| 摘要 |
A polyolefin composition suitable for preparing films and sheets, comprising : (A) from 15 to 40 % by weight of a crystalline copolymer of propylene with a t least one alpha-olefin of formula H2C=CHR1, where R1 is H or a C2-8 linear o r branched alkyl, containing at least 90 % by weight of propylene, having solubility in xylene at room temperature lower than 15% by weight; (B) from 60 to 85 % by weight of an elastomeric fraction comprising: (1) a copolymer of propylene with ethylene, optionally containing 0.5 to 5 % by weight of a diene, containing from 20 to 35% by weight ethylene, and having solubility i n xylene at room temperature greater than 45% by weight, the intrinsic viscosi ty of the xylene soluble fraction ranging from 1.0 to 3.9 dl/g; and (2) a copolymer of ethylene with at least one alpha-olefin of formula H2C=CHR2, where R2 is a C2-8 linear or branched alkyl, optionally containing 0.5 to 5 % by weight of a diene, containing 15 % to 40 % by weight alpha-olefin, and having solubility in xylene at room temperature greater than 35% by weight, the intrinsic viscosity of the xylene soluble fraction ranging from 1.0 to 3 .0 dl/g; the (1)/(2) weight ratio ranging from 1:5 to 5:1. The polyolefin composition of the invention, preferably prepared by sequential polymerizati on in at least threestages, has a flexural modulus lower than 130 Mpa, shore D hardness lower than 40, and MFR >= 1.5 g/10min.
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