HIGH-RIGIDITY ETHYLENE/PROPYLENE BLOCK COPOLYMER AND PROCESS FOR THE PRODUCTION THEREOF

摘要

A high-rigidity ethylene/propylene block copolymer composed of a crystalline polypropylene segment (I) and an ethylene/propylene random copolymer segment (II), wherein the segment (I) has a Q value (referring to a ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn)) of 5 on below as determined by gel permeation chromatography (GPC), an isotactic pentad fraction of 0.98 or above as calculated according to <13>C-NMR spectrometry, and an intrinsic viscosity of 0.6 to 0.88 dl/g as determined at 135 DEG C in tetralin, and the segment (II) has an intrinsic viscosity of 4.0 to 6.0 dl/g as determined at 135 DEG C in tetralin and an ethylene/propylene weight ratio of 25 : 75 to 35 : 65 and is contained in an amount of 8 to 22 wt.% based on the total amount of the segments (I) and (II); and a process for the production of the block copolymer.