Patent ID: 6313227
Filing Date: 2001-11-06
Classification: C08F,C08L

Abstract:
A propylene-ethylene block copolymer having a melt flow rate (MFR), measured at a temperature of 230.degree. C. and under a load of 2.16 kgf (21.2 N), of from 0.01 to 1.0 g/10 min, and comprised of (A) from 85 to 97% by weight a 25.degree. C. xylene-insoluble fraction and (B) from 3 to 15% by weight of a 25.degree. C. xylene-soluble fraction, wherein the fraction (A) is characterized in that (a-1) its stereospecificity index [mmmm] measured through isotopic carbon nuclear magnetic resonance (.sup.13 C-NMR) is at least 98.0%, (a-2) its intrinsic viscosity [.eta.] measured in tetralin at 135.degree. C. falls between 2.5 and 5.5 dl/g, and (a-3) its weight-average molecular weight, Mw, measured through gel permeation chromatography (GPC), and the content, S (% by weight), of the fraction having a molecular weight of at most 10.sup.4.5 therein satisfy the following formula (I):S.ltoreq.-5.3.times.10.sup.-6 Mw+7.58 (I)where Mw indicates the weight-average molecular weight of the fraction (A),and the fraction (B) is characterized in that (b-1) its ethylene unit content measured through .sup.13 C-NMR falls between 30 and 70% by weight, and (b-2) its intrinsic viscosity [.eta.] measured in tetralin at 135.degree. C. falls between 2.5 and 9.0 dl/g.