Method for making polyolefins

• US 20030195306A1
• Filed: 04/16/2002
• Published: 10/16/2003
• Est. Priority Date: 04/16/2002
• Status: Active Grant

• Current Assignee: Equistar Chemicals LP (Lyondellbasell Industries NV)
• Original Assignee: Equistar Chemicals LP (Lyondellbasell Industries NV)
• Inventors: Neal-Hawkins, Karen L., Nagy, Sandor, Wang, Shaotian, Mutchler, Joel A., Mack, Mark P., Tsuie, Barbara M., Johnson, Kenneth W., Lynch, Michael W., Merrick-Mack, Jean A., Lee, Clifford C.
• Granted Patent: US 6,908,972 B2
• Time in Patent Office: Days
• US Class Current: 526/127
• CPC Class Codes: C08F 110/02 Ethene
• CPC Class Codes: C08F 210/02 Ethene
• CPC Class Codes: C08F 210/08 Butenes
• CPC Class Codes: C08F 210/14 Monomers containing five or more carbon atoms
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 2500/07 High density, i.e. > 0.95 g/cm3
• CPC Class Codes: C08F 2500/08 Low density, i.e. < 0.91 g/cm3
• CPC Class Codes: C08F 2500/09 Long chain branches
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 4/65908 in combination with an ionising compound other than alumoxane, e.g. (C6F5)4B-X+
• CPC Class Codes: C08F 4/65912 in combination with an organoaluminium compound
• CPC Class Codes: C08F 4/65916 supported on a carrier, e.g. silica, MgCl2, polymer
• CPC Class Codes: C08F 4/65927 two cyclopentadienyl rings being mutually bridged

Abstract

A method for making ethylene polymers and copolymers is disclosed. The method uses a catalyst system comprising a low level of an aluminum-containing activator, a bridged indenoindolyl transition metal complex, and a treated silica support. The method enables economical preparation of ethylene copolymers having very low density. The silica-supported, bridged complexes incorporate comonomers efficiently and are valuable for a commercial slurry loop process. Use of a bridged indeno[2,1-b]indolyl complex provides exceptionally efficient comonomer incorporation, and gives polymers with a substantial and controlled level of long-chain branching. The method facilitates the production of a wide variety of polyolefins, from HDPE to plastomers.

Claims

1. A method which comprises copolymerizing ethylene and a 1-olefin in the presence of a catalyst system comprising (a) an aluminum-containing activator;

(b) a bridged, indenoindolyl Group 3-10 transition metal complex; and

(c) a treated silica support, to produce a linear low density or plastomeric ethylene copolymer having a density less than 0.930 g/cm³, wherein the catalyst system has an aluminum;

transition metal [Al;

M] mole ratio less than 500.

2. The method of claim 1 wherein the complex includes a Group 4-6 transition metal.

3. The method of claim 1 wherein the complex includes an indeno[2,1-b]indolyl ligand.

4. The method of claim 1 wherein the complex includes an indeno[1,2-b]indolyl ligand.

5. The method of claim 1 wherein the complex incorporates a bridging group selected from the group consisting of methylene, dimethylene, isopropylidene, and dimethylsilyl.

6. The method of claim 1 wherein an indenoindolyl ligand of the complex is covalently bridged to a polymerization-stable ligand selected from the group consisting of cyclopentadienyl, indenyl, and fluorenyl.

7. The method of claim 1 wherein the activator is methyl-alumoxane or a mixture of methylalumoxane and an organoborane.

8. The method of claim 7 wherein the organoborane is tris-(pentafluorophenyl)borane.

9. The method of claim 1 wherein the silica support is treated with an alumoxane.

10. The method of claim 1 wherein the [Al:

M] mole ratio is less than about 250.

11. The method of claim 1 wherein the 1-olefin is selected from the group consisting of propylene, 1-butene, 1-hexene, 1-octene, and mixtures thereof.

12. The method of claim 1 wherein the ethylene copolymer has a density less than 0.920 g/cm³.

13. The method of claim 1 wherein the ethylene copolymer has a density less than 0.910 g/cm³.

14. The method of claim 1 wherein the ethylene copolymer has a density less than 0.900 g/cm³.

15. The method of claim 1 wherein the ethylene copolymer has a Mw/Mn<

4.0.

16. The method of claim 1 performed in the presence of a chain-transfer agent selected from the group consisting of hydrogen, organozinc compounds, and organoaluminum compounds, to produce a copolymer having Mw<

150,000.

17. The method of claim 16 wherein the chain-transfer agent is triethylaluminum in combination with hydrogen, and the copolymer has a Mw/Mn<

3.5.

18. The method of claim 1 performed in the absence of a chain-transfer agent to produce a copolymer having Mw>

400,000.

19. The method of claim 1 wherein the complex incorporates a fluorenyl ligand, and the resulting copolymer has a Mw>

200,000.

20. A method which comprises polymerizing ethylene and optionally a 1-olefin in the presence of a catalyst system comprising (a) an aluminum-containing activator;

(b) a bridged, indeno[2,1-b]indolyl Group 3-10 transition metal complex; and

(c) a treated silica support, to produce an ethylene polymer or copolymer having a long-chain-branching index>

0.2, wherein the catalyst system has an aluminum;

transition metal [Al;

M] mole ratio less than 500.

21. The method of claim 20 wherein the complex incorporates a bridging group selected from the group consisting of methylene, dimethylene, isopropylidene, and dimethylsilyl.

22. The method of claim 20 wherein an indeno[2,1-b]indolyl ligand of the complex is covalently bridged to a polymerization-stable ligand selected from the group consisting of cyclopentadienyl, indenyl, and fluorenyl.

23. The method of claim 20 wherein the [Al:

M] mole ratio is less than about 250.

24. The method of claim 20 wherein the polymer or copolymer has a long-chain-branching index>

0.5.

25. The method of claim 20 wherein the polymer or copolymer has a long-chain-branching index>

1.0.

26. The method of claim 20 wherein the polymer or copolymer has a Mw/Mn<

4.0.

27. The method of claim 20 wherein the 1-olefin is selected from the group consisting of propylene, 1-butene, 1-hexene, 1-octene, and mixtures thereof.

28. The method of claim 27 wherein the copolymer is plastomeric and has a density less than 0.915 g/cm³.

29. The method of claim 28 wherein the copolymer has a density less than 0.900 g/cm³.

30. The method of claim 20 wherein the transition metal complex incorporates a dimethylsilyl bridging group, the 1-olefin is 1-hexene, the mole ratio of 1-hexene to ethylene is at least about 0.3, and the resulting copolymer has a long-chain-branching index>

1.0.