Patent ID: 7892694

Claim:
An electrolytic membrane comprising a porous membrane substrate comprising a cross-linked polymer electrolyte comprising a structural component represented by the following chemical formula 1: wherein A represents a repeating unit having an aromatic hydrocarbon group substituted by at least a sulfonic acid group, B represents a repeating unit having one of a nitrogen-comprising hetero ring compound residue, and the sulfate, hydrochloride or organic sulfonate thereof, C represents a repeating unit having a cross-linked group, and X, Y and Z represent mol fractions of respective repeating units in the chemical formula 1, with 0.34≦X≦0.985, 0.005≦Y≦0.49, 0.01≦Z≦50.495 and Y≦X and Z≦X, provided that, in the repeating unit A, a ratio of the aromatic hydrocarbon group substituted by at least a sulfonic acid group is 0.3 to 1.0, and the number of the sulfonic acid group in the aromatic hydrocarbon group substituted by at least a sulfonic acid group is 1 to 3, and wherein the porous membrane substrate comprises at least one high molecular material selected from the group consisting of polyethylene, polypropylene, polyimide, polyamidimide, polyvinylidene fluoride and polytetrafluoroethylene.