GB866679A - Process for the manufacture of high molecular polyethylene - Google Patents

Abstract

Ethylene is polymerized in a low pressure polymerization process by introducing into a reaction vessel containing in an inert solvent a compound of a metal of Group 4a, 5a or 6a, the metal in this compound having a valency lower than its maximum valency and before or at the start of the polymerization adding a mixture of a methyl-aluminium organic compound and a compound of a metal of Group 4a, 5a or 6a, the metal in this compound having the maximum valency. The mixture of catalyst compounds may be added gradually or continuously to the polymerization batch, while the compound of a metal of lower valency may be prepared in a separate process by reduction of a compound containing the metal in its maximum valency. The catalyst mixture may be of a methyl-aluminium compound and a compound of tetravalent titanium, e.g. dimethyl aluminium monochloride titanium tetrachloride. The ethylene may be first introduced into a catalyst mixture of the methyl-aluminium compound, a tetravalent titanium compound and a trivalent titanium compound, and a catalyst mixture of a methyl-aluminium compound and a compound of tetravalent titanium added later. Specifications 799,392, 799,823, 801,031, 828,201 and 828,692 are referred to.