Equistar Chemicals, LP

Jean A Merrick-Mack

Sandor M Nagy

Shaotian Wang

Mark P Mack

Natalia Nagy

Barbara M Tsuie

Charles S Holland

Leonard V Cribbs

Philip J Garrison

Edward S Vargas

Paula L Nygard

Bradley P Etherton

Wallace W Yau

Venki Chandrashekar

James H Meas

Lawrence R Wallace

Charles H Gates, Jr

Everett O Lewis

Danny L Wise

Joel A Mutchler

Michael W Lynch

Gregory G Hlatky

Linda N Winslow

Clifford C Lee

Sebastian Joseph

Kenneth W Johnson

Karen L Neal-Hawkins

Thomas J Schwab

James Ronald Clark

Kelly L Williams

Kenneth J Klug

Resin blends useful for pipe and blow-molded articles are disclosed. The blends comprise a low-molecular-weight, high-density polyethylene and a high-molecular-weight, low-density ethylene copolymer. The high-molecular-weight component is made with a bridged indenoindolyl Group 4 metal complex having open architecture. Blends of the invention uniquely have high molecular weight (M&#x3e;200,000) and low levels of long-chain branching. A quick, convenient approach for estimating levels of long-chain branching in polyethylenes from gel permeation chromatography and dynamic oscillatory rheometry ('viscosity enhancement factor') is disclosed.

Polyolefin resin blends for crack-resistant pipe

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 C-C&#x3b1;-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.

Preparation of multimodal polyethylene

A slurry process for polymerizing ethylene is disclosed. The process comprises polymerizing ethylene in the presence of an &#x3b1;-olefin, hydrogen, and a catalyst comprising an activator and a supported, dimethylsilyl-bridged bis(indenoindolyl)zirconium complex. The process has high catalyst activity and produces polyethylene having a broad molecular weight distribution.

Olefin polymerization process

A slurry process for polymerizing ethylene is disclosed. The process comprises polymerizing ethylene in the presence of an &#x3b1;-olefin and a catalyst comprising an activator and a supported bridged bis-indeno[2,1-b]indolyl zirconium complex. The process uses a highly active catalyst and provides polyethylene characterized by a high level of long-chain branching.

A slurry process for polymerizing ethylene is disclosed. The process comprises polymerizing ethylene in the presence of an &#x3b1;-olefin and a catalyst comprising an activator and a supported bridged indeno[1,2-b]indolyl zirconium complex. The process produces polyethylene characterized by good incorporation of the &#x3b1;-olefin and moderate long-chain branching. The process is capable of forming high molecular weight polyethylene and has good catalyst activity.

Ethylene copolymers valuable for films, coatings, sheets, and molded articles are disclosed. Some of the copolymers have a long-chain-branching index from 0.25 to 0.60 and a gpcBR index from 0.1 to 0.7. Others have a primary DSC melting point that is less than its secondary DSC melting point. Also disclosed is LLDPE in which the weight percentage of the low-temperature elution fraction exceeds that of the high-temperature fraction, and wherein the Mof the low-temperature fraction exceeds that of the high-temperature fraction. The ethylene copolymers process easily, even at low melt indices, and films from the copolymers have high stiffness, good impact resistance, and high heat-seal strength over a wide temperature range.

Polyolefin compositions

An ethylene polymerization process is disclosed. Ethylene is polymerized in two slurry reaction zones with a C-Calpha-olefin in the presence of a single-site catalyst capable of making a high molecular weight polyolefin. The process yields medium density and linear low density polyethylene having a bimodal molecular weight distribution and a melt index from about 0.10 to about 0.80. Films from the polyethylene have superior impact properties.

Polyethylene process

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.

Method for making polyolefins

A high molecular weight, medium density polyethylene (HMW, MDPE) is disclosed. The polyethylene comprises from about 85 to about 98 wt % of recurring units of ethylene and about 2 to about 15 wt % of a C &agr;-olefin. It has a density from about 0.92 to about 0.944 g/cc, a melt index MI from about 0.01 to about 0.5 dg/min, and a melt flow ratio MFR from about 50 to about 300. It has a multimodal molecular weight distribution comprising a high molecular weight component and a low molecular weight component. The low molecular weight component has an MI from about 50 to about 600 dg/min and a density from about 0.94 to about 0.97 g/cc. A process for making the medium density polyethylene is also disclosed. The process uses a Ziegler catalyst and applies multiple reaction zones.

High molecular weight, medium density polyethylene

An ethylene polymerization process is disclosed. The process uses a single-site catalyst that contains a boraaryl ligand. It comprises supporting the catalyst, forming a slurry of the supported catalyst in an organic solvent, mixing the catalyst slurry with trialkyl aluminum compound, and polymerizing ethylene in the presence of the trialkyl aluminum-treated catalyst slurry. The process gives polyethylene having a controlled long-chain-branch index.

Ethylene polymerization process

An ethylene polymerization process is disclosed. The polyethylene has a long-chain-branching index (LCBI) of 1 or greaster. The process uses a single-site catalyst that contains a boraaryl ligand. The catalyst is alkylated with triisobutyl aluminum.

A high molecular weight, medium density polyethylene (HMW, MDPE) is disclosed. The polyethylene comprises from about 85 to about 98 wt % of recurring units of ethylene and about 2 to about 15 wt % of a C -C &agr;-olefin. It has a density from about 0.92 to about 0.944 g/cc, a melt index MI from about 0.01 to about 0.5 dg/min, and a melt flow ratio MFR from about 50 to about 300. It has a multimodal molecular weight distribution comprising a high molecular weight component and a low molecular weight component. The low molecular weight component has an MI from about 50 to about 600 dg/min and a density from about 0.94 to about 0.97 g/cc. A process for making the medium density polyethylene is also disclosed. The process uses a Ziegler catalyst and applies multiple reaction zones.

A single-site olefin polymerization catalyst is described. The catalyst comprises an activator and an organometallic compound that includes a Group 3 to 10 transition or lanthanide metal, M, and a modified boraaryl ligand. We surprisingly found that the catalyst is more active in olefin polymerization compared to other catalysts containing non-modified boraaryl ligands. Most surprisingly, the supported catalyst gives polyolefins with a multimodal molecular weight distribution having separate components of distinct molecular weight.

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West Chester, OH, United States of America

Jean A Merrick-Mack