JP2015504015A - Flame retardant and moisture resistant nonwoven panel and construction method thereof - Google Patents

Abstract

  A flame-retardant and moisture-resistant nonwoven panel and a method for constructing the same are provided. The panel includes a bonded nonwoven sheet of bast fibers combined with polymeric binding fibers. In addition, the panel includes a single layer coating of the dried and cured solution. The dried and cured coating includes a binder, a Ph stabilizer and one flame retardant. The binder is crosslinked with the bast fibers to form a moisture resistant barrier that reduces the moisture absorption of the bast fibers.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a benefit of US Provisional Application Serial No. 61 / 569,975, filed December 13, 2011, and US Provisional Application Serial Number, filed September 20, 2012. No. 61 / 703,613, all of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION TECHNICAL FIELD This invention relates generally to nonwoven panels, and more particularly to flame retardant and moisture resistant nonwoven structural panels and methods for their construction.

2. Related Art It is known to construct a structural panel, that is, one that can function as a structural member such as an office partition panel, from a glass fiber composite by bonding glass fiber and resin. However, the resin used to construct the glass fiber panel contains a high level of formaldehyde that can be harmful to humans, and the new rule CAL 1350 requires that the level of formaldehyde be less than 0.04 ppm. Not allowed. In addition, glass fiber panels are not environmentally friendly because they have a relatively high carbon footprint during manufacturing and are typically made of non-renewable materials.

  In addition to glass fiber panels, it is known to construct panels containing natural fibers combined with resin. However, the known composition of these panels tends to absorb moisture and can have an adverse effect on their structural capacity. Thus, natural fiber panels typically do not meet the humidity, impact and board stiffness tests required for office partitionable board applications. In addition, these panels are typically constructed by expensive processes including, for example, requiring multiple coating processes. Therefore, their expensive construction typically makes them cost-effective and therefore is excluded from use in many applications. Furthermore, natural fiber based boards typically have a brown color and are undesirable for conspicuous office panel applications.

SUMMARY OF THE INVENTION According to one aspect of the invention, a flame retardant and moisture resistant nonwoven panel is provided. The panel includes a bonded nonwoven sheet of bast fibers combined with polymeric binding fibers. In addition, the panel includes a single layer coating of the dried and cured solution. The dried and cured coating includes a binder, a Ph stabilizer and one flame retardant. The binder is crosslinked with the bast fibers to form a moisture resistant barrier that reduces the moisture absorption of the bast fibers.

  According to another aspect of the invention, the panel meets the requirements of Regulation CAL 1350 which requires that the formaldehyde level be less than 0.04 ppm.

  According to another aspect of the invention, the panel is formed as an office divider panel that passes the ASTM E-84 flammability test.

  According to another aspect of the invention, the mixture comprises between 50-80% by weight bast fibers and between 15-50% by weight polymer-bonded fibers.

  According to another aspect of the invention, the bonded nonwoven fabric is between 150 gsm and 1500 gsm.

  According to another aspect of the invention, the dried and cured coating has a dry pick-up weight between 30 gsm and 300 gsm.

  According to another aspect of the invention, a formaldehyde-free scrim layer is bonded to at least one side of the panel.

  According to another aspect of the invention, a method of constructing a flame retardant and moisture resistant nonwoven panel is provided. The method comprises the steps of forming a homogeneous compound of bast fibers and polymer bonded fibers, forming a woven fabric of a homogeneous mixture, melting the polymer bonded fibers, and forming the materials of the bast fibers and the polymer bonded fibers. Bonding to form a bonded nonwoven sheet; saturating the bonded nonwoven sheet in a solution comprising a binder, a Ph stabilizer and a flame retardant; and drying the saturated bonded nonwoven sheet; Cross-linking the binder and bast fibers by curing the solution and compressing the nonwoven sheet.

  According to another aspect of the invention, the method includes maintaining the formaldehyde level in the panel below 0.04 ppm.

  According to another aspect of the invention, the method includes compressing the nonwoven sheet while curing the solution.

  According to another aspect of the invention, the method includes cooling the nonwoven sheet while the nonwoven sheet is compressed.

  According to another aspect of the invention, the method includes the step of using, for the binder, a polycarboxylic acid modified with a polyol.

  According to another aspect of the invention, the method includes providing the flame retardant as one flame retardant.

  According to another aspect of the invention, the method includes bonding a formaldehyde-free scrim layer to at least one side of the panel.

  These and other aspects, features and advantages of the present invention will be more readily understood when considered in conjunction with the following detailed description of the preferred embodiment and the best mode of the invention, the appended claims and the accompanying drawings. Will be done.

4 is a process flowchart illustrating steps for building a panel according to one aspect of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring more particularly to the drawings, FIG. 1 is a flame retardant and moisture resistant nonwoven panel, hereinafter referred to as panels 10, 10 ', 10 ", constructed in accordance with the invention. And a method of constructing panels 10, 10 ', 10 "according to another aspect of the invention. Panel 10, 10 ', 10 "includes a bonded nonwoven sheet 12 and a dried and cured coating 14 (FIG. 2) formed from one solution 16. Solution 16 is a single process. Drying and curing minimizes space requirements and process steps during manufacture.Sheet 12 is made up of high-strength bast fibers 18 and high bonds with each other by a process that at least partially melts the polymer binding fibers 20. Formed from a mixture with molecular binding fibers 20. Solution 16 includes a solution-based binder, a Ph stabilizer and one flame retardant, which binds to bast fibers 18 and is impervious. Or forms a substantially impervious moisture resistant barrier, which greatly reduces the tendency to absorb moisture in the bast fibers 18. Thus, the bast fibers 18 and parts thereof Panel 10, 10 'is constructed, the structural integrity of the 10 "is maintained during even used in the presence of moisture. This allows panels 10, 10 ', 10 "to meet the stringent requirements of office partitionable boards according to ASTM E-84 classification A, and pass humidity, impact and board stiffness tests. Therefore, since the panels 10, 10 ', and 10 "have high strength and high rigidity, they are suitable for use as a structural member such as an office partition panel. Furthermore, the panels 10, 10 ', 10 "are recoverable, recyclable, mostly natural and biodegradable, the materials used to construct the panels 10, 10', 10" In addition, panels 10, 10 ', 10 "are designated as office divider boards because they are environmentally friendly in that they contain formaldehyde levels below 0.04 ppm, hereinafter referred to as" very low levels of formaldehyde ". Suitable for use in applications where it is necessary to pass Regulation CAL 1350, which requires that the formaldehyde content in it contain less than 0.04 ppm formaldehyde.

  The bast fibers 18 are exemplary and can be provided from a variety of natural fibers such as, but not limited to, jute, kenaf, hemp, flax or mixtures thereof. The bast fibers 18 are typically provided to have a content between about 50-85% by weight, and in one example are provided as 80% by weight kenaf.

  Polymer bonded fibers 20 are exemplary and include, but are not limited to, polypropylene, polyethylene, copolyesters, nylons, polyactic acid (PLA), and composite fibers (sheaths typically have a low melt height). It is a molecular material and the core can be provided from a variety of thermally bondable materials including sheath / core fibers that are high temperature polymeric materials. The polymer bonded fiber 20 is generally provided to have a content between 15 and 50% by weight, and in one example is provided as a 20% by weight composite fiber including a polyester core and a modified polyester sheath. .

  In one example, the solution-based binder is provided as a polycarboxylic acid modified with a polyol diluted with water. The polyol is mainly used as a cross-linking agent, while the modified polycarboxylic acid is compatible with the natural fiber of the bast fiber 18 and provides good cross-linking between the natural fiber and the molten resin of the polymer bonded fiber 20. Forming facilitates the formation of an impermeable or substantially impermeable barrier, which greatly reduces the tendency of the bast fibers 18 to absorb moisture. It is important that the binder be a solution system. This is because conventional dispersion-based latex binders are known to burn under the ASTM E-84 test method and therefore do not meet the requirements of a Class A rating. The binder content can range between 10-20% by weight, and in one example, a binder content of 14% by weight is used.

  The flame retardant is provided as a single flame retardant and is applied in a single process to minimize the complexity and cost of the manufacturing process. For example, the flame retardant can be provided as a boron-based component, a phosphorus-based component, or a sulfur-based component. Since polycarboxylic acids have low Ph, Ph stabilizers are used to mix flame retardants in the binder. The flame retardant used in one example is exemplary and is, but not limited to, disodium octaborate tetrahydrate. The flame retardant content can be provided between about 5-25% by weight, and in one example, a content of 15% by weight is used for a 30% by weight dry pickup from chemical solids.

  The process of constructing the panel 10 includes forming a homogenous mixture of bast fibers 18 and polymer binding fibers 20, generally shown at 22, forming a fabric 24 of the homogeneous mixture 22, and heating the fabric 24. The polymer binding fiber 20 is at least partially melted to bond the bast fiber 18 with the molten material of the polymer binding fiber 20 to form the bonded nonwoven sheet 12, and the binder, Ph stabilizer and Providing a solution 16 containing a flame retardant; saturating the bonded nonwoven sheet 12 with the solution 16; and drying the saturated bonded nonwoven sheet 12 to bond the binder and bast fibers 18 in the solution 16; And curing the solution and compressing the nonwoven sheet 12, and the method further provides improved stiffness and color change from natural fiber color. If negligence may optionally include the step of bringing into association the scrim layer 25 containing no formaldehyde least one side of the sheet 12 (panel 10 ') or both (panel 10 ").

  More specifically, the process includes the steps of mixing bast fibers 18 and polymer binding fibers 20 with a mixer until the mixture 22 is homogeneous, and then mixing with a fine opener. The homogeneity provides a uniform distribution of the polymer bonded fibers 20, but it is required to obtain maximum and uniform stiffness throughout the finish panel 10.

  Thereafter, in forming a homogenous mixture 22 of bast fibers 18 and polymeric binding fibers 20, the mixture 22 is processed on a fabric forming machine to produce a nonwoven fabric 24. The weight of the fabric 24 can vary from about 150 gsm (grams per square meter) to about 1500 gsm, with the sample weight being formed per 700 gsm.

  Thereafter, in forming the fabric 24, the fabric 24 is heated to a temperature suitable to melt at least a portion of the polymer bonded fiber 20, such as in a furnace generally identified at 26, thereby providing a bast. The fibers 18 and the polymer bonded fibers 20 are bonded together to form the bonded nonwoven sheet 12.

  Thereafter, the bonded nonwoven sheet 12 is saturated with the solution 16, such as by passing through a bath of solution 16 identified generally at 28. Solution 16 is a solution-based binder having a low Ph, a Ph stabilizer that compensates for the low Ph of the binder, and, as explained above, when not used as a Ph stabilizer, it is difficult to be further diluted with water. Including flame retardants. The amount of saturation is done to provide about 10-40% dry pickup of solution 16, and the total binder pickup in one example is about 30% dry pickup, and the total disodium octaborate tetrahydrate. The pickup is between about 5 and 25% by weight relative to a 30% dry pickup from chemical solids.

  Thereafter, the saturated bonded nonwoven sheet 12 is illustrative and not limited to heating sufficiently to dry the sheet 12 and cure the solution 16, such as in a continuous compression belt furnace 30. During the drying and curing heating process, the water from solution 16 is first substantially evaporated leaving a moisture content of about 8-10% in the bonded nonwoven sheet 12. Thereafter, in achieving the desired moisture content, the temperature is raised to about 180-200 degrees Celsius, at which temperature the binder of solution 16 cures and crosslinks with the bast fibers 18. While the binder is cured, the bonding sheet 12 is compressed to a predetermined finish thickness under force F, such as, but not limited to, a pair of high compression belts 32. Further, while still compressed between belts 32 and when fully cured, the resulting panel 10 is cooled, and heating, compression and cooling are all performed in a continuous compression belt furnace 30. Can do.

  A cooled and compressed panel 10 is illustrative when there is a need to meet the requirements of the intended application, and includes, but is not limited to, a scrim laminator that includes at least one formaldehyde-free scrim layer 25 such as glass fiber or polypropylene. 34 can then be further processed by laminating on one or both sides of each panel 10 ', 10 "by 34. The finished panels 10, 10', 10" obtained are in accordance with ASTM E-84. The panel 10 ', 10 "is further improved in the presence of moisture due to the synergistic effect obtained by the solution-based binder, the binding fiber 20, and the scrim layer 25. Of high board rigidity and a very low formaldehyde content. When considered in applications unnecessary, the panel 10 can remain free scrim layer 25. In this case, panel 10 ', the panel 10 having reduced strength compared with the 10 "is obtained. Throughout the process, the sheet 12 remains a single continuous material from the start of the process until after compression, curing and cooling, or in the case of the laminated scrim layer 25, after lamination. The desired length of panel 10, 10 ', 10 "can be cut by cutting operation 36. When cutting operation 36 is performed, it is shown to be after compression and after lamination.

Many modifications and variations of the present invention are possible in light of the above teachings. Accordingly, it will be understood that the invention may be practiced otherwise than as specifically described, and the scope of the invention be defined by any finally allowed claim.

Claims (29)

A flame retardant and moisture resistant nonwoven panel, the nonwoven panel comprising:
A bonded nonwoven sheet, the bonded nonwoven sheet comprising a mixture of bast fibers bonded with polymeric bonded fibers, the nonwoven panel further comprising:
Comprising a single layer coating of the dried and cured solution, the solution comprising a binder, a Ph stabilizer and one flame retardant, wherein the binder is cross-linked with the bast fiber, Nonwoven panels that form moisture barriers that reduce moisture absorption.   The flame retardant and moisture resistant nonwoven panel of claim 1 further comprising a scrim layer bonded to at least one side of the panel.   The flame retardant and moisture resistant nonwoven panel of claim 2, wherein the scrim layer does not contain formaldehyde.   The flame retardant and moisture resistant nonwoven panel of claim 3, further comprising the scrim layer bonded to both sides of the panel.   The flame retardant and moisture resistant nonwoven of claim 1, wherein the mixture comprises between 50 and 80 wt% of the bast fibers and between 15 and 50 wt% of the polymer bonded fibers. panel.   The flame retardant and moisture resistant nonwoven panel of claim 1, wherein the bonded nonwoven sheet is between 150 gsm and 1500 gsm.   The flame retardant and moisture resistant nonwoven panel of claim 1, wherein the dried and cured coating has a dry pickup weight of between 30 and 300 gsm.   The flame retardant and moisture resistant nonwoven panel of claim 1, wherein the panel contains less than 0.04 ppm formaldehyde.   The flame retardant and moisture resistant nonwoven panel according to claim 1, wherein the flame retardant is provided from at least one of the group consisting of a boron compound, a phosphorus compound, and a sulfur compound.   The flame retardant and moisture resistant nonwoven panel according to claim 9, wherein the flame retardant is provided as disodium octaborate tetrahydrate.   The flame retardant and moisture resistant nonwoven panel of claim 9, wherein the flame retardant is provided to have between about 5 and 25 wt%.   The flame retardant and moisture resistant nonwoven panel of claim 11, wherein the flame retardant is provided to have about 15 wt%.   The flame retardant and moisture resistant nonwoven panel according to claim 1, wherein the panel is an office partition panel.   The flame retardant and moisture resistant nonwoven panel of claim 1, wherein the panel meets the requirements of an ASTM E-84 Class A office divider affixable board. Forming a homogeneous compound of bast fibers and polymer binding fibers;
Forming a fabric of the homogeneous mixture;
Melting the polymer-bonded fibers and bonding the bast fibers and the material of the polymer-bonded fibers to form a bonded nonwoven sheet;
Saturating the bonded nonwoven sheet in a solution comprising a binder, a Ph stabilizer and a flame retardant;
Crosslinking the binder and the bast fibers by drying the saturated bonded nonwoven sheet and curing the solution;
Compressing the nonwoven sheet, and building a flame retardant and moisture resistant nonwoven panel.   The method of claim 15, further comprising compressing the nonwoven sheet while curing the solution.   The method of claim 16, further comprising cooling the nonwoven sheet while compressing the nonwoven sheet.   16. The method of claim 15, further comprising using a polycarboxylic acid modified with a polyol for the binder.   16. The method of claim 15, further comprising the step of forming the solution by diluting the binder with water and blending one flame retardant with a mixture of the binder and water.   16. The method of claim 15, further comprising using about 10-20% by weight of the binder in the solution.   The method of claim 15, further comprising laminating a scrim layer on at least one side of the panel.   The method of claim 21, further comprising providing the scrim layer free of formaldehyde.   The method of claim 15, further comprising constructing the panel to have a formaldehyde content of less than 0.04 ppm.   The method according to claim 15, further comprising providing the flame retardant from at least one of the group consisting of a boron compound, a phosphorus compound, and a sulfur compound.   25. The method of claim 24, further comprising providing the flame retardant as disodium octaborate tetrahydrate.   26. The method of claim 25, further comprising providing the flame retardant to have about 15% by weight.   25. The method of claim 24, further comprising providing the flame retardant to have between about 5-25% by weight.   16. The method of claim 15, further comprising the step of constructing a flame retardant and moisture resistant nonwoven panel to meet the requirements of ASTM E-84 Class A office divider affixable board.   16. The method of claim 15, further comprising maintaining the nonwoven sheet as a single continuous material until the sheet is compressed and then the sheet is cut to form the panel of the desired length. The method described.

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