High density polyethylene

• US 7,595,364 B2
• Filed: 12/07/2005
• Issued: 09/29/2009
• Est. Priority Date: 12/07/2005
• Status: Active Grant

• Current Assignee: Univation Technologies LLC (Dow, Inc.)
• Original Assignee: Univation Technologies LLC (Dow, Inc.)
• Inventors: Shannon, Porter Clarke, Ehrman, Fred D.
• Primary Examiner(s): Nutter; Nathan M
• Application Number:
  US11/296,104
• Publication Number:
  US 20070129496A1
• Time in Patent Office: 1,392 Days
• Field of Search: 525/191, 525/240
• US Class Current: 525/191
• 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 2500/04 Broad molecular weight distribution, i.e. Mw/Mn > 6
• CPC Class Codes: C08F 2500/05 Bimodal or multimodal molecular weight distribution
• CPC Class Codes: C08F 2500/07 High density, i.e. > 0.95 g/cm3
• CPC Class Codes: C08F 2500/10 Short chain branches
• CPC Class Codes: C08F 2500/11 Melt tension or melt strength
• 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 4/65925 two cyclopentadienyl rings being mutually non-bridged

Abstract

Multimodal polyethylenes possessing a density from 0.940 to 0.965 g/cm³, and an I₂₁ from 4 to 20 dg/min, and comprising a low molecular weight ethylene copolymer having a weight average molecular weight from 5,000 amu to 50,000 amu; and a high molecular weight ethylene copolymer having a weight average molecular weight from 60,000 amu to 800,000 amu, both components having a desirable balance of short chain branching making the multimodal polyethylene suitable for films, pipes, rotomolding applications and blow molding applications.

Claims

1. A multimodal polyethylene possessing a density from 0.940 to 0.965 g/cm³, and an I₂₁ from 4 to 20 dg/min, and comprising the following ethylene copolymers:

(a) a low molecular weight ethylene copolymer having a weight average molecular weight from 5,000 amu to 50,000 amu and having a short chain branching index from 2.5 to 4.5; and

(b) a high molecular weight ethylene copolymer having a weight average molecular weight from 60,000 amu to 800,000 amu and having a short chain branching index from 1 to 2.5.

2. The multimodal polyethylene of claim 1, wherein the ratio of the branching index of the low and high molecular weight fraction is in the range of 1.5 to 4.5.

3. The multimodal polyethylene of claim 1, wherein the low molecular weight ethylene copolymer has a short chain branching index from 3 to 4.

4. The multimodal polyethylene of claim 1, wherein the molecular weight distribution of the polyethylene ranges from 30 to 100.

5. The multimodal polyethylene of claim 1, wherein the weight fraction of the high molecular weight ethylene copolymer ranges from 0.3 to 0.7.

6. The multimodal polyethylene of claim 1, wherein the polyethylene is produced in a single continuous fluidized bed gas phase reactor.

7. The multimodal polyethylene of claim 4, wherein the polyethylene is produced by contacting ethylene and a C₃-C₈ α

-olefin with a bimetallic catalyst composition comprising a metallocene and a non-metallocene catalyst.

8. The multimodal polyethylene of claim 7, wherein the metallocene is a bis-cyclopentadienyl complex of a Group 4 metal;

wherein the cyclopentadienyl is selected from the group consisting of cyclopentadienyl, indenyl, tetrahydroindenyl, and substituted versions thereof.

9. The multimodal polyethylene of claim 8, wherein the metallocene is unsymmetrically substituted.

10. The multimodal polyethylene of claim 1, wherein a film made from the multimodal polyethylene of at least 12 μ

m in thickness possesses a dart drop of at least 200 grams;

the film having been made at a 4;

1 BUR on a 50 mm (L/D=18) grooved feed grooved feed extruder with 100 mm die and 1.0 mm die gap.

11. The multimodal polyethylene of claim 1, wherein a pipe made from the multimodal polyethylene has a PENT (ASTM D F1473-01, 3.0 MPa and 80°

C.) value of at least 150.

12. The multimodal polyethylene of claim 1 consisting essentially of one high molecular weight fraction and one low molecular weight fraction.

13. A rotomolded product made from the multimodal polyethylene of claim 1.

14. A blow molded product made from the multimodal polyethylene of claim 1.

15. A multimodal polyethylene possessing a density from 0.940 to 0.965 g/cm³, and an I21 from 4 to 20 dg/min, and comprising the following ethylene copolymers:

(a) a low molecular weight ethylene copolymer having a weight average molecular weight from 5,000 amu to 50,000 amu; and

(b) a high molecular weight ethylene copolymer having a weight average molecular weight from 60,000 amu to 800,000 amu;

wherein the weight fraction of the high molecular weight ethylene copolymer relative to the entire multimodal composition ranges from 0.3 to 0.7; and

wherein the ratio of the branching index of the low and high molecular weight ethylene copolymers ranges from 1.2 to 6.0.

16. The multimodal polyethylene of claim 15, wherein the ratio of the branching index of the low and high molecular weight ethylene copolymers ranges from 1.5 to 5.0.

17. The multimodal polyethylene of claim 15, wherein the ratio of the branching index of the low and high molecular weight ethylene copolymers ranges from 1.8 to 4.5.

18. The multimodal polyethylene of claim 15, wherein the polyethylene is produced in a single continuous fluidized bed gas phase reactor.

19. The multimodal polyethylene of claim 18, wherein the polyethylene is produced by contacting ethylene and a C₃-C₈ α

-olefin with a bimetallic catalyst composition comprising a metallocene and a non-metallocene catalyst.

20. The multimodal polyethylene of claim 19, wherein the metallocene is a bis-cyclopentadienyl complex of a Group 4 metal;

wherein the cyclopentadienyl is selected from the group consisting of cyclopentadienyl, indenyl, tetrahydroindenyl, and substituted versions thereof.

21. The multimodal polyethylene of claim 19, wherein the metallocene is unsymmetrically substituted.