HYDROFLUORINATED OLEFINS (HFO'S) AS DILUENTS FOR BUTYL RUBBER PRODUCTION

摘要

A process for producing a copolymer involves contacting at least one isoolefin monomer with at least one multiolefin and/or β-pinene monomer in the presence of at least one Lewis acid and at least one initiator in a diluent. The diluent contains a hydrofluorinated olefin (HFO) comprising a tetrafluorinated propene. Copolymers produced by a process of the present invention have a cyclic oligomer content lower than comparable polymers produced in a butyl rubber slurry process using 1,1,1,2- tetrafluoroethane and/or methyl chloride as a diluent as well as a more favourable ratio of C21/C13. Hydrofluorinated olefins used in the present invention are better diluents for butyl slurry cationic polymerization than saturated hydrofluorocarbons.