| 摘要 |
PROBLEM TO BE SOLVED: To obtain a block propylene copolymer having improved impact resistance by continuously polymerizing propylene, transferring the reaction mixture to another polymerizer without deactivating the contained catalyst, and copolymerizing an elastomer component in the polymerizer under specified conditions of polymerization activity. SOLUTION: This production process comprises step 1 of continuously polymerizing anα-olefin mixture based on propylene, step 2 of transferring the reaction mixture to a separate polymerizer without deactivating the contained catalyst, continuously copolymerizing propylene with anα-olefin in a substantially vaporous phase under conditions in which the polymerization activity K of an elastomer component, as defined by formula I [wherein K (θ) is the yield (g) of an elastomer per g of the catalyst, atm. of monomer pressure and unit time;θis the average residence time (hr) in the elastomer polymerizer; K (1/hr) is a constant representing the constant of catalyst deactivation; A (g/g (CAT.hr.atm) is the activity constant of the solid catalyst component; and K (1) is the value of K (θ) atθ=1], and melt-kneading the obtained product to obtain a low-fisheye propylene block copolymer having an elastomer component content of 5-60wt.%.
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