Asahi Glass Company, Limited

Kaori Abe

Susumu Saito

Tetsuji Shimohira

Shigeru Aida

To provide a process by which from a mixture containing a fluorinated copolymer, an unreacted monomer and a polymerization medium, the unreacted monomer and the polymerization medium can efficiently be recovered, and a lower polymer contained in the obtainable fluorinated copolymer can readily be reduced. A process for producing a fluorinated copolymer comprising (I) a step of polymerizing a fluorinated monomer having a carboxylic acid functional group or a sulfonic acid fanctional group and a fluorinated olefin in a polymerization medium to obtain a mixture containing a fluorinated copolymer, the unreacted monomer and the polymerization medium, (II) a step of continuously or intermittently transferring the mixture to an evaporation container equipped with a stirring machine and heating the mixture in the evaporation container with stirring to evaporate and recover the unreacted monomer and the polymerization medium and to obtain the fluorinated copolymer, and (III) a step of washing the fluorinated copolymer with a washing medium.

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 tetrafluoroethylene by a solution polymerization method in a polymerization medium in the presence of a polymerization initiator to obtain a mixture. The mixture contains a fluorinated copolymer, an unreacted fluorinated monomer having the carboxylic acid functional group or the sulfonic acid functional group, and the polymerization medium. The mixture is continuously or intermittently transferred to an evaporation container equipped with a stirring machine and heated in the evaporation container with stirring to evaporate and recover a mixed liquid. The mixed liquid contains the unreacted fluorinated monomer and the polymerization medium with which the polymerization initiator is mixed. The recovered mixed liquid is heated to decompose the polymerization initiator.

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Kaori Abe