US Patent 9624329 Process for producing fluorinated copolymer

A process for producing a fluorinated copolymer includes polymerizing a fluorinated monomer having a carboxylic acid functional group or a sulfonic acid functional group and a fluorinated olefin by a solution polymerization method in a polymerization medium to obtain a mixture containing a fluorinated copolymer, an unreacted monomer and the polymerization medium. The mixture is continuously or intermittently transferred to an evaporation vessel provided with a stirrer and heating the mixture with stirring in the evaporation vessel to evaporate and recover the unreacted monomer and the polymerization medium.