| abstract |
An olefin polymerization catalyst composition comprising: n (a) a reaction product of an organo aluminium compound and an electron donor, and n (b) a product obtained by contacting a solid component comprising a magnesium halide in which the atomic ratio of chlorine to magnesium is at least 1.2, a titanium halide and an electron donor, with a halohydrocarbon and with a tetravalent titanium compound. |