| abstract |
One or more metallocene compounds of formula (I) wherein M is a transition metal atom; p is an integer from 0 to 3; X is the same or different and is a hydrogen atom, a halogen atom or a hydrocarbon group; L is a divalent bridging R 1 and R 2 which are C 1 to C 20 alkyl groups; T is equal to or different from each other and is a moiety of formula (IIb) or (IIa) (where R 3 , R 4 , R 5 , R 6 , R 7 , R 3 ′ , R 4 ′ , R 5 ′ , R 6 ′ and R 7 ′ are a hydrogen atom or a hydrocarbon group, provided that R 3 , R 4 , R 5 , R 6 , R 7 are not hydrogen; R 11 is a hydrogen atom or a hydrocarbon group; R 8 , R 9 and R 10 are a hydrogen atom or a hydrocarbon group) A step of polymerizing propylene in the presence of a catalyst system comprising, and further comprising contacting ethylene and one or more comonomers in the gas phase under polymerization conditions. Here, the amount of polymer obtained in the first step ranges from 5% to 90% by weight of the polymer obtained in the overall process. [Selection figure] None |