Equistar Chemicals, LP

Occidental Chemical Corporation

Philip J Garrison

Paula L Nygard

Mark P Mack

Lawrence R Wallace

Leonard V Cribbs

Jean A Merrick-Mack

Bradley P Etherton

Harilaos Mavridis

Sameer D Mehta

James H Meas

Danny L Wise

James H Meas, Jr

Michael W Lynch

Charles S Holland

Linda N Winslow

Jeffrey Charles Haley

Stephen M Imfeld

Jeffrey S Borke

James Ronald Clark

Everett O Lewis

Jeffrey C Haley

Disclosed is a multimodal, high density, homopolyethylene barrier resin. The resin is preferably made by a multistage process. The process comprises a first stage in which ethylene is homopolymerized in the presence of a Ziegler-Natta catalyst, organoaluminum cocatalyst, alkoxysilane modifier, and hydrogen. The reaction mixture from the first stage is devolatilized to remove all or substantially all of the hydrogen. The polymerization continues in a second stage wherein ethylene is added to the devolatilized reaction mixture to produce the barrier resin. The barrier resin provides films with improved barrier properties.

Preparation of multimodal, high density, ethylene homopolymer barrier resins and films

A two-stage cascade polymerization process for the production of multimodal polyethylene film resins with improved bubble stability is provided. The process comprises polymerizing ethylene or a mixture of ethylene and a C&#x3b1;-olefin in two reactors arranged in series using a mixed single-site catalyst comprised of a bridged and a non-bridged indenoindolyl transition metal complex to form a multimodal polyethylene resin comprised of a lower molecular weight, higher density component and a higher molecular weight, lower density component.

Process for the preparation of multimodal polyethylene resins

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

Resins comprising a relatively high-density, low-molecular-weight polyethylene component and a relatively low-density, high-molecular-weight ethylene copolymer component and methods of making the resins are disclosed. The rheological polydispersity of the high-density component exceeds that of either the resin or the low-density component. The resins are valuable for making films, sheets, coatings, pipes, fibers, and molded articles having a favorable balance of good stiffness and excellent environmental stress crack resistance.

Polymer resins with improved environmental stress crack resistance

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

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 process for producing a polyethylene film composition, comprising melt extruding a linear copolymer of ethylene and at least one other olefin having from 3 to 8 carbon atoms, said linear copolymer having a bimodal distribution comprising a high molecular weight fraction having a weight average molecular weight of at least 600,000 and a low molecular weight fraction having a weight average molecular weight of less than 20,000 at a temperature of from 195 to 285.degree. C. in the presence of oxygen in an amount of from about 0.5 to about 6% by volume to improve bubble stability without any significant reduction in tear strength of film produced from said melt extruded linear copolymer.

Process for producing polyethylene film composition having broad

A polyethylene film composition characterized as having a broad molecular weight distribution, Mw/Mm 15, a density of 0.920 to 0.970 g/cc, a melt flow index (190.degree. C./2.16 kg) of 0.01 to 0.2 g/10 min., the polyethylene film composition being produced by melt extruding a linear copolymer at a temperature of at least 180.degree. C. in the presence of an amount of a free radical initiator sufficient to improve bubble stability without any significant reduction in the tear strength of film produced from the composition as compared with film produced from the linear copolymer that has not been treated with the free radical initiator.

Polyethlene film composition having broad molecular weight distribution

Disclosed is a method of dispersing a tacky additive in a solution of a polymer, particularly a polyolefin. A dispersion composition prepared by adding the additive to a slurry of a non-polar solvent and an insoluble, infusible, non-reactive dispersant is added to the polymer solution. This prevents the additive from sticking to the vessel walls and the impeller or agglomerating.

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Houston, TX, United States of America

Philip J Garrison