Mitsubishi Chemical Industries Limited

Kazuhisa Kojima

Yoshinori Suga

Masayoshi Hasuo

Masatoshi Suzuki

Genjiro Kakogawa

Yoshiteru Kobayashi

In a process for preparing polyolefin by polymerizing an olefin in the presence of a catalyst system combining an organo-aluminum compound and a titanium containing solid catalytic component prepared by mixing (a) a silanol compound (b) a Grignard reagent and (c) a titanium tetrahalide, the components (a) (b) or (c) or the reaction mixture of two or three components thereof is contacted with (d) one or more electron donor selected from the group consisting of amines, carboxylic acid amides, phosphines, phosphine oxides, phosphoric esters, phosphorous esters, phosphoric acid amides, ketones and carboxylic esters. The polyolefin having high isotactic index can be obtained.

Process for preparing polyolefin

A propylene-ethylene block copolymer is produced in the presence of a catalytic system essentially comprising an organoaluminum compound and a solid titanium trichloride catalytic complex having an atomic ratio of Al to Ti of less than 0.15 and having a complexing agent in two stages of polymerization;

Process for producing propylene-ethylene block copolymer

A fine solid titanium trichloride is used as a catalyst for a polymerization of an .alpha.-olefin. The solid titanium trichloride is produced by precipitating it at lower than 150.degree. C. from a liquid titanium trichloride complex in the presence of an ester having the formula ##STR1## wherein R.sup.1 and R.sup.2 respectively represent a hydrocarbon moiety and total carbon atoms of R.sup.1 and R.sup.2 are 10 or more.

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Yokohama, Japan

Kazuhisa Kojima