Granted Patent B2

US 7,671,151 · App. 12/154,268 · Granted Mar 2, 2010

Abstract

Claims (11)

1. A process for making polyethylene having a broad molecular weight distribution and low level of long-chain branching, said process comprising polymerizing ethylene in a single reactor in the presence of hydrogen, a C 3 -C 10 α-olefin, and a catalyst comprising an activator and a supported, dialkylsilyl-bridged bis(indeno[1,2-b]indolyl)zirconium complex to produce polyethylene having an M w /M n greater than 10 and a viscosity enhancement factor of less than 2.5.

2. A continuous slurry or gas-phase process of claim 1 .

3. The process of claim 1 wherein the activator is selected from the group consisting of alumoxanes, alkylaluminum compounds, organoboranes, ionic borates, ionic aluminates, aluminoboronates, and combinations thereof.

4. The process of claim 1 wherein the complex has the structure:

wherein each R 1 is independently selected from the group consisting of C 1 -C 10 hydrocarbyl; each R 2 is independently selected from the group consisting of H, F, and C 1 -C 10 hydrocarbyl; and each L is independently selected from the group consisting of halide, alkoxy, aryloxy, siloxy, alkylamino, and C 1 -C 30 hydrocarbyl.

5. The process of claim 4 wherein R 1 and R 2 are methyl.

6. The process of claim 1 wherein the complex is a mixture of diastereomers.

7. The process of claim 6 wherein the diastereomers comprise racemic (rac) and meso stereoisomers, and the molar ratio of rac:meso stereoisomers is within the range of 0.1:1 to 1:0.1.

8. The process of claim 1 wherein the catalyst has an activity ratio as defined herein greater than 4.

9. The process of claim 8 wherein the introduction of 0.82 mmoles of hydrogen per mole of ethylene reduces the weight-average molecular weight by at least 60%.

10. The process of claim 1 wherein the polymerization is performed at a temperature within the range of about 40° C. to about 90° C.

Assignments (14)