Lubricating oil composition for shock absorber

Patent metadata

Field	Value
Publication number	US-9688941-B2
Application number	US-201414910883-A
Country	US
Kind code	B2
Filing date	Aug 25, 2014
Priority date	Aug 23, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

Provided is a lubricating oil composition for a shock absorber, which realizes excellent riding comfort in low-temperature and high-temperature environments and can suppress worsening of riding comfort with time, which is caused by evaporation and shearing of the lubricating oil. The lubricating oil composition for a shock absorber contains (A) a base oil having a pour point of lower than −40° C. and a kinematic viscosity at 80° C. of from 2.0 to 2.7 mm 2 /s, (B-1) from 1 to 15% by mass of a polymethacrylate having a weight-average molecular weight of from 10,000 to less than 100,000, and (B-2) from 0.1 to 5% by mass of a polymethacrylate having a weight-average molecular weight of from 100,000 to 200,000.

First claim

The invention claimed is:

1. A lubricating oil composition, comprising:
(A) a base oil having a pour point of lower than −40° C., a kinematic viscosity at 80° C. of from 2.0 to 2.7 mm 2 /s and a density at 15° C. of from 0.80 to 0.83 g/cm 3 ;
(B-1) from 1 to 7.67% by mass of a polymethacrylate having a weight-average molecular weight of from 10,000 to less than 50,000; and
(B-2) from 0.1 to 5% by mass of a polymethacrylate having a weight-average molecular weight of from 140,000 to 200,000,
which comprises from 6.0 to 9.8% by mass in a total amount of the component (B-1) and the component (B-2) in the lubricating oil composition,
wherein the lubricating oil composition has a NOACK value of 12 wt % or less; a viscosity reduction rate in the ultrasonic shearing stability test of 18% or less; and a BF viscosity at −40° C. of 600 mPa·s or less.

2. The lubricating oil composition according to claim 1 , wherein the polymethacrylate of the component (B-1) and/or the component (B-2) is a nondispersive polymethacrylate.

3. The lubricating oil composition according to claim 1 , wherein the high-temperature high-shear viscosity at 80° C. of the lubricating oil composition is 4.2 mPa·s or more.

4. The lubricating oil composition according to claim 1 , wherein the composition is suitable for cars.

5. The lubricating oil composition according to claim 1 , wherein the total amount of the polymethacrylate (B-1) and the polymethacrylate (B-2) is from 8.4 to 9.8 mass %.

6. The lubricating oil composition according to claim 1 , having a NOACK value of 8.0-11.0 wt %.

7. The lubricating oil composition according to claim 1 , having a shearing stability of from 11 to 16.

8. The lubricating oil composition according to claim 1 , having a BF viscosity at −40° C. of from 520 to 600 mPa·s.

9. The lubricating oil composition according to claim 1 , wherein the poymethacrylate (B-1) has a weight average molecular weight of from 10,000 to 30,000.

10. The lubricating oil composition according to claim 1 , wherein the base oil is a mineral oil.

11. The lubricating oil composition according to claim 1 , having a NOACK value of 8.0-11.0 wt %; a shearing stability of from 11 to 16; a BF viscosity at −40° C. of from 520 to 600 mPa·s; and wherein the polymethacrylate (B-1) has a weight average molecular weight of from 10,000 to 30,000.

12. The lubricating oil composition according to claim 1 , wherein the amount of the polymethacrylate (B-1) is from 4 to 10% by mass and the amount of the polymethacrylate (B-2) is from 1 to 3% by mass.

Assignees

• Idemitsu Kosan Co

Inventors

• Sakanoue Shuichi
• Aoki Aya

Classifications

• C10M169/041 Primary

  the additives being macromolecular compounds only · CPC title

• C10M101/02

  Petroleum fractions · CPC title

• C10M2207/2805

  used as base material · CPC title

• C10M2209/084

  Acrylate; Methacrylate · CPC title

• C10M105/06

  aromatic · CPC title