| 摘要 |
PURPOSE:To provide a polymer composition for molding having a low mold shrinkage factor and excellent gloss, impact strength and rigidity, by mixing polypropylene, an ethylene-propylene-copolymer and polyethylene. CONSTITUTION:A polymer composition comprising 33-85wt% polypropylene having an isotacicity index of 90 or more (A), 0.6-9wt% ethylen-propylene copolymer containing 40-85mol% propylene unit (B), 0.6-31wt% polyethylene having an intrinsic viscosity of 0.5-3.0dl/g (C), and 10-40wt% ethylene-propylene copolymer containing 10-25mol% propylene unit (D). In the polymer composition, the four components are mixed so that propylene units have a ratio of 40-83mol% to the total monomer units of the polymer composition. Component polymers of (A), (B) and (C) are obtained by polymerizing olefins in advance in a polymerization reaction system in the presence of a stereoregular catalyst, and the component polymers are mechanically mixed with component (D) to provide the titled composition having the minimum mold shrinkage factor and good balance of impact strength and rigidity. |
