Process for polymerization of olefins
 A cocatalyst employed with a titanium-containing catalyst, said titanium-containing catalyst comprising titanium atoms, halogen atoms, and an electron donor compound, said cocatalyst comprising PA0 (a) an organoaluminum compound represented by the formula R.sup.1 R.sup.2 R.sup.3 (wherein R.sup.1, R.sup.2, and R.sup.3 which may be the same or different, each denote a C.sub.1-20 alkyl, alkenyl, cycloalkyl, aryl, aralkyl, or alkoxy group, or a hydrogen atom; PA0 (b) an organoaluminum compound represented by the formula R.sub.3-n.sup.4 AlX.sub.n (wherein R.sup.4 denotes a C.sub.1-20 alkyl, alkenyl, cycloalkyl, aryl, aralkyl, or alkoxy group; X denotes a halogen atom; and n.gtoreq.1), PA0 (c) an electron donor compound containing a nitrogen atom, sulfur atom, oxygen atom, or phosphorus atom, and PA0 (d) an aromatic carboxylic acid ester. The catalyst is useful for the polymerization of olefins. 
Toa Nenryo Kogyo Kabushiki Kaisha
C
C08F
inventional
Naomi Masami Makoto Masahito
Inaba Kizaki Miyazaki Fujita