Process for the preparation of a catalyst-forming component suitable for polymerizing -‡-olefins to powders with improved properties

摘要

1,139,450. Catalyst. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 27 Dec., 1967, No. 58661/67. Heading C3P. In the polymerization ofα-olefins having up to six carbon atoms to polymer powders, preferably isotactic polypropylene, with improved bulk density and flow properties, a suitable catalyst component is formed by (1) mixing diethylaluminium monoohloride and titanium tetrachloride below - 5‹ C. in a molar ratio in the range of 0À5: 1 to 1À2: 1 in a paraffinic diluent, substantially free of oxygen, in a reaction vessel whose contents are stirred at a specific stirring power within the range of 50 to 2000 watt/m3 and (2) subsequently increasing the temperature of the mixture to at least + 15‹ C. whilst stirring with the above stirring power range at least as long as the temperature is below + 15‹ C. The temperature of the mixture may be increased from below -5‹ C. to within the range of 70‹ to 200‹ C. and subsequently lowered to ambient temperature below 70‹ C. whilst stirring is continued at a specific power not necessarily in the above range as soon as the temperature is above +15‹ C. Preferably, the reaction vessel is unbaffled and the contents of the vessel stirred with an agitator, such as a turbine stirrer, sweeping a volume of less than 10% of the internal vessel volume and rotating with a tip speed of more than 0.5 meter per second. Preferably, the TiCl 4 and AlEt 2 Cl are gradually mixed at a substantially constant temperature above -45‹ C. to attain the molar ratio of 0À5-1À2 in at least one hour but at most eight hours. The reaction vessel may be cooled to below - 5‹ C. before the aluminium or titanium compound is added. The stirring power may be kept within the range of 80 to 800 watt/m3 at least as long as the temperature is below + 15‹ C., and the power may be kept constant. The stirring conditions applied below +15‹ C. may be maintained in the region of +15‹ to +70‹ C., or may be increased in the region + 15‹ to + 45‹ C., and the mixture may be maintained in this latter temperature range for at least ¥ hr. During the reaction, monethyl aluminium chloride is formed, and this may be removed, or converted to diethylaluminium chloride or complex, with for example a Lewis base. A catalyst composition comprising at least two components may be formed by mixing TiCl 4 and AlEt 2 Cl at different specific mixing speeds. In the examples, a catalyst component was prepared by the above method and undesirable aluminium ethyl dichloride removed with dibutyl ether. The component was mixed with an activator comprising aluminium diethyl chloride and propylene was polymerized. The polymerization was terminated using nitrogen and a mixture of sec-butanol and hydrogen chloride, followed by steam distillation. The polymer was extracted with boiling diethy] ether.