GB993485A - Conjugated diene polymers - Google Patents

Abstract

Rubbery polymers are made by polymerizing a C4 to C10 conjugated diene alone or in admixture with another monomer in the presence of an organometallic or metal hydride catalyst and controlling the molecular weight of the product by charging initially to the polymerization zone only a portion of the total monomers to be used togehter with the initiator, allowing polymerization of this initial charge to proceed until 20 to 50% conversion has been attained, then charging the remainder of the monomeric material in at least one additional increment, and continuing the polymerization until a polymer of the desired molecular weight is obtained. The polymerization is preferably effected in a hydrocarbon diluent. The conjugated diene may be butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-, 2,3-dimethyl-, or 3-methyl-1,3-pentadiene, or 2-phenylbutadiene. The other monomer may be ethylene, propylene, 1-butene, 1-hexene, 1-octene, isobutylene, 2-olefines, di-non-conjugated- or multi-olefines, cyclohexene, styrene, acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, 5-methyl-2-vinylpyridine, 2-vinylpyridine, 4-vinylpyridine, 3-vinyltoluene, 1-vinylnaphthalene, 2-vinylnaphthalene, or 4-vinyltoluene. The Specification contains a long list of suitable catalysts for making cis- or trans-polymers. Preferred catalysts are formed by mixing an organo-aluminium compound, e.g. triisobutyl-aluminium, with TiI4, TiI4+TiCl4, or TiCl4+I2. The polymers are recovered by known techniques, e.g. addition of methanol.