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High activity polyethylene catalyst prepared from an alcohol and silicon tetrachloride

  • US 5,561,091 A
  • Filed: 05/02/1995
  • Issued: 10/01/1996
  • Est. Priority Date: 11/18/1993
  • Status: Expired due to Term
First Claim
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1. A catalyst composition for copolymerization of ethylene with an alpha-olefin, to produce a resin product of narrow molecular weight distribution, and having a density of less than 0.94 g/cc;

  • wherein the catalyst composition is prepared by a process which comprises the steps of;

    (i) contacting a solid, porous carrier having reactive OH groups in a non-polar liquid with dibutylmagnesium to form a product of step (i) which contains said carrier and incorporated therein a source of magnesium, wherein said dibutylmagnesium is soluble in said non-polar liquid;

    wherein, the ratio of the number of moles of said dibutylmagnesium to the number of moles of said OH groups is from about 1.1 to about 2.5;

    (ii) introducing into the liquid containing said product of step (i) a mixture of SiCl4 and an alcohol R"OH in which R" is selected from the group consisting of methyl, ethyl, propyl, n-butyl, pentyl, and n-octyl, thereby to form a slurry of step (ii) wherein the mixture has a molar ratio of R"OH to SiCl4 of 2.00 to 6.00;

    wherein the molar ratio of SiCl4 to Mg is 0.40 to 1.40; and

    wherein the molar ratio of R"OH to Mg is at least about 1.32.(iii) contacting said slurry of step (ii) with at least one transition metal compound in a non-polar liquid medium, the number of moles of said transition metal compound being in excess of the number of moles of OH groups on said carrier prior to reaction with said dibutylmagnesium in step (i), said transition metal compound being soluble in said non-polar liquid, and said dibutylmagnesium contacted carrier being substantially insoluble in said liquid medium, whereby a reacted form of the transition metal becomes supported on said carrier to form a step (iii) precursor; and

    (iv) contacting the step (iii) precursor with an activating amount of trialkylaluminum R'"'"'3 Al, in which R'"'"' is an alkyl group of 1 to 10 carbon atoms.

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