Method for producing .alpha.-olefin polymers

In the method for producing .alpha.-olefin polymers by polymerizing .alpha.-olefins in the presence of a catalyst, said catalyst being obtained by:

• (a) reacting one mol of anhydrous AlCl.sub.3 or anhydrous FeCl.sub.3 with 0.1 to 20 mols of a compound selected from the group consisting of Mg(OH).sub.2, MgO, Mg.sub.6 Al.sub.2 (OH).sub.16 CO.sub.3.4H.sub.2 O, MgCO.sub.3, MgAl.sub.2 O.sub.4 or 3MgCO.sub.3.Mg(OH).sub.2.H.sub.2 O;
• the reaction being carried out by milling and heating at a temperature between room temperature and 500.degree. C., to thereby produce a solid product (I);
• (b) reacting 1-5,000 g of at least one electron donor with 100 g of said solid product (I) in from one to ten steps in a suspension reaction manner or a milling reaction manner and at a temperature of between 0.degree. C. and 500.degree. C.,
• (c) reacting 1-5,000 g of at least one electron acceptor with 100 g of said solid product (I) in from one to ten steps, using TiCl.sub.4 as an electron acceptor in at least one step, in a suspension reaction manner or a milling reaction manner, and at a temperature of between 0.degree. C. and 500.degree. C.,
• these two kinds of reactions (b) and (c) being carried out separately or simultaneously together to thereby form a solid product (II),
• (d) forming catalyst components by combining said solid product (II) with an organoaluminum compound and an electron donor,
• said electron donors being selected from the group consisting of compounds having the general formula RCOOR', ROH, ROR', RCOR', and polysiloxanes characterized by the formula ##STR2## (wherein n=3 to 10,000 and R.sub.1 and R.sub.2 represent hydrogen or methyl and may be the same or different) and wherein in all of the foregoing formulas R and R' are alkyl or aryl groups having 1 to 20 carbon atoms,
• said electron acceptors being selected from the groups consisting of anhydrous SiCl.sub.4, SnCl.sub.2, SnCl.sub.4 and TiCl.sub.4,
• the improvement which comprises
• (1) carrying out a catalyst activation step by either
• (A) contacting an .alpha.-olefin with said solid product (II) and an organoaluminum compound at a temperature of 20.degree.-100.degree. C. under polymerizing conditions so as to thereby effect a preliminary polymerization, and then adding to this preliminary polymerization product one of the electron donors set forth above so that the total amounts of said organoaluminum compound, said electron donor and said .alpha.-olefin are 0.05 to 500 g, 0.05 to 20 g and 0.05 to 1,000 g respectively based on one gram of said solid product (II), or
• (B) contacting an .alpha.-olefin with said solid product (II), an organoaluminum compound and one of said electron donors at a temperature of 20.degree.-100.degree. C. under polymerizing conditions so as to thereby effect a preliminary polymerization and then adding to this preliminary polymerization product one of the electron donors set forth above so that the total amounts of said organoaluminum compound, said electron donor and said .alpha.-olefin are 0.05 to 500 g, 0.05 to 20 g and 0.05 to 1,000 g respectively based on one gram of said solid product (II), and
• (2) polymerizing .alpha.-olefins in the presence of the catalysts activated in accordance with step (1).