| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyethylene composition more excellent in mechanical properties such as strength and rigidity and in molding properties and exhibiting improved practical properties such as gel and surface smoothness compared with conventional polyethylene compositions. SOLUTION: The polyethylene composition comprises at least two kinds of polyethylenes (A) and (B), where the polyethylene (A) is obtained by homopolymerization of ethylene or copolymerization of ethylene with a 3-20Cα-olefin using a catalyst carrying a chromium compound and the polyethylene (B) is obtained by homopolymerization of ethylene or copolymerization of ethylene with a 3-20Cα-olefin by a two-step polymerization using a titanium-based catalyst. In the first step, the lower-molecular weight portion having an MI of 10-300 g/10 min is manufactured, and in the second step the higher-molecular weight portion having an MI of 0.03-1 g/10 min in an amount 0.95-1.05 times the weight of the lower-molecular weight portion is manufactured. COPYRIGHT: (C)2004,JPO
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