Porous PTFE Materials and Articles Produced Therefrom

Abstract

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.