Fluororesin-Coated Polymer Film For Reinforcing Polymer Electrolyte Membrane, Reinforced Polymer Electrolyte Membrane, and Membrane Electrode Assembly

Abstract

Disclosed is a fluororesin-coated polymer film for reinforcing a polymer electrolyte membrane, wherein the fluororesin-coated polymer film is fabricated by forming on at least one side of a polymer film a coating of a reaction product of (A) a fluorine-containing copolymer composed of a fluoroolefin, a cyclohexyl group-containing acrylic ester, and a hydroxyl group-containing vinyl ether, and (B) a crosslinking agent having two or more isocyanate groups. The polymer film according to the present invention not only exhibits sufficiently high initial adhesion strength, with respect to the polymer electrolyte membrane, but also retains thereafter high adhesion strength in actual operating environments.

What is claimed is: 
     
         1 . A fluororesin-coated polymer film for reinforcing a polymer electrolyte membrane, wherein said fluororesin-coated polymer film is fabricated by forming on at least one side of a polymer film a coating of a reaction product of (A) a fluorine-containing copolymer composed of a fluoroolefin represented by formula (1) below, a cyclohexyl group-containing acrylic ester represented by formula (2) below, and a hydroxyl group-containing vinyl ether represented by formula (3) below, and (B) a crosslinking agent having two or more isocyanate groups, said formulas (1), (2), and (3) being given as 
       
         
           
           
               
               
           
         
       
       (where X is F or H, and Y is H, Cl, F, or CF 3 ) 
       
         
           
           
               
               
           
         
       
       (where R 1  is a hydrogen or methyl group), and 
       
         
           
           
               
               
           
         
       
       (where R 2  is an alkylene group with a carbon number of 2 to 5 or a cyclohexylene group). 
     
     
         2 . The fluororesin-coated polymer film as claimed in  claim 1 , wherein said fluorine-containing copolymer (A) contains 40 to 90 mole % of said fluoroolefin, 1 to 30 mole % of said cyclohexyl group-containing acrylic ester, and 1 to 30 mole % of said hydroxyl group-containing vinyl ether.