A multistep process comprising the following steps:
- step a) polymerizing propylene and optionally at least one monomer selected from ethylene or alpha olefins of formula CH2═CHT1, wherein T1 is a C2-C10 alkyl radical, in the presence of a catalyst system comprising:
- i) at least one metallocene compound of formula (I):
- ii) an alumoxane or a compound that forms an alkyl metallocene cation;
- and optionally
- iii) a first organo aluminum compound, thereby forming a polymer in an amount;
- step b) contacting, under polymerization conditions, propylene or ethylene with at least one alpha olefin of formula CH2═CHT, wherein T is hydrogen or a C1-C10 alkyl radical, and optionally a non-conjugated diene, in the presence of the polymer obtained in step a) and optionally in the presence of a second organo aluminum compound, provided that a homopolymer is not produced, thereby forming a polymer in an amount;
- wherein the amount of the polymer obtained in step a) ranges from 5% by weight to 39% by weight of the polymer obtained in the whole process, and the amount of polymer obtained in step b) ranges from 61% by weight to 95% by weight of the polymer obtained in the whole process;
- wherein in the compound of formula (I),
- M is an atom of a transition metal selected from those belonging to group 4 of the Periodic Table of the Elements;
- X, equal to or different from each other, is a hydrogen atom, a halogen atom, an R, OR, OR′O, OSO2CF3, OCOR, SR, NR2 or PR2 group wherein R is a linear or branched, cyclic or acyclic, C1-C40-alkyl, C2-C40 alkenyl, C2-C40 alkynyl, C6-C40-aryl, C7-C40-alkylaryl or C7-C40-arylalkyl radical, optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements, and R′ is a C1-C20-alkylidene, C6-C20-arylidene, C7-C20-alkylarylidene, or C7-C20-arylalkylidene radical;
- L is a divalent bridging group selected from C1-C20 alkylidene, C3-C20 cycloalkylidene, C6-C20 arylidene, C7-C20 alkylarylidene, or a C7-C20 arylalkylidene radicals, optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements, or it is a silylidene radical containing up to 5 silicon atoms;
- R1 and R19 are different from each other and are a Z1′ or Z2′ group wherein Z1′ is an alpha branched C1-C20 hydrocarbon radical optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements, and Z2′ is a linear C1-C40 hydrocarbon radical optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements, with the proviso that if R1 or R19 are Z1′ then R19 or R1 are Z2′;
- R2 and R3, are part of 4-7 membered ring condensed to the benzene ring of the indenyl moiety, said ring optionally containing heteroatoms belonging to groups 13-16 of the Periodic Table of the Elements, the valence of each atom forming said ring is filled with R18 groups, wherein R18, equal to or different from each other, are hydrogen atoms or a C1-C40 hydrocarbon radical, said ring can be saturated or it can contain double bonds;
- R4 is a hydrogen atom or a C1-C40 hydrocarbon radical optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements;
- and
- W is an aromatic 5 or 6 membered ring that can contain heteroatoms belonging to groups 15-16 of the Periodic Table of the Elements, the valence of each atom of said ring is substituted with hydrogen atom or it can optionally be substituted with R5 groups, wherein R5, equal to or different from each other, are C1-C40 hydrocarbon radicals optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements;
- R20, R21 and R22, equal to or different from each other, are hydrogen atoms or C1-C40 hydrocarbon radicals optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements.