Abstract: A catalyst for the polymerization of olefins comprising:(A) a catalyst component obtained by a process comprising contacting (a) a fatty acid salt of magnesium, (b) a carbonate of magnesium or a substance containing said carbonate, (c) diester of an aromatic dicarboxylic acid, and (d) a titanium halide of the general formula: TiX.sub.4, wherein X represents a halogen atom;(B) a silicon compound represented by the general formula: SiR.sub.m (OR').sub.4-m, wherein R is hydrogen, alkyl group or aryl group, R' is alkyl group or aryl group, and m is represented as O.ltoreq.m.ltoreq.4; and(C) an organoaluminium compound.Polymerization of olefins by use of the catalyst provides such advantages as high polymerization activity per unit weight of the catalyst component, prolonged polymerization activity, high yield of stereoregular polymer, and a produced polymer free of such an estereal odor as in the prior art, and having high bulk density as well as uniform particle size and shape.

Abstract: A process for the preparation of the former catalyst component of a catalyst for the polymerization of olefins composed of a titanium-based catalyst component and an organo aluminium compound is disclosed, which process comprises suspending (a) a fatty acid salt of magnesium and (b) dialkoxymagnesium into (c) a liquid halogenated hydrocarbon to form a first suspension, and adding said first suspension to (d) a titanium halide of the general formula: TiX.sub.

Abstract: A process for the preparation of the former catalyst component of a catalyst for the polymerization of olefins composed of a titanium-based catalyst component and an organo aluminium compound is disclosed.The former catalyst component can readily be produced by contacting (a) a fatty acid salt of magnesium, (b) an electron donor compound and (c) a titanium halide.In the polymerization of olefins by use of the former catalyst component, both the amount of catalyst residues in the produced polymer and halogen content therein are greatly reduced with high polymerization activity per unit weight of the former catalyst component and with high yield of stereoregular polymer.

Abstract: Disclosed is a process for the preparation of the former catalyst component of a catalyst for the polymerization of .alpha.-olefins composed of a titanium-based catalyst component and an organo aluminium compound. According to the above process, a magnesium halide is copulverized with aluminium isopropoxide to form a first copulverization product, to which an electron donor compound is added for copulverization to form a second copulverization product, and the second copulverization product is brought into contact with a titanium halide followed by washing with an inert organic solvent.In the polymerization of .alpha.-olefins by use of the former catalyst component as above, both polymerization activity per unit weight of the catalyst component and yield of stereoregular polymers are remarkably increased.