| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for stably producing a propylene-based block copolymer exhibiting excellent flexibility, transparency, and low-temperature impact resistance, containing no gel or fish eyes, having no tackiness and good powder properties. Ž<P>SOLUTION: In a first process, using a metallocene catalyst, a propylene homopolymer component or a random copolymer component of propylene and another α-olefin is produced in an amount equivalent to 30-95 mass% of a propylene-based block copolymer by polymerization by a gas phase polymerization method. In a subsequent second process, a propylene-α-olefin copolymer component containing more α-olefin compared to that in the previous process is produced in an amount equivalent to 70-5 mass% of the propylene-based block copolymer by a gas phase polymerization method. In the method for continuously producing the propylene-based block copolymer via this multi-step polymerization method, at least one kind of compound (C) selected from methanol, ethanol and acetone is added in a polymer transfer section from the first process to the second process and/or in the second process. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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