Method for producing stabilized fluoropolymer

1. A method for producing a stabilized fluoropolymer, comprising the step of

bringing a fluoropolymer to be treated into contact with a fluorinating agent in a stationary reactor to produce a stabilized fluoropolymer, while maintaining the concentration of hydrogen fluoride present in a reaction vessel at not higher than 1.0% by volume,

wherein the contacting step is carried out at a temperature of 50° C. or higher and 185° C. or lower, and

the fluoropolymer to be treated is in the form of a resin powder, a pellet, or a membrane obtained through molding, and

the fluoropolymer to be treated is constituted by 50 to 100 mol % of an ethylenic fluoromonomer unit and 0 to 50 mol % of a fluorinated alkyl vinyl ether unit, and

the fluoropolymer to be treated has an unstable group and

the unstable group is at least one group selected from the group consisting of —CF 2 COF, —CF 2 COOH, —CF 2 CH 2 OH, —CF 2 COOCH 3 , and —COOCO—, wherein —CF 2 COF —CF 2 COOH, —CF 2 CH 2 OH and —CF 2 COOCH 3 are terminal groups and wherein —COOCO— represents a group formed by bonding two —CF 2 COOH terminal groups.

2. The method for producing a stabilized fluoropolymer according to claim 1 ,

wherein the fluorinating agent is at least one substance selected from the group consisting of F 2 , NF 3 , SF 4 , ClF, ClF 3 , BrF 3 , and IF 5 .

3. The method for producing a stabilized fluoropolymer according to claim 1 ,

wherein the fluorinating agent is F 2 .

4. The method for producing a stabilized fluoropolymer according to claim 1 ,

wherein the contacting step is carried out at a temperature of 50° or higher and 120° or lower.