PROCESS FOR PRODUCING FLUOROIONOMER, METHOD FOR PURIFICATION AND CONCENTRATION OF THE IONOMER, AND METHOD OF FILM FORMATION

摘要

A process for producing a fluoroionomer, characterized by copolymerizing (i) a compound represented by the following formula (I): (M)1/LOSO2CFY(CF2)mO(CFXCF2O)nCF=CF2 (wherein M is hydrogen or a metal having a valence of L (L is 1, 2, or 3); X is fluorine, chlorine, or CF3; Y is halogeno; m is 1 to 5; and n is 0 to 5), (ii) tetrafluoroethylene, and (iii) at least one third monomer selected from the group consisting of hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, CF2=CFORf(Rf is C1-5 perfluoroalkyl), and ethylene in the presence of a polymerization initiator. Also provided are a method for the purification/concentration of a fluoroionomer, characterized in that a fluoroionomer solution or dispersion is subjected to ultrafiltration or dialysis; and a method of forming a film of the fluoroionomer.