Use of a mixture of two metallocene regioisomers as catalyst component for preparing bimodal isotactic polyolefins

摘要

Use for preparing isotactic polyolefins of a metallocene catalyst component, which has the general formula: R" (CpR1R2) (Cp'Rn') MQ2 wherein Cp is a substituted cyclopentadienyl ring; Cp' is a substituted or unsubstituted fluorenyl ring; R" is a structural bridge imparting stereorigidity to the component; R1 is 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 different and chosen from hydrogen or hydrocarbyl of from 1 to 20 carbon atoms, R2 is a substituent on the cyclopentadienyl ring which is proximal to the 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, each R'n is the same or different and is hydrocarbyl having 1 to 20 carbon atoms in whrch o≤n≤8; M is a Group IVB transition metal or vanadium; and each Q is hydrocarbyl having 1 to 20 carbon atoms or is a halogen.