METHOD OF PRODUCING PERFLUORINATED COPOLYMER WITH SULFOGROUPS Russian patent published in 2024 - IPC C08F14/18 C08F16/30 

FIELD: producing high-molecular compounds.

SUBSTANCE: invention relates to a method of producing a perfluorinated copolymer with sulfo groups by water-emulsion copolymerization of perfluoro-4-methyl-3,6-dioxaoct-7-ensulfonyl fluoride (SF) and tetrafluoroethylene (TFE). Polymerization is carried out in a steel reactor equipped with an overhead anchor mixer, in the presence of an initiator — a redox system — potassium persulfate — sodium metabisulfite and an emulsifier — a salt of perfluorononanoic acid. The process takes place at elevated temperatures (65–70°C) and pressure of 4.5–6 atm. Molar ratio of components in the polymerization system: perfluoro-4-methyl-3,6-dioxaoct-7-ensulfonyl fluoride: potassium persulfate: sodium metabisulfite: perfluorononanoic acid salt, equal to 1.000:1.092:(0.5–1.055):(25–40) respectively. Tetrafluoroethylene is fed into the reaction mixture containing perfluoro-4-methyl-3,6-dioxaoct-7-ensulfonyl fluoride, potassium persulfate, sodium metabisulfite and an emulsifier into the lower part of the reactor under the layer of the reaction mixture until a pressure of 6 atm is reached, then the resulting mixture is stirred at a speed of 1,000 rpm at a temperature of 70°C, after reducing the pressure in the reactor to~ 4.5 atm, a new portion of TFE is delivered until a pressure of 6 atm and a temperature of 65°C are reached with subsequent 4–5 repetitions of this cycle.

EFFECT: proposed method makes it possible to increase the yield of the target copolymer to 86% and the degree of sulfomonomer conversion to 95%, as well as to improve the quality of the copolymer due to the absence of reactive amide end groups in the resulting target product as a result of using an alkaline salt of perfluorononanoic acid as an emulsifier.

2 cl, 5 ex