Low Viscosity Lubricating Fluids for Electric Motor Systems

Abstract

To provide an electric motor lubricating fluid for use in a low viscosity electric motor system fluid, wherein the electric motor lubricating fluid has acceptable wear performance, as well as good electrical conductivity and oxidation stability.SOLUTION: An electric motor lubricating fluid comprises a lubricating base oil; a succinimide dispersant having about 0.5 to about 1 wt.% of nitrogen, post-treated with phosphorus-containing compounds and boron-containing compounds, delivering about 70 to about 140 ppm of phosphorus and about 150 to about 300 ppm of nitrogen; an amine salt of phosphate ester providing about 40 to 70 ppm of phosphorus; an oil-soluble phosphorus anti-wear additive including an ashless dialkyldithiophosphate providing about 40 to about 70 ppm of phosphorus to the electric motor lubricating fluid; and a sulfur-providing additive including thiadiazole or a derivative thereof providing up to 950 ppm of sulfur to the electric motor lubricating fluid, wherein the electric motor lubricating fluid has a kV100°C of about 4.5 cSt or less and a total phosphorus content of about 150 to about 250 ppm.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to lubricating fluids for electric motor systems and methods for lubricating gears and clutches in electric motor systems. In particular, the disclosed methods and lubricating fluids relate to low viscosity lubricating fluids for use in electric motors of electric or hybrid electric vehicles that include an oil of lubricating viscosity and at least one higher molecular weight dispersant. [Background technology]

[0002] A major challenge in developing an electric vehicle powertrain lubricant is to ensure lubricant compatibility with the charged components in the powertrain while achieving acceptable wear and friction performance and maintaining oxidation stability. Because the lubricant in an electric or hybrid electric vehicle may also come into contact with components in the electric motor, the electrical conductivity of the fluid must also be relatively low to prevent electrostatic build-up and discharge of the charged components.

[0003] To improve efficiency, lubricant manufacturers often attempt to reduce the viscosity of the lubricant, but lower viscosity fluids are often less desirable for the stringent wear and friction tests often required by industrial and / or automotive manufacturers. Thus, low viscosity fluids may often require additional anti-wear additives to meet the required wear tests. However, adding these additional additives often increases the electrical conductivity and decreases the oxidative stability of the lubricant. For example, a lubricant having a kV100°C (ASTM D445) of about 4.5 cSt or less may require a higher amount of anti-wear additives to achieve the required wear performance than would be required in a higher viscosity lubricant, but the addition of certain anti-wear additives may result in increased conductivity and decreased oxidative stability. In particular, it has previously been difficult for low viscosity lubricants having a kV100°C of about 4.5 cSt or less, or 3.5 cSt or less, or 3.0 cSt or less, to pass stringent FZG wear tests, such as the demanding A10 / 16.6R / 90 scuffing test of CEC L-84-02, while also exhibiting low conductivity and maintaining oxidative stability. Summary of the Invention

[0004] In one embodiment, an electric motor lubrication fluid suitable for electric or hybrid electric vehicles is described herein. In the method, an electric motor lubricating fluid comprises one or more base oils of lubricating viscosity; a succinimide dispersant derived from a polyisobutylene having a number average molecular weight of about 2,000 or greater, having about 0.5 to about 1 weight percent nitrogen, and post-treated with a phosphorus-containing compound and a boron-containing compound to deliver about 70 to about 140 ppm phosphorus and about 150 to about 300 ppm nitrogen to the electric motor lubricating fluid; an oil soluble phosphorus antiwear additive comprising an amine salt of a phosphoric acid ester providing about 40 to about 70 ppm phosphorus to the electric motor lubricating fluid; and a sulfur providing additive comprising a thiadiazole or derivative thereof providing up to about 950 ppm sulfur to the electric motor lubricating fluid, wherein the electric motor lubricating fluid has a kV 100° C. of about 4.5 cSt or less and about 150 to about 250 ppm total phosphorus.

[0005] In other approaches or embodiments, the electric motor lubrication described in the preceding paragraph may include one or more of the optional features or embodiments in any combination. These optional features or embodiments may include one or more of the following: the amine salt of a phosphoric acid ester has the structure of Formula I or a solvate or hydrate thereof:

[0006] [ka] R1 and R2 are independently hydrogen or a linear, branched, or cyclic hydrocarbyl group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R3, R4, R5, and R6 are independently hydrogen or a hydrocarbyl group, and at least one of R3 to R6 is a hydrocarbyl group; and / or R1 and R2 are independently C3 to C6. 10 At least one of R3, R4, R5 and R6 is an alkyl group. 10 ~C 20and / or the number average molecular weight of the high molecular weight polyisobutylene is from about 2,000 to about 2,300, and / or the electric motor lubricating fluid comprises from about 2 to about 4 weight percent succinimide dispersant, and / or the succinimide dispersant, the amine salt of a phosphate ester, the ashless dialkyl dithiophosphate, and the thiadiazole or derivative thereof are provided in an additive concentrate, the additive concentrate having a kV100°C of from about 15 to about 80 cSt, and / or the ratio of the kV100°C of the additive concentrate to the kV100°C of the electric motor lubricating fluid is from about 5:1 to about 30:1, and / or the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after the electric motor lubricating fluid has been aged in accordance with CEC L-48-A), and / or the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after the electric motor lubricating fluid has been aged in accordance with CEC L-84-02, and / or and / or the electric motor lubricating fluid has an electrical conductivity of about 60 nS / M or less, measured at 20 Hz and 100° C. using the electric motor lubricating fluid by a modified conductivity test in accordance with ASTM D2624-15, and / or the oil soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate is made by a process comprising: (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; and further reacting the reaction product with an unsaturated carboxylic acid to form the oil soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate; and / or the ashless dialkyl dithiophosphate comprises a compound of formula II or a salt thereof,

[0007] [ka] R7 and R8 are independently a C3-C8 straight or branched chain alkyl group, R9 is -H or -CH3, and / or the ashless dialkyl dithiophosphate is 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methyl-propanoic acid, and / or the thiadiazole or derivative thereof comprises one or more compounds having the structure of formula III;

[0008] [ka] Each R 10 is independently hydrogen or sulfur; 11 are independently an alkyl group, n is an integer of 0 or 1, and R 10 If is hydrogen, the adjacent R 11 The integer n in the part is 0, and R 10 If is sulfur, the adjacent R 11 The moiety n is 1 and has at least one R 10 is sulfur, and / or further includes one or more metal-containing detergent additives providing up to about 50 ppm calcium to the electric motor lubricating fluid.

[0009] In yet another embodiment, the present disclosure provides an additive concentrate suitable for electric motor lubricating fluids. In the method, the additive concentrate comprises a succinimide dispersant derived from a high molecular weight polyisobutylene having a number average molecular weight of about 2,000 or greater, having about 0.5 to about 1 weight percent nitrogen, and post-treated with a phosphorus-containing compound and a boron-containing compound and present in an amount to deliver about 1400 to about 2450 ppm phosphorus and about 3000 to about 5400 ppm nitrogen to the dispersant additive concentrate; an amine salt of a phosphoric acid ester providing about 1000 to 1500 ppm phosphorus to the additive concentrate; an oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate providing about 800 ppm to about 1300 ppm phosphorus to the additive concentrate; and a sulfur providing additive comprising a thiadiazole or derivative thereof providing sulfur to the additive concentrate, but not exceeding about 18,000 ppm sulfur, the additive concentrate having a kV100°C of about 15 cSt to about 80 sCt.

[0010] In other embodiments, the additive concentrate of the preceding paragraph may include one or more of the optional features or embodiments in any combination. These optional features or embodiments may include one or more of the following: the amine salt of a phosphoric acid ester has the structure of Formula I, or a solvate or hydrate thereof:

[0011] [ka] R1 and R2 are independently hydrogen or a linear, branched, or cyclic hydrocarbyl group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R3, R4, R5, and R6 are independently hydrogen or a hydrocarbyl group, at least one of R3 to R6 is a hydrocarbyl group, and / or R1 and R2 are independently a C3 to C10 alkyl group, at least one of R3, R4, R5, and R6 is a C 10 ~C 20 and / or the number average molecular weight of the high molecular weight polyisobutylene is from about 2,000 to about 2,300, and / or the succinimide dispersant comprises an additive concentrate of from about 40 to about 70 weight percent, and / or the oil soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate is made by a process comprising the steps of: (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product and further reacting the reaction product with an unsaturated carboxylic acid to form the oil soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, and / or the ashless dialkyl dithiophosphate comprises a compound of formula II or a salt thereof:

[0012] [ka] R7 and R8 are independently a C3-C8 straight or branched chain alkyl group, R9 is -H or -CH3, and / or the ashless dialkyl dithiophosphate is 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methyl-propanoic acid, and / or the thiadiazole or derivative thereof comprises one or more compounds having the structure of formula III;

[0013] [ka] Each R 10 is independently hydrogen or sulfur; 11 are independently an alkyl group, n is an integer of 0 or 1, and R 10 If is hydrogen, the adjacent R 11The integer n in the part is 0, and R 10 If is sulfur, the adjacent R 11 The moiety n is 1 and has at least one R 10 is sulfur, and / or further comprises one or more metal-containing detergent additives providing the additive concentrate with up to about 950 ppm calcium.

[0014] In yet another embodiment, a method for lubricating a driveline component including an electric motor is also described herein. In one embodiment, the method includes lubricating the driveline component with an electric motor lubricating composition, the electric motor lubricating composition contacting a part of the electric motor, the electric motor lubricating composition comprising (i) one or more base oils of lubricating viscosity and (ii) a succinimide dispersant derived from a high molecular weight polyisobutylene having a number average molecular weight of about 2,000 or greater, having about 0.5 to about 1 weight percent nitrogen, and post-treated with a phosphorus-containing compound and a boron-containing compound, and having about 70 to about 140 ppm phosphorus and about 150 to about 300 ppm nitrogen. (iii) an amine salt of a phosphate ester providing about 40 to about 70 ppm of phosphorus to the electric motor lubricating fluid; (iv) an oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate providing about 40 to about 70 ppm of phosphorus to the electric motor lubricating fluid; and (v) a sulfur providing additive comprising a thiadiazole or derivative thereof providing sulfur but not more than about 950 ppm of sulfur to the electric motor lubricating fluid, wherein the electric motor lubricating fluid has a kV100°C of about 4.5 cSt or less, a kV100°C of about 150 to about 250 ppm of total phosphorus, and an electrical conductivity of about 37 nS / M or less, as measured by a modified conductivity test in accordance with ASTM D2624-15 using the electric motor lubricating fluid, measured at 20 Hz and 100°C.

[0015] In further embodiments, the method for lubricating driveline components, including electric motors, of the preceding paragraph may further include one or more optional method steps, features, or embodiments in any combination. These optional method steps, features, or embodiments may include one or more of the following: the amine salt of a phosphoric acid ester has the structure of Formula I, or a solvate or hydrate thereof:

[0016] [ka] R1 and R2 are independently hydrogen or a linear, branched, or cyclic hydrocarbyl group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R3, R4, R5, and R6 are independently hydrogen or a hydrocarbyl group, and at least one of R3 to R6 is a hydrocarbyl group; and / or R1 and R2 are independently C3 to C6. 10 At least one of R3, R4, R5 and R6 is an alkyl group. 10 ~C 20 and / or the electric motor lubricating fluid comprises from about 2 to about 4 weight percent succinimide dispersant, and / or the succinimide dispersant, the amine salt of a phosphoric acid ester, the oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate, and the sulfur-providing additive comprising a thiadiazole or derivative thereof are provided in an additive concentrate having a kV100°C of from about 15 to about 80 cSt, and / or the ratio of the kV100°C of the additive concentrate to the kV100°C of the electric motor lubricating fluid is from about 5:1 to about 30:1, and the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after the electric motor lubricating fluid is aged according to CEC L-48-A, and the electric motor lubricating fluid is aged according to CEC L-84-02, and / or the electric motor lubricating fluid comprises from about 2 to about 4 weight percent succinimide dispersant, and / or the succinimide dispersant, the amine salt of a phosphoric acid ester, the oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate, and the sulfur-providing additive comprising a thiadiazole or derivative thereof are provided in an additive concentrate having a kV100°C of from about 15 to about 80 cSt, and / or Achieves a failure load stage of at least 8 in the A10 / 16.6R / 90 Scuffing Test, and / or the oil soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate is made by a process comprising: (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; and further reacting the reaction product with an unsaturated carboxylic acid to form the oil soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, and / or the ashless dialkyl dithiophosphate comprises a compound of formula II or a salt thereof.

[0017] [ka] R7 and R8 are independently a C3-C8 straight or branched chain alkyl group, R9 is -H or -CH3, and / or the ashless dialkyl dithiophosphate is 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methyl-propanoic acid, and / or the thiadiazole or derivative thereof comprises one or more compounds having the structure of formula III;

[0018] [ka] Each R 10 is independently hydrogen or sulfur; 11 are independently an alkyl group, n is an integer of 0 or 1, and R 10 If is hydrogen, the adjacent R 11 The integer n in the part is 0, and R 10 If is sulfur, the adjacent R 11 The moiety n is 1 and has at least one R 10 is sulfur, and / or the electric motor lubricating composition further comprises one or more metal-containing detergent additives providing up to about 50 ppm of calcium to the electric motor lubricating composition.

[0019] In yet another embodiment, the present disclosure provides for the use of an additive concentrate in an electric motor lubricating composition and / or the use of an electric motor lubricating composition to achieve about 150 to about 250 ppm total phosphorus, and an electrical conductivity of about 37 nS / M or less, kV100°C, as measured by a modified conductivity test in accordance with ASTM D2624-15, measured at 20 Hz and 100°C, using an electric motor lubricating fluid. In another embodiment, the use includes an electric motor lubricating composition having (i) one or more base oils of lubricating viscosity; (ii) a succinimide dispersant derived from a high molecular weight polyisobutylene having a number average molecular weight of greater than or equal to about 2,000, having from about 0.5 to about 1 weight percent nitrogen, and post-treated with a phosphorus-containing compound and a boron-containing compound to deliver from about 70 to about 140 ppm phosphorus and from about 150 to about 300 ppm nitrogen to the electric motor lubricating fluid; (iii) an amine salt of a phosphoric acid ester providing from about 40 to about 70 ppm phosphorus to the electric motor lubricating fluid; (iv) an oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate providing from about 40 to about 70 ppm phosphorus to the electric motor lubricating fluid; and (v) a sulfur providing additive comprising a thiadiazole or derivative thereof providing sulfur to the electric motor lubricating fluid, but not exceeding about 950 ppm sulfur. In still other approaches or embodiments, the use may also include any other embodiment of the electric motor lubricant composition, any other embodiment of the method, or any other embodiment of the additive concentrate, as described above in this Summary.

[0020] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.

[0021] The following definitions are provided to clarify the meaning of certain terms used herein.

[0022] The terms "lubricating oil," "lubricant composition," "lubricating composition," "lubricant," and "lubricating and cooling fluid" refer to a finished lubricating product that comprises a major amount of a base oil and a minor amount of an additive composition.

[0023] As used herein, the terms "additive package," "additive concentrate," and "additive composition" refer to that portion of a lubricating oil composition other than a majority of base oil.

[0024] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its normal sense, which is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having a predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from hydrocarbon substituents, the substituted hydrocarbon substituents containing one or more of halo, hydroxyl, alkoxy, mercapto, nitro, nitroso, amino, pyridyl, furyl, imidazolyl, oxygen, and nitrogen, and no more than two non-hydrocarbon substituents are present for every 10 carbon atoms in the hydrocarbyl group.

[0025] As used herein, the term "percent by weight" or "wt%" means the percentage that the recited component represents relative to the weight of the entire composition, unless otherwise specified.

[0026] The terms "soluble", "oil-soluble" or "dispersible" used herein may, but do not necessarily, indicate that a compound or additive is soluble, dissolvable, miscible or suspendable in oil in all proportions. However, the terms mean that they are, for example, soluble, suspendable, soluble or stably dispersible in oil to a sufficient degree to exert their intended effect in the environment in which the oil is used. Furthermore, if desired, the incorporation of other additives may also allow the incorporation of higher levels of the specific additive.

[0027] As used herein, the term "alkyl" refers to straight, branched, cyclic, and / or substituted saturated chain moieties of about 1 to about 200 carbon atoms.

[0028] As used herein, the term "alkenyl" refers to straight, branched, cyclic, and / or substituted saturated chain moieties of about 3 to about 30 carbon atoms.

[0029] As used herein, the term "aryl" refers to mono- and polycyclic aromatic compounds that may contain alkyl, alkenyl, alkylaryl, amino, hydroxyl, alkoxy, halo substituents, and / or heteroatoms such as, but not limited to, nitrogen and oxygen.

[0030] As used herein, "number average molecular weight" or "Mn" is determined by gel permeation chromatography (GPC) using commercially available polystyrene standards (having Mn of about 180 to about 18,000) as calibration standards.

[0031] Throughout this disclosure, the terms "comprises," "includes," "contains," and the like are considered to be open ended and should be understood to include any element, step, or ingredient not expressly recited. The phrase "consisting essentially of" is meant to include any explicitly recited element, step, or ingredient, as well as any additional elements, steps, or ingredients that do not materially affect the basic and novel aspects of the invention. This disclosure also contemplates that any composition described using the terms "comprises," "includes," "contains" should be construed as including a disclosure of the same composition "consisting essentially of" or "consisting of" that specifically recited ingredient. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] According to exemplary embodiments, described herein are electric motor lubricating fluids suitable for electric or hybrid electric vehicles that have low viscosities at kV100°C of about 4.5 cSt or less, about 3.5 cSt or less, or about 3.0 cSt or less, and still be capable of passing stringent FZG scuffing tests such as the A10 / 16.6R / 90 test of CEC L-84-02, while achieving good electrical conductivity and maintaining oxidation stability. However, what is surprising about the lubricating fluids herein is that it has been found that certain additive combinations, including succinimide dispersants derived from relatively high molecular weight polyisobutylenes, are useful for achieving acceptable wear, conductivity, and oxidation performance. Selected relatively high molecular weight dispersants described herein, when incorporated into an additive concentrate, result in an additive concentrate having a relatively high viscosity. Such high viscosity additive concentrates have not heretofore been used in low viscosity finished lubricants (e.g., finished lubricants having a kV100°C of about 4.5 cSt or less, about 3.5 cSt or less, or about 3.0 cSt or less) that require stringent wear protection, low conductivity, and oxidation stability.

[0033] It was not expected that relatively high viscosity additive concentrates having relatively high molecular weight succinimide dispersants would be suitable for forming low viscosity finished lubricants capable of passing the wear, conductivity, and oxidation performance tests of electric and / or hybrid electric vehicles. However, when selected relatively high molecular weight succinimide dispersants herein were combined with other lubricant additives having specific elemental relationships to form finished lubricants, the finished lubricants herein achieved low viscosity, acceptable scuffing performance, adequate conductivity, and oxidation stability for drivelines having electric or hybrid electric motors.

[0034] It has been found herein that relatively high molecular weight polyisobutylene dispersants can be provided in fluids for such electrical or hybrid-electric applications having low final fluid viscosity when such high molecular weight dispersants are also provided in specific amounts in the final fluid in combination with selected amounts of phosphorus, nitrogen, and / or sulfur from other additives including, for example, amine salts of phosphoric acid esters, ashless dialkyldithiophosphates, and thiadiazoles or derivatives thereof. In one approach, for example, the fluids described herein are derived from polyisobutylene having a number average molecular weight of about 2,000 or greater, maximum (ii) an amine salt of a phosphate ester providing from about 45 to about 75 ppm of phosphorus to the electric motor lubricating fluid; (iii) an oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate providing from about 40 to about 70 ppm of phosphorus to the electric motor lubricating fluid; and (iv) a sulfur providing additive comprising a thiadiazole or derivative thereof providing sulfur to the lubricant but not greater than about 950 ppm of sulfur to the electric motor lubricating fluid, wherein the electric motor lubricating fluid has a conductivity of about 4.5 cSt or less, about 3.5 cSt or less, about 3.0 cSt or less (ASTM D4450), about 150 to about 250 ppm total phosphorus, and an electrical conductivity of about 60 nS / M or less. In yet other embodiments, the lubricants described herein may also contain an amount of calcium from a detergent additive (e.g., up to about 50 ppm calcium in the lubricant, or up to about 950 ppm calcium in a neutral to low-based detergent additive concentrate). Each component additive is further described below.

[0035] Succinimide Dispersants: The electric motor lubricating fluids herein contain a dispersant system having at least one oil-soluble ashless dispersant, which is a succinimide dispersant derived from a relatively high molecular weight polyisobutylene having a number average molecular weight of about 2000 or greater, which is also post-treated with a phosphorus-containing compound and a boron-containing compound. Such relatively high molecular weight succinimide dispersants, at suitable treat rates, result in dispersant additive concentrates having a kV100°C of about 15 to about 80 cSt (ASTM D445). The succinimide dispersants herein can be derived from a relatively high molecular weight hydrocarbyl-substituted dicarboxylic acid or anhydride reacted with a polyalkylene polyamine. Succinimide dispersants and their preparation are disclosed at least in U.S. Pat. No. 7,897,696 and / or U.S. Pat. No. 4,234,435, which are incorporated herein by reference.

[0036] The relatively high molecular weight hydrocarbyl portion of the hydrocarbyl-dicarboxylic acid or anhydride thereof may be derived from a butene polymer, such as a polymer of isobutylene. Suitable polyisobutylenes for use herein include those formed from polyisobutylene or highly reactive polyisobutylenes having a terminal vinylidene content of at least about 60%, such as from about 70% to about 90% or more. Suitable polyisobutylenes may include those prepared using BF3 catalysts.

[0037] The dispersants herein have a relatively high molecular weight, and thus the number average molecular weight of the polyisobutylene substituent of the dispersants herein may vary from at least about 2,000, and in some cases up to about 3,000, as determined by gel permeation chromatography (GPC) using polystyrene (having a number average molecular weight of 180 to about 18,000) as a calibration standard. The GPC method further provides weight average molecular weight distribution information. See also, for example, W.W. Yau, J.J. Kirkland and D.D. Ly, "Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New York, 1979, which is incorporated herein by reference.

[0038] The polyisobutylene moieties in the dispersants herein may also preferably have a molecular weight distribution (MWD), also referred to as the polydispersity index, determined by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn). In some approaches or embodiments, suitable polyisobutylene moieties may have an Mw / Mn of less than about 3.0, or less than about 2.8, or less than about 2.5, while in other approaches suitable polyisobutylene substituents have a polydispersity of from about 1.5 to about 3.0, or from about 2.0 to about 3.0.

[0039] Suitable dicarboxylic acids or anhydrides for forming the dispersant can be selected from carboxylic reactants including corresponding acid halides and C1-C4 aliphatic esters, such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethyl maleic acid, anhydride, dimethyl maleic anhydride, ethyl maleic acid, dimethyl maleic acid, hexyl maleic acid, etc. In some approaches, the molar ratio of dicarboxylic acid or anhydride to hydrocarbyl moieties in the reaction mixture used to make the hydrocarbyl dicarboxylic acid or anhydride can vary widely. Thus, the charge molar ratio can vary from 5:1 to 1:5, for example, from 3:1 to 1:3. In some embodiments, a particularly suitable molar ratio of acid or anhydride to hydrocarbyl moieties is 1:1 to less than 1.6:1. In other embodiments, other useful charge molar ratios of dicarboxylic acid or anhydride to hydrocarbyl moieties can be from 1:1 to 1.5:1, or from 1:1 to 1.4:1, or from 1.1:1 to 1.3:1, or from 1:1 to 1.2:1.

[0040] Any of a number of polyalkylene polyamines can be used in preparing the dispersant additives herein. Non-limiting exemplary polyamines can include aminoguanidine bicarbonate (AGBC), diethylene triamine (DETA), triethylene tetramine (TETA), tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA) and heavy polyamines. Heavy polyamines can include mixtures of polyalkylene polyamines with minor amounts of polyamine oligomers such as TEPA and PEHA, but with predominantly oligomers with 7 or more nitrogen atoms per molecule, 2 or more primary amines, and with more extensive branching than conventional polyamine mixtures. Typically, these heavy polyamines have an average of 6.5 nitrogen atoms per molecule. Further non-limiting polyamines that can be used to prepare hydrocarbyl-substituted succinimide dispersants are disclosed in U.S. Patent No. 6,548,458, the entire disclosure of which is incorporated herein by reference. In some embodiments, the charge molar ratio of the hydrocarbyl dicarboxylic acid or anhydride to the polyalkylene polyamine can be from about 1:1 to about 3.0:1. In one embodiment, the dispersant in the present disclosure described herein can be the reaction product of polyisobutenyl succinic anhydride (PIBSA) and a polyamine, such as a heavy polyamine, in which the charge molar ratio of the polyisobutenyl-substituted succinic anhydride to the polyamine is from about 1.7:1 to about 2.5:1.

[0041] As mentioned above, the polymeric succinimide dispersants of the present invention can be post-treated with a boron compound. Suitable boron compounds useful in forming the dispersants herein include any boron compound or mixture of boron compounds capable of introducing a boron-containing species into the ashless dispersant. Any boron compound, organic or inorganic, capable of undergoing such a reaction can be used. Thus, boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF4 boric acid, such as boronic acids (e.g., alkyl-B(OH)2, or 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 such boric acids can be used. The use of complexes of boron trihalides with ethers, organic acids, inorganic acids, or hydrocarbons is a convenient means of introducing the boron reactant into the reaction mixture. Such complexes are known and are exemplified by boron trifluoride-diethyl ether, boron trifluoride-phenol, boron trifluoride-phosphoric acid, boron trichloride-chloroacetic acid, boron tribromide-dioxane, and boron trifluoride-methyl ethyl ether.

[0042] The polymeric succinimide dispersants of the present invention may also be post-treated with a phosphorus compound. Suitable phosphorus compounds for forming the dispersants herein include any phosphorus compound or mixture of phosphorus compounds capable of introducing phosphorus-containing species into the ashless dispersant. Thus, any phosphorus compound, organic or inorganic, capable of undergoing such a reaction may be used. Thus, such inorganic phosphorus compounds may be used as inorganic phosphoric acid and inorganic phosphorus oxides, including their hydrates. Exemplary organophosphorus compounds include full and partial esters of phosphoric acid, such as the mono-, di-, and triesters of phosphoric, thiophosphoric, dithiophosphoric, trithiophosphoric, and tetrathiophosphoric acids; mono-, di-, and triesters of phosphorous, thiophosphorous, dithiophosphorous, and trithiophosphorous acids; trihydrocarbyl phosphine oxides; trihydrocarbyl phosphine sulfides; mono- and dihydrocarbyl phosphonates, (RPO(OR')(OR"), where R and R' are hydrocarbyl and R" is a hydrogen atom or a hydrocarbyl group, and their mono-, di-, and trithio analogs; mono- and dihydrocarbyl phosphonites, (RP(OR') (OR"), where R and R' are hydrocarbyl and R" is a hydrogen atom or a hydrocarbyl group, and their mono- and dithio analogs. Thus, such compounds may be referred to, for example, as phosphorous acid (H3PO3, sometimes represented as H2(HPO3) and sometimes referred to as ortho-phosphorous acid or phosphoric acid), phosphoric acid (H3PO4, sometimes referred to as orthophosphoric acid), hypophosphoric acid (H4P2O6), metaphosphoric acid (HPO3), pyrophosphoric acid (H4P2O7), hypophosphorous acid (H3PO2, sometimes referred to as phosphinic acid), pyrophosphorous acid (H4P2O5, sometimes referred to as pyrophosphonic acid), phosphinic acid (H3PO), tripolyphosphoric acid (H5P3O4), triphosphoric acid (H5P3O5), tri ... 10 ), tetrapolyphosphate (H5P4O 13), trimetaphosphoric acid (H3P3O9), phosphorus trioxide, phosphorus tetroxide, phosphorus pentoxide, etc. Phosphorotetrathioic acid (H3PS4), phosphoromonothioic acid (H3PO3S), phosphorodithioic acid (H3PO2S2), phosphorotrithioic acid (H3POS3), phosphorus sesquisulfide, phosphorus heptasulfide, and phosphorus pentasulfide (P2S5, P4S 10 Partial or full sulfur analogs such as sulphur fluoride (sometimes referred to as sulphur fluoride) may also be used in forming dispersants for the present disclosure. Inorganic phosphorus halide compounds such as PCl3, PBr3, POCl3, PSCl3, etc. may also be used.

[0043] Similarly, organophosphorus compounds such as mono-, di-, and triesters of phosphoric acid (e.g., trihydrocarbyl phosphates, dihydrocarbyl monoacid phosphates, monohydrocarbyl diacid phosphates, and mixtures thereof), mono-, di-, and triesters of phosphorous acid (e.g., trihydrocarbyl phosphites, dihydrocarbyl hydrogen phosphites, hydrocarbyl diacid phosphites, and mixtures thereof), esters of phosphonic acids (both "primary" RP(O)(OR)2 and "secondary" RP(O)(OR)), esters of phosphinic acids, phosphonyl halides ( For example, RP(O)Cl2 and RP(O)Cl), halophosphates (e.g., (RO)PCl2 and (RO)PCl), halophosphites (e.g., ROP(O)Cl2 and (RO)2P(O)Cl), tertiary pyrophosphate esters (e.g., (RO)2P(O)-OP(O)(OR)2), and full or partial sulfur analogs of any of the foregoing organophosphorus compounds can be used, with each hydrocarbyl group containing up to 100 carbon atoms, preferably up to 50 carbon atoms, more preferably up to 24 carbon atoms, and most preferably up to 12 carbon atoms. Halophosphines (e.g., hydrocarbyl phosphorus tetrahalides, dihydrocarbyl phosphorus trihalides, and trihydrocarbyl phosphorus dihalides), and halophosphines (monohalophosphines and dihalophosphines) can also be used.

[0044] In one embodiment, the fluid relatively high molecular weight succinimide dispersants herein comprise at least a polyisobutenyl moiety having a number average molecular weight of at least about 2000, in another embodiment from about 2000 to about 3000, or in yet another embodiment from about 2000 to about 2300, and having from about 0.5 to about 1 weight percent nitrogen, from about 0.05 to about 0.25 weight percent boron, and from about 0.20 to about 0.45 weight percent phosphorous, or in yet another embodiment, at least a polyisobutenyl moiety having a number average molecular weight of 2000 to 2300, and having from about 0.60 to about 0.90 weight percent nitrogen, from about 0.10 to about 0.20 weight percent boron, and from about 0.25 to about 0.40 weight percent phosphorous.

[0045] In some embodiments, the relatively high molecular weight dispersants described herein may comprise from about 40 to about 70 weight percent of the additive concentrate. In some embodiments, the relatively high molecular weight succinimide dispersants described herein comprise at least a polyisobutenyl portion having a number average molecular weight of from about 2000 to about 2300, have from about 0.6 to about 0.9 weight percent nitrogen, from about 0.10 to about 0.20 weight percent boron, and from about 0.25 to about 0.40 weight percent phosphorus, and may comprise from about 40 to about 70% of the additive concentrate. In some embodiments, the relatively high molecular weight succinimide dispersants described herein comprise at least a polyisobutenyl portion having a number average molecular weight of from about 2000 to about 2300, and deliver from about 3000 to about 5400 ppm nitrogen, from about 600 to about 1000 ppm boron, and from about 1400 to about 2450 ppm phosphorus to the additive concentrate.

[0046] In some embodiments, the relatively high molecular weight dispersants described herein comprise from about 2.0 to about 4.0% of an electric motor lubricating fluid and deliver from about 150 to about 300 ppm nitrogen, from about 70 to about 140 ppm phosphorus, and from about 30 to about 60 ppm boron. As shown in the examples below, when such succinimide dispersants are combined with other fluid components, particularly selected amounts of sulfur, boron, nitrogen, and / or phosphorus, the lubricants achieve good wear and conductivity performance, as well as oxidation stability.

[0047] Amine salts of phosphate esters: The electric motor lubricating fluids herein also include a first phosphorus providing additive in an amount that provides from about 40 to about 70 ppm phosphorus from the amine salt to the fluid. In some approaches or embodiments, the first phosphorus providing additive is in the form of an amine salt of a phosphorus ester. In some approaches, the amine salt of a phosphorus ester can include one or more monoalkyl phosphate esters, dialkyl phosphate esters, and / or mixtures thereof, where the alkyl groups can be linear, branched, or cyclic. The fluids herein may also include other compounds that provide phosphorus, but in some embodiments, the amine salt of a phosphorus ester herein provides from about 20 to about 40 weight percent of the total phosphorus in the electric motor lubricating fluid.

[0048] In an approach or embodiment, an exemplary amine salt of a phosphate ester may be represented by formula I:

[0049] [ka] R3 and R4 of formula I can be independently hydrogen or a linear, branched, or cyclic hydrocarbyl group, m of formula I is an integer from 0 to 1, p of formula I is an integer from 1 to 2, and m+p is equal to 2, R5, R6, R7, and R8 of formula I can be independently hydrogen or a hydrocarbyl group, and at least one of R5-R8 of formula I is a hydrocarbyl group. Examples of suitable alkyl or hydrocarbyl groups for R3 and / or R4 of formula I include linear or branched alkyl groups such as, but not limited to, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and / or decyl groups. In yet another exemplary approach, R3 and R4 in formula I can be cyclic hydrocarbyl groups, examples of which include cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclopentyl, dimethylcyclopentyl, methylethylcyclopentyl, diethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl, dimethylcycloheptyl, methylethyl-cycloheptyl, and / or diethylcycloheptyl. In some approaches or embodiments, suitable amine salts of phosphoric acid esters are mixtures of monoalkyl and dialkyl phosphoric acid esters. The monoalkyl and dialkyl groups can be linear, branched, or cyclic, as described above.

[0050] The amine salt of the phosphoric acid ester may be derived from a primary, secondary, or tertiary amine, or a mixture thereof. Exemplary amines suitable for the salt may be aliphatic, cyclic, aromatic, or non-aromatic, but are generally aliphatic amines. Examples of suitable primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, bis-(2-ethylhexyl)amine, octylamine, and dodecylamine, as well as fatty amines such as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, or oleylamine. Examples of suitable secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine, N-methyl-1-amino-cyclohexane, and / or ethylamylamine. The secondary amines may also be cyclic amines such as piperidine, piperazine, and morpholine. Examples of suitable tertiary amines may include tri-n-butylamine, tri-n-octylamine, tri-decylamine, tri-laurylamine, tri-hexadecylamine, and / or dimethyl-oleylamine.

[0051] In some procedures, the amine of formula I above is 10 ~C 20 At least one of the R, R, R, or R groups of formula I can be an alkyl group, and in other approaches or embodiments, at least two of the R, R, R, or R groups of formula I can be independently selected from the group consisting of 10 ~C 20 In some embodiments, at least two of the R, R, R, or R groups of formula I are independently C 12 ~C 14 It is an alkyl group.

[0052] The amine salt of a phosphoric acid ester can be prepared by reacting a suitable phosphorus compound with an amine to form the amine salt of a phosphoric acid ester. In one embodiment, the amine salt of a phosphoric acid ester can be of formula I, where R3 and R4 can be independently C6 or hydrogen, m is an integer from 0 to 1, p is an integer from 1 to 2, m+p is equal to 2, R5, R6, R7, and R8 are independently hydrogen or C6. 12 ~C 14 At least one of R5 to R8 may be a hydrocarbyl group represented by the formula: 12 ~C 14 is a hydrocarbyl group of the formula:

[0053] In some embodiments, the amine salt of a phosphoric acid ester may be present in the additive concentrate in an amount of from 2 wt% to about 3 wt%, or from about 2.2 wt% to about 2.5 wt%. The amine salt of a phosphoric acid ester can deliver from about 1000 to about 1500 ppm phosphorus, or from about 1000 to about 1250 ppm phosphorus to the additive concentrate.

[0054] In one embodiment, the amine salt of a phosphoric acid ester may be present in the electric motor lubricating fluids herein in an amount of at least about 0.1% to about 0.3% by weight of the lubricating composition, or from about 0.1 to about 0.25% by weight of the lubricating composition. The amine salt of a phosphoric acid ester may deliver from about 50 to about 150 ppm of phosphorus, or from about 50 to about 125 ppm of phosphorus to the lubricating composition.

[0055] Ashless Dialkyldithiophosphates: In one approach or embodiment, the electric motor lubricating fluids herein may also include a second phosphorus-providing additive in the form of an acid thiophosphate or a thiophosphate ester. In one approach or embodiment, this second phosphorus-providing additive may be an ashless, amine-free dialkyldithiophosphate ester or a sulfur-containing phosphate ester.

[0056] The acid thiophosphate, thiophosphate ester, or sulfur-containing phosphate ester of the second phosphorus compound may have one or more sulfur-phosphorus bonds. In one embodiment, the sulfur-containing phosphate ester may be an acid thiophosphate, a thiophosphate ester, a thiophosphoric acid, or a salt thereof. The thiophosphate ester may be a dithiophosphate ester. In some more specific approaches, the acid thiophosphate or thiophosphate ester may have the structure of formula II or a salt thereof:

[0057] [ka] In the formula, R4 and R5 in formula II are each independently a linear or branched C1-C 10 R7 in formula II is a hydrocarbyl group, 10 Linear or branched carboxyl group, or C1-C 10 Preferably, R4 and R5 of formula II are each a C3-C8 straight chain or branched alkyl alkanoate group, and R7 of formula II is derived from 2-methyl propanoic acid, such that the phosphorus product (or a salt thereof) has the structure of formula II:

[0058] [ka] wherein R4 and R5 in the above formula II are independently a C3-C8 linear or branched alkyl group (preferably a branched C4 group), and R6 in the above formula II is -H or -CH3. In some approaches or embodiments, the second phosphorus product is preferably 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methyl-propanoic acid.

[0059] In some approaches, the oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate is made by a process comprising: (a) reacting an organic hydroxy compound with phosphorus pentasulfide (in some forms, a monomer or a dimer thereof) to form a reaction product; and further reacting the reaction product with an unsaturated carboxylic acid to form the oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate.

[0060] Suitable organic hydroxy compounds may include normal straight chain alcohols, branched chain alcohols, hydroxyaryl compounds such as phenol and naphthol, substituted arylhydroxy compounds such as diamylphenol, or any other hydroxyorganic material whose hydroxy group reacts with phosphorus pentasulfide. In one approach, the starting alcohol is a saturated alcohol or a substituted arylhydroxy compound such as an arylhydroxy compound substituted with a saturated alkyl group. In some approaches, the organic hydroxy compound is a C1-C hydroxyalkyl alcohol such as one or more of methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, phenol, naphthol, amyl alcohol, hexyl alcohol, iso-hexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol, octadecyl alcohol, 2-ethylhexyl alcohol, 4-methyl-2-pentyl alcohol, phenyl alcohol, butylphenyl alcohol, cyclohexyl alcohol, methylcyclopentyl alcohol, propenyl alcohol, butenyl alcohol, or combinations thereof. 10 (Alternatively, it may be a C1-C6 straight chain or branched alcohol, a hydroxyaryl compound, or mixtures thereof. Preferred organic hydroxy compounds herein include C1-C4 alcohols such as ethyl alcohol, propyl alcohol, or isopropyl alcohol, and most preferably, the organic hydroxy compound is isobutyl alcohol.

[0061] Unsaturated carboxylic acids suitable for forming the oil-soluble phosphorus anti-wear additive of the present disclosure can include a wide variety of unsaturated carboxylic acids or fatty acids. Preferred unsaturated carboxylic acids include C1-C acrylic acid, methacrylic acid, 2-ethylacrylic acid, or combinations thereof. 20 Unsaturated fatty acids may be included, most preferably methacrylic acid. (As used herein, (meth)acrylic acid refers to either acrylic acid or methacrylic acid.)

[0062] In some embodiments, the second phosphorus providing additive is an acid thiophosphate or thiophosphate ester present in the additive concentrate in an amount to provide from 800 ppm to 1300 ppm of phosphorus and less than 2800 ppm of sulfur to the additive concentrate. In another embodiment, the second phosphorus providing additive is an acid thiophosphate or thiophosphate ester present in the additive concentrate in an amount to provide from 900 ppm to 1200 ppm of phosphorus and less than 2500 ppm of sulfur to the additive concentrate. In one approach, the additive concentrate contains from about 80% to about 1.75% by weight of the ashless dialkyldithiophosphate compound, and in other approaches, from about 0.9% to about 1.40% by weight, from about 1.0% to about 1.3% by weight.

[0063] In one approach or embodiment, the electric motor lubricating fluids herein may also include a second phosphorus providing additive in the form of an ashless dialkyldithiophosphate compound in an amount to provide the fluid with from about 40 to about 70 ppm phosphorus and less than 160 ppm sulfur. In some embodiments, the electric motor lubricating fluids herein may include a second phosphorus providing additive in the form of an ashless dialkyldithiophosphate compound in an amount to provide the fluid with from about 50 to about 65 ppm total phosphorus and less than 140 ppm sulfur. In one approach or embodiment, the electric motor lubricating fluids herein include from about 0.03 wt % to about 0.1 wt % of the ashless dialkyldithiophosphate compound, and in another approach, from about 0.04 wt % to about 0.08 wt %.

[0064] Sulfur Providing Additive: The electric motor lubricating fluid includes a sulfur-providing additive. In the manner or embodiment herein, the sulfur-providing additive may be one or more thiadiazole compounds or hydrocarbyl-substituted derivatives thereof in an amount that provides sulfur to the lubricating fluid herein, but not exceeding about 950 ppm sulfur. In another manner, the sulfur-providing compound may be a mixture of thiadiazole compounds or hydrocarbyl-substituted derivatives thereof. Examples of thiadiazole compounds that may be used include, but are not limited to, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazole, 2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazole, 2,5-bis(hydrocarbylthio)-1,3,4-thiadiazole, or 2,5-bis(hydrocarbyldithio)-1,3,4-thiadiazole. 1,3,4-thiadiazole is generally synthesized from hydrazine and carbon disulfide by known methods. See, for example, U.S. Patent No. 2,765,289, U.S. Patent No. 2,749,311, U.S. Patent No. 2,760,933, U.S. Patent No. 2,850,453, U.S. Patent No. 2,910,439, U.S. Patent No. 3,663,561, U.S. Patent No. 3,862,798, and U.S. Patent No. 3,840,549.

[0065] In the method, the thiadiazole or derivative thereof includes one or more compounds having the structure of formula III:

[0066] [ka] wherein each R1 in formula III is independently hydrogen or sulfur, each R2 in formula III is independently an alkyl group, and n is an integer of 0 or 1, where when R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and when R1 is sulfur, the integer n of the adjacent R2 moiety is 1, provided that at least one R1 is sulfur. In another approach, the thiadiazole additive is a blend of compounds of formula IIIa and formula IIIb shown below:

[0067] [ka] In formula IIIa, each integer n is 1, each R1 is sulfur, and each R2 is a C5-C 15 Alkyl groups, preferably C8 to C 12 is an alkyl group,

[0068] [ka] In formula IIIb, one integer n is 1 and the associated R2 group is a C5-C 15 Alkyl group (preferably C8 to C 12 alkyl group), the other integer n is 0, and both R1 are sulfur. In some embodiments, the sulfur-providing additive comprises a blend of formulas IIIa and IIIb, where formula Iva is the majority of the blend, and in other approaches, the blend of IIIa and IIIb is about 75 to about 90% by weight IIIa and about 10 to about 25% by weight IIIb (or other ranges therein). In another approach, the sulfur-providing additive is a 2,5 dimercapto 1,3,4 thiadiazole, including a blend of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole (such as about 75 to about 90%) and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole (such as about 10 to about 25%).

[0069] The thiadiazole compound or hydrocarbyl-substituted derivatives thereof are present in the electric motor lubricating fluids herein in an amount to deliver up to about 950 ppm sulfur, up to about 925 ppm sulfur, or up to about 900 ppm sulfur, in other embodiments at least about 700 ppm sulfur, or at least about 800 ppm sulfur (or other ranges therein). In one embodiment, the thiadiazole compound is 2,5-dimercapto-1,3,4-thiadiazole, and the thiadiazole compound or hydrocarbyl-substituted derivatives thereof are present in the lubricating and cooling fluids in an amount to deliver from about 700 to about 950 ppm sulfur, or from about 750 to about 900 ppm sulfur (or other ranges therein).

[0070] Base oil: The electric motor lubricating fluids herein include one or more base oils having a lubricating viscosity. Base oils suitable for use in formulating electric motor lubricating fluids for use in electric and / or hybrid vehicles according to the present disclosure may be selected from any suitable synthetic or natural oil or mixtures thereof having a suitable lubricating viscosity. Natural oils may include animal oils, and vegetable oils (e.g., castor oil, lard oil), as well as mineral oils such as liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic, or mixed paraffinic-naphthenic types. Oils derived from coal or shale may also be suitable. Additionally, oils derived from gas-to-liquid processes are also suitable. The base oils may have a kinematic viscosity of about 2 to about 15 cSt at 100° C. as measured by ASTM D2270-10.

[0071] The base oil used in the invention described herein may be a single base oil or a mixture of two or more base oils. One or more base oils may be selected from any of the base oils in Groups III or IV as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. Such base oil groups are shown in Table 1 as follows:

[0072] [Table 1]

[0073] In one variant, the base oil may be selected from an API Group III base oil, or an API Group IV base oil, or a mixture of these base oils. Alternatively, the base oil may be a mixture of two or more of API Group III base oils, or two or more of API Group IV base oils.

[0074] API Group III base oils may include oils derived from Fischer-Tropsch synthetic hydrocarbons. Fischer-Tropsch synthetic hydrocarbons are made from synthesis gas containing H2 and CO using a Fischer-Tropsch catalyst. Such hydrocarbons typically require further processing to be useful as base oils. These types of oils are commonly referred to as gas-to-liquids (GTL). For example, the hydrocarbons may be hydroisomerized using the processes disclosed in U.S. Pat. Nos. 6,103,099 or 6,180,575, hydrocracked or hydroisomerized using the processes disclosed in U.S. Pat. Nos. 4,943,672 or 6,096,940, dewaxed using the methods disclosed in U.S. Pat. No. 5,882,505, or hydroisomerized and dewaxed using the processes disclosed in U.S. Pat. Nos. 6,013,171, 6,080,301, or 6,165,949.

[0075] PAOs, which are API Group IV base oils, are typically derived from monomers having 4 to 30, or 4 to 20, or 6 to 16 carbon atoms. Examples of PAOs that may be used in the present invention include those derived from octene, decene, mixtures thereof, and the like. The PAOs may have a kinematic viscosity at 100° C., as measured by ASTM D2270-10, of 2 to 15, or 3 to 12, or 4 to 8 cSt. Examples of PAOs include 4 cSt PAOs at 100° C., 6 cSt PAOs at 100° C., and mixtures thereof.

[0076] 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, gears, and clutch. Thus, the base oil may be present in the lubricating and cooling fluid in an amount greater than about 80% by weight, based on the total weight of the lubricating and cooling fluid. In some embodiments, the base oil may be present in the lubricating and cooling fluid in an amount greater than about 85% by weight, based on the total weight of the lubricating and cooling fluid.

[0077] Other Additives The electric motor lubricating fluids described herein may contain, in addition to the components described above, conventional additives of the type used in transmission fluid compositions, including, but not limited to, antioxidants, viscosity modifiers, phosphorus-containing components, detergents, corrosion inhibitors, rust inhibitors, antifoam agents, demulsifiers, pour point depressants, seal swell agents, as well as additional dispersants, additional friction modifiers, and additional sulfur-containing components.

[0078] Antioxidants: In some embodiments, the electric motor lubricating fluid contains one or more antioxidants. Suitable antioxidants include phenolic antioxidants, aromatic amine antioxidants, sulfur-containing antioxidants, and organic phosphites, among others.

[0079] Examples of phenolic antioxidants include 2,6-di-tert-butylphenol, liquid mixtures of tributylated 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, and 4,4'-thiobis(2-methyl-6-tert-butylphenol), N,N'-di-sec-butyl-phenylenediamine, 4-isopropylaminodiphenylamine, phenyl-alpha-naphthylamine, phenyl-alpha-naphthylamine, and ring alkylated diphenylamines. Examples include sterically hindered tertiary butylated phenols, bisphenols, and cinnamic acid derivatives, and combinations thereof.

[0080] Aromatic amine antioxidants include those having the following formula:

[0081] [ka] (wherein R' and R'' each independently represent a substituted or unsubstituted aryl group having 6 to 30 carbon atoms). Examples of the substituent of the aryl group include an aliphatic hydrocarbon group such as an alkyl group having 1 to 30 carbon atoms, a hydroxy group, a halogen radical, a carboxylic acid or ester group, or a nitro group.

[0082] The aryl groups are preferably substituted or unsubstituted phenyl or naphthyl, in particular where one or both of the aryl groups are substituted with at least one alkyl having from 4 to 30 carbon atoms, preferably from 4 to 18 carbon atoms, most preferably from 4 to 9 carbon atoms. It is preferred that one or both of the aryl groups are substituted, for example mono-alkylated diphenylamines, di-alkylated diphenylamines, or mixtures of mono- and di-alkylated diphenylamines.

[0083] Examples of diarylamines that may be used include, but are not limited to, diphenylamine; the various alkylated diphenylamines, 3-hydroxydiphenylamine, N-phenyl-1,2-phenylenediamine, N-phenyl-1,4-phenylenediamine, monobutyldiphenyl-amine, dibutyldiphenylamine, monooctyldiphenylamine, dioctyldiphenylamine, monononyldiphenylamine, dinonyldiphenylamine, monotetradecyldiphenylamine, ditetradecyldiphenylamine, phenyl-alpha-naphthylamine, monooctylphenyl-alpha-naphthylamine, phenyl-beta-naphthylamine, monoheptyldiphenylamine, diheptyl-diphenylamine, p-oriented styrenated diphenylamines, mixed butyloctyldi-phenylamines, and mixed octylstyryldiphenylamines.

[0084] 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., olefins having an average molecular weight of 168 to 351 g / mol, are preferred. Examples of olefins that may be used include alpha-olefins, isomerized alpha-olefins, branched olefins, cyclic olefins, and combinations thereof.

[0085] Alpha-olefins include any C4-C 25 Examples of suitable isomers include, but are not limited to, alpha-olefins. The alpha-olefins may be isomerized before or during the sulfurization reaction. Structural and / or conformational isomers of alpha-olefins containing internal double bonds and / or branching may also be used. For example, isobutylene is the branched olefin counterpart of the alpha-olefin 1-butene.

[0086] Sulfur sources that may be used in the sulfurization reaction of olefins include elemental sulfur, sulfur monochloride, sulfur dichloride, sodium sulfide, sodium polysulfide, and mixtures thereof added together at different stages of the sulfurization process.

[0087] Unsaturated oils may also be sulfurized and used as antioxidants due to their unsaturation. Examples of oils or fats that may be used include corn oil, canola oil, cottonseed oil, grapeseed oil, olive oil, palm oil, peanut oil, coconut oil, rapeseed oil, safflower seed oil, sesame seed oil, soybean oil, sunflower seed oil, tallow, and combinations thereof.

[0088] The total amount of antioxidant in the lubricating and cooling fluids herein may be present in an amount to deliver up to about 200 ppm nitrogen, or up to about 150 ppm nitrogen, or from about 100 to about 150 ppm nitrogen.

[0089] Friction modifiers: In some embodiments, the electric motor lubricating fluid contains additional friction modifiers other than those contained in the friction modifier system described above.Suitable additional friction modifiers can include metal-containing and metal-free friction modifiers, and suitable friction modifiers 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, alkanolamides, 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, and one or more aliphatic or aromatic carboxylic acids.

[0090] Suitable friction modifiers may contain hydrocarbyl groups selected from linear, branched, or aromatic hydrocarbyl groups, or mixtures thereof, and such hydrocarbyl groups may be saturated or unsaturated. The hydrocarbyl groups may be composed of carbon and hydrogen or heteroatoms such as sulfur or oxygen. The hydrocarbyl groups may range from 12 to 25 carbon atoms. In some embodiments, the friction modifier may be a long chain fatty acid ester. In other embodiments, the long chain fatty acid ester may be a mono-ester, or a di-ester, or a (tri)glyceride. The friction modifier may be a long chain fatty amide, a long chain fatty ester, a long chain fatty epoxide derivative, or a long chain imidazoline.

[0091] Other suitable friction modifiers may include organic, ashless (metal-free), nitrogen-free mechanical friction modifiers. Such friction modifiers include esters formed by reacting carboxylic acids and anhydrides with alkanols, and generally may contain polar end groups (e.g., carboxyl or hydroxyl) covalently bonded to an oleophilic hydrocarbon chain. An example of an organic ashless nitrogen-free friction modifier is commonly known as glycerol monooleate (GMO), which may contain mono-, di-, and tri-esters of oleic acid. Other suitable friction modifiers are described in U.S. Pat. No. 6,723,685.

[0092] Aminic friction modifiers may include amines or polyamines. Such compounds may have hydrocarbyl groups that are either saturated or unsaturated, linear, or a mixture thereof, and may contain from 12 to 25 carbon atoms. Further examples of suitable friction modifiers include alkoxylated amines and alkoxylated ether amines. Such compounds may have hydrocarbyl groups that are either saturated or unsaturated, linear, or a mixture thereof. They may contain from about 12 to about 25 carbon atoms. Examples include ethoxylated amines and ethoxylated ether amines.

[0093] The amines and amides may be used as such or in the form of adducts or reaction products with boron compounds such as boron oxides, boron halides, metaborates, boric acid or mono-, di-, or tri-alkylborates. Other suitable friction modifiers are described in U.S. Pat. No. 6,300,291.

[0094] When additional friction modifiers contain nitrogen, such additional friction modifiers may be present in the lubricating and cooling fluids in any amount so long as performance requirements are not compromised.

[0095] Detergent: Metal detergents that may be included in the electric motor lubrication fluids described herein generally comprise a polar head and a long hydrophobic tail, the polar head consisting of a metal salt of an acidic organic compound. The salts may contain substantially stoichiometric amounts of metal, in which case they are usually 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 base may be included by reacting an excess of a metal compound, such as an oxide or hydroxide, with an acid gas, such as carbon dioxide. The resulting overbased detergent comprises micelles of neutralized detergent surrounding a core of inorganic metal base (e.g., hydrated carbonate). Such overbased detergents may have a TBN of about 150 or greater, e.g., about 150 to about 450 or greater.

[0096] Detergents that may be suitable for use in this embodiment include oil-soluble overbased, low based and neutral sulfonates, phenates, sulfurized phenates, and salicylates of metals, particularly alkali or alkaline earth metals, such as sodium, potassium, lithium, calcium, and magnesium. More than one metal may be present, such as both calcium and magnesium. Mixtures of calcium and / or magnesium with sodium may also be suitable. Suitable metal detergents may be overbased calcium or magnesium sulfonates with a TBN of 150-450 TBN, overbased calcium or magnesium phenates or sulfurized phenates with a TBN of 150-300 TBN, and overbased calcium or magnesium salicylates with a TBN of 130-350. Mixtures of such salts may also be used.

[0097] The metal-containing detergent may be present in the lubricating and cooling fluid in an amount sufficient to improve the rust inhibitor performance of the fluid. The metal-containing detergent may be present in the fluid in an amount sufficient to provide up to 90 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 detergent may be present in an amount sufficient to provide from about 20 to about 50 ppm of alkali and / or alkaline earth metals. In another embodiment, the metal-containing detergent may be present in an amount sufficient to provide from about 30 to about 40 ppm of alkali and / or alkaline earth metals.

[0098] In one approach, the preferred detergent may be a neutral to low based sulfonate, and in some approaches, a calcium sulfonate. A suitable detergent may be a calcium sulfonate having a TBN of 50 or less (e.g., about 25 to about 30) and providing about 50 ppm or less of calcium to the lubricant. In other approaches, the detergent may provide about 25 to about 40 ppm of calcium, about 30 to about 40 ppm of calcium, or about 30 to about 38 ppm of calcium to the finished electric motor lubricating fluid or composition. With respect to additive concentrates, the detergent may provide greater than about 950 ppm of calcium to the additive concentrate, or about 500 to about 950 ppm of calcium, about 550 to about 900 ppm of calcium, about 600 to about 800 ppm of calcium, or about 600 to about 700 ppm of calcium to the additive concentrate.

[0099] Corrosion Inhibitors: Rust or corrosion inhibitors may also be included in the electric motor lubricating fluids described herein. Such materials include mono- and polycarboxylic acids. Examples of suitable mono-carboxylic acids are octanoic acid, decanoic acid, and dodecanoic acid. Suitable polycarboxylic acids include dimer and trimer acids made from acids such as tall oil fatty acids, oleic acid, and linoleic acid.

[0100] Another useful type of rust inhibitor may be, for example, alkenyl succinic acid and alkenyl succinic anhydride corrosion inhibitors, such as tetrapropenyl succinic acid, tetrapropenyl succinic anhydride, tetradecenyl succinic acid, tetradecenyl succinic anhydride, hexadecenyl succinic acid, hexadecenyl succinic anhydride. Half esters of alkenyl succinic acids having 8 to 24 carbon atoms in the alkenyl group with alcohols such as polyglycols are also useful. Other suitable rust or corrosion inhibitors include ether amines, acid phosphoric acids, amines, polyethoxylated compounds such as ethoxylated amines, ethoxylated phenols, ethoxylated alcohols, imidazolines, aminosuccinic acids or derivatives thereof, and the like. Mixtures of such rust or corrosion inhibitors may be used. The total amount of corrosion inhibitor, if present, in the lubricating compositions described herein can be up to 2.0 wt. %, or in the range of 0.01 to 1.0 wt. %, based on the total weight of the lubricating composition.

[0101] Viscosity modifiers: The electric motor lubricating fluid may optionally contain one or more viscosity modifiers. Suitable viscosity modifiers may include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutene, hydrogenated styrene-isoprene polymers, styrene / maleic acid ester copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkylstyrenes, hydrogenated alkenylaryl conjugated diene copolymers, or mixtures thereof. Viscosity modifiers may include star polymers, suitable examples of which are described in U.S. Patent Application Publication No. 2012 / 0101017(A1).

[0102] The electric motor lubricating fluids described herein may also optionally include one or more dispersant viscosity modifiers in addition to or in place of the viscosity modifier. Suitable dispersant viscosity modifiers may include functionalized polyolefins, such as ethylene-propylene copolymers functionalized with the reaction product of an acylating agent (such as maleic anhydride) with an amine, amine-functionalized polymethacrylates, or esterified maleic anhydride-styrene copolymers reacted with amines.

[0103] The total amount of viscosity modifier and / or dispersant viscosity modifier, if 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.

[0104] Demulsifiers: Demulsifiers include trialkyl phosphates and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, including polyethylene oxide, polypropylene oxide, and (ethylene oxide-propylene oxide) polymers, or mixtures thereof. When present, the amount of demulsifier in the lubricating and cooling fluids 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.

[0105] Antifoaming agents: Antifoaming agents used to reduce or prevent the formation of stable foam include silicones, polyacrylates, or organic polymers. Antifoaming agents that may be useful in the disclosed inventive compositions include polysiloxanes, copolymers of ethyl acrylate and 2-ethylhexyl acrylate, and, optionally, vinyl acetate. If present, the amount of antifoaming agent in the lubricating and cooling fluid may be up to about 0.1 wt.%, or up to about 0.05 wt.%, or less than about 0.04 wt.%, based on the total weight of the lubricating and cooling fluid.

[0106] Pour Point Depressants: Electric motor lubricating fluids may optionally contain one or more pour point depressants. Suitable pour point depressants may include esters of maleic anhydride-styrene, polymethacrylates, polymethyl methacrylates, polyacrylates or polyacrylamides, or mixtures thereof. If present, pour point depressants may be present in an amount of about 0.001% to about 0.04% by weight, based on the total weight of the lubricant.

[0107] In general, the lubricating and cooling fluids described herein may contain additive components within the ranges listed in Table 2.

[0108] [Table 2]

[0109] The percentages of each component above represent the weight percent of each component based on the total weight of the lubricating and cooling fluid containing the listed components. The additives used in formulating the compositions described herein may be blended into the base oil individually or in various partial combinations. However, it may be preferred to blend all of the components simultaneously using an additive concentrate (i.e., additives plus a diluent such as a hydrocarbon solvent). The use of an additive concentrate takes advantage of the mutual compatibility afforded by the combination of components when in the form of an additive concentrate. The use of a concentrate also reduces mixing time and the possibility of mixing errors.

[0110] As noted above, additive concentrates containing relatively high molecular weight succinimide dispersants, amine salts of phosphoric acid esters, ashless dialkyldithiophosphates, and thiadiazoles or derivatives thereof have viscosities much higher than those commonly used in vehicle lubricants having viscosities at kV100°C of about 4.5 cSt or less, about 3.5 cSt or less, or about 3.0 cSt or less. In some approaches, additive concentrates herein of such components have kV100°C of about 15 to about 80 cSt, but when used in finished fluids having the elemental relationships noted, the electric motor lubricating fluids herein still have finished kV100°C of about 4.5 cSt or less, about 3.5 cSt or less, or about 3.0 cSt or less, with improved wear, conductivity, and oxidation stability. In some embodiments, the ratio of kV100°C of the additive concentrate to the kV100°C of the finished fluid is about 5:1 to about 30:1. Any embodiment of the electric motor lubricating fluid herein exhibits only a slight viscosity change after aging, such as a change of about 0.10 cSt or less (e.g., 0.01 to 0.1 cSt or 0.04 to 0.08 cSt) after the fluid is aged for at least 192 hours at 170° C. to 180° C. according to CEC L-48-A. The electric motor lubricating fluid herein also achieves a failure load stage of at least 8 in the FZG A10 / 16.6R / 90 scuffing test of CEC L-84-02. Finally, the electric motor lubricating fluid herein also has an electrical conductivity of about 60 nS / M or less (e.g., about 20 to about 60 nS / M) as measured by a modified conductivity test according to ASTM D2624-15 using the electric motor lubricating fluid, measured at 20 Hz and about 100° C. using a Fullcon Epsilon tester or equivalent. It was surprising that such a low viscosity fluid, with low conductivity and high oxidative stability, could achieve such acceptable performance in the FZG A10 / 16.6R / 90 scuffing test of CEC L-84-02. EXAMPLES

[0111] A better understanding of the present disclosure and its many advantages can be made clear with the following examples. The following examples are illustrative and are not intended to be limiting in scope or spirit. Those skilled in the art will readily understand that variations of the components, methods, steps, and devices described in these examples can be used. Unless otherwise stated or apparent from the context of the following examples and discussion throughout this disclosure, all percentages, ratios, and parts described in this disclosure are by weight.

[0112] To demonstrate how high molecular weight dispersants can be used in low viscosity fluids to achieve acceptable wear and conductivity, the system herein evaluated the wear, oxidative stability, and conductivity of fluids in very low viscosity fluids having kV100°C of about 4.5 cSt or less, about 3.5 cSt or less, about 3.0 cSt or less, or about 2.9 cSt or less, comparing fluids having various elemental relationships of nitrogen, boron, sulfur, and / or phosphorus. The formulations were evaluated for FZG scuffing, oxidative viscosity stability, and electrical conductivity.

[0113] FZG scuffing was used to evaluate the scuffing load capacity of lubricants and was performed according to the A10 / 16.6R / 90 test of CEC L-84-02. Results are reported at the failure load stage, with better results being obtained for samples with higher failure load stages.

[0114] Oxidative viscosity stability is used to evaluate the difference between the initial viscosity and the final viscosity after aging the fluid for 192 hours at operating conditions of 170°C to 180°C in accordance with CEC L-48-A-00, aging being carried out at 170°C for the fluids in this example. Lower values ​​indicate improved performance. Thus, fluids with high oxidative stability will show only a small change in viscosity measured before and after aging.

[0115] It is beneficial for electric motor fluids to exhibit low conductivity. Fluid conductivity was measured according to a modified version of ASTM D2624-15 (testing lubricants, not fuels) at 1.5V, 20Hz, and 100°C using a Flucon Epsilon+.

[0116] The inventive and comparative formulations tested in Table 3 below all contained various amounts of sulfurized components, phosphorus additives, detergents, and dispersants, as shown in Table 3. Each fluid further contained the same antioxidant, antifoam, and process oil. The antioxidant and antifoam were added to each fluid at the same treatment rate. The inventive and comparative formulations were tested in the same base oil to obtain finished fluids having kinematic viscosities at 100°C as shown in the table below. The inventive formulations contain similar additives as the comparative formulations, but the delivery of sulfur, phosphorus, and dispersants was balanced differently to achieve surprisingly improved wear, oxidation stability, and lubricant conductivity. The details of these components are described below: Sulfur component (S-1): 2,5-dimercapto-1,3,4-thiadiazole and / or its derivatives containing approximately 35% by weight of sulfur, which was a 75:25 to 85:15 mixture of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole. Dispersant (Disp-1): A phosphated and borated succinimide dispersant made from 950Mn polyisobutylene, maleic anhydride, a mixture of polyalkylene polyamines having an average of 6.5 nitrogen atoms per molecule, phosphoric acid, and boric acid. This dispersant contained about 0.76% by weight phosphorus, about 0.35% by weight boron, and about 1.75% by weight nitrogen. Dispersant 2 (Disp-2): A phosphated and borated succinimide dispersant made from 2100Mn polyisobutylene, maleic anhydride, a mixture of polyalkylene polyamines having an average of 6.5 nitrogen atoms per molecule, phosphoric acid, and boric acid. The dispersant had approximately 0.77% by weight nitrogen, about 0.15% by weight boron, and about 0.35% by weight phosphorus. Phosphorus additive 1 (P-1): Dihexyl phosphate and monohexyl phosphate, and C 12 ~C 14 The amine salt of a phosphorus ester containing a mixture of di- and / or trialkylated amines having alkyl groups of about 2.5% by weight nitrogen and about 4.9% by weight phosphorus. Phosphorus additive 2 (P-2): Ashless dialkyl dithiophosphate containing at least 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methyl-propanoic acid Detergent Additive 1 (Det-1): A neutral calcium sulfonate having a TBN of about 25 to about 30 and about 2.6% by weight calcium.

[0117] All fluids tested herein contained the same blend of Group III and Group IV base oils. As shown in the table below, all inventive examples showed improved wear performance, conductivity performance, and oxidation stability compared to comparative examples that delivered too little or too much phosphorus and contained relatively low molecular weight dispersant additives. All fluids were considered low viscosity fluids, having a kV100°C (ASTM D445) of about 4.5 cSt or less.

[0118] [Table 3] -kV100℃ was measured in accordance with ASTM D445.

[0119] [Table 4]

[0120] [Table 5] ** CEC L-84-022(A10 / 16.6R / 90) *** Difference between initial viscosity and final viscosity after aging according to CEC L-48-A ****ASTM D2624-15 (20Hz, 100℃) performed on a Fullcon Epsilon or equivalent tester

[0121] Although the lubricating compositions of the present disclosure have been described with reference to the detailed description and abstract herein, it should be understood that the foregoing description is intended to illustrate, and not to limit, the scope of the present disclosure, which is defined by the appended claims. Other aspects, advantages, and modifications are within the scope of the claims. It is intended that the specification and examples be considered as exemplary only, with the true scope of the present disclosure being indicated by the following claims.

[0122] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. As used throughout the specification and claims, "a" and / or "an" may refer to one or more than one. Unless otherwise indicated, all numbers expressing properties such as amounts of ingredients, molecular weights, percentages, ratios, reaction conditions, and the like, used herein, whether or not the term "about" is present, should be understood in all instances as being modified by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed at least in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0123] It is understood that each component, compound, substituent, or parameter disclosed herein should be construed as disclosed for use alone or in combination with one or more of any and all other components, compounds, substituents, or parameters disclosed herein.

[0124] It is further to be understood that each range disclosed herein should be construed as a disclosure of each particular value within the disclosed range having the same number of significant digits, thus a range of 1 to 4 should be construed as an explicit disclosure of any range of values ​​such as 1, 2, 3, and 4, as well as 1 to 4, 1 to 3, 1 to 2, 2 to 4, 2 to 3, etc.

[0125] It is further to be understood that each lower limit of each range disclosed herein should be construed as disclosed in combination with each upper limit of each range and each specific value within each range for the same component, compound, substituent, or parameter. Thus, the present disclosure should be construed as a disclosure of all ranges derived by combining each lower limit of each range with each upper limit of each range or with each specific value within each range, or by combining each upper limit of each range with each specific value within each range.

[0126] Furthermore, a specific amount / value of a component, compound, substituent, or parameter disclosed in the description or examples should be construed as a disclosure of either a lower or upper limit of a range and therefore can be combined with any other lower or upper limit of a range or specific amount / value for the same component, compound, substituent, or parameter disclosed elsewhere in this application to form a range for that component, compound, substituent, or parameter.

Claims

1. 1. An electric motor lubricating fluid for an electric vehicle or hybrid electric vehicle, comprising: one or more base oils of lubricating viscosity; a succinimide dispersant derived from a high molecular weight polyisobutylene having a number average molecular weight of 2,000 or greater, having 0.5 to 1 weight percent nitrogen, and post-treated with a phosphorus-containing compound and a boron-containing compound to deliver 70 to 140 ppm phosphorus and 150 to 300 ppm nitrogen to said electric motor lubricating fluid; an amine salt of a phosphoric acid ester providing 40 to 70 ppm phosphorus to said electric motor lubricating fluid; an oil soluble phosphorus anti-wear additive comprising an ashless dialkyldithiophosphate providing 40 to 70 ppm phosphorus to said electric motor lubricating fluid; a sulfur-providing additive comprising a thiadiazole or derivative thereof providing up to 950 ppm sulfur to said electric motor lubricating fluid; An electric motor lubricating fluid having a kV100°C of 4.5 cSt or less and 150-250 ppm total phosphorus.

2. The amine salt of a phosphate ester has the structure of Formula I, or a solvate or hydrate thereof: 【Chemistry 1】 During the ceremony, R 1 and R 2 are independently hydrogen or a linear, branched, or cyclic hydrocarbyl group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R 3 , R 4 , R 5 and R 6 are independently hydrogen or a hydrocarbyl group; R 3 ~R 6 10. The electric motor lubricating fluid of claim 1, wherein at least one of is a hydrocarbyl group.

3. 10. The electric motor lubricating fluid of claim 1, wherein the high molecular weight polyisobutylene has a number average molecular weight of 2,000 to 2,300, and / or the electric motor lubricating fluid comprises 2 to 4 weight percent of the succinimide dispersant.

4. 2. The electric motor lubricating fluid of claim 1, wherein the succinimide dispersant, the amine salt of a phosphoric acid ester, the ashless dialkyldithiophosphate, and the thiadiazole or derivative thereof are provided in an additive concentrate, the additive concentrate having a kV100°C of 15 to 80 cSt, and / or the ratio of kV100°C of the additive concentrate to kV100°C of the electric motor lubricating fluid is from 5:1 to 30:

1.

5. 10. The electric motor lubricating fluid of claim 1, wherein the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after the electric motor lubricating fluid is aged according to CEC L-48-A, and / or the electric motor lubricating fluid achieves a failure load stage of at least 8 in the FZG A10 / 16.6R / 90 Scuffing Test of CEC L-84-02, and / or the electric motor lubricating fluid has an electrical conductivity of 60 nS / M or less, measured by a Modified Conductivity Test according to ASTM D2624-15 using the electric motor lubricating fluid, measured at 20 Hz and 100°C.

6. The oil soluble phosphorus anti-wear additive comprising the ashless dialkyl dithiophosphate is made by a process comprising: (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; and further reacting the reaction product with an unsaturated carboxylic acid to form the oil soluble phosphorus anti-wear additive comprising the ashless dialkyl dithiophosphate; and / or the ashless dialkyl dithiophosphate comprises a compound of Formula II or a salt thereof: 【Chemistry 2】 R 7 and R 8 is independently 3 ~C 8 is a linear or branched alkyl group; R 9 is -H or -CH 3 2. The electric motor lubricating fluid of claim 1 , wherein

7. The thiadiazole or derivative thereof includes one or more compounds having the structure of Formula III: 【Chemistry 3】 During the ceremony, Each R 10 are independently hydrogen or sulfur; Each R 11 are independently an alkyl group; n is an integer of 0 or 1; R 10 is hydrogen, the adjacent R 11 The integer n in the moiety is 0, and R 10 is sulfur, the adjacent R 11 the integer n of the moiety is 1, At least one R 10 10. The electric motor lubricating fluid of claim 1, wherein: is sulfur.

8. 10. The electric motor lubricating fluid of claim 1, further comprising one or more metal-containing detergent additives providing said electric motor lubricating fluid with 50 ppm or less of calcium.

9. 1. An additive concentrate for an electric motor lubricating fluid comprising: a succinimide dispersant derived from a high molecular weight polyisobutylene having a number average molecular weight of 2,000 or greater, having 0.5 to 1 weight percent nitrogen, post-treated with a phosphorus-containing compound and a boron-containing compound, and present in an amount to deliver 1400 to 2450 ppm phosphorus and 3000 to 5400 ppm nitrogen to said additive concentrate; an amine salt of a phosphoric acid ester providing 1000 to 1500 ppm phosphorus to the additive concentrate; an oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate providing from 800 ppm to 1300 ppm of phosphorus to said additive concentrate; a sulfur-providing additive comprising a thiadiazole or derivative thereof providing sulfur to the additive concentrate, the sulfur-providing additive providing 18,000 ppm or less of sulfur; An additive concentrate having a kV100°C of 15 cSt to 80 cSt.

10. 10. The additive concentrate of claim 9, wherein said number average molecular weight of said high molecular weight polyisobutylene is from 2,000 to 2,300, and / or said succinimide dispersant comprises from 40 to 70 weight percent of said additive concentrate, and / or further comprises one or more metal-containing detergent additives providing said additive concentrate with up to 950 ppm calcium.

11. 1. A method for lubricating a driveline component including an electric motor, comprising: lubricating the driveline components with an electric motor lubricating fluid, the electric motor lubricating fluid contacting parts of the electric motor; (ii) a succinimide dispersant derived from a high molecular weight polyisobutylene having a number average molecular weight of 2,000 or greater, having 0.5 to 1 weight percent nitrogen, and post-treated with a phosphorus-containing compound and a boron-containing compound to deliver 70 to 140 ppm phosphorus and 150 to 300 ppm nitrogen to the electric motor lubricating fluid; (iii) an amine salt of a phosphoric acid ester providing 40 to 70 ppm phosphorus to the electric motor lubricating fluid; (iv) an oil soluble phosphorus antiwear additive comprising an ashless dialkyldithiophosphate providing 40 to 70 ppm phosphorus to the electric motor lubricating fluid; and (v) a sulfur providing additive comprising a thiadiazole or derivative thereof providing sulfur to the electric motor lubricating fluid but not exceeding 950 ppm sulfur. wherein the electric motor lubricating fluid has a kV100°C of 3.5 cSt or less, 150-200 ppm total phosphorus, and an electrical conductivity of 37 nS / M or less, measured by a modified conductivity test in accordance with ASTM D2624-15 using the electric motor lubricating fluid, measured at 20 Hz and 100°C.

12. 12. The method of claim 11, wherein the number average molecular weight of the high molecular weight polyisobutylene is from 2,000 to 2,300, and / or the electric motor lubrication fluid comprises 2 to 4 weight percent of the succinimide dispersant.

13. 12. The method of claim 11, wherein the succinimide dispersant, the amine salt of a phosphoric acid ester, the oil soluble phosphorus anti-wear additive comprising an ashless dialkyldithiophosphate, and the sulfur providing additive comprising a thiadiazole or derivative thereof are provided in an additive concentrate having a kV100°C of 15 to 80 cSt, and / or the electric motor lubricating fluid further comprises one or more metal-containing detergent additives providing 50 ppm or less of calcium to the electric motor lubricating fluid.

14. 14. The method of claim 13, wherein the ratio of kV 100°C of the additive concentrate to kV 100°C of the electric motor lubricating fluid is from 5:1 to 30:

1.

15. 12. The method of claim 11, wherein the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after the electric motor lubricating fluid is aged according to CEC L-48-A, and / or the electric motor lubricating fluid achieves a failure load stage of at least 8 in the FZG A10 / 16.6R / 90 scuffing test of CEC L-84-02.

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