Patent GB-909063-A (GB)
IPC: C08F10/00
Abstract: 909,063. Titanium trichloride. STANICARBON N.V. Feb. 4, 1959 [Feb. 6, 1958; Oct. 20, 1958], No. 3986/59. Class 1(3) [Also in Group IV(a)] The titanium trichloride component of a catalyst employed for polymerization of alpha olefinic hydrocarbons containing at least 3 carbon atoms, is prepared by reducing titanium tetrachloride with a hydride or organo metallic compound of a metal of Group I to III of the Periodic system, at 15‹ to 20‹C. and thereafter heating the resulting titanium trichloride containing mass, during or after at least partial removal of the chlorinated reducing agent, to a temperature from 200‹-350‹C. The stereospecificity of the catalyt is thereby improved. The polymerization catalyst consists of the titanium trichloride compound as above prepared, together with a tri-alkyl aluminium compound such as tri-ethyl, tri-propyl, dimethyl ethyl, diethyl isobutyl, tri-hexyl aluminium or an alkyl aluminium hydride such as diethyl aluminium hydride or di-isobutyl aluminium hydride. The two catalyst components may be brought together before the polymerization or separately and continuously added, preferably in ratios such that the Al :Ti ratio is greater than 1. The reduction of the titanium tetrachloride may be effected in an inert diluent such as saturated hydrocarbons, for example, hexane, heptane or cyclohexane, or gasoline, kerosene, benzene, toluene or haologenated hydrocarbons such as chlorobenzene. The reduction may be promoted by the addition of ethanol or butanol. Particularly suitable Group I to III metal reducing agents are diethyl aluminium hydride di-isobutyl aluminium chloride, triethyl-, trimethyl-, triphenyl-aluminium, diethyl aluminium chloride, methyl aluminium dichloride, diphenyl aluminium chloride, ditolyl aluminium bromide and ethyl aluminium sesquichloride or sesquibromide. Other reducing compounds may be sodium hydrides, cesium hydrides, dimethyl magnesium, diethyl cadmium, dipropyl zinc, dihexyl zinc, methyl sodium and diphenyl cadmium. The bi-products of the reaction are preferably removed from the titanium tetrachloride by distillation in the presence of a liquid with an atmospheric boiling point above 180‹C. Such liquid may be present initially or may be added after reductionbut prior to distillation. Distillation may be effected in vacuuo and the required heating at 200‹-350‹C. effected as a subsequent step, or the heating and distillation may be simultaneous. Alternatively the titanium trichloride may be separated from the chlorinated reducing compound and exposed to dry heating in the absence of moisture and oxidizing gases. According to Examples (1) a solution of titanium tetrachloride in heptane was mixed at room temperature with a solution of tri-isobutyl aluminium in heptane and after the resulting precipitate had settled the liquid was removed by decantation. The precipitated titanium trichloride was washed in heptane and heated at 250‹C. for 30 minutes, in an argon atmosphere, and kept for 30 minutes, in an argon atmosphere, and kept in this atmosphere or suspended in heptane until required for polymerization. Propylene polymerization was effected in a rocking autoclave to which titanium trichloride prepared as above, triethyl aluminium and dry heptane were added simultaneously after which oxygen-free propylene was fed whilst the temperature was maintained at 70‹C. and at pressure at 2À5 atmosphere. The resulting polymer suspension was diluted with heptane and the catalyst decomposed by adding butanol and stirring at 80‹-90‹C. The polymer was then washed with a mixture of methanol and water, filtered and dried thereby obtaining polypropylene containing 95 % crystalline polymer. The amorphous polypropylene was extracted by diethyl ether at 30‹-35‹C. and hexane at 65‹C. (4) A solution of titanium tetrachloride in heptane and a separate solution of di-isobutyl aluminium hydride in heptane was continuously fed as separate streams to a stirring vessel whilst maintaining the Al/Ti ratio at unity. The reaction vessel was maintained at 15‹-20‹C. and the titanium trichloride suspension was withdrawn and separated in a nitrogen atmosphere and heated at 300‹C. (5) A solution of triethyl aluminium in a hydrocarbon fraction (B.P. 175 to 50‹C.) was slowly added to a solution of titanium chloride in the same solvent at room temperature. After 3 hours the temperature was raised 200‹-225‹C. whereupon the byproducts and part of the hydrocarbon fraction distilled off. The polymerization catalyst is thereafter prepared by adding di-isobutyl aluminium hydride to the titanium trichloride suspension thus treated.