PROCESS FOR PRODUCING POLYMERIC ELECTROLYTE MEMBRANE

• US 20120003564A1
• Filed: 01/15/2010
• Published: 01/05/2012
• Est. Priority Date: 01/19/2009
• Status: Active Grant

• Current Assignee: Toray Industries Incorporated
• Original Assignee: Toray Industries Incorporated
• Inventors: Adachi, Shinya, Kidai, Masayuki, Hara, Mayumi, Kawakami, Tomonori
• Granted Patent: US 9,059,448 B2
• Time in Patent Office: Days
• US Class Current: 429/492
• CPC Class Codes: C08J 2371/10 from phenols
• CPC Class Codes: C08J 5/2256 based on macromolecular compounds obtained by reactions other than those involving carbon-to-carbon bonds, e.g. obtained by polycondensation
• CPC Class Codes: H01M 8/1023 having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
• CPC Class Codes: H01M 8/1067 characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
• CPC Class Codes: H01M 8/1079 Inducing porosity into non porous precursors membranes, e.g. leaching, pore stretching
• CPC Class Codes: H01M 8/1081 starting from solutions, dispersions or slurries exclusively of polymers
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 20/582 Recycling of unreacted starting or intermediate materials
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Disclosed is a method for producing a polymer electrolyte membrane, which comprises the steps of: removing a part of a salt component produced during polycondensation from a polymerization solution of a polymer electrolyte having a density of an ionic group of 2 mmol/g or more directly by centrifugal separation, thereby preparing a coating solution; applying the coating solution on a substrate by casting; removing a part of a solvent from the coating solution to form a film-shaped material on the substrate; and bringing the film-shaped material on the substrate into contact with water and/or an aqueous acidic solution to remove the salt component produced during the polycondensation. According to the method for producing an electrolyte membrane, even an electrolyte having a high density of an ionic group can be purified. Also disclosed is an electrolyte membrane capable of being used in a fuel cell which is operated at a high temperature higher than 80° C. and under low humidity conditions having a relative humidity of 60% or less.

Claims

1. A method for producing a polymer electrolyte membrane, comprising:

removing at least a part of a salt component produced during polycondensation from a polymerization solution of a polymer electrolyte having a density of an ionic group of 2 mmol/g or more, thereby preparing a coating solution;

applying the coating solution on a substrate;

removing at least a part of a solvent from the coating solution to form a film-shaped material on the substrate; and

bringing the film-shaped material on the substrate into contact with water and/or an aqueous acidic solution to remove at least a portion of the salt component produced during the polycondensation.

2. The method for producing a polymer electrolyte membrane according to claim 1, wherein C3<

5, and C4/C3<

0.3, when a concentration of the salt component contained in the film-shaped material on the substrate by removing at least a part of said solvent is denoted by C3% by weight, and a concentration of the salt component after bringing the film-shaped material on the substrate into contact with water and/or an aqueous acidic solution to remove at least a portion of the salt component produced during polycondensation is denoted by C4% by weight.

3. The method for producing a polymer electrolyte membrane according to claim 1, further comprising adding a cyclic metal scavenger and/or glycols prior to the applying the coating solution onto the substrate, and eliminating the cyclic metal scavenger and/or glycols after the removing at least a part of the solvent to form the film-shaped material on the substrate.

4. The method for producing a polymer electrolyte membrane according to claim 1, further comprising desalting and polycondensing a monomer containing a metal salt of an ionic group by adding a cyclic metal scavenger and/or glycols.

5. The method for producing a polymer electrolyte membrane according to claim 1, wherein the film-shaped material on the substrate is brought into contact with water and/or an aqueous acidic solution comprising a solvent having a concentration of 5% by weight or more and 50% by weight or less, thereby removing at least a portion of the salt component produced during polycondensation.

6. The method for producing a polymer electrolyte membrane according to claim 1, wherein the film-shaped material on the substrate is brought into contact with water and/or an aqueous acidic solution without peeling the film-shaped material from the substrate to remove at least a portion of the salt component produced during polycondensation.

7. The method for producing a polymer electrolyte membrane according to claim 1, wherein said polymer electrolyte comprises an aromatic hydrocarbon electrolyte containing a hydrolytic group for imparting solubility.

8. The method for producing a polymer electrolyte membrane according to claim 3, wherein said cyclic metal scavenger comprises crown ether.

9. The method for producing a polymer electrolyte membrane according to claim 3, wherein said glycols are polyhydric alcohols or polyethylene glycols having a molecular weight of 500 or less.

10. The method for producing a polymer electrolyte membrane according to claim 1, wherein a peak of 133 ppm of said polymer electrolyte membrane, measured by solid 13C DD/MAS NMR spectrum, has a half width of 700 Hz or less.

11. An assembled polymer electrolyte membrane containing a polymer electrolyte membrane produced by the method for producing a polymer electrolyte membrane according to claim 1, and a porous film having a porosity of 60% or more and a Gurley permeability of 1000 seconds/100 cc or less.

12. The assembled polymer electrolyte membrane according to claim 11, wherein the porous film is a biaxially oriented porous polypropylene film.

13. The assembled polymer electrolyte membrane according to claim 11, wherein a change rate of dimension in a direction of plane is 5% or less and a density of an ionic group is 1.5 mmol/g or more when the assembled polymer electrolyte membrane is immersed in hot water of 80°

C. for 24 hours.

14. The method for producing a polymer electrolyte membrane according to claim 1, wherein the removing a part of a salt component produced during polycondensation from a polymerization solution of a polymer electrolyte having a density of an ionic group of 2 mmol/g or more is done by centrifugal separation.

15. The method for producing a polymer electrolyte membrane according to claim 1, wherein the applying the coating solution on a substrate is done by casting.

16. The method for producing a polymer electrolyte membrane according to claim 1, wherein the bringing the film-shaped material on the substrate into contact with water and/or an aqueous acidic solution to remove at least a portion of the salt component produced during the polycondensation comprises removing a substantial portion of the salt component produced during the polycondensation.

17. The assembled polymer electrolyte membrane according to claim 11, wherein C3<

5, and C4/C3<

0.3, when a concentration of the salt component contained in the film-shaped material on the substrate by removing at least a part of said solvent is denoted by C3% by weight, and a concentration of the salt component after bringing the film-shaped material on the substrate into contact with water and/or an aqueous acidic solution to remove at least a portion of the salt component produced during polycondensation is denoted by C4% by weight