Equistar Chemicals, LP

Kenneth J Klug

Shaotian Wang

Michael W Lynch

Gregory G Hlatky

Wallace W Yau

Jean A Merrick-Mack

Sebastian Joseph

A high-temperature solution process for making an ethylene polymer blend having a controlled degree of long-chain branching is disclosed. Ethylene is polymerized in the presence of a first Ziegler-Natta catalyst comprising titanium, magnesium, and aluminum in the absence of hydrogen to produce a first ethylene polymer component having substantial long-chain branching. A second ethylene polymer component having little or no long-chain branching is also prepared. Both polymerizations are performed at a temperature from 140&#xb0; C. to 250&#xb0; C. The first and second ethylene polymer components are combined to give a polymer blend. The degree of long-chain branching in the blend is controlled by adjusting the relative amounts of the first and second ethylene polymer components. The invention enables the preparation of valuable products having a pre-determined degree of long-chain branching using readily available Zeigler-Natta catalysts, commercially practiced techniques, and conventional equipment.

Process for making ethylene polymer blends with controlled long-chain branching

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

A process for polymerizing ethylene is disclosed. The process comprises polymerizing ethylene in a slurry reaction in the presence of a catalyst system which comprises an activator and an indenoindolyl transition metal complex on a support material. The catalyst system is slurried with an inert solvent prior to addition to the reactor. The process provides polyethylene with good bulk density.

Olefin polymerization process

Ethylene and optional comonomers are polymerized in the presence of an organozinc compound and a catalyst system to produce an ethylene polymer. The catalyst system comprises a bridged indenoindolyl Group 3-10 transition metal complex and an activator. The organozinc compound is used in an amount effective to increase the polymer bulk density compared with that observed in the absence of the organozinc compound. The organozinc compound can also narrow the particle size distribution of the polymer and the wt. % of polyolefin chunks produced. The operability of processes utilizing bridged indenoindolyl metal complexes is enhanced while maintaining desirably high polyolefin molecular weights.

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Cincinnati, OH, United States of America

Kenneth J Klug