GB813797A - Improvements in or relating to the polymerisation of ethylene - Google Patents

Abstract

Catalysts for use in polymerizing ethylene are obtained by heating aluminium with titanium tetrachloride in the absence of ethylene, other polymerizable hydrocarbons and organic compounds which would react with the catalysts or components thereof. Pure aluminium is preferably used, but alloys with copper, nickel and chromium are applicable. Catalyst preparation may be at temperatures up to 300 DEG C., optionally in the presence of mercuric chloride as activator, and desirable molar ratios of components are given. Hydrocarbon diluents which may be present during the catalyst preparation are hexane, heptane, decahydronaphthalene, cyclohexane, cyclohexene and benzene. Catalyst residues may subsequently be destroyed and/or removed with methanolic hydrochloric acid, methanol and/or solvents such as cyclohexane.ALSO:Polyethylene is obtained by batchwise or continuous polymerization of ethylene using a preformed catalyst made by heating aluminium with titanium tetrachloride in the absence of ethylene, other polymerizable hydrocarbons and organic compounds which would react with the catalyst or its components. The aluminium is preferably in the pure state, but alloys with copper, nickel and chromium may be used; technical grade ethylene may be polymerized. Catalyst preparation may be at temperatures up to 300 DEG C., optionally in the presence of mercuric chloride as activator, and various molar ratios of components are given. Hydrocarbon diluents, preferably purified (see Example V), may be present in the preparation in the catalyst and/or during the polymerization, and specified are hexane, heptane, decahydronaphthalene, cyclohexane, cyclohexene and benzene. The polymerization, which is desirably stopped when the concentration of polymer in diluent is between 10 and 45 per cent, may alternatively be in bulk (see Example VII). The solid, linear polymers obtained may be purified with methanolic hydrochloric acid, methanol, the use of solvents such as cyclohexane, or a combination of these methods. In examples, the intermittent addition of ethylene is described and it is stated that molten polymer may be drawn into translucent filaments (Example VI). The properties of a polymer containing carbon black and Sudan black are described.