Mixed metallocene catalyst systems containing a poor comonomer incorporator and a good comonomer incorporator

• US 20030088038A1
• Filed: 07/19/2002
• Published: 05/08/2003
• Est. Priority Date: 07/19/2001
• Status: Active Grant

• Current Assignee: Univation Technologies LLC (Dow, Inc.)
• Original Assignee: Univation Technologies LLC (Dow, Inc.)
• Inventors: Kao, Sun-Chueh, Lue, Ching-Tai, Szul, John F., Vaughan, George Alan, Farley, James McLeod, McKee, Matthew Gary
• Granted Patent: US 6,828,394 B2
• Time in Patent Office: Days
• US Class Current: 526/114
• CPC Class Codes: C08F 10/00 Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
• 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 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 2500/26 Use as polymer for film forming
• CPC Class Codes: C08F 4/65904 in combination with another component of C08F4/64
• 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 4/65922 containing at least two cyclopentadienyl rings, fused or not
• CPC Class Codes: Y02P 20/52 using catalysts, e.g. selective catalysts
• CPC Class Codes: Y10S 526/943 Polymerization with metallocene catalysts

Abstract

The present invention provides polymerization catalyst compounds, catalyst systems including these catalyst compounds, and to their use in the polymerization of ethylene and at least one comonomer. In particular, the invention provides a catalyst system comprising a poor comonomer incorporating catalyst compound and a good comonomer incorporating catalyst compound. Preferably, the low comonomer incorporating catalyst compound is a metallocene containing at least one substituted or unsubstituted fused ring cyclopentadienyl based ligand which is substantially directed to the front of the molecule, contains a long bridging group, or which contains a methyl substitution pattern which correlates to poor comonomer incorporation. The invention also provides methods of selecting the poor comonomer incorporating metallocene to pair with the good comonomer incorporating metallocene to produce polymers that are easy to process into a variety of articles, especially polyethylene based film, having enhanced properties.

Claims

1. A process for polymerizing olefin(s) to produce a polymer product, the process comprising a contacting ethylene and at least one comonomer with a catalyst system, wherein the catalyst system comprises a poor comonomer incorporating catalyst compound having at least one fused ring cyclopentadienyl based ligand and a good comonomer incorporating catalyst compound, and wherein the polymer product has a bimodal composition distribution.

2. The process of claim 1 wherein the poor comonomer incorporating catalyst compound comprises at least one fused ring cyclopentadienyl based ligand directed to the front of the molecule by an angle α

which is greater than 30 degrees.

3. The process of claim 2 wherein α

is greater than 60°

.

4. The process of claim 2 wherein α

is greater than 80°

.

5. The process of claim 1 wherein the poor comonomer incorporating metallocene catalyst compound contains a bridging group having greater than 2 atoms.

6. The process of claim 5 wherein the bridging group is represented by a formula selected from the group consisting of R′

₂Si—

NR′

—

R′

₂Si, and R′

₂Si—

O—

R′

₂Si, wherein each R′

is independently a hydride radical or a hydrocarbyl radical.

7. The process of claim 2 wherein the poor comonomer incorporating catalyst compound comprises two fused ring cyclopentadienyl based ligands, wherein the angle α

of one of the two ligands is about 70°

to about 90° and

wherein angle α

of the second of the two ligands is greater than 15°

.

8. The process of claim 7 wherein the angle α

of one of the two ligands is about 70°

to about 90° and

wherein angle α

of the second of the two ligands is greater than 45°

.

9. The process of claim 1 wherein the poor comonomer incorporating catalyst compound is selected from the group consisting of O(Me₂SiInd)₂ZrCl₂, O(Me₂SiFluorenyl)₂ZrCl₂ O(Me₂SiInd)₂HfCl₂ O(Me₂Si[Me₃Cp])₂ZrCl₂, O(Ph₂SiInd)₂ZrCl₂, RN(Me₂SiInd)₂ZrCl₂, and O(Me₂Si[Me₃Cp])(Me₂SiInd)ZrCl₂, wherein Ind represents an Indenyl group.

10. The process of claim 1 wherein the poor comonomer incorporating metallocene catalyst compound is a 1-substituted bisindenylzirconium dichloride.

11. The process of claim 10 wherein the 1-substituted bisindenylzirconium dichloride is substituted with an alkyl group selected from the group consisting of a methyl group, an ethyl group and a propyl group.

12. The process of claim 1 wherein the polymer product is film.

13. The process of claim 1 wherein the process is a gas phase process.

14. The process of claim 1 wherein the poor comonomer incorporating metallocene catalyst compound is present in a form selected from the group consisting of racemic, meso, and racemic and meso.

15. The process of claim 1 wherein the poor comonomer incorporating catalyst compound requires a comonomer to monomer mole ratio at least two times that of the good comonomer incorporating catalyst compound to prepare the same density polymer.

16. The process of claim 1 wherein the poor comonomer incorporating catalyst compound requires a comonomer to monomer mole ratio of at least three times that of the good comonomer incorporating catalyst compound.

17. The process of claim 1 wherein the poor comonomer incorporating catalyst compound requires a comonomer to monomer mole ratio of at least four times that of the good comonomer incorporating catalyst compound.

18. The process of claim 1 wherein the poor comonomer incorporating catalyst compound requires a comonomer to monomer mole ratio of at least five times that of the good comonomer incorporating catalyst compound.

19. The process of claim 1 wherein the catalyst system is prepared by mixing a pre-supported activator in a medium of a solvent or a non-solvent to form a slurry, then contacting the poor comonomer incorporating catalyst compound and the good comonomer incorporating catalyst compound with the slurry.

20. The process of claim 19 wherein the medium is oil or hydrocarbon.

21. The process of claim 1 wherein the catalyst system comprises an aluminum-containing activator and the aluminum to transition metal mole ratio is greater than 115:

1.

22. The process of claim 1 wherein the catalyst system comprises an aluminum-containing activator and the aluminum to transition metal mole ratio is greater than 200:

1.

23. The process of claim 1 wherein the mole ratio of good comonomer incorporating catalyst compound to poor comonomer incorporating catalyst compound is greater than 1:

1.

24. The process of claim 1 wherein the mole ratio of good comonomer incorporating catalyst compound to poor comonomer incorporating catalyst compound is greater than 3:

1.

25. The process of claim 1 wherein the mole ratio of good comonomer incorporating catalyst compound to poor comonomer incorporating catalyst compound is greater than 5:

1.

26. The process of claim 1 wherein good comonomer incorporating catalyst compound and the poor comonomer incorporating catalyst compound are supported separately and fed into the polymerization reactor separately or are fed as a mixture of separately supported catalyst systems.