PRODUCTION OF ION EXCHANGE MEMBER

PROBLEM TO BE SOLVED: To obtain an ion exchange membrane, excellent in durability against high temperatures, acids, alkalis, organic solvents, etc., and in mechanical strength by adhering a specific polymerizable composition to a polyolefin substrate exposed to the vapor of a polymerizable monomer, polymerizing the adhered monomers and, if necessary, subsequently introducing ion exchange groups to the adhered polymer. SOLUTION: This method for producing an ion exchange film comprises adhering (A) a polymerizable composition consisting mainly of (A1 ) a polymerizable monomer having an ion exchange group or a functional group into which the ion exchange group can be introduced [e.g. α-halogenated vinyl sulfonic acid, styrene sulfonic acid, (methyl)vinyl pyridine, vinyl pyrrolidone}], (A2 ) a crosslinking agent such as divinylbenzene or divinylpyridine, and (A3 ) a polymerization initiator to (B) a polyolefin substrate exposed to the vapor of a polymerizable monomer such as styrene or divinyl toluene, polymerizing the adhered monomers and subsequently introducing ion exchange groups into the adhered polymer.