GB827462A - Polymerisation process - Google Patents

Abstract

Catalysts for the polymerization of ethylene (see Group IV (a)) are obtained by mixing lithium aluminium tetrahydride with titanium, zirconium or vanadium halides, e.g. the tri- and tetra-chlorides. An inert medium, such as petroleum ether, is preferably used in the preparation of catalyst and in the subsequent polymerization. Catalyst residues may be removed from the polymer obtained, by treatment with methanolic hydrochloric acid followed by methanol alone. In the Provisional Specifications the Ti, Zr or V compound may be an oxychloride, a complex fluoride, an oxide or hydroxide, or an acetate, alcoholate, benzoate or acetyl acetonate. Specification 827,464 is referred to.ALSO:Ethylene is polymerized with a catalyst formed by mixing lithium aluminium tetrahydride with a titanium, zirconium or vanadium halide, e.g. a tri- or tetrachloride. The catalyst components may be admixed first or only in the presence of ethylene, and preferred molar ratios are specified. An inert solvent is preferably included and disclosed are petroleum ether, pentane, hexane, cyclohexane, tetrahydronaphthalene, decahydronaphthalene, higher paraffins, benzene, xylene, dichlorobenzene, chlorinated naphthalene, or mixtures thereof. Polymerization may be batchwise or continuous and in examples ethylene is admitted throughout the reaction. Catalyst may be destroyed and the product purified by treatment with methanolic hydrochloric acid followed by methanol. Tough polyethylene film is obtained on pressing. In the Provisional Specifications the Ti, Zr or V compound may be an oxychloride, a complex fluoride, an oxide or hydroxide, or an alcoholate, acetate, benzoate or acetyl acetonate. Specification 827,464 is referred to.