Contamination resistant air permeable fabric laminate and garments made therefrom

1. An air permeable fabric laminate comprising:

a. a hydrophobic asymmetric porous membrane comprising:

i. a first porous fluoropolymer membrane region having a first microstructure, and

ii. a second porous fluoropolymer membrane region having second microstructure, and

b. a textile attached by discontinuous attachments to the second porous fluoropolymer membrane region on a side opposite the first porous fluoropolymer membrane region,

wherein said first microstructure is a homogenous microstructure throughout said first porous fluoropolymer membrane region,

wherein said second microstructure is a homogenous microstructure throughout said second porous fluoropolymer membrane region, and said second microstructure is different than the first microstructure and said first microstructure is a tighter microstructure than said second microstructure, and

wherein the air permeable fabric laminate shows a change in opacity at a pressure of at least 30 kPa less than the pressure of the visible bubble point indication when testing for the change in opacity the first porous fluoropolymer membrane region is facing the top and an increased gas pressure is applied to the second porous fluoropolymer membrane region facing the bottom.

2. The air permeable fabric laminate of claim 1 having a liquid displacement pressure (LDP) greater than 10 kPa.

3. The air permeable fabric laminate of claim 1 having a liquid entry pressure greater than 70 kPa to a liquid having a surface tension of about 31 dynes/cm.

4. The air permeable fabric laminate of claim 1 wherein the asymmetric porous membrane has a Z-strength greater than 25 N.

5. The air permeable fabric laminate of claim 1 , wherein the first porous membrane region and second the porous membrane region each have a nodal density, and wherein the nodal density of the first porous membrane region is at least 10% greater than the nodal density of the second porous membrane region.

6. The air permeable fabric laminate of claim 1 , wherein the Gurley number is less than 200 seconds.

7. The air permeable fabric laminate of claim 1 , wherein the Gurley number is greater than 10 seconds.

8. The air permeable fabric laminate of claim 1 , wherein the Gurley number is greater than 10 seconds and less than 200 seconds.

9. The air permeable fabric laminate of claim 1 , wherein at least one said first porous expanded polytetrafluoroethylene membrane and said second porous expanded polytetrafluoroethylene membrane comprises an expanded modified PTFE membrane.

10. The air permeable fabric laminate of claim 1 , further comprising an oleophobic coating.

11. The air permeable fabric laminate of claim 10 , wherein the fabric laminate has a liquid entry pressure greater than 70 kPa to a liquid having a surface tension of about 31 dynes/cm.

12. The air permeable fabric laminate of claim 1 , wherein the asymmetric porous membrane comprises an oleophobic coating.

13. The air permeable fabric laminate of claim 1 , wherein the asymmetric porous membrane has an oil rating greater than 4.

14. The air permeable fabric laminate of claim 1 wherein the asymmetric porous membrane has a bubble point greater than 170 kPa.

15. The air permeable fabric laminate of claim 1 wherein the asymmetric porous membrane has a bubble point greater than 205 kPa.

16. The air permeable fabric laminate of claim 1 comprising an interface between the first porous membrane region and the second porous membrane region that forms a boundary that consists essentially of the materials of the first and second porous fluoropolymer membrane regions.

17. The air permeable fabric laminate of claim 1 wherein the fabric laminate has a weight of about 20 to about 500 gsm.

18. The air permeable fabric laminate of claim 1 wherein the asymmetric porous membrane has a weight between about 2 and 100 gsm.

19. The air permeable fabric laminate of claim 1 where in the laminate has an MVTR greater than about 10,000 g/m 2 -24 hours.

20. The air permeable fabric laminate of claim 1 further comprising a second textile layer attached to the asymmetric porous membrane on a side opposite the first textile.

21. The air permeable fabric laminate of claim 20 wherein the MVTR is greater than about 10,000 g/m 2 -24 hours.

22. The air permeable fabric laminate of claim 20 further comprising a water repellent coating.

23. A garment comprising:

a garment outer surface;

a garment inner surface designed to be oriented toward the body of a garment wearer in use; and

an air permeable fabric laminate comprising:

a. an asymmetric porous membrane comprising:

i. a first porous fluoropolymer membrane region having a first microstructure, and

ii. a second porous fluoropolymer membrane region having a second microstructure that is different than the first microstructure,

b. an outer textile, proximate to the garment outer surface, attached by discontinuous attachments to the asymmetric porous membrane; and

c. an inner textile, proximate to the garment inner surface, attached by discontinuous attachments to the asymmetric porous membrane on a side opposite the outer textile,

wherein said first microstructure is a homogenous microstructure throughout said first porous fluoropolymer membrane region,

wherein said second microstructure is a homogenous microstructure throughout said second porous fluoropolymer membrane region, and said second microstructure is different than the first microstructure and said first microstructure is a tighter microstructure than said second microstructure, and

wherein the garment has a change in opacity prior to a visible bubble point indication when the first porous fluoropolymer membrane region is facing the top tested with the inner textile facing gas pressure is applied to the second porous fluoropolymer membrane region facing the bottom.

24. The garment of claim 23 wherein the air permeable fabric laminate has a liquid entry pressure greater than 70 kPa with a fluid having a surface tension of about 31 dynes/cm.

25. The garment of claim 23 wherein the air permeable fabric laminate has a Gurley number less than 200 seconds.

26. The garment of claim 23 wherein the fabric laminate further comprises an oleophobic coating.

27. An asymmetric porous membrane comprising:

a first porous fluoropolymer membrane region having a first microstructure, and

a second porous fluoropolymer membrane region having a second microstructure,

wherein said first microstructure is a homogenous microstructure throughout said first porous fluoropolymer membrane region, and

wherein said second microstructure is a homogenous microstructure throughout said second porous fluoropolymer membrane region, and said second microstructure is different than the first microstructure and said first microstructure is a tighter microstructure than said second microstructure, and

wherein the asymmetric porous membrane has a change in opacity prior to a visible bubble point indication when testing for the change in opacity the first porous fluoropolymer membrane region is facing the top and an increased gas pressure is applied to the second porous fluoropolymer membrane region facing the bottom.

28. The asymmetric porous membrane of claim 27 wherein the asymmetric porous membrane has a Z-strength greater than 25N.

29. The asymmetric porous membrane of claim 27 , wherein the nodal density of the first porous fluoropolymer membrane region is at least 10% greater than the nodal density of the second porous fluoropolymer membrane region.

30. The asymmetric porous membrane of claim 27 , wherein at least one of said first porous fluoropolymer membrane region and said second porous fluoropolymer membrane region comprises an expanded modified polytetrafluoroethylene (PTFE) membrane.

31. The asymmetric porous membrane of claim 27 , wherein the asymmetric porous membrane comprises an oleophobic coating.

32. The asymmetric porous membrane of claim 27 , wherein the asymmetric porous membrane has an oil rating greater than 4.

33. The asymmetric porous membrane of claim 27 wherein the asymmetric porous membrane has a bubble point greater than 170 kPa.

34. The asymmetric porous membrane of claim 27 wherein the asymmetric porous membrane has a bubble point greater than 205 kPa.

35. The asymmetric porous membrane of claim 27 , further comprising an interface between the first porous fluoropolymer membrane region and the second porous fluoropolymer membrane region that forms a boundary that consists essentially of the materials of the first and second porous fluoropolymer membrane regions.

36. The asymmetric porous membrane of claim 27 , further comprising a third porous fluoropolymer membrane region.

37. The garment of claim 23 , further comprising a third porous expanded polytetrafluoroethylene membrane.

38. The air permeable fabric of claim 1 , further comprising a third porous expanded polytetrafluoroethylene membrane.