P
USRE37307EExpiredUtilityPatentIndex 95

Ultra-thin integral composite membrane

Assignee: GORE & ASSPriority: Nov 14, 1994Filed: Aug 20, 1998Granted: Aug 7, 2001
Est. expiryNov 14, 2014(expired)· nominal 20-yr term from priority
Inventors:BAHAR BAMDAD AMALLOUK ROBERT SHOBSON ALEX RKOLDE JEFFREY A
H01M 50/497H01M 50/491H01M 50/489H01M 50/414B01D 69/1411C08J 2327/18H01M 8/1039H01M 8/1053H01M 8/1044C08J 5/225B01D 67/0088C25B 13/08H01M 8/1023B32B 5/18H01M 8/1067H01M 8/106H01M 8/1062Y02E60/10Y02E60/50
95
PatentIndex Score
98
Cited by
86
References
51
Claims

Abstract

An ultra-thin composite membrane is provided which includes a base material and an ion exchange resin. The base material is a membrane which is defined by a thickness of less than 1 mil (0.025 mm) 0.8 mils and a microstructure characterized by node interconnected by fibrils, or a microstructure characterized by fibrils with no nodes present. The ion exchange resin substantially impregnates the membrane such that the membrane is essentially air impermeable.

Claims

exact text as granted — not AI-modified
We claim:  
     
       1. An ultra-thin composite membrane comprising: 
       (a) an expanded polytetrafluoroethylene membrane having a porous microstructure of polymeric fibrils and a total thickness of less than 0.025 mm   0 . 8  mils; and  
       (b) an ion exchange material impregnated throughout the membrane, the impregnated expanded polytetrafluoroethylene membrane having a Gurley number of greater than 10,000 seconds, wherein the ion exchange material substantially impregnates the membrane to render an interior volume of the membrane substantially occlusive.  
     
     
       2. The ultra-thin composite membrane of claim  1 , and wherein the membrane comprises a microstructure of nodes interconnected by fibrils. 
     
     
       3. The ultra-thin composite membrane of claim  1 , and wherein the ion exchange material is selected from a group consisting of perfluorinated sulfonic acid resin, perfluorinated carboxylic acid resin, polyvinyl alcohol, divinyl benzene, styrene-based polymers, and metal salts with or without a polymer. 
     
     
       4. The ultra-thin composite membrane of claim  1 , and wherein the ion exchange material is a perfluorosulfonic acid/tetrafluoroethylene copolymer resin dissolved in a solvent solution selected from a group consisting of water, ethanol, propanol, butanol, methanol, and combinations thereof. 
     
     
       5. The ultra-thin composite membrane of claim  1 , further comprising a reinforcement backing bonded to the membrane wherein the reinforcement backing is selected from a group consisting of woven and nonwoven materials. 
     
     
       6. The ultra-thin composite membrane of claim  5 , and wherein the woven materials are selected from the group consisting of: weaves of expanded porous polytetrafluoroethylene fibers, webs of polypropylene, and netting of polypropylene. 
     
     
       7. The ultra-thin composite membrane of claim  5 , and wherein the nonwoven material is spun-bonded polypropylene. 
     
     
       8. An ultra-thin composite membrane comprising: 
       (a) a membrane having a porous microstructure of polymeric fibrils and a total thickness of less than 13 μm   0 . 51  mils; and  
       (b) an ion exchange material impregnated throughout the membrane, the impregnated expanded polytetrafluoroethylene membrane having a Gurley number of greater than 10,000 seconds, wherein the ion exchange material substantially impregnates the membrane to render an interior volume of the membrane substantially occlusive.  
     
     
       9. The ultra-thin composite membrane of claim  8 , and wherein the membrane is expanded polytetrafluoroethylene. 
     
     
       10. The ultra-thin composite membrane of claim  8 , and wherein the ion exchange material is selected from a group consisting of perfluorinated sulfonic acid resin, perfluorinated carboxylic acid resin, polyvinyl alcohol, divinyl benzene, styrene-based polymers, and metal salts with or without a polymer. 
     
     
       11. The ultra-thin composite membrane of claim  8 , and wherein the ion exchange material is a perfluorosulfonic acid/tetrafluoroethylene copolymer resin dissolved in a solvent solution selected from a group consisting of water, ethanol, propanol, butanol, methanol and combinations thereof. 
     
     
       12. The ultra-thin composite membrane of claim  8 , further comprising a reinforcement backing bonded to the membrane wherein the reinforcement backing is selected from a group consisting of woven and nonwoven materials. 
     
     
       13. The ultra-thin composite membrane of claim  12 , and wherein the woven materials are selected from a group consisting of: weaves of expanded porous polytetrafluoroethylene fibers, webs of polypropylene, and netting of polypropylene. 
     
     
       14. The ultra-thin composite membrane of claim  12 , and wherein the nonwoven material is spun-bonded polypropylene. 
     
     
       15. An ion exchange membrane comprising: 
       (a) a membrane comprising an expanded polytetrafluoroethylene having a porous microstructure defined substantially of only fibrils; and  
       (b) an ion exchange material impregnated throughout the membrane, the impregnated expanded polytetrafluoroethylene membrane having a Gurley number of greater than 10,000 seconds, wherein the ion exchange material substantially impregnates the membrane to render an interior volume of the membrane substantially occlusive, said membrane having a total thickness within the range of between  0 . 06  mils and about  0 . 5  mils.  
     
     
       16. The ion exchange membrane of claim  15  wherein the porous microstructure of the membrane defines pores having an average size of from about 0.05 to about 0.4 μm. 
     
     
       17. The ion exchange membrane of claim  16 , and wherein the average pore size is less than 0.2 μm. 
     
     
       18. The ion exchange membrane of claim  16 , and wherein the total thickness of the membrane is less 13 μm. 
     
     
       19. The ion exchange membrane of claim  18  and wherein the total thickness of the membrane is from about 1.32 μm to about 12.7 μm. 
     
     
       20. The ion exchange membrane of claim  15 , and wherein the ion exchange material is selected from a group consisting of polyfluorinated sulfonic acid resin, perfluorinated carboxylic acid resin, polyvinyl alcohol, divinyl benzene, styrene-based polymers, and metal salts with or without a polymer. 
     
     
       21. The ion exchange membrane of claim  15 , and wherein the ion exchange material is a perfluorosulfonic acid/tetrafluoroethylene copolymer resin dissolved in a solvent solution selected from a group including water, ethanol, propanol, butanol, methanol, and combinations thereof. 
     
     
       22. The ion exchange membrane of claim  15 , further comprising a reinforcement backing bonded to the porous polymeric membrane, wherein the reinforcement backing is selected from a group consisting of woven and nonwoven materials. 
     
     
       23. The ion exchange membrane of claim  22 , and wherein the woven materials are selected from a group consisting of: weaves of expanded porous polytetrafluoroethylene fibers, webs of polypropylene, and netting of polypropylene. 
     
     
       24. The ion exchange membrane of claim  22 , and wherein the nonwoven material is spun-bonded polyproyplene. 
     
     
       25. A composite, ultra- thin, substantially non - porous membrane consisting essentially of:    
       ( a )  a polytetrafluoroethylene base having a pore structure defined by at least fibrils, said pore structure defining a porosity of at least  70   %  within said base; and    
       ( b )  an ion exchange resin contained within said pore structure and substantially filling said pore structure, such that the composite membrane has a Gurley number which exceeds  10 , 000  seconds, said composite membrane having a thickness no greater than  0 . 8  mils.    
     
     
       26. The composite membrane of claim  25 , wherein said pore structure is defined by nods interconnected with said fibrils.  
     
     
       27. The composite membrane of claim  25 , wherein said composite membrane has a thickness between the range of about  0 . 06  and  0 . 8  mils.  
     
     
       28. The composite membrane of claim  25 , wherein said composite membrane has a thickness between the range of  0 . 3  and about  0 . 5  mils.  
     
     
       29. The composite membrane of claim  25 , wherein said composite membrane has a thickness of not more than about  0 . 5  mils.  
     
     
       30. The composite membrane of claim  25 , wherein said ion exchange resin is a mixture of ion exchange resins.  
     
     
       31. The composite membrane of claim  25 , wherein said ion exchange resin is a perfluorinated sulfonic acid resin.  
     
     
       32. A composite, substantially non- porous membrane consisting essentially of:    
       ( a )  a polytetrafluoroethylene base having a pore structure defined by at least fibrils, said pore structure defining a porosity of at least  70   %  within said base; and    
       ( b )  an ion exchange resin contained within said pore structure and substantially filling said pore structure, such that the composite membrane has a Gurley number which exceeds  10 , 000  seconds, said composite membrane having a thickness of at most  0 . 8  mils and an ionic conductance of at least  8 . 5  mhos/cm   2   .    
     
     
       33. The composite membrane of claim  32 , which has a thickness between the range of about  0 . 06  and  0 . 8  mils.  
     
     
       34. The composite membrane of claim  32 , which has a thickness between the range of about  0 . 5  and  0 . 8  mils.  
     
     
       35. The composite membrane of claim  32 , which has a thickness at most about  0 . 5  mils.  
     
     
       36. The composite membrane of claim  32 , where said ion exchange resin is a perfluorosulfonic acid/tetrafluoroethylene copolymer resin.  
     
     
       37. A supported, composite membrane consisting essentially of: 
       ( a )  a porous support material; and    
       ( b )  a composite, ultra - thin, substantially non - porous membrane, said composite membrane having a polytetrafluoroethylene base having a pore network formed by at least fibrils, said pore network defining a porosity of at least  70   %  within said base; and    
       ( c )  an ion exchange resin contained within said pore network and substantially filling said pore network, such that the composite membrane has a Gurley number which exceeds  10 , 000  seconds and said composite membrane has a thickness no greater than  0 . 8  mils.    
     
     
       38. The supported composite membrane of claim  37 , wherein said pore network is formed by nodes interconnected with said fibrils.  
     
     
       39. The composite membrane of claim  31 , wherein said composite membrane which has a thickness between the range of about  0 . 06  and  0 . 8  mils.  
     
     
       40. The composite membrane of claim  37 , wherein said composite membrane which has a thickness between the range of about  0 . 5  and  0 . 8  mils.  
     
     
       41. The composite membrane of claim  37 , wherein said composite membrane which has a thickness of at most about  0 . 5  mils.  
     
     
       42. The composite membrane of claim  37 , wherein said ion exchange resin is a perfluorinated sulfonic acid resin.  
     
     
       43. The composite membrane of claim  37 , where said ion exchange resin is a mixture of ion exchange resins.  
     
     
       44. A composite, ultra- thin, substantially non - porous membrane having a total thickness of at most  0 . 8  mils having a polytetrafluoroethylene base with a pore structure defining a porosity of at least  70   %  within said base, at least one ion exchange resin contained within said pore structure such that said composite membrane has a Gurley number which exceeds  10 , 000  seconds, and is prepared by the process comprising the steps of:    
       ( a )  providing a polytetrafluoroethylene membrane having polytetrafluoroethylene base and a thickness of at most  0 . 8  mils and having a pore structure defining a porosity of at least  70   %  within said base; and    
       ( b )  applying an ion exchange resin containing solution to each side of said polytetrafluoroethylene base to substantially fill said pore structure.    
     
     
       45. The composite membrane of claim  44 , wherein said process further comprises: 
       ( c )  repeating step  ( b )  until said ion exchange resin substantially fills said pore structure.    
     
     
       46. The composite membrane of claim  44 , wherein said composite membrane has a thickness in the range of between about  0 . 06  and  0 . 8  mils.  
     
     
       47. The composite membrane of claim  44 , wherein said composite membrane has a thickness in the range between about  0 . 5  to  0 . 8  mils.  
     
     
       48. The composite membrane of claim  44 , wherein said step ( b )  is repeated at least two times.    
     
     
       49. The composite membrane of claim  44 , wherein said step ( b )  is repeated at least three times.    
     
     
       50. The composite membrane of claim  44 , wherein step ( b )  further comprises:    
       ( i )  first applying said ion exchange resin containing solution to a first side of said polytetrafluoroethylene base and then evaporating solvent in said solution; and    
       ( ii )  thereafter, applying said ion exchange resin containing solution to a second side of said polytetrafluoroethylene base and then evaporating solvent in said solution.    
     
     
       51. The composite membrane of claim  50 , wherein said process further includes the step of: 
       ( c )  heating said polytetrafluoroethylene base containing ion exchange resin within said pore structure.

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