Process for producing ion exchange membranes by melt-processing of acidic PFSA ionomers

Patent metadata

Field	Value
Publication number	US-9543607-B2
Application number	US-201414187907-A
Country	US
Kind code	B2
Filing date	Feb 24, 2014
Priority date	Feb 22, 2013
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A process for producing an ion exchange membrane involves melt-processing a mixture of a perfluorosulfonic acid ionomer in its acid form and a specific azole additive. The additive may be a triazole, alkyl triazole, vinyl triazole, fluoro-alkyl triazole, fluoro-vinyl triazole, pyrazole, alkyl pyrazole, vinyl pyrazole, fluoro-alkyl pyrazole, fluoro-vinyl pyrazole, benzimidazole, alkyl benzimidazole, vinyl benzimidazole, fluoro-alkyl benzimidazole, fluoro-vinyl benzimidazole or any mixture thereof to form a film having a thickness of from 3 to 200 microns. Ion exchange membranes so produced have reduced in-plane-swelling, improved dimensional stability and mechanical properties, and are useful as electrolytes in proton exchange membrane fuel cells.

First claim

What is claimed is:

1. A process for producing an ion exchange membrane comprising: melt-processing a mixture of a perfluorosulfonic acid ionomer in its acid form and an additive comprising triazole, alkyl triazole, vinyl triazole, fluoro-alkyl triazole, fluoro-vinyl triazole, pyrazole, alkyl pyrazole, vinyl pyrazole, fluoro-alkyl pyrazole, fluoro-vinyl pyrazole, benzimidazole, alkyl benzimidazole, vinyl benzimidazole, fluoro-alkyl benzimidazole, fluoro-vinyl benzimidazole or any mixture thereof that is non-volatile, and thermally stable at a temperature of the melt-processing, to form a film having a thickness of from 3 to 200 microns.

2. The process according to claim 1 , wherein the additive comprises 1,2,4-triazole, benzimidazole or a mixture thereof.

3. The process according to claim 1 , wherein the additive comprises 1,2,4-triazole.

4. The process according to claim 1 , further comprising removing the additive from the film after melt-processing.

5. The process according to claim 4 , wherein the additive is removed by dissolving it in a solvent.

6. The process according to claim 5 , wherein the solvent comprises water or an aqueous solution.

7. The process according to claim 5 , wherein the aqueous solution is a solution of sulfuric acid.

8. The process according to claim 1 , wherein the melt-processing comprises melt-extrusion, melt-casting or melt-blowing.

9. The process according to claim 1 , wherein the additive is first dissolved in an aqueous solution before melt-processing with the perfluorosulfonic acid ionomer.

10. The process according to claim 1 , wherein the perfluorosulfonic acid ionomer is pre-swollen before melt-processing with the additive.

11. A process according to claim 1 , wherein the perfluorosulfonic acid ionomer is a perfluorosulfonic acid-polytetrafluoroethylene copolymer of Formula (II):

wherein the number of repeat units x and y are such that there are less than 15 x units for each y and the value of m and n are integers between 0 and 5.

12. An ion exchange membrane made by the process of claim 1 .

13. The membrane according to claim 12 , wherein the film has a thickness of from 3 to 95 microns.

14. The membrane according to claim 12 , wherein the length and/or width changes by less than 7.5%.

15. The membrane according to claim 12 , wherein the film consists of the perfluorosulfonic acid ionomer.

16. An electrochemical device comprising an electrolyte comprising the membrane as defined in claim 12 .

17. The device according to claim 16 which is a polymer electrolyte membrane fuel cell.

18. The membrance according to claim 12 , wherein the perfluorosulfonic acid ionomer is a perfluorosulfonic acid-polytetrafluoroethylene copolymer of Formula (II):

wherein the number of repeat units x and y are such that there are less than 15 x units for each y and the value of m and n are integers between 0 and 5.

Assignees

• Nat Res Council Canada

Inventors

• Mokrini Asmae

Classifications

• H01M8/1039 Primary

  halogenated, e.g. sulfonated polyvinylidene fluorides · CPC title

• H01M8/1069

  characterised by the manufacturing processes · CPC title

• H01M8/1086

  After-treatment of the membrane other than by polymerisation · CPC title

• C08J5/2237

  containing fluorine · CPC title

• C08J5/22

  Films, membranes or diaphragms · CPC title