A process for the preparation of a syndiotactic polyolefin

Claim 1

A process for the preparation of a syndiotactic polyolefin by polymerization or copolymerization of an olefin of the formula R"CH=CHRb, in which Ra and Rb are identical or different and denote a hydrogen atom or an alkyl radical having 1 to 28 carbon atoms, or Ra and Rb, with the atoms joining them, can form a ring, at a temperature of -60 to 200°C under n pressure of 0.5 to 100 bar in solution, suspension or the gas phase in the presence of a catalyst which consists of a metallocene as the transition metal component and an aluminoxane of the formula II (II) for the linear type and/or of the formula III (III) for the cyclic type, in which, in the formulae II and III, R9 denotes a C1-C6-alkyl group or phenyl or benzyl and n is an integer from 2 to 50, which comprises carrying out the polymerization in the presence of a catalyst, the transition metal component of which is a compound of the formula I (I) in which M1 is titanium, zirconium, vanadium, niobium or tantalum, R1 and R2 are identical or different and denote a hydrogen atom, a halogen atom, a C1-C10-alkyl group, a C1-C10-alkoxy group, a C6-C10-aryl group, a C6C10-aryloxy group, a C2-C10-alkenyl group, a C7-C40-arylalkyl group, a C7-C40-alkylaryl group or a C8-C40-arylalkenyl group, R3 and R4 are different and denote a mono- or polynuclear hydrocarbon radical which can form a sandwich structure with the central atom M1, R5 is = BR8, = AlR5, -Ge-, -Sn-, -O-, -S-, = SO, = SO2, = NR5, = CO, = PR6 or = P(O)R6, in which R5, R7 and R8 are identical or different and denote a hydrogen atom, a halogen atom, a C1-C10-alkyl group, a C1-C10-fluoroalkyl group, a C6-C10-fluoroaryl group, a C6-C10-aryl group, a C1-C10-alkoxy group, a C2-C10-alkenyl group, a C7-C40-arylalkyl group, a C8-C40-arylalkenyl group or a C7-C40 alkylaryl group, or R5 and R7 or R8 and R9, in each case with the atoms joining them, form a ring, and M2 is silicon, germanium or tin.