Patent ID: 6605676
Filing Date: 2003-08-12
Classification: C08F,Y10S

Abstract:
A process for obtaining homopolymers or copolymers of ethylene with wide bimodal or multimodal molecular weight distributions, wherein ethylene, alone or with an alpha olefin, is polymerized in the presence of a catalyst system which consists of:(a) a single supported or unsupported metallocene catalyst being a mono, or dicyclopentdienyl of transition metals in any of groups 4b, 5b, 6b of the Periodic Table of elements represented by the formulae: (C5Râ€²m)pRâ€³s(C5Râ€²m)MeQ3-p orRâ€³s(C5Râ€²m)2 MeQâ€²where (C5Râ€²m) is cyclopentadienyl or substituted cyclopentadienyl, each Râ€² may be the same or different and may be hydrogen, monohydrocarbon radicals selected from the group consisting alkyl, alkenyl, aryl, alkylaryl or arylalkyl containing from 1 to 20 carbon atoms, or two adjacent carbon atoms joined to form a C4-C6 ring, where Râ€³ is an alkylene radical containing from 1 to 4 carbon atoms, a dialkyl germanium, a dialkyl silicon radical or an alkylphosphine or amino radical joining two (C5Râ€²m) rings, Q is a hydrocarbon radical selected from the group consisting of aryl, alkyl, alkenyl, alkylaryl, and arylalkyl containing from 1 to 20 carbon atoms, optionally halogen, and each of said hydrocarbon radicals may be the same or different, Qâ€² is an alkylidine radical containing from 1 to 20 carbon atoms, Me is a transition metal in groups 4b, 5b or 6b of the Periodic Table of elements, s is 0 or 1, p is 0, 1 or 2; when p is 0, s is 0; m is 4 if s is 1 and m is 5 if s is 0;(b) a co-catalyst formed by a combination of an aluminum compound having Alâ€”O bonds corresponding to the formulae: (RAlO)n orR(Râ€”Alâ€”O)n AlR2 where R is an alkyl or aryl group containing from 1 to 20 carbon atoms, and n is a number from 1 to 20, and at least one Boron compound corresponding to the general formulae:BX1X2X3 or(Y) (BX1X2X3X4) where B is boron, and X1, X2, X3, X4 are the same or different and may be hydride, halide, alkyl containing from 1 to 20 carbon atoms, substituted alkyls containing from 1 to 20 carbon atoms in which one or more hydrogens are substituted by halogens, metal hydrocarbon radicals(organometalloids) in which each substitution contains from 1 to 20 carbon atoms, and the metal is selected from the group consisting of group 4a of the Periodic Table of elements, aryl, and substituted aryls containing from 6 to 20 carbon atoms and Y is a Bronsted acid, optionally in the presence of at least one alkyl aluminum of formulaAlRâ€³â€²3 where the Râ€³â€² groups, which may be the same or different, may be alkyls or aryls containing from 1 to 20 carbon atoms or halogens, and Al is aluminum.