Patent ID: 7649052

Claim:
A heterophasic polyolefin composition comprising (percent by weight): (A) from 50 to 80% by weight of a crystalline propylene polymer having a polydispersity index value from 5.2 to 10, and a content of isotactic pentads (mmmm), measured by 13 C-NMR on a fraction insoluble in xylene at 25° C., higher than 97.5 molar %; said polymer being selected from a propylene homopolymer, and a copolymer of propylene and at least one comonomer selected from ethylene and an α-olefin of formula H 2 C═CHR, where R is a C 2-6 linear or branched alkyl radical, comprising at least 95% of recurring units deriving from propylene; (B) from 5 to 20% by weight of a first elastomeric ethylene/propylene copolymer; said first elastomeric ethylene/propylene copolymer comprising from 25% to less than 40% by weight of ethylene, and is soluble in xylene at room temperature in an amount from higher than 85% to 95% by weight, wherein the xylene soluble fraction has an intrinsic viscosity [η] ranging from 2.5 to 4.5 dL/g; and (C) from 10 to 40% by weight of a second elastomeric ethylene/propylene copolymer; said second elastomeric ethylene/propylene copolymer comprising from 50% up to 75% by weight of ethylene, and is soluble in xylene at room temperature in an amount from 50% to 85% by weight, wherein the xylene soluble fraction has an intrinsic viscosity [η] ranging from 1.8 to 4.0 dL/g; wherein the sum of amounts of copolymer (B) and copolymer (C) ranges from 20 to 45% by weight based on the total amount of components (A) to (C), the total amount of ethylene based on the total amount of components (A) to (C) is up to 23% by weight, and the ratio between the ethylene content of the fraction insoluble in xylene at room temperature (C 2 xif) multiplied by the weight percentage of the fraction insoluble in xylene at room temperature (% XIF) and the ethylene content of the fraction soluble in xylene at room temperature (C 2 xsf) multiplied by the weight percentage of fraction soluble in xylene at room temperature (% SXF), demonstrated by the following formula, (C 2 xif×% XIF)/(C 2 xsf×% SXF), satisfies relation (I): C 2 ⁢ xif × % ⁢ ⁢ XIF C 2 ⁢ xsf × % ⁢ ⁢ SXF > 0.01 ⁢ ⁢ x + 0.261 , and wherein x is a total amount of ethylene.