Patent ID: 7776978

Claim:
A process for producing a 1-butene polymer comprising the step of polymerizing 1-butene and optionally ethylene, propylene or at least one alpha olefin of formula CH 2 ═CHZ, wherein Z is a C 3 -C 10 alkyl group, in the presence of a catalyst system obtained by contacting: a) at least a metallocene compound of formula (Ia) in the meso or meso-like form: wherein M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements; p is an integer from 0 to 3, being equal to the formal oxidation state of the metal M minus 2; X, same or different, is a hydrogen atom, a halogen atom, or a R, OR, OSO 2 CF 3 , OCOR, SR, NR 2 or PR 2 group, wherein R is a linear or branched, cyclic or acyclic, C 1 -C 40 -alkyl, C 2 -C 40 alkenyl, C 2 -C 40 alkynyl, C 6 -C 40 -aryl, C 7 -C 40 -alkylaryl or C 7 -C 40 -arylalkyl radicals; optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements; or two X can optionally form a substituted or unsubstituted butadienyl radical or a OR′O group wherein R′ is a divalent radical selected from C 1 -C 40 alkylidene, C 6 -C 40 arylidene, C 7 -C 40 alkylarylidene and C 7 -C 40 arylalkylidene radicals; L is a divalent C 1 -C 40 hydrocarbon radical optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements or a divalent silylene radical containing up to 5 silicon atom; R 1 and R 2 , equal to or different from each other, are C 1 -C 40 hydrocarbon radicals optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements; T, equal to or different from each other, is a moiety of formula (IIb): wherein the atom marked with the symbol * bonds the atom marked with the same symbol in the compound of formula (Ia); R 7 and R 8 , equal to or different from each other, are hydrogen atoms or C 1 -C 40 hydrocarbon radicals optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements; b) at least a metallocene compound of formula (Ib) in the racemic (rac) or racemic-like form: wherein the atoms marked with the symbol * bonds the atom marked with the same symbol in the moieties of formula (IIb); and c) an alumoxane or a compound that forms an alkyl metallocene cation, wherein 30 to 70 wt % of the 1-butene polymer is produced by the metallocene compound of formula (Ia) and 30 to 70 wt % of the 1-butene polymer is produced by the metallocene compound of formula (Ib).