Claims
- 1. A process for preparing polyolefins, which comprises contacting a catalyst system comprising(a) a metallocene compound having the general formula: CpAXMQ1Q2Cp′A′X′M′Q1′Q2′wherein Cp and Cp′ we each independently a substituted or unsubstituted cyclopentadienyl moiety wherein each said cyclopentadienyl moiety is substituted or unsubstituted indenyl; M and M′ are each a metal chosen from Group IV B transition metals and vanadium, and coordinate to Cp and Cp′ respectively; X and X′ are each independently a substituted or unsubstituted Group VA or VIA heteroatom and coordinate to M and M′ respectively; A and A′ are bridging groups between Cp and X and between Cp′ and X′ respectively and are independently chosen from —SiR′2—O—SiR′2—SinR′m—, —CnR′m— and —CR′2′ SiR′2—CR′2—SiR′2—, in which each R′ is independently H or hydrocarbyl having 1 to 20 carbon atoms, n is an integer in the range 1 to 4 and m=2n; each Q1, Q2 and Q1′ and Q2′ is independently a coordinating group which is hydrogen, halogen, or hydrocarbyl having 1 to 20 carbon atoms and each of Q1 and Q1′ is coordinated to both M and M′; and (b) an aluminum- or boron-containing cocatalyst capable of activating the metallocene compound with at least one olefin in a reaction zone under polymerization conditions.
- 2. A process according to claim 1, wherein the olefin is propylene and the polyolefin is isotactic polypropylene.
- 3. A process according to claim 1, wherein the metallocene compound is (t-butylamido) (2-methyl-4,5-benzoinden-1-yl)-1,1-dimethyl silane zirconium chloride or (t-butylamido) (2-methyl-4,5-benzoinden-1-yl)-1,1-dimethyl silane titanium chloride.
- 4. A process according to claim 1 wherein said metallocene compound has an active site and wherein said active site has local C2 symmetry.
- 5. A process according to claim 1 wherein the indenyl moiety is benzoindenyl.
- 6. A process according to claim 1 wherein the cyclopentadienyl moiety is substituted at position 2 with a hydrocarbyl having 1 to 20 carbon atoms.
- 7. A process according to claim 1 wherein said metallocene compound has a dimeric structure.
- 8. A process according to claim 1, wherein the metal is Zr.
- 9. A process according to claim 1, wherein the heteroatom is nitrogen, phosphorus, oxygen or sulphur and is substituted with H, hydrocarbyl having 1 to 20 carbon atoms or silyl.
- 10. A process according to claim 9, wherein the heteroatom is nitrogen.
- 11. A process according to claim 1 wherein A is SiR′2.
- 12. A process according to claim 11, wherein each R′ is methyl.
- 13. A process according to claim 1, wherein the catalyst further comprises an aluminum- or boron-containing cocatalyst capable of activating the metallocene compound.
- 14. A process according to claim 1, wherein the catalyst system further comprises an inert support present application is a Divisional.
Priority Claims (1)
Number |
Date |
Country |
Kind |
98123747 |
Dec 1998 |
EP |
|
Parent Case Info
The present application is a Divisional Application of and claims benefit under 35 U.S.C. 120 U.S. patent application Ser. No. 09/459,836, filed Dec. 13, 1999, entitled “Polyolefin Production,” now U.S. Pat. No. 6,407,273.
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“Application of Amine Elimination for the Efficient Preparation of Electrophilic Ansa-Monocyclopentadienyl Group 4 Complexes Containing an Appended Amido Functionality. Structural Characterization of [(C5H4)SiMe2 (N-t-Bu)]Zrc12(NMe2H)”; Donald W. Carpenetti, et al., Organometallics, vol. 15 (II), p. 1573 (1996). |