POLYPROPYLENE BLOCK COPOLYMER, ITS USE, AND POLYPROPYLENE RESIN COMPOSITION COMPRISING SAID POLYPROPYLENE BLOCK COPOLYMER

摘要

Provided are a molding appearance modifier for resins capable of controlling appearance of large-sized molded parts only by small addition, and a polypropylene resin composition capable of providing good appearance to, for example, automobile exterior parts, and has excellent molding processability. The invention relates to a propylene block copolymer having a crystalline propylene polymer portion and a propylene·ethylene random copolymer portion, wherein the crystalline propylene polymer portion has an intrinsic viscosity [·] homo of 1.2 dl/g or less; the propylene·ethylene random copolymer portion has an ethylene content of 30 to 70 wt.%, has an intrinsic viscosity [·] copoly of 2.5 to 7.0 dl/g, and is added in an amount of 40 to 80 wt.% based on the whole propylene block copolymer; and the propylene block copolymer, in its entirety, has a melt flow rate of 0.1 to 10 g/10 min; and a [·] copoly / [·] homo ratio falls within a range of 2.5 to 10; and a polypropylene resin composition using the propylene block copolymer as a molding appearance modifier.