Abstract: 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.

Abstract: Propylene is polymerized in the presence of a catalytic system of the type which comprises a solid titanium trichloride-based complex serving as a catalyst, said complex having an atomic ratio of aluminum to titanium in the range of below 0.15:1 and containing a complexing agent, and an organic aluminum compound of the general formula, AlR.sup.1.sub.n Cl.sub.3-n wherein R.sup.1 represents an n-propyl group or an n-hexyl group and n is a value of 1.95-2.10. The catalytic system may further comprise an electron-donor compound as a third catalytic component.

Abstract: Propylene is polymerized in the presence of a catalytic system of the type which comprises a solid titanium trichloride-based complex serving as a catalyst, said complex having an atomic ratio of aluminum to titanium in the range of below 0.15:1 and containing a complexing agent, and an organic aluminium compound of the general formula, AlR.sub.n.sup.1 Cl.sub.3-n wherein R.sup.1 represents an n-propyl group or an n-hexyl group and n is a value of 1.95-2.10. The catalytic system may further comprise an electron-donor compound as a third catalytic component.

Abstract: In a process for preparing polyolefin by polymerizing an olefin in the presence of a catalyst system combining an organoaluminum compound and a titanium-containing solid catalytic component prepared by mixing (a) water and/or a hydroxy 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.

Abstract: A process for producing stabilized polyolefins comprising adding an epoxide to a polyolefin slurry obtained through polymerization of .alpha.-olefins in the presence of a catalyst containing a halide of a transition metal and an organoaluminum compound to render the catalyst remaining in the polymer inactive, and then subjecting the polyolefin slurry after the above inactivation treatment to an evaporation treatment. The process is extremely simple and results in polyolefins and molded products which are highly stable against discoloration and heat.

Abstract: Solid titanium trichloride in the form of fine granules having low aluminum compound content, which is suitable as a catalyst for polymerization of .alpha.-olefins, especially, propylene is obtained as a precipitate by heating liquefied titanium trichloride in the presence of a liberating agent, and separating the thus formed precipitate. The liquefied titanium trichloride is preferably prepared with an reducing titanium tetrachloride by organic aluminium compound in the presence of ether and hydrocarbon.

Abstract: Solid titanium trichloride in the form of fine granules having low aluminum compound content, which is suitable as a catalyst for polymerization of .alpha.-olefins, especially, propylene is obtained as a precipitate by heating liquefied titanium trichloride in the presence of a liberating agent, and separating the thus formed precipitate. The liquified titanium trichloride is preferably prepared with an reducing titanium tetrachloride by organic aluminum compound in the presence of ether and hydrocarbon.