SOLID POLYMER ELECTROLYTE MEMBRANE, MEMBRANE ELECTRODE ASSEMBLY FOR SOLID POLYMER FUEL CELL, AND METHOD FOR PRODUCING SOLID POLYMER ELECTROLYTE MEMBRANE

The present invention provides a polymer electrolyte membrane and a membrane-electrode assembly for polymer electrolyte fuel cells excellent in dimensional stability against change of the water content and mechanical strength. The present invention provides a polymer electrolyte membrane (1) characterized by comprising at least one filled layer (34) of a perforated sheet (10) having many through-holes formed substantially in parallel to the thickness direction with an average cross-sectional area of from 1×10 -3 to 20 mm 2 , wherein the numerical aperture based on the through-holes is from 30 to 80%, and an ion exchange resin is filled in the through-holes (11). Further, the present invention provides a polymer electrolyte membrane (1) characterized by comprising at least one filled layer (34) of a perforated sheet (20) in which the center portion is a region 1 (201) which is the same as the above perforated sheet (10) and the peripheral portion is a region 2 (202) which has a lower numerical aperture than the above region 1 or no through-holes, and wherein an ion exchange resin is filled in the perforated sheet (20). Such a polymer electrolyte membrane (1) is excellent in the dimensional stability against change of the water content and the mechanical strength. Accordingly, the membrane-electrode assembly (6) for polymer electrolyte fuel cells having the polymer electrolyte membrane (1) has high reliability and excellent durability.