Lubricant compositions stabilized by mixtures of diarylamine and hydroxydiarylamine antioxidants
Lubricant compositions comprising a lubricating oil and a mixture of one or more alkylated diarylamine and one or more alkylated hydroxydiarylamine exhibit excellent antioxidant and deposit control performance.
1. A lubricating oil composition comprising
a) a lubricating oil, and
b) a mixture of, based on the combined weight of i and ii,
i) from about 10 to about 90 wt % of one or more alkylated hydroxydiphenylamine of formula
wherein x is 0 or 1 and y is 0, 1, 2 or 3, provided that at least one of x and y is other than 0;
each R is independently C 1-24 alkyl, or C 4-24 alkyl substituted by one or more hydroxyl or interrupted by one or more oxygen atom,
wherein at least one carbon atom adjacent to the amine nitrogen is unsubstituted; and
ii) from about 10 to about 90 wt % of one or more alkylated diphenylamines of the formula X:
wherein x′ is 1 or 2 and y′ is 0, 1 or 2 and each R″ independently from each other is C 1-24 alkyl; and
wherein the mixture of b) is present in an amount of about 0.1 to about 5.0 wt %, based on the weight of the lubricating oil composition.
2. The lubricating oil composition according to claim 1 wherein the alkylated hydroxydiphenylamine is of the formula V.
3. The lubricating oil composition according to claim 1 wherein x is 0 or 1 and y is 1, 2 or 3.
4. The lubricating oil composition according to claim 1 wherein each R is independently C 1-24 alkyl.
5. The lubricating oil composition according to claim 1 wherein x is 0 or 1 and y is 1, 2 or 3 and each R is independently C 1-24 alkyl.
6. The lubricating oil composition according to claim 1 wherein x is 0 or 1 and y is 0, 1 or 2, provided that at least one of x and y is other than 0.
7. The lubricating oil composition according to claim 1 wherein each R″ in formula X, independently from each other, is C 4-18 alkyl.
8. The lubricating oil composition according to claim 1 wherein each R is independently C 4-24 alkyl or C 4-24 alkyl interrupted by one or more oxygen atom.
9. The lubricating oil composition according to claim 1 wherein the lubricating oil comprises one or more hydrocarbon base stocks.
10. The lubricating oil composition according to claim 1 wherein when y is 1, (R)y contains at least four carbon atoms.
11. The lubricating oil composition according to claim 2 wherein when y is 1, (R)y contains at least four carbon atoms.
12. The lubricating oil composition according to claim 6 wherein the alkylated hydroxydiphenylamine is of the formula V.
13. The lubricating oil composition of claim 8 wherein the alkylated hydroxydiphenylamine is of the formula V.
14. The lubricating oil composition according to claim 12 wherein when y is 1, (R)y contains at least four carbon atoms.
15. The lubricating oil composition according to claim 6 wherein x is 0 or 1 and y is 1 or 2.
16. The lubricating oil composition according to claim 8 wherein x is 0 or 1 and y is 1 or 2.