GB787375A - Improvements in or relating to the polymerisation or copolymerisation of ethylene - Google Patents

Abstract

Catalysts for the polymerization of ethylene (see Group IV (a)) comprise a halide of a Group IV (a), V (a) or VI (a) transition metal and an alkali metal in association or chemical combination with an acetylenic or ethylenic hydrocarbon in amount sufficient to reduce the valency of at least part of the transition metal to below 3. Specified catalyst components are titanium tetrachloride and tetrabromide, zirconium, tetrachloride, potassium, lithium, sodium, sodium acetylide and hydrocarbons such as propylene, butene, isobutylene, hexene, decene, butadiene, cyclohexene, substituted ethylenes, styrene, a -methyl styrene, stilbene, acetylene and phenyl acetylene. Catalyst complexes are said to be formed and the preferred molar ratios of the components used are given. The catalyst may be destroyed or removed with n-butanol or acetone/hydrochloric acid.ALSO:Ethylene is polymerized in the presence of a halide of a Group IV (a), V (a) or VI (a) metal and an alkali metal in association or chemical combination with an acetylenic or ethylenic hydrocarbon in amount sufficient to reduce the valency of at least part of the transition metal to below 3. Copolymers may also be obtained, e.g. with the unsaturated hydrocarbon used as activator, and specified hydrocarbons are propylene, butene, isobutylene, hexene, decene, butadiene, cyclohexene, substituted ethylenes, styrene, a -methyl styrene, stilbene, acetylene and substituted acetylenes such as phenyl acetylene. Transition metal halides used in the examples are titanium tetrachloride and tetrabromide and zirconium tetrachloride and the other catalyst component may be potassium, lithium or sodium, e.g. as the acetylide. An active complex is said to be formed and the preferred molar ratios of the components used are given. Polymerization may be carried out in bulk or in an inert liquid medium such as benzene, toluene or cyclohexene. In examples the process is carried out at ethylene pressures of 500 to 1000 p.s.i. Reaction may be stopped (Example (XV)) by the addition of n-butanol. The products are linear and of high density, and may be purified by treating with acetone, acetone/hydrochloric acid, acetone/sodium hydroxide and acetone/water. Films, wire insulation, fibres and filaments may be obtained.