Lubricating oil composition
AssigneeIdemitsu Kosan Co., Ltd.
InventorToshimasa Utaka
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Abstract
The present invention provides a lubricating oil composition including a viscosity index improver (A) containing a comb-shaped polymer and having an SSI (shear stability index) of 30 or less together with a base oil, wherein an HTHS viscosity (high temperature high shear viscosity) at 150° C. (T150) is 1.6 to 2.9 mPa·s, and a ratio of a kinematic viscosity at 40° C. (V40) [mm2/s] to the HTHS viscosity at 150° C. (T150) [mPa·s] (V40/T150) is 12.4 or less. The lubricating oil composition of the present invention is excellent in fuel consumption reducing properties in a low-temperature region assuming the time of starting an engine while making various properties, such as a viscosity, etc., in a high-temperature region assuming the time of high-speed operation of an engine favorable.
Claims17
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.
A method for producing a lubricating oil composition, the method comprising:
- blending a base oil with a viscosity index improver to obtain the lubricating oil composition;
- 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 of the lubricating oil composition at 40° C. mm2/s to the high temperature high sheer viscosity of the lubricating oil composition at 150° C. is 8.00 to 12.4.
Dependencies are inferred from the claim text.