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.

A thin-film evaporator (TFE) includes a cylindrical body and blades disposed therein. However, to avoid clogging within a dead zone of a conventional discharge nozzle coupled to the cylindrical body of the TFE, an integrated drive screw apparatus intersects the cylindrical body of the TFE. The drive screw apparatus extracts processed material from the cylindrical body and ejects the processed material via a discharge nozzle coupled to the drive screw apparatus. The intersection of the cylindrical body of the TFE and the drive screw apparatus effectively reduces (possibly to zero) length of the dead zone.