Color-stable transmission fluid compositions
The present disclosure describes transmission fluid compositions, additive packages, and methods for lubricating a transmission, particularly transmission fluid compositions having color stability that are able to meet or exceed vehicle transmission fluid specifications for different makes of vehicles. The transmission fluid composition contains a base oil and an additive composition having at least one thiadiazole compound the selected from compounds of the Formulas (I)-(II): wherein n is 1-5; R 1 is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms; and R 2 is a hydrogen or is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms, wherein the transmission fluid composition is adapted for use in a transmission.
1. A transmission fluid composition comprising
about 50% to about 99% by weight of a base oil, based on the total weight of the transmission fluid composition and an additive composition comprising one of:
(a) a reaction product of thiadiazole of one of the formulae (III) and (IV):
wherein R 1 is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms; and a thiol of the formula R 3 —SH, wherein R 3 is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms, and optionally an additional sulfur source; and
(a) at least one compound of the Formulas (I)-(II):
wherein n is 1-5; R 1 is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms; and R 2 is hydrogen or a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms; and the transmission fluid composition is adapted for use in a transmission.
2. The transmission fluid composition as claimed in claim 1 wherein the additive composition comprises at least one compound of the Formula (I).
3. The transmission fluid composition as claimed in claim 1 wherein the additive composition comprises at least one compound of the Formula (II).
4. The transmission fluid composition as claimed in claim 1 , wherein the additive composition comprises at least one compound of the Formula (I) and at least one compound of the Formula (II).
5. The transmission fluid composition of claim 1 , wherein R 1 is an alkyl group having 1-10 carbon atoms and n is 2.
6. The transmission fluid composition of claim 5 , wherein n is 2 and R 2 is a hydrocarbyl group having 5-15 carbon atoms.
7. The transmission fluid composition of claim 6 , wherein n is 2 and R 2 is a hydrocarbyl group having 8-12 carbon atoms.
8. The transmission fluid composition of claim 7 , wherein n is 2 and R 2 is a hydrocarbyl group having 8-12 carbon atoms and R 1 is a methyl group.
9. The transmission fluid composition of claim 1 , having a change in color absorption ΔL* of negative 12 to 0, wherein ΔL* is measured with a spectrophotometer at 150° C. for 72 hours, at a content of at least 0.15 wt. % of the at least one thiadiazole compound; and wherein ΔL* is measured by the formula ΔL*=L* aged fluid −L* fresh fluid .
10. The transmission fluid composition of claim 1 , having a change in color absorption ΔL* of negative 11 to negative 0.5, wherein ΔL* is measured with a spectrophotometer at 150° C. for 72 hours, at a content of at least 0.15 wt. % of the at least one thiadiazole compound; and wherein ΔL* is measured by the formula ΔL*=L* aged fluid −L* fresh fluid .
11. The transmission fluid composition of claim 1 , having a change in color absorption ΔL* of negative 10 to negative 1, wherein ΔL* is measured with a spectrophotometer at 150° C. for 72 hours, at a content of at least 0.15 wt. % of the at least one thiadiazole compound; and wherein ΔL* is measured by the formula ΔL*=L* aged fluid −L* fresh fluid .
12. The transmission fluid composition of claim 1 , wherein the base oil comprises from about 70 wt. % to about 95 wt % of the total weight of the transmission fluid composition.
13. The transmission fluid composition of claim 1 , wherein the sulfur content delivered to the transmission fluid composition by the at least one thiadiazole compound of the Formulas (I)-(II) is from about 50 to about 10,000 ppm.
14. The transmission fluid composition of claim 1 , wherein the sulfur content delivered to the transmission fluid composition by the at least one thiadiazole compound of the Formulas (I)-(II) is from about 300 to about 2,500 ppm.
15. The transmission fluid composition of claim 1 , wherein the sulfur content delivered to the transmission fluid composition by the at least one thiadiazole compound of the Formulas (I)-(II) is from about 400 to about 2,000 ppm.
16. The transmission fluid composition of claim 1 , wherein the total sulfur content of the transmission fluid composition is from about 50 to about 12,000 ppm.
17. An automatic transmission containing the transmission fluid composition of claim 1 .
18. The automatic transmission of claim 17 , wherein the automatic transmission is selected from the group consisting of a continuously variable transmission, step type transmission or double clutch transmission.
19. A method of operating a transmission comprising a step of operating the transmission lubricated with the transmission fluid composition of claim 1 .
20. A vehicle comprising an engine and a transmission, the transmission including the transmission fluid composition of claim 1 .
21. An additive composition for a transmission fluid, the additive composition comprising at least one color stable extreme pressure performance improver selected from one of
(a) a reaction product of thiadiazole of one of the formulae (III) and (IV):
wherein R 1 is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms; and a thiol of the formula R 3 —SH, wherein R 3 is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms, and optionally an additional sulfur source; and
(b) compounds of the Formulas (I)-(II):
wherein n is 1-5; R 1 is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms; and R 2 is a hydrogen or is a substituted or unsubstituted hydrocarbyl group having 1-100 carbon atoms.
22. The additive composition for a transmission fluid of claim 21 , wherein the additive improves extreme pressure characteristics while maintaining color stability of a transmission fluid.