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Modified phosphinimine catalysts for olefin polymerization

  • US 9,221,935 B2
  • Filed: 08/19/2014
  • Issued: 12/29/2015
  • Est. Priority Date: 06/09/2011
  • Status: Active Grant
First Claim
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1. A gas phase olefin polymerization process wherein the process comprises adding a seed bed to a gas phase reactor prior to performing a polymerization reaction, wherein the seed bed comprises a polyethylene polymer which is produced by polymerizing ethylene and optionally an alpha olefin in a reactor with an olefin polymerization catalyst comprising:

  • i) a phosphinimine catalyst;

    ii) an inert support;

    iii) a cocatalyst; and

    iv) a catalyst modifier;

    wherein the catalyst modifier is present in from 0.25 to 6.0 weight percent based on the weight of i), ii) and iii) of the polymerization catalyst and comprises a compound having the formula;

    R1R2xN((CH2)nOH)y where R1 is a hydrocarbyl group having from 5 to 30 carbon atoms, R2 is hydrogen or a hydrocarbyl group having from 1 to 30 carbon atoms, x is 1 or 0, y is 1 when x is 1, y is 2 when x is 0, each n is independently an integer from 1 to 30 when y is 2, and n is an integer from 1 to 30 when y is 1;

    provided that the polyethylene polymer comprises at least 1 ppm of the catalyst modifier based on the weight of the polyethylene polymer which was originally present in the olefin polymerization catalyst.

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