Polymerisation process

Catalysts for use in the polymerization of olefins (see Group IV (a)) are formed by mixing a halide of titanium, zirconium or vanadium with a tin compound SnY4, Y3SnX or Y2XnX2, wherein X represents alkyl groups of not more than six carbon atoms and X represents halogen atoms. The catalyst may be preformed or formed in the presence of monomer, and preferred catalyst component molar ratios are given. Specified components are tin-tetraethyl-, tetraisopropyl- and triisopropyl-bromide, titanium-trichloride and tetrachloride and zirconium tetrachloride. Diluents which may be present are petroleum ether, pentane, hexane, cyclohexane, tetrahydronaphthalene, decahydronaphthalene, paraffins, benzene, xylene, dichlorobenzene, chlorinated naphthalene and mixtures thereof. After polymerization, catalyst residues may be removed from the products with methanol and/or methanolic hydrochloric acid.ALSO:Ethylene and/or a -olefins are polymerized by batchwise or continuous processes comprising contacting the monomers, in the absence of conjugated dienes, with a catalyst formed by mixing a halide of titanium, zirconium or vanadium with a tin compound SnY4, Y3SnX or Y2SnX2, wherein Y represents alkyl groups of not more than six carbon atoms and X represents halogen atoms. Specified olefins are propylene, butene, pentene and hexene and particular catalyst components disclosed are tin-tetraethyl, -tetraisopropyl and -triisopropyl bromide, titanium-trichloride and -tetrachloride, and zirconium tetrachloride. Catalyst may be preformed or formed in the presence of the monomer and preferred catalyst component molar ratios are given. The polymerization may be in bulk or in the presence of diluents such as petroleum ether, pentane, hexane, cyclohexane, tetrahydronaphthalene, decahydronaphthalene, paraffins, benzene, xylene, dichlorobenzene, chlorinated naphthalene and mixtures thereof, and these may also be present during the catalyst formation. Monomer may be added during the polymerization. The high molecular weight products obtained may be purified by treatment with methanol and/or methanolic hydrochloric acid.