WO2020219275A1

WO2020219275A1 - Waterproof and breathable composite nanofiber membrane and methods of manufacture

Info

Publication number: WO2020219275A1
Application number: PCT/US2020/027513
Authority: WO
Inventors: Lei Li; Yatinkumar N. Rane; Kaiyi Liu; Thomas D. Carr; Yit-Hong Tee; Vishal Bansal; Leonard R. Castellano; Yogesh NER
Original assignee: Parker-Hannifin Corporation
Priority date: 2019-04-22
Filing date: 2020-04-09
Publication date: 2020-10-29
Also published as: TW202104529A

Abstract

A waterproof and breathable membrane and methods of manufacturing the membrane are provided. The membrane includes a nanofiber web of polymer fibers coated with a hydrophobic material. The hydrophobic material coated nanofiber web has a fiber size of between 1 nm and 1000 nm, a basis weight of 5-40 gsm, a hydrostatic head of at least 10,000 mm of water, an air permeability of at least 1.0 cfm, a mean flow pore size of greater than 0.2 um and less than 5 um and a bubble point pore size of greater than 0.5 um and less than 10 um, and a moisture vapor transmission rate of at least 1000 g/24hr/m2. These parameters provide good hydrophobic and oleophobic characteristics while maintaining breathability. The hydrophobic material coating may be applied by way of plasma coating a fluorinated monomer onto the nanofiber web.

Description

WATERPROOF AND BREATHABLE COMPOSITE NANOFIBER MEMBRANE AND METHODS OF MANUFACTURE

FIELD OF THE INVENTION

[0001] The present invention relates to waterproof and breathable membranes and methods of making same.

BACKGROUND OF THE INVENTION

[0002] It is desired to provide membranes that are both breathable and waterproof. The desire is to provide a membrane that can be used to impart water resistance to garments, without impeding breathability. Such a microporous membrane would be particularly useful in outdoor products such as outdoor clothing, temporary tent shelters, backpacks and other similar permeable products that benefit from water resistance while maintaining breathability.

[0003] Usually, a laminate made from a nanofiber membrane that would impart water resistance to these types of products, would also impede breathability.

[0004] Attempts to provide water resistance to nanofiber membranes have used a dip- and-nip method where a nanofiber web is formed and then passed through a bath of a water repellant coating. After passing through the bath, excess coating is removed by passing the coated nanofiber web through a nip of rollers. Unfortunately, this process undesirably blocks or reduces the size of the pores in the nanofiber web adversely affecting the breathability of the resulting membrane. Other methods such as using binders and extenders similarly adversely affect other performance characteristics.

[0005] Prior art includes WO2017028656 Al, US20090123713 Al, W02009064841 Al, EP2212106 Al, EP2212106 Bl, US20090123700 Al, US8241729 B2,

W02009064311 Al, CN101854820 A, CN101854820 B, and IN2010DN03641. Also, US8231378B2, S20140035177A1, US20180215130 Al, US20180371687A1,

JP4518087B2, KR101106679B1, WO2017028656A1, US20090123713 Al, and

US8241729 B2. BRIEF SUMMARY OF THE INVENTION

[0006] Embodiments of the present application provide new and improved membranes and more particularly new and improved membranes that provide breathability and water resistance.

[0007] In an embodiment, a waterproof and breathable material is provided. The material includes a nanofiber web of polymer fibers coated with a hydrophobic material such as possibly a fluorinated polymer having a fiber size of between 1 nm and 1000 nm, a basis weight of 5-40 gsm, a hydrostatic head of at least 10,000 mm of water, an air permeability of at least 1.0 cfm, a mean flow pore size of greater than 0.2 nm and less than 5 um and a bubble point pore size of greater than 0.5 um and less than 10 um, and a moisture vapor transmission rate of at least 1000 g/24hr/m².

[0008] In one embodiment, the hydrophobic material is a fluorinated polymer.

[0009] In one embodiment, the hydrophobic material coated nanofiber web has a water contact angle of at least 115 degrees after the hydrophobic material coating is applied to the nanofiber web and the nanofiber web without the hydrophobic material has a contact angle less than 115 degrees.

[0010] In another embodiment, the nanofiber web is hydrophilic without the hydrophobic material, e.g. Nylon 6.

[0011] In one embodiment, the polymer fibers are formed from at least one of polyacetals, polyamides, polyurethanes, epoxy, polyesters, cellulose ethers, cellulose esters, polyalkylene sulfides, polyarylene oxides, polysulfones, modified polysulfone polymers and mixtures thereof, poly(vinylchloride), polymethylmethacrylate, polystyrene, and copolymers thereof, poly(vinylidene fluoride), poly(vinylidene chloride), polyvinylalcohol.

[0012] In one embodiment, the fibers of the nanofiber web are formed by forcespinning and not from electrospinning. [0013] In one embodiment, the nanofiber web without the hydrophobic material is hydrophobic.

[0014] In one embodiment, the hydrostatic head is measured per AATCC 127, the air permeability is measured per ASTM D737, and the moisture vapor transmission rate is measured per ASTM E96.

[0015] In one embodiment, the hydrophobic material is a fluorinated polymer coating that is applied to the nanofiber web by plasma coating a fluorinated monomer to form a fluorinated polymer coating.

[0016] In one embodiment, the hydrophobic material is not applied to the nanofiber web by dipping the nanofiber web in a bath of the coating and then passing the nanofiber web and hydrophobic material combination through a nip formed between a pair of squeeze rolls.

[0017] In one embodiment, the hydrophobic material coated nanofiber web is oleophobic.

[0018] In one embodiment, the hydrophobic material coated nanofiber web has an oil rating of 6 as per AATCC 118.

[0019] In one embodiment, the hydrophobic material coating does not use a binder or extender.

[0020] In one embodiment, a method of forming a waterproof and breathable material is provided. The method includes forming a nanofiber web of polymer fibers. The method includes coating the nanofiber web with a hydrophobic material to form a hydrophobic material coated nanofiber web. The hydrophobic material coated nanofiber web having a fiber size of between 1 nm and 1000 nm, a basis weight of 5-40 gsm, a hydrostatic head of at least 10,000 mm of water, an air permeability of at least 1.0 cfm, a mean flow pore size of greater than 0.2 nm and less than 5 nm and a bubble point pore size of greater than 0.5 um and less than 10 um, and a moisture vapor transmission rate of at least 1000 g/24hr/m². [0021] In one embodiment, the step of coating the nanofiber web is performed by plasma coating the fluorinated polymer to the nanofiber web.

[0022] In one embodiment, the step of coating does not include dipping the nanofiber web in the hydrophobic material.

[0023] In one embodiment, the step of coating does not further include passing the nanofiber web and hydrophobic material combination through a nip formed between a pair of squeeze rolls.

[0024] In one embodiment, plasma coating the fluorinated polymer includes using a fluorinated monomer to form the fluorinated polymer coating.

[0025] In one embodiment, the coated nanofiber web has a bubble point pore size of greater than 1 um.

[0026] In one embodiment, the step of coating the nanofiber web does not use a binder or an extender to coat the nanofiber web with the hydrophobic material.

[0027] In one embodiment, the step of forming a nanofiber web is performed by forecespinning.

[0028] In one embodiment, forcespinning does not include electrospinning.

[0029] In one embodiment, the method includes securing the coated nanofiber web to a fabric layer to form a laminate.

[0030] In another embodiment, a waterproof and breathable material formed by the methods outlined above.

[0031] In another embodiment, a product includes a laminate including a membrane layer formed by the membrane as described above secured to another layer.

[0032] In one embodiment, the product is an article of clothing. [0033] In one embodiment, the additional layer forms a layer that is positioned outward relative to the membrane.

[0034] Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0036] FIG. 1 is a simplified illustration of system for forming a microporous membrane according to the present application; and

[0037] FIG. 2 is an image of a microporous membrane according to an embodiment of the application.

[0038] While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

[0039] Embodiments of the application relate to microporous membranes that provide both water resistance and breathability. Particularly, the microporous membranes may comprise nanofibers. The nanofibers may be spun in a random non-woven orientation having an effective pore structure and hydrophobic surface coating for air and water vapor passage and restricted liquid water passage. The microporous membrane may then be used as part of a laminate to impart the water resistance and breathability characteristics to the clothing, shelter, backpack or other product manufactured from the laminate. [0040] In some implementations, after the nanofibers are spun to form a nanofiber web, the nanofiber web is coated with a material and preferably a hydrophobic material such that the resulting membrane will exhibit hydrophobic and oleophobic characteristics. In a preferred implementation, the hydrophobic material is a fluorinated polymer. Preferably, the nanofibers are forcespun and not eletrospun. However, some methods of manufacturing may use electrospinning or other methods to produce the nanofiber web.

[0041] FIG. 1 illustrates a simplified system 100 for forming the microporous membrane. The system includes a solution feed system 102 for feeding the solution from which the nanofibers are formed, typically a polymer solution, towards a spinneret 106 where the nanofibers will be forcespun. In some implementations, the forcespinning process does not include electrospinning. However, in other implementations other types of spinning may be used to form the nanofibers used to form nanofiber web 130.

[0042] The solution feed system 102 includes a solution supply system 108, which may be a container holding the first solution. A pump 110 directly pumps solution towards the spinneret 106 forming a flow of the first solution through piping 111 to spinneret 106.

[0043] In preferred implementations, the spinneret 106 rotates at an excess of 2500 RPM and dispenses the mixture to form nanofiber layer 130 from the polymer. In some embodiments, the nanofiber web 130 is formed on a substrate 132, e.g. the non-woven fibers from the spinneret 106 are accumulated in a random, non-woven orientation on the substrate 132 to form nanofiber web 130.

[0044] The nanofiber web 130 is then subjected to post forming processing. For example, the fibers of the nanofiber web 130 may be coated with a hydrophobic material.

In a preferred implementation, the hydrophobic material is a fluorinated polymer. In FIG.

1, the nanofiber web 130 passes through a coating system 134 to coat the nano-fiber web with the hydrophobic coating. In one system, the coating system may be a fluorination system that uses plasma fluorination to coat the nano-fiber web with the fluorinated polymer. [0045] In a particular implementation, a fluorinated monomer chemical is polymerized onto the nanofiber surface resulting in a fluorinated polymer coating. Chemicals such as NANOFICS® 110, and NANOFICS® 120, or a halogen free reagent such as

PLASMAGUARD produced by Europlasma of Oudenaarde, Belgim may be used for the plasma coating process.

[0046] FIG. 2 is a photograph of an example of a microporous membrane formed using the present application.

[0047] Before plasma coating, the nanofiber web may be either hydrophobic or hydrophilic. The plasma coating process improves the hydrophobic and oleophobic characteristics of the resulting membrane.

[0048] In preferred embodiments, after coating, the resulting microporous membrane will have an average fiber size of between 1 nm to 1000 nm, a basis weight of between 5 and 40 gsm, and a hydrostatic head of at least 10,000 mm of water (as per AATCC 127). After coating, the microporous membrane preferably has an air permeability of at least 1.0 cfm (as per ASTM D737).

[0049] After plasma coating, the microporous membrane preferably has a mean flow pore size of greater than 0.2 um and less than 5 um, and more preferably between 0.5 um and 1.5um. After coating, the microporous membrane preferably has an average bubble point pore size of greater than 0.5 um and less than 10 um, and more preferably between 1 um and 3 um.

[0050] After coating, the microporous membrane preferably has a moisture vapor transmission rate (MVTR) of at least 1000 g/24hr/m² (per ASTM E96). In some embodiments, the MVTR may be in excess of 45,000 g/24hr/m² and in some embodiments, the MVTR may be in approximately 60,000 g/24hr/m² or more.

[0051] In some embodiments, the minimum fiber diameter may be greater than 50 nm, more particularly greater than 75 nm, more particularly greater than 100 nm, more particularly, greater than 125 nm, and even more particularly greater than 150 nm. [0052] In some embodiments, the maximum fiber diameter may be less than 1000 nm, more particularly less than 950 nm, more particularly less than 900 nm, more particularly, less than 600 nm, and even more particularly less than 500 nm.

[0053] After coating, the membrane exhibits hydrophobic and oleophobic properties. In preferred membranes, the hydrophobic characteristic is illustrated by way of a water contact angle of at least 115 degrees measured by way of goniometer using de-ionized water. In preferred membranes, the oleophobic properties is illustrated by way of an oil rating of 6 or better as per AATCC 118.

[0054] In some embodiments, the water contact angle may be less than 145 degrees while still providing the desired moisture vapor transmission rate and air permeability parameters.

[0055] In some embodiments, the nanofiber web showed a contact angle of 0 degrees without the hydrophobic coating.

[0056] The following chart is some representative samples of microporous membranes according to embodiments of the application.

EXAMPLES

1. Frazier air permeability may be measured per ASTM D737

2. Hydrostatic head (HSH) may be measured per AATCC 127

3. Moisture vapor transmission rate may be measured per ASTM E96

[0057] As noted above, the fibers of the nanofiber web are coated with hydrophobic material to exhibit hydrophobic and oleophobic characteristics. [0058] The polymer fibers may be formed from, but are not limited to, polyacetals, polyamides, polyurethanes, epoxy, polyesters, cellulose ethers, cellulose esters, polyalkylene sulfides, polyarylene oxides, polysulfones, modified polysulfone polymers and mixtures thereof, poly(vinylchloride), polymethylmethacrylate, polystyrene, and copolymers thereof, poly(vinylidene fluoride), poly(vinylidene chloride), polyvinylalcohol.

[0059] Solvents used for the nanofiber production process may be anyone of the following, but not limited to: formic acid and water, ethanol, chloroform, acetone, N,N- Di- methylformamide (DMF), dimethylacetamide (DMAc), formic acid, acetic acid, N-Methyl- 2-pyrrolidone (NMP), tetrahydrofuran (THF) and mixture thereof.

[0060] Further, test samples were prepared according to the present application. These samples had the following characteristics:

[0061] It is noted that the present method of forming the waterproof and breathable membrane does not expose the nanofiber web to the dip-and-nip method of applying water repellant coatings to the nanofiber web. Instead, a plasma coating method is used. This method avoids the problems of the dip-and-nip method related to blocking the pores of the membrane which adversely affects the breathability of the resulting membrane. Further, the plasma coating method is contemplated to use less coating material.

[0062] In alternative methods, coatings incorporate binders or extends. However, while some performance characteristics may be improved, other performance characteristics may be hampered due to the presence of the binders and extends. These detriments are not exhibited using the instant methods that avoid using binders or extenders such that improved performance characteristics are exhibited. [0063] Such microporous membranes as described above can be used in various applications including waterproof apparel as well as non-apparel.

[0064] Once formed, the microporous membrane can be bonded to an outer fabric layer by means selected from stitching, adhesive bonding, thermal bonding, ultrasonic bonding and combinations thereof, resulting in a waterproof and breathable material.

[0065] Typically, outer fabric layers may include a layer of face fabric facing outward of the apparel and/or a layer of backer fabric facing inward and closer to the skin than the microporous membrane and the face fabric.

[0066] All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0067] The use of the terms“a” and“an” and“the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms“comprising,”“having,”“including,” and “containing” are to be construed as open-ended terms (i.e., meaning“including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g.,“such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non- claimed element as essential to the practice of the invention. [0068] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

WHAT IS CLAIMED IS:

1. A waterproof and breathable material, comprising:

a nanofiber web of polymer fibers coated with a hydrophobic material having a fiber size of between 1 nm and 1000 nm, a basis weight of 5-40 gsm, a hydrostatic head of at least 10,000 mm of water, an air permeability of at least 1.0 cfm, a mean flow pore size of greater than 0.2 nm and less than 5 nm and a bubble point pore size of greater than 0.5 um and less than 10 um, and a moisture vapor transmission rate of at least 1000 g/24hr/m².

2. The material of claim 1, wherein the hydrophobic material is a fluorinated polymer such that the coated nanofiber web is hydrophobic.

3. The material of claim 1, wherein the hydrophobic material coated nanofiber web has a water contact angle of at least 115 degrees after the hydrophobic material coating is applied to the nanofiber web and the nanofiber web without the hydrophobic material coating has a contact angle less than 115 degrees.

4. The material of claim 1, wherein the polymer fibers are formed from at least one of polyacetals, polyamides, polyurethanes, epoxy, polyesters, cellulose ethers, cellulose esters, polyalkylene sulfides, polyarylene oxides, polysulfones, modified polysulfone polymers and mixtures thereof, poly(vinylchloride), polymethylmethacrylate, polystyrene, and copolymers thereof, poly(vinylidene fluoride), poly(vinylidene chloride),

polyvinylalcohol.

5. The material of claim 1, wherein the fibers of the nanofiber web are formed by forcespinning and not from electrospinning.

6. The material of claim 1, wherein the nanofiber web without the hydrophobic coating is hydrophilic or hydrophobic.

7. The material of claim 1, wherein the hydrostatic head is measured per AATCC 127, the air permeability is measured per ASTM D737, and the moisture vapor transmission rate is measured per ASTM E96.

8. The material of claim 2, wherein the fluorinated polymer coating is applied to the nanofiber web by plasma coating a fluorinated monomer to form a fluorinated polymer coating.

9. The material of claim 1, wherein the hydrophobic material is not applied to the nanofiber web by dipping the nanofiber web in a bath of the hydrophobic material and then passing the nanofiber web and hydrophobic material combination through a nip formed between a pair of squeeze rolls.

10. The material of claim 2, wherein the hydrophobic material coated nanofiber web is oleophobic.

11. The material of claim 1, wherein the hydrophobic material coated nanofiber web has an oil rating of 6 as per AATCC 118.

12. The material of claim 1, wherein the hydrophobic material coating does not use a binder or extender.

13. The material of claim 1, wherein the hydrophobic material coating is a halogen free material.

14. A method of forming a waterproof and breathable material, comprising: forming a nanofiber web of polymer fibers, coating the nanofiber web with a hydrophobic material to form a hydrophobic material coated nanofiber web, the hydrophobic material coated nanofiber web having a fiber size of between 1 nm and 1000 nm, a basis weight of 5-40 gsm, a hydrostatic head of at least 10,000 mm of water, an air permeability of at least 1.0 cfm, a mean flow pore size of greater than 0.2 nm and less than 5 nm and a bubble point pore size of greater than 0.5 um and less than 10 um, and a moisture vapor transmission rate of at least 1000 g/24hr/m².

15. The method of claim 14, wherein the step of coating the nanofiber web is performed by plasma coating a fluorinated polymer to the nanofiber web.

16. The method of claim 14, wherein the step of coating does not include dipping the nanofiber web in the hydrophobic material.

17. The method of claim 16, wherein the step of coating does not include passing the hydrophobic material coated nanofiber web through a nip formed between a pair of squeeze rolls.

18. The method of claim 15, wherein plasma coating the fluorinated polymer includes using a fluorinated monomer to form the fluorinated polymer coating.

19. The method of claim 14, wherein the coated nanofiber web has a bubble point pore size of greater than 1 um.

20. The method of claim 14, wherein the step of coating the nanofiber web does not use a binder or an extender to coat the nanofiber web with the hydrophobic material.

21. The method of claim 14, wherein the step of forming a nanofiber web is performed by forecespinning.

22. The method of claim 21, wherein forcespinning does not include electrospinning.

23 The method of claim 14, further comprising securing the coated nanofiber web to a fabric layer to form a laminate.

24. The method of claim 13, wherein the hydrophobic material is a halogen free material.

25. A waterproof and breathable material formed by the process of any one of claims 14-24.

26. A product comprising:

a laminate including a membrane layer formed by the membrane of anyone of claims 1-13 secured to another layer.

27. The product of claim 26, wherein the product is an article of clothing.