| 摘要 |
The present invention provides olefin polymerization catalysts and processes for preparing a polypropylene and propylene block copolymer using said olefin polymerization catalysts. The olefin polymerization catalyst (1) of the invention is formed from: ¢I-1! a contact product obtained by contacting: (A) a solid titanium catalyst component, (B) an organometallic compound catalyst component, and (C) a specific organosilicon compound; ¢II-1! (D) a specific polyether compound; and optionally, ¢III! an organometallic compound catalyst component The olefin polymerization catalyst (2) of the invention is formed from: ¢I-2! a contact product obtained by contacting: (A) a solid titanium catalyst component, (B) an organometallic compound catalyst component, and (D) a specific polyether compound; ¢II-2! (C) a specific organosilicon compound; and optionally, ¢III! an organometallic compound catalyst component. The contact product ¢I-1! or ¢I-2! may be replaced by one which is obtained by prepolymerizing an olefin of 2 or more carbon atoms in the presence of the catalyst components for the contact product ¢I-1! or ¢I-2! in such a way that the amount of the prepolymer formed is 0.01 to 2,000 g based on 1 g of the solid titanium catalyst component (A). In the processes for preparing a polypropylene according to the invention, propylene is polymerized in the presence of the above-mentioned olefin polymerization catalysts. According to the invention, highly isotactic polypropylene can be prepared. The processes for preparing a propylene block copolymer according to the invention comprises the steps of polymerizing propylene to form a polypropylene component and copolymerizing ethylene and an .alpha.-olefin of 3 to 20 carbon atoms to form an ethylene/.alpha.-olefin copolymer component, in an optional order, in the presence of the specific polymerization catalysts. In the propylene block copolymer obtained by the invention, the polypropylene component is highly isotactic and the rubber component has a high intrinsic viscosity ¢n!. |
