Process for producing fluorinated copolymer
View Patent ↗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.
1. A process for producing a fluorinated copolymer, the process comprising:
(I) 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 slurry containing a fluorinated copolymer, an unreacted monomer and the polymerization medium;
(II) continuously or intermittently transferring the slurry to an evaporation vessel provided with a stirrer and heating the slurry with stirring in the evaporation vessel under a pressure below atmospheric pressure to evaporate and recover the unreacted monomer and the polymerization medium, while keeping the fluorinated copolymer in the evaporation vessel; and
(III) taking out the fluorinated copolymer from the evaporation vessel after finishing the recovery of the unreacted monomer and the polymerization medium,
wherein a stirring blade in the evaporation vessel is a scraping blade which rubs against a wall surface of the evaporation vessel when rotating.
2. The process for producing a fluorinated copolymer according to claim 1 , wherein the fluorinated monomer having a sulfonic acid functional group is a compound represented by the following formula (2) or (3):
CF 2 ═CF—O—R f2 -A 2 (2)
CF 2 ═CF—R f2 -A 2 (3)
wherein R f2 is a C 1-20 perfluoroalkylene group, which may contain an etheric oxygen atom, and which may be linear or branched, and A 2 is a sulfonic acid functional group.
3. The process for producing a fluorinated copolymer according to claim 1 , wherein a stirring blade in the evaporation vessel is a helical ribbon blade.
4. The process for producing a fluorinated copolymer according to claim 1 , wherein in the step (II), the slurry is transferred to the evaporation vessel so that the overall coefficient of heat transfer becomes at least 80 kJ/m 2 ·h·° C.
5. The process for producing a fluorinated copolymer according to claim 1 , wherein the amount of the unreacted monomer remaining is at most 1.0 mass % per 100 mass % of the fluorinated copolymer.
6. A process for producing a fluorinated copolymer, the process comprising:
(I′) polymerizing a fluorinated monomer having a carboxylic acid functional group or a sulfonic acid functional group and a fluorinated olefin by a bulk polymerization method to obtain slurry containing a fluorinated copolymer and an unreacted monomer;
(II′) after the polymerizing of the fluorinated monomer and the fluorinated olefin is completed, continuously or intermittently transferring the slurry to an evaporation vessel provided with a stirrer and heating the slurry with stirring in the evaporation vessel under a pressure below atmospheric pressure to evaporate and recover the unreacted monomer, while keeping the fluorinated copolymer in the evaporation vessel; and
(III′) taking out the fluorinated copolymer from the evaporation vessel after finishing the recovery of the unreacted monomer,
wherein a stirring blade in the evaporation vessel is a scraping blade which rubs against a wall surface of the evaporation vessel when rotating.
7. The process for producing a fluorinated copolymer according to claim 6 , wherein the fluorinated monomer having a sulfonic acid functional group is a compound represented by the following formula (2) or (3):
CF 2 ═CF—O—R f2 -A 2 (2)
CF 2 ═CF—R f2 -A 2 (3)
wherein R f2 is a C 1-20 perfluoroalkylene group, which may contain an etheric oxygen atom, and which may be linear or branched, and A 2 is a sulfonic acid functional group.
8. The process for producing a fluorinated copolymer according to claim 6 , wherein a stirring blade in the evaporation vessel is a helical ribbon blade.
9. The process for producing a fluorinated copolymer according to claim 6 , wherein in the step (II′), the slurry is transferred to the evaporation vessel so that the overall coefficient of heat transfer becomes at least 80 kJ/m 2 ·h·° C.
10. The process for producing a fluorinated copolymer according to claim 6 , wherein the amount of the unreacted monomer remaining is at most 1.0 mass % per 100 mass % of the fluorinated copolymer.