Patent ID: 6201069
Filing Date: 2001-03-13
Classification: C08F,C08L

Abstract:
A polypropylene/propylene-ethylene copolymer composition having a melt flow rate (ASTM D-1238; the same applies hereinafter) of from 1 to 80 g/10 min obtained through:a first stage (polymerization step (I)) in which propylene is polymerized in the presence of a highly stereoregular catalyst and hydrogen to produce a propylene polymer having a melt flow rate in the range of from 15 to 99 g/10 min and a tie molecule volume content (.beta.), as obtained from an oriented sample and defined by.beta.=(1-0.01Xc)E/(41-0.01Xc.multidot.E)wherein Xc: degree of crystallization (%); andE (GPa): modulus of elasticity, of 1.38% or higher in an amount of from 60 to 95% by weight based on the total amount of the composition to be finally obtained; anda second stage (polymerization step (II)) in which ethylene and propylene are subsequently fed to the product of the first stage in such a proportion as to result in an ethylene content of from 20 to 80% by weight to produce a propylene-ethylene copolymer in an amount of from 5 to 40% by weight based on the total amount of the composition to be finally obtained.