LUBRICATING AND COOLING FLUID FOR AN ELECTRIC MOTOR SYSTEM HAVING AN AUXILIARY FLUID PUMPING SYSTEM

Abstract

A durable lubricating and cooling fluid for an electric motor system including an auxiliary pumping mechanism. The fluid includes a lubricating base oil, a sulfur system, a nitrogen system, and a phosphorous antiwear system. The lubricating and cooling fluid includes selected amounts of sulfur, nitrogen, and phosphorus provided by the system to provide acceptable wear and friction performance, electrical conductivity, and the ability to minimize wear loss of pumping components making the fluid suitable for use in electric motor system.

Claims

1. A method for lubricating a driveline in an electric motor system and simultaneously cooling a motor thereof using an oil pump, wherein the electric motor system includes a sump, copper windings in a stator, and the oil pump, the method comprising: lubricating portions of the driveline in the electric motor system with the lubricating and cooling fluid and simultaneously cooling the electric motor system by contacting at least the copper windings with the lubricating and cooling fluid; wherein the lubricating and cooling fluid includes a base oil of lubricating viscosity including an API Group III base oil, an API Group IV base oil, or mixtures thereof, a sulfur system including (a) a thiadiazole or hydrocarbyl-substituted derivative thereof and (b) a sulfurized ester, wherein a weight ratio of (a) to (b) is about 1.1:1 or greater; a nitrogen system including a first phosphorylated and boronated dispersant obtained from a polyisobutylene having a number average molecular weight of about 1100 to about 5000 and delivering about 300 to about 700 ppm nitrogen to the lubricating and cooling fluid and a second dispersant having a number average molecular weight of about 1000 or less and delivering up to about 150 ppm nitrogen to the lubricating and cooling fluid; a phosphorus antiwear system providing at least about 550 ppm phosphorus to the lubricating and cooling fluid and including three phosphorus antiwear additives of at least (i) a trialkyl phosphate ester having C4 to C8 linear or branched alkyl groups in each of the ester moieties; (ii) an ashless, amine free dialkyl dithiophosphate acid ester; and (iii) an amine salt of a phosphoric acid ester; and wherein at least 50 weight percent of total phosphorus in the lubricating and cooling fluid is provided by component (i), no more than about 10 weight percent of the total phosphorus is provided by component (ii), and no more than about 20 weight percent of the total phosphorus is provided by component (iii).

2. The method of claim 1 wherein the lubricating and cooling fluid, passes wear durability pursuant to the MB Pumptest.

3. The method of claim 1, wherein the method further includes operating an electric motor system, containing a lubricating and cooling fluid, such that a temperature of the lubricating and cooling fluid in a sump of the electric motor system is about 70 C. to about 135 C. and a peak-temperature of the copper windings in a stator of the electric motor system is up to about 230 C.

4. The method of claim 1, wherein the first phosphorylated and boronated dispersant is obtained from a polyisobutylene having a number average molecular weight of about 1500 to about 2500.

5. The method of claim 1, wherein the thiadiazole or hydrocarbyl-substituted derivative thereof of the sulfur system delivers about 1200 to about 2000 ppm sulfur to the lubricating and cooling fluid and/or wherein the sulfurized ester of the sulfur system delivers up to about 300 ppm sulfur to the lubricating and cooling fluid.

6. The method of claim 1, wherein the trialkyl phosphate ester (i) of the phosphorus antiwear system has a structure of Formula II: ##STR00017## wherein R.sub.3, R.sub.4, and R.sub.5 of Formula II are, independently, a C4 to C8 linear or branched alkyl group.

7. The method of claim 1, wherein the trialkyl phosphate ester (i) of the phosphorus antiwear system is tris (2-ethylhexyl) phosphate

8. The method of claim 1, wherein the ashless, amine free dialkyl dithiophosphate acid ester (ii) of the phosphorus antiwear system has a structure of Formula IV, or a salt thereof: ##STR00018## wherein R.sub.6 and R.sub.7 of Formula IV are, independently, a C3 to C8 linear or branched alkyl group, and R.sub.9 is H or CH.sub.3.

9. The method of claim 1, wherein the ashless, amine free dialkyl dithiophosphate acid ester (ii) of the phosphorus antiwear system is 3-[[bis(2-methylpropoxy) phosphinothioyl]thio]-2-methyl-propanoic acid.

10. The method of claim 1, wherein the amine salt of a phosphoric acid ester (iii) of the phosphorus antiwear system includes one or more of a monoalkyl phosphoric acid ester or a dialkyl phosphoric acid esters and wherein the alkyl groups thereof may be linear or branched.

11. The method of claim 10, wherein the amine salt of a phosphoric acid ester (iii) of the phosphorus antiwear system has the structure of Formula V ##STR00019## wherein R.sub.10 and R.sub.11 are independently hydrogen or a linear, branched, or cyclic hydrocarbyl group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p equals 2; R.sub.12, R.sub.13, R.sub.14 and R.sub.15 are, independently, hydrogen or a hydrocarbyl group and at least one of R.sub.12 to R.sub.15 is a hydrocarbyl group.

12. The method of claim 11, wherein R.sub.10 and R.sub.11 are, independently, a C1 to C14 alkyl group.

13. The method of claim 11, wherein at least one of R.sub.12, R.sub.13, R.sub.14 and R.sub.15 is C10 to C20 alkyl group.

14. The method of claim 1, wherein the lubricating and cooling fluid has an electrical conductivity of about 80 nS/M or less, as measured by DIN 51111 modified at 20 Hz at 100 C.

15. The method of claim 1, wherein the lubricating and cooling fluid exhibits a failure load stage rating of 7 or higher pursuant to CEC L-84 at 90 C.

16. The method of claim 1, wherein the lubricating composition has a kV100 less than about 4 cSt.

17. The method of claim 1, wherein about 50 to about 60 weight percent of total phosphorus in the lubricating and cooling fluid is provided by component (i), about 4 to about 10 weight percent of the total phosphorus is provided by component (ii), and about 10 to about 20 weight percent of the total phosphorus is provided by component (iii).

18. The method of claim 1, wherein the thiadiazole or derivative thereof includes one or more compounds having a structure of Formula I: ##STR00020## wherein each R.sub.1 is independently hydrogen or sulfur, each R.sub.2 is independently an alkyl group, n is an integer of 0 or 1 and if R.sub.1 is hydrogen then the integer n of the adjacent R.sub.2 moiety is 0 and if R.sub.1 is sulfur then the n of the adjacent R.sub.2 moiety is 1, and with the proviso that at least one R.sub.1 is sulfur.

19. The method of claim 18, wherein the thiadiazole or derivative thereof has a molecular weight of about 700 or less.

20. The method of claim 1, wherein the second dispersant is present in an amount to deliver up to about 115 ppm nitrogen to the lubricating and cooling fluid.

21. The method of claim 20, wherein the first dispersant is obtained from polyisobutylene having a number average molecular weight of about 2000 to about 2400 and the second dispersant is obtained from polyisobutylene having a number average molecular weight of about 950.

22. The method of claim 1, wherein the lubricating and cooling fluid exhibits a -static friction performance of about 0.101 about 0.115 as measured according to MB10-10N.

23. A durable lubricating and cooling fluid for an electric motor system comprising: a base oil of lubricating viscosity including an API Group III base oil, an API Group IV base oil, or mixtures thereof, a sulfur system including (a) a thiadiazole or hydrocarbyl-substituted derivative thereof and (b) a sulfurized ester, wherein a weight ratio of (a) to (b) is about 1.1:1 or greater; a nitrogen system including a first phosphorylated and boronated dispersant obtained from a polyisobutylene having a number average molecular weight of about 1100 to about 5000 and delivering about 300 to about 700 ppm nitrogen to the lubricating and cooling fluid and a second dispersant obtained from polyisobutylene having a number average molecular weight of about 1000 or less and delivering nitrogen in amounts of about 150 ppm or less nitrogen to the lubricating and cooling fluid; a phosphorus antiwear system providing at least about 550 ppm phosphorus to the lubricating and cooling fluid and including three phosphorus antiwear additives of at least (i) a trialkyl phosphate ester having C4 to C8 linear or branched alkyl groups in each of the ester moieties; (ii) an ashless, amine free dialkyl dithiophosphate acid ester; and (iii) an amine salt of a phosphoric acid ester, wherein at least 50 weight percent of total phosphorus in the lubricating and cooling fluid is provided by component (i), no more than about 10 weight percent of the total phosphorus is provided by component (ii), and no more than about 20 weight percent of the total phosphorus is provided by component (iii); and wherein the lubricating and cooling fluid has an electrical conductivity of about 80 nS/M or less, as measured by DIN 51111 modified at 20 Hz at 100 C.

24. The durable lubricating and cooling fluid of claim 23, wherein the lubricating and cooling fluid passes durability as performed by the MB Pumptest.

25. The durable lubricating and cooling fluid of claim 23, wherein the thiadiazole or hydrocarbyl-substituted derivative thereof of the sulfur system delivers about 1200 to about 2000 ppm sulfur to the lubricating and cooling fluid and/or wherein the sulfurized ester delivers up to about 300 ppm sulfur to the lubricating and cooling fluid.

26. The durable lubricating and cooling fluid of claim 23, wherein the phosphorylated and boronated dispersant obtained is from a polyisobutylene having a number average molecular weight of about 1500 to about 2500.

27. The durable lubricating and cooling fluid of claim 23, wherein the trialkyl phosphate ester (i) of the phosphorus antiwear system has a structure of Formula II: ##STR00021## wherein R.sub.3, R.sub.4, and R.sub.5 of Formula II are, independently, a C4 to C8 linear or branched alkyl group.

28. The durable lubricating and cooling fluid of claim 23, wherein the trialkyl phosphate ester (i) of the phosphorus antiwear system is tris (2-ethylhexyl) phosphate.

29. The durable lubricating and cooling fluid of claim 23, wherein the ashless, amine free dialkyl dithiophosphate acid ester (ii) of the phosphorus antiwear system has a structure of Formula IV, or a salt thereof: ##STR00022## wherein R.sub.6 and R.sub.7 of Formula IV are, independently, a C3 to C8 linear or branched alkyl group, and R.sub.9 is H or CH.sub.3.

30. The durable lubricating and cooling fluid of claim 23, wherein the ashless, amine free dialkyl dithiophosphate acid ester (ii) of the phosphorus antiwear system is 3-[[bis(2-methylpropoxy) phosphinothioyl]thio]-2-methyl-propanoic acid.

31. The durable lubricating and cooling fluid of claim 23, wherein the amine salt of a phosphoric acid ester (iii) of the phosphorus antiwear system includes one or more of a monoalkyl phosphoric acid ester or a dialkyl phosphoric acid esters and wherein the alkyl groups thereof may be linear or branched.

32. The durable lubricating and cooling fluid of claim 31, wherein the amine salt of a phosphoric acid ester (iii) of the phosphorus antiwear system has the structure of Formula V ##STR00023## wherein R.sub.10 and R.sub.11 are independently hydrogen or a linear, branched, or cyclic hydrocarbyl group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p equals 2; R.sub.12, R.sub.13, R.sub.14 and R.sub.15 are independently hydrogen or a hydrocarbyl group and at least one of R.sub.12 to R.sub.15 is a hydrocarbyl group.

33. The durable lubricating and cooling fluid of claim 32, wherein R.sub.10 and R.sub.11 are, independently, a C1 to C14 alkyl group.

34. The durable lubricating and cooling fluid of claim 33, wherein at least one of R.sub.12, R.sub.13, R.sub.14 and R.sub.15 is C10 to C20 alkyl group.

35. The durable lubricating and cooling fluid of claim 23, wherein the lubricating and cooling fluid exhibits a fail load stage rating of 7 or higher pursuant to CEC L-84 at 90 C.

36. The durable lubricating and cooling fluid of claim 23, wherein the lubricating composition has a kV100 less than about 4 cSt.

37. The durable lubricating and cooling fluid of claim 23, wherein about 50 to about 60 weight percent of total phosphorus in the lubricating and cooling fluid is provided by component (i), about 4 to about 10 weight percent of the total phosphorus is provided by component (ii), and about 10 to about 20 weight percent of the total phosphorus is provided by component (iii).

38. The durable lubricating and cooling fluid of claim 23, wherein the thiadiazole or derivative thereof includes one or more compounds having a structure of Formula I: ##STR00024## wherein each R.sub.1 is independently hydrogen or sulfur, each R.sub.2 is independently an alkyl group, n is an integer of 0 or 1 and if R.sub.1 is hydrogen then the integer n of the adjacent R.sub.2 moiety is 0 and if R.sub.1 is sulfur then the n of the adjacent R.sub.2 moiety is 1, and with the proviso that at least one R.sub.1 is sulfur.

39. The durable lubricating and cooling fluid of claim 28, wherein the thiadiazole or derivative thereof has a molecular weight of about 700 or less.

40. The durable lubricating and cooling fluid of claim 23, wherein the second dispersant is present in an amount to deliver up to about 115 ppm nitrogen to the durable lubricating and cooling fluid.

41. The durable lubricating and cooling fluid of claim 40, wherein the first dispersant is obtained from polyisobutylene having a number average molecular weight of about 2000 to about 2400 and the second dispersant is obtained from polyisobutylene having a number average molecular weight of about 950.

Description

DETAILED DESCRIPTION

[0010] According to an exemplary embodiment, a durable lubricating and cooling fluid for an electric motor system configured to lubricant gears and/or clutches of a vehicle powertrain and also cool the electric motor at the same time is described herein. The fluid is also designed to minimize wear on auxiliary pumping mechanisms for the electric motor systems, so that the fluids herein not only achieve performance of a lubricant and effectively cool the electric motors, but also maintain the durability of the pumping mechanisms at the same time.

[0011] In one embodiment, the durable lubricating and cooling fluids herein include a lubricating base oil of an API Group III base oil, an API Group IV base oil, or mixtures thereof and an additive system including at least (i) a two-component sulfur system; (ii) a nitrogen system including a phosphorylated and boronated dispersant(s); and (iii) a three-component phosphorus antiwear system having selected amounts of phosphorus provided from three phosphorus-providing antiwear additives. In any embodiment herein, the durable lubricating and cooling fluid has a kV100 C. of less than about 4 cSt (ASTM D445) (preferably about 3 to about 4 cSt), an electric conductivity of about 80 nS/M or less (measured according to modified DIN 51111 at 20 Hz at 100 C), an FZG failure load stage rating of 7 or higher at 90 C. (CEC L-84), pt-static friction performance of about 0.101 to about 0.115 as measured according to MB10-10N (Reibwerttest im Getriebekomponenten-Prfstand zur Absicherung der Chargenqualitt von Getriebelen mit Additiven), and/or wherein the auxiliary pumping mechanism passes durability testing performed pursuant to the MB Pumptest (or equivalent) available at APL Automobil-Prftechnik Landau testing facility (or other suitable testing facility).

[0012] With fluids for electric motor systems that need to provide not only wear and friction performance but also, in some instances, cooling, low conductivity, and/or maintain durability of pumping mechanisms, there are challenges developing such a robust fluid because elements and components traditionally used in internal combustion engines and transmissions, which contain sulfur, boron, and phosphorus, can negatively impact electrical conductivity. For instance, while sulfur and phosphorus may provide wear protection in some instances, sulfur, phosphorus and boron can increase the conductivity of fluids. These undesired effects are magnified at elevated temperatures. Thus, carefully developed fluids are required for electric motors and gears that operate at elevated temperatures. For example, the fluid sump temperatures of an electrical motor system described herein can be about 70 C. to about 135 C. Further, the temperature of the copper windings in the stator of the electrical motor system described herein can reach up to about 230 C. peak temperature. At these elevated temperatures, additives in the fluid used to achieve good wear and friction performance can be detrimental to maintaining the desired electrical conductivity. It was discovered herein, however, that sulfur, phosphorus, and boron can be provided to a fluid for such electric mobility (e-mobility) applications if such elements are provided by the unique combination of the sulfur system, the nitrogen system, and the phosphorus antiwear system discovered herein. In one approach, for instance, the durable lubricating and cooling fluids herein include (i) the sulfur system with two sulfur additives including (ia) a thiadiazole or hydrocarbyl-substituted derivative thereof, in some embodiments, delivering about 1200 to about 2000 ppm sulfur to the lubricating and cooling fluid and (ib) a sulfurized ester, in some embodiments, delivering up to about 300 ppm sulfur to the lubricating and cooling fluid and, in other embodiments, wherein a weight ratio of (ia) to (ib) is about 1.1:1 or greater; (ii) the nitrogen system preferably includes a first phosphorylated and boronated dispersant obtained from a polyisobutylene having a number average molecular weight of about 1100 g/mol to about 5000 g/mol (in other embodiments about 1500 g/mol to about 2500 g/mol) and delivering about 300 to about 700 ppm nitrogen to the durable lubricating and cooling fluid and a second dispersant obtained from a polyisobutylene having a number average molecular weight of about 1000 g/mol or less, or about 500 to about 1000 g/mol and is present in the lubricating and cooling fluid in an amount sufficient to deliver less than about 150 ppm nitrogen, or less than about 130 ppm nitrogen, less than about 115 ppm nitrogen, or less than 110 ppm nitrogen and in other approaches the second dispersant includes, more than about 10 ppm nitrogen, more than about, 20 ppm nitrogen, more than 30 ppm nitrogen, more than about 50 ppm nitrogen, or more than about 80 ppm nitrogen (or any other ranges of such amounts herein); (iii) a phosphorus antiwear system providing at least about 550 ppm phosphorus to the durable lubricating and cooling fluid (in other embodiments, at least about 600 ppm phosphorus) and including three phosphorus antiwear additives of at least (iiia) a trialkyl phosphate ester having C4 to C8 linear or branched alkyl groups in each of the ester moieties; (iiib) an ashless, amine free dialkyl dithiophosphate acid ester; and (iiic) an amine salt of a phosphoric acid ester, and in at least one embodiment, where at least about 50 weight percent of total lubricant phosphorus in the durable lubricating and cooling fluid is provided by component (iiia), no more than about 10 weight percent of the total lubricant phosphorus is provided by component (iiib), and no more than about 30 weight percent of the total lubricant phosphorus is provided by component (iiic).

[0013] In another exemplary embodiment, the disclosure herein relates to a method of lubricating gears and/or clutches in an electric motor system while simultaneously cooling an electric motor in the electric motor system and when using an auxiliary oil pump for fluid transport. According to one embodiment of this method, the electric motor system is operated with a durable lubricating and cooling fluid, such that a temperature of the durable lubricating and cooling fluid in a sump of the electric motor system is about 70 C. to about 135 C. and a temperature of the copper windings in a stator of the electric motor system is about 150 C. to about 180 C., with peak temperatures up to 230 C.; portions of the driveline in the electric motor system are lubricated with the durable lubricating and cooling fluid and the elector motor system is simultaneously cooled by contacting at least the copper windings with the durable lubricating and cooling fluid, and wherein the lubrication (e.g., fluid transport throughout the system) is provided by an auxiliary oil pump or mechanism. In embodiments of this method, suitable durable lubricating and cooling fluids include a base oil of lubricating viscosity with an API Group III base oil (including gas-to-liquid base oils), or API Group IV base oil, or mixtures thereof; (i) a sulfur system including (ia) a thiadiazole or hydrocarbyl-substituted derivative thereof delivering, in some embodiments, about 1200 to about 2000 ppm sulfur to the lubricating and cooling fluid and (ib) a sulfurized ester delivering, in some embodiments, up to about 300 ppm sulfur to the lubricating and cooling fluid and, in some embodiments, with a weight ratio of (a) to (b) of 1.1:1 or greater; (ii) a nitrogen system including a phosphorylated and boronated dispersant obtained from a polyisobutylene having a number average molecular weight of about 1100 to about 5000 g/mol (in other embodiments, about 1500 to about 2500 g/mol) and delivering about 300 to about 700 ppm nitrogen to the lubricating and cooling fluid and a second dispersant obtained from a polyisobutylene having a number average molecular weight of about 1000 g/mol or less, or about 500 to about 1000 g/mol and is present in the lubricating and cooling fluid in an amount sufficient to deliver less than about 150 ppm nitrogen, or less than about 130 ppm nitrogen, less than about 115 ppm nitrogen, or less than 110 ppm nitrogen (in other approaches the second dispersant includes, more than about 10 ppm nitrogen, more than about 20 ppm nitrogen, more than 30 ppm nitrogen, more than about 50 ppm nitrogen, or more than about 80 ppm nitrogen (or any other ranges of such amounts herein)); and (iii) a phosphorus antiwear system providing at least about 550 ppm phosphorus to the lubricating and cooling fluid (in other embodiments, at least about 600 ppm phosphorus) and including three phosphorus antiwear additives of at least (iiia) a trialkyl phosphate ester having C4 to C8 linear or branched alkyl groups in each of the ester moieties; (iiib) an ashless, amine free dialkyl dithiophosphate acid ester; and (iiic) an amine salt of a phosphoric acid ester, and wherein at least 50 weight percent of total phosphorus in the lubricating and cooling fluid is provided by component (iiia), no more than about 10 weight percent of the total phosphorus is provided by component (iiib), and no more than about 20 weight percent of the total phosphorus is provided by component (iiic).

[0014] In any embodiment of the methods herein, the durable lubricating and cooling fluid has a kV100 of less than about 4 cSt (ASTM D445) (preferably, about 3 to about 4 cSt), an electric conductivity of about 80 nS/M or less (measured according to DIN 51111 (modified at 20 Hz at 100 C), a FZG failure load stage rating of 7 or higher at 90 C. (CEC L-84), pt-static friction performance of between about 0.101 to about 0.115 as measured according to MB10-10N (Reibwerttest im Getriebekomponenten-Prfstand zur Absicherung der Chargenqualitt von Getriebelen mit Additiven), and/or wherein the auxiliary pumping mechanism passes durability testing performed pursuant to the MB Pumptest (or equivalent) available at APL Automobil-Prftechnik Landau testing facility or other suitable testing facility.

Base Oil:

[0015] Base oils suitable for use in formulating the durable lubricating and cooling fluids for use in electric motor vehicles according to the disclosure may be selected from any of suitable synthetic or natural oils or mixtures thereof having a suitable lubricating viscosity. Natural oils may include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as mineral oils such as liquid petroleum oils and solvent treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils derived from coal or shale may also be suitable. Further, oil derived from a gas-to-liquid process is also suitable. The base oil may have a kinematic viscosity at 100 C. of about 2 to about 15 cSt, as measured by ASTM ASTM D445-24.

[0016] The base oil as used herein may be a single base oil or may be a mixture of two or more base oils. The one or more base oil(s) may be selected from any of the base oils in Group III (including gas-to-liquid base oils) or Group IV as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. Such base oil groups are shown in Table 1 as follows:

TABLE-US-00001 TABLE 1 Base oil Saturates Viscosity Category Sulfur (%) (%) Index API Group I >0.03 and/or <90 80 to 120 API Group II 0.03 and 90 80 to 120 API Group III 0.03 and 90 120 API Group IV All polyalphaolefins (PAOs) API Group V All others not included in Groups I, II, III, or IV

[0017] In one variation, the base oil may be selected from an API Group III base oil, or an API Group IV base oil, or a mixture of these base oils. Alternatively, the base oil may be a mixture of two or more of an API Group III base oils, or two or more of an API Group IV base oils.

[0018] API Group III base oils may include oil derived from Fischer-Tropsch synthesized hydrocarbons (gas-to-liquid base oils). Fischer-Tropsch synthesized hydrocarbons are made from synthesis gas containing H.sub.2 and CO using a Fischer-Tropsch catalyst. Such hydrocarbons typically require further processing in order to be useful as the base oil. These types of oils are commonly referred to as gas-to-liquids (GTLs). For example, the hydrocarbons may be hydroisomerized using processes disclosed in U.S. Pat. No. 6,103,099 or 6,180,575; hydrocracked and hydroisomerized using processes disclosed in U.S. Pat. No. 4,943,672 or 6,096,940; dewaxed using processes disclosed in U.S. Pat. No. 5,882,505; or hydroisomerized and dewaxed using processes disclosed in U.S. Pat. Nos. 6,013,171; 6,080,301; or 6,165,949.

[0019] API Group IV base oils, PAOs, are typically derived from monomers having from 4 to 30, or from 4 to 20, or from 6 to 16 carbon atoms. Examples of PAOs that may be used in the present invention include those derived from octene, decene, mixtures thereof, and the like. PAOs may have a kinematic viscosity of from 2 to 15, or from 3 to 12, or from 4 to 8 cSt at 100 C., as measured by ASTM D2270-10. Examples of PAOs include 4 cSt at 100 C. PAOs, 6 cSt at 100 C. PAOs, and mixtures thereof.

[0020] The base oil(s) are combined with an additive composition as disclosed in embodiments herein to provide a lubricating and cooling fluid for use in an electric motor system having an electric motor, gears, and/or clutches. Accordingly, the base oil may be present in the lubricating and cooling fluid in an amount greater than about 80 wt % based on the total weight of the lubricating and cooling fluid. In some embodiments, the base oil may be present in the lubricating and cooling fluid in an amount greater than about 85 wt % based on the total weight of the lubricating and cooling fluid.

Additive Composition:

[0021] The durable lubricating and cooling fluids herein include an additive composition that includes at least a sulfur system, a nitrogen system, and a phosphorus antiwear system. Each are described below.

The Sulfur System:

[0022] The durable lubricating and cooling fluids herein include a two-component sulfur system including at least (1) one or more thiadiazole compounds or hydrocarbyl-substituted derivatives thereof and (2) a sulfurized ester. In one embodiment, the sulfur system has a weight ratio of (a) to (b) of at least about 1.1 or greater (e.g., about 1.1:1 or greater).

[0023] The first sulfur component of the sulfur system is one or more thiadiazole compounds or hydrocarbyl-substituted derivatives thereof. Examples of the thiadiazole compound that may be used include 2,5-dimercapto-1,3,4-thiadiazole, 2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazole, 2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazole, 2,5-bis(hydrocarbylthio)-1,3,4-thiadiazole, or 2,5-bis(hydrocarbyldithio)-1,3,4-thiadiazoles. The 1,3,4-thiadiazoles are generally synthesized from hydrazine and carbon disulfide by known procedures. See, for example, U.S. Pat. Nos. 2,765,289; 2,749,311; 2,760,933; 2,850,453; 2,910,439; 3,663,561; 3,862,798; and 3,840,549 with relevant portions thereof incorporated herein by reference.

[0024] In approaches, the at least one or more thiadiazole compounds or hydrocarbyl-substituted derivatives thereof includes one or more compounds having a structure of Formula I:

##STR00009##

wherein each R.sub.1 is independently hydrogen or sulfur, each R.sub.2 is independently an alkyl group, n is an integer of 0 or 1 and if R.sub.1 is hydrogen then the integer n of the adjacent R.sub.2 moiety is 0 and if R.sub.1 is sulfur then the n of the adjacent R.sub.2 moiety is 1, and with the proviso that at least one R.sub.1 is sulfur. In other approaches, the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof is a blend of compounds of Formula Ia and Formula Ib shown below:

##STR00010##

wherein within Formula Ia each integer n is 1, each R.sub.1 is sulfur, and each R.sub.2 is a C5 to C15 alkyl group, preferably a C8 to C12 alkyl group; and

##STR00011##

wherein within Formula Ib one integer n is 1 with an associated R.sub.2 group being a C5 to C15 alkyl group (preferably a C8 to C12 alkyl group) and the other integer n is 0 and with both R.sub.1 groups being sulfur. In some embodiments, the first sulfurized additive includes a blend of Formula Ia and Ib with Formula Ia being a majority of the blend and in other approaches, the blend of Ia and Ib is about 75 to about 90 weight percent of Ia and about 10 to about 25 weight percent of Ib (or other ranges therewithin). In another approach, the first sulfurized additive is a 2,5-dimercapto 1,3,4 thiadiazole including a blend of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole (such as about 75 to about 90%) and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole (such as about 10 to about 25%).

[0025] The at least one or more thiadiazole compounds or hydrocarbyl-substituted derivative thereof are present in the lubricating and cooling fluid, in some embodiments, in an amount to deliver about 1200 to about 2000 ppm sulfur, about 1300 to about 1800 ppm sulfur, or about 1400 to about 1600 ppm sulfur (or other ranges therewithin) to the fluid. In one embodiment, the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof includes 2,5-dimercapto-1,3,4-thiadiazole and is present in the lubricating and cooling fluid in an amount to deliver about 1200 to about 2000 ppm sulfur, about 1300 to about 1800 ppm sulfur, or about 1400 to about 1600 ppm sulfur (or other ranges therewithin).

[0026] The durable lubricating and cooling fluids herein also includes a second sulfur component in the form of a sulfurized ester. Examples of sulfurized esters include those produced by sulfurizing animal or vegetable fats and oils such as beef tallow lard, fish oil, rapeseed oil, and soybean oil; unsaturated fatty acid esters produced by reacting unsaturated fatty acids such as oleic acid, linoleic acid, and fatty acids extracted from the foregoing animal or vegetable fats and oils with various alcohols; or mixtures thereof, by any suitable method. In one embodiment, the sulfurized component is sperm oil or synthetic sperm oil and is comprised of sulfurized transesterified triglycerides.

[0027] The sulfurized ester, in some embodiments, may be present in the lubricating and cooling fluid in an amount to deliver up to about 300 ppm sulfur, about 200 to about 300 ppm sulfur, or about 225 to about 280 ppm sulfur (or other ranges therewithin). In one embodiment, the sulfurized ester is sulfurized synthetic sperm oil comprised of sulfurized transesterified triglycerides and may be present in the lubricating and cooling fluid an amount to deliver about 200 to about 300 ppm sulfur or about 225 to about 280 ppm sulfur (or other ranges therewithin).

[0028] In other embodiments, the sulfur system herein provides a total amount of sulfur of about 1400 to about 2300 ppm sulfur or about 1400 to about 2000 ppm sulfur or about 1700 to about 2000 ppm sulfur (or other ranges therewithin). In one embodiment, the first sulfur component is 2,5-dimercapto-1,3,4-thiadiazole and/or hydrocarbyl-substituted derivatives thereof and the second sulfur component is sulfurized synthetic sperm oil comprised of sulfurized transesterified triglycerides. In this embodiment, the first sulfur component is present in the durable lubricating and cooling fluid in an amount to deliver about 1400 to about 1600 ppm sulfur and the second sulfur component is present in the durable lubricating and cooling fluid in an amount to deliver about 225 to about 280 ppm sulfur. In this embodiment, the first and second sulfur components may be present in the durable lubricating and cooling fluid in an amount to deliver about 1600 to about 2000 ppm total sulfur.

The Nitrogen System:

[0029] The durable lubricating and cooling fluid described herein also contain a nitrogen system including at least one dispersant, such as oil-soluble ashless dispersants selected from the group consisting of succinimide dispersants, succinic ester dispersants, succinic ester-amide dispersants, Mannich base dispersants, polymeric polyamine dispersants, phosphorylated forms thereof, and borated forms thereof. The at least one dispersant may be capped with acidic molecules capable of reacting with secondary amino groups. Preferably, the nitrogen system herein includes a dispersant having a selected molecular weight and provides nitrogen, phosphorous, and boron to the lubricants, and more preferably, a phosphorylated and boronated dispersant obtained from a polyisobutylene having a number average molecular weight of about 1100 g/mol to about 5000 g/mol (in other embodiments, about 1500 to about 2500 g/mol, and preferably about 2,000 to about 2,500 g/mol) and delivering about 300 to about 700 ppm nitrogen to the durable lubricating and cooling fluid. The lubricating and cooling fluid described herein also includes a second dispersant obtained from a polyisobutylene having a number average molecular weight of about 1000 g/mol or less, or about 500 to about 1000 g/mol and is present in the lubricating and cooling fluid in an amount sufficient to deliver less than about 150 ppm nitrogen.

[0030] Suitable dispersants may be obtained from hydrocarbyl-substituted dicarboxylic acid or anhydrides reacted with polyalkylene polyamines, which are used to make succinimide dispersants. Succinimide dispersants and their preparation are disclosed in U.S. Pat. Nos. 7,897,696 and 4,234,435, which are incorporated herein by reference. The hydrocarbyl moiety of the hydrocarbyl-dicarboxylic acid or anhydride of may be derived from butene polymers, for example polymers of isobutylene. Suitable polyisobutenes for use herein include those formed from conventional polyisobutylene or highly reactive polyisobutylene having at least 60%, such as 70% to 90% and above, terminal vinylidene content. Suitable polyisobutenes may include those prepared using BF.sub.3 catalysts.

[0031] The polyisobutylene moiety in a dispersant preferably has a narrow molecular weight distribution (MWD), also referred to as polydispersity, as determined by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). Polymers having a Mw/Mn of less than about 2.2, preferably less than about 2.0, are most desirable. Suitable polyisobutylene substituents have a polydispersity of from about 1.5 to about 2.1, or from about 1.6 to about 1.8.

[0032] The dicarboxylic acid or anhydride of may be selected from carboxylic reactants such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethylmaleic anhydride, dimethylmaleic anhydride, ethylmaleic acid, dimethylmaleic acid, hexylmaleic acid, and the like, including the corresponding acid halides and C.sub.1-C.sub.4 aliphatic esters. A mole ratio of dicarboxylic acid or anhydride to hydrocarbyl moiety in a reaction mixture used to make the hydrocarbyl-dicarboxylic acid or anhydride may vary widely. Accordingly, the mole ratio may vary from 5:1 to 1:5, for example from 3:1 to 1:3. A particularly suitable molar ratio of acid or anhydride to hydrocarbyl moiety is from 1:1 to less than 1.6:1. Another useful molar ratio of dicarboxylic acid or anhydride to hydrocarbyl moiety is 1.3:1 to 1.7:1, or 1.3:1 to 1.6:1, or 1.3:1 to 1.5:1.

[0033] Any of numerous polyalkylene polyamines can be used as in preparing the dispersant additive. Non-limiting exemplary polyamines may include aminoguanidine bicarbonate (AGBC), diethylene triamine (DETA), triethylene tetramine (TETA), tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA) and heavy polyamines. A heavy polyamine may comprise a mixture of polyalkylenepolyamines having small amounts of polyamine oligomers such as TEPA and PEHA, but primarily oligomers having seven or more nitrogen atoms, two or more primary amines per molecule, and more extensive branching than conventional polyamine mixtures. Typically, these heavy polyamines have an average of 6.5 nitrogen atoms per molecule. Additional non-limiting polyamines which may be used to prepare the hydrocarbyl-substituted succinimide dispersant are disclosed in U.S. Pat. No. 6,548,458, the disclosure of which is incorporated herein by reference in its entirety. The molar ratio of hydrocarbyl-dicarboxylic acid or anhydrides to polyalkylene polyamines may be from about 1:1 to about 3.0:1.

[0034] In one embodiment, the dispersants in the present disclosure described herein may be the reaction product of a polyisobutenyl succinic anhydride (PIBSA), and a polyamine, for example heavy polyamines. The dispersants herein may have a molar ratio of (A) polyisobutenyl-substituted succinic anhydride to (B) polyamine in the range of 4:3 to 1:10.

[0035] The Mannich base dispersants may be a reaction product of an alkyl phenol, typically having a long chain alkyl substituent on the ring, with one or more aliphatic aldehydes containing from about 1 to about 7 carbon atoms (especially formaldehyde and derivatives thereof), and polyamines (especially polyalkylene polyamines). For example, a Mannich base ashless dispersants may be formed by condensing about one molar proportion of long chain hydrocarbon-substituted phenol with from about 1 to about 2.5 moles of formaldehyde and from about 0.5 to about 2 moles of polyalkylene polyamine.

[0036] In embodiments, the nitrogen systems herein preferably include two dispersants. In one embodiment, at least one of the dispersants is borated and/or phosphorylated. Each of the dispersants may generally be the reaction products of i) at least one phosphorus compound and/or a boron compound and ii) at least one ashless dispersant.

[0037] Suitable boron compounds useful in forming the dispersants herein include any boron compound or mixtures of boron compounds capable of introducing boron-containing species into the ashless dispersant. Any boron compound, organic or inorganic, capable of undergoing such reaction can be used. Accordingly, use can be made of boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF.sub.4 boron acids such as boronic acid (e.g. alkyl-B(OH).sub.2 or aryl-B(OH).sub.2), boric acid, (i.e., H.sub.3BO.sub.3), tetraboric acid (i.e., H.sub.2B.sub.5O.sub.7), metaboric acid (i.e., HBO.sub.2), ammonium salts of such boron acids, and esters of such boron acids. The use of complexes of a boron trihalide with ethers, organic acids, inorganic acids, or hydrocarbons is a convenient means of introducing the boron reactant into the reaction mixture. Such complexes are known and are exemplified by boron trifluoride-diethyl ether, boron trifluoride-phenol, boron trifluoride-phosphoric acid, boron trichloride-chloroacetic acid, boron tribromide-dioxane, and boron trifluoride-methyl ethyl ether.

[0038] Suitable phosphorus compounds for forming the dispersants herein include phosphorus compounds or mixtures of phosphorus compounds capable of introducing a phosphorus-containing species into the ashless dispersant. Any phosphorus compound, organic or inorganic, capable of undergoing such reaction can thus be used. Accordingly, use can be made of such inorganic phosphorus compounds as the inorganic phosphorus acids, and the inorganic phosphorus oxides, including their hydrates. Typical organic phosphorus compounds include full and partial esters of phosphorus acids, such as mono-, di-, and tri esters of phosphoric acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid and tetrathiophosphoric acid; mono-, di-, and tri esters of phosphorous acid, thiophosphorous acid, dithiophosphorous acid and trithiophosphorous acid; trihydrocarbyl phosphine oxide; trihydrocarbyl phosphine sulfide; mono- and dihydrocarbyl phosphonates, (RPO(OR)(OR) where R and R are hydrocarbyl and R is a hydrogen atom or a hydrocarbyl group), and their mono-, di- and trithio analogs; mono- and dihydrocarbyl phosphonites, (RP(OR)(OR) where R and R are hydrocarbyl and R is a hydrogen atom or a hydrocarbyl group) and their mono- and dithio analogs; and the like. Thus, use can be made of such compounds as, for example, phosphorous acid (H.sub.3PO.sub.3, sometimes depicted as H.sub.2(HPO.sub.3), and sometimes called ortho-phosphorous acid or phosphonic acid), phosphoric acid (H.sub.3PO.sub.4, sometimes called orthophosphoric acid), hypophosphoric acid (H.sub.4P.sub.2O.sub.6), metaphosphoric acid (HPO.sub.3), pyrophosphoric acid (H.sub.4P.sub.2O.sub.7), hypophosphorous acid (H.sub.3PO.sub.2, sometimes called phosphinic acid), pyrophosphorous acid (H.sub.4P.sub.2O.sub.5, sometimes called pyrophosphonic acid), phosphinous acid (H.sub.3PO), tripolyphosphoric acid (H.sub.5P.sub.3O.sub.10), tetrapolyphosphoric acid (H.sub.5P.sub.4O.sub.13), trimetaphosphoric acid (H.sub.3P.sub.3O.sub.9), phosphorus trioxide, phosphorus tetraoxide, phosphorus pentoxide, and the like. Partial or total sulfur analogs such as phosphorotetrathioic acid (H.sub.3PS.sub.4) acid, phosphoromonothioic acid (H.sub.3PO.sub.3S), phosphorodithioic acid (H.sub.3PO.sub.2S.sub.2), phosphorotrithioic acid (H.sub.3POS.sub.3), phosphorus sesquisulfide, phosphorus heptasulfide, and phosphorus pentasulfide (P.sub.2S.sub.5, sometimes referred to as P.sub.4S.sub.10) can also be used in forming dispersants for this disclosure. Also usable, are the inorganic phosphorus halide compounds such as PCl.sub.3, PBr.sub.3, POCl.sub.3, PSCl.sub.3, etc.

[0039] Likewise, use can be made of such organic phosphorus compounds as mono-, di-, and triesters of phosphoric acid (e.g., trihydrocarbyl phosphates, dihydrocarbyl monoacid phosphates, monohydrocarbyl diacid phosphates, and mixtures thereof), mono-, di-, and triesters of phosphorous acid (e.g., trihydrocarbyl phosphites, dihydrocarbyl hydrogen phosphites, hydrocarbyl diacid phosphites, and mixtures thereof), esters of phosphonic acids (both primary, RP(O)(OR).sub.2, and secondary. R.sub.2P(O)(OR)), esters of phosphinic acids, phosphonyl halides (e.g., RP(O)Cl.sub.2 and R.sub.2P(O)Cl), halophosphites (e.g., (RO)PCl.sub.2 and (RO).sub.2PCl), halophosphates (e.g., ROP(O)Cl.sub.2 and (RO).sub.2P(O)Cl), tertiary pyrophosphate esters (e.g., (RO).sub.2P(O)OP(O)(OR).sub.2), and the total or partial sulfur analogs of any of the foregoing organic phosphorus compounds, and the like wherein each hydrocarbyl group contains up to about 100 carbon atoms, preferably up to about 50 carbon atoms, more preferably up to about 24 carbon atoms, and most preferably up to about 12 carbon atoms. Also usable are the halophosphine halides (e.g., hydrocarbyl phosphorus tetrahalides, dihydrocarbyl phosphorus trihalides, and trihydrocarbyl phosphorus dihalides), and the halophosphines (monohalophosphines and dihalophosphines).

[0040] As discussed above, the nitrogen system of the durable lubricating and cooling fluids described herein includes at least a first dispersant. In one embodiment, the first dispersant has a polyisobutenyl moiety having a number average molecular weight in the range from about 1100 g/mol to about 5000 g/mol (in other embodiments, about 1500 g/mol to about 2500 g/mol) and is present in the lubricating and cooling fluid in an amount sufficient to deliver greater than about 300 ppm nitrogen, greater than about 400 ppm nitrogen, or about 300 to about 700 ppm nitrogen, about 300 to about 600 ppm nitrogen, about 400 to about 550 ppm nitrogen, or up to about 700 ppm nitrogen, up to about 600 ppm, or up to about 500 ppm nitrogen (or other ranges therewithin). In another embodiment, a second dispersant is present. The second dispersant has a polyisobutenyl moiety having a number average molecular weight of about 1000 g/mol or less (in other embodiments, about 500 g/mol to about 1000 g/mol) and is present in the lubricating and cooling fluid in an amount sufficient to deliver less than about 150 ppm nitrogen, less than about 130 ppm nitrogen, or less than 115 ppm, or more than 50 ppm nitrogen or more than about 80 ppm nitrogen (or other ranges therewithin).

[0041] The first dispersant is preferably borated and/or phosphorylated. Accordingly, in one embodiment, the dispersant has a boron content from about 0.25 to about 0.5 wt %, a phosphorus content from about 0.5 to about 1 wt % phosphorus, and a nitrogen content from about 1.5 to about 2 wt % nitrogen. In another embodiment, the dispersant has a boron content of from about 0.3 to about 0.4 wt %, a phosphorus content of from about 0.65 to about 0.8 wt % phosphorus, and a nitrogen content of rom about 1.7 to about 1.8 wt % nitrogen. In some cases, the dispersant is borated and phosphorylated and has a boron plus phosphorus to nitrogen ((B+P)/N) weight ratio of from 0:5 to about 0.9:1, or from about 0.6:1 to about 0.85:1, or from about 0.6:1 to about 0.8:1.

[0042] In one embodiment, the dispersant of the first dispersant is borated and phosphorylated and is present in the lubricating and cooling fluid an amount sufficient to deliver less than about 150 ppm boron (or less than 125 ppm boron), less than about 300 ppm phosphorus (or less than 250 ppm phosphorus), or less than about 700 ppm nitrogen (or less than 600 ppm nitrogen, or less than 500 ppm nitrogen). In yet another embodiment, first dispersant is borated and phosphorylated and is present in the lubricating and cooling fluid in an amount sufficient to deliver about 80 to about 150 ppm boron, about 200 to about 250 ppm phosphorus, and about 450 ppm to about 700 ppm of nitrogen or any other range of such elements between the amounts noted herein. While the nitrogen system of the fluids herein preferably includes a first dispersant that is a phosphorylated and boronated dispersant obtained from a polyisobutylene having a number average molecular weight of about 1500 g/mol to about 2500 g/mol and delivering about 300 to about 700 ppm nitrogen to the lubricating and cooling fluid, other dispersants may be provided.

[0043] In another embodiment, a second dispersant is present in the lubricating and cooling fluid. The second dispersant includes a polyisobutenyl moiety having a number average molecular weight of about 1000 g/mol or less, or about 500 g/mol to about 1000 g/mol, and is present in the lubricating and cooling fluid an amount sufficient to deliver less than about 150 ppm nitrogen, or less than about 130 ppm nitrogen, less than about 115 ppm nitrogen, or less than 110 ppm nitrogen. In other approaches, the second dispersant includes, more than about 10 ppm nitrogen, more than about 20 ppm nitrogen, more than 30 ppm nitrogen, more than about 50 ppm nitrogen, or more than about 80 ppm nitrogen (or any other ranges of such amounts herein). In embodiments herein, the second dispersant is preferably not borated and/or phosphorylated and does not provide such elements to the fluid. For example, the fluid may additionally contain a second dispersant obtained from a polyisobutylene having a number average molecular weight of about 700 g/mol to about 1000 g/mol (in other embodiments about 900 to 1000 g/mol) and delivering about 90 to about 120 ppm nitrogen to the durable lubricating and cooling fluid.

[0044] In yet other approaches or embodiments, the nitrogen system of the fluids herein is balanced to provide high levels of boron and phosphorus relative to the total molecular weight of the combined polyisobutenyl moiety within the nitrogen system. Good conductivity was achieved when at least one of the first dispersant and the second dispersant is borated and phosphorylated such that a total amount of boron and phosphorus in the dispersant system relative to the nitrogen in the dispersant system is from about 0.7 to about 0.9.

The Phosphorus Antiwear System:

[0045] The durable lubricating and cooling fluids herein also include a unique phosphorus antiwear system providing at least about 550 ppm phosphorus to the lubricating and cooling fluid (in other embodiments, at least about 600 ppm phosphorus) and including three phosphorus antiwear additives. In approaches, the phosphorus antiwear systems include at least (iiia) a trialkyl phosphate ester having C4 to C8 linear or branched alkyl groups in each of the ester moieties; (iiib) an ashless, amine free dialkyl dithiophosphate acid ester; and (iiic) an amine salt of a phosphoric acid ester. In aspects of this antiwear system, at least 50 weight percent of total phosphorus in the lubricating and cooling fluid is provided by antiwear component (iiia), no more than about 10 weight percent of the total phosphorus is provided by antiwear component (iiib), and no more than about 20 weight percent of the total phosphorus is provided by antiwear component (iiic).

[0046] First Phosphorous Antiwear Additive: In embodiments, the first phosphorus antiwear compound (iiia) of the phosphorus antiwear system is an ashless (e.g., metal-free) phosphorus-containing compound in the form of a trialkyl phosphate ester. In some approaches or embodiments, the first phosphorus compound provides at least about 50 weight percent of the total phosphorus to lubricant and in other approaches, about 50 to about 60 weight percent of the total phosphorus in the lubricant. In embodiments, the first phosphorus compound provides about 450 ppm to about 550 ppm of phosphorus to the lubricant, in other approaches, about 480 ppm to about 520 ppm of phosphorus, in further approaches, about 480 ppm to about 500 ppm of phosphorus to the lubricant. In alternative approaches, the lubricating compositions herein include about 0.4 weight percent to about 1.2 weight percent of the first phosphorus compound, in other approaches, about 0.6 weight percent to about 1.1 weight percent, in further approaches, about 0.6 to about 0.8 weight percent.

[0047] In other embodiments, the first phosphorus antiwear compound of the phosphorus antiwear system has a structure of Formula II:

##STR00012##

wherein R.sub.3, R.sub.4, and R.sub.5 of Formula II are, independently, a C4 to C8 linear or branched alkyl group. The first phosphorus antiwear compound may have about 5 to about 10 weight percent phosphorus. In one preferred approach, the first phosphorus antiwear compound is tris (2-ethylhexyl) phosphate.

[0048] Second Phosphorous Antiwear Additive: In approaches or embodiments, the second phosphorus antiwear compound (iiib) of the phosphorus antiwear systems herein is an acidic thiophosphate or a thiophosphate ester, such as an ashless, amine free dialkyl dithiophosphate acid ester or sulfur-containing phosphoric acid ester. In other approaches or embodiments, the second phosphorus antiwear compound provides no more than about 10 weight percent of the total phosphorus in the lubricant, or in other embodiments, about 4 to about 10 weight percent of the total phosphorus to the lubricant. In some approaches, the second phosphorus compound provides about 30 ppm to about 90 ppm of phosphorus to the lubricating composition, in other approaches, about 40 ppm to about 80 ppm of phosphorus, in further approaches, about 50 ppm to about 70 ppm, or in yet other approaches, about 50 ppm to about 60 ppm of phosphorus. In alternative approaches, the lubricating compositions herein include about 0.02 weight percent to about 0.1 weight percent of the second phosphorus antiwear compound, in other approaches, about 0.04 weight percent to about 0.08 weight percent, and in further approaches, about 0.05 to about 0.07 weight percent.

[0049] In approaches or embodiments, suitable acidic thiophosphates, thiophosphate esters, or sulfur-containing phosphoric acid esters of the second phosphorus compound may have one or more sulfur to phosphorus bonds. In an embodiment, the sulfur-containing phosphorus acid ester may be an acidic thiophosphate, a thiophosphate ester, a thiophosphorus acid or salt thereof. The thiophosphorus acid esters may be dithiophosphorus acid esters. In some approaches, the acidic thiophosphate or thiophosphate ester may have a structure of Formula III or a salt thereof

##STR00013##

wherein R.sub.6 and R.sub.7 of Formula III are each, independently, a linear or branched C1 to C10 hydrocarbyl group and R.sub.8 of Formula III is a C1 to C10 linear or branched carboxylic group or a C1 to C10 linear or branched alkyl alkanoate group. Preferably, R.sub.6 and R.sub.7 are each a C3 to C8 linear or branched alkyl group and R.sub.8 is derived from 2-methyl proponoic acid such that the second phosphorus product (or a salt thereof) has the structure of Formula IV below:

##STR00014##

wherein R.sub.6 and R.sub.7 of Formula IV are, independently, a C3 to C8 linear or branched alkyl group (preferably, a branched C4 group), and R.sub.9 is H or CH.sub.3. In some approaches or embodiments, the second phosphorus product is preferably 3-[[bis(2-methylpropoxy) phosphinothioyl]thio]-2-methyl-propanoic acid.

[0050] Third Phosphorous Antiwear Additive: In approaches or embodiments, the third phosphorus antiwear compound (iiic) of the phosphorus antiwear systems herein is an amine salt of a phosphoric acid ester. In other approaches or embodiments, the third phosphorus antiwear compound provides no more than about 20 weight percent of the total phosphorus to the lubricant, or in other embodiments, about 10 to about 20 weight percent of the total phosphorus. In some approaches, the third phosphorus compound provides about 90 ppm to about 180 ppm of phosphorus to the lubricating composition, in other approaches, about 120 ppm to about 160 ppm of phosphorus, in further approaches, about 130 ppm to about 150 ppm of phosphorus. In alternative approaches, the lubricating compositions herein include about 0.1 weight percent to about 1 weight percent of the third phosphorus antiwear compound, in other approaches, about 0.2 weight percent to about 0.8 weight percent, in further approaches, about 0.2 to about 0.5 weight percent.

[0051] In embodiments, suitable amine salts of a phosphoric acid ester may include one or more monoalkyl phosphoric acid esters, dialkyl phosphoric acid esters, and/or mixtures thereof wherein the alkyl groups thereof may be linear, branched, or cyclic. In approaches or embodiments, the amine salt of a phosphoric acid ester may be represented by Formula V

##STR00015##

wherein R.sub.10 and R.sub.11 may be independently hydrogen or a linear, branched, or cyclic hydrocarbyl group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p equals 2 (the skilled person will understand that if m is 0 (zero) and p is 2, then the phosphate monoester is a diion); R.sub.12, R.sub.13, R.sub.14 and R.sub.15 may be independently hydrogen or a hydrocarbyl group and at least one of R.sub.12 to R.sub.15 is a hydrocarbyl group. Examples of a suitable alkyl or hydrocarbyl group for R.sub.10 and/or R.sub.11 include straight-chain or branched alkyl groups such as, but not limited to, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and/or decyl groups. In yet further exemplary approaches, R.sub.10 and R.sub.11 may be a cyclic hydrocarbyl group and examples include cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, dimethyl cyclopentyl, methylcyclopentyl, dimethyl cyclopentyl, methylethylcyclopentyl, diethylcyclo-pentyl, methylcyclohexyl, dimethyl-cyclohexyl, methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl, dimethylcycloheptyl, methylethyl-cycloheptyl, and/or diethylcycloheptyl. In some approaches or embodiments, suitable amine salts of a phosphoric acid ester is a mixture of monoalkyl and dialkyl phosphoric acid esters. The monoalkyl and dialkyl groups may be linear, branched, or cyclic as noted above.

[0052] The amine salt of a phosphoric acid ester may be derived from a primary, secondary, or tertiary amine, or mixtures thereof. Exemplary amines suitable for the salt may be aliphatic, cyclic, aromatic or non-aromatic, but commonly is an aliphatic amine. Examples of suitable primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, bis-(2-ethylhexyl)amine, octylamine, and dodecyl-amine, and fatty amines such as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine or oleyamine. Examples of suitable secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine, N-methyl-1-amino-cyclo-hexane, and/or ethylamylamine. The secondary amines may also be cyclic amines such as piperidine, piperazine and morpholine. Examples of suitable tertiary amines may include tri-n-butylamine, tri-n-octylamine, tri-decylamine, tri-laurylamine, tri-hexadecylamine, and/or dimethyl-oleylamine.

[0053] In some approaches, the amine of Formula V above may have at least one of the R.sub.12, R.sub.13, R.sub.14 or R.sub.15 groups being a C10 to C20 alkyl group, and in other approaches or embodiments, at least two of the R.sub.12, R.sub.13, R.sub.14 or R.sub.15 groups are independently a C10 to C20 alkyl group. In some embodiments, at least two of the R.sub.12, R.sub.13, R.sub.14 or R.sub.15 groups are independently a C12 to C14 alkyl group.

[0054] The amine salt of a phosphoric acid ester may be prepared by reacting suitable phosphorus compounds with an amine to form the amine salt of a phosphoric acid ester. In one embodiment, the amine salt of a phosphoric acid ester may be of Formula V wherein R.sub.10 and R.sub.1 may be independently C6 or hydrogen; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p equals 2; R.sub.12, R.sub.13, R.sub.14 or R.sub.15 groups may be independently hydrogen or a hydrocarbyl group of C12-C14 and at least one of R.sub.12 to R.sub.15 is a hydrocarbyl group of C12-C14.

Other Additives

[0055] The durable lubricating and cooling fluid described herein may also include other additives of the type used in electric vehicle powertrain fluid compositions in addition to the components and relationships described above. Such additives include, but are not limited to, antioxidant(s), viscosity modifier(s), other phosphorus-containing components, detergent(s), corrosion inhibitor(s), antirust additives, antifoam agent(s), demulsifier(s), pour point depressant(s), seal swell agent(s), and additional dispersant(s), additional friction modifier(s), and additional sulfur-containing component(s).

[0056] ANTIOXIDANTS: In some embodiments, the durable lubricating and cooling fluid contains one more antioxidants. Suitable antioxidants include phenolic antioxidants, aromatic amine antioxidants, sulfur containing antioxidants, and organic phosphites, among others.

[0057] Examples of phenolic antioxidants include 2,6-di-tert-butylphenol, liquid mixtures of tertiary butylated phenols, 2,6-di-tert-butyl-4-methylphenol, 4,4-methylenebis(2,6-di-tert-butylphenol), 2,2-methylenebis(4-methyl-6-ter-t-butylphenol), and mixed methylene-bridged polyalkyl phenols, and 4,4-thiobis(2-methyl-6-tert-butylphenol), N,N-di-sec-butyl-phenylenediamine,

[0058] 4-iisopropylaminodiphenylamine, phenyl-alpha-naphthyl amine, phenyl-alpha-naphthyl amine, and ring-alkylated diphenylamines. Examples include the sterically hindered tertiary butylated phenols, bisphenols and cinnamic acid derivatives and combinations thereof.

[0059] Aromatic amine antioxidants include, but are not limited to diarylamines having the formula:

##STR00016##

wherein R and R of the above formula each independently represents a substituted or unsubstituted aryl group having from 6 to 30 carbon atoms. Illustrative of substituents for the aryl group include aliphatic hydrocarbon groups such as alkyl having from 1 to 30 carbon atoms, hydroxy groups, halogen radicals, carboxylic acid or ester groups, or nitro groups.

[0060] The aryl group is preferably substituted or unsubstituted phenyl or naphthyl, particularly wherein one or both of the aryl groups are substituted with at least one alkyl having from 4 to 30 carbon atoms, preferably from 4 to 18 carbon atoms, most preferably from 4 to 9 carbon atoms. It is preferred that one or both aryl groups be substituted, e.g. mono-alkylated diphenylamine, di-alkylated diphenylamine, or mixtures of mono- and di-alkylated diphenylamines.

[0061] Examples of diarylamines that may be used include, but are not limited to: diphenylamine; various alkylated diphenylamines, 3-hydroxydiphenylamine, N-phenyl-1,2-phenylenediamine, N-phenyl-1,4-phenylenediamine, monobutyldiphenyl-amine, dibutyldiphenylamine, monooctyldiphenylamine, dioctyldiphenylamine, monononyl diphenylamine, dinonyldiphenylamine, monotetradecyldiphenylamine, ditetradecyl diphenylamine, phenyl-alpha-naphthylamine, monooctyl phenyl-alpha-naphthylamine, phenyl-beta-naphthylamine, monoheptyldiphenylamine, diheptyl-diphenylamine, p-oriented styrenated diphenylamine, mixed butyloctyldi-phenylamine, and mixed octylstyryldiphenylamine.

[0062] The sulfur containing antioxidants include, but are not limited to, sulfurized olefins that are characterized by the type of olefin used in their production and the final sulfur content of the antioxidant. High molecular weight olefins, i.e. those olefins having an average molecular weight of 168 to 351 g/mole, are preferred. Examples of olefins that may be used include alpha-olefins, isomerized alpha-olefins, branched olefins, cyclic olefins, and combinations of these.

[0063] Alpha-olefins include, but are not limited to, any C4 to C25 alpha-olefins. Alpha-olefins may be isomerized before the sulfurization reaction or during the sulfurization reaction. Structural and/or conformational isomers of the alpha olefin that contain internal double bonds and/or branching may also be used. For example, isobutylene is a branched olefin counterpart of the alpha-olefin 1-butene.

[0064] Sulfur sources that may be used in the sulfurization reaction of olefins include: elemental sulfur, sulfur monochloride, sulfur dichloride, sodium sulfide, sodium polysulfide, and mixtures of these added together or at different stages of the sulfurization process.

[0065] Unsaturated oils, because of their unsaturation, may also be sulfurized and used as an antioxidant. Examples of oils or fats that may be used include corn oil, canola oil, cottonseed oil, grapeseed oil, olive oil, palm oil, peanut oil, coconut oil, rapeseed oil, safflower seed oil, sesame seed oil, soybean oil, sunflower seed oil, tallow, and combinations of these.

[0066] The total amount of antioxidant in the lubricating and cooling fluid described herein may be present in an amount to deliver up to about 200 ppm nitrogen, or up to about 100 ppm nitrogen, or up to about 150 ppm nitrogen, or about 100 to about 150 ppm nitrogen.

[0067] FRICTION MODIFIERS: In some embodiments, the durable lubricating and cooling fluid contains one or more friction modifiers. Suitable additional friction modifiers may comprise metal containing and metal-free friction modifiers and may include, but are not limited to, imidazolines, amides, amines, succinimides, alkoxylated amines, alkoxylated ether amines, amine oxides, amidoamines, nitriles, betaines, quaternary amines, imines, amine salts, amino guanidine, alkanolamides, phosphonates, metal-containing compounds, glycerol esters, sulfurized fatty compounds and olefins, sunflower oil other naturally occurring plant or animal oils, dicarboxylic acid esters, esters or partial esters of a polyol and one or more aliphatic or aromatic carboxylic acids, and the like.

[0068] Suitable friction modifiers may contain hydrocarbyl groups that are selected from straight chain, branched chain, or aromatic hydrocarbyl groups or mixtures thereof, and such hydrocarbyl groups may be saturated or unsaturated. The hydrocarbyl groups may be composed of carbon and hydrogen or hetero atoms such as sulfur or oxygen. The hydrocarbyl groups may range from 12 to 25 carbon atoms. In some embodiments the friction modifier may be a long chain fatty acid ester. In another embodiment the long chain fatty acid ester may be a monoester, or a di-ester, or a (tri)glyceride. The friction modifier may be a long chain fatty amide, a long chain fatty ester, a long chain fatty epoxide derivative, or a long chain imidazoline.

[0069] Other suitable friction modifiers may include organic, ashless (metal-free), nitrogen-free organic friction modifiers. Such friction modifiers may include esters formed by reacting carboxylic acids and anhydrides with alkanols and generally include a polar terminal group (e.g. carboxyl or hydroxyl) covalently bonded to an oleophilic hydrocarbon chain. An example of an organic ashless nitrogen-free friction modifier is known generally as glycerol monooleate (GMO) which may contain mono-, di-, and tri-esters of oleic acid. Other suitable friction modifiers are described in U.S. Pat. No. 6,723,685.

[0070] Aminic friction modifiers may include amines or polyamines. Such compounds can have hydrocarbyl groups that are linear, either saturated or unsaturated, or a mixture thereof and may contain from 12 to 25 carbon atoms. Further examples of suitable friction modifiers include alkoxylated amines and alkoxylated ether amines. Such compounds may have hydrocarbyl groups that are linear, either saturated, unsaturated, or a mixture thereof. They may contain from about 12 to about 25 carbon atoms. Examples include ethoxylated amines and ethoxylated ether amines.

[0071] The amines and amides may be used as such or in the form of an adduct or reaction product with a boron compound such as a boric oxide, boron halide, metaborate, boric acid or a mono-, di- or tri-alkyl borate. Other suitable friction modifiers are described in U.S. Pat. No. 6,300,291.

[0072] If the additional friction modifiers contain nitrogen, such additional friction modifiers may be present in the lubricating and cooling fluid in an amount to deliver up to about 200 ppm nitrogen, or up to about 150 ppm nitrogen, or about 100 to about 150 ppm nitrogen.

[0073] DETERGENTS: Metal detergents that may be included in the durable lubricating and cooling fluid described herein may generally comprise a polar head with a long hydrophobic tail where the polar head comprises a metal salt of an acidic organic compound. The salts may contain a substantially stoichiometric amount of the metal, in which case they are usually described as normal or neutral salts, and would typically have a total base number or TBN (as measured by ASTM D2896) of from 0 to less than 150. Large amounts of a metal base may be included by reacting an excess of a metal compound such as an oxide or hydroxide with an acidic gas such as carbon dioxide. The resulting overbased detergent comprises micelles of neutralized detergent surrounding a core of inorganic metal base (e.g., hydrated carbonates). Such overbased detergents may have a TBN of 150 or greater, such as from 150 to 450 or more.

[0074] Detergents that may be suitable for use in the present embodiments include oil-soluble overbased, low base, and neutral sulfonates, phenates, sulfurized phenates, and salicylates of a metal, particularly the alkali or alkaline earth metals, e.g., sodium, potassium, lithium, calcium, and magnesium. More than one metal may be present, for example, both calcium and magnesium. Mixtures of calcium and/or magnesium with sodium may also be suitable. Suitable metal detergents may be overbased calcium or magnesium sulfonates having a TBN of from 150 to 450 TBN, overbased calcium or magnesium phenates or sulfurized phenates having a TBN of from 150 to 300 TBN, and overbased calcium or magnesium salicylates having a TBN of from 130 to 350. Mixtures of such salts may also be used.

[0075] The metal-containing detergent may be present in the lubricating and cooling fluid in an amount sufficient to improve the anti-rust performance of the fluid. The metal-containing detergent may be present in the fluid in an amount sufficient to provide up to 300 ppm alkali and/or alkaline earth metal based on a total weight of the lubricating and cooling fluid. In one example, the metal-containing detergent may be present in an amount sufficient to provide from about 100 to about 300 ppm alkali and/or alkaline earth metal. In another embodiment, the metal-containing detergent may be present in an amount sufficient to provide from about 220 to about 250 ppm alkali and/or alkaline earth metal.

[0076] CORROSION INHIBITORS: Rust or corrosion inhibitors may also be included in the durable lubricating compositions described herein. Such materials include monocarboxylic acids and polycarboxylic acids. Examples of suitable monocarboxylic acids are octanoic acid, decanoic acid and dodecanoic acid. Suitable polycarboxylic acids include dimer and trimer acids such as are produced from such acids as tall oil fatty acids, oleic acid, linoleic acid, or the like.

[0077] Another useful type of rust inhibitor may be alkenyl succinic acid and alkenyl succinic anhydride corrosion inhibitors such as, for example, tetrapropenylsuccinic acid, tetrapropenylsuccinic anhydride, tetradecenylsuccinic acid, tetradecenylsuccinic anhydride, hexadecenylsuccinic acid, hexadecenylsuccinic anhydride, and the like. Also useful are the half esters of alkenyl succinic acids having 8 to 24 carbon atoms in the alkenyl group with alcohols such as the polyglycols. Other suitable rust or corrosion inhibitors include ether amines, acid phosphates, amines, polyethoxylated compounds such as ethoxylated amines, ethoxylated phenols, and ethoxylated alcohols, imidazolines, aminosuccinic acids or derivatives thereof, and the like. Mixtures of such rust or corrosion inhibitors may be used. The total amount of corrosion inhibitor, when present in the lubricating composition described herein may range up to 2.0 wt % or from 0.01 to 1.0 wt % based on the total weight of the lubricating composition.

[0078] VISCOSITY MODIFIERS: The durable lubricating and cooling fluid may optionally contain one or more viscosity modifiers. Suitable viscosity modifiers may include polyolefins, olefin copolymers, ethylene/propylene copolymers, polyisobutenes, hydrogenated styrene-isoprene polymers, styrene/maleic ester copolymers, hydrogenated styrene/butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkyl styrenes, hydrogenated alkenyl aryl conjugated diene copolymers, or mixtures thereof. Viscosity modifiers may include star polymers and suitable examples are described in US Publication No. 2012/0101017 A1.

[0079] The lubricating and cooling fluid described herein also may optionally contain one or more dispersant viscosity modifiers in addition to a viscosity modifier or in lieu of a viscosity modifier. Suitable dispersant viscosity modifiers may include functionalized polyolefins, for example, ethylene-propylene copolymers that have been functionalized with the reaction product of an acylating agent (such as maleic anhydride) and an amine; polymethacrylates functionalized with an amine, or esterified maleic anhydride-styrene copolymers reacted with an amine.

[0080] The total amount of viscosity modifier and/or dispersant viscosity modifier, when present, may be up to about 1.0 wt %, or up to about 0.5 wt %, or up to about 0.3 wt % based on the total weight of the lubricating and cooling fluid.

[0081] DEMULSIFIERS: Demulsifiers include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof, including polyethylene oxides, polypropylene oxides and (ethylene oxide-propylene oxide) polymers. When present, the amount of demulsifier in the lubricating and cooling fluid may be up about 0.05 wt, or up to about 0.02 wt %, or below about 0.015 wt % based on the total weight of the lubricating and cooling fluid.

[0082] ANTIFOAM AGENTS: Antifoam agents used to reduce or prevent the formation of stable foam include silicones, polyacrylates, or organic polymers. Foam inhibitors that may be useful in the compositions of the disclosed invention include polysiloxanes, copolymers of ethyl acrylate and 2-ethylhexylacrylate and optionally vinyl acetate. When present, the amount of antifoam in the lubricating and cooling fluid may be up about 0.1 wt, or up to about 0.08 wt %, or below about 0.07 wt % based on the total weight of the lubricating and cooling fluid.

[0083] POUR POINT DEPRESSANTS: The durable lubricating and cooling fluid may optionally contain one or more pour point depressants. Suitable pour point depressants may include esters of maleic anhydride-styrene, polymethacrylates, polymethylmethacrylates, polyacrylates or polyacrylamides or mixtures thereof. Pour point depressants, when present, may be present in amount from about 0.001 wt % to about 0.04 wt %, based upon the total weight of the lubricating and cooling fluid.

[0084] In general terms, a suitable durable lubricating and cooling fluid described herein may include additive components in the ranges listed in Table 2.

TABLE-US-00002 TABLE 2 Wt % Wt % (Suitable (Preferred Component Embodiments) Embodiments) Nitrogen System 3.0-8.0 5.0-7.0 Sulfur Component 0.05-1.5 0.5-1.0 Phosphorus System 0.3-0.7 0.4-0.6 Detergent(s) 0.05-0.5 0.1-0.3 Antioxidant(s) 0.1-0.6 0.3-0.5 Antifoaming agent(s) 0-0.05 0.1-0.04 Viscosity index improver(s) 0-7.0 0-5.0 Base oil(s) Balance Balance Total 100 100

[0085] The percentages of each component above represent the weight percent of each component, based upon the total weight of the lubricating and cooling fluid containing the recited component. Additives used in formulating the compositions described herein may be blended into the base oil individually or in various sub-combinations. However, it may be suitable to blend all of the components concurrently using an additive concentrate (i.e., additives plus a diluent, such as a hydrocarbon solvent). The use of an additive concentrate takes advantage of the mutual compatibility afforded by the combination of ingredients when in the form of an additive concentrate. Also, the use of a concentrate reduces blending time and lessens the possibility of blending errors.

[0086] Electric motor systems including a single fluid that provides not only lubrication to gears, clutches, and other mechanical parts but also cooling to the electric motor should provide good wear and friction performance, and relatively low electrical conductivity. However, the elevated temperatures in the electric motor pose challenges for developing this type of fluid. In the sump of the electric motor, the lubricating and cooling fluid can reach temperatures greater than about 70 C. or greater than about 100 C. and, in some instances, about 70 C. to about 135 C. Likewise, the temperature of the copper windings in the stator of the motor may reach at least about 150 C., and in some instances up to 180 C. with peak temperatures up to 230 C. Additives that provide elements like sulfur, boron, or phosphorus to achieve good wear performance, but can lead to excessive copper corrosion and higher conductivity. Moreover, these negative effects are exacerbated at higher temperatures. Thus, it was unexpected that the combination of selected additives providing amounts of sulfur, phosphorus, and boron herein provided acceptable wear and friction performance while also providing low copper corrosion and low conductivity at elevated temperatures.

[0087] In any of the embodiments herein, fluids including the sulfur system, the nitrogen system, and the phosphorus system as described herein and when used with an oil of lubricating viscosity including an API Group III base oil, or an API Group IV base oil, or mixtures thereof may exhibit one or more of the following: a pt-static friction performance of between about 0.101 to about 0.115 as measured according to MB10-10N (Reibwerttest im Getriebekomponenten-Prfstand zur Absicherung der Chargenqualitt von Getriebelen mit Additiven; an electrical conductivity of 80 nS/m or less (as measured according DIN 51111 (modified at 20 Hz at 100 C.)); a FZG failure load stage rating of 7 or higher at 90 C. (CEC L-84); and/or passing durability testing performed pursuant to the MB Pumptest (or equivalent) available at APL Automobil-Prftechnik Landau testing facility (or other suitable testing facility).

Selected Definitions

[0088] The following definitions of terms are provided in order to clarify the meanings of certain terms as used herein.

[0089] The terms lubricating oil, lubricant composition, lubricating composition, lubricant and lubricating and cooling fluid refer to a finished lubrication product comprising a major amount of a base oil plus a minor amount of an additive composition.

[0090] As used herein, the terms additive package, additive concentrate, additive composition, and transmission fluid additive package refer the portion of the lubricating oil composition excluding the major amount of base oil.

[0091] As used herein, the term hydrocarbyl substituent or hydrocarbyl group is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having a predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from hydrocarbon substituents, and substituted hydrocarbon substituents containing one or more of halo groups, hydroxyl groups, alkoxy groups, mercapto groups, nitro groups, nitroso groups, amino groups, pyridyl groups, furyl groups, imidazolyl groups, oxygen and nitrogen, and wherein no more than two non-hydrocarbon substituents are present for every ten carbon atoms in the hydrocarbyl group.

[0092] As used herein, the term percent by weight or wt %, unless expressly stated otherwise, means the percentage the recited component represents to the weight of the entire composition.

[0093] The terms soluble, oil-soluble, or dispersible used herein may, but does not necessarily, indicate that the compounds or additives are soluble, dissolvable, miscible, or capable of being suspended in the oil in all proportions. The foregoing terms do mean, however, that they are, for instance, soluble, suspendable, dissolvable, or stably dispersible in oil to an extent sufficient to exert their intended effect in the environment in which the oil is employed. Moreover, the additional incorporation of other additives may also permit incorporation of higher levels of a particular additive, if desired.

[0094] The term alkyl as employed herein refers to straight, branched, cyclic, and/or substituted saturated chain moieties from about 1 to about 200 carbon atoms.

[0095] The term alkenyl as employed herein refers to straight, branched, cyclic, and/or substituted unsaturated chain moieties from about 3 to about 30 carbon atoms.

[0096] The term aryl as employed herein refers to single and multi-ring aromatic compounds that may include alkyl, alkenyl, alkylaryl, amino, hydroxyl, alkoxy, halo substituents, and/or heteroatoms including, but not limited to, nitrogen, and oxygen.

[0097] As used herein, the average number molecular weight or Mn is determined by gel permeation chromatography (GPC) using commercially available polystyrene standards (with a Mn of about 180 to about 18,000 as the calibration reference). The weight average molecular weight (Mw) and the number average molecular weight (Mn) may be determined with a gel permeation chromatography (GPC) instrument obtained from Waters or the like instrument and the data processed with Waters Empower Software or the like software. The GPC instrument may be equipped with a Waters Separations Module and Waters Refractive Index detector (or the like optional equipment). The GPC operating conditions may include a guard column, 4 Agilent PLgel columns (length of 3007.5 mm; particle size of 5, and pore size ranging from 100-10000 ) with the column temperature at about 40 C. Un-stabilized HPLC grade tetrahydrofuran (THF) may be used as solvent, at a flow rate of 1.0 mL/min. The GPC instrument may be calibrated with commercially available poly(methyl methacrylate) (PMMA) standards having a narrow molecular weight distribution ranging from 960-1,568,000 g/mol. The calibration curve can be extrapolated for samples having a mass less than 500 g/mol. Samples and PMMA standards can be in dissolved in THE and prepared at concentration of 0.1 to 0.5 wt. % and used without filtration. GPC measurements are also described in U.S. Pat. No. 5,266,223, which is incorporated herein by reference. The GPC method additionally provides molecular weight distribution information; see, for example, W. W. Yau, J. J. Kirkland and D. D. Bly, Modern Size Exclusion Liquid Chromatography, John Wiley and Sons, New York, 1979, also incorporated herein by reference.

[0098] It is to be understood that throughout the present disclosure, the terms comprises, includes, contains, etc. are considered open-ended and include any element, step, or ingredient not explicitly listed. The phrase consists essentially of is meant to include any expressly listed element, step, or ingredient and any additional elements, steps, or ingredients that do not materially affect the basic and novel aspects of the invention. The present disclosure also contemplates that any composition described using the terms, comprises, includes, contains, is also to be interpreted as including a disclosure of the same composition consisting essentially of or consisting of the specifically listed components thereof.

EXAMPLES

[0099] The following non-limiting examples illustrate the features and advantages of one or more embodiments of the disclosure. In these examples, as well as elsewhere in this application, all ratios, parts, and percentages are by weight unless otherwise indicated. Any discussion of a test method or other standardized test method noted in the Examples, disclosure, or claims, unless apparent from the context of its use, refers to the version of the test method publicly available at the time of the filing of the present disclosure. To demonstrate how the sulfur system, nitrogen system, and antiwear system affected the wear, friction and conductivity of the fluid, exemplary finished fluids were formulated and tested.

Example 1

[0100] Various lubricating formulations were evaluated for FZG Scuffing, friction performance electrical conductivity, and durability of the auxiliary pumping system. The evaluations were as follows:

[0101] FZG Scuffing Test is wear test used to evaluate the scuffing load capacity of lubricants and is performed according to CEC L-84 at 90 C. Results are reported in load stage failure, and better results are obtained for samples with a higher load stage failure with acceptable performance being a load stage failure of 7 or higher.

[0102] It is beneficial for electric motor fluids to exhibit low electrical conductivity, and thus act somewhat as an insulator. The conductivity of fluids was measured according to modified DIN 51111 (at 20 Hz at 100 C.). Acceptable electrical conductivity is 80 nS/m or less at 100 C.

[0103] Friction performance was evaluated as pt-static friction performance of about 0.101 to about 0.115 as measured according to MB10-10N (Reibwerttest im Getriebekomponenten-Prfstand zur Absicherung der Chargenqualitt von Getriebelen mit Additiven).

[0104] Pump durability is a wear test evaluated using the MB Pumptest (or equivalent) available at APL Automobil-Prftechnik Landau testing facility (or other suitable testing facility).

[0105] The formulations tested in Table 3 below all contained the same additive base pack containing antioxidant, friction modifiers, detergent, antifoam and demulsifier. The formulations also contained varying amounts of sulfurized components, nitrogen-containing dispersants, phosphorus antiwear additives, and base oil as set forth in Table 3. The formulations were tested in multiple base oils to obtain finished fluids having kinematic viscosities at 100 C. of between 3.6 and 4.2 cSt. The inventive formulation contained similar additives to the comparative formulations but balanced the delivery of sulfur, nitrogen, and phosphorus differently to achieve surprisingly improved wear, friction, pump durability and low conductivity. Details of the various fluid components are described below:

[0106] Sulfur Component S-1: 2,5-dimercapto-1,3,4-thiadiazole and hydrocarbyl-substituted derivatives thereof containing about 35 wt % sulfur, which was a 75:25 to 85:15 mixture of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole.

[0107] Sulfur Component S-2: sulfurized synthetic sperm oil comprised of sulfurized transesterified triglycerides containing about 6.8 wt % sulfur.

[0108] Dispersant D-1: phosphorylated and borated succinimide dispersant made from a 950 Mn polyisobutylene, maleic anhydride, a mixture of polyalkylene polyamines having an average of 6.5 nitrogen atoms per molecule, phosphorous acid, and boric acid. This dispersant has about 0.8 wt % phosphorus, about 0.4 wt % boron, and about 1.8% nitrogen.

[0109] Dispersant D-2: phosphorylated and borated succinimide dispersant obtained from a 2300 Mn polyisobutylene, maleic anhydride, a mixture of polyalkylene polyamines having an average of 6.5 nitrogen atoms per molecule, phosphorous acid, and boric acid. The dispersant had about 0.8 wt % nitrogen, about 0.2 wt % boron, and about 0.4 wt % phosphorus.

[0110] Dispersant D-3: succinimide dispersant obtained from 950 Mn polyisobutylene, maleic anhydride, and a mixture of polyalkylene polyamines having an average of 6.5 nitrogen atoms per molecule. The dispersant has approximately 2.1 wt % nitrogen.

[0111] Phosphorus P-1: tris(2-ethylhexyl) phosphate (containing about 7 wt % phosphorus).

[0112] Phosphorus P-2: 3-[[bis(2-methylpropoxy) phosphinothioy]thio]-2-methyl-propanoic acid (containing about 9 wt % phosphorus).

[0113] Phosphorus P-3: Amine salt of a phosphoric acid ester including a mixture of dihexyl and monohexyl phosphate with di and/or trialkylated amines having alkyl groups of C12 to C14 (containing about 4.9 weight percent phosphorus).

[0114] Base Oils: Base Oils included a mixture of GTLs and traditional Group III base oils having a kV100 of approximately 3 cSt and approximately 4 cSt oils to achieve finished fluid viscosity targets.

TABLE-US-00003 TABLE 3 Fluid Compositions C-1 C-2 C-3 I-1 C-4 C-5 S-1 (wt %) 0.35 0.35 0.35 0.45 0.45 0.45 S-2 (wt %) 0.4 0.4 0.4 0.4 P-1 (wt %) 0.7 0.7 0.7 P-2 (wt %) 0.06 0.06 0.06 0.06 P-3 (wt %) 0.3 0.3 0.3 0.3 D-1 (wt %) 3.0 D-2 (wt %) 6.0 6.0 6.0 6.0 3.0 6.0 D-3 (wt %) 0.5 0.5 0.5 0.5 0.5 GTL Base Oil (wt %) 80 80 80 80 74.3 79.3 GTL Base Oil (wt %) 10 10 10 10 15.0 9.9 kV100, cSt 3.6 3.6 3.6 3.6 3.6 3.6

TABLE-US-00004 TABLE 4 Calculated Elemental Analysis of Fluids C-1 C-2 C-3 I-1 C-4 C-5 S-1, ppm Sulfur 1225 1225 1225 1575 1575 1575 S-2, ppm Sulfur 272 272 272 272 Total Sulfur from S-1 and S-2, ppm 1497 1225 1497 1847 1847 1575 P-1, ppm Phosphorus 490 490 490 P-2, ppm Phosphorus 54 54 54 54 P-3, ppm Phosphorus 147 147 147 147 Total Phosphorus P-1, P-2, and P-3, ppm 54 147 691 691 691 D-1, ppm Nitrogen 540 D-2, ppm Nitrogen 480 480 480 480 240 480 D-3, ppm Nitrogen 105 105 105 105 105 Boron from Dispersant system, ppm 120 120 120 120 180 120 Phosphorus from Dispersant system, ppm 240 240 240 240 360 240 Total Nitrogen fromDispersant system, ppm 480 480 480 480 780 480 (B + P)/N from Dispersant System 0.75 0.75 0.75 0.75 0.69 0.75 Total Phosphorus 240 294 387 931 1051 931 % phosphorus from P-1 52.6 46.6 52.6 % phosphorus from P-2 18.4 5.8 5.1 5.8 % phosphorus from P-3 38.0 15.7 14.0 15.7 P/S 0.13 0.17 0.22 0.44 0.5 0.59

TABLE-US-00005 TABLE 5 Fluid Performance (failing results are underlined) C-1 C-2 C-3 I-1 C-4 C-5 FZG, FLS 7 7 6 7 7 7 Friction Performance: - 0.112 0.115 0.109 0.110 0.108 static as measured according to MB10-10N Electrical 63 65 Conductivity, nS/m Pump durability Fail Fail Fail Pass Fail Fail performed per pursuant to the MB Pumptest

[0115] As shown in Table 5, comparative fluids C-1 to C-3 had unacceptable pump durability even though C-2 exhibited acceptable electrical conductivity (i.e., less than 80 nS/m at 100 C.). Inventive fluid I-1 with the discovered selection of the sulfur system, the nitrogen system, and the phosphorus antiwear system was capable of balancing wear, friction performance, electrical conductivity, and pump durability. Notably, comparative fluids C-4 and C-5, even with the three antiwear phosphorus additives from the inventive fluid in a phosphorus system, could not pass the pump durability tests because this fluid did not have the correct balance of sulfur and nitrogen together with the noted phosphorus antiwear additives. Only fluids have the discovered blends of the sulfur system, the nitrogen system, and the phosphorus antiwear system can achieve acceptable performance in wear, conductivity, and durability at the same time.

[0116] It is to be understood that while the lubricating composition and compositions of this disclosure have been described in conjunction with the detailed description thereof and summary herein, the foregoing description is intended to illustrate and not limit the scope of the disclosure, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the claims. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims.

[0117] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. As used throughout the specification and claims, a and/or an may refer to one or more than one. Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, percent, ratio, reaction conditions, and so forth used in the specification are to be understood as being modified in all instances by the term about, whether or not the term about is present. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0118] It is to be understood that each component, compound, substituent or parameter disclosed herein is to be interpreted as being disclosed for use alone or in combination with one or more of each and every other component, compound, substituent or parameter disclosed herein.

[0119] It is further understood that each range disclosed herein is to be interpreted as a disclosure of each specific value within the disclosed range that has the same number of significant digits. Thus, a range of from 1 to 4 is to be interpreted as an express disclosure of the values 1, 2, 3 and 4 as well as any range of such values such as 1 to 4, 1 to 3, 1 to 2, 2 to 4, 2 to 3 and so forth.

[0120] It is further understood that each lower limit of each range disclosed herein is to be interpreted as disclosed in combination with each upper limit of each range and each specific value within each range disclosed herein for the same component, compounds, substituent or parameter. Thus, this disclosure to be interpreted as a disclosure of all ranges derived by combining each lower limit of each range with each upper limit of each range or with each specific value within each range, or by combining each upper limit of each range with each specific value within each range.

[0121] Furthermore, specific amounts/values of a component, compound, substituent or parameter disclosed in the description or an example is to be interpreted as a disclosure of either a lower or an upper limit of a range and thus can be combined with any other lower or upper limit of a range or specific amount/value for the same component, compound, substituent or parameter disclosed elsewhere in the application to form a range for that component, compound, substituent or parameter.