Lubricating and cooling fluid for an electric motor system

Abstract

A lubricating and cooling fluid for an electric motor system comprising a lubricating base oil, at least one sulfurized component, a dispersant system comprising at least two dispersants, and a friction modifier system comprising at least two friction modifiers. The lubricating and cooling fluid provides good wear and friction performance and good copper corrosion and conductivity for an electric motor system.

Description

[0001] Cross-references to related applications

[0002] This disclosure claims the benefit of priority to U.S. Application 17 / 206,888, filed March 19, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a lubricating and cooling fluid for an electric motor system and a method for lubricating gears and clutches and cooling the motor in an electric motor system. Specifically, the disclosed method and fluid relate to a lubricating and cooling fluid for electric vehicles, the lubricating and cooling fluid comprising an oil having a lubricating viscosity, a vulcanizing component, a dispersant system comprising at least two dispersants, and a friction modifier system comprising at least three friction modifiers. Background Technology

[0004] In electric vehicle powertrains, where the electric motor is the sole drive source, a single lubricant may be required to lubricate the gears and clutches and cool the electric motor. A major challenge in developing these types of lubricants is achieving wear resistance, tribological properties, and oxidation stability, while ensuring compatibility with the electrically driven components in the powertrain. For example, the lubricant must provide good wear protection and tribological properties for both the gears and clutches within the electric vehicle powertrain. However, because the lubricant is also used to cool the electric motor (e.g., by contacting the copper windings in the stator operating at high temperatures), it must also provide copper corrosion protection and have relatively low electrical conductivity to suppress static buildup and discharge in the electrically driven components.

[0005] Despite advancements in lubricant technology for electric vehicle powertrains, there remains a need for electric vehicle powertrain lubricant compositions that offer desirable wear resistance, oxidation stability, copper corrosion inhibition, and / or relatively low lubricant conductivity. Summary of the Invention

[0006] In one embodiment, the present disclosure provides a method for lubricating gears and clutches in an electric motor system and simultaneously cooling an electric motor thereof. The method includes operating an electric motor system comprising a lubricating and cooling fluid such that the temperature of the lubricating and cooling fluid in a sump of the electric motor system is from about 70 °C to about 125 °C and the temperature of copper windings in a stator of the electric motor system is between 150 °C to about 180 °C; lubricating gears and clutches in the electric motor system with the lubricating and cooling fluid and simultaneously cooling the electric motor in the electric motor system by contacting the copper windings with the lubricating and cooling fluid; and wherein the lubricating and cooling fluid comprises an oil having a lubricating viscosity, the oil having a lubricating viscosity including an API Group III base oil, an API Group IV base oil, or a mixture thereof; at least one thiadiazole or hydrocarbyl-substituted derivative thereof, the at least one thiadiazole or hydrocarbyl-substituted derivative thereof delivering from about 1000 ppm to about 1500 ppm of sulfur to the lubricating fluid; a dispersant system comprising (i) a first dispersant obtained from a polyisobutylene having a number average molecular weight of from about 1500 to about 2500 and delivering up to about 700 ppm of nitrogen to the lubricating and cooling fluid and (ii) a second dispersant having a number average molecular weight of about 1000 or less and delivering up to about 150 ppm of nitrogen to the lubricating fluid; an alkoxylated aliphatic amine, the alkoxylated aliphatic amine delivering up to about 20 ppm of nitrogen to the lubricating and cooling fluid; an ether amine, the ether amine delivering up to about 20 ppm of nitrogen to the lubricating and cooling fluid.

[0007] In some methods or embodiments, at least one of the first dispersant and the second dispersant is boronated and phosphonated such that the total amount of boron and phosphorus in the dispersant system is from about 0.5 to about 0.7 relative to the nitrogen in the dispersant system, and wherein the first dispersant and the second dispersant deliver up to about 100 ppm of total boron and phosphorus per 1000 number average molecular weight of the combined polyisobutylene used to obtain the first dispersant and the second dispersant.

[0008] In other methods or embodiments, the lubricating and cooling fluid used in any of the above methods can include any combination of the optional features. These embodiments can include that the at least one thiadiazole or hydrocarbyl-substituted derivative thereof includes one or more compounds having the structure of Formula I:

[0009]

[0010] wherein each R1 is independently hydrogen or sulfur; each R2 is independently an alkyl group; n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, n of the adjacent R2 moiety is 1; and wherein at least one R1 is sulfur; and / or wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof is a mixture of hydrocarbyl-substituted derivatives of 2,5-dimercapto-l,3,4-thiadiazole, including one of 2,5-bis-(nonyldithio)-l,3,4-thiadiazole, 2,5-mono-(nonyldithio)-l,3,4-thiadiazole, or combinations thereof; and / or wherein the lubricating and cooling fluid further comprises a fatty diamine delivering up to about 3 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the alkoxylated fatty amines, ether amines, and fatty diamines deliver up to about 30 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the alkoxylated fatty amines are di(hydroxyalkyl) fatty tertiary amines comprising hydroxyalkyl groups each containing 2 to 4 carbon atoms and further comprising acyclic hydrocarbyl groups containing 16 to 25 carbon atoms; and / or wherein the ether amines include isodecyloxypropylamine; and / or wherein the fatty diamines include n-oleyl-l,3-diaminopropane; and / or wherein the alkoxylated fatty amines and ether amines each deliver up to about 15 ppm of nitrogen to the lubricating and cooling fluid, and wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof is a thiadiazole mixture of hydrocarbyl-substituted derivatives of 2,5-dimercapto-l,3,4-thiadiazole, including one of 2,5-bis-(nonyldithio)-l,3,4-thiadiazole, 2,5-mono-(nonyldithio)-l,3,4-thiadiazole, or combinations thereof, and wherein the thiadiazole mixture and the optional sulfidated ester deliver about 1400 ppm to about 1800 ppm of sulfur to the lubricating and cooling fluid.

[0011] In yet further methods or embodiments, the lubricating and cooling fluid used in any of the above methods can further comprise a first dispersant present in an amount to deliver up to about 500 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the second dispersant is present in an amount to deliver about 115 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the first dispersant is obtained from a polyisobutylene having a number average molecular weight of about 2000 to about 2400, and the second dispersant is obtained from a polyisobutylene having a number average molecular weight of about 950; and / or wherein the first dispersant is present in an amount to deliver up to about 100 ppm of boron and up to about 250 ppm of phosphorus to the lubricating and cooling fluid; and / or wherein the lubricating fluid has a sulfurized ester that delivers about 180 ppm to about 300 ppm of sulfur to the lubricating and cooling fluid; and / or wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof and the sulfurized ester deliver about 1400 ppm to about 1800 ppm of sulfur to the lubricating fluid; and / or wherein the sulfurized ester comprises a transesterified triglyceride.

[0012] In embodiments, the lubricating and cooling fluid used in any of the methods herein can comprise a Group III base oil; and / or a gas-to-liquid (GTL) base oil; and / or a polyalphaolefin (PAO) base oil.

[0013] In still other embodiments, the lubricating and cooling fluid used in any of the methods herein can have an initial conductivity of about 60 nS / M or less, as measured by modified ASTM D2624-15 using the lubricating and cooling fluid and measured at 20 Hz and 100 °C.

[0014] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein.

[0015] The following term definitions are provided in order to clarify the meaning of certain terms as used herein.

[0016] The terms "lubricating oil", "lubricant composition", "lubricating composition", "lubricant", and "lubricating and cooling fluid" mean a finished lubricating product comprising a major amount of a base oil and a minor amount of an additive composition.

[0017] As used herein, the terms "additive package", "additive concentrate", "additive composition", and "transmission fluid additive package" mean the portion of a lubricating oil composition that does not include a major amount of a base oil.

[0018] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense by those of ordinary skill in the art. Specifically, it refers to a group having carbon atoms directly connected to the rest of the molecule and predominantly having the characteristics of a hydrocarbon. Each hydrocarbyl group is independently selected from hydrocarbon substituents and substituted hydrocarbon substituents containing one or more halogen groups, hydroxyl groups, alkoxy groups, thiol groups, nitro groups, nitroso groups, amino groups, pyridyl groups, furanyl groups, imidazolyl groups, oxygen, and nitrogen, and wherein there are no more than two non-hydrocarbon substituents for each ten carbon atoms in the hydrocarbyl group.

[0019] As used herein, unless otherwise expressly stated, the term "weight percent" or "wt%" means the percentage of the component by weight of the entire composition.

[0020] The terms "soluble," "oil soluble," or "dispersible" as used herein can, but do not necessarily, mean that the compound or additive is soluble, dissolvable, miscible, or capable of being suspended in oil in all proportions. However, the foregoing terms do mean that they are soluble, suspendable, dissolvable, or stably dispersible in oil, for example, to an extent sufficient to perform their intended function in an environment employing oil. In addition, additional incorporation of other additives can also allow incorporation of higher levels of a particular additive, if desired.

[0021] As employed herein, the term "alkyl" refers to a straight chain, branched chain, cyclic, and / or substituted saturated chain moiety of from about 1 to about 200 carbon atoms.

[0022] As employed herein, the term "alkenyl" refers to a straight chain, branched chain, cyclic, and / or substituted unsaturated chain moiety of from about 3 to about 30 carbon atoms.

[0023] As employed herein, the term "aryl" refers to monocyclic and polycyclic aromatic compounds, which can include alkyl, alkenyl, alkylaryl, amino, hydroxyl, alkoxy, halogen substituents, and / or heteroatoms including, but not limited to, nitrogen and oxygen.

[0024] As used herein, "number average molecular weight" or "Mn" is determined by gel permeation chromatography (GPC) using commercially available polystyrene standards, wherein the Mn is from about 180 to about 18,000 as a calibration reference.

[0025] It should be understood throughout the disclosure that the terms "comprising," "including," "containing," etc. are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") and are intended to cover any and all elements, steps, or components associated with the described compositions, processes, and methods. Likewise, the term "comprising" is used in the claims to mean "including but not limited to." The phrase "consisting essentially of" means including any explicitly listed elements, steps, or components and any other elements, steps, or components that do not materially affect the basic and novel characteristics of the invention. The disclosure also contemplates the BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a plot of electrical conductivity versus sulfur, phosphorus, and dispersant PIB chain length;

[0027] Figures 2 to 4 is a plot of dynamic friction coefficient measured on a clutch test stand;

[0028] Figures 5 to 6 is a plot of static friction coefficient measured on a clutch test stand;

[0029] Figure 7 is a plot of torque-V shift behavior measured on a clutch test stand;

[0030] Figures 8 to 9 is a plot of synchronization friction value measured on a SSP 180 test stand;

[0031] Figure 10 is a plot of electrical resistance versus temperature measured on a conductivity meter; and

[0032] Figure 11 is a plot of loss factor (tan delta) versus temperature measured on a conductivity meter. DETAILED DESCRIPTION

[0033] According to one exemplary embodiment, a lubricating and cooling fluid for an electric motor system includes a lubricating base oil of an API Group III base oil, an API Group IV base oil, or a mixture thereof, at least one sulfurized component, a dispersant system including at least two dispersants, and a friction modifier system including at least two friction modifiers. The at least one sulfurized component includes a selected additive and an amount of sulfur to achieve a relatively low electrical conductivity and good copper corrosion performance. The two dispersants are selected to maintain a relatively low electrical conductivity even when providing components known to have high electrical conductivity. One of the dispersants has a relatively high number average molecular weight of about 1500 to about 2500, and the other dispersant has a relatively low number average molecular weight of less than about 1000. The friction modifier includes an alkoxylated aliphatic amine, an ether amine, and optionally a fatty diamine. In another embodiment, the lubricating and cooling fluid includes two sulfurized components. In any embodiment, the lubricating and cooling fluid has a kinematic viscosity at about 100°C of less than about 4.5 cSt (as measured by ASTM D2270-10), and / or has an initial electrical conductivity of less than about 60 nS / M (as measured by a modified version of ASTM D2624 described in more detail herein).

[0034] For fluids for electric motor systems that need to provide not only wear and friction performance, but also cooling, low copper corrosion, and low electrical conductivity, there are challenges in developing such robust fluids because elements and components containing sulfur, boron, and phosphorus traditionally used in internal combustion engines and transmissions can negatively impact copper corrosion and / or electrical conductivity. For example, sulfur can corrode copper, and phosphorus and boron can increase the electrical conductivity of the fluid. These undesirable effects are amplified at elevated temperatures. Therefore, electric motors and gears that operate at elevated temperatures require carefully developed fluids. For example, the fluid sump temperature of the electric motor systems described herein can reach about 70°C to about 125°C. Further, the temperature of the copper windings in the stator of the electric motor systems described herein can reach up to 180°C. At these elevated temperatures, additives in the fluid used to achieve good wear and friction performance can not favor maintaining the desired electrical conductivity and copper compatibility.

[0035] However, it is discovered herein that such elements can be provided into fluids for such electro-mobility ("e-mobility") applications if sulfur, phosphorous, and boron are provided by a unique combination of at least one sulfur component, a friction modifier system, and a dispersant system as described herein. In one method, for example, the at least one sulfur component includes a selected amount of a thiadiazole additive, the friction modifier system includes a selected amount of an aliphatic amine, an ether amine, and optionally a diamine, and the dispersant system includes a selected amount of at least two different dispersant additives. In one method, for example, at least one of the first dispersant and / or the second dispersant is boronated and phosphonated such that the total amount of boron and phosphorous in the dispersant system is about 0.5 to about 0.7 relative to the nitrogen in the dispersant system, and wherein the first dispersant and the second dispersant deliver a total boron and phosphorous of at most about 100 ppm per 1000 number average molecular weight of the combined polyisobutylene portion in the dispersant system.

[0036] In such compositions, the fluids herein result in an initial conductivity of less than about 60 nS / M, even with elements previously known to have a negative impact on conductivity, as measured by the modified version of ASTM D2624 described in more detail herein.

[0037] In another exemplary embodiment, the present disclosure is directed to a method of lubricating a gear and clutch in an electric motor system and simultaneously cooling an electric machine in the electric motor system. According to the method, an electric motor system comprising a lubricating and cooling fluid is operated such that the temperature of the lubricating and cooling fluid in the electric motor reaches at least about 70 °C in a sump of the electric motor system, and in other embodiments, the lubricating and cooling fluid in the sump of the electric motor system is from about 70 °C to about 125 °C. In another embodiment, the electric motor system comprising a lubricating and cooling fluid is operated such that the lubricating and cooling fluid contacts copper windings in a stator of the electric motor system and such that the copper windings reach a temperature of at least about 150 °C. In other embodiments, the electric motor system comprising a lubricating and cooling is operated such that the lubricating and cooling fluid contacts the copper windings and such that the copper windings reach a temperature of at least about 180 °C. The lubricating and cooling fluid used in the method comprises at least one lubricating base oil comprising an API Group III base oil, an API Group IV base oil, or a mixture thereof, at least one sulfurized component, a dispersant system comprising two dispersants, and a friction modifier system comprising at least two friction modifiers. One of the dispersants has a relatively high number average molecular weight of from about 1500 to about 2500. The other dispersant has a relatively low number average molecular weight of less than about 1000. The friction modifiers comprise an alkoxylated aliphatic amine and an ether amine. In an alternative embodiment, the lubricating and cooling fluid contains a fatty diamine as an additional friction modifier. In another embodiment, the lubricating and cooling fluid comprises two sulfurized components. In any of the above embodiments of the method, the lubricating and cooling fluid can have a kinematic viscosity at 100 °C of less than about 4.5 cSt (as measured by ASTM D2270-10) and has an initial conductivity of less than about 60 nS / M (as measured by a modified version of ASTM D2624 described in more detail herein). Any embodiment of the method herein can also include the ratios and relationships of boron, phosphorus, and nitrogen and / or the amounts relative to the molecular weights of the dispersants of the lubricating fluids for the method described above.

[0038] Base oil : The base oil suitable for formulating the lubricating and cooling fluid for electric vehicles according to the present disclosure can be selected from any of suitable synthetic or natural oils or mixtures thereof having a suitable lubricating viscosity. The natural oils can include animal and vegetable oils (e.g., castor oil, lard oil) and mineral oils such as liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oil of the paraffinic, naphthenic or mixed

[0039] The base oils used in the present invention described herein can be a single base oil or can be a mixture of two or more base oils. The base oil or oils can be selected from any of the base oils in Groups III through IV as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. These base oil groups are shown in Table 1 below:

[0040] Table 1

[0041]

[0042] In one variation, the base oil can 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 can be a mixture of two or more of the API Group III base oils or two or more of the API Group IV base oils.

[0043] The API Group III base oils can include oils derived from Fischer-Tropsch synthesized hydrocarbons. The Fischer-Tropsch synthesized hydrocarbons are made from synthesis gas containing H2 and CO using a Fischer-Tropsch catalyst. This hydrocarbon typically requires further processing to be used as a base oil. These types of oils are often referred to as gas-to-liquid (GTL). For example, the hydrocarbon can be hydroisomerized using the methods disclosed in U.S. Patent Nos. 6,103,099 or 6,180,575; hydrocracked and hydroisomerized using the methods disclosed in U.S. Patent Nos. 4,943,672 or 6,096,940; dewaxed using the methods disclosed in U.S. Patent No. 5,882,505; or hydroisomerized and dewaxed using the methods disclosed in U.S. Patent Nos. 6,013,171, 6,080,301; or 6,165,949.

[0044] The API Group IV base oils, PAOs, are typically derived from monomers having 4 to 30, or 4 to 20, or 6 to 16 carbon atoms. Examples of PAOs that can be used in the present invention include those derived from octene, decene, mixtures thereof, and the like. The PAOs can have a kinematic viscosity at 100°C of 2 to 15, or 3 to 12, or 4 to 8 cSt as measured by ASTM D2270-10. Examples of PAOs include a 4 cSt PAO at 100°C, a 6 cSt PAO at 100°C, and mixtures thereof.

[0045] The base oil is combined with the additive composition as disclosed in the embodiments herein to provide a lubricating and cooling fluid for use in an electric motor system having an electric motor, a gear, and a clutch. Thus, the base oil can be present in the lubricating and cooling fluids in an amount greater than about 80 weight percent, based on the total weight of the lubricating and cooling fluid. In some embodiments, the base oil can be present in the lubricating and cooling fluids in an amount greater than about 85 weight percent, based on the total weight of the lubricating and cooling fluid.

[0046] Additive Composition: The fluids herein comprise an additive composition comprising at least a sulfurized component, a friction modifier system or component, and a dispersant system or component. Each of these will be described below.

[0047] Sulfurized Component: The lubricating and cooling fluids comprise a balance of at least a first sulfurized component to improve wear performance and copper protection. Optionally, a second sulfurized component can also be used in some applications.

[0048] The first sulfurized component can be one or more thia- diazoles or hydrocarbyl-substituted derivatives thereof, or in other approaches, can be a mixture of thia-diazoles or hydrocarbyl-substituted derivatives thereof. Examples of thia-diazoles that can be used include 2,5-dimercapto-1,3,4-thia-diazole, 2-mercapto-5- hydrocarbylthio-1,3,4-thia-diazole, 2-mercapto-5- hydrocarbyldithio-1,3,4-thia-diazole, 2,5-bis(hydrocarbylthio)- 1,3,4-thia-diazole, or 2,5-bis(hydrocarbyldithio)-1,3,4-thia- diazole. 1,3,4-Thia-diazoles are typically synthesized from hydrazine and carbon disulfide by known methods. See, for example, U.S. Patents 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.

[0049] Surprisingly, the form and amount of the first sulfurized additive herein contributes to the ability of the fluid to maintain low electrical conductivity, lower copper corrosion, and at the same time meet other desired friction and wear performance characteristics. In approaches, the at least one thia-diazole or hydrocarbyl-substituted derivative thereof comprises one or more compounds having the structure of Formula I:

[0050]

[0051] wherein each R1 is independently hydrogen or sulfur, each R2 is independently an alkyl group, n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, n of the adjacent R2 moiety is 1, and with the proviso that at least one R1 is sulfur. In other approaches, the at least one thia-diazole or hydrocarbyl-substituted derivative thereof is a blend of compounds of Formula la and Formula lb as shown below:

[0052]

[0053] wherein within Formula la, each integer n is 1, each R1 is sulfur, and each R2 is a C5 to C15 alkyl group, preferably a C8 to C12 alkyl group; and

[0054]

[0055] wherein within formula Ib, one integer n is 1 and the associated R2group is a C5to C15alkyl group (preferably a C8to C12alkyl group), and the other integer n is 0 and both R1groups are sulfur. In some embodiments, the first vulcanization additive includes a blend of formulae Ia and Ib, where formula Ia is the majority in the blend, and in other approaches, the blend of Ia and Ib is about 75 wt% to about 90 wt% of Ia and about 10 wt% to about 25 wt% of Ib (or other ranges therebetween). In another approach, the first vulcanization additive is 2,5-dimercapto-1,3,4-thiadiazole, which includes 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%).

[0056] The at least one thiadiazole or hydrocarbyl-substituted derivative thereof is present in the lubricating and cooling fluid in an amount to deliver about 1000 ppm to about 1500 ppm sulfur, about 1200 ppm to about 1500 ppm sulfur, or about 1200 ppm to about 1300 ppm sulfur (or other ranges therebetween). In one embodiment, the at least one thiadiazole or hydrocarbyl-substituted derivative thereof is 2,5-dimercapto-1,3,4-thiadiazole, and the thiadiazole compound is present in the lubricating and cooling fluid in an amount to deliver about 1000 ppm to about 1500 ppm sulfur, about 1200 ppm to about 1500 ppm sulfur, or about 1200 ppm to about 1300 ppm sulfur (or other ranges therebetween).

[0057] As shown in the examples herein, when the first vulcanization component is present in the lubricating and cooling fluid in an amount to deliver about 1000 ppm to about 1500 ppm sulfur, about 1200 ppm to about 1500 ppm sulfur, or about 1200 ppm to about 1300 ppm sulfur (or other ranges therebetween), the resulting composition provides improved FZG scuffing scores and / or reduced copper corrosion. When the first vulcanization component is present in the lubricating and cooling fluid in an amount less than 1000 ppm sulfur or greater than 1500 ppm sulfur, the resulting composition provides poor FZG scuffing scores and / or increased copper corrosion.

[0058] The lubricating and cooling fluid can optionally include a second sulfurized 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 aforementioned animal or vegetable fats and oils with various alcohols; or mixtures thereof, by any suitable method. In one embodiment, the sulfurized component is a whale oil or synthetic whale oil and consists of triglycerides exchanged with sulfurized esters.

[0059] The optional sulfurized ester can be present in the lubricating and cooling fluid in an amount that delivers up to about 300 ppm of sulfur, about 200 ppm to about 300 ppm of sulfur, or about 225 ppm to about 275 ppm of sulfur (or other ranges therebetween). In one embodiment, the optional sulfurized ester is a sulfurized synthetic whale oil consisting of triglycerides exchanged with sulfurized esters and can be present in the lubricating and cooling fluid in an amount that delivers about 200 ppm to about 300 ppm of sulfur, or about 225 ppm to about 275 ppm of sulfur (or other ranges therebetween).

[0060] When both sulfurized components are present in the lubricating and cooling fluid, they are present in amounts that deliver a total sulfur in an amount of about 1400 ppm to about 1800 ppm of sulfur, or about 1400 ppm to about 1500 ppm of sulfur (or other ranges therebetween). In one embodiment, the first sulfurized component is 2,5-dimercapto-l,3,4-thiadiazole and / or hydrocarbyl-substituted derivatives thereof, and the optional second sulfurized component is a sulfurized synthetic whale oil consisting of triglycerides exchanged with sulfurized esters. In this embodiment, the first sulfurized component is present in the lubricating and cooling fluid in an amount that delivers about 1200 ppm to about 1300 ppm of sulfur, and the optional second sulfurized component is present in the lubricating and cooling fluid in an amount that delivers about 225 ppm to about 275 ppm of sulfur. In this embodiment, the first sulfurized component and the optional second sulfurized component can be present in the lubricating and cooling fluid in an amount that delivers about 1400 ppm to about 1500 ppm total sulfur.

[0061] Dispersant System: The lubricating and cooling fluids described herein include a dispersant system comprising at least two dispersants, such as oil-soluble ashless dispersants selected from the group consisting of succinimide dispersants, succinate dispersants, succinate-amide dispersants, Mannich base dispersants, polymeric polyamine dispersants, phosphatized versions thereof, and borated versions thereof. The dispersants can be capped with acidic molecules capable of reacting with secondary amino groups.

[0062] Hydrocarbyl dicarboxylic acids or anhydrides and polyalkylene polyamine reactions are used to make succinimide dispersants. Succinimide dispersants and their preparation are disclosed in U.S. Patent 7,897,696 and U.S. Patent 4,234,435, which are incorporated herein by reference. The hydrocarbyl portion of the hydrocarbyl dicarboxylic acid or anhydride can be derived from butene polymers, such as polymers of isobutylene. Suitable polyisobutylenes suitable for use herein include those formed from conventional polyisobutylenes or reactive high polyisobutylenes having a terminal vinylidene content of at least 60%, such as 70% to 90% and higher. Suitable polyisobutylenes can include those prepared using BF3catalysts.

[0063] The number average molecular weight of the polyisobutylene substituent of the dispersant can vary over a wide range, for example, from about 500 to about 5000, as measured by gel permeation chromatography (GPC) using polystyrene, which has a number average molecular weight of 180 to about 18,000, as a calibration reference. The GPC method provides, in addition, 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, which is also incorporated herein by reference.

[0064] The polyisobutylene portion in the dispersant preferably has a narrow molecular weight distribution (MWD), also known 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 about 1.5 to about 2.1, or about 1.6 to about 1.8.

[0065] The dicarboxylic acid or anhydride can be selected from carboxylic acid reactants such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethyl maleic anhydride, dimethyl maleic anhydride, ethyl maleic acid, dimethyl maleic acid, hexyl maleic acid, and the like, including the corresponding acid halides and C1-C4aliphatic esters. The molar ratio of the dicarboxylic acid or anhydride to the hydrocarbyl moiety in the reaction mixture used to make the hydrocarbyl-dicarboxylic acid or anhydride can vary widely. Thus, the molar ratio can vary from 5:1 to 1:5, for example, 3:1 to 1:3. A particularly suitable molar ratio of the acid or anhydride to the hydrocarbyl moiety is 1:1 to less than 1.6:1. Another useful molar ratio of the dicarboxylic acid or anhydride to the 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.

[0066] Any of a number of polyalkylene polyamines can be used as the dispersant additive. Non-limiting exemplary polyamines can include amino guanidine bicarbonate (AGBC), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and heavy polyamines. Heavy polyamines can comprise a mixture of polyalkylene polyamines having a small amount 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 a broader branching than conventional polyamine mixtures. Typically, these heavy polyamines have an average of 6.5 nitrogen atoms per molecule. Additional non-limiting polyamines useful in making hydrocarbyl-substituted succinimide dispersants are disclosed in U.S. Patent 6,548,458, the disclosure of which is incorporated herein by reference in its entirety. The molar ratio of hydrocarbyl-dicarboxylic acid or anhydride to polyalkylene polyamine can be from about 1 : 1 to about 3.0: 1.

[0067] In one embodiment, the dispersants in the present disclosure described herein can be the reaction product of a polyisobutenyl succinic anhydride (PIBSA) and a polyamine, such as a heavy polyamine. The dispersants herein can have a molar ratio of (A) polyisobutenyl-substituted succinic anhydride to (B) polyamine in the range of 4:3 to 1 : 10.

[0068] The Mannich base dispersants can be the reaction product of an alkyl phenol, typically having a long chain alkyl substituent on the ring, with one or more aliphatic aldehyde, especially formaldehyde and its derivatives, containing from about 1 to about 7 carbon atoms, and a polyamine, especially a polyalkylene polyamine. For example, Mannich base ashless dispersants can be formed by condensing about one mole proportion of a long chain hydrocarbon-substituted phenol having from about 1 mole to about 2.5 moles of formaldehyde and from about 0.5 moles to about 2 moles of a polyalkylene polyamine.

[0069] The dispersant system herein comprises at least two different dispersants. At least one of the dispersants described herein can be borated and / or phosphated, and preferably only the dispersants having longer chain polyisobutenyl moieties are borated and phosphated. These dispersants are typically the reaction product of i) at least one phosphorous compound and / or boron compound and ii) at least one ashless dispersant.

[0070] Suitable boron compounds useful in forming the dispersants herein include any boron compound or mixture of boron compounds capable of introducing boron-containing species into the ashless dispersant. Any organic or inorganic boron compound capable of such a reaction can be used. Thus, one can use boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF4, boric acids such as boronic acids (e.g., alkyl-B(OH)2or aryl-B(OH)2), boric acid (i.e., H3BO3), tetraboric acid (i.e., H2B5O7), metaboric acid (i.e., HBO2), ammonium salts of such boric acids, and esters of these boric acids. The use of complexes of boron trihalides with ethers, organic acids, inorganic acids, or hydrocarbons is a convenient method of introducing the boron reactant into the reaction mixture. Such complexes are known, for example, boron trifluoride-diethyl ether, boron trifluoride-phenol, boron trifluoride-phosphoric acid, boron trichloride-chloroacetic acid, boron tribromide-dioxane, and boron trifluoride-methylethyl ether.

[0071] Suitable phosphorus compounds for forming the dispersants herein include phosphorus compounds or mixtures of phosphorus compounds capable of introducing phosphorus-containing species into the ashless dispersant. Thus, one can use any organic or inorganic phosphorus compound capable of such a reaction. Thus, one can use these inorganic phosphorus compounds such as inorganic phosphoric acids and inorganic phosphorus oxides, including their hydrates. Typical organic phosphorus compounds include the peresters and partial esters of phosphoric acid such as the mono-, di-, and tri-esters of phosphoric acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid, and tetra- thiophosphoric acid; the mono-, di-, and tri-esters of phosphorous acid, thiophosphorous acid, dithiophosphorous acid, and trithiophosphorous acid; trihydrocarbyl phosphine oxides; trihydrocarbyl phosphine sulfides; mono- and dihydrocarbyl phosphonates (RPO(OR')(OR"), where R and R' are hydrocarbyl groups and R" is a hydrogen atom or a hydrocarbyl group), and their mono-, di-, and tri-thio analogs; mono- and dihydrocarbyl phosphinates (RP(OR')(OR"), where R and R' are hydrocarbyl groups and R" is a hydrogen atom or a hydrocarbyl group) and their mono- and di-thio analogs; and the like. Thus, one can use such compounds as phosphorous acid (H3PO3, sometimes described as H2(HPO3), sometimes referred to as orthophosphorous acid or phosphinic acid), phosphoric acid (H3PO4, sometimes referred to as orthophosphoric acid), hypophosphorous acid (H4P2O6), metaphosphoric acid (HPO3), pyrophosphoric acid (H4P2O7), hypophosphorous acid (H3PO2, sometimes referred to as hypophosphorous acid), pyrophosphorous acid (H4P2O5, sometimes referred to as pyrophosphinic acid), phosphinic acid (H3PO), tripolyphosphoric acid (H5P3O 10 ), tetrapolyphosphoric acid (H5P4O 13Phosphorus trioxide, phosphorus tetroxide, phosphorus pentoxide, etc. Partial or complete sulfur analogs, such as tetrathioacetic acid (H3PS4), thiophosphoric acid (H3PO3S), dithiophosphoric acid (H3PO2S2), trithiophosphoric acid (H3POS3), sesquisulfide, phosphorus heptasulfide, and phosphorus pentasulfide (P2S5, sometimes called P4S). 10 It can also be used to form the dispersant disclosed herein. Inorganic phosphorus halide compounds, such as PCl3, PBr3, POCl3, PSCl3, etc., can also be used.

[0072] Similarly, organophosphorus compounds such as monoesters, diesters, and trimers of phosphoric acid (e.g., trialkyl phosphates, dialkyl monoacid phosphates, monoalkyl diacid phosphates, and mixtures thereof), monoesters, diesters, and trimers of phosphorous acid (e.g., trialkyl phosphite, dialkyl hydrogen phosphite, alkyl diacid phosphite, and mixtures thereof), phosphonates (“primary” RP(O)(OR)2 and “secondary” R2P(O)(OR)), hypophosphonates, and phosphonyl halides (e.g., RP(O)Cl2 and R2P(O)Cl) can be used. Halogenated phosphites (e.g., (RO)PCl2 and (RO)2PCl), halogenated phosphates (e.g., ROP(O)Cl2 and (RO)2P(O)Cl), tertiary pyrophosphates (e.g., (RO)2P(O)—O—P(O)(OR)2), and all-sulfur or partially-sulfur analogs of any of the aforementioned organophosphorus compounds, wherein each hydrocarbon 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. Halogenated phosphine halides (e.g., alkyl tetrahalides, dialkyl trihalides, and trialkyl dihalides) and phosphine halides (monohalides and dihalides) may also be used.

[0073] As discussed above, the dispersant system for lubricating and cooling fluids described herein comprises at least two dispersants: (i) one obtained from polyisobutylene with a relatively high number-average molecular weight, and (ii) another obtained from polyisobutylene with a relatively low number-average molecular weight. The amounts of the two dispersants, as well as the provision of phosphorus and boron, are balanced relative to the dispersant dosage and the polyisobutylene portion of the dispersant to improve the conductivity of the lubricant and maintain suitable wear resistance and friction properties.

[0074] In one embodiment, the first dispersant for use in the dispersant system comprises a polyisobutenyl moiety having a number average molecular weight in the range of about 1500 to about 2500 and is present in the lubricating and cooling fluid in an amount sufficient to deliver greater than about 300 ppm of nitrogen, greater than about 400 ppm of nitrogen, about 300 ppm to about 700 ppm of nitrogen, about 450 ppm to about 500 ppm of nitrogen, or up to about 600 ppm or up to about 500 ppm of nitrogen (or other ranges therebetween).

[0075] The first dispersant can be borated and / or phosphated. Thus, in one embodiment, the first dispersant has a boron content of about 0.25 wt% to about 0.5 wt%, a phosphorus content of about 0.5 wt% to about 1 wt%, and a nitrogen content of about 1.5 wt% to about 2 wt%. In another embodiment, the first dispersant has a boron content of about 0.3 wt% to about 0.4 wt%, a phosphorus content of about 0.65 wt% to about 0.8 wt% phosphorus, and a nitrogen content of about 1.7 wt% to about 1.8 wt% nitrogen. In some cases, the first dispersant is borated and phosphated and has a weight ratio of boron plus phosphorus to nitrogen ((B+P) / N) of 0:1 to about 0.8:1, or about 0.6:1 to about 0.7:1, or about 0.6:1 to about 0.60:1 to about 0.65:1.

[0076] In one embodiment, the first dispersant of the dispersant system is borated and phosphated and is present in the lubricating and cooling fluid in an amount sufficient to deliver less than about 125 ppm of boron, less than about 300 ppm of phosphorus, less than about 500 ppm of nitrogen, or less than about 700 ppm. In another embodiment, the first dispersant is borated and phosphated and is present in the lubricating and cooling fluid in an amount sufficient to deliver less than about 100 ppm of boron, less than about 250 ppm of phosphorus, and less than about 700 ppm of nitrogen. In another embodiment, the first dispersant is borated and phosphated and is present in the lubricating and cooling fluid in an amount sufficient to deliver about 80 ppm to about 100 ppm of boron, about 200 ppm to about 250 ppm of phosphorus, and about 450 ppm to about 700 ppm of nitrogen, or any other range of such elements between the amounts described herein.

[0077] The second dispersant for use in the dispersant system includes a polyisobutenyl moiety having a number average molecular weight of less than about 1000, or from about 500 to about 1000, and is present in the lubricating and cooling fluid in an amount sufficient to deliver less than about 150 ppm of nitrogen, or less than about 130 ppm of nitrogen, less than about 115 ppm of nitrogen, less than 110 ppm of nitrogen, less than about 100 ppm of nitrogen, or less than 50 ppm of nitrogen. In other approaches, the second dispersant includes greater than about 10 ppm of nitrogen, greater than about 20 ppm of nitrogen, greater than 30 ppm of nitrogen, greater than about 50 ppm of nitrogen, or greater than about 80 ppm of nitrogen (or any other range of such amounts herein). In embodiments herein, the second dispersant is preferably not boronated and / or phosphonated and does not provide such elements to the fluid.

[0078] As shown in the examples herein, when a first dispersant having a relatively high molecular weight is present in the lubricating and cooling fluid in an amount to deliver less than about 125 ppm of boron, less than about 300 ppm of phosphorus, and less than about 700 ppm of nitrogen (or other ranges described above) and is combined with a second dispersant in the lubricating and cooling fluid in an amount to deliver less than about 150 ppm of nitrogen (or other ranges described above) and no boron or phosphorus, the resulting composition has reduced conductivity and maintains suitable wear and friction performance. If a single dispersant having a relatively low molecular weight is used to deliver boron and / or phosphorus to the lubricating and cooling fluid, the resulting composition has increased conductivity.

[0079] In yet other approaches or embodiments, the combined dispersant system of the fluids herein is balanced to provide a high level of boron and phosphorus relative to the total molecular weight of the combined polyisobutenyl moieties within the dispersant system. For example, when at least one of the first dispersant and the second dispersant is boronated and phosphonated such that the total amount of boron and phosphorus in the dispersant system is from about 0.5 to about 0.7 relative to the nitrogen in the dispersant system and wherein the first dispersant and the second dispersant deliver a total of at most about 100 ppm of boron and phosphorus per 1000 number average molecular weight of the combined polyisobutenyl moieties for use in the dispersant system, a surprisingly good conductivity is obtained.

[0080] Such unique dispersant system combinations surprisingly achieve low conductivity along with other desirable fluid performance characteristics. As further explained in the examples below, Figure 1 The significant impact of such dispersant system combinations on the conductivity of the fluids herein is shown.

[0081] Friction modifier system: The lubricating and cooling fluids described herein also contain a friction modifier system that includes specific amounts of at least two friction modifiers, such as an alkoxylated aliphatic amine and an ether amine, to provide suitable friction performance and reduced conductivity.

[0082] Alkoxylated fatty amines useful in the present application include, but are not limited to, bis[2-hydroxyethyl]cocoamine, polyoxyethylene cocoamine, (bis[2- hydroxyethyl]soyamine, bis[2-hydroxyethyl]tallowamine, polyoxyethylene tallowamine, bis[2- hydroxyethyl]oleylamine, bis[2-hydroxyethyl]stearylamine, and polyoxyethylene stearylamine. In one embodiment, the alkoxylated fatty amine is a di(hydroxyalkyl) fatty tertiary amine, wherein the same or different hydroxyalkyl groups each contain from 2 to about 4 carbon atoms, and wherein the fatty group is an acyclic hydrocarbon group containing from about 16 to about 25 carbon atoms. The alkoxylated fatty amine can be present in the lubricating and cooling fluids in an amount sufficient to deliver up to about 20 ppm of nitrogen or up to about 15 ppm of nitrogen.

[0083] Ether amines useful in the present application include primary ether amines and ether diamines. More specifically, these can include, but are not limited to, one or more of isohexyloxypropylamine, 2- ethylhexyloxypropylamine, octyl / decyloxypropylamine, isodecyloxypropylamine, isododecyloxypropylamine, isotridecyloxypropylamine, C 12-15 Ether amines useful in the present application include primary ether amines and ether diamines. More specifically, these can include, but are not limited to, one or more of isohexyloxypropylamine, 2- ethylhexyloxypropylamine, octyl / decyloxypropylamine, isodecyloxypropylamine, isododecyloxypropylamine, isotridecyloxypropylamine, C

[0084] In one embodiment, the alkoxylated fatty amine and ether amine can be present in the lubricating and cooling fluids in an amount sufficient to deliver up to about 40 ppm of nitrogen or up to about 30 ppm of nitrogen. In another embodiment, the alkoxylated fatty amine is a di(hydroxyalkyl) fatty tertiary amine and the ether amine is isodecyl oxypropylamine, and the combination of the two amines is present in an amount sufficient to deliver up to about 40 ppm of nitrogen or up to about 30 ppm of nitrogen.

[0085] In another embodiment, the lubricating and cooling fluids described herein further comprise an optional third friction modifier, such as a fatty diamine. Examples of suitable fatty diamines are mono- or di-alkyl, symmetric or asymmetric ethylenediamine, propylenediamine (1,2 or 1,3) and polyamine analogs of the above, n-coco-1,3-diaminopropane, n-soy-1,3-diaminopropane, n-tallow-1,3-diaminopropane, and n-oleyl-1,3-diaminopropane. The fatty diamine can be present in the lubricating and cooling fluids in an amount sufficient to deliver up to about 5 ppm of nitrogen or up to about 3 ppm of nitrogen.

[0086] In one embodiment, the lubricating and cooling fluids described herein include alkoxylated aliphatic amines, ether amines, and fatty diamines, and combinations of these components can be present in the lubricating and cooling fluids in amounts sufficient to deliver up to about 30 ppm of nitrogen. In another embodiment, the lubricating and cooling fluids include di(hydroxyalkyl) aliphatic tertiary amines, isodecyloxypropylamine, n-oleyl-1,3-diaminopropane, and combinations of these compounds present in amounts sufficient to deliver up to about 30 ppm of nitrogen.

[0087] Other additives

[0088] In addition to the components described above, the lubricating and cooling fluids described herein can also include other additives typical of transmission fluid composition types. Such additives include, but are not limited to, antioxidants, viscosity modifiers, phosphorus-containing components, detergents, corrosion inhibitors, rust-preventive additives, antifoams, demulsifiers, pour point depressants, seal swell agents, and additional dispersants, additional friction modifiers, and additional sulfur-containing components.

[0089] Antioxidants: In some embodiments, the lubricating and cooling fluids include one or more antioxidants. Suitable antioxidants include phenolic antioxidants, aromatic amine antioxidants, sulfur-containing antioxidants, and organic phosphites, among others.

[0090] Examples of phenolic antioxidants include 2,6-di-tert-butylphenol, a liquid mixture of tert-butylated phenols, 2,6-di-tert-butyl-4-methylphenol, 4,4'-methylenebis(2,6-di-tert- butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), and mixed methylene-bridged polyalkylphenols, as well as 4,4'-thiobis(2-methyl-6-tert-butylphenol), N,N'- di-sec-butyl-p-phenylenediamine,

[0091] 4-isopropylaminodiphenylamine, phenyl-a-naphthylamine, phenyl-a-naphthylamine, and cycloalkylated diphenylamine. Examples include hindered tertiary butylated phenols, bisphenols, and cinnamic acid derivatives, and combinations thereof.

[0092] Aromatic amine antioxidants include, but are not limited to, diaryl amines having the following formula:

[0093]

[0094] wherein R' and R" each independently represent a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. Examples of substituents of the aryl group include aliphatic hydrocarbon groups such as alkyl groups having 1 to 30 carbon atoms, hydroxyl groups, halogen groups, carboxylic acid or ester groups, or nitro groups.

[0095] The aryl groups are preferably substituted or unsubstituted phenyl or naphthyl groups, in particular wherein one or both of the aryl groups are substituted with at least one alkyl group having 4 to 30 carbon atoms, preferably 4 to 18 carbon atoms, most preferably 4 to 9 carbon atoms. Preferably one or both of the aryl groups are substituted, for example monoalkylated diphenylamine, dialkylated diphenylamine or a mixture of monoalkylated diphenylamine and dialkylated diphenylamine.

[0096] Examples of diaryl amines that can be used include, but are not limited to, diphenylamine; various alkylated diphenylamines, 3-hydroxydiphenylamine, N-phenyl-1,2- phenylenediamine, N-phenyl-1,4-phenylenediamine, monobutyldiphenylamine, dibutyldiphenylamine, monooctyldiphenylamine, dioctyldiphenylamine, monononyldiphenylamine, dinonyldiphenylamine, monotetradecyldiphenylamine, dotetradecyldiphenylamine, phenyl-a-naphthylamine, monooctylphenyl-a-naphthylamine, phenyl-β-naphthylamine, monoheptyldiphenylamine, diheptyldiphenylamine, p- orientated styrenated diphenylamine, mixed butyloctyl diphenylamine, and mixed octylstyryldiphenylamine.

[0097] Sulfur-containing antioxidants include, but are not limited to, sulfurized olefins 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 having an average molecular weight of 168 to 351 g / mole) are preferred. Examples of olefins that can be used include a-olefins, isomerized a-olefins, branched olefins, cyclic olefins, and combinations of these.

[0098] a-olefins include, but are not limited to, any C4 to C25 a-olefin. The a-olefins can be isomerized prior to or during the sulfurization reaction. Structural and / or conformational isomers of a-olefins containing internal double bonds and / or branches can also be used. For example, isobutylene is the branched olefin counterpart of a-olefin 1-butene.

[0099] Sulfur sources that can be used in the sulfurization of olefins include elemental sulfur, sulfur monochloride, sulfur dichloride, sodium sulfide, sodium polysulfide, and mixtures thereof, added together or at different stages of the sulfurization process.

[0100] Unsaturated oils, due to their unsaturation, can also be sulfurized and used as antioxidants. Examples of oils or fats that can be used include corn oil, canola oil, cottonseed oil, grape seed oil, olive oil, palm oil, peanut oil, coconut oil, rapeseed oil, safflower oil, sesame oil, soybean oil, sunflower seed oil, tallow, and combinations of these.

[0101] The total amount of antioxidant in the lubricating and cooling fluids described herein can be present in an amount that delivers up to about 200 ppm of nitrogen or up to about 100 ppm of nitrogen or up to about 150 ppm of nitrogen or about 100 ppm to about 150 ppm of nitrogen.

[0102] Additional friction modifiers: In some embodiments, the lubricating and cooling fluid includes additional friction modifiers other than those included in the above-described friction modifier systems. Suitable additional friction modifiers can include metal-containing and non-metal-containing friction modifiers, and can 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, aminoguanidines, alkenyl amides, phosphonates, metal-containing compounds, glycerol esters, sulfurized fatty compounds and olefins, sunflower oil, other naturally occurring vegetable or animal oils, dicarboxylic acid esters, esters or partial esters of polyols with one or more aliphatic or aromatic carboxylic acids, and the like.

[0103] Suitable friction modifiers can contain a hydrocarbyl group selected from linear, branched, or aromatic hydrocarbyl groups or mixtures thereof, and such hydrocarbyl groups can be saturated or unsaturated. The hydrocarbyl groups can be composed of carbon and hydrogen or heteroatoms such as sulfur or oxygen. The hydrocarbyl groups can range from 12 to 25 carbon atoms. In some embodiments, the friction modifier can be a long chain fatty acid ester. In another embodiment, the long chain fatty acid ester can be a mono- or di-ester or (tri)glyceride. The friction modifier can be a long chain fatty amide, long chain fatty ester, long chain fatty epoxide derivative, or long chain imidazoline.

[0104] Other suitable friction modifiers can include organic, ashless (non-metal containing), non-nitrogen-containing organic friction modifiers. Such friction modifiers can include esters formed by reacting carboxylic acids and anhydrides with alkanols, and generally contain a polar end group (e.g., carboxyl or hydroxyl) covalently bonded to a lipophilic hydrocarbon chain. An example of an organic ashless non-nitrogen friction modifier is generally known as glycerol monooleate (GMO), which can contain mono-, di-, and tri-esters of oleic acid. Other suitable friction modifiers are described in U.S. Patent No. 6,723,685.

[0105] Amine-based friction modifiers can include amines or polyamines. Such compounds can have linear, saturated or unsaturated hydrocarbyl groups or mixtures thereof, and can contain 12 to 25 carbon atoms. Other examples of suitable friction modifiers include alkoxylated amines and alkoxylated ether amines. Such compounds can have linear, saturated or unsaturated hydrocarbyl groups or mixtures thereof. They can contain about 12 to about 25 carbon atoms. Examples include ethoxylated amines and ethoxylated ether amines.

[0106] Amines and amides can be used as such or in the form of adducts or reaction products with boron compounds such as boron oxides, boron halides, metaborates, boric acids or boric acid mono-, di- or tri-alkyl esters. Other suitable friction modifiers are described in U.S. Patent No. 6,300,291.

[0107] If the additional friction modifier contains nitrogen, such additional friction modifier can be present in the lubricating and cooling fluid in an amount to deliver up to about 200 ppm of nitrogen, or up to about 150 ppm of nitrogen, or from about 100 ppm to about 150 ppm of nitrogen.

[0108] Detergents: Metal detergents that can be included in the lubricating and cooling fluids described herein can generally include a polar head with a long hydrophobic tail, where the polar head includes a metal salt of an acidic organic compound. The salts can contain substantially stoichiometric amounts of metal, in which case they are generally described as normal or neutral salts, and typically have a total base number or TBN (as measured by ASTM D2896) of 0 to less than 150. Large amounts of metal bases can 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 detergents include micelles of neutralized detergent around a core of inorganic metal base (e.g., a hydrated carbonate). Such overbased detergents can have a TBN of 150 or more, such as from 150 to 450 or more.

[0109] Detergents: Metal detergents that can be included in the lubricating and cooling fluids described herein can generally include a polar head with a long hydrophobic tail, where the polar head includes a metal salt of an acidic organic compound. The salts can contain substantially stoichiometric amounts of metal, in which case they are generally described as normal or neutral salts, and typically have a total base number or TBN (as measured by ASTM D2896) of 0 to less than 150. Large amounts of metal bases can 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 detergents include micelles of neutralized detergent around a core of inorganic metal base (e.g., a hydrated carbonate). Such overbased detergents can have a TBN of 150 or more, such as from 150 to 450 or more.

[0110] Metal-containing detergents can be present in the lubricating and cooling fluids in an amount sufficient to improve the rust-preventive properties of the fluid. The metal-containing detergents can be present in the fluid in an amount sufficient to provide up to 300 ppm of alkali and / or alkaline earth metals, based on the total weight of the lubricating and cooling fluid. In one example, the metal-containing detergents can be present in an amount sufficient to provide from about 100 ppm to about 300 ppm of alkali and / or alkaline earth metals. In another embodiment, the metal-containing detergents can be present in an amount sufficient to provide from about 220 ppm to about 250 ppm of alkali and / or alkaline earth metals.

[0111] Corrosion inhibitors: Rust inhibitors or corrosion inhibitors can also be included in the lubricating compositions described herein. Such materials include mono- and poly-carboxylic acids. Examples of suitable mono-carboxylic acids are octanoic acid, decanoic acid, and dodecanoic acid. Suitable poly-carboxylic acids include di- and tri-mer acids, such as produced from acids like tall oil fatty acid, oleic acid, linoleic acid, or the like.

[0112] Another useful type of rust inhibitor can be an alkenyl succinic acid and alkenyl succinic anhydride corrosion inhibitor, such as, for example, tetrapropenyl succinic acid, tetrapropenyl succinic anhydride, tetradecenyl succinic acid, tetradecenyl succinic anhydride, hexadecenyl succinic acid, hexadecenyl succinic anhydride, and the like. Also useful are half esters of alkenyl succinic acids having from 8 to 24 carbon atoms in the alkenyl group with alcohols such as polyethylene glycol. Other suitable rust or corrosion inhibitors include ether amines, acid phosphates, amines, polyethoxylated compounds such as ethoxylated amines, ethoxylated phenols, and ethoxylated alcohols, imidazolines, amino succinic acids or derivatives thereof, and the like. Mixtures of such rust or corrosion inhibitors can be used. The total amount of corrosion inhibitor, when present in the lubricating composition described herein, can range from 0.01 wt % to 1.0 wt %, or up to 2.0 wt %, based on the total weight of the lubricating composition.

[0113] Viscosity modifier: The lubricating and cooling fluid can optionally contain one or more viscosity modifiers. Suitable viscosity modifiers can include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutylenes, hydrogenated styrene-isoprene polymers, styrene / maleate copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkylstyrenes, hydrogenated alkenyl aromatic conjugated diene copolymers, or mixtures thereof. The viscosity modifier can include a star polymer, and suitable examples are described in U.S. Pub. No. 2012 / 0101017 Al.

[0114] In addition to or in place of viscosity modifiers, the lubricating and cooling fluids described herein can also optionally contain one or more dispersant viscosity modifiers. Suitable dispersant viscosity modifiers can 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.

[0115] The total amount of viscosity modifier and / or dispersant viscosity modifier, when present, can 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.

[0116] Demulsifiers: Demulsifiers include trialkyl phosphates, as well as various polymers and copolymers of ethylene glycol, oxirane, propylene oxide, or mixtures thereof, including poly(ethylene oxide), poly(propylene oxide), and (ethylene oxide-propylene oxide) polymers. When present, the amount of demulsifier in the lubricating and cooling fluid can be up to about 0.05 wt %, or up to about 0.02 wt %, or less than about 0.015 wt %, based on the total weight of the lubricating and cooling fluid.

[0117] Antifoam agents: Antifoam agents for reducing or preventing the formation of stable foam include silicones, polyacrylates, or organic polymers. Foam inhibitors that can be used in the disclosed compositions include polysiloxanes, copolymers of ethyl acrylate and 2-ethylhexyl acrylate, and optionally vinyl acetate. When present, the amount of antifoam agent in the lubricating and cooling fluid can be up to about 0.1 wt.%, or up to about 0.08 wt.%, or less than about 0.07 wt.%, based on the total weight of the lubricating and cooling fluid.

[0118] Pour point depressants: The lubricating and cooling fluid can optionally contain one or more pour point depressants. Suitable pour point depressants can include esters of maleic anhydride-styrene, polymethacrylates, polymethyl methacrylate, polyacrylates, or polyacrylamides, or mixtures thereof. When present, the pour point depressants can be present in an amount of 0.001 wt.% to about 0.04 wt.%, based on the total weight of the lubricating and cooling fluid.

[0119] In general, the lubricating and cooling fluids described herein can include additive components in the ranges listed in Table 2.

[0120] Table 2

[0121] Components wt% (suitable embodiments) wt% (preferred embodiments) Dispersant system 3.0-8.0 5.0-7.0 Sulphur component 0.05-1.5 0.5-1.0 Friction modifier component 0.3-0.7 0.4-0.6 Detergent 0.05-0.5 0.1-0.3 Antioxidant 0.1-0.6 0.3-0.5 Defoamer 0-0.05 0.1-0.04 Viscosity index improver 0-7.0 0-5.0 Base oil Balance Balance Total 100 100

[0122] The percentages of the above components represent the weight percent of each component based on the total weight of the lubricating and cooling fluid containing the component. The additives used to formulate the compositions described herein can be blended into the base oil individually or in various subcombinations. However, it can be suitable to blend all components simultaneously using an additive concentrate (i.e., additives plus diluent, such as a hydrocarbon solvent). The use of an additive concentrate takes advantage of the mutual compatibility provided by the combination of ingredients when in the form of an additive concentrate. In addition, the use of a concentrate reduces the blending time and reduces the potential for blending errors.

[0123] Motor systems that include a single fluid that provides not only lubrication to gears, clutches, and other mechanical components but also cooling to electric motors should provide good wear and friction performance, low copper corrosion, and relatively low electrical conductivity. However, the high temperatures of electric motors present challenges to developing this type of fluid. In the sump of an electric motor, the lubricating and cooling fluid can reach temperatures of greater than about 70 °C or greater than about 100 °C, and in some cases, temperatures of about 70 °C to about 125 °C. Likewise, the temperature of the copper windings in the stator of an electric motor can reach at least about 150 °C, and in some cases, up to 180 °C. Additives provide elements such as sulfur, boron, or phosphorus to achieve good wear performance, but can result in excessive copper corrosion and higher electrical conductivity. Moreover, these negative effects are exacerbated at higher temperatures. Thus, it is unexpected that the combination of selected additives in amounts of sulfur, phosphorus, and boron provided herein provide acceptable wear and friction performance while also providing low copper corrosion and low electrical conductivity at elevated temperatures.

[0124] In any embodiment herein, a fluid comprising a sulfurized component, a dispersant system, and a friction modifier system as described herein and when used with an oil of lubricating viscosity, including an API Group III base oil, an API Group IV base oil, or a mixture thereof, can exhibit one or more of the following: (i) a torque when using a clutch bench test, applying a maximum force of about 2 kN and at a fluid temperature of about 80 °C, as measured at 10% of maximum RPM, 50% of maximum RPM, and 90% of maximum RPM in 3000 shifts; (ii) a torque when using a clutch bench test, applying a maximum force of about 2 kN and at a fluid temperature of about 80 °C, as measured after dynamic shifts in 3000 shifts and after start-up in 3000 shifts; (iii) a mu V behavior demonstrating controllable shift performance when using a clutch bench test, applying a maximum force of about 2 kN, a fluid temperature of about 80 °C, and a ramp speed n of 100 to 0, wherein the mu V behavior exhibits a positive shape feature from 100 RPM to 0 RPM; (iv) a synchronous friction value when using a SSP180 synchronous test stand (ZF Friedrichshafen AG), wherein the maximum force is about 0.6 kN, the fluid temperature is about 80 °C, and the double carbon synchronous ring is at 1450 rpm for up to 100 shifts, an average coefficient of friction (mu avg ) of about 0.1 for up to 100 shifts, and a minimum coefficient of friction (mu min) is about 0.88; (v) an electrical resistance of at least about 10 M* m at a temperature range of about 25 °C to about 120 °C, and in particular about 40 °C to about 80 °C, and at least 15 M* m at 100 °C, about 30 M* m at 80 °C, and about 115 M* m at 40 °C, according to DIN EN 60247 using Flucon or equivalent conductivity meter at a frequency of 60 hz; and / or (vi) a dissipation factor (tan delta) of about 10 or less from about 30 °C to about 100 °C, and in particular from about 80 °C to about 100 °C, according to DIN EN 60247 using Flucon or equivalent conductivity meter at a frequency of 60 hz.

[0125] Example

[0126] The following non-limiting examples illustrate features and advantages of one or more embodiments of the present disclosure. In these examples, and elsewhere in this application, all ratios, parts, and percentages are by weight unless otherwise indicated. To demonstrate how the vulcanization components, dispersant systems, and friction modifier systems affect wear, oxidation, copper compatibility, and electrical conductivity of the fluids, exemplary finished fluids were formulated and tested.

[0127] Example 1

[0128] The formulations were evaluated in the FZG scuffing test, DKA oxidation test, copper corrosion test, and the initial electrical conductivity was measured.

[0129] The FZG scuffing test is a wear test used to evaluate the load carrying capacity of lubricants and was performed according to ASTM D5182-97 (2014). The results are reported in load stage passes and better results are obtained for samples with higher load stage passes.

[0130] The DKA oxidation test was performed according to CEC L-48-A-00 with operating conditions of 170 °C or 180 °C for 192 hours. The result obtained is the percent increase in kinematic viscosity at 100 °C. Lower values indicate improved performance.

[0131] It is beneficial for electric motor fluids to exhibit low electrical conductivity, thus acting as an insulator to some extent. The electrical conductivity of the fluids was measured according to a modified version of ASTM D2624-15 (using Flucon Epsilon+ to test lubricants at 1.5 V instead of fuels).

[0132] ​The copper corrosion test is a modified version of ASTM D130-18 in which copper strips are immersed in the lubricant at 150°C for 504 hours. At the end of the test, the copper content of the oil is evaluated. A higher copper content in the oil indicates that the lubricant is corrosive to copper.

[0133] The thermal conductivities of the formulations were also tested to ensure that they exhibit proper cooling ability. The thermal conductivity of each formulation was measured at 100°C according to ASTM D7896-14 using a single measurement, and all formulations exhibited a thermal conductivity between 126 mW / (m-K) and 136 mW / (m-K), and thus had suitable cooling ability.

[0134] The formulations tested in Table 3 below all contain the same additive base package, which additive base includes an antioxidant, a friction modifier, a defoamer, and a demulsifier. The formulations also contain different amounts of a sulfurizing component, an additional friction modifier, a dispersant, and a base oil, as shown in Table 3. The formulations were tested in a wide range of base oils to obtain a finished fluid with a kinematic viscosity at 100°C between 4.10 cSt and 4.33 cSt. The formulations of the present invention contain similar additives to the comparative formulations, but balance the delivery of sulfur, friction modifier, and dispersant in different ways to achieve surprisingly improved wear, oxidation stability, copper compatibility, and low electrical conductivity, even with high levels of sulfur, boron, and phosphorus that are not expected to perform as well in lubricants for electric motor systems. Details of these components are described below:

[0135] Sulphur component S-1 Zinc Omadine®: 2,5-dimercapto-1,3,4-thiadiazole and its hydrocarbyl-substituted derivatives containing approximately 35 wt% sulfur, which are 75:25 to 85:15 mixtures of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole.

[0136] Sulphur component S-2 Zinc Omadine®: 2,5-dimercapto-1,3,4-thiadiazole and its hydrocarbyl-substituted derivatives containing approximately 35 wt% sulfur, which are 75:25 to 85:15 mixtures of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole.

[0137] Friction modifier FM-1 Zinc Omadine®: 2,5-dimercapto-1,3,4-thiadiazole and its hydrocarbyl-substituted derivatives containing approximately 35 wt% sulfur, which are 75:25 to 85:15 mixtures of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole.

[0138] Friction modifier FM-2 Zinc Omadine®: 2,5-dimercapto-1,3,4-thiadiazole and its hydrocarbyl-substituted derivatives containing approximately 35 wt% sulfur, which are 75:25 to 85:15 mixtures of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole.

[0139] Friction modifier FM-3 Zinc Omadine®: 2,5-dimercapto-1,3,4-thiadiazole and its hydrocarbyl-substituted derivatives containing approximately 35 wt% sulfur, which are 75:25 to 85:15 mixtures of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole. Zinc Omadine®: 2,5-dimercapto-1,3,4-thiadiazole and its hydrocarbyl-substituted derivatives containing approximately 35 wt% sulfur, which are 75:25 to 85:15 mixtures of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole.

[0140] Dispersant D-1 : Phosphonated and boronated succinimide dispersant made from 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. The dispersant has about 0.76 wt% phosphorus, about 0.35 wt% boron, and about 1.75 wt% nitrogen.

[0141] Dispersant D-2 : Phosphonated and boronated succinimide dispersant obtained from 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 has about 0.77 wt% nitrogen, 0.15 wt% boron, and 0.35 wt% phosphorus.

[0142] 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 about 2.1 wt% nitrogen.

[0143] Base oil : Group IV base oils include a mixture of polyalphaolefin (PAO) base oils having a kV100 of about 2 cSt and about 4 cSt oil to achieve the finished fluid viscosity target. Group III base oils include a mixture of oils having about 3 cSt and about 4 cSt oil to achieve the finished fluid viscosity target.

[0144] All of the inventive formulations contain a first sulfurized component, in this case 2,5-dimercapto-1,3,4-thiadiazole and its hydrocarbyl substituted derivatives, at a treat rate to deliver between 1000 ppm and 1500 ppm of sulfur to the lubricant. Two of the inventive formulations also contain an optional second sulfurized component, in this case sulfurized synthetic whale oil, in an amount up to 300 ppm sulfur relative to the lubricant. All of the inventive examples exhibit improved wear performance and improved copper protection compared to comparative examples that deliver too little or too much sulfur from the first sulfurized component and / or too much sulfur from the second sulfurized component.

[0145] In the inventive and comparative formulations, the friction modifier system comprises the following friction modifiers: an alkoxylated aliphatic amine, an ether amine, and a fatty diamine. The inventive formulations contain these components in amounts to provide suitable friction performance and reduced electrical conductivity.

[0146] In the comparative formulation, the dispersant system comprises one phosphonated and boronated succinimide dispersant obtained from 950 MW polyisobutylene. In the inventive sample, the dispersant system comprises two dispersants. The first dispersant is a phosphonated and boronated succinimide dispersant obtained from 2300 Mn polyisobutylene. The second dispersant is a succinimide dispersant obtained from 950 Mn polyisobutylene. Without being bound by any particular theory, it is believed that the inclusion of the first dispersant and the second dispersant in the inventive formulation improves the electrical conductivity of the lubricant while maintaining suitable wear and friction properties. The surprising effect of the dispersant system is shown in Tables 4 and 5 and Figure 1

[0147] Table 3: Fluid composition

[0148]

[0149]

[0150] Figure 1 The improvement of the inventive sample over the comparative sample is shown in how the ratio of boron and phosphorus in the dispersant system is provided relative to the number average molecular weight of the total polyisobutylene portion of one or more of the dispersant system. Surprisingly, this factor exhibits an effect on electrical conductivity, with the inventive sample showing a much lower electrical conductivity suitable for use in an electric motor system.

[0151] Table 4: Calculated fluid elemental analysis

[0152]

[0153] *Inv 1 has a 3.25 Mn of combined polyisobutylene used to obtain the dispersants in the dispersant system per 1000 molecular weight calculated from 2300 Mn PIB of dispersant 2 plus 950 Mn PIB of dispersant 3 divided by 1000 or (2300 + 950) / 1000. (Other examples are calculated in the same manner.)

[0154] **Inv 1 has a ratio of 92.3 calculated by adding 90 ppm of boron and 210 ppm of phosphorus divided by 3.25 Mn of combined polyisobutylene used to obtain the dispersants in the dispersant system per 1000 molecular weight or (210 + 90) / 3.25. (Other examples are calculated in the same manner.)

[0155] Table 5: Fluid performance

[0156]

[0157] Example 2 :​

[0158] The torque of the inventive fluid of Example 1 comprising a sulfidic component, a dispersant system and a friction modifier system was further evaluated using a clutch bench test applying a maximum force of 2 kN and a fluid temperature of 80 °C together with an oil having a lubricating viscosity comprising an API Group III base oil, an API Group IV base oil or a mixture thereof. As shown in Figure 2 , Figure 3 and Figure 4 Torque was measured in N*m at 10% of the maximum RPM, 50% of the maximum RPM and 90% of the maximum RPM, respectively, out of 3000 shifts. If the torque measurement deviates significantly from the illustrated values, a poor shift quality can occur.

[0159] Example 3

[0160] The torque of the inventive fluid from Example 2 after dynamic shifts and after take-off was further evaluated using the clutch bench test of Example 2 applying a maximum force of 2 kN and a fluid temperature of 80 °C. Figure 5 Torque measurements after dynamic shifts out of 3000 shifts are shown. Figure 6 Torque measurements after take-off out of 3000 shifts are shown. If the torque values deviate significantly from the illustrated values, a poor shift quality can occur and the torque transmission can not be optimal.

[0161] Example 4

[0162] The controllable shift behavior (Torque-V behavior) of the inventive fluid from Example 2 was further evaluated using the clutch bench test of Example 2 applying a maximum force of 2 kN, a fluid temperature of 80 °C and a ramp speed n from 100 to 0. In Figure 7 Torque-V measurements are plotted on 1 / min [X] and have a positive shape feature from 100 RPM to 0 RPM. If the Torque-V measurements deviate from the plotted values, a poor shift quality with noise and vibrations can occur.

[0163] Example 5

[0164] The synchronization friction values of the inventive fluid from Example 2 were further evaluated using the SSP180 synchronous test bench (ZF Friedrichshafen AG) applying a maximum force of 600 N, a fluid temperature of 80 °C, double carbon synchronization rings and at 1450 rpm. As shown in Figure 8 For up to 100 shifts, the fluid showed an average friction coefficient (μ avg ) of about 0.1. Figure 9indicating that the fluid exhibited a minimum coefficient of friction (μ min ) of about 0.88 for up to 100 shifts.

[0165] Example 6

[0166] The specific resistance of the inventive fluid from Example 2 was further evaluated using a Flucon conductivity meter at a frequency of 60 hz according to DIN EN 60247. As shown in Table 2, the specific resistance of the fresh and used inventive fluid was at least 10 M* m over a temperature range of 25 °C to 120 °C. The specific resistance of the fresh and used inventive fluid was at least 15 M* m at 100 °C. For global unified light-duty vehicle test (WLTP) laboratory testing, the oil temperature is about 40 °C, and for normal consumer driving schedules, the oil temperature is about 80 °C. As shown in Table 2, the inventive fluid (fresh and used) had a specific resistance of about 115 M* m at 40 °C and about 30 M* m at 80 °C, which is much higher than the fresh or used comparative ATF and DCT gear oil shown in Table 1. Figure 10 Figure 10 Figure 10

[0167] Example 7

[0168] The dissipation factor (tan d) of the inventive fluid from Example 2 was further evaluated using a Flucon conductivity meter at a frequency of 60 hz according to DIN EN 60247. As shown in Table 3, the dissipation factor (tan d) was 10 or less from 30 °C to 100 °C. For normal consumer driving schedules with a temperature of 80 °C to 100 °C, the dissipation factor of the inventive fluid (fresh and used) was 10 or less, but the fresh and used comparative ATF and DCT gear oil were both higher than 10 at temperatures higher than 80 °C. Figure 11

[0169] It is to be understood that while the present disclosure has been described in conjunction with the detailed description thereof and the foregoing outline, the foregoing description is meant to illustrate and not to limit the scope of the disclosure. Other aspects, advantages and modifications will occur to those skilled in the art to which the disclosure pertains. The true scope of the present disclosure is defined by the appended claims.

[0170] ​​​​Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. As used in the entire specification and claims, "a" and / or "an" can refer to one or more than one. Unless otherwise indicated, all numbers expressing quantities of components, characteristics, amounts, and so forth as used in the specification and claims are to be understood as being modified in all instances by the term "about," regardless of whether the term "about" itself appears in the specification and claims. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations. 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 indication is presented solely in terms of its capability to indicate a set of possible values in the various formulations. Although 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.

[0171] It should be understood that every component, compound, substituent, or parameter disclosed herein is to be interpreted as being disclosed in combination with one or more of every other component, compound, substituent, or parameter disclosed herein, either individually or in combination with every other component, compound, substituent, or parameter disclosed herein.

[0172] It should further be understood that every range of values disclosed herein is to be interpreted as having been disclosed to encompass every specific value within the range, to the same extent as such specific value is explicitly, numerically, listed in this specification.

[0173] It should further be understood that every lower limit of each range of values disclosed herein is to be interpreted as having been disclosed in combination with every upper limit of each range of values disclosed herein and with every specific value within each range of values disclosed herein, to the same extent as such lower limit is explicitly, numerically, listed in this specification. The disclosure is thus to be interpreted to encompass the disclosure of all ranges derived by combining each lower limit with each upper limit or with each specific value within each range, or by combining each upper limit with each specific value within each range.

[0174] Further, a specific amount / value of a component, compound, substituent, or parameter disclosed in the specification or in an example is to be interpreted as a disclosure of a lower limit or an upper limit of a range, and thus can be combined with any other lower limit or upper limit or specific amount / value of a range of the same component, compound, substituent, or parameter disclosed elsewhere in the disclosure to form a range of that component, compound, substituent, or parameter.

Claims

1. A method for lubricating gears and clutches in an electric motor system and simultaneously cooling an electric machine therein, the method comprising: operating an electric motor system containing a lubricating and cooling fluid such that the temperature of the lubricating and cooling fluid in a sump of the electric motor system is between 70°C and 125°C and the temperature of copper windings in a stator of the electric motor system is between 150°C and 180°C; lubricating gears and clutches in the electric motor system with the lubricating and cooling fluid and simultaneously cooling the electric machine in the electric motor system by contacting the copper windings with the lubricating and cooling fluid; and wherein the lubricating and cooling fluid contains: an oil of lubricating viscosity comprising an API Group III base oil, an API Group IV base oil, or a mixture thereof; at least one thiadiazole or hydrocarbyl-substituted derivative thereof that delivers 1000 ppm to 1500 ppm of sulfur to the lubricating and cooling fluid; an optional sulfidized ester that delivers 300 ppm or less of sulfur to the lubricating and cooling fluid; a dispersant system comprising (i) a first dispersant obtained from polyisobutylene having a number average molecular weight of 1500 to 2500 and that delivers up to 700 ppm of nitrogen to the lubricating and cooling fluid and (ii) a second dispersant having a number average molecular weight of 1000 or less and that delivers up to 150 ppm of nitrogen to the lubricating and cooling fluid; an alkoxylated aliphatic amine that delivers up to 20 ppm of nitrogen to the lubricating and cooling fluid; an ether amine that delivers up to 20 ppm of nitrogen to the lubricating and cooling fluid; and wherein at least one of the first dispersant and the second dispersant is borated and phosphated such that the total amount of boron and phosphorus in the dispersant system relative to nitrogen in the dispersant system is 0.5 to 0.7, and wherein the first dispersant and the second dispersant deliver up to 100 ppm of total boron and phosphorus per 1000 number average molecular weight of combined polyisobutylene moieties in the dispersant system.

2. The method of claim 1, wherein the at least one thiadiazole or hydrocarbyl- substituted derivative thereof comprises one or more compounds having the structure of Formula I: wherein each R1 is independently hydrogen or sulfur; each R2 is independently an alkyl group; n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, n of the adjacent R2 moiety is 1; and wherein at least one R1 is sulfur.

3. The method of claim 1, wherein the at least one thiadiazole or hydrocarbyl- substituted derivative thereof is a thiadiazole mixture of hydrocarbyl-substituted derivatives of 2,5-dimercapto-l,3,4-thiadiazole, including one of 2,5-bis-(nonyldithio)-l,3,4- thiadiazole, 2,5-mono-(nonyldithio)-l,3,4-thiadiazole, or a combination thereof.

4. The method of claim 1, wherein the lubricating and cooling fluid further comprises a fatty diamine delivering up to 3 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the alkoxylated aliphatic amine, ether amine, and fatty diamine deliver nitrogen to the lubricating and cooling fluid in an amount of 30 ppm or less of nitrogen.

5. The method of claim 4, wherein the alkoxylated aliphatic amine is a di(hydroxyalkyl) aliphatic tertiary amine comprising hydroxyalkyl groups each containing 2 to 4 carbon atoms and further comprising an acyclic hydrocarbyl group containing 16 to 25 carbon atoms; and / or wherein the ether amine comprises isodecyloxypropylamine; and / or wherein the fatty diamine comprises n-oleyl-1,3-diaminopropane.

6. The method of claim 4, wherein the alkoxylated aliphatic amine and ether amine each deliver up to 15 ppm of nitrogen to the lubricating and cooling fluid, and wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof is a thiadiazole mixture of hydrocarbyl-substituted derivatives of 2,5-dimercapto-1,3,4-thiadiazole, including one of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole, 2,5-mono-(nonyldithio)-1,3,4- thiadiazole, or combinations thereof, and wherein the thiadiazole mixture and optional sulfidized ester deliver 1400 ppm to 1800 ppm of sulfur to the lubricating and cooling fluid.

7. The method of claim 1, wherein the first dispersant is present in an amount that delivers up to 500 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the second dispersant is present in an amount that delivers up to 115 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the first dispersant is obtained from a polyisobutylene having a number average molecular weight of 2000 to 2400, and the second dispersant is obtained from a polyisobutylene having a number average molecular weight of 950; and / or wherein the first dispersant delivers boron and phosphorus to the lubricating and cooling fluid in an amount of 100 ppm or less of boron and 250 ppm or less of phosphorus.

8. The method of claim 1, wherein the oil of lubricating viscosity comprises the Group III base oil.

9. The method of claim 1, wherein the oil of lubricating viscosity comprises a gas-to-liquid (GTL) base oil.

10. The method of claim 1, wherein the oil of lubricating viscosity comprises a polyalphaolefin (PAO) base oil.

11. The method of claim 1, wherein the lubricating and cooling fluid has an initial conductivity of 60 nS / M or less, as measured by modified ASTM D2624-15 at 20 Hz and 100°C using the lubricating and cooling fluid.

12. The method of claim 1, wherein the lubricating and cooling fluid has a sulfurized ester delivering 180 ppm to 300 ppm of sulfur to the lubricating and cooling fluid; and / or wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof and the sulfurized ester deliver 1400 ppm to 1800 ppm of sulfur to the lubricating and cooling fluid; and / or wherein the sulfurized ester comprises a transesterified triglyceride.

13. A lubricating and cooling fluid for an electric motor system, the lubricating and cooling fluid comprising: a major base oil of lubricating viscosity, the major base oil of lubricating viscosity comprising an API Group III base oil, an API Group IV base oil, or a mixture thereof; at least one thiadiazole or hydrocarbyl-substituted derivative thereof delivering 1000 ppm to 1500 ppm of sulfur to the lubricating and cooling fluid; an optional sulfurized ester delivering up to 300 ppm of sulfur to the lubricating and cooling fluid; a dispersant system comprising (i) a first dispersant obtained from a polyisobutylene having a number average molecular weight of 1500 to 2500 and delivering nitrogen to the lubricating and cooling fluid in an amount of 700 ppm or less of nitrogen and (ii) a second dispersant obtained from a polyisobutylene having a number average molecular weight of 1000 or less and delivering nitrogen to the lubricating and cooling fluid in an amount of 150 ppm or less of nitrogen; an alkoxylated fatty amine delivering up to 20 ppm of nitrogen to the lubricating and cooling fluid; an ether amine delivering up to 20 ppm of nitrogen to the lubricating and cooling fluid; wherein at least one of the first dispersant and the second dispersant is borated and phosphated such that the total amount of boron and phosphorus in the dispersant system is 0.5 to 0.7 relative to the nitrogen in the dispersant system, and wherein the first dispersant and the second dispersant deliver up to 100 ppm of total boron and phosphorus per 1000 number average molecular weight of combined polyisobutylene moieties in the dispersant system; wherein the lubricating and cooling fluid has a conductivity of 60 nS / M or less measured by ASTM D2624-15 at 20 Hz and 100°C.

14. The lubricating and cooling fluid of claim 13, wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof comprises one or more compounds having the structure of Formula I: wherein each R1 is independently hydrogen or sulfur; each R2 is independently an alkyl group; n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, n of the adjacent R2 moiety is 1; and wherein at least one R1 is sulfur.

15. The lubricating and cooling fluid of claim 13, wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof comprises one or more compounds having the structure of Formula II: wherein each R1 is independently hydrogen or sulfur; each R2 is independently an alkyl group; n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, n of the adjacent R2 moiety is 1; and wherein at least one R1 is sulfur.

15. The lubricating and cooling fluid of claim 13, wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof comprises a thiadiazole mixture of hydrocarbyl-substituted derivatives of 2,5-dimercapto-l,3,4-thiadiazole, including one of 2,5-bis-(nonyldithio)-l,3,4-thiadiazole, 2,5-mono-(nonyldithio)-l,3,4- thiadiazole, or combinations thereof.

16. The lubricating and cooling fluid of claim 13, wherein the fluid further comprises a fatty diamine delivering up to 3 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the aliphatic amine, ether amine, and fatty diamine deliver up to 30 ppm of nitrogen to the lubricating and cooling fluid.

17. The lubricating and cooling fluid of claim 16, wherein the alkoxylated aliphatic amine is a di(hydroxyalkyl) aliphatic tertiary amine comprising hydroxyalkyl groups each containing 2 to 4 carbon atoms and further comprising an acyclic hydrocarbyl group containing 16 to 25 carbon atoms; and / or wherein the ether amine is isodecyloxypropylamine; and / or wherein the fatty diamine is n-oleyl-l,3-diaminopropane.

18. The lubricating and cooling fluid of claim 16, wherein the alkoxylated aliphatic amine and ether amine each deliver up to 15 ppm of nitrogen to the lubricating and cooling fluid, and wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof is a thiadiazole mixture of hydrocarbyl-substituted derivatives of 2,5-dimercapto-l,3,4-thiadiazole, including one of 2,5-bis-(nonyldithio)-l,3,4-thiadiazole, 2,5-mono-(nonyldithio)-l,3,4- thiadiazole, or combinations thereof, and wherein the thiadiazole mixture and optional sulfidized ester deliver 1400 ppm to 1800 ppm of sulfur to the lubricating and cooling fluid.

19. The lubricating and cooling fluid of claim 13, wherein the first dispersant is present in an amount that delivers up to 500 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the second dispersant is present in an amount that delivers up to 115 ppm of nitrogen to the lubricating and cooling fluid; and / or wherein the first dispersant is obtained from a polyisobutylene having a number average molecular weight of 2000 to 2400, and the second dispersant is obtained from a polyisobutylene having a number average molecular weight of 950; and / or wherein the first dispersant delivers boron and phosphorus to the lubricating and cooling fluid in an amount of 100 ppm or less of boron and 250 ppm or less of phosphorus; and / or wherein the first dispersant is obtained from a polyisobutylene having a number average molecular weight of 2000 to 2400, and the second dispersant is obtained from a polyisobutylene having a number average molecular weight of 950.

20. The lubricating and cooling fluid of claim 13, wherein the base oil comprises a Group III base oil.

21. The lubricating and cooling fluid of claim 13, wherein the base oil comprises a gas-to-liquid (GTL) base oil.

22. The lubricating and cooling fluid of claim 13, wherein the base oil comprises a polyalphaolefin (PAO) base oil.

23. The lubricating and cooling fluid of claim 13, wherein the lubricating and cooling fluid has a sulfidized ester delivering 180 ppm to 300 ppm of sulfur to the lubricating and cooling fluid; and / or wherein the at least one thiadiazole or hydrocarbyl-substituted derivative thereof and the sulfidized ester deliver 1400 ppm to 1800 ppm of sulfur to the lubricating and cooling fluid.

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