METHOD FOR PREPARING COPOLYMERS OF TETRAFLUOROETHYLENE WITH HEXAFLUOROPROPYLENE Russian patent published in 2003 - IPC

FIELD: organic chemistry, polymers, chemical technology. SUBSTANCE: invention relates to method for preparing copolymers of tetrafluoroethylene with hexafluoropropylene. Method involves copolymerization of indicated monomers in mass of monomers or in medium of fluorine-containing ozone-safety solvent at temperature 25-50 C under pressure 1.1-1.5 MPa in the presence of perfluorinated initiating agent of radical type. Method involves the use of loading mixture of monomers comprising 80-86 mole % of hexafluoropropylene and 14-20 mole % of tetrafluoroethylene with feeding of reaction medium in the process of polymerization with mixture of monomers comprising 12- 15 mole % of hexafluoropropylene and 85-88 mole % of tetrafluoroethylene followed by removal of unreacted monomers and heating the prepared copolymer to remove residues of initiating agent. After termination of copolymerization process the reactive mass is cooled with pressure drop up to 0.3-1.0 MPa followed by its transfer by pressure into the closed volume under pressure by 0.05-0.1 MPa lower of pressure value in reaction zone. Then unreacted monomers are removed and solvent also, if necessary, in the closed volume at stirring with step-by-step rise of temperature firstly to 50-60 C up to pressure value 0.2-0.3 MPa and then to 120-200 C up to pressure 0.09-0.11 MPa with periodic pressure drop to the parent one at its rise by 0.1-0.12 MPa followed by heating the prepared powder of copolymer at temperature 120-200 C and under residual pressure 0.0026- -0.0052 MPa for 3-4 h. The claimed method ensures to prepare copolymers of tetrafluoroethylene with hexafluoropropylene of the broad assortment with good thermostability, high physical- mechanical properties with retention of high yield of ready product from unit of the reactor volume that provides high economical indices of process. EFFECT: improved preparing method, increased yield. 3 cl, 3 tbl, 5 ex