GB589353A - Process for the production of rubber-like polymers - Google Patents

Abstract

In the low temperature polymerization of iso-olefines having up to 8 carbon atoms with or without a minor proportion of a diolefine having up to 14 carbon atoms, in an alkyl halide diluent having less than 5 carbon atoms at temperatures below -40 DEG C. in the presence of a Friedel-Crafts catalyst dissolved in the same alkyl halide, the reaction slurry is passed into warm water in a flasking zone and its volatile components vaporized and withdrawn, cooled, compressed and dried. The volatile components are then fractionated to give substantially pure alkyl halide (which is used for the preparation of catalyst solution), a mixture of iso-olefine and alkyl halide which is recycled to the feed, and a residue of hydrocarbon by-products which is discarded. The residue may be further fractionated to separate any unreacted diolefine present which is recycled to the feed. Where the alkyl halide is very volatile, e.g. methyl chloride, the pure halide is withdrawn in a first distillation and the mixture of alkyl halide and iso-olefine distilled from the residue, but where a less volatile halide is used, e.g. ethyl chloride, the mixture is removed first and pure alkyl halide distilled from the residue. The alkyl halide recovered may be purified by scrubbing with sulphuric acid, passed over dry caustic soda and redistilled before using to prepare catalyst solution. Isobutylene is the preferred iso-olefine and diolefines specified include butadiene, isoprene, dimethyl butadiene, piperylene, myrcene and dimethylallene. Isobutylene for the feed may be distilled twice, first to remove water and again to remove isobutane, normal butylenes and C5 and heavier hydrocarbons. The diolefine used may be first purified by washing with water and distilled after addition of inhibitor, e.g. tert-butyl catechol or hydroquinone. Specifications 432,196, 483,453, 561,324 and 565,974 are referred to.