Lubricating oil composition

  • US 10,472,583 B2
  • Filed: 09/18/2015
  • Issued: 11/12/2019
  • Est. Priority Date: 09/19/2014
  • Status: Active Grant
First Claim
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1. A lubricating oil composition, comprising:

  • a viscosity index improver; and

    a base oil;

    wherein;

    the viscosity index improver comprises a comb-shaped polymer;

    the comb-shaped polymer has a molecular weight distribution Mw/Mn of 1.01 or greater and less than 2.00, where Mw represents a weight average molecular weight of the comb-shaped polymer, and Mn represents a number average molecular weight of the comb-shaped polymer;

    the comb-shaped polymer has a weight average molecular weight of 330,000 to 600,000;

    a content of the comb-shaped polymer in the viscosity index improver is 60 to 100 mass % based on a total amount of a solid component in the viscosity index improver;

    the comb-shaped polymer is present in an amount of 0.90 to 4.00 mass % based on the total mass of the composition;

    the viscosity index improver has a shear stability index of 30 or less;

    the base oil comprises a Group 3 mineral oil;

    the base oil has a kinematic viscosity at 100°

    C. in mm2/s of 2.0 to 7.0;

    the base oil is present in an amount of 70 to 95 mass % based on the total mass of the composition;

    the lubricating oil composition has a high temperature high shear viscosity at 150°

    C. of 1.6 to 2.9 mPa·

    s; and

    a ratio of a kinematic viscosity at 40°

    C. in mm2/s of the lubricating oil composition to the high temperature high sheer viscosity at 150°

    C. of the lubricating oil composition is 8.00 to 12.4.

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