Lubricant composition
A lubricating oil composition containing a phosphite ester derivative (A) having at least one alkyl group having 1 to 20 carbon atoms in which one —CH 2 — group is substituted with a —S— group, and a thiadiazole derivative (B). A method of lubricating an electric drive unit with the lubricating oil composition and an electric drive unit including the lubricating oil composition.
1 . A lubricating oil composition, comprising:
a base oil having a content in a range of 94.00% by mass to 94.88% by mass based on a total amount of the lubricating oil composition;
a phosphite ester derivative having at least one alkyl group having 1 or more and 20 or less carbon atoms in which one —CH 2 — group is substituted with a —S— group;
a thiadiazole derivative; and
a polymethacrylate having a content of 0.10% by mass or less based on the total amount of the lubricating oil composition,
wherein the phosphite ester derivative includes a compound of formula (A1) and a compound of formula (A2),
where each of R A11 , R A21 , and R A22 is independently an alkyl group having 8 carbon atoms, and each of a A11 , a A21 , and a A22 is independently an integer of 2, the phosphite ester derivative has a content in a range of 0.30% by mass to 1.06% by mass based on the total amount of the lubricating oil composition, and the compound of the formula (A1) has a content in a range of 89% by mass to 90% by mass based on a total amount of the phosphite ester derivative, and the thiadiazole derivative comprises a thiadiazole ring and a side chain attached to the thiadiazole ring and having a branched alkyl group, the thiadiazole derivative includes a compound of formula (B1),
where each of R B11 and R B12 is independently a —X B41 —R B41 group, where X B41 is —S—S—, and R B41 is a branched alkyl group having 9 carbon atoms,
wherein the compound of the formula (A1) has a content in a range of 0.27% by mass to 0.95% by mass based on the total amount of the lubricating oil composition, and the compound of the formula (A2) has a content in a range of 0.03% by mass to 0.11% by mass based on the total amount of the lubricating oil composition,
wherein the compound of the formula (B1) has a content of 0.20% by mass to 0.80% by mass based on the total amount of the lubricating oil composition,
wherein the base oil includes at least one selected from the group consisting of 60N hydrocracked mineral oil, 70N hydrocracked mineral oil, 100N hydrocracked mineral oil and 150N hydrocracked mineral oil,
wherein the 60N hydrocracked mineral oil has a content in a range of 20% by mass to 75.60% by mass based on the total amount of the lubricating oil composition, the 70N hydrocracked mineral oil has a content in a range of 0% by mass to 1.17% by mass based on the total amount of the lubricating oil composition, the 100N hydrocracked mineral oil has a content in a range of 0% by mass to 74.00% by mass based on the total amount of the lubricating oil composition, and the 150N hydrocracked mineral oil has a content in a range of 0% by mass to 18.50% by mass based on the total amount of the lubricating oil composition.
2 . The lubricating oil composition according to claim 1 , wherein the phosphite ester derivative has a phosphorus atom-equivalent content, X AP ppm by mass, in a range of 50 ppm by mass to 10,000 ppm by mass based on the total amount of the lubricating oil composition.
3 . The lubricating oil composition according to claim 2 , wherein the thiadiazole derivative has a sulfur atom-equivalent content, X BS ppm by mass, in a range of 100 ppm by mass to 10,000 ppm by mass based on the total amount of the lubricating oil composition.
4 . The lubricating oil composition according to claim 3 , wherein 0.05≤X AP /X BS ≤5.00.
5 . The lubricating oil composition according to claim 1 , wherein a sum of a sulfur atom-equivalent content of the phosphite ester derivative and a sulfur atom-equivalent content of the thiadiazole derivative is in a range of 100 ppm by mass to 10,000 ppm by mass based on the total amount of the lubricating oil composition.
6 . A method of lubricating an electric drive unit, comprising:
applying the lubricating oil composition of claim 1 .
7 . An electric drive unit, comprising the lubricating oil composition of claim 1 .
8 . The lubricating oil composition according to claim 1 , wherein the thiadiazole derivative has a content in a range of 0.20% by mass to 0.80% by mass based on the total amount of the lubricating oil composition.
9 . The lubricating oil composition according to claim 1 , wherein the compound of the formula (A1) has a content of 0.27% by mass based on the total amount of the lubricating oil composition, and the compound of the formula (A2) has a content of 0.03% by mass based on the total amount of the lubricating oil composition.
10 . The lubricating oil composition according to claim 9 , wherein the content of the phosphite ester derivative is 0.30%.
11 . The lubricating oil composition according to claim 1 , wherein the lubricating oil composition has an FZG value of 7-9 measured according to ASTM D5182, a copper elution amount of 14-46 ppm by mass measured according to JIS K-2514 and ASTM D4915, and a volume resistivity of 1.90-4.00×10 7 Ωm measured according to JIS C 2101.
12 . The lubricating oil composition according to claim 1 , wherein the lubricating oil composition has an FZG value of 7-8 measured according to ASTM D5182, a copper elution amount of 18-46 ppm by mass measured according to JIS K-2514 and ASTM D4915, and a volume resistivity of 2.80-3.50×10 7 Ωm measured according to JIS C 2101.