GB923840A - Polymerization of diene polymers - Google Patents

Abstract

Polymers of conjugated dienes are made by polymerizing a diene in the presence of a catalyst comprising an organometallic compound, to give a controlled molecular weight product, by charging initially only a portion of the total monomer to a polymerization zone together with the catalyst, allowing the polymerization to proceed to at least a 50% conversion, then charging the remainder of the monomer into the zone in at least one additional increment and continuing the polymerization, until a polymer of the desired molecular weight is obtained. The polymerization is generally effected in the presence of an inert diluent. Specified dienes are 1,3-butadiene, 2-methyl-1, 3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 2,3-dimethyl-1, 3-pentadiene, 3-methyl-1,3-pentadiene, and 2 phenylbutadiene. The dienes may be polymerized alone or in admixture with each other and/or with mono-ethylenically unsaturated compounds such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, isobutylene, butene-2, pentene-2, hexene-2, heptene-2, 2-methyl-butene-1, 2-methylhexene-1, 2-methylheptene-1, non-conjugated dienes, cyclohexene, styrene, acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, 5-methyl-2-vinylpyridine, 2-vinyl pyridine, 4-methylpyridine, 3-vinyl-toluene, 1-vinyl-naphthalene, 2-vinylnaphthalene, or 4-vinyltoluene. The catalysts are of the conventional "low-pressure" types. The preferred catalyst system comprises (a) an organometallic aluminium compound and (b) titanium tetraiodide, or titanium tetraiodide plus the tetrachloride, or titanium tetrachloride plus iodine. The process may be effected batchwise or continuously. The polymer may be vulcanized and made into tyres and gaskets.