Lubricating composition with alkylated naphthylamine
A lubricating composition includes an oil of lubricating viscosity, an N-alkyl naphthylamine, and at least one ashless antioxidant selected from a diarylamine antioxidant, a phenolic antioxidant, and mixtures thereof. The lubricating composition has a phosphorus content of less than 0.15 weight percent. The combination of the N-alkyl naphthylamine and ashless antioxidant provides a beneficial effect on the basicity of the composition without negatively impacting seals performance.
1. A lubricating composition comprising:
an oil of lubricating viscosity, at least one ashless antioxidant, and an N-alkyl naphthylamine compound represented by the formula:
where R 1 is hydrogen,
R 2 is an alkyl group of 1 to 30 carbon atoms,
R 3 is an alkyl group of 1 to 30 carbon atoms, and
n is from 0-2;
a ratio of the at least one ashless antioxidant to the N-alkyl naphthylamine compound present in the lubricating composition being from 40:60 to 80:20, and
wherein the lubricating composition has a phosphorus content of less than 0.15 weight percent.
2. The lubricating composition of claim 1 , wherein R 2 is alkyl group of 1 to 24 carbon atoms.
3. The lubricating composition of claim 1 , wherein R 2 is alkyl group of at least 3 carbon atoms.
4. The lubricating composition of claim 1 , wherein the N-alkyl naphthylamine is represented by the formula:
5. The lubricating composition of claim 1 , wherein the N-alkyl naphthylamine is represented by the formula:
wherein R 2 is an alkyl group of 6 to 24 carbon atoms.
6. The lubricating composition of claim 1 , wherein the at least one ashless antioxidant is present is present in a total amount of at least 0.15 weight percent of the composition.
7. The lubricating composition of claim 1 , wherein the at least one ashless antioxidant comprises a diarylamine antioxidant.
8. The lubricating composition of claim 7 , wherein the diarylamine antioxidant is selected from phenylnaphthylamines of the general formula:
where each of R 7 , R 8 is selected from H and C 8 -C 24 alkyl groups and at least one of R 7 and R 8 is not H; and
alkylated diphenylamine antioxidant of the general formula:
where each of R 7 , R 8 , R 9 and R 10 , is selected from H and C 8 -C 24 alkyl groups, and wherein at least one of R 7 , R 8 , R 9 , and R 10 is not H.
9. The lubricating composition of claim 1 , wherein the ashless antioxidant comprises a phenolic antioxidant.
10. The lubricating composition of claim 9 , wherein the phenolic antioxidant is selected from the group consisting of C 7 -C 9 branched alkyl esters of 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-benzenepropanoic acid, 2-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol, 2,4-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 2-tert-butyl-4-methoxyphenol, 3-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butyl-4-alkylphenols, 2,6-di-tert-butyl-4-alkoxyphenols, 3,5-di-tert-butyl-4-hydroxybenzylmercaptooctylacetate, alkyl-3-(3, 5-d i-tert-butyl-4-hydroxyphenyl)propionates, 2,6-di-tert-butyl-a-dimethylamino-p-cresol, 2,2′-methylene-bis(4-alkyl-6-tert-butylphenol), bisphenols, polyphenols, p-t-butylphenol-formaldehyde condensates and p-t-butylphenol-acetaldehyde condensates.
11. The lubricating composition of claim 1 , further comprising an antiwear agent.
12. The lubricating composition of claim 1 , wherein the oil of lubricating viscosity is at least 40 weight percent of the lubricating composition.
13. A method of lubricating a mechanical device comprising supplying the lubricating composition of claim 1 to the device.
14. The lubricating composition of claim 1 , wherein the N-alkyl naphthylamine is present in an amount of at least 0.15 weight percent of the lubricating composition.
15. The lubricating composition of claim 1 , where in the N-alkyl naphthylamine is present in an amount of no more than 2.5 weight percent of the lubricating composition.
16. The lubricating composition of claim 1 , wherein the at least one ashless antioxidant is present in a total amount of no more than 5 weight percent of the composition.
17. The lubricating composition of claim 1 , further comprising an alkaline earth metal overbased detergent in an amount to deliver a total base number (TBN), as measured by ASTM D2896, of at least 2 mg KOH/g to the composition.
18. A method for improving the retention of total base number in a crankcase lubricating composition comprising an oil of lubricating viscosity, the method comprising:
incorporating an N-alkyl naphthylamine and at least one ashless antioxidant in the lubricating composition, the N-alkyl naphthylamine compound being represented by the formula:
where R 1 is hydrogen,
R 2 is an alkyl group of 1 to 30 carbon atoms,
R 3 is an alkyl group of 1 to 30 carbon atoms, and
n is from 0-2;
whereby a ratio of the at least one ashless antioxidant to the N-alkyl naphthylamine compound present in the lubricating composition is from 40:60 to 80:20, and the lubricating composition has a phosphorus content of less than 0.15 weight percent.