OLEFIN POLYMERIZATION CATALYST AND METHOD OF POLYMERIZATION OF ETHYLENE Russian patent published in 1998 - IPC

FIELD: synthesis of ethylene copolymers. SUBSTANCE: ethylene copolymerization is carried out in the presence of catalyst consisting of at least two catalytic chromium systems. At least one system comprises at least 80 wt % silicon dioxide and at least 0.1 wt % titanium dioxide and having mean pore radius of 28-85 $$$ and pore volume of 0.6-1.2 cubic cm/g. This catalytic system is activated at 450-900 C followed by reduction. At least one other catalytic system comprises carrier consisting substantially from silicon dioxide and having mean pore diameter of 1.5-4.0 cubic cm/g. This catalytic system is reduced followed by reduction. Catalytic chromium systems comprise one or more chromium compounds selected from group comprising chromium nitrate, chromium acetate, chromium trioxide, and mixture thereof composed of two or more compounds. Properties of the resulting copolymers have improved density, chemoresistance, tensile strength, impact viscosity and cracking resistance due to addition of nonethylenic copolymer to higher molecular weight portion of copolymer. EFFECT: improved properties of the catalyst. 8 cl, 2 tbl