Lubricating oil composition, and precision reduction gear using same

Patent metadata

Field	Value
Publication number	US-10647940-B2
Application number	US-201716086409-A
Country	US
Kind code	B2
Filing date	Mar 31, 2017
Priority date	Mar 31, 2016
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

Provided are a lubricating oil composition containing a base oil and a specific thiophosphate compound (A) and not substantially containing a molybdenum-based, and a precision reduction gear using the lubricating oil composition. The lubricating oil composition and the precision reduction gear using it exhibit excellent wear resistance and can prevent sludge generation in a broad range of contact pressures ranging from high to low.

First claim

The invention claimed is:

1. A lubricating oil composition, comprising, based on the total amount of the lubricating oil composition:
a base oil;
from 0.1% by mass or more to 1.0% by mass or less of a thiophosphate compound (A) of formula (I):

wherein R 1 , R 2 and R 3 each independently represent an aryl group having 6 to 12 ring carbon atoms, and the aryl group may be substituted with an alkyl group having 1 to 3 carbon atoms; and

from 0.1% by mass or more to 1.5% by mass or less of a phosphate compound (B) not comprising a sulfur atom, wherein the compound (B) is not an amine salt of a phosphate compound not comprising a sulfur atom,
wherein the lubricating oil composition does not substantially comprise a molybdenum-based compound, and
wherein the molybdenum atom-equivalent content of the molybdenum-based compound is less than 100 ppm by mass based on the total amount of the lubricating oil composition.

2. The lubricating oil composition according to claim 1 , wherein the component (A) is a thiophosphate compound (A1) having formula (II):

wherein R 4 , R 5 and R 6 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

3. The lubricating oil composition according to claim 1 , wherein the content of the component (B) is, based on the total amount of the lubricating oil composition, from 0.2% by mass or more to 1.2% by mass or less.

4. The lubricating oil composition according to claim 1 , further comprising a sulfur-based compound (C) containing 2 or more sulfur atoms in the molecule and not containing a phosphorus atom.

5. The lubricating oil composition according to claim 4 , wherein the content of the component (C) is, based on the total amount of the lubricating oil composition, 0.01% by mass or more and 1% by mass or less.

6. The lubricating oil composition according to claim 1 , having a kinematic viscosity at 40° C. of 40 mm 2 /s or more.

7. The lubricating oil composition according to claim 1 , which is adapted to function as a lubricating oil composition for lubricating precision reduction gears.

8. A precision reduction gear, comprising the lubricating oil composition of claim 1 .

9. The precision reduction gear of claim 8 , is incorporated in industrial robots.

10. A method for producing a lubricating oil composition, the method comprising blending a base oil, a thiophosphate compound (A) of formula (I), and a phosphate compound (B) not comprising a sulfur atom, but not comprising blending a molybdenum-based compound:

to obtain the lubricating oil composition,
wherein, in formula (I), R 1 , R 2 and R 3 each independently represent an aryl group having 6 to 12 ring carbon atoms, and the aryl group may be substituted with an alkyl group having 1 to 3 carbon atoms,
wherein the molybdenum atom-equivalent content of the molybdenum-based compound is less than 100 ppm by mass based on the total amount of the lubricating oil composition, and
wherein the content of the thiophosphate compound (A) is, based on the total amount of the lubricating oil composition, 0.1% by mass or more and 1.0% by mass or less,
wherein the content of the phosphate compound (B) is, based on the total amount of the lubricating oil composition, 0.1% by mass or more and 1.5% by mass or less, and
wherein the compound (B) is not an amine salt of a phosphate compound not comprising a sulfur atom.

11. The lubricating oil composition according to claim 1 , wherein the molybdenum atom-equivalent content of the molybdenum-based compound is less than 10 ppm by mass based on the total amount of the lubricating oil composition.

12. The lubricating oil composition according to claim 1 , wherein the molybdenum atom-equivalent content of the molybdenum-based compound is less than 5 ppm by mass based on the total amount of the lubricating oil composition.

Assignees

• Idemitsu Kosan Co

Inventors

• Ono Takuya

Classifications

• C10N2040/06

  Instruments or other precision apparatus, e.g. damping fluids · CPC title

• C10M2205/0245

  used as base material · CPC title

• C10M2223/047

  Thioderivatives not containing metallic elements · CPC title

• C10M137/04

  Phosphate esters · CPC title

• C10N2040/04

  Oil-bath; Gear-boxes; Automatic transmissions; Traction drives · CPC title