GB1059865A - Ethylene polymerisation and copolymerisation - Google Patents

Abstract

Ethylene polymers are made by polymerizing ethylene alone or together with one or more olefin monomers, e.g. propylene, at a temperature of at least 50 DEG C. and in a liquid reaction medium comprising a hydrocarbon and a catalyst formed by mixing a compound of a metal of Group V(a), or VI(a) of the Periodic Classification and an organometallic compound of a metal of Group I(a), II(a) or III(b) of the Periodic Classification, and a poly-halo organo-halogen compound, and the amount of catalyst in the reaction mixture is controlled in such a manner that the Group V(a) or VI(a) metal concentration therein is maintained below 0.1 milliatom per litre thereof and the total amount of organometallic compound or compounds supplied to the reaction mixture being such that a substantially steady rate of polymerization is maintained. The poly - halo organo - halogen compounds used are those organic halogen compounds containing in their molecular structures a grouping -CX3, in which each X represents a flourine, chlorine, or bromine atom, and said grouping is attached either to an atom or group more electronegative than hydrogen (e.g. a halogen atom) or to a hydrogen atom. Specified compounds are CCl4, CBr4, C2Cl6, CHCl3, and CHBr3. Preferred compounds of Groups V(a), and VI(a) are vanadium tris(acetylacetonate), vanadium oxybis(acetylacetonate), VO(OBu)3, vanadium di-isopropyl salicylate, vanadium naphthenate, and the corresponding chromium compounds. The preferred organometallic compounds are organoaluminium compounds. The catalyst may be preformed or formed in situ.