Viscosity index improver and lube oil containing the same

  • US 20030104955A1
  • Filed: 08/07/2002
  • Published: 06/05/2003
  • Est. Priority Date: 04/06/2001
  • Status: Active Grant
First Claim
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1. A viscosity index improver, which comprises a polymer (A1) having a solubility parameter of 8.6-9.4, a crystallizing initiation temperature of −

  • 15°

    C. or less, and a steric hindrance factor (F) of 0-13, said factor F being defined by the following equation;

    F=4X+Y



    (1) wherein X and Y represent the total atom numbers at the 6th position and the 7th position, respectively, in the side chains, counted from the backbone;

    said polymer (A1) having a weight-average molecular weight of 5,000-2,000,000 and comprising units of at least one monomer selected from the group consisting of;

    (a) a monomer represented by the general formula;



    wherein R0 is hydrogen atom or methyl group, R is a C1-40alkyl group, n is 0 or an integer of 1-20 giving 0-10 on average, A is an alkylene group containing 2-4 carbon atoms, plural A'"'"'s in case of n being at least 2 are the same or different, and the polyoxyalkylene moiety (A0)n in case of the plural A'"'"'s being different comprises random-wise or block-wise distributed oxyalkylene groups, (b) an alkyl alkenyl ether, (c) an alkenyl carboxylate, and (d) a nitrogen-containing unsaturated monomer.

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