METHOD OF PREPARING OF VINYLIDENE FLUORIDE WITH 5-12 MOL % OF HEXAFLUOROPROPYLENE Russian patent published in 2001 - IPC

FIELD: chemistry of polymers. SUBSTANCE: described is method of preparing vinyl fluoride copolymers with 5-12 mole % of hexafluoropropylene by aqueous emulsion copolymerization of said monomer at elevated temperature and pressure when reacted with organic peroxide in the presence of fluorine-containing surfactant using mixture of comonomers and adding this mixture of comonomers to reaction mixture. Formic acid is added to original aqueous emulsion reaction mixture in amount of 0.05-0.5% based on weight of water. Organic peroxide includes water-soluble organic peroxide, namely betaoxyethyl-tert butylperoxide in amount of 0.05-0.5% based on weight of water, and polymerization process is carried out at temperature of 85-95 and pressure of 2.0-2.2 MPa at initial pH value of 3.5-4.5 of reaction medium. Mixture of comonomers comprising vinylidene fluoride and hexafluoropropylene is used at molar ratio of (4:8):1, and feeding operation is carried out with mixture of comonomers which comprises vinylidene fluoride and hexafluoropropylene at molar ratio of (10-19):1. EFFECT: simplified process, higher thermal stability and color resistance of the desired copolymer. 10 ex, 2 tbl