Lubricant composition
The present invention provides a lubricating oil composition comprising a lubricating base oil, and at least one ester additive selected from a first ester that is a fatty acid 3,4-epoxycyclohexyl alkyl ester and a second ester that is a 3,4-epoxycyclohexyl carboxylic acid alkyl ester, wherein a content of the ester additive is 0.01 to 5.0% by mass based on the total mass of the lubricating oil composition.
1. A lubricating oil composition comprising:
a lubricating base oil; and
at least one ester additive selected from a first ester that is a fatty acid 3,4-epoxycyclohexyl alkyl ester and a second ester that is a 3,4-epoxycyclohexyl carboxylic acid alkyl ester,
wherein a content of the ester additive is 0.01 to 5.0% by mass based on the total mass of the lubricating oil composition.
2. The lubricating oil composition according to claim 1 , wherein a constituent fatty acid of the first ester is a branched fatty acid having 5 to 20 carbon atoms, and an alkyl group contained in an ester group of the second ester is a branched alkyl group having 5 to 20 carbon atoms.
3. The lubricating oil composition according to claim 1 , wherein the first ester has a structure containing a 1,2-epoxycyclohexane ring, a residue obtained by removing a hydrogen atom from a carboxyl group of the fatty acid, and a linear alkylene group having 1 to 4 carbon atoms, wherein the residue is bound to a carbon atom at 4- or 5-position of the 1,2-epoxycyclohexane ring via the linear alkylene group.
4. The lubricating oil composition according to claim 1 , wherein a kinematic viscosity at 40° C. of the lubricating oil composition is 5 to 1000 mm 2 /s.
5. The lubricating oil composition according to claim 1 , wherein the lubricating base oil is at least one selected from a mineral oil-based base oil, a synthetic oil-based base oil and an animal and vegetable oil-based base oil.
6. The lubricating oil composition according to claim 5 , wherein the synthetic oil-based base oil is at least one selected from an ester and an ether.
7. A lubricating oil composition for a refrigerating machine, consisting of the lubricating oil composition according to claim 6 .
8. The lubricating oil composition for a refrigerating machine according to claim 7 , wherein the synthetic oil-based base oil is at least one selected from a polyol ester, a polyalkylene glycol and a polyvinyl ether.
9. The lubricating oil composition for a refrigerating machine according to claim 8 , being used together with a refrigerant comprising an unsaturated hydrofluorocarbon.
10. The lubricating oil composition of claim 1 , wherein the at least one ester additive is the first ester.
11. The lubricating oil composition of claim 1 , wherein the at least one ester additive is the second ester.
12. The lubricating oil composition of claim 1 , wherein
the first ester is represented by the following formula (2):
where R 6 represents a hydrocarbon group having 4 to 19 carbon atoms and n represents an integer of 1 to 4,
and the second ester is represented by the following formula (3):
where R 7 represents an alkyl group having 5 to 20 carbon atoms.
13. The lubricating oil composition of claim 12 , wherein the at least one ester additive is the first ester.
14. The lubricating oil composition of claim 12 , wherein the at least one ester additive is the second ester.
15. The lubricating oil composition of claim 1 , comprising the first and second ester.