Phosphoric acid group-containing polymer electrolyte (composite) membrane and its production method

Abstract

The invention relates to solid polyelectrolyte membranes and processes for their production. As solid polyelectrolyte materials, there have been known fluoropolymers which have perfluoroskeletons and side chains bearing sulfonic acid groups and heat-resistant resins which have hydrocarbon skeletons and contain alkylsulfonic acid or alkylphosphoric acid groups introduced thereto. The fluoropolymers are excellent in heat resistance and chemical resistance but have the problem of being expensive, while the heat-resistant resins have the problem of being poor in chemical resistance. Further, solid polyelectrolyte materials having higher electric conductivities have been desired. With the purpose of providing solid polyelectrolyte membranes having satisfactorily high electric conductivities and being excellent in heat resistance and chemical resistance and processes for producing the membranes, solid polyelectrolyte membranes are made from resins bearing both phosphoric acid groups and sulfonic acid groups which resins are obtained by copolymerizing a monomer bearing in the molecule a phosphoric acid group and an ethylenically unsaturated bond with a monomer bearing in the molecule a sulfonic acid group and an ethylenically unsaturated bond.

1 .- 43 . (canceled)  
   
   
       44 . A fuel cell comprising a solid polymer electrolyte membrane as a proton-conductive polymer, said solid polymer electrolyte membrane made of a phosphoric acid group/sulfonic acid group-containing resin, which is a copolymer of a phosphoric acid group-containing, unsaturated monomer having at least one phosphoric acid group and at least one ethylenic unsaturated bond in a molecule and a sulfonic acid group-containing, unsaturated monomer having at least one sulfonic acid group and at least one ethylenic unsaturated bond in a molecule.  
   
   
       45 . A fuel cell according to  claim 44 , wherein said phosphoric acid group-containing, unsaturated monomer is represented by the following general formula (A):  
     
       
         
         
             
             
         
       
     
   
   
       46 . The fuel cell according to  claim 45 , wherein R 1  represents H or CH 3 , and R 2  represents H, CH 3  or CH 2 Cl.  
   
   
       47 . The fuel cell according to  claim 44 , wherein said sulfonic acid group-containing, unsaturated monomer is p-styrene sulfonic acid.  
   
   
       48 . A fuel cell comprising a solid polymer electrolyte membrane as a proton-conductive polymer, said solid polymer electrolyte membrane comprising a phosphoric acid group/sulfonic acid group-containing resin and a reinforcing sheet; wherein said phosphoric acid group/sulfonic acid group-containing resin is a copolymer of a phosphoric acid group-containing, unsaturated monomer having at least one phosphoric acid group and at least one ethylenic unsaturated bond in a molecule and a sulfonic acid group-containing, unsaturated monomer having at least one sulfonic acid group and at least one ethylenic unsaturated bond in a molecule.  
   
   
       49 . The fuel cell according to  claim 48 , wherein said phosphoric acid group-containing, unsaturated monomer is represented by the following general formula (A):  
     
       
         
         
             
             
         
       
     
     wherein R 1  represents hydrogen or an alkyl group, R 2  represents hydrogen or a substituted or unsubstituted alkyl group, and n represents an integer of 1 to 6.  
   
   
       50 . The fuel cell according to  claim 49 , wherein R 1  represents H or CH 3 , and R 2  represents H, CH 3 , or CH 2 Cl.  
   
   
       51 . The fuel cell according to  claim 48 , wherein said sulfonic acid group-containing, unsaturated monomer is p-styrene sulfonic acid.  
   
   
       52 . The fuel cell according to  claim 48 , wherein said reinforcing sheet is a sheet constituted by inorganic or organic fibers.  
   
   
       53 . The fuel cell according to  claim 52 , wherein said reinforcing sheet is a woven fabric, a non-woven fabric or a paper.  
   
   
       54 . The fuel cell according to  claim 48 , wherein said reinforcing sheet is a resin film.  
   
   
       55 . The fuel cell according to  claim 54 , wherein said resin film is microporous.