POLYPROPYLENE BLOCK COPOLYMER COMPOSITION HAVING IMPROVED HEAT RESISTANCE, IMPACT STRENGTH, AND ORANGE PEEL

摘要

A polypropylene block copolymer resin composition is provided to realize excellent low-temperature impact resistance, orange peel characteristics, heat resistance, peel strength and appearance suitable for a food packaging film. A polypropylene block copolymer resin composition comprises: (A) 83-97 parts by weight of a crystalline polypropylene block copolymer containing 85-99.5 parts by weight of propylene and 0.5-15 parts by weight of ethylene; and 3-17 parts by weight of at least one polymer selected from (B) an amorphous or crystalline ethylene-1-butene random copolymer, (C) an amorphous or low-crystalline propylene-ethylene random copolymer and (D) a polybutene-1 polymer. The crystalline polypropylene block copolymer is obtained by polymerizing propylene in a first reactor and by copolymerizing ethylene therewith in a second reactor, contains a polypropylene segment and an ethylene-propylene rubber segment, and has a melting point of 150-165 deg.C and a melt index (ASTM D1238) of 1-5g/10 min (230 deg.C, 2.16 kg).