METHOD FOR PRODUCING PERFLUORINATED COPOLYMER WITH SULFO GROUPS Russian patent published in 2023 - IPC C08F214/18 C08F214/26 B01F27/11 

FIELD: copolymers.

SUBSTANCE: present invention relates to a method for producing a perfluorinated copolymer with sulfo groups by water-emulsion copolymerization of perfluoro-4-methyl-3,6-dioxaoct-7-ensulfonyl fluoride and tetrafluoroethylene in a steel reactor equipped with an overhead stirrer with blades, in the presence of a redox initiator systems potassium persulfate - sodium metabisulfite and emulsifier - salts of perfluorononanoic acid at elevated temperature and pressure of 4.5-6 atm, characterized in that the copolymerization process is carried out in a steel reactor equipped with an overhead stirrer, having a wedge-shaped shape with evenly installed blades, the upper edge of which is located above the level of the reaction mixture, at a temperature of 65-70°C and the molar ratio of perfluoro-4-methyl-3,6-dioxaoct-7-ensulfonyl fluoride: potassium persulfate: sodium metabisulfite: perfluorononanoic acid salt equal to 1000:1.092:(0.5-1.055):(25-40), respectively, in this case, 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 the mixture is stirred at a speed of 1000 rpm at a temperature of 70°C, after reducing the pressure in the reactor to ~4.5 atm, a new portion of TFE is supplied until a pressure of 6 atm and a temperature of 65°C are reached with subsequent 4-5-fold repetition of this cycle.

EFFECT: increase in the yield of the target product to 94-96% and the degree of sulfomonomer conversion to 98%, as well as the quality of the copolymer due to the absence of reactive amide end groups in the resulting target copolymer.

2 cl, 1 dwg, 5 ex