Patent ID: 7531605

Claim:
A process for producing a polyolefin-based resin composition which comprises: in a first polymerization stage, polymerizing or copolymerizing at least one monomer selected from the group consisting of ethylene, propylene, an α-olefin comprising 4 to 20 carbon atoms, a styrene and a cyclic olefin, in the presence of a catalyst comprising a combination of a catalyst component (A) comprising at least one compound selected from compounds of transition metals of Group 4 of the Periodic Table comprising a cyclopentadienyl skeleton structure and a promoter component (B), thereby obtaining a homopolymer or copolymer; and in a second polymerization stage, copolymerizing the homopolymer or the copolymer obtained in the first polymerization stage with at least one monomer selected from the group consisting of propylene, an α-olefin comprising 4 to 20 carbon atoms, a styrene and a cyclic olefin, in a presence of a polyene having at least two polymerizable double bonds in one molecule, wherein the polyene is at least one compound selected from the group consisting of a polyene of a styrene-compound, a styrene/α-olefin polyene which comprises a residue group of styrene and a residue group of an α-olefin in the same molecule, a compound of formula (VI) wherein n is 0, 1, or 2, a compound of formula (VII) wherein n is 0, 1, or 2, and m is an integer of from 1 to 11, and a compound of formula (VIII) wherein n is an integer of from 0 to 6; the polyene being used in an amount of 1.0×10 −7 to 1.0×10 −3 moles per 1 g of the homopolymer or the copolymer obtained in the first polymerization stage, with the proviso that, in the second polymerization stage, the homopolymer or the copolymer obtained in the first polymerization stage is not polymerized with ethylene, wherein the composition produced by the process satisfies the following requirements (a) to (c); (a) the intrinsic viscosity [η] 2 of a polyolefin obtained in the second polymerization stage is greater than the intrinsic viscosity [η] 1 of a polyolefin obtained in the first polymerization stage, (b) a ratio [η] 2 /[η] 1 =1.05 to 10, and (c) a content of the polyolefin obtained in the second polymerization stage in the polyolefin-based resin composition is 0.00 1 to 80% by weight.