Patent ID: 7396607

Claim:
A process of manufacturing membrane-electrode assemblies, said process comprising forming an electrolyte membrane by a film casting method in which a solution of a proton conductive polymer in a first organic solvent is flow cast on a film-casting substrate to form a wet film, and the electrolyte membrane is obtained by reducing an amount of residual solvent in the wet film, wherein the electrolyte membrane contains residual solvent in an amount of 1 part by weight or less based on 100 parts by weight of the proton conductive polymer; applying a second solvent to at least one facing surface of an electrode substrate and the electrolyte membrane; and then pressure bonding said electrolyte membrane with said electrode substrate to form a membrane-electrode assembly, wherein the second solvent is applied in an amount of from 0.001 mg/cm 2 to 10 mg/cm 2 .