Preparation of multimodal polyethylene

• US 7,473,745 B2
• Filed: 09/02/2005
• Issued: 01/06/2009
• Est. Priority Date: 09/02/2005
• Status: Expired due to Fees

• Current Assignee: Equistar Chemicals LP (Lyondellbasell Industries NV)
• Original Assignee: Equistar Chemicals LP (Lyondellbasell Industries NV)
• Inventors: Holland, Charles S., Vargas, Edward S., Mack, Mark P., Nagy, Sandor M., Gates, Charles H. Jr., Chandrashekar, Venki, Nagy, Natalia, Merrick-Mack, Jean A.
• Primary Examiner(s): Lipman; Bernard
• Application Number:
  US11/218,888
• Publication Number:
  US 20070055021A1
• Time in Patent Office: 1,222 Days
• Field of Search: 526/113, 526/118, 526/172, 526/161, 526/65, 526/73, 526/79, 526/905, 526/348.2, 526/348.3, 526/348.6, 526/352
• US Class Current: 526/65
• CPC Class Codes: C08F 10/02 Ethene
• CPC Class Codes: C08F 110/02 Ethene
• CPC Class Codes: C08F 2/001 Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer C08F295/00, C08F297/00 take precedence
• CPC Class Codes: C08F 210/08 Butenes
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 2500/05 Bimodal or multimodal molecular weight distribution
• CPC Class Codes: C08F 2500/09 Long chain branches
• 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
• CPC Class Codes: C08F 4/65927 two cyclopentadienyl rings being mutually bridged
• CPC Class Codes: C08L 23/00 Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 23/04 Homopolymers or copolymers of ethene
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 23/0807 Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
• CPC Class Codes: C08L 2666/06 Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof

Abstract

Disclosed is a polyethylene composition. The composition comprises single-site multimodal resin A and single-site multimodal resin B, wherein resin A differs from resin B in molecular weight, in monomeric composition, in density, in long chain branch concentration or distribution, or in combinations thereof. Disclosed is also a method for making the polyethylene composition. The method comprises polymerizing, in the presence of two or more single-site catalysts, ethylene or its mixture with a C₃-C₁₀ α-olefin to form a first multimodal resin and continuing the polymerization in the presence of the same catalysts but in a different hydrogen concentration, in a different monomer composition, or at a different temperature to form a second multimodal resin.

Claims

1. A multi-stage process comprising:

(a) polymerizing, in the presence of two or more single-site catalysts, ethylene or a mixture of ethylene and a C₃ to C₁₀ α

-olefin at a hydrogen/monomer molar ratio within the range of about 0.0001/1 to about 10/1 to produce a first multimodal resin; and

(b) continuing the polymerization in the presence of the same catalysts as in stage (a) at a reduced hydrogen/monomer ratio to produce a second multimodal resin;

wherein the single-site catalysts comprise an indenoindolyl catalyst.

2. The process of claim 1, wherein stage (b) is performed at an increased α

-olefin/ethylene ratio.

3. The process of claim 1, wherein the single-site catalysts comprise a non-bridged indenoindolyl catalyst and a bridged indenoindolyl catalyst.

4. The process of claim 3, wherein the non-bridged and bridged catalysts are mixed and supported together.

5. A multi-stage process comprising:

(a) polymerizing, in the presence of two single-site catalysts, ethylene or a mixture of ethylene and a C₃ to C₁₀ α

-olefin at a hydrogen/monomer molar ratio less than 1/1 to produce a first multimodal resin; and

(b) continuing the polymerization in the presence of the same catalysts as in stage (a) at an increased hydrogen/monomer molar ratio to produce a second multimodal resin;

wherein the single-site catalysts comprise an indenoindolyl catalyst.

6. The process of claim 5, wherein the single-site catalysts comprise a non-bridged indenoindolyl catalyst and a bridged indenoindolyl catalyst.

7. The process of claim 6, wherein the non-bridged and the bridged catalysts are mixed and supported together.