Stabilizing compositions for lubricants

Abstract

A lubricant composition is disclosed that comprises lubricating oil and a mixture of at least two antioxidants, the first antioxidant being a substituted diphenylamine and/or a heterocyclic amine and the second antioxidant being a substituted phenol. Also disclosed is a method of increasing the oxidation stability of a lubricating oil comprising adding thereto at least two antioxidants, the first antioxidant being a substituted diphenylamine and/or a heterocyclic amine and the second antioxidant being a substituted phenol.

Description

Claims

1. A lubricant composition comprising: (A) at least one lubricating oil selected from the group consisting of natural and synthetic lubricating base oils;(B) at least one first antioxidant selected from the group consisting of: (1) diphenylamines represented by the formula

2. The composition of claim 1 wherein at least one of R1 and R2 is an alkyl group of 1 to 12 carbon atoms.

3. The composition of claim 1 wherein at least one of R1 and R2 is α-alkyl styryl wherein the alkyl group is of 1 to 4 carbon atoms.

4. The composition of claim 1 wherein at least one of R1 and R2 is α-alkyl styryl wherein the alkyl group is methyl.

5. The composition of claim 1 wherein n of the heterocyclic amines is an integer from 1 to 10, isomers of methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, and mixtures thereof.

6. The composition of claim 1 wherein the alkyl moieties of the phenolic rings are of 1 to 10 carbon atoms and isomers of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl.

7. The composition of claim 1 wherein the aminic and phenolic antioxidant additives are blended with additional component selected from the group consisting of Group I, Group II, Group III, Group IV base stocks, triaryl phosphate esters, tri-alkyl phosphate esters, alkyl mono-acide phosphates, alkyl di-acid phosphates, alkyl phosphites, aryl phosphites, liquid phenolic antioxidants, aminic antioxidants, carboxylate esters, aromatic hydrocarbons, and liquid glycols.

8. A lubricant composition comprising: (A) at least one lubricating oil selected from the group consisting of natural and synthetic lubricating base oils;(B) at least one first antioxidant selected from the group consisting of: (1) diphenylamines represented by the formula

9. The composition of claim 8 wherein the sulfur-containing alkylated phenol component is selected from the group of consisting of:

10. A method of increasing the oxidation stability of a lubricant comprising adding thereto (A) at least one first antioxidant selected from the group consisting of: (1) diphenylamines represented by the formula