Porous PTFE Materials and Articles Produced Therefrom
Novel porous PTFE membranes are described possessing a unique combination of high strength, low flow resistance, and small pore size. Additionally, unique constructions with superior filtration and venting properties incorporating porous PTFE membranes are described.
1 . An article comprising an expanded PTFE membrane having a membrane surface area of at least 17 m 2 /g.
2 . The article of claim 1 , wherein said PTFE membrane has a light transmission through the membrane of greater than 50%.
3 . The article of claim 1 , wherein the PTFE membrane surface area is at least 20 m 2 /g.
4 . The article of claim 1 , wherein the PTFE membrane surface area is at least 23 m 2 /g.
5 . An article comprising an expanded PTFE membrane having a light transmission through the membrane of at least 50% and a porosity of at least 50%.
6 . The article of claim 5 , wherein the expanded PTFE membrane has a light transmission through the membrane of at least 85% and a porosity of at least 75%.
7 . An article comprising an expanded PTFE membrane having a water entry pressure versus Gurley equal to or above the line defined by the equation WEP=3(Gurley)+2500.
8 . The article of claim 7 , wherein the expanded PTFE membrane has a water entry pressure equal to or above the line defined by the equation WEP=3(Gurley)+2900.
9 . The article of claim 7 , further comprising at least one additional layer selected from the group consisting of non-woven, scrim and fabric.
10 . The article of claim 7 , further comprising at least one additional layer on each side of the PTFE membrane.
11 . The article of claim 10 , wherein said at least one additional layer comprises at least one porous membrane.
12 . The article of claim 11 , wherein said at least one additional layer comprises ePTFE.
13 . The article of claim 7 in the form of a filter.
14 . The article of claim 7 in the form of a vent.
15 . The article of claim 7 in the form of a filter cartridge.
16 . An article comprising expanded PTFE membrane which is instantly wettable with water, said membrane having a water flux rate versus bubble point equal to or above the line defined by the equation log (water flux rate)=−0.01 (bubble point)+1.3.
17 . The article of claim 16 , having a water flux rate versus bubble point equal to or above the line defined by the equation log (water flux rate)=−0.01 (bubble point)+2.48.
18 . The article of claim 16 in the form of a filter cartridge.
19 . An article comprising an expanded PTFE membrane having a water flux rate versus bubble point equal to or above the line defined by the equation log (water flux rate)=−3.5×10 −3 (bubble point)+1.3 and a surface area of at least 17 m 2 /g.
20 . The article of claim 19 , wherein the water flux rate versus bubble point is equal to or above the line defined by the equation log (water flux rate)=−3.5×10 −3 (bubble point)+1.6.
21 . The article of claim 19 in the form of a filter cartridge.