FLUOROSULFONYL GROUP-CONTAINING FLUOROPOLYMER AND METHOD FOR PRODUCING SAME, SULFONIC ACID GROUP-CONTAINING FLUOROPOLYMER AND METHOD FOR PRODUCING SAME, SOLID POLYMER ELECTROLYTE MEMBRANE, MEMBRANE ELECTRODE ASSEMBLY, AND SOLID POLYMER FUEL CELL

摘要

The present invention provides: a fluorosulfonyl group-containing fluoropolymer capable of producing a solid polymer electrolyte membrane having excellent conductivity and hot water resistance, and a method for producing same; an acid-type sulfonic acid group-containing fluoropolymer and a method for producing same; a solid polymer electrolyte membrane; a membrane electrode assembly; and a solid polymer fuel cell. A method for producing a fluorosulfonyl group-containing fluoropolymer according to the present invention is a production method in which monomer m1 (CF₂=CFCF₂O-Q¹-SO₂F) and TFE are copolymerized at a temperature of 150~200°C in the presence of a radical polymerization initiator in a reactor, wherein: the radical polymerization initiator is continuously or sequentially added into the reactor during copolymerization such that the concentration of the radical polymerization initiator in the reactor is maintained at 2.5 mass ppm or less of the mass of the monomer m1 charged in the reactor prior to the onset of copolymerization; and the molar ratio of the total amount of monomer m1 added to the total amount of TFE added is 1.5-20.