BREATHABLE COATED FABRIC
A water vapor-permeable, air-impermeable and water-impermeable sheet material comprises a film bonded to a fibrous substrate. The film comprises a reaction extrusion-processed blend comprising a first block copolymer which comprises a polyether block amide copolymer and a second block copolymer which comprises a copolyether ester. The fibrous substrate may be woven or non-woven, and may comprise polyethylene, polypropylene, polyethylene terephthalate, a polyamide, glass mat, felt, paper, or combinations thereof. The water vapor transmission rate of the extruded film is substantially higher than that of a film made from either one of the component block copolymers. The sheet material has uses which include housewrap, roofing underlayment, breathable apparel, desiccant packaging and others.
1 . A water vapor-permeable sheet material comprising:
(a) a film comprising a reaction extrusion-processed blend comprising a first block copolymer which comprises a polyether block amide copolymer and a second block copolymer which comprises a copolyether ester; and
(b) a fibrous substrate bonded to the film.
2 . A material according to claim 1 , wherein the first block copolymer comprises polyamide blocks and polyether blocks.
3 . A material according to claim 2 , wherein the polyamide block comprises polyamide 6, 11 or 12.
4 . A material according to claim 2 , wherein the polyether block comprises a polyalkylene glycol.
5 . A material according to claim 2 , wherein the polyether block comprises polyethylene glycol, polypropylene glycol or polytetramethylene glycol.
6 . A material according to claim 1 , wherein the first block copolymer is the product of polycondensation of a carboxylic acid polyamide with an alcohol termination polyether.
7 . A material according to claim 1 , wherein the first block copolymer is Pebax.
8 . A material according to claim 1 , wherein the second block copolymer comprises polyether blocks and polyester blocks.
9 . A material according to claim 8 , wherein the polyether blocks of the second block copolymer comprise a poly (alkylene oxide).
10 . A material according to claim 9 , wherein the poly (alkylene oxide) comprises polyethylene glycol, polypropylene glycol or polytetramethylene glycol.
11 . A material according to claim 8 , wherein the polyester blocks comprise a poly (alkylene terephthalate).
12 . A material according to claim 11 , wherein the poly (alkylene terephthalate) comprises polybutylene terephthalate or polyethylene terephthalate.
13 . A material according to claim 1 , wherein the second block copolymer comprises Arnitel.
14 . A material according to claim 1 , wherein the blend further comprises a compatibilizer.
15 . A material according to claim 14 , wherein the compatibilizer comprises a polymer functionalized by maleic anhydride grafting.
16 . A material according to claim 14 , wherein the compatibilizer comprises ethylene methyl acrylate copolymer or ethylene vinyl acetate.
17 . A material according to claim 1 , wherein the blend further comprises a colorant or a UV-inhibitor, or both.
18 . A material according to claim 1 , wherein the substrate is woven.
19 . A material according to claim 18 , wherein the substrate comprises polyethylene, polypropylene, polyethylene terephthalate, a polyamide, glass mat, felt, paper, or combinations thereof.
20 . A material according claim 1 , wherein the substrate is non-woven.
21 . A material according to claim 1 , wherein the sheet material is substantially air-impermeable and liquid water-impermeable.
22 . A material according to claim 1 , wherein the weight of the film is in the range of 10-150 grams per square meter.
23 . A material according to claim 1 , wherein the weight of the substrate is in the range of 15-350 grams per square meter.
24 . A material according to claim 1 , wherein the weight of the sheet material is in the range of 25-500 grams per square meter.
25 . A material according to claim 1 , wherein the sheet material has a moisture vapor transmission rate in the range of 35-1,200 grams per square meter per day.
26 . A material according to claim 1 , wherein the sheet material has an air resistance of at least 10,000 sec/100 cc.
27 . A material according to claim 1 , wherein the sheet material has a hydrostatic water head of at least 55 cm per AATCC 127.
28 . A material according to claim 1 , wherein the sheet material has a tensile strength in the range of 5-130 pounds per inch (34-896 kPa).
29 . A material according to claim 1 , wherein the film is monolithic.
30 . A material according to claim 1 , wherein the substrate is bonded to the film by reactive extrusion of the film directly onto the substrate.
31 . A material according to claim 1 , wherein the sheet material is for use as housewrap, roofing underlayment or flashing.
32 . A material according to claim 1 , wherein the sheet material is for use as breathable apparel, desiccant packaging, a surgical barrier, a medical wrap, a mattress cover, a pillow cover, a diaper, a humidifier membrane, a filter, or a gas containment structure.
33 . A method of making a water vapor-permeable sheet material, comprising the steps of:
(a) processing by a reactive extrusion process a blend comprising a first block copolymer which comprises a polyether block amide copolymer and a second block copolymer which comprises a copolyether ester, to produce an extruded film; and
(b) bonding the extruded film to a fibrous substrate to form the sheet material.
34 . A method according to claim 33 , wherein the reactive extrusion process is carried out at a temperature in the range of 430-600 degrees F.(238-277 degrees C.).
35 . A method according to claim 33 , wherein the reactive extrusion process is carried out for a residence time in the range of 5-220 seconds.
36 . A method according to claim 33 , wherein the reactive extrusion process is carried out for a residence time in the range of 5-100 seconds.
37 . A method according to claim 33 , wherein the step of bonding comprises extruding the film onto the substrate and passing the material through a nip.
38 . A method according to claim 37 , wherein the nip exerts a pressure in the range of 8-150 psi (55-1,034 kPa).
39 . A method according to claim 33 , wherein an air gap used in the reactive extrusion process is in the range of 3.5-10 inches (8.9-25.4 cm).
40 . A method according to claim 33 , wherein the first block copolymer comprises polyamide blocks and polyether blocks.
41 . A method according to claim 40 , wherein the polyamide block comprises polyamide 6 , 11 or 12.
42 . A method according to claim 40 , wherein the polyether block comprises a polyalkylene glycol.
43 . A material according claim 40 , wherein the polyether block comprises polyethylene glycol, polypropylene glycol or polytetramethylene glycol.
44 . A material according to claim 33 , wherein the first block copolymer is the product of polycondensation of a carboxylic acid polyamide with an alcohol termination polyether.
45 . A method according to claim 33 , wherein the first block copolymer is Pebax.
46 . A method according to claim 33 , wherein the second block copolymer comprises polyether blocks and polyester blocks.
47 . A method according to claim 46 , wherein the polyether blocks of the second block copolymer comprise a poly (alkylene oxide).
48 . A method according to claim 47 , wherein the poly (alkylene oxide) comprises polyethylene glycol, polypropylene glycol or polytetramethylene glycol.
49 . A method according to claim 46 , wherein the polyester blocks comprise a poly (alkylene terephthalate).
50 . A method according to claim 49 , wherein the poly (alkylene terephthalate) comprises polybutylene terephthalate or polyethylene terephthalate.
51 . A method according to claim 33 , wherein the second block copolymer comprises Arnitel.
52 . A method according to claim 33 , wherein the blend further comprises a compatibilizer.
53 . A method according to claim 52 , wherein the compatibilizer comprises a polymer functionalized by maleic anhydride grafting.
54 . A method according to claim 52 , wherein the compatibilizer comprises ethylene methyl acrylate copolymer.
55 . A method according to claim 33 , wherein the blend further comprises a colorant or a UV-inhibitor, or both.
56 . A method according to claim 33 , wherein the substrate is woven.
57 . A method according to claim 56 , wherein the substrate comprises polyethylene, polypropylene, polyethylene terephthalate, a polyamide, glass mat, felt, paper, or combinations thereof.
58 . A method according to claim 33 , wherein the substrate is non-woven.
59 . A method according to claim 33 , wherein the sheet material is substantially air-impervious and liquid water-impervious.