| 摘要 |
PURPOSE:To obtain a polypropylene having excellent processability and high rigidity by polymerizing propylene in a multi-stage in the presence of a catalyst prepared by bringing a solid component containing Mg, Ti, a halogen and an electron donor, an organoaluminum compound and a specific Si compound to an olefin. CONSTITUTION:Propylene is polymerized in a multi-stage by using a polymerization catalyst prepared by bringing (A) a solid component containing Mg, Ti, a halogen and an electron donor as essential components into contact with (D) an olefin in the presence of (B) an organoaluminum compound and (C) an organosilicon compound of the formula [R<1> is Si-containing heterocyclic substituent group; R<2> is 1-10C hydrocarbon, R<4>O (R<4> is 3-10C hydrocarbon), R<5>3Si (R<5> is 1-10C hydrocarbon), etc.; R<3> is methyl or ethyl; (s) is 1 or 2; (y) is 0 or 1; z is 2 or 3; x+y+z=4] and a melt flow rate(MFR) of a polymer formed at each stage has 0.0001-10g/10 minutes at a stage of forming the highest molecular weight and 10-1,000g/10 minutes at a stage of forming the lowest molecular weight to give the objective polypropylene. |
