teachings of this specification.

Example

Example 1

The following examples demonstrate the formation of filter media including open support layers and charged fiber layers according to some embodiments.

Sample 1 included several filter media of different basis weights, including:

Charged filter media having a basis weight of 20 g/m ² to 85 g/m ² comprising a plurality of charged fibers having an average fiber diameter greater than or equal to 15 microns; and

A support layer, comprising a scrim and having an air permeability of less than or equal to 1100 CFM, is needle punched to the charged filter media.

Sample 2 included several filter media of different basis weights, including:

Charged filter media having a basis weight of 20 g/m ² to 85 g/m ² comprising a plurality of charged fibers having an average fiber diameter of less than 15 microns; and

The open support layer (mesh), with an air permeability greater than 1100 CFM, is needled to the charged filter media.

The web of Sample 2 comprised polypropylene threads with a thread count of 5 threads/inch along the first axis and 6 threads/inch along the second axis.

Figure 3 shows a plot of normalized γ versus the constant weight of the charged fiber layer. Figure 4 shows a plot of normalized efficiency versus the constant weight of the charged fiber layer. Compared to Sample 1, the filter media of Sample 2 demonstrates an increase in normalized gamma and normalized efficiency even at relatively low basis weights of the charged fiber layer.

Figure 5 is a graph of pressure drop (Pa) versus constant weight of a charged fiber layer. The filter media of Sample 2 demonstrated reduced resistance compared to Sample 1 .

Figure 6 is a graph of the dust holding capacity of sample 1 at a basis weight of 70 g/m ² relative to sample 2 at a basis weight of 70 g/m ² . The filter media of Sample 2 demonstrates a significant increase in the dust holding capacity of the filter media for a given air resistance compared to Sample 1 .

Although various embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily conceive of methods for performing the functions described herein and/or obtaining the results described herein and/or one or more Various other means and/or structures to achieve the above advantages, and each such changes and/or modifications are considered to be within the scope of the present invention. More generally, those skilled in the art will readily recognize that all parameters, dimensions, materials and configurations described herein are intended to be exemplary and that actual parameters, dimensions, materials and/or configurations will depend upon the use of the present invention. One or more specific applications of the teachings of . Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is therefore to be understood that the foregoing embodiments are presented by way of example only, and that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, kit and/or method described herein. Furthermore, any combination of two or more such features, systems, articles, materials, kits and/or methods is included in this disclosure if two or more such features, systems, articles, materials, kits and/or methods are not mutually inconsistent. within the scope of the invention.

Unless clearly stated to the contrary, as used herein in the specification and claims, a subject without a quantifier modifier shall be understood to mean "at least one".

As used herein in the specification and claims, the phrase "and/or" should be understood to mean "either or both" of elements that are conjoined, co-existing in some instances and separately in other instances. elements of existence. Other elements may optionally be present other than the elements specifically identified by the "and/or" clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, reference to "A and/or B" when used in conjunction with open-ended language such as "comprises" may in some embodiments refer to A without the presence of B (optionally including other than B). elements other than A); in another embodiment, B in the absence of A (optionally including elements other than A); in yet another embodiment both A and B (optionally including other elements); etc. .

"Or" as used herein in the specification and claims should be understood to have the same meaning as "and/or" defined above. For example, "or" or "and/or" when separating items in a list should be understood to include, i.e. include a plurality of elements or at least one of the list of elements, but also include more than one of them, and optionally Includes additional items not listed. Terms to the contrary, such as "only one" or "exactly one", or "consisting of" when used in a claim, mean inclusion of a plurality of elements or exactly one element of a list of elements only if the contrary is expressly stated. Generally, the term "or" as used herein when preceded by an exclusive term such as "either", "one", "only one" or "exactly one" should only be understood to mean an exclusive alternative (ie "one or the other, but not both"). "Consisting essentially of" when used in a claim shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and claims, the phrase "at least one" when referring to a list of one or more elements should be understood to mean at least one element selected from any one or more elements in the list of elements. An element, but does not necessarily include at least one of each element specifically listed in the list of elements, nor does it exclude any combination of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified in the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B", or equivalently, "at least one of A and/or B") in some An embodiment may refer to at least one A, optionally including more than one A, but the absence of B (and optionally includes elements other than B); in another embodiment, may refer to at least one B, any optionally including more than one B, but not A (and optionally including elements other than A); in yet another embodiment, may refer to at least one A, optionally including more than one A, and at least a B, optionally including more than one B (and optionally including other elements); etc.

In the claims as well as in the above specification, all transitional phrases such as "comprises", "comprises", "with", "has", "contains", "relates to", "has", etc. are to be read as Open-ended means including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as described in Section 2111.03 of the USPTO Manual of Patent Examining Procedures.

The following technical solutions are also provided in the present invention:

Note 1. A filter medium comprising:

open support layer; and

a charged fiber layer mechanically attached to said open support layer,

wherein the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer,

wherein the first polymer is acrylic, and

Wherein the open support layer is a mesh with an air permeability greater than 1100 CFM and less than or equal to 20000 CFM.

Note 2. A filter medium comprising:

open support layer; and

a charged fiber layer mechanically attached to said open support layer,

wherein the charged fibrous layer comprises a plurality of fibers having an average fiber diameter less than 15 microns and greater than or equal to 1 micron, and

Wherein the open support layer is a mesh with an air permeability greater than 1100 CFM and less than or equal to 20000 CFM.

Note 3. A filter medium comprising:

open support layer; and

a charged fiber layer mechanically attached to the support layer,

wherein the air permeability of the open support layer is greater than 1100CFM and less than or equal to 20000CFM,

wherein the total weight of the filter medium is greater than or equal to 12g/m ² and less than or equal to 700g/m ² ,

wherein the gamma of the filter medium is greater than or equal to 90 and less than or equal to 250, and

Wherein the total air permeability of the filter medium is greater than or equal to 30 CFM and less than or equal to 1100 CFM.

Note 4. The filter media of note 2 or 3, wherein the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer.

Note 5. The filter medium of any preceding note, wherein the first polymer and the second polymer have different dielectric constants.

Note 6. The filter media of any preceding note, wherein the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 0.8 and less than or equal to 8.

Note 7. The filter media of any preceding note, wherein the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 1.5 and less than or equal to 5.

Note 8. The filter medium of any preceding note, wherein the second polymer comprises a synthetic material selected from the group consisting of polypropylene, dry spun acrylic, polyvinyl chloride, modified acrylic, wet spun acrylic , polytetrafluoroethylene, polypropylene, polystyrene, polysulfone, polyethersulfone, polycarbonate, nylon, polyurethane, phenolic resin, polyvinylidene fluoride, polyester, polyaramid, polyimide, poly Olefins, Kevlar, Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, and combinations thereof.

Note 9. The filter media of any preceding note, wherein the second polymer is polypropylene.

Note 10. The filter medium of any preceding note, wherein the second polymer is present in an amount greater than or equal to 10 wt. % and less than or equal to 90 wt. In the charged fiber layer.

Note 11. The filter medium of any preceding note, wherein the second polymer is present in an amount greater than or equal to 25 wt. % and less than or equal to 75 wt. In the charged fiber layer.

Note 12. The filter media of any preceding note, wherein the second polymer is present in an amount greater than or equal to 35 wt. % and less than or equal to 65 wt. In the charged fiber layer.

Note 13. The filter medium of any preceding note, wherein the first polymer comprises a synthetic material selected from the group consisting of: polypropylene, dry spun acrylic, polyvinyl chloride, modified acrylic, wet spun acrylic , polytetrafluoroethylene, polypropylene, polystyrene, polysulfone, polyethersulfone, polycarbonate, nylon, polyurethane, phenolic resin, polyvinylidene fluoride, polyester, polyaramid, polyimide, poly Olefins, Kevlar, Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, and combinations thereof.

Note 14. The filter medium of any preceding note, wherein the first polymer is a dry spun acrylic.

Note 15. The filter medium of any preceding note, wherein the first polymer is present in an amount greater than or equal to 10 wt. % and less than or equal to 90 wt. In the charged fiber layer.

Note 16. The filter media of any preceding note, wherein the first polymer is present in an amount greater than or equal to 25 wt. % and less than or equal to 75 wt. In the charged fiber layer.

Note 17. The filter media of any preceding note, wherein the first polymer is present in an amount greater than or equal to 35 wt. % and less than or equal to 65 wt. In the charged fiber layer.

Note 18. The filter media of any preceding note, wherein the first plurality of fibers has an average fiber diameter less than 15 microns and greater than or equal to 1 micron.

Note 19. The filter media of any preceding note, wherein the second plurality of fibers has an average fiber diameter less than 15 microns and greater than or equal to 1 micron.

Note 20. The filter media of any preceding note, wherein the open support layer has a solidity of less than or equal to 10% and greater than or equal to 0.1%.

Note 21. The filter media of any preceding note, wherein the open support layer has a solidity of less than or equal to 2% and greater than or equal to 0.1%.

Note 22. The filter medium of any preceding note, wherein the charged fibrous layer is needled to the support layer.

Note 23. The filter medium of any preceding note, wherein the charged fibrous layer is needled to the support layer at a perforation density of greater than or equal to 15 perforations/cm2 and less than or equal to 60 perforations/cm2 .

Note 24. The filter medium of any preceding note, wherein the charged fibrous layer is needled to the support layer with a needle penetration depth of greater than or equal to 8 mm and less than or equal to 20 mm.

Note 25. The filter medium of any preceding note, wherein the charged fibrous layer has a basis weight of greater than or equal to 10 g/m ² and less than or equal to 600 g/m ² .

Note 26. The filter medium of any preceding note, wherein the open support layer has a basis weight of less than or equal to 200 g/m ² and greater than or equal to 2 g/m ² .

Note 27. The filter medium of any preceding note, wherein the open support layer has a basis weight of less than or equal to 50 g/ ^m2 and greater than or equal to 5 g/ ^m2 .

Note 28. The filter media of any preceding note, wherein the open support layer has a thread count along the first axis greater than or equal to 2 threads/inch and less than or equal to 27 threads/inch.

Note 29. The filter media of any preceding note, wherein the open support layer has a thread count along the first axis greater than or equal to 3 threads/inch and less than or equal to 20 threads/inch.

Note 30. The filter media of any preceding note, wherein the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 2 mm.

Note 31. The filter media of any preceding note, wherein the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 10 microns.

Note 32. The filter media of any preceding note, wherein the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns.

Note 33. The filter media of any preceding note, wherein the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 500 microns and less than or equal to 2 mm.

Note 34. The filter media of any preceding note, wherein the charged fibrous layer has an air permeability greater than or equal to 10 CFM and less than or equal to 1200 CFM.

Note 35. The filter media of any preceding note, wherein the open support layer is formed by a spunbond process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns.

Note 36. The filter media of any preceding note, wherein the open support layer is formed by a meltblown process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 10 microns.

Note 37. The filter medium of any preceding note, wherein the open support layer is a mesh and comprises a plurality of wires having an average wire diameter greater than or equal to 500 microns and less than or equal to 2 mm.

Note 38. The filter media of any preceding note, wherein the charged fibrous layer has an uncompressed thickness of greater than or equal to 5 mils and less than or equal to 600 mils, or greater than or equal to 30 mils and less than or equal to 350 mils mil.

Note 39. The filter media of any preceding note, wherein the charged fibrous layer has an air permeability greater than or equal to 10 CFM and less than or equal to 1200 CFM.

Note 40. The filter media of any preceding note, wherein the charged fibrous layer has an air permeability greater than or equal to 80 CFM and less than or equal to 1200 CFM.

Note 41. The filter media of any preceding note, wherein the charged fibrous layer has an air permeability greater than or equal to 50 CFM and less than or equal to 650 CFM.

Note 42. The filter medium of any preceding note, wherein the filter medium has a total basis weight greater than or equal to 12 g/ ^m2 and less than or equal to 700 g/ ^m2 .

Note 43. The filter medium of any preceding note, wherein the filter medium has a total basis weight greater than or equal to 25 g/ ^m2 and less than or equal to 650 g/ ^m2 .

Note 44. The filter media of any preceding note, wherein the filter media has a total thickness of greater than or equal to 5 mils and less than or equal to 600 mils.

Note 45. The filter media of any preceding note, wherein the filter media has a total thickness of greater than or equal to 30 mils and less than or equal to 350 mils.

Note 46. The filter medium of any preceding note, wherein the filter medium has a total air permeability of greater than or equal to 30 CFM and less than or equal to 1100 CFM.

Note 47. The filter medium of any preceding note, wherein the filter medium has a normalized efficiency greater than or equal to 1 and less than or equal to 3.5.

Note 48. The filter medium of any preceding note, wherein the filter medium has a dust holding capacity of greater than or equal to about 1 g/ ^m2 and less than or equal to about 140 g/ ^m2 .

Note 49. The filter medium of any preceding note, wherein the filter medium has a dust holding capacity of greater than or equal to about 80 g/ ^m2 and less than or equal to about 140 g/ ^m2 .

Note 50. The filter medium of any preceding note, wherein the filter medium has a gamma of 30 or more and 250 or less.

Note 51. The filter medium of any preceding note, wherein the filter medium has a gamma of 75 or more and 150 or less.

Note 52. The filter medium of any preceding note, wherein the filter medium has a normalized gamma greater than or equal to 1 and less than or equal to 10.9.

Note 53. The filter medium of any preceding note, wherein the filter medium has a normalized γ greater than or equal to 1 and less than or equal to 5.6.

Note 54. The filter medium of any preceding note, wherein the filter medium has an initial efficiency of greater than or equal to 50% and less than or equal to 99.999%.

Note 55. The filter medium of any preceding note, wherein the filter medium has an initial efficiency of greater than or equal to 90% and less than or equal to 99.999%.

Note 56. A filter medium comprising:

Charged fiber layer;

an open support layer mechanically attached to said charged fiber layer; and

a coarse support layer that maintains said charged fiber layer in a wave-like configuration and maintains separation of peaks and troughs of adjacent waves of said charged fiber layer,

wherein the charged fiber layer has a basis weight less than or equal to 12 g/m ² and greater than or equal to 250 g/m ² ,

wherein the air permeability of the open support layer is greater than 1100 CFM and less than or equal to 20000 CFM, and

Wherein the total air permeability of the filter medium is greater than or equal to 10 CFM and less than or equal to 1000 CFM.

Additional Note 57. The filter media of additional note 56, wherein the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer.

Additional Note 58. The filter medium of any one of Additional Notes 56 to 57, wherein the first polymer and the second polymer have different dielectric constants.

Additional Note 59. The filter medium of any one of Additional Notes 56 to 58, wherein the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 0.8 and less than or equal to 8, or Greater than or equal to 1.5 and less than or equal to 5.

Additional Note 60. The filter medium of any one of Additional Notes 56 to 59, wherein the second polymer comprises a synthetic material selected from the group consisting of polypropylene, dry spun acrylic, polyvinyl chloride, modified acrylic, wet spun Acrylic, PTFE, Polypropylene, Polystyrene, Polysulfone, Polyethersulfone, Polycarbonate, Nylon, Polyurethane, Phenolic, Polyvinylidene Fluoride, Polyester, Polyaramide, Polyimide , polyolefins, Kevlar, Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, and combinations thereof.

Additional Note 61. The filter medium of any one of Additional Notes 56 to 60, wherein the second polymer is polypropylene.

Additional note 62. The filter medium according to any one of additional notes 56 to 61, wherein the second polymer is present in an amount of greater than or equal to 10% by weight and less than or equal to 90% by weight relative to the total weight of the charged fibrous layer The amount exists in the charged fiber layer.

Additional Note 63. The filter medium according to any one of Additional Notes 56 to 62, wherein the second polymer is present in an amount of greater than or equal to 25% by weight and less than or equal to 75% by weight relative to the total weight of the charged fibrous layer The amount exists in the charged fiber layer.

Additional Note 64. The filter medium according to any one of Additional Notes 56 to 63, wherein the second polymer is present in an amount of greater than or equal to 35% by weight and less than or equal to 65% by weight relative to the total weight of the charged fibrous layer The amount exists in the charged fiber layer.

Additional Note 65. The filter medium of any one of Additional Notes 56 to 64, wherein the first polymer comprises a synthetic material selected from the group consisting of polypropylene, dry spun acrylic, polyvinyl chloride, modified acrylic, wet spun Acrylic, PTFE, Polypropylene, Polystyrene, Polysulfone, Polyethersulfone, Polycarbonate, Nylon, Polyurethane, Phenolic, Polyvinylidene Fluoride, Polyester, Polyaramide, Polyimide , polyolefins, Kevlar, Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, and combinations thereof.

Additional Note 66. The filter medium of any one of Additional Notes 56 to 65, wherein the first polymer is a dry spun acrylic.

Additional Note 67. The filter medium according to any one of Additional Notes 56 to 66, wherein the first polymer is present in an amount of greater than or equal to 10% by weight and less than or equal to 90% by weight relative to the total weight of the charged fibrous layer The amount exists in the charged fiber layer.

Additional Note 68. The filter medium of any one of Additional Notes 56 to 67, wherein the first polymer is present in an amount of greater than or equal to 25% by weight and less than or equal to 75% by weight relative to the total weight of the charged fibrous layer The amount exists in the charged fiber layer.

Additional Note 69. The filter medium according to any one of Additional Notes 56 to 68, wherein the first polymer is present in an amount of greater than or equal to 35% by weight and less than or equal to 65% by weight relative to the total weight of the charged fibrous layer The amount exists in the charged fiber layer.

Additional Note 70. The filter media of any one of Additional Notes 56 to 69, wherein the first plurality of fibers has an average fiber diameter less than 15 microns and greater than or equal to 1 micron.

Additional Note 71. The filter media of any one of Additional Notes 56 to 70, wherein the second plurality of fibers has an average fiber diameter less than 15 microns and greater than or equal to 1 micron.

Additional Note 72. The filter media of any one of Additional Notes 56 to 71, wherein the charged fibrous layer has a period greater than or equal to 10 waves/6 inches and less than or equal to 40 waves/6 inches.

Supplement 73. The filter media of any one of Supplements 56 to 72, wherein the charged fibrous layer has a period greater than or equal to 5 waves/6 inches and less than or equal to 9 waves/6 inches.

Supplement 74. The filter media of any one of Supplements 56 to 73, wherein the charged fibrous layer has a period greater than or equal to 3 waves/6 inches and less than or equal to 15 waves/6 inches.

Additional Note 75. The filter medium of any one of Additional Notes 56 to 74, wherein the open support layer has a solidity of less than or equal to 10% and greater than or equal to 0.1%.

Additional Note 76. The filter medium of any one of Additional Notes 56 to 75, wherein the open support layer has a solidity of less than or equal to 2% and greater than or equal to 0.1%.

Additional Note 77. The filter medium of any one of Additional Notes 56 to 76, wherein the charged fibrous layer is needle punched to the support layer.

Additional Note 78. The filter medium of any one of Additional Notes 56 to 77, wherein the charged fibrous layer is needle punched to the support layer.

Additional Note 79. The filter medium of any one of Additional Notes 56 to 78, wherein the charged fibrous layer is needled to the support layer at a needle penetration depth of greater than or equal to 8 mm and less than or equal to 20 mm.

Note 80. The filter medium of any one of Notes 56 to 79, wherein the charged fibrous layer has a basis weight of greater than or equal to 10 g/m ² and less than or equal to 600 g/m ² .

Note 81. The filter medium of any one of Notes 56 to 80, wherein the open support layer has a basis weight of less than or equal to 200 g/m ² and greater than or equal to 2 g/m ² .

Note 82. The filter medium of any one of Notes 56 to 81, wherein the open support layer has a basis weight of less than or equal to 50 g/m ² and greater than or equal to 5 g/m ² .

Supplement 83. The filter media of any one of Supplements 56 to 82, wherein the open support layer has a count of threads along the first axis greater than or equal to 3 threads/inch and less than or equal to 20 threads/inch.

Supplement 84. The filter media of any one of Supplements 56 to 83, wherein the open support layer has a thread count along the first axis greater than or equal to 2 threads/inch and less than or equal to 27 threads/inch.

Additional Note 85. The filter medium of any one of Additional Notes 56 to 84, wherein the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 2 mm.

Additional Note 86. The filter media of any one of Additional Notes 56 to 85, wherein the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 10 microns.

Additional Note 87. The filter media of any one of Additional Notes 56 to 86, wherein the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns.

Additional Note 88. The filter media of any one of Additional Notes 56 to 87, wherein the open support layer comprises a plurality of fibers or threads having an average fiber diameter greater than or equal to 500 microns and less than or equal to 2 mm.

Supplement 89. The filter medium of any one of Supplements 56 to 88, wherein the charged fibrous layer has an air permeability greater than or equal to 10 CFM and less than or equal to 1200 CFM.

Additional Note 90. The filter media of any one of Additional Notes 56 to 89, wherein the open support layer is formed by a spunbond process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns.

Additional Note 91. The filter media of any one of Additional Notes 56 to 90, wherein the open support layer is formed by a meltblown process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 0.5 microns and a mesh less than or equal to 10 microns.

Addendum 92. The filter medium of any one of addenda 56 to 91, wherein the open support layer is a mesh and comprises a plurality of wires having an average wire diameter greater than or equal to 500 microns and less than or equal to 2 mm.

Additional Note 93. The filter media of any one of Additional Notes 56 to 92, wherein the charged fibrous layer has an air permeability greater than or equal to 10 CFM and less than or equal to 1200 CFM.

Supplement 94. The filter media of any one of Supplements 56 to 93, wherein the charged fibrous layer has an air permeability of greater than or equal to 80 CFM and less than or equal to 1200 CFM.

Additional Note 95. The filter media of any one of Additional Notes 56 to 94, wherein the charged fibrous layer has an air permeability greater than or equal to 50 CFM and less than or equal to 650 CFM.

Supplement 96. The filter medium of any one of Supplements 56 to 95, wherein the filter medium has a total basis weight greater than or equal to 30 g/m ² and less than or equal to 800 g/m ² .

Supplement 97. The filter medium of any one of Supplements 56 to 96, wherein the filter medium has a total basis weight greater than or equal to 100 g/m ² and less than or equal to 450 g/m ² .

Side Note 98. The filter media of any one of Notes 56 to 97, wherein the filter media has a total thickness of greater than or equal to 100 mils and less than or equal to 4000 mils.

Side Note 99. The filter media of any one of Notes 56 to 98, wherein the filter media has a total thickness greater than 150 mils and less than or equal to 1000 mils.

Addendum 100. The filter medium of any one of addendums 56 to 99, wherein the filter medium has a total air permeability of greater than or equal to 100 CFM and less than or equal to 700 CFM.

Additional Note 101. The filter medium of any one of Additional Notes 56 to 100, wherein the filter medium has a total air permeability of greater than or equal to 10 CFM and less than or equal to 1000 CFM.

Supplement 102. The filter medium according to any one of Supplements 56 to 101, wherein the filter medium has a dust holding capacity of greater than or equal to 5 g/m ² and less than or equal to 600 g/m ² .

Supplement 103. The filter medium according to any one of Supplements 56 to 102, wherein the filter medium has a dust holding capacity of greater than or equal to 200 g/m ² and less than or equal to 350 g/m ² .

Supplement 104. The filter medium of any one of Supplements 56 to 103, wherein the filter medium has a gamma of 75 or more and 150 or less.

Supplement 105. The filter medium of any one of Supplements 56 to 104, wherein the filter medium has a gamma of 20 or more and 250 or less.

Additional Note 106. The filter medium of any one of Additional Notes 56 to 105, wherein the initial efficiency of the filter medium is greater than or equal to 50% and less than or equal to 99.999%.

Additional Note 107. The filter medium of any one of Additional Notes 56 to 106, wherein the initial efficiency of the filter medium is greater than or equal to 90% and less than or equal to 99.999%.

Addendum 108. The filter medium of any preceding addendum, wherein the filter medium comprises a coarse support layer.

Addendum 109. The filter medium of addendum 108, wherein the coarse support layer comprises a plurality of fibers having an average fiber diameter greater than or equal to 8 microns and less than or equal to 85 microns.

Addendum 110. The filter medium of addendum 108 or 109, wherein the coarse support layer comprises a plurality of fibers having an average fiber diameter greater than or equal to 12 microns and less than or equal to 60 microns.

Addendum 111. The filter medium of any one of addendums 108 to 110, wherein the coarse support layer has a basis weight less than or equal to 100 g/ ^m2 and greater than or equal to 5 g/ ^m2 .

Addendum 112. The filter medium of any one of addendums 108 to 111, wherein the coarse support layer has a basis weight of less than or equal to 40 g/ ^m2 and greater than or equal to 12 g/ ^m2 .

Note 113. The filter medium of any preceding note, wherein the filter medium comprises an outer layer.

Note 114. A filter medium comprising:

An open support layer with an air permeability greater than 1100CFM and less than or equal to 20000CFM;

a charged fibrous layer adjacent to the open support layer and comprising a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer;

an additional layer associated with said open support layer and said charged fiber layer; and

a thin fiber layer associated with said additional layer,

wherein the fine fiber layer comprises a plurality of electrospun fibers;

Wherein the combined air permeability of the open support layer and the additional layer is greater than 45 CFM and less than 1100 CFM.

Additional Note 115. The filter medium of Additional Note 114, wherein the additional layer is a meltblown layer, a spunbond layer, or a carded layer.

Note 116. A filter medium comprising:

An open support layer with an air permeability greater than 1100CFM and less than or equal to 20000CFM;

a charged fibrous layer adjacent to the open support layer and comprising a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer;

an additional layer associated with the open support layer and the charged fibrous layer, wherein the additional layer comprises a plurality of meltblown fibers; and

a coarse support layer that maintains at least said charged fiber layer in a wave-shaped configuration and maintains separation of peaks and valleys of adjacent waves of said charged fiber layer,

Wherein the combined air permeability of the open support layer and the additional layer is greater than 45 CFM and less than 1100 CFM.

Note 117. A filter medium comprising:

open support layer;

a charged fibrous layer mechanically attached to the open support layer, wherein the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer;

an additional layer associated with said open support layer and said charged fiber layer; and

a coarse support layer that maintains at least said charged fiber layer in a wave-shaped configuration and maintains separation of peaks and valleys of adjacent waves of said charged fiber layer,

Wherein the combined air permeability of the open support layer and the additional layer is greater than or equal to 45 CFM and less than 1100 CFM.

Note 118. The filter media of any preceding note, wherein the combined air permeability of the open support layer and the additional layer is greater than or equal to 45 CFM and less than or equal to 700 CFM.

Note 119. The filter medium of any preceding Note, further comprising a layer of fine fibers.

Addendum 120. The filter medium of addendum 119, wherein the fine fiber layer is formed by an electrospinning process.

Note 121. The filter media of any preceding note, wherein the fine fiber layer comprises a plurality of fibers having an average cross-sectional dimension greater than or equal to 0.08 micron and less than or equal to 1 micron.

Note 122. The filter media of any preceding note, wherein the fine fiber layer has a basis weight of greater than or equal to 0.01 gsm and less than or equal to 10 gsm.

Note 123. The filter media of any preceding note, wherein the total air permeability of the fine fiber layer, the open support layer, and the additional layer is greater than or equal to 10 CFM and less than or equal to 500 CFM.

Note 124. The filter medium of any preceding Note, wherein the plurality of fibers of the fine fiber layer comprise a polymer selected from the group consisting of nylon, polypropylene, polylactic acid, polyacrylic acid, polyacrylonitrile, polycarbonate , polyethersulfone, polyester, polyvinyl alcohol, polyvinyl chloride and polyvinylidene fluoride.

Addendum 125. The filter medium of addendum 114 or 116, wherein the additional layer is a meltblown layer, a spunbond layer, or a carded fiber layer.

Note 126. The filter media of any preceding note, wherein the additional layer has a basis weight of greater than or equal to 3 gsm and less than or equal to 100 gsm.

Note 127. The filter media of any preceding note, wherein the additional layer and the open support layer have a combined basis weight greater than or equal to 10 gsm and less than or equal to 140 gsm.

Note 128. The filter media of any preceding note, wherein the additional layer has an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 20 microns.

Note 129. The filter media of any preceding note, wherein the additional layer has an air permeability greater than or equal to 45 CFM and less than 1100 CFM.

Note 130. The filter medium of any preceding note, wherein the additional layer is charged.

Note 131. The filter medium of any preceding note, wherein the additional layer is uncharged.

Note 132. The filter media of note 1 or 3, wherein the charged fiber layer is mechanically attached to the open support layer and/or the additional layer.

Note 133. The filter medium of any preceding note, wherein the filter medium has an oil repellency level of 1 or greater.

Addendum 134. The filter medium of addendum 64, wherein at least one surface of a layer of the filter medium is modified such that the filter medium has an oil repellency level of 1 or greater.

Note 135. The filter medium of any preceding note, wherein the filter medium comprises an outer layer.

Note 136. The filter media of any preceding note, wherein the coarse support layer maintains the open support layer, the charged fiber layer, and the additional layers associated with the open support layer in a corrugated configuration.

Note 137. A filter medium comprising:

a charged fibrous layer comprising a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer,

Wherein the BET surface area of the charged fiber layer is greater than or equal to 0.35 m ² /g and less than or equal to 125,000 fibers per gram of the charged fiber layer.

Additional note 138. The filter medium according to additional note 1, wherein the cross-sectional shape of the first plurality of fibers and/or the second plurality of fibers is selected from the group consisting of circular, oval, dog-bone, kidney bean, and ribbon , irregular and multilobal.

Note 139. The filter media of any preceding note, wherein the first plurality of fibers and/or the second plurality of fibers have an average largest cross-sectional dimension greater than or equal to 2 microns and less than or equal to 15 microns.

Note 140. The filter media of any preceding note, comprising an open support layer having an air permeability greater than or equal to 500 CFM adjacent the charged fibrous layer.

Note 141. The filter media of any preceding note, wherein the charged fiber layer is in a corrugated configuration.

Note 142. The filter medium of any preceding note, wherein the filter medium is antimicrobial.

Note 143. The filter medium of any preceding note, wherein the charged fibrous layer is antimicrobial.

Note 144. The filter medium of any preceding note, wherein the open support layer is antimicrobial.

Note 145. The filter media of any preceding note, wherein the first plurality of fibers and/or the second plurality of fibers are antimicrobial.

Note 146. The filter medium of any preceding note, wherein the filter medium has a bacterial filtration efficiency of greater than or equal to 99.999%.

Note 147. The filter medium of any preceding note, wherein the filter medium has a virus filtration efficiency of greater than or equal to 99.999%.

Note 148. The filter medium of any preceding note, wherein the first plurality of fibers comprises a bacteriostatic, fungistatic and/or virustatic additive.

Note 149. The filter medium of any preceding note, wherein the first plurality of fibers comprises bacteriostatic, fungistatic, and/or virally inhibited polypropylene.

Note 150. The filter media of any preceding note, wherein the second plurality of fibers comprises acrylic.

Note 151. The filter media of any preceding note, wherein the open support layer is mechanically attached to the charged fibrous layer.

Note 152. The filter media of any preceding note, wherein the charged fibrous layer has a BET surface area greater than or equal to 0.35 ^m2 /g and less than or equal to 1 ^m2 /g.

Note 153. The filter media of any preceding note, wherein the charged fibrous layer has less than or equal to 125,000 fibers per gram of the charged fibrous layer and greater than or equal to 50,000 fibers per gram of the charged fibrous layer.

Note 154. The filter media of any preceding note, wherein the charged fibrous layer has less than or equal to 105,000 fibers per gram of the charged fibrous layer and greater than or equal to 75,000 fibers per gram of the charged fibrous layer.

Note 155. The filter medium of any preceding note, wherein the filter medium is fire resistant and passes the glow wire test according to IEC60695-2-11.

Note 156. The filter media of any preceding note, wherein the charged fibrous layer is configured to remain charged after direct contact with an ignition source.

Note 157. The filter media of any preceding note, wherein the second plurality of fibers is flame resistant.

Note 158. The filter media of any preceding note, wherein the second plurality of fibers comprises polyester.

Note 159. The filter media of any preceding note, wherein the first plurality of fibers comprises polypropylene.

Note 160. The filter media of any preceding note, wherein the first plurality of fibers is present in the charged fibrous layer in an amount greater than or equal to 60 wt %, relative to the weight of the charged fibrous layer.

Note 161. The filter media of any preceding note, wherein the first plurality of fibers and/or the second plurality of fibers do not comprise a refractory coating.

Note 162. The filter media of any preceding note, wherein the open support layer has an air permeability greater than 500 CFM and less than or equal to 20,000 CFM.

Note 163. The filter media of any preceding note, wherein the open support layer has an air permeability greater than 1100 CFM and less than or equal to 20000 CFM.

Note 164. The filter media of any preceding note, wherein the open support layer has an air permeability greater than 500 CFM and less than or equal to 1400 CFM.

Note 165. The filter medium of any preceding note, wherein the open support layer is a mesh.

Note 166. The filter media of any preceding note, wherein the open support layer is a spunbond layer.

Note 167. The filter media of any preceding note, wherein the open support layer has a solidity of less than or equal to 10% and greater than or equal to 0.1%.

Note 168. The filter media of any preceding note, wherein the open support layer has a solidity of less than or equal to 2% and greater than or equal to 0.1%.

Note 169. The filter media of any preceding note, wherein the open support layer has a basis weight of less than or equal to 200 g/ ^m2 and greater than or equal to 2 g/ ^m2 .

Note 170. The filter media of any preceding note, wherein the open support layer has a basis weight of less than or equal to 40 g/ ^m2 and greater than or equal to 12 g/ ^m2 .

Note 171. The filter media of any preceding note, wherein the open support layer is formed by a spunbond process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns.

Note 172. The filter media of any preceding note, wherein the open support layer is formed by a melt blowing process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 10 microns.

Note 173. The filter medium of any preceding note, wherein the open support layer is a mesh and comprises a plurality of wires having an average wire diameter greater than or equal to 500 microns and less than or equal to 2 mm.

Note 174. The filter media of any preceding note, wherein the open support layer is a mesh having a thread count along the first axis of greater than or equal to 2 threads/inch and less than or equal to 27 threads/inch.

Note 175. The filter media of any preceding note, wherein the open support layer is a mesh having a count of threads along the first axis greater than or equal to 3 threads/inch and less than or equal to 20 threads/inch.

Note 176. The filter medium of any preceding note, further comprising an additional layer.

Additional Note 177. The filter media of additional note 40, wherein the additional layer is a meltblown layer, a spunbond layer, or a carded fiber layer.

Note 178. The filter media of any preceding note, wherein the additional layer has a basis weight of greater than or equal to 3 gsm and less than or equal to 100 gsm.

Note 179. The filter media of any preceding note, wherein the additional layer and the open support layer have a combined basis weight greater than or equal to 10 gsm and less than or equal to 140 gsm.

Note 180. The filter media of any preceding note, wherein the additional layer has an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 20 microns.

Note 181. The filter media of any preceding note, wherein the additional layer has an air permeability greater than or equal to 45 CFM and less than 1100 CFM.

Note 182. The filter media of any preceding note, wherein the additional layer is charged.

Note 183. The filter media of any preceding note, wherein the additional layer is uncharged.

Note 184. The filter media of any preceding note, wherein the charged fibrous layer is mechanically attached to the open support layer and/or the additional layer.

Note 185. The filter medium of any preceding note, wherein mechanically attaching comprises needling.

Note 186. The filter media of any preceding note, wherein the charged fibrous layer is needled to the open support at a perforation density of greater than or equal to 1.5 perforations/cm2 and less than or equal to 60 perforations/cm2 layer.

Note 187. The filter media of any preceding note, wherein the charged fibrous layer is needled to the open support layer with a needle penetration depth of greater than or equal to 8 mm and less than or equal to 20 mm.

Note 188. The filter media of any preceding note, wherein the first polymer is acrylic.

Note 189. The filter media of any preceding note, wherein the charged fibrous layer comprises a plurality of fibers having an average fiber diameter less than 15 microns and greater than or equal to 1 micron.

Note 190. The filter media of any preceding note, wherein the charged fibrous layer has an air permeability greater than or equal to 10 CFM and less than or equal to 1200 CFM.

Note 191. The filter media of any preceding note, wherein the charged fibrous layer has a basis weight of greater than or equal to 10 g/ ^m2 and less than or equal to 600 g/ ^m2 .

Note 192. The filter media of any preceding note, wherein the charged fibrous layer has a basis weight of less than or equal to 12 g/ ^m2 and greater than or equal to 250 g/ ^m2 .

Note 193. The filter media of any preceding note, wherein the first polymer and the second polymer have different dielectric constants.

Note 194. The filter media of any preceding note, wherein the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 0.8 and less than or equal to 8.

Note 195. The filter media of any preceding note, wherein the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 1.5 and less than or equal to 5.

Note 196. The filter medium of any preceding note, wherein the second polymer comprises a synthetic material selected from the group consisting of polypropylene, dry spun acrylic, polyvinyl chloride, modified acrylic, wet spun acrylic , polytetrafluoroethylene, polypropylene, polystyrene, polysulfone, polyethersulfone, polycarbonate, nylon, polyurethane, phenolic resin, polyvinylidene fluoride, polyester, polyaramid, polyimide, poly Olefins, Kevlar, Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, polymethylpentene, and combinations thereof.

Note 197. The filter media of any preceding note, wherein the second polymer is polypropylene.

Note 198. The filter media of any preceding note, wherein the second polymer is present in an amount greater than or equal to 10 wt % and less than or equal to 90 wt % relative to the total weight of the charged fibrous layer in In the charged fiber layer.

Note 199. The filter media of any preceding note, wherein the second polymer is present in an amount greater than or equal to 25 wt % and less than or equal to 75 wt % relative to the total weight of the charged fibrous layer In the charged fiber layer.

Note 200. The filter media of any preceding note, wherein the second polymer is present in an amount greater than or equal to 35 wt % and less than or equal to 65 wt % relative to the total weight of the charged fibrous layer in In the charged fiber layer.

Note 201. The filter medium of any preceding note, wherein the first polymer comprises a synthetic material selected from the group consisting of: polypropylene, dry spun acrylic, polyvinyl chloride, modified acrylic, wet spun acrylic , polytetrafluoroethylene, polypropylene, polystyrene, polysulfone, polyethersulfone, polycarbonate, nylon, polyurethane, phenolic resin, polyvinylidene fluoride, polyester, polyaramid, polyimide, poly Olefins, Kevlar, Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, polymethylpentene, and combinations thereof.

Note 202. The filter media of any preceding note, wherein the first polymer is a dry spun acrylic.

Note 203. The filter media of any preceding note, wherein the first polymer is present in an amount greater than or equal to 10 wt % and less than or equal to 90 wt % relative to the total weight of the charged fibrous layer in In the charged fiber layer.

Note 204. The filter media of any preceding note, wherein the first polymer is present in an amount greater than or equal to 25 wt. % and less than or equal to 75 wt. In the charged fiber layer.

Note 205. The filter media of any preceding note, wherein the first polymer is present in an amount greater than or equal to 35 wt % and less than or equal to 65 wt % relative to the total weight of the charged fibrous layer in In the charged fiber layer.

Note 206. The filter media of any preceding note, wherein the first plurality of fibers has an average fiber diameter less than 15 microns and greater than or equal to 1 micron.

Note 207. The filter media of any preceding note, wherein the second plurality of fibers has an average fiber diameter less than 15 microns and greater than or equal to 1 micron.

Note 208. The filter media of any preceding note, wherein the charged fibrous layer has an uncompressed thickness of greater than or equal to 5 mils and less than or equal to 600 mils, or greater than or equal to 30 mils and less than or equal to 350 mils mil.

Note 209. The filter media of any preceding note, further comprising a coarse support layer that maintains the charged fiber layer in a wave-shaped configuration and maintains separation of peaks and troughs of adjacent waves of the charged fiber layer.

Note 210. The filter medium of any preceding note, wherein the filter medium has a total air permeability of greater than or equal to 10 CFM and less than or equal to 1100 CFM.

Note 211. The filter medium of any preceding note, wherein the filter medium has a total basis weight greater than or equal to 12 g/ ^m2 and less than or equal to 700 g/ ^m2 .

Note 212. The filter medium of any preceding note, wherein the filter medium has a total basis weight greater than or equal to 25 g/ ^m2 and less than or equal to 650 g/ ^m2 .

Note 213. The filter media of any preceding note, wherein the filter media has a total thickness of greater than or equal to 5 mils and less than or equal to 2000 mils.

Note 214. The filter media of any preceding note, wherein the filter media has a total thickness of greater than or equal to 30 mils and less than or equal to 350 mils.

Claims (27)

1. A filter medium comprising: open support layer; and a charged fiber layer mechanically attached to said open support layer, wherein the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer, wherein the first polymer is acrylic, and Wherein the air permeability of the open support layer is greater than 1100 CFM and less than or equal to 20000 CFM. 2. A filter medium comprising: open support layer; and a charged fiber layer mechanically attached to said open support layer, wherein the charged fibrous layer comprises a plurality of fibers having an average fiber diameter less than 15 microns and greater than or equal to 1 micron, and Wherein the air permeability of the open support layer is greater than 1100 CFM and less than or equal to 20000 CFM. 3. The filter media of claim 2, wherein the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer. 4. The filter media of claim 1, wherein the first polymer and the second polymer have different dielectric constants. 5. The filter media of claim 1, wherein the second polymer comprises a synthetic material selected from the group consisting of polypropylene, dry spun acrylic, polyvinyl chloride, modified acrylic, wet spun acrylic, poly Tetrafluoroethylene, polypropylene, polystyrene, polysulfone, polyethersulfone, polycarbonate, nylon, polyurethane, phenolic resin, polyvinylidene fluoride, polyester, polyaramid, polyimide, polyolefin, Kevlar, Nomex, halogenated polymers, polyacrylics, polyphenylene ether, polyphenylene sulfide, and combinations thereof. 6. The filter media of claim 1, wherein the second polymer is polypropylene. 7. The filter media of claim 1, wherein the first polymer is a dry spun acrylic. 8. The filter media of claim 1, wherein the charged fibrous layer is needle punched to the open support layer. 9. The filter media of claim 1, wherein the charged fibrous layer is needled to the open support layer at a perforation density of greater than or equal to 15 perforations/cm2 and less than or equal to 60 perforations/cm2. 10. The filter media of claim 1, wherein the charged fibrous layer is needled to the open support layer with a needle penetration depth of greater than or equal to 8 mm and less than or equal to 20 mm. 11. The filter media of claim 1, wherein the open support layer is formed by a spunbond process and comprises a plurality of fibers having an average fiber diameter greater than or equal to 10 microns and less than or equal to 20 microns. 12. The filter media of claim 1, wherein the open support layer is a mesh and comprises a plurality of wires having an average wire diameter greater than or equal to 500 microns and less than or equal to 2 mm. 13. The filter media of claim 1, wherein the filter media has a total basis weight of greater than or equal to 12 g/ ^m2 and less than or equal to 700 g/ ^m2 . 14. The filter media of claim 1, wherein the filter media has a total air permeability of greater than or equal to 30 CFM and less than or equal to 1100 CFM. 15. The filter media of claim 1, wherein the filter media has an initial efficiency of greater than or equal to 50% and less than or equal to 99.999%. 16. A filter medium comprising: An open support layer with an air permeability greater than 1100CFM and less than or equal to 20000CFM; a charged fibrous layer mechanically attached to the open support layer, wherein the charged fibrous layer comprises a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer; an additional layer associated with the open support layer and the charged fibrous layer; and Wherein the combined air permeability of the open support layer and the additional layer is greater than 45 CFM and less than 1100 CFM. 17. The filter media of claim 16, wherein the additional layer is selected from a meltblown layer, a spunbond layer, or a carded layer. 18. The filter media of claim 16, wherein the open support layer is a mesh. 19. The filter media of claim 16, wherein the open support layer is a spunbond layer. 20. The filter media of claim 16, wherein the additional layer has an average fiber diameter greater than or equal to 0.5 microns and less than or equal to 20 microns. 21. The filter media of claim 16, wherein the charged fibrous layer is needle punched to the open support layer and/or the additional layer. 22. The filter media of claim 16, wherein the charged fibrous layer is needled to the open support layer at a perforation density of greater than or equal to 1.5 perforations/cm2 and less than or equal to 60 perforations/cm2. 23. The filter media of claim 16, wherein the charged fibrous layer is needled to the open support layer at a needle penetration depth of greater than or equal to 8 mm and less than or equal to 20 mm. 24. The filter media of claim 16, wherein the difference in dielectric constant between the first polymer and the second polymer is greater than or equal to 0.8 and less than or equal to 8. 25. The filter media of claim 16, wherein the open support layer has an air permeability greater than or equal to 2500 CFM and less than or equal to 20000 CFM. 26. The filter media of claim 16, including a support layer that maintains at least the charged fiber layer in a wave configuration and maintains separation of peaks and troughs of adjacent waves of the charged fiber layer. 27. The filter media of claim 26, wherein the support layer extends across the peaks and into the valleys to substantially fill the valleys.

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