Ultra-thin integral composite membrane

• US 5,547,551 A
• Filed: 03/15/1995
• Issued: 08/20/1996
• Est. Priority Date: 03/15/1995
• Status: Expired due to Term

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Inventors: Zuckerbrod, David, Kolde, Jeffrey A., Bahar, Bamdad, Hobson, Alex R.
• Primary Examiner(s): GORGOS, KATHRYN L
• Application Number:
  US08/404,853
• Time in Patent Office: 524 Days
• Field of Search: 204/296, 204/301, 204/299 R, 210/500.36, 210/500.1, 429/30, 429/33, 521/27
• US Class Current: 204/296
• CPC Class Codes: B01D 67/0088 Physical treatment with compounds, e.g. swelling, coating or impregnation
• CPC Class Codes: B01D 69/141 Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
• CPC Class Codes: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 5/225 containing fluorine
• CPC Class Codes: C25B 13/08 based on organic materials
• CPC Class Codes: H01M 8/1023 having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
• CPC Class Codes: H01M 8/1039 halogenated, e.g. sulfonated polyvinylidene fluorides
• CPC Class Codes: H01M 8/1044 Mixtures of polymers, of which at least one is ionically conductive
• CPC Class Codes: H01M 8/106 characterised by the chemical composition of the porous support
• CPC Class Codes: H01M 8/1062 characterised by the physical properties of the porous support, e.g. its porosity or thickness
• CPC Class Codes: Y02E 60/50 Fuel cells

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) and a microstructure characterized by nodes 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

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; 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 and a total thickness of less than 13 μ

m; 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.

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 μ

m.

17. The ion exchange membrane of claim 16, and wherein the average pore size is less than 0.2 μ

m.

18. The ion exchange membrane of claim 16, and wherein the total thickness of the membrane is less 13 μ

m.

19. The ion exchange membrane of claim 18 and wherein the total thickness of the membrane is from about 1.32 μ

m to about 12.7 μ

m.

20. The ion exchange membrane of claim 15, 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.

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 polypropylene.