Olefin polymerization process
View Patent ↗A process for polymerizing ethylene is disclosed. The process comprises polymerizing ethylene in the presence of a catalyst system which comprises a bridged indenoindolyl transition metal complex on a support material, an alkylalumoxane, a titanium tetralkoxide, and a branched alkyl aluminum compound. The process provides polyethylenes with low density from ethylene alone.
1. A process which comprises polymerizing ethylene in the presence of a catalyst system which comprises a bridged indenoindolyl transition metal complex on a support material, an alkylalumoxane, a titanium tetralkoxide, and a branched alkyl aluminum compound.
2. The process of claim 1 wherein the support material is silica.
3. The process of claim 2 wherein the alkylalumoxane is combined with the silica prior to addition of the bridged indenoindolyl transition metal complex to the silica.
4. The process of claim 1 wherein the titanium tetraalkoxide derives from one or more C 1 to C 8 alcohols.
5. The process of claim 4 wherein the titanium tetralkoxide is selected from the group consisting of titanium(IV) methoxide, titanium(IV) ethoxide, titanium(IV) propoxide, titanium(IV) isopropoxide, titanium(IV) butoxide, and titanium(IV) 2-ethylhexoxide.
6. The process of claim 1 wherein the branched alkyl aluminum compound has the formula RAIX 2 in which R is a branched C 3 to C 8 alkyl group and each X is independently selected from the group consisting of halide and linear or branched alkyl.
7. The process of claim 6 wherein R is isobutyl.
8. The process of claim 7 wherein the branched alkyl aluminum compound is triisobutylaluminum.
9. The process of claim 1 wherein the bridged indenoindolyl complex has a structure selected from the group consisting of:
wherein M is a Group 3 to 10 transition metal; each L is independently selected from the group consisting of halide, alkoxy, aryloxy, siloxy, alkylamino, and C 1 -C 30 hydrocarbyl; L′ is selected from the group consisting of alkylamido, substituted or unsubstituted cyclopentadienyl, fluorenyl, indenyl, boraaryl, pyrrolyl, azaborolinyl and indenoindolyl; x satisfies the valence of M; R 1 is selected from the group consisting of C 1 -C 30 hydrocarbyl, dialkylboryl and trialkylsilyl; each R 2 is independently selected from the group consisting of C 1 -C 30 hydrocarbyl, H, F, Cl and Br; G is a divalent radical selected from the group consisting of hydrocarbyl and heteroatom-containing alkylene radicals, diorganosilyl radicals, diorganogermanium radicals, organoboranyl radicals, organophosphinyl radicals, and diorganotin radicals.
10. The process of claim 9 wherein L′ is selected from the group consisting of substituted or unsubstituted cyclopentadienyl, fluorenyl, indenyl, and indenoindolyl.
11. The process of claim 1 wherein the alkylalumoxane is methylalumoxane.
12. The process of claim 1 comprising polymerizing ethylene in the presence of a second olefin.
13. The process of claim 1 performed at a temperature within the range of about 30° C. to about 100° C.
14. A slurry polymerization process of claim 1 .
15. A gas-phase polymerization process of claim 1 .
16. The process of claim 1 wherein the bridged indenoindolyl transition metal complex is supported on methylalumoxane-treated silica and the supported complex, the titanium tetraalkoxide, and the branched alkyl aluminum compound are each independently added to a polymerization reactor.
17. The process of claim 1 wherein the resulting polyethylene has a density less than 0.94 g/cm 3 .
18. The process of claim 1 wherein the resulting polyethylene has a density less than 0.91 g/cm 3 .
19. The process of claim 1 wherein the resulting polyethylene has, by 13 C NMR spectroscopy, more than 10 ethyl branches per 1000 carbons.
20. The process of claim 1 wherein the resulting polyethylene has, by 13 C NMR spectroscopy, more than 30 ethyl branches per 1000 carbons.