GB928933A - Process of preparing ethylene polymers - Google Patents

Abstract

Ethylene is polymerized in the presence of an inert liquid medium using a catalyst comprising both a titanium compound in which the titanium is in the tetravalent state and a compound comprising titanium in a valency state of less than 4, and formed by reaction in an inert liquid medium between titanium tetrahalide and a hydride, or organometallic compound of a metal of Groups I to III of the Periodic System, at least 50% of the total quantity of said reaction compound having been formed by a said reaction performed in the absence of the monomer to be polymerized and at least 70% of the total titanium of the catalyst present in the polymerization being in the tetravalent state. The preferred titanium tetrahalide is titanium tetrachloride. Specified hydrides and organometallic compounds are aluminium trialkyls, cadmium dialkyls, diethyl aluminium hydride, di-isobutyl aluminium hydride, diethyl aluminium chloride, di-isobutyl aluminium chloride and ethyl aluminium dichloride. Specified liquid media are saturated aliphatic hydrocarbons, methyl cyclopentane, aromatic hydrocarbons and halogenated hydrocarbons. The ethylene may be mixed with comonomers such as propylene or with hydrogen, nitrogen or saturated hydrocarbons. The polymerization may be effected continuously or batchwise, and the products treated in conventional ways, e.g. by treatment with methanol and water. Examples describe the polymerization of ethylene in the presence of catalysts formed from titanium tetrachloride and diethyl aluminium hydride or di-isobutyl aluminium hydride in saturated aliphatic hydrocarbon liquid media. Specification 918,642 is referred to.