Patent ID: 8278392
Filing Date: 2012-10-02
Classification: C08F,C08L

Abstract:
1. A process for producing a polypropylene resin composition comprising 5-50% by weight of a component (I) defined below and 50-95% by weight of a component (II) defined below, the amounts in % by weight being on the basis of a total of the weight of the component (I) expressed by W I and the weight of the component (II) expressed by W II , wherein the process comprises a 1st step and a 2nd step each defined below: component (I): a propylene-α-olefin block copolymer (I) which consists of 2-65% by weight of a polymer portion (I-A) obtained by polymerizing, in a first stage, monomers mainly including propylene and 35-98% by weight of a polymer portion (I-B) obtained by polymerizing, in a second stage, propylene and α-olefin other than propylene, the amounts in % by weight being on the basis of the whole weight of the copolymer (I), wherein the content of the α-olefin contained in the polymer portion (I-B) is 10-50% by weight on the basis of the whole weight of the monomers contained in the polymer portion (I-B), and the intrinsic viscosity [η] B of the polymer portion (I-B) is not less than 4 dl/g but not more than 10 dl/g; component (II): a propylene-ethylene block copolymer (II) which comprises 60-99% by weight of a polymer portion (II-A) obtained by polymerizing, in a first stage, monomers mainly including propylene and 1-40% by weight of a polymer portion (II-B) obtained by polymerizing, in a second stage, monomers including ethylene and propylene, the amounts in % by weight being on the basis of the whole weight of the copolymer (II), wherein the content of ethylene contained in the polymer portion (II-B) is 10-50% by weight on the basis of the whole weight of the monomers contained in the polymer portion (II-B), the intrinsic viscosity [η] B of the polymer portion (II-B) is not less than 1 dl/g but less than 3 dl/g, and the ratio of the intrinsic viscosity [η]B of the polymer portion (II-B) to the intrinsic viscosity [η]A of the polymer portion (II-A), [η]B/[η]A, is not less than 1 but not more than 4.5; 1st step: a step of melt-kneading the component (I) of an amount of W 2nd step: a step of melt-kneading the rest of the component (II) and the intermediate composition obtained in the 1st step together to produce a final composition.