GB834217A - Improvements in or relating to catalysts for the polymerisation of ethylene and ethylenic compounds - Google Patents

Abstract

Catalysts suitable for use in the Ziegler process as described in Specification 833,430 are prepared from two catalyst-forming components, one of which is a titanium compound, by forming one of the two components as a particulate solid having substantially the particle size required in the catalyst, suspending this component in an organic solvent, and adding the other component in a non-particulate condition to form the catalyst, the titanium compound, when particulate being an oxygen-containing organic compound. Preferably a major proportion of the catalyst has a particle size of 1 micron or less. Suspensions of catalyst forming components of reproducible particle size may be obtained by adding hydrocarbons to titanic esters of poly-alcohols, cellulose and polyglycols and derivatives of such esters and to concentrated solutions of calcium hydride or lithium aluminium hydride in an oxygenated organic solvent, e.g. diethyl ether. The titanium precipitates yield very effective catalysts on the addition of aluminium diethyl monochloride. Suitable catalyst component particles can also be obtained by adding aliphatic solvents to solutions of titanium tetraphenoxide and substitution derivatives thereof in aromatic solvents. In an example titanium tetrachloride is reacted with very small particles of filter paper to give a suspension of a mixture of esters of titanic acid and cellulose having a particle size less than 1 micron. The suspension is reacted with diethyl aluminium chloride to form a catalyst which is used for the polymerization of oxygen-free ethylene.ALSO:Olefins are polymerized using catalysts prepared from two catalyst-forming components, one of which is a titanium compound, by forming one of the two components as a particulate solid having substantially the particle size required in the catalyst, suspending this component in an organic solvent, and adding the other component in a non-particulate condition to form the catalyst, the titanium compound, when particulate being an oxygen-containing organic compound. Preferably, a major proportion of the catalyst has a particle size of 1 micron or less. Suspensions of catalyst forming components of reproducible particle size may be obtained by adding hydrocarbons to titanic esters of poly-alcohols, cellulose and polyglycols and derivatives of such esters and to concentrated solutions of calcium hydride or lithium aluminium hydride in an oxygenated organic solvent, e.g. diethyl ether. The titanium precipitates yield very effective catalysts on the addition of aluminium diethyl monochloride. Suitable catalyst component particles can also be obtained by adding aliphatic solvents to solutions of titanium tetraphenoxide and substitution derivatives thereof in aromatic solvents. In an example, titanium tetrachloride is reacted with very small particles of filter paper to give a suspension of a mixture of esters of titanic acid and cellulose having a particle size less than 1 micron. The suspension is reacted with diethyl aluminium chloride to form a catalyst which is used for the polymerization of oxygen-free ethylene. Specification 833,430 is referred to.