PROPYLENE BLOCK COPOLYMER, ITS PRODUCTION, AND ITS COMPOSITION

摘要

PURPOSE: To provide a propylene block copolymer excellent in stiffness, impact strength, heat resistance, and surface hardness. CONSTITUTION: The copolymer comprises 50-97wt.% polypropylene blocks which are homopolypropylene blocks or propylene-ethylene random copolymer blocks having an ethylene content of 2.0mol% or lower and 50-3wt.% copolymer blocks which are formed from propylene and ethylene and/or a 4-12Cα-olefin and satisfy all the following conditions: the average propylene contact (FP) as determined according to the two-site model is 20-80mol%; the propylene content (PP) of a copolymer (PH) produced at an active site where propylene is preferentially polymerized as determined according to the two-site model is 65-90mol%; the proportion (Pf1 ) of PH in the copolymer is 0.40-0.90; and the block characteristic (CSD) as determined according to the two-site model is 1.8-5.0.