Equistar Chemicals, LP

Debra L Beran

Shaotian Wang

Mark P Mack

Giampiero Morini

Harilaos Mavridis

Barbara M Tsuie

Joachim T M Pater

William J Sartain

Edward S Vargas

Anil W Saraf

Jeffrey R Golden

Norma J Maraschin

Joachim T Pater

Disclosed is a process for making a linear low density polyethylene (LLDPE) having low gels. The process comprises copolymerizing ethylene with one or more C&#x3b1;-olefins to produce an LLDPE resin which has a gel defect area less than 25 ppm. The copolymerization is performed in the presence of a Ziegler-Natta catalyst which comprises an MgClsupport, a Ti(IV) complex, and a cyclic ether as an internal electron donor. The Ziegler-Natta catalyst has an Mg/Ti molar ratio greater than or equal to 7.

Preparation of LLDPE resins and films having low gels

A method of modifying a tubular low density polyethylene (LDPE) is disclosed. In the method ethylene is polymerized with a free radical initiator in a high pressure reactor to form an LDPE. The LDPE is then reacted with a free radical initiator to produce a modified polyethylene. The modified polymer has an increased long chain branching index as indicated by the increase in the gel permeation chromatography branching index.

Modifying tubular LDPE with free radical initiator

Methods for making polyolefins are disclosed. One method comprises polymerizing an olefin in the presence of a catalyst system comprising a single-site complex, an agglomerated metal oxide/clay support-activator, and an ionic borate. Including an ionic borate with the support-activator provides an unexpected boost in catalyst activity and gives polyolefins with high molecular weight and improved comonomer incorporation. In another method of the invention, an olefin is polymerized in the presence of an indenoindolyl metal alkylated complex and an agglomerated metal oxide/clay support-activator. Use of alkylated indenoindolyl complexes with the support-activators provides improved activity compared with metal halides.

Olefin polymerization methods

A supported olefin polymerization catalyst system and a method of making it are disclosed. The catalyst system comprises: (a) a support having mean particle size less than about 30 microns chemically treated with alumoxane; (b) an organometallic complex comprising a Group 3 to 10 transition or lanthanide metal, M, and at least one indenoindolyl ligand that is &pgr;-bonded to M; and (c) an activator. Chemical treatment with alumoxane and support mean particle size less than 30 microns are key to making supported indenoindolyl containing catalysts having high activity.

Supported olefin polymerization catalysts

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Cincinnati, OH, United States of America

Debra L Beran