| 摘要 |
A multistage process comprising the following steps: a) polymerizing propylene with optionally one or more monomers selected from ethylene and alpha olefins of formula CH2=CHT1, wherein T1 is a C2-C20 alkyl radical in the presence of a catalysts system, supported on an inert carrier comprising: i) a transition metal compound containing a ligand having a cyclopentadienyl skeleton; and ii) an alumoxane or a compound capable of forming an alkyl metallocene cation; b) contacting, under polymerization conditions, in a gas phase, ethylene with one or more alpha olefins of fonnula CH2 =CHT1, wherein T1 is a C2-C20 alkyl radical, and optionally a non-conjugated diene, in the presence of the polymer obtained in step a), in the presence of a weigh ratio hydrogen/hethylene higher than 1 ppm and optionally in the presence of an additional organo aluminum compound; wherein the amount of the polymer obtained in step a) ranges from 5% by weight and 90% by weight of the polymer obtained in the whole process and the amount of polymer obtained in step b) ranges from 10% by weight and 95% by weight of the polymer obtained in the whole process.
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