| 摘要 |
Use of a metallocene catalyst component for the preparation of a polyolefin which comprises an isotactic or polyolefin syndiotactic/isotactic block polyolefin having a monomer length of up to C10, which component has the general formula: R"(CpR1R2R3)(Cp'R1'R2')MQ2 wherein Cp is a cyclopentadienyl ring substituted with at least one substituent; Cp' is a substituted fluoren yl ring; R" is a structural bridge imparting stereorigidity to the component; R 1 is optionally a substituent on the cyclopentadienyl ring which is distal to the bridge, which distal substituent comprises a bulky group of the formula XR*3 in which X is chosen from Group IVA, and each R* is the same or differe nt and chosen from hydrogen or hydrocarbyl of from 1 to 20 carbon atoms, R2 is optionally a substituent on the cyclopentadienyl ring which is proximal to t he bridge and positioned non-vicinal to the distal substituent and is of the formula YR#3 in which Y is chosen from group IVA, and each R# is the same or different and chosen from hydrogen or hydrocarbyl of 1 to 7 carbon atoms, R3 is optionally a substituent on the cyclopentadienyl ring which is proximal t o the bridge and is a hydrogen atom or is of the formula ZR$3, in w hich Z is chosen from group IVA, and each R$is the same of different an d chosen from hydrogen or hydrocarbyl of 1 to 7 carbon atoms, R1' and R2' are each independently substituent groups on the fluorenyl ring, one of which is a group of the formula AR'''3, in which A is chosen from Group IVA, and each R''' is independently hydrogen or a hydrocarbyl having 1 to 20 carbon atoms and the other is hydrogen or a second group of the formula AR'''3; M is a Group IVB transition metal or vanadium; and each Q is hydrocarbyl having 1 t o 20 carbon atoms or is a halogen.
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