JPWO2019004477A1 - Functional non-woven fabric - Google Patents

Abstract

A non-woven fabric body (11) in which fibers (11a) are assembled, a plurality of graft chains (20) formed on the fibers (11a), and a functional group (21) attached to the graft chains (20), Provided is a functional non-woven fabric having a diameter of (11a) of 3.0 μm or less.

Description

The present invention relates to a functional nonwoven fabric having a specific function such as antibacterial and deodorant.
The present application claims priority to Japanese Patent Application No. 2017-129718 filed in Japan on June 30, 2017, the contents of which are incorporated herein by reference.

In recent years, attention has been focused on a fibrous body obtained by modifying fibers to have specific functions such as antibacterial, deodorizing (deodorizing), and removal of harmful substances. Specifically, the surface of a natural fiber such as cotton is activated by graft polymerization using an electron beam, and a substance having the above-mentioned function is bonded to the activated fiber surface to give a specific fiber to the fiber. It is given a function (see Patent Documents 1 and 2 below).

JP 2001-164467 A JP 2002-339187 A

By the way, when it is attempted to bind a necessary amount of a chemical agent to a natural fiber such as cotton, the amount of the fiber is increased in order to support the required amount of the functional substance depending on the function to be imparted to the fiber. You may have to do it. That is, the amount of material carried by the fibers is proportional to the surface area of the fibers, but since each natural fiber is thick, the amount of fibers must be increased in order to increase the surface area of the fibers. For example, in the case of a sheet-shaped fiber cut into a certain size, in order to increase the surface area of the fiber while maintaining the size, the sheet has to be thickened to increase the amount of the fiber. However, if the amount of fibers is increased in such a manner, there is a problem that the air permeability is lowered due to the increase in thickness, or the weight of the sheet is increased and the handling becomes inconvenient.

The present invention has been made in view of the above circumstances, without increasing the thickness and weight, further increasing the surface area of the fiber while reducing the thickness and weight, to carry the required amount of the functional substance. An object is to provide a non-woven fabric that can be made.

An aspect of the present invention includes a nonwoven fabric body in which fibers are aggregated, a plurality of graft chains formed on the fibers, and a functional group provided on the graft chains, and the diameter of the fibers is 3.0 μm or less. It is a functional nonwoven fabric.

According to the present invention, although the apparent size is equal to or smaller than the conventional one, and the surface area of the fiber is expanded and the graft chain fixed to the expanded surface is obtained. Since more functional groups having a desired function are provided than in the conventional case, the effectiveness of the functions of the provided functional groups required for the nonwoven fabric can be enhanced.

It is a cross-sectional schematic diagram which shows 1st embodiment of the functional nonwoven fabric concerning this invention. It is a figure which shows an example of the manufacturing apparatus of the nanofiber which comprises a functional nonwoven fabric. It is a cross-sectional schematic diagram which shows the modification of 1st embodiment of the functional nonwoven fabric concerning this invention. It is a cross-sectional schematic diagram which shows 2nd embodiment of the functional nonwoven fabric concerning this invention. It is a graph showing the relationship between the specific surface area of the fiber which comprises the functional nonwoven fabric concerning this invention, and an average fiber diameter. It is a graph which shows the protein adsorption amount per unit area in the some functional nonwoven fabric which changed the state of the functional group membrane. It is a graph which shows the relationship between the graft ratio of a graft chain in a functional nonwoven fabric, and the adsorption amount of wheat germ protein. 1 is a schematic diagram of an experimental device including an aerosol chamber. It is a graph showing the relationship between the basis weight and thickness of a functional nonwoven fabric.

(First embodiment)
1st Embodiment of the functional nonwoven fabric concerning this invention is shown in FIG.
The functional nonwoven fabric 1A in the first embodiment includes a base material 10 and a nonwoven fabric body 11. The nonwoven fabric body 11 is an assembly of ultrafine fibers 11a generally called nanofibers (hereinafter, in the present embodiment, the ultrafine fibers 11a are referred to as nanofibers, and the nonwoven fabric body 11 adhered to the base material 10 is referred to as a nanofiber layer. ). The base material 10 is adhered to the nonwoven fabric body 10 to support the nonwoven fabric body 11 and maintain the rigidity of the nonwoven fabric 1A. A plurality of graft chains 20 are formed on the surface of the nanofiber 11 a, and a plurality of functional groups 21 having a specific function are provided so as to be entangled with the graft chains 20.

(Base material)
The substrate 10 in the present embodiment includes, for example, a dry non-woven fabric, a wet process non-woven fabric, a spun bond non-woven fabric, a thermal bond non-woven fabric, a chemical bond non-woven fabric, a needle punch non-woven fabric, a spun lace non-woven fabric, a stitch bond non-woven fabric, a steam jet non-woven fabric, and the like. A known non-woven fabric can be adopted.
Examples of the material of the base material 10 include polyolefin including polyethylene and polypropylene, rayon, polyester, polyamide, acrylic fiber, vinylon, aramid fiber, glass fiber, and cellulose fiber. The base material 10 may be formed of only one of these materials, or the base material 10 may be formed by mixing two or more materials.
The material of the base material 10 is not particularly limited, but the characteristics required for products to be supplied to the market (for example, in the case of a mask, the trapping property of particles that should be repelled in the air and the ventilation that affects breathability). Various physical properties required for the base material 10 (particle collection efficiency, pressure loss, thickness, porosity, etc.) are naturally specified in accordance with the property). Generally, a mask is required to have air permeability. Therefore, as long as there is no problem in handling and strength during processing, the substrate 10 is desired to be thin, have a large porosity, and have good air permeability.

The shape of the fibers of the non-woven fabric forming the base material 10 is a known one such as one obtained by spinning a resin as a material into a fiber shape, one formed into a film and then split into a mesh shape and processed into a flat fiber, and the like. The shape can be adopted. The average fiber diameter is preferably 100 μm or less, more preferably 30 μm or less, and particularly preferably 3 μm or less.
The porosity of the base material 10 is not particularly limited, but is preferably 80% or more. As will be described later, when particles having a particle diameter in the range of 0.3 μm or more and 0.374 μm or less are to be captured, the QF value obtained from the following formula (1) is 0.010 Pa ⁻¹ or more. preferable.

In this embodiment, the specific surface area of the base material 10 is preferably 0.01 m ² /g or more and 1.0 m ² /g or less. The specific surface area is the size of the surface area per unit mass, and in the present embodiment, it means the size of the surface area with respect to the space occupied by the base material 10.
Further, the air permeability as a scale for measuring the air permeability of the substrate 10 is preferably 10 cm ³ /cm ² ·s or more and 2000 cm ³ /cm ² ·s or less. In the present embodiment, the air permeability of the nonwoven fabric 1A was measured using a Frazier type tester compliant with JIS L1096.

In the present embodiment, the basis weight of the base material 10 is preferably 50 g/m ² or less, and more preferably 30 g/m ² or less. When the basis weight of the base material 10 is equal to or less than the above value, it is possible to suppress the reduction in the air permeability of the mask as a product.

(Nonwoven fabric body)
The nanofibers forming the nanofiber layer 11 as the non-woven fabric body are those obtained by processing a resin as a material into fibers having an average diameter of less than 1 μm.
The resin that can be used as the material of the nanofibers 11a is a thermoplastic resin that can be processed into a thread shape. For example, polyethylene terephthalate, polyester containing polylactic acid, polyamide containing nylon (nylon 6, nylon 66), polypropylene, polyolefin containing polyethylene, polyvinyl alcohol polymer, acrylonitrile polymer, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer Fluorine-based polymers including (PFA), urethane-based polymers, vinyl chloride-based polymers, styrene-based polymers, (meth)acrylic-based polymers, polyoxymethylene, ether ester-based polymers, cellulose modified polymers such as triacetyl cellulose, etc. are used. It is possible. Among them, polyethylene terephthalate, polylactic acid, nylon (nylon 6, nylon 66) and polypropylene are preferable because they have good stretchability and molecular orientation.

The average fiber diameter of the nanofibers 11a in this embodiment is preferably 0.5 μm or less. The basis weight of the nanofiber layer 11 is preferably 0.5 g/m ² or more and 10 g/m ² or less. In particular, the upper limit value of the basis weight is more preferably 6 g/m ² or less, further preferably 3 g/m ² or less. By maintaining the basis weight of the nanofiber layer 11 in the above range, it is possible to suppress a decrease in the air permeability of the nonwoven fabric 1A as a product.

In this embodiment, the porosity of the nanofiber layer 11 obtained from the following formula (2) is preferably 90% or more, and more preferably 95% or more. The resin density (g/cm ³ ) refers to the material density of the resin forming the nanofiber layer 11, and the thickness (μm) refers to the thickness of the nanofiber layer 11. When the porosity of the nanofiber layer 11 is equal to or more than the above value, an increase in pressure loss, which is a factor affecting the air permeability of the mask, is suppressed, and a higher QF value can be maintained. When particles having a particle diameter in the range of 0.3 μm or more and 0.374 μm or less are to be captured, the QF value obtained from the formula (1) is preferably 0.020 Pa ⁻¹ or more. The specific surface area of the nanofiber layer 11 is preferably 1.0 m ² /g or more and 10.0 m ² /g or less. The larger the specific surface area, the more the adsorption sites for harmful substances and the higher the functionality. The air permeability of the nonwoven fabric 1A including the nanofiber layer 11 is preferably 3.0 cm ³ /cm ² ·s or more and 300 cm ³ /cm ² ·s or less. The higher the air permeability, the easier the transfer of harmful substances to the adsorption site.

The nanofiber layer 11 in the present embodiment contains fibers having a fiber diameter of 2 to 10 times the average fiber diameter (less than 1 μm) of the constituent fibers (that is, relatively thick fibers) in a predetermined ratio. Is preferred. Specifically, in the nonwoven fabric of the present invention, it is preferable that fibers having a fiber diameter of 2 times to 10 times the average fiber diameter account for 2 to 20% of the total number of fibers. As a result, the nonwoven fabric of the present invention, when used as a material for a mask, realizes sufficient collection efficiency in practical use, and has a higher air permeability than conventional nanofiber nonwoven fabrics, thus reducing pressure loss. It is possible to improve and prolong the life of the product.

(Graft chain)
The graft chain 20 is a graft polymer arranged like branches on the surface of the nanofiber 11a serving as a trunk. By fixing the graft chains 20 on the surface of the fibers, countless branches of the graft chains 20 are formed in layers on the surface of the fibers (regardless of the fiber diameter) forming the nanofiber layer 11. In the present embodiment, the graft ratio of the graft chain obtained from the following formula (3) is preferably 1% or more and 300% or less. In formula (3), W ₀ refers to the weight of the nonwoven fabric (including the base material) before the graft polymerization, and W refers to the weight of the nonwoven fabric (including the base material) after the graft polymerization.

(Functional group)
In the non-woven fabric 1A of the present embodiment, utilization as a material of a mask particularly effective for capturing influenza virus has been studied, and in order to impart such a function, the functional group 21 imparted to the graft chain 20 is Is a sugar such as sialic acid. In addition to sialic acid, N-acetylglucosamine, sialylgalactose, sialyllactose and the like are particularly effective functional groups for capturing influenza virus. When imparting these functional groups containing sialic acid to the graft chain 20, the graft ratio of the nonwoven fabric 1A is preferably 1% or more and 60% or less. Since the influenza virus is 80 to 120 nm, which is larger than sialic acid, it is not necessary to make the graft chains 20 excessively dense, but if the graft chains 20 are formed only coarser than the size of the influenza virus, the so-called sugar cluster effect will occur. It becomes thin and it becomes difficult to adsorb the virus.

By the way, in the non-woven fabric 1A of the present embodiment, in addition to the capture of influenza virus, it is possible to impart functions such as capture of swine epidemic diarrhea virus, virus sensor, protein capture, trimethylsilanol removal, and deodorization. is there.
When the nonwoven fabric 1A is provided with a swine epidemic diarrhea virus trapping function, a peptide that mimics the binding site of aminopeptidase N to the swine epidemic diarrhea virus is used as the functional group 21 attached to the graft chain 20. .. When imparting these functional groups to the graft chain 20, the graft ratio of the nonwoven fabric 1A is preferably 1% or more and 60% or less, and more preferably 20% or more and 55% or less. As with the influenza virus, swine pandemic diarrhea virus is larger than sialic acid, so it is not necessary to overpopulate the graft chains 20, but the graft chains 20 form only coarser than the size of the swine pandemic diarrhea virus. Otherwise, it will be difficult to adsorb the virus.

When imparting the function of a virus sensor to the nonwoven fabric 1A, sialic acid, N-acetylglucosamine, sialylgalactose, sialyllactose, or the like is used as the functional group 21 imparted to the graft chain 20. When imparting these functional groups to the graft chain 20, the graft ratio of the nonwoven fabric 1A is preferably 1% or more and 60% or less, and more preferably 20% or more and 55% or less. In order to express the sensing function, it is necessary to increase the amount of adsorbed virus, but it is not necessary to make it excessively dense.
When the nonwoven fabric 1A is provided with a protein trapping function, the functional group 21 provided on the graft chain 20 is the above-mentioned sugar, peptide or the like. Since proteins are as small as one-tenth or less the size of viruses, when these functional groups are added to the graft chain 20, the graft ratio of the nonwoven fabric 1A is preferably 30% or more and 300% or less.
When imparting the trimethylsilanol removing function to the non-woven fabric 1A, sulfonic acid, carboxylic acid, phosphoric acid or the like is used as the functional group 21 provided to the graft chain 20. When imparting these functional groups to the graft chain 20, the graft ratio of the nonwoven fabric 1A is preferably 50% or more and 300% or less, and more preferably 60% or more and 250% or less. Trimethylsilanol is dimerized with an acid catalyst and can be removed with an activated carbon filter or the like. Since trimethylsilanol is a small compound with a molecular weight of 90.2, it can diffuse between high-density graft chains, and many sulfonic acid groups, which serve as acid catalyst active sites, are provided on the nonwoven fabric surface. Is preferred. On the other hand, even if the graft ratio is excessively increased, a graft chain is formed not inside the nonwoven fabric surface but inside the fiber, and does not function as an active site.
When imparting a deodorizing function to the nonwoven fabric 1A, a sulfonic acid, a carboxylic acid, a phosphoric acid, a metal complex, an amine or the like is used as the functional group 21 provided to the graft chain 20. When imparting these functional groups to the graft chain 20, the graft ratio of the nonwoven fabric 1A is preferably 50% or more and 300% or less, and more preferably 60% or more and 250% or less. Odorous components such as hydrogen sulfide and ammonia are compounds with a small molecular weight, so they can diffuse between high-density graft chains, and many functional groups serving as adsorption sites are provided on the nonwoven fabric surface. Is preferred. On the other hand, even if the graft ratio is excessively increased, a graft chain is formed not inside the nonwoven fabric surface but inside the fiber, and does not function as an adsorption site.

According to the functional non-woven fabric 1A configured as described above, although the apparent size is thinner and lighter than the conventional one, the surface area of the fiber is expanded and the fiber is fixed on the expanded surface. Since the graft chain 20 is provided with more functional groups 21 having a desired function than in the conventional case, the functional effectiveness of the functional nonwoven fabric 1A can be enhanced.

<Method for producing functional nonwoven fabric>
The method for producing a functional nonwoven fabric according to the present embodiment includes a step of generating nanofibers, a step of forming the nanofiber layer 11 on the base material 10 so that the basis weight is 10 g/m ² or less, and The method includes a step of forming the graft chain 20 on the surface of the nanofibers forming the nanofiber layer 11, and a step of imparting a functional group 21 to the graft chain 20.

(Nanofiber production process)
A conventionally known method can be used for producing the nanofibers. For example, an electrospinning method (electrospinning method), a melt blow method, a sea-island melt spinning method, a carbon dioxide gas supersonic laser stretching method and the like can be mentioned. Among them, the carbon dioxide gas supersonic laser drawing method can be applied to (1) a thermoplastic polymer material, (2) the obtained nanofibers are infinitely long fibers, and (3) the fiber orientation is high, 4) The working environment and safety of nanofibers are high because no solvent is used, (5) Nanofibers can be prevented from scattering because the fibers are collected by reducing the pressure, and (6) The device has a small and simple structure. Therefore, it is preferable because it can be installed anywhere and has excellent expandability.

Hereinafter, a preferred example of the nanofiber production step in the present embodiment will be described.
The nanofibers are produced using an apparatus in which the original filament delivery means and the drawing chamber are connected via a nozzle and the pressure difference between the inlet and outlet of the nozzle is 20 kPa or more. That is, the original filament delivery means delivers the original filament, and the delivered original filament passes through the nozzle and is guided to the drawing chamber. In the drawing chamber, the original filament coming out from the nozzle is irradiated with laser. As a result, the original filament is continuously melted and drawn to produce nanofibers.

In this embodiment, a multi-filament yarn (multi-filament) is used as the original filament. Therefore, hereinafter, the original filament may be referred to as a multifilament. The multi-filament yarn (multi-filament) refers to a bundle composed of a plurality of mono-filament yarns (monofilaments). The cross-sectional shape of one monofilament forming the multifilament is not particularly limited. That is, the monofilament may be not only a circular cross-sectional shape but also various deformed original yarns having a cross-sectional shape of an ellipse, a quadrangle, a triangle, a trapezoid, and other polygons. Further, as the monofilament, a composite yarn such as a hollow fiber, a core-sheath type yarn or a side-by-side type yarn may be used. Further, the monofilaments that make up the multifilament need not all be the same. A multifilament may be configured by combining monofilaments having different shapes and materials.

In the present embodiment, a multifilament in which 10 or more monofilaments are bundled is used as an original filament. The resin that can be used as the multifilament is the same as the material described above as the material of the nanofiber 11a. The number of monofilaments bundled can be adjusted according to the nozzle used. Specifically, the ratio (S2/S1) of the total cross-sectional area S2 of the multifilament to the cross-sectional area S1 of the rectifying portion of the nozzle can be appropriately adjusted so as to fall within an appropriate range. A multifilament in which 20 or more, more preferably 40 or more monofilaments are bundled is used as the original filament. Further, the diameter of each monofilament constituting the multifilament is preferably 10 to 200 μm. The multifilament is usually twisted so that a plurality of monofilaments does not lose their unity as a bundle. The number of twists is appropriately adjusted depending on the number of monofilaments, shape, material, etc. (usually 20 times/m or more).

The multifilament may be one in which various substances such as various organic substances, organometallic complexes, and inorganic substances are kneaded into the fiber, or adhered to the surface of the fiber. As a result, when the nanofibers are produced, the substance that has been kneaded and/or attached can be uniformly dispersed to impart functionality to the nanofibers.

FIG. 2 shows an example of an apparatus for producing nanofibers according to this embodiment. The original filament supply chamber C1 and the drawing chamber C2 are connected via a nozzle 30. An original filament delivery device 25 that delivers the original filament (multifilament) toward the nozzle 30 is provided on the upstream side of the original filament supply chamber C1. The raw filament delivery device 25 is not particularly limited in its configuration and the like as long as it can deliver the multifilaments at a constant delivery speed. Hereinafter, the original filament delivery device 25 and the original filament supply chamber C1 may be collectively referred to as "original filament delivery means".

The nozzle 30 has an inner surface that is tapered to have an inner diameter that decreases toward the downstream side, and a straight tubular straightening section 32 that has a uniform inner diameter and that is formed continuously with the downstream end of the introducing section 31. It is preferable to have and.
The ratio (L/D) of the length L of the rectifying section 32 and the diameter D of the rectifying section 32 is preferably 1 to 100, more preferably 1 to 50, and further preferably 1 to 10. The rectifying section 32 may be appropriately subjected to air flow adjusting processing or the like depending on the number, shape, material, etc. of the monofilaments in the multifilaments used.

The original filament supply chamber C1 is under the atmosphere of P1 atmospheric pressure. On the other hand, the stretching chamber C2 is kept in an atmosphere of P2 atmospheric pressure lower than P1 atmospheric pressure. Due to the pressure difference (P1-P2) between the original filament supply chamber C1 at P1 atmosphere and the stretching chamber at P2 atmosphere, the nozzle 30 is moved from the inlet (introduction part 31) of the nozzle to the outlet (downstream end of the rectifying part 32). An oncoming air flow is created. The multifilament sent to the nozzle 30 is sent to the drawing chamber C2 through the nozzle 30 by the air flow generated in the nozzle 30.
Note that P1≧2×P2 is preferable, P1≧3×P2 is further preferable, and P1≧5×P2 is most preferable. Further, specifically, the pressure difference (P1-P2) between P1 and P2 is preferably 20 kPa or more, and more preferably 50 kPa or more.

In the present embodiment, it is particularly preferable that P1 be atmospheric pressure and P2 be a pressure lower than atmospheric pressure. This is because the device can be configured relatively easily. The temperatures of the original filament supply chamber C1 and the drawing chamber C2 are usually room temperature (normal temperature). However, when it is desired to preheat the multifilament or to heat-treat the filament after drawing, heated air can be appropriately used. An inert gas such as nitrogen gas may be used to prevent the filaments from being oxidized. A vapor containing water vapor or a gas containing water may be used to prevent the scattering of water.
Also, various other inert gases may be used for the purpose of controlling the vibration of the multifilament (described later).

In the present embodiment, in order to generate a sufficient air flow to send the multifilament to the drawing chamber C2, the ratio of the total cross sectional area S2 of the multifilament to the cross sectional area S1 of the straightening portion 32 of the nozzle 30 (=S2/ S1, hereinafter referred to as "nozzle rectification unit occupancy rate") must be 50% or less. If the nozzle rectification unit occupancy rate (S2/S1) is greater than 50%, the amount of high-speed airflow flowing in the rectification unit 32 will be insufficient, and vibration of the multifilament (described later) cannot be sufficiently obtained. is there. If the vibration of the multifilament is insufficient, the melted multifilament does not form a thread and falls as a molten mass, so that nanofibers cannot be obtained. On the other hand, if the nozzle rectification unit occupancy rate (S2/S1) is less than 5%, the vibration of the multifilament becomes too large, or the force of the air flow does not apply well to the multifilament, and the desired nanofiber is obtained. I can't. Therefore, the nozzle rectification unit occupancy (S2/S1) needs to be 5 to 50%, and is preferably 10 to 35%.

Laser irradiation is performed on the multifilament that has passed through the nozzle 30, and the tip of the multifilament is heated and melted. At this time, it is necessary to generate vibration in the multifilament, and for that reason, laser irradiation conditions such as laser irradiation position, laser shape, and laser power are adjusted appropriately.

In order to obtain nanofibers from the multifilament, it is necessary to vibrate the multifilament by laser irradiation, but it is not necessary to simply vibrate the multifilament. In order to stably obtain the desired nanofiber, the angle of the multifilament (the center of the bundle) during vibration (hereinafter referred to as the “vibration angle of the multifilament”) with respect to the central axis of the nozzle 30 is 5° to 80°. Must be in the range. The vibration angle of the multifilament is preferably in the range of 15° to 50°, more preferably in the range of 20° to 40°.

Further, in order to generate vibration in the multifilament, the position of laser irradiation is also important. Specifically, it is necessary to perform laser irradiation so that the center position of the molten portion of the multifilament is 1 mm or more and 15 mm or less vertically below the nozzle exit. If the melted portion of the multifilament is closer than 1 mm from the nozzle outlet, the vibration angle of the multifilament may exceed the upper limit of the above range due to the air flow flowing out of the nozzle, and the melted portion of the multifilament is If the distance is more than 15 mm from the outlet, the airflow flowing out of the nozzle is weakened, and the vibration angle of the multifilament may be below the lower limit of the above range. Preferably, the laser irradiation is performed such that the center position of the melted portion of the multifilament is 3 mm or more and 10 mm or less vertically below the nozzle outlet, and more preferably, the laser irradiation is performed at the center position of the melted portion of the multifilament. Is performed at a position 3 mm or more and 5 mm or less vertically below the nozzle outlet.
When vibration occurs in the multifilament satisfying the above-mentioned conditions, nanofiber is generated.

In the above process, the original filament (multifilament) used, the delivery speed of the original filament (multifilament), the nozzle shape, the laser irradiation conditions, and/or the pressure difference (P1) between the original filament supply chamber and the drawing chamber. By changing -P2), it is possible to adjust the average fiber diameter and the fiber diameter distribution of the obtained nanofibers. For example, in the case of producing the nanofiber for the air filter of the present embodiment, a fiber having a fiber diameter of 2 to 10 times the average fiber diameter of the constituent fibers (relatively thick fiber) in the constituent fibers. Of the original filament, the delivery speed of the original filament, the nozzle shape, the laser irradiation condition, and/or the pressure difference (P1−P2) are selected or determined such that

(Nanofiber layer forming process)
The nanofibers produced in the above steps are deposited on the substrate 10. When forming the nanofiber layer 11, the nanofiber layer 11 is formed by ejecting the nanofiber from the above-mentioned device on one surface of the sheet-shaped base material 10 while feeding the base material 10 in one direction. At this time, the injection amount of the nanofibers and the delivery speed of the base material 10 are appropriately adjusted so that the basis weight of the nanofiber layer 11 is 10 g/m ² or less. In order to efficiently form the generated nanofiber layer 11 on the base material 10, for example, in the above-described device, a plurality of nozzles are arranged in a direction intersecting the moving direction of the base material 10. Good. In this case, the interval between the nozzles is appropriately adjusted so that the vibrating multifilaments do not come into contact with each other and the formed nanofiber film is not adversely affected by the air flow of the adjacent nozzles.

(Graft chain formation step)
Radiation graft polymerization is performed on the nanofiber layer 11 formed in the above process to fix the graft chain 20 on the surface of the fiber 11a forming the nanofiber layer 11. For example, a polymer material such as polypropylene forming nanofibers is irradiated with radiation. In the polymer material irradiated with radiation, C—H bonds are broken and radicals are generated. When a polymer material in which radicals are generated is brought into contact with a solution of glycidyl methacrylate (GMA) having a double bond (vinyl group) (hereinafter referred to as “GMA solution”), the radicals become active species of the reaction and glycidyl. The double bond of the methacrylate is broken to bond with the radical, and the graft chain 20 is formed on the surface of the polymer material. As the solvent of the GMA solution used here, a solvent containing alcohols such as methanol or aromatics such as toluene is used.
In the present embodiment, an example in which a GMA solution is used as the material forming the graft chain 20 has been described, but the present invention is not limited to this. For example, a compound having an unsaturated double bond functional group such as a vinyl group, an allyl group, an acryloyl group or a methacryloyl group may be used, or a compound having an unsaturated triple bond functional group such as a propargyl group may be used. ..

(Functional group application step)
The nonwoven fabric 1A in which the graft chains 20 are formed on the surface of the nanofibers 11a is immersed in a solution containing the functional group 21, and the state is maintained at a predetermined temperature for a predetermined time. Then, when the nonwoven fabric 1A is taken out from the solution, washed and dried, the graft chain 20 is provided with the functional group 21.

(Modification)
A modification of the first embodiment is shown in FIG.
The nonwoven fabric 1B in the present modification example includes two base materials 10 and a nanofiber layer (nonwoven fabric body) 11 sandwiched between them. A plurality of graft chains 20 are formed on the surface of the nanofiber 11 a, and a plurality of functional groups 21 having a specific function are provided so as to be entangled with the graft chains 20.
The materials of the base material 10 and the nanofibers 11a and various physical property values required for them are the same as those in the first embodiment.

(Second embodiment)
A second embodiment of the functional nonwoven fabric according to the present invention is shown in FIG.
In the functional nonwoven fabric 2 according to the second embodiment, an aggregate of fibers 12a generally called microfibers is used as the nonwoven fabric body 12, and a plurality of graft chains 20 are formed on the surface of the fibers 12a constituting the nonwoven fabric body 12, A plurality of functional groups 21 having a specific function are provided so as to be entangled in the chain 20 (hereinafter, the fibers 12a are referred to as microfibers in the present embodiment).

So-called microfibers are those obtained by processing a resin as a material into fibers having an average fiber diameter of less than 3 μm. The resin that can be used as the material of the microfiber 12a is a thermoplastic resin that can be processed into a thread shape. For example, polyethylene terephthalate, polyester containing polylactic acid, polyamide containing nylon (nylon 6, nylon 66), polypropylene, polyolefin containing polyethylene, polyvinyl alcohol polymer, acrylonitrile polymer, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer Fluorine-based polymers including (PFA), urethane-based polymers, vinyl chloride-based polymers, styrene-based polymers, (meth)acrylic-based polymers, polyoxymethylene, ether ester-based polymers, cellulose modified polymers such as triacetyl cellulose, etc. are used. It is possible. Among them, polyethylene terephthalate, polylactic acid, nylon (nylon 6, nylon 66) and polypropylene are preferable because they have good stretchability and molecular orientation.

FIG. 5 is a graph showing the relationship between the specific surface area of the fibers forming the nonwoven fabric and the average fiber diameter. According to this graph, when the average fiber diameter becomes 3 μm or less, the specific surface area rapidly increases. The larger the specific surface area, the larger the number of graft chains (per unit weight) formed on the fiber surface, and the larger the number of functional groups attached to the graft chains. Therefore, the smaller the average fiber diameter of the nonwoven fabric, the higher the effectiveness of the function of the functional group.
The material of the microfibers 12a is not particularly limited, but the characteristics required for products supplied to the market (for example, in the case of a mask, the trapping property of particles that should be repelled in the air, the ventilation that affects the breathability) Various physical properties required for the nonwoven fabric body 12 (particle collection efficiency, pressure loss, thickness, porosity, etc.) are naturally specified in accordance with the properties). Generally, a mask is required to have air permeability. Therefore, as long as there is no problem in handling and strength during processing, the nonwoven fabric body 12 is desired to be thin, have a large porosity, and have good air permeability.

In the present embodiment, the basis weight of the non-woven fabric body 12 that is an assembly of microfibers 12a is 50 g/m ² or less, and preferably 30 g/m ² or less. When the basis weight of the non-woven fabric body 12 is equal to or less than the above value, it is possible to suppress a decrease in air permeability of the mask as a product.
When particles having a particle diameter in the range of 0.3 μm or more and 0.374 or less are to be captured, the QF value obtained from the above formula (1) is preferably 0.010 Pa ⁻¹ or more. The specific surface area of the nonwoven fabric body 12 is preferably 0.01 m ² /g or more and 1.0 m ² /g or less. The nonwoven fabric body 12 preferably has an air permeability of 10 cm ³ /cm ² ·s or more and 2000 cm ³ /cm ² ·s or less. Note that the method of measuring air permeability follows the first embodiment.

Further, in the present embodiment, the porosity of the nonwoven fabric body 12 obtained from the above formula (2) is preferably 80% or more. When the porosity of the nonwoven fabric body 12 is equal to or more than the above value, it is possible to further suppress an increase in pressure loss, which is a factor that influences the air permeability of the mask, and maintain a higher QF value.

According to the functional non-woven fabric 2 configured as described above, the graft chain 20 fixed on the surface of the microfiber 12a is provided with more functional groups 21 having a desired function than in the past. The effectiveness of the function can be increased.

<Protein adsorption experiment>
For the above-mentioned functional nonwoven fabric 1, the amount of adsorbed protein was evaluated by the following method.
(Formation of GMA film)
First, the nonwoven fabric 1A described as the first embodiment of the present invention (base material: polyethylene, fabric weight 18 g/m ² , nanofiber layer: polypropylene nanofiber nonwoven fabric, average fiber diameter 0.3 μm, fabric weight 10 g/m ² ). Was cut into a 5 cm×5 cm square, and its weight was measured. Further, a GMA/methanol mixed solution having a GMA concentration of 10% was prepared, and the nonwoven fabric 1A cut into the above size was put in a bag in which the solution was injected, and the bag was evacuated and immersed in the GMA/methanol mixed solution. After that, while maintaining the vacuumed state of the bag, the nonwoven fabric 1 in the bag was irradiated with radiation to be graft-polymerized. The nonwoven fabric 1A was taken out of the bag and washed with methanol three times and DMF (N,N-dimethylformamide) twice. After washing, the nonwoven fabric 1 was dried to prepare a test piece A. The weight of the test piece A was measured, and the graft ratio was calculated using the above formula (3).

Similarly, a GMA/methanol mixed solution having a GMA concentration of 50%, a GMA/toluene mixed solution having a GMA concentration of 10%, a GMA/toluene mixed solution having a GMA concentration of 50%, and a GMA concentration of 10% liquid were prepared, and those solutions were prepared. The nonwoven fabric 1A was graft-polymerized in the same manner as above. The graft ratio was calculated for each of the test pieces B, C, D, and E of the nonwoven fabric 1A produced using each solution. The results are shown in Table 1.

It can be seen that the higher the GMA concentration of the mixed solution is, the higher the graft ratio of the test piece is, regardless of whether the solvent is methanol or toluene. Moreover, when compared with 50%, which has a high GMA concentration, the graft ratio of the test piece is higher when methanol is used than toluene, and when methanol is used, the graft chain can be extended further on the nanofiber surface. You can

Aside from the above test pieces A to E, the nonwoven fabric 1B described as a modified example of the first embodiment of the present invention (base material: spunbonded nonwoven fabric made of polypropylene, average fiber diameter 20 μm, basis weight 15 g/m ² , nanofiber layer). : A polypropylene nanofiber nonwoven fabric, an average fiber diameter of 0.3 μm, and a basis weight of 6 g/m ² ) are prepared, and the base material used for the nonwoven fabric 1B (polypropylene spunbonded nonwoven fabric, average fiber diameter of 20 μm, and basis weight of 15 g/m ² ). Prepared, and a GMA film was formed on them using three GMA/methanol mixed solutions having different concentrations, and only the test pieces F, G and H of the non-woven fabric 1B and the base material of the non-woven fabric 1B (that is, spunbonded non-woven fabric) were prepared. ) Test pieces I, J and K were prepared as comparative examples.
The graft ratio was calculated for each of the test pieces F to K. The results are shown in Table 2.
Comparing for each GMA concentration, it can be seen that the graft ratio of the test piece of the nonwoven fabric 1B having the nanofiber layer 11 can be higher than that of the test piece of the spunbonded nonwoven fabric.

(Introduction of IDA-EDC into GMA membrane)
Aside from the above test pieces A to K, the nonwoven fabric 1A described as the first embodiment of the present invention (base material: polyethylene nonwoven fabric, basis weight 18 g/m ² , nanofiber layer: polypropylene nanofiber nonwoven fabric, average fiber diameter 0.3 μm and a basis weight of 10 g/m ² ) were prepared, and a GMA film was formed on each of the five solutions having different GMA concentrations to prepare test pieces LP. In addition, 0.125 M of iminodiacetic acid disodium hydrate (hereinafter referred to as “IDA”) as a functional group and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (hereinafter referred to as “EDC”) 0.25 M) was subjected to a coupling reaction at a temperature of 25° C. for 60 hours to prepare an IDA-EDC solution. Then, each test piece L to P was reacted with an IDA-EDC solution to fix the IDA-EDC to the GMA film formed on each surface. Then, the molar conversion ratio of IDA-EDC to the GMA film in each of the test pieces L to P was determined by the following formula (4).

(Introduction of sugar into IDA-EDC membrane)
Immobilizing the IDA-EDC on the GMA film, the test pieces L to P having the IDA-EDC film formed on the surface were immersed in a 0.25 M sialic acid (N-acetylneuraminic acid, NANA) solution. Shake at a temperature of 25° C. for 24 hours. Then, the test pieces LP were taken out from the sialic acid solution, washed with ion-exchanged water, and dried to fix sialic acid on the IDA-EDC membrane formed on the surface of each test piece. Then, the molar conversion rate of sialic acid to the IDA-EDC film in each of the test pieces L to P was determined by the following formula (5).

Similarly, each of the test pieces LP having the IDA-EDC film formed on the surface is immersed in a 0.25 M N-acetylglucosamine (hereinafter, referred to as “GlcNAc”) solution, and the temperature is 25° C. for 24 hours. Shaken for hours. Then, each test piece L to P was taken out from the GlcNAc solution, washed with ion-exchanged water, and dried to fix GlcNAc on the IDA-EDC film formed on the surface of each test piece. Then, the molar conversion ratio of GlcNAc to the IDA-EDC film in each of the test pieces L to P was determined by the following formula (6).

For each of the test pieces L to P, the GMA concentration, the graft rate, the IDA-EDC conversion rate obtained by the equation (4), the sialic acid conversion rate obtained by the equation (5), and the GlcNAc conversion rate obtained by the equation (6). Is shown in Table 3.
Comparing the molar conversion rates of sialic acid to the IDA-EDC membrane for each of the test pieces L to P, no proportional relationship was found between the magnitude of the grafting rate and the sialic acid conversion rate, and the molar conversion rate was 60% or more. Showed a high value of. Further, comparing the molar conversion rates of GlcNAc to the IDA-EDC film, although the test pieces O and P have higher grafting rates than the test pieces M and N, the GlcNAc conversion rates of the test pieces O and P are , Which is lower than the test pieces M and N. From this, when the graft ratio is low, the number of graft chains is small and the number of functional groups fixed on the graph chain is also small, but even if the graft ratio is high and the number of graft chains is too large, the number of functional groups between the graft chains is small. It is speculated that the space that can be accommodated is reduced and the number of functional groups is consequently limited.

(Protein adsorption)
A solution of wheat germ protein, which was likened to hemagglutinin, which is a protein existing on the surface of influenza virus, was prepared to 100 μg/mL, and 1 cm×1 cm squares of the following five samples S1 were cut into 1 mL of the wheat germ protein solution. ~S5 was soaked and shaken at 37°C for 24 hours. Each sample was taken out of the solution, and the amount of wheat germ protein contained in the remaining wheat germ protein solution was quantified by the BCA method.
(S1) Non-woven fabric without graft chain formation (S2) Non-woven fabric with only GMA film (S3) Non-woven fabric with IDA-EDC film (S4) Non-woven fabric with sialic acid fixed to IDA-EDC film (S5) ) Nonwoven fabric in which GlcNAc is fixed to the IDA-EDC film

The amount of wheat germ protein adsorbed to each sample, that is, the amount of wheat germ protein adsorbed per unit area (1 cm×1 cm) was determined from the remaining amount of wheat germ protein in the solution quantified by the BCA method. The result is shown in FIG.
For samples S2, S4, and S5, protein adsorption was observed in each of them. However, although the sample S5 had GlcNAc binding specificity, the protein adsorption amount was between the sample S2 and the sample S4. The reason is that the conversion rate of GlcNAc to the GMA membrane is low, or because the binding site between GlcNAc and wheat germ protein is used for binding between GlcNAc and IDA-EDC, the interaction becomes weak and the glycocluster effect is reduced. It is probable that was not fully exerted.
Sample S4 was adsorbed with an amount of protein equivalent to about four times that of sample S2, and it is considered that the sugar cluster effect of sialic acid was sufficiently exerted.

The relationship between the graft ratio and the amount of wheat germ protein adsorbed is shown in FIG. It can be seen that the adsorbed amount of wheat germ protein per unit area increases as the graft ratio increases.

Aside from the test pieces A to P, the nonwoven fabric 1B described as a modified example of the first embodiment of the present invention (base material: spunbonded nonwoven fabric made of polypropylene, average fiber diameter 20 μm, basis weight 15 g/m ² , nanofiber layer). A plurality of polypropylene nanofiber nonwoven fabrics, average fiber diameter 0.3 μm, and basis weight 6 g/m ² ) were prepared, and GMA films having different graft ratios were formed on them to prepare test pieces U to W.
Further, a plurality of nonwoven fabrics 2 (polypropylene microfiber nonwoven fabric, average fiber diameter 2.2 μm, basis weight 30 g/m ² ) described as the second embodiment of the present invention are prepared, and GMA films having different grafting rates are formed on them. Then, test pieces AA, BB, CC and DD were produced.
As a comparative example of the test pieces U to W, a polypropylene spunbonded non-woven fabric used as a base material of the non-woven fabric 1B was prepared, and a GMA film was formed on the non-woven fabric alone to prepare a test piece X. In addition, a polypropylene nanofiber non-woven fabric used for the nanofiber layer of the non-woven fabric 1B was prepared, and a GMA film was formed on the non-woven fabric unit to prepare a test piece Y.

For each of the above test pieces, IDA-EDC was immobilized on each GMA membrane to form an IDA-EDC membrane, and sialic acid was further immobilized on the IDA-EDC membrane.
Table 4 shows the graft rate of each test piece, the IDA-EDC conversion rate obtained by the equation (4), and the sialic acid conversion rate obtained by the equation (5).
Further, wheat germ protein was adsorbed to each test piece in the above manner. Then, the adsorbed amount of wheat germ protein for each test piece was quantified by the BCA method. Table 4 shows the quantified amount of adsorbed wheat germ protein and the value obtained by dividing the value by the amount of sialic acid, that is, the adsorbed amount of wheat germ protein per unit sialic acid. The amount of wheat germ protein adsorbed per unit of sialic acid is the result of examination on a test piece having a shaking time of 24 hours.

It can be seen that the adsorbed amount of wheat germ protein per unit area increases as the grafting ratio increases, but is not in a proportional relationship. Even if the graft ratio is about 3 times from 52% to 162%, the adsorption amount is 1.3 times or less and less than 2 times. Therefore, even if the graft ratio is excessively increased, many graft chains are not effectively utilized. I see.
Further, when comparing the test pieces U, AA, BB and CC having the graft ratios of 50% each, the test piece Y of the non-woven cloth 1B per unit sialic acid is more than the test piece AA, BB and CC of the non-woven cloth 2. It can be seen that the amount of wheat germ protein adsorbed in is large.
Furthermore, comparing the adsorption amount of wheat germ protein (shaking time: 12 hours) between the test piece U having a grafting rate of 50% and the test piece Y as a comparative example, the test piece U showed two. Adsorbs more than double the amount of protein.

(Protein adsorption in the gas phase)
Separately from the test piece AA, the nonwoven fabric 2 (polypropylene microfiber nonwoven fabric, average fiber diameter 2.2 μm, basis weight 30 g/m ² ) described as the second embodiment of the present invention is prepared and a GMA film is formed. To produce a test piece EE. An IDA-EDC film was formed on the GMA film of the test piece EE, and sialic acid was fixed on the IDA-EDC film. In this test piece AA, the IDA-EDC conversion rate obtained by the equation (4) was 81.4%, and the sialic acid conversion rate obtained by the equation (5) was 37.0%. After placing this test piece EE on the bottom of the nebulizer unit 100 shown in FIG. 8, open the lid 100a of the nebulizer unit 100, drop 100 μL of a 1 μg/μL solution of wheat germ protein into the unit, and close the lid 100a. The aerosol chamber 101 was closed. Then, the suction device 102 was operated to evacuate the chamber 101 to atomize the wheat germ protein solution. After 3 minutes, the test piece EE was taken out from the nebulizer unit 100, washed with ion-exchanged water, immersed in 10 mL of a 0.2 wt% sodium lauryl sulfate aqueous solution, and shaken for 30 minutes. The test piece EE was taken out of the solution, and the amount of wheat germ protein contained in the remaining solution was quantified by the BCA method. The results are also shown in Table 4.

In the test piece EE, the quantified adsorption amount of wheat germ protein was 15.8 μg/cm ² , and the adsorption amount per unit sialic acid was 0.035 g/g. Comparing with other test pieces, it can be seen that even when the protein is adsorbed in the gas phase, the wheat germ protein is adsorbed to the same level as or higher than the adsorption in the liquid phase.

(Thickness per unit weight)
Nonwoven fabric 1B described as a modification of the first embodiment of the present invention (base material: polypropylene spunbonded nonwoven fabric, average fiber diameter 20 μm, basis weight 15 g/m ² , nanofiber layer: polypropylene nanofiber nonwoven fabric, average fiber diameter 0 0.3 μm, areal weight 6 g/m ² ) was prepared (test piece FF), and the weight per unit area weight was measured after measuring the weight per unit area of the test piece. In addition, a plurality of nonwoven fabrics 2 (polypropylene microfiber nonwoven fabric, average fiber diameter 2.2 μm) described as the second embodiment of the present invention are prepared (test pieces GG, HH, II), and the basis weight of each test piece is prepared. Was measured, and then the thickness per unit weight was measured. Furthermore, with respect to the separately prepared test pieces JJ and KK as comparative examples, the weight per unit weight was measured and then the thickness per unit weight was measured. The measurement results are shown in Table 5, and a graph showing the relationship between the areal weight and the thickness is shown in FIG.

Compared with the thickness per unit weight of the test pieces JJ and KK as comparative examples, the thickness per unit weight of the test pieces FF to II was about 1/2. From this, even if the amount of basis weight is the same, the thickness of the nonwoven fabric of the present invention is thinner than that of the conventional product to be compared, and in giving various functions, formation of graft chains, addition of functional groups, etc. Easy to peel off. In addition, when it is processed into daily products such as a mask, it is convenient for the user and has a merit that it is less burdensome to put on the skin.

1A, 1B and 2... Functional non-woven fabric,
10... Base material,
11... Nanofiber layer (nonwoven fabric body),
11a... nanofiber,
12... Microfiber aggregate (nonwoven fabric body),
12a... Microfiber,
20... Graft chain,
21... Functional group

One aspect of the present invention includes a nonwoven fabric body in which fibers are gathered, a base material adhered to the nonwoven fabric body to support the nonwoven fabric body, a plurality of graft chains formed on the fibers and the base material , and the graft. A functional non-woven fabric having a functional group attached to a chain and having a fiber diameter of 3.0 μm or less.
Another aspect of the present invention comprises a step of producing nanofibers, a step of forming a nanofiber layer composed of the nanofibers on a base material, and a step of forming the nanofiber layer formed on the base material. And a step of fixing a plurality of graft chains to the surfaces of the fibers constituting the base material and a surface of the fibers constituting the substrate, and a step of imparting a functional group to the plurality of graft chains.

Claims (11)

A non-woven fabric body in which fibers are gathered, a plurality of graft chains formed on the fibers, and a functional group imparted to the graft chains,
A functional non-woven fabric having an average fiber diameter of 3.0 μm or less. The functional nonwoven fabric according to claim 1, wherein the average diameter of the fibers is 0.5 μm or less. The functional nonwoven fabric according to claim 1 or 2, further comprising a substrate that is adhered to the nonwoven fabric body to support the nonwoven fabric body. The functional nonwoven fabric according to claim 3, wherein the basis weight of the nonwoven fabric body including the substrate is 50 g/m ² or less. The functional non-woven fabric according to claim 1, wherein the non-woven fabric body has a specific surface area of 1.0 m ² /g or more and 10.0 m ² /g or less. Functional nonwoven fabric according to any one of the non-woven fabric air permeability of the body 3.0cm ³ / cm ² · s or more 300cm ³ / cm ² · s or less is claims 3 to 5 comprising said substrate. The functional nonwoven fabric according to claim 1, wherein the basis weight of the nonwoven fabric body is 50 g/m ² or less. The functional nonwoven fabric according to any one of claims 1 to 7, which has a graft ratio of 1% or more and 300% or less. The functional group is any one of sialic acid, N-acetylglucosamine, sialylgalactose, and sialyllactose,
The functional nonwoven fabric according to claim 8, wherein the graft ratio is 1% or more and 60% or less. The functional group is a peptide that mimics the binding site of aminopeptidase N to swine epidemic diarrhea virus,
The functional nonwoven fabric according to claim 8, wherein the graft ratio is 1% or more and 60% or less. The functional group is any of sulfonic acid, carboxylic acid, phosphoric acid, metal complex, amine,
The functional non-woven fabric according to claim 8, wherein the graft ratio is 50% or more and 300% or less.

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