Low viscosity lubricating fluids for electric motor systems

Abstract

An electric motor lubricating fluid for use in an electric motor system, the electric motor lubricating fluid comprising a lubricating base oil, at least one vulcanizing component, at least two phosphorus-donating additives, and at least one high molecular weight dispersant. The electric motor lubricating fluid provides acceptable wear performance as well as good electrical conductivity and oxidative stability for use in electric motor system fluids having low viscosity.

Description

Technical Field

[0001] The present disclosure relates to a lubricating fluid for an electric motor system and a method for lubricating gears and clutches in an electric motor system. In particular, the disclosed method and lubricating fluid relate to a low-viscosity lubricating fluid for use in an electric motor of an electric or hybrid electric vehicle, the low-viscosity lubricating fluid comprising an oil of lubricating viscosity and at least one relatively high molecular weight dispersant. Background Art

[0002] The main challenges in developing lubricants for electric vehicle powertrains are achieving acceptable wear and friction properties and maintaining oxidation stability, while ensuring compatibility with the live components in the powertrain. Because lubricants in electric or hybrid electric vehicles may also come into contact with components in the electric motor, the fluid's electrical conductivity also needs to be relatively low to inhibit static charge accumulation and discharge from the live components.

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

[0004] In one embodiment, an electric motor lubricating fluid suitable for use in electric or hybrid electric vehicles is described herein. In various methods, the electric motor lubricating fluid comprises: one or more base oils of lubricating viscosity; a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 2,000 or greater, wherein the succinimide dispersant has from about 0.5 wt % to about 1 wt % nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers from about 70 ppm to about 140 ppm phosphorus and from about 150 ppm to about 300 ppm nitrogen to the electric motor lubricating fluid; an amine salt of a phosphate ester, wherein the succinimide dispersant is a ... and The amine salt of the phosphate ester provides about 40 ppm to about 70 ppm of phosphorus to the electric motor lubricating fluid; an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, the oil-soluble phosphorus antiwear additive providing about 40 ppm to about 70 ppm of phosphorus to the electric motor lubricating fluid; a sulfur-donating additive comprising a thiadiazole or a derivative thereof, the sulfur-donating additive providing up to about 950 ppm of sulfur to the electric motor lubricating fluid; and wherein the electric motor lubricating fluid has a kV100°C of about 4.5 cSt or less and about 150 ppm to about 250 ppm of total phosphorus.

[0005] In other methods or embodiments, the electric motor lubrication of the previous paragraph can include one or more optional features or embodiments in any combination. These optional features or embodiments can include one or more of the following: wherein the amine salt of the phosphate ester has the structure of Formula I or a solvate or hydrate thereof:

[0006]

[0007] wherein R1 and R2 are independently hydrogen or a linear, branched or cyclic hydrocarbon 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 hydrocarbon group, and at least one of R3 to R6 is a hydrocarbon group; and / or wherein R1 and R2 are independently C3 to C 10 an alkyl group, and wherein at least one of R3, R4, R5 and R6 is C 10 to C 20alkyl groups; and / or the high molecular weight polyisobutylene has a number average molecular weight of from about 2,000 to about 2,300; and / or wherein the electric motor lubricating fluid comprises from about 2 wt % to about 4 wt % of a succinimide dispersant; and / or wherein the succinimide dispersant, the amine salt of the phosphate ester, the ashless dialkyl dithiophosphate, and the thiadiazole or derivative thereof are provided in an additive concentrate, and wherein the additive concentrate has a kV100°C of from about 15 cSt to about 80 cSt; and / or wherein 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 wherein the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after aging according to CEC L-48-A); and / or wherein the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after aging according to CEC L-48-A); and / or wherein the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after aging according to CEC L-84-02 FZG A10 / 16.6R / 90 Scuff Resistance Test achieves a failure load rating of at least 8; and / or wherein the electric motor lubricating fluid has an electrical conductivity of about 60 nS / M or less, as measured using an electric motor lubricating fluid according to a modified electrical conductivity test of ASTM D2624-15 and measured at 20 Hz and 100° C.; and / or an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate is prepared 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 an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate; and / or wherein the ashless dialkyl dithiophosphate comprises a compound of formula II or a salt thereof:

[0008]

[0009] wherein R7 and R8 are independently C3 to C8 linear or branched alkyl groups, and R9 is -H or -CH3; and / or wherein the ashless dialkyl dithiophosphate is 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methylpropionic acid; and / or wherein the thiadiazole or derivative thereof comprises one or more compounds having the structure of Formula III:

[0010]

[0011] Each R 10 are independently hydrogen or sulfur; each R 11 are independently alkyl groups; n is an integer of 0 or 1, and if R 10 is hydrogen, then the adjacent R 11 The integer n of the part is 0, and if R 10 is sulfur, then the adjacent R 11 wherein n is 1; and wherein at least one R 10is sulfur; and / or the electric motor lubricating fluid further comprises one or more metal-containing detergent additives that provide no more than about 50 ppm of calcium to the electric motor lubricating fluid.

[0012] In other embodiments, the present disclosure provides an additive concentrate suitable for use in an electric motor lubricating fluid. In various methods, 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, wherein the succinimide dispersant has from about 0.5 wt % to about 1 wt % nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant is present in an amount to deliver from about 1400 ppm to about 2450 ppm phosphorus and from about 3000 ppm to about 5400 ppm nitrogen to the dispersant additive concentrate; an amine salt of a phosphate ester, The amine salt of the phosphate ester provides about 1000 ppm to about 1500 ppm of phosphorus to the additive concentrate; an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, the oil-soluble phosphorus antiwear additive providing about 800 ppm to about 1300 ppm of phosphorus to the additive concentrate; a sulfur-donating additive comprising a thiadiazole or a derivative thereof, the sulfur-donating additive providing sulfur to the additive concentrate, but not exceeding about 18,000 ppm of sulfur; and wherein the additive concentrate has a kV100°C of about 15 cSt to about 80 cSt.

[0013] In other embodiments, the additive concentrate of the previous paragraph may include one or more optional features or embodiments in any combination. These optional features or embodiments may include one or more of the following: wherein the amine salt of the phosphate ester has the structure of Formula I or a solvate or hydrate thereof:

[0014]

[0015] wherein R1 and R2 are independently hydrogen or a linear, branched or cyclic hydrocarbon 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 hydrocarbon group, and at least one of R3 to R6 is a hydrocarbon group; and / or wherein R1 and R2 are independently C3 to C10 alkyl groups, and wherein at least one of R3, R4, R5 and R6 is C 10 to C 20alkyl groups; and / or the high molecular weight polyisobutylene has a number average molecular weight of from about 2,000 to about 2,300; and / or wherein the succinimide dispersant comprises from about 40 weight percent to about 70 weight percent of the additive concentrate; and / or the oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate is prepared 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 an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate; and / or wherein the ashless dialkyl dithiophosphate comprises a compound of formula II or a salt thereof:

[0016]

[0017] wherein R7 and R8 are independently C3 to C8 linear or branched alkyl groups, and R9 is -H or -CH3; and / or wherein the ashless dialkyl dithiophosphate is 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methylpropionic acid; and / or wherein the thiadiazole or derivative thereof comprises one or more compounds having the structure of Formula III:

[0018]

[0019] Each R 10 are independently hydrogen or sulfur; each R 11 are independently alkyl groups; n is an integer of 0 or 1, and if R 10 is hydrogen, then the adjacent R 11 The integer n of the part is 0, and if R 10 is sulfur, then the adjacent R 11 wherein n is 1; and wherein at least one R 10 is sulfur; and / or the additive concentrate further comprises one or more metal-containing detergent additives that provide no more than about 950 ppm of calcium to the additive concentrate.

[0020] In other embodiments, a method for lubricating a drivetrain component including an electric motor is also described herein. In each method, the method includes lubricating the drivetrain component with an electric motor lubricating composition, and wherein the electric motor lubricating composition contacts a portion of the electric motor; and wherein the electric motor lubricating composition comprises: (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 about 2,000 or greater, wherein the succinimide dispersant has from about 0.5 wt % to about 1 wt % nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers from about 70 ppm to about 140 ppm phosphorus and from about 150 ppm to about 300 ppm nitrogen to the electric motor lubricating fluid; and (iii) an amine salt of a phosphate ester, the amine salt of the phosphate ester (iv) an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, the oil-soluble phosphorus antiwear additive providing about 40 ppm to about 70 ppm of phosphorus to the electric motor lubricating fluid; and (v) a sulfur-donating additive comprising a thiadiazole or a derivative thereof, the sulfur-donating additive providing sulfur to the electric motor lubricating fluid, but not more than about 950 ppm of sulfur; and wherein the electric motor lubricating fluid has a kV100°C of about 4.5 cSt or less, about 150 ppm to about 250 ppm of total phosphorus, and a conductivity of about 37 nS / M or less, as measured using the electric motor lubricating fluid according to a modified conductivity test of ASTM D2624-15 and measured at 20 Hz and 100°C.

[0021] In further embodiments, the method for lubricating a powertrain component including an electric motor of the previous 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: wherein the amine salt of the phosphate ester has the structure of Formula I or a solvate or hydrate thereof:

[0022]

[0023] wherein R1 and R2 are independently hydrogen or a linear, branched or cyclic hydrocarbon 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 hydrocarbon group, and at least one of R3 to R6 is a hydrocarbon group; and / or wherein R1 and R2 are independently C3 to C 10 an alkyl group, and wherein at least one of R3, R4, R5 and R6 is C 10 to C 20alkyl groups; and / or the high molecular weight polyisobutylene has a number average molecular weight of from about 2,000 to about 2,300; and / or wherein the electric motor lubricating fluid comprises from about 2 weight percent to about 4 weight percent of a succinimide dispersant; and / or wherein the succinimide dispersant, the amine salt of the phosphate ester, the oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, and the sulfur-donating additive comprising a thiadiazole or a derivative thereof are provided in an additive concentrate having a kV100°C of from about 15 cSt to about 80 cSt; and / or wherein 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 wherein the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after aging according to CEC L-48-A; and / or wherein the electric motor lubricating fluid has a viscosity change of less than 0.09 cSt after aging according to CEC L-84-02 FZG A breaking load rating of at least 8 is achieved in the A10 / 16.6R / 90 scuff resistance test; and / or the oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate is prepared 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 an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate; and / or wherein the ashless dialkyl dithiophosphate comprises a compound of formula II or a salt thereof:

[0024]

[0025] wherein R7 and R8 are independently C3 to C8 linear or branched alkyl groups, and R9 is -H or -CH3; and / or wherein the ashless dialkyl dithiophosphate is 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methylpropionic acid; and / or wherein the thiadiazole or derivative thereof comprises one or more compounds having the structure of Formula III:

[0026]

[0027] Each R 10 are independently hydrogen or sulfur; each R 11 are independently alkyl groups; n is an integer of 0 or 1, and if R 10 is hydrogen, then the adjacent R 11 The integer n of the part is 0, and if R 10 is sulfur, then the adjacent R 11 wherein n is 1; and wherein at least one R 10 is sulfur; and / or wherein the electric motor lubricating composition further comprises one or more metal-containing detergent additives that provide no more than about 50 ppm of calcium to the electric motor lubricating composition.

[0028] In further embodiments, the present disclosure provides use of an additive concentrate in an electric motor lubricating composition and / or use of an electric motor lubricating composition to achieve a kV100°C of about 4.5 cSt or less for an electric motor lubricating composition with about 150 ppm to about 250 ppm total phosphorus and having an electrical conductivity of about 37 nS / M or less as measured using an electric motor lubricating fluid according to a modified conductivity test of ASTM D2624-15 and measured at 20 Hz and 100°C. In other embodiments, the use includes an electric motor lubricating composition comprising: (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 about 2,000 or greater, wherein the succinimide dispersant has from about 0.5 wt % to about 1 wt % nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers from about 70 ppm to about 140 ppm of the lubricating fluid to the electric motor. ppm phosphorus and about 150 ppm to about 300 ppm nitrogen; (iii) an amine salt of a phosphate ester, the amine salt of the phosphate ester providing about 40 ppm to about 70 ppm phosphorus to the electric motor lubricating fluid; (iv) an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, the oil-soluble phosphorus antiwear additive providing about 40 ppm to about 70 ppm phosphorus to the electric motor lubricating fluid; and (v) a sulfur-donating additive comprising a thiadiazole or a derivative thereof, the sulfur-donating additive providing sulfur to the electric motor lubricating fluid, but not more than about 950 ppm sulfur. In other methods or embodiments, the use may also include any other embodiment of the electric motor lubricating composition, any other embodiment of the method, or any other embodiment of the additive concentrate as described above in the context of the present invention.

[0029] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.

[0030] The following definitions of terms are provided to clarify the meaning of certain terms as used herein.

[0031] The terms "lubricating oil," "lubricant composition," "lubricating composition," "lubricant," and "lubricating and cooling fluid" refer to a finished lubricating product comprising a major amount of base oil and a minor amount of an additive composition.

[0032] As used herein, the terms "additive package," "additive concentrate," and "additive composition" refer to that portion of a lubricating oil composition that does not include a major amount of base oil.

[0033] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from a hydrocarbon substituent and a hydrocarbon substituent substituted with one or more of a halogen group, a hydroxyl group, an alkoxy group, a mercapto group, a nitro group, a nitroso group, an amino group, a pyridyl group, a furyl group, an imidazolyl group, oxygen, and nitrogen, and wherein no more than two non-hydrocarbon substituents are present for every ten carbon atoms in the hydrocarbyl group.

[0034] As used herein, unless expressly stated otherwise, the term "weight percent" or "wt%" means the percentage of the component by weight of the entire composition.

[0035] As used herein, the terms "soluble," "oil-soluble," or "dispersible" may, but do not necessarily, mean that the compound or additive is soluble, dissolvable, miscible, or capable of being suspended in oil in all proportions. However, the aforementioned terms do mean that they are, for example, soluble, suspendable, dissolvable, or stably dispersible in the oil to an extent sufficient to exert their intended effect in the environment in which the oil is employed. Furthermore, the additional incorporation of other additives may also allow for the incorporation of higher levels of a particular additive, if desired.

[0036] As used herein, the term "alkyl" refers to a straight chain, branched chain, cyclic and / or substituted saturated chain moiety of about 1 to about 200 carbon atoms.

[0037] As used herein, the term "alkenyl" refers to a straight chain, branched, cyclic and / or substituted unsaturated chain moiety of about 3 to about 30 carbon atoms.

[0038] As used herein, the term "aryl" refers to monocyclic and polycyclic aromatic compounds that may include alkyl, alkenyl, alkylaryl, amino, hydroxy, alkoxy, halogen substituents and / or heteroatoms including, but not limited to, nitrogen and oxygen.

[0039] As used herein, "number average molecular weight" or "Mn" is determined by gel permeation chromatography (GPC) using commercially available polystyrene standards with an Mn of about 180 to about 18,000 as a calibration reference.

[0040] It should be understood that throughout this disclosure, the terms "comprising," "including," "containing," and the like are considered open ended and include any elements, steps, or ingredients not expressly listed. The phrase "consisting essentially of" is meant to include any expressly listed elements, steps, or ingredients 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 "comprising," "including," or "containing" is also to be interpreted as including disclosure of the same composition as "consisting essentially of" or "consisting of" its specifically listed components. DETAILED DESCRIPTION

[0041] According to exemplary embodiments, described herein are electric motor lubricating fluids suitable for electric or hybrid electric vehicles that have a low viscosity of about 4.5 cSt or less, about 3.5 cSt or less, or about 3.0 cSt or less at kV100°C, while still being able to pass demanding FZG wear resistance tests (such as the A10 / 16.6R / 90 test of CEC L-84-02) while achieving good electrical conductivity and maintaining oxidative stability. However, surprisingly, with respect to the lubricating fluids herein, it was discovered that a combination of certain additives, including a succinimide dispersant derived from a relatively high molecular weight polyisobutylene, facilitated the achievement of passing the wear, conductivity, and oxidation performance tests. When the selected relatively high molecular weight dispersants described herein were incorporated into the additive concentrate, an additive concentrate having a relatively high viscosity was produced. Such high viscosity additive concentrates have not previously been used in low viscosity finished lubricants requiring stringent wear protection, low conductivity, and oxidation stability, such as 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.

[0042] It would not be expected that a relatively high viscosity additive concentrate having a relatively high molecular weight succinimide dispersant would be suitable for forming a low viscosity finished lubricant capable of passing wear, conductivity, and oxidation performance tests for electric and / or hybrid electric vehicles. However, when the relatively high molecular weight succinimide dispersants selected herein are mixed with other lubricant additives having certain elemental relationships to form a finished lubricant, the finished lubricants herein achieve low viscosity, passing wear performance, suitable conductivity, and oxidation stability for powertrains having electric or hybrid electric motors.

[0043] It has been discovered herein that relatively high molecular weight polyisobutylene dispersants can be provided in fluids for such electric or hybrid electric applications with low finished fluid viscosity if such high molecular weight dispersants are also provided in the finished fluid in combination with selected amounts of phosphorus, nitrogen, and / or sulfur from other additives, including, for example, amine salts of phosphate esters, ashless dialkyl dithiophosphates, and thiadiazoles or derivatives thereof. In one approach, for example, the fluids herein include: (i) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 2,000 or greater and having up to 1 weight percent nitrogen, post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers from about 60 ppm to about 120 ppm phosphorus and from about 150 ppm to about 300 ppm nitrogen to the electric motor lubricating fluid; and (ii) an amine salt of a phosphate ester that provides from about 45 ppm to about 75 ppm nitrogen to the electric motor lubricating fluid. (iii) an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, the oil-soluble phosphorus antiwear additive providing from about 40 ppm to about 70 ppm of phosphorus to the electric motor lubricating fluid; (iv) a sulfur-donating additive comprising a thiadiazole or a derivative thereof, the sulfur-donating additive providing no more than sulfur to the lubricant, but providing no more than about 950 ppm of sulfur to the electric motor lubricating fluid; and wherein the electric motor lubricating fluid has a kV100°C (ASTM D4450) of about 4.5 cSt or less, about 3.5 cSt or less, or about 3.0 cSt or less, from about 150 ppm to about 250 ppm total phosphorus, and a conductivity of about 60 nS / M or less as measured by using the electric motor lubricating fluid according to a modified conductivity test of ASTM D2624-15 and measured at about 20 Hz and about 100°C. In other embodiments, the lubricants herein may also contain an amount of calcium from a detergent additive (such as up to about 50 ppm calcium in the lubricant or up to about 950 ppm calcium from an additive concentrate for a neutral to low alkaline detergent). Each of the component additives is further described below.

[0044] Succinimide dispersant :

[0045] The electric motor lubricating fluid herein contains a dispersant system comprising 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 2,000 or greater, and which has also been post-treated with a phosphorus-containing compound and a boron-containing compound. At a suitable treatment rate, such a relatively high molecular weight succinimide dispersant produces a dispersant additive concentrate having a kV100°C (ASTM D445) of about 15 cSt to about 80 cSt. The succinimide dispersant 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 in US Pat. No. 7,897,696 and / or US Pat. No. 4,234,435, which are incorporated herein by reference.

[0046] The relatively high molecular weight hydrocarbyl portion of the hydrocarbyl dicarboxylic acid or anhydride can be derived from a butene polymer, such as a polymer of isobutylene. Suitable polyisobutylenes for use herein include those formed from conventional polyisobutylene or highly reactive polyisobutylenes having a terminal vinylidene content of at least 60%, such as 70% to 90% and higher. Suitable polyisobutylenes may include those prepared using a BF3 catalyst.

[0047] The dispersants herein have a relatively high molecular weight, and thus, the number average molecular weight of the polyisobutylene substituents of the dispersants herein can vary from at least about 2,000, and in some cases, up to about 3,000, as measured by gel permeation chromatography (GPC) using polystyrene (which has a number average molecular weight of 180 to about 18,000) as a calibration reference. The GPC method also provides weight average molecular weight distribution information; see, for example, W. W. Yau, J. J. Kirkland, and D. D. Bly, "Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New York, 1979, which is also incorporated herein by reference.

[0048] The polyisobutylene portion of the dispersants herein may also have a molecular weight distribution (MWD) as determined by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), also known as the polydispersity index. In some methods or embodiments, suitable polyisobutylene portions may have a Mw / Mn of less than about 3.0, or less than about 2.8, or less than about 2.5, and in other methods, suitable polyisobutylene substituents have a polydispersity of from about 1.5 to about 3.0, or from about 2.0 to about 3.0.

[0049] The dicarboxylic acid or anhydride suitable for forming a dispersant herein can be selected from carboxylic acid reactants, such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethylmaleic anhydride, dimethylmaleic anhydride, ethylmaleic acid, dimethylmaleic acid, hexylmaleic acid etc., including corresponding acid halides and C1-C4 aliphatic esters. In some methods, the mol ratio of the dicarboxylic acid or anhydride to the alkyl moiety in the reaction mixture for preparing alkyl-dicarboxylic acid or anhydride can be widely changed. Therefore, the feed molar ratio can change from 5: 1 to 1: 5, for example, from 3: 1 to 1: 3. In some embodiments, the particularly suitable mol ratio of acid or anhydride to alkyl moiety is 1: 1 to less than 1.6: 1. In other embodiments, another useful feed molar ratio of dicarboxylic acid or anhydride to hydrocarbyl moiety can be 1:1 to 1.5:1, or 1:1 to 1.4:1, or 1.1:1 to 1.3:1, or 1:1 to 1.2:1.

[0050] Any of many polyalkylene polyamines can be used as the dispersant additive for preparing this article. Non-limiting exemplary polyamines can include aminoguanidine bicarbonate (AGBC), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA) and heavy polyamines. Heavy polyamines can include a mixture of polyalkylene polyamines with a small amount of polyamine oligomers, such as TEPA and PEHA, but mainly oligomers with seven or more nitrogen atoms, two or more primary amines per molecule, and more extensive branching than conventional polyamine mixtures. Typically, these heavy polyamines have an average of 6.5 nitrogen atoms per molecule. Other non-limiting polyamines that can be used to prepare hydrocarbyl-substituted succinimide dispersants are disclosed in US 6,548,458, the disclosure of which is incorporated herein by reference as a whole. In some embodiments, the feed mole ratio of hydrocarbyl-dicarboxylic acid or anhydride to polyalkylene polyamines can be from about 1:1 to about 3.0:1. In one embodiment, the dispersant of the present disclosure described herein can be the reaction product of polyisobutenyl succinic anhydride (PIBSA) and a polyamine (e.g., a heavy polyamine), wherein the feed molar ratio of polyisobutenyl substituted succinic anhydride to polyamine is from about 1.7:1 to about 2.5:1.

[0051] As described above, the high molecular weight succinimide dispersants herein can be post-treated with boron compounds. Suitable boron compounds that can be used to form the dispersants herein include any boron compound or mixture of boron compounds that can introduce a boron-containing substance into an ashless dispersant. Any organic or inorganic boron compound capable of such a reaction can be used. Thus, boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF4, boronic acids such as borous acid (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 these boronic acids, and esters of these boronic acids can be used. The use of complexes of boron trihalides with ethers, organic acids, inorganic acids, or hydrocarbons is a convenient method for introducing the boron reactant into the reaction mixture. Such complexes are known, for example boron trifluoride-diethyl ether, boron trifluoride-phenol, boron trifluoride-phosphoric acid, boron trichloride-chloroacetic acid, boron tribromide-dioxane and boron trifluoride-methyl ethyl ether.

[0052] The high molecular weight succinimide dispersants herein may also be post-treated with a phosphorus compound. Suitable phosphorus compounds for forming the dispersants herein include phosphorus compounds or mixtures of phosphorus compounds that are capable of introducing phosphorus-containing species into the ashless dispersant. Thus, any organic or inorganic phosphorus compound capable of undergoing this reaction may be used. Thus, inorganic phosphorus compounds such as inorganic phosphoric acid and inorganic phosphorus oxides, including their hydrates, may be used. Typical organophosphorus compounds include full and partial esters of phosphoric acid, such as mono-, diesters, and triesters of phosphoric acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid, and tetrathiophosphoric acid; mono-, diesters, and triesters of phosphite, thiophosphorous acid, dithiophosphorous acid, and trithiophosphorous acid; trihydrocarbylphosphine oxides; trihydrocarbylphosphine sulfides; mono- and dihydrocarbylphosphonates (RPO(OR')(OR"), wherein R and R' are hydrocarbyl groups and R" is a hydrogen atom or a hydrocarbyl group), and their monothio, dithio, and trithio analogs; mono- and dihydrocarbylphosphinates (RP(OR')(OR"), wherein R and R' are hydrocarbyl groups and R" is a hydrogen atom or a hydrocarbyl group), and their monothio and dithio analogs; and the like. Thus, compounds such as phosphorous acid (H3PO3, sometimes described as H2(HPO3), sometimes called o-phosphorous acid or phosphonic acid), phosphoric acid (H3PO4, sometimes called orthophosphoric acid), hypophosphorous acid (H4P2O6), metaphosphoric acid (HPO3), pyrophosphoric acid (H4P2O7), hypophosphorous acid (H3PO2, sometimes called phosphinic acid), pyrophosphorous acid (H4P2O5, sometimes called pyrophosphonic acid), phosphinic acid (H3PO), tripolyphosphoric acid (H5P3O 10 ), tetrapolyphosphate (H5P4O 13), trimetaphosphoric acid (H3P3O9), phosphorus trioxide, phosphorus tetroxide, phosphorus pentoxide, etc. Partial sulfur or full sulfur analogs such as tetrathioacetic acid (H3PS4), thiophosphoric acid (H3PO3S), dithiophosphoric acid (H3PO2S2), trithiophosphoric acid (H3POS3), phosphorus sesquisulfide, phosphorus heptasulfide and phosphorus pentasulfide (P2S5, sometimes called P4S 10 ), can also be used to form the dispersant of the present disclosure. Inorganic phosphorus halides such as PCl 3 , PBr 3 , POCl 3 , PSCl 3 and the like can also be used.

[0053] Likewise, organophosphorus compounds may be used, such as monoesters, diesters, and triesters of phosphoric acid (e.g., trihydrocarbyl phosphates, dihydrocarbyl monophosphates, monohydrocarbyl diacid phosphates, and mixtures thereof), monoesters, diesters, and triesters of phosphorous acid (e.g., trihydrocarbyl phosphites, dihydrocarbyl hydrogen phosphites, hydrocarbyl diacid phosphites, and mixtures thereof), phosphonates ("primary" RP(O)(OR)2 and "secondary" R2P(O)(OR)), phosphinates, phosphonyl halides (e.g., RP(O)Cl2 and R2P(O)Cl2), ), halophosphites (e.g., (RO)PCl2 and (RO)2PCl), halophosphates (e.g., ROP(O)Cl2 and (RO)2P(O)Cl), tertiary pyrophosphates (e.g., (RO)2P(O)-OP(O)(OR)2), and fully or partially sulfur analogs of any of the foregoing organophosphorus compounds, wherein each hydrocarbyl group contains 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. Halophosphine halides (e.g., hydrocarbyl phosphorus tetrahalides, dihydrocarbyl phosphorus trihalides, and trihydrocarbyl phosphorus dihalides) and halophosphines (monohalogenated and dihalogenated phosphines) may also be used.

[0054] In one embodiment, the relatively high molecular weight succinimide dispersant of the fluids herein comprises at least one polyisobutylenyl moiety having a number average molecular weight of at least about 2000, and in other approaches from about 2000 to about 3000, or in other approaches from about 2000 to about 2300, and having from about 0.5 wt % to about 1 wt % nitrogen, from about 0.05 wt % to about 0.25 wt % boron, and from about 0.20 wt % to about 0.45 wt % phosphorus, or in other embodiments, comprises at least one polyisobutylenyl moiety having a number average molecular weight of at least about 2000 to 2300, and having from about 0.60 wt % to about 0.90 wt % nitrogen, from about 0.10 wt % to about 0.20 wt % boron, and from about 0.25 wt % to about 0.40 wt % phosphorus.

[0055] In some embodiments, the relatively high molecular weight dispersants described herein may comprise from about 40% to about 70% by weight of the additive concentrate. In some embodiments, the relatively high molecular weight succinimide dispersants described herein include at least one polyisobutylene moiety having a number average molecular weight of from about 2000 to about 2300 and have from about 0.6% to about 0.9% by weight nitrogen, from about 0.10% to about 0.20% by weight boron, and from about 0.25% to about 0.40% by weight phosphorus, and may comprise from about 40% to about 70% by weight of the additive concentrate. In some embodiments, the relatively high molecular weight succinimide dispersants described herein include at least one polyisobutylene moiety having a number average molecular weight of from about 2000 to about 2300 and deliver from about 3000 ppm to about 5400 ppm nitrogen, from about 600 ppm to about 1000 ppm boron, and from about 1400 ppm to about 2450 ppm phosphorus to the additive concentrate.

[0056] 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 ppm to about 300 ppm of nitrogen, from about 70 ppm to about 140 ppm of phosphorus, and from about 30 ppm to about 60 ppm of boron. As shown in the examples below, when such succinimide dispersants are mixed with other fluid components, particularly selected amounts of sulfur, boron, nitrogen, and / or phosphorus, the lubricant achieves tested wear and conductivity properties, as well as oxidation stability.

[0057] Amine salts of phosphate esters :

[0058] The electric motor lubricating fluids herein also include a first phosphorus-supplying additive in an amount that provides from about 40 ppm to about 70 ppm of phosphorus from an amine salt to the fluid. In various methods or embodiments, the first phosphorus-supplying additive is in the form of an amine salt of a phosphate ester. In some methods, the amine salt of the phosphate ester may include one or more monoalkyl phosphate esters, dialkyl phosphate esters, and / or mixtures thereof, wherein the alkyl groups thereof may be linear, branched, or cyclic. The fluids herein may also include other compounds that provide phosphorus, but in some embodiments, the amine salt of the phosphate ester herein provides from about 20% to about 40% by weight of the total phosphorus in the electric motor lubricating fluid.

[0059] In various methods or embodiments, exemplary amine salts of phosphate esters may be represented by Formula I

[0060]

[0061] Wherein R3 and R4 of Formula I can independently be hydrogen or a linear, branched or cyclic hydrocarbon 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 independently be hydrogen or a hydrocarbon group, and at least one of R5 to R8 of Formula I is a hydrocarbon group. Examples of suitable alkyl or hydrocarbon 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. In further exemplary methods, R3 and R4 of Formula I can be cyclic hydrocarbon groups and examples include cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclopentyl, dimethylcyclopentyl, methylethylcyclopentyl, diethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl, dimethylcycloheptyl, methylethylcycloheptyl and / or diethylcycloheptyl. In some methods or embodiments, suitable phosphate amine salt is a mixture of monoalkyl and dialkyl phosphate. As mentioned above, monoalkyl and dialkyl can be straight chain, branched or cyclic.

[0062] The amine salt of phosphate ester can be derived from a primary amine, a secondary amine or a tertiary amine, or a mixture thereof. Exemplary amines suitable for use in salts can be aliphatic, cyclic, aromatic or non-aromatic, but are typically aliphatic amines. Examples of suitable primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, bis-(2-ethylhexyl)amine, octylamine and dodecylamine, as well as aliphatic 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, dipentylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine, N-methyl-1-amino-cyclohexane and / or ethylpentylamine. Secondary amines can also be cyclic amines such as piperidine, piperazine and morpholine. Examples of suitable tertiary amines can include tri-n-butylamine, tri-n-octylamine, tridecylamine, trilaurylamine, trihexadecylamine and / or dimethyloleylamine.

[0063] In some methods, the amine of formula I described above may be such that at least one of the R5, R6, R7 or R8 groups is C 10 to C 20 Alkyl groups, and in other methods or embodiments, R5, R6, R7 or R8 groups of Formula I are independently C 10 to C 20 In some embodiments, at least two of the R5, R6, R7 or R8 groups of Formula I are independently C 12 to C 14 Alkyl group.

[0064] Amine salts of phosphate esters can be prepared by reacting a suitable phosphorus compound with an amine to form an amine salt of the phosphate ester. In one embodiment, the amine salt of the phosphate ester can have Formula I, wherein R3 and R4 can independently be C6 or hydrogen; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R5, R6, R7, and R8 can independently be hydrogen or C6. 12 to C 14 and at least one of R5 to R8 is C 12 to C 14 of a hydrocarbon group.

[0065] In embodiments, the amine salt of the phosphate ester may be present in the additive concentrate in an amount from 2 wt % to about 3 wt % or from about 2.2 wt % to about 2.5 wt %. The amine salt of the phosphate ester may deliver from about 1000 ppm to about 1500 ppm of phosphorus or from about 1000 ppm to about 1250 ppm of phosphorus to the additive concentrate.

[0066] In each method, the amine salt of the phosphate ester can be present in the electric motor lubricating fluid herein in an amount of at least about 0.1% to about 0.3% or about 0.1% to about 0.25% by weight of the lubricating composition. The amine salt of the phosphate ester can deliver about 50 ppm to about 150 ppm of phosphorus or about 50 ppm to about 125 ppm of phosphorus to the lubricating composition.

[0067] Ashless dialkyl dithiophosphates :

[0068] In various methods or embodiments, the electric motor lubricating fluids herein may further include a second phosphorus-supplying additive in the form of an acidic thiophosphate or a thiophosphate ester. In one method or embodiment, the second phosphorus-supplying additive may be an ashless, amine-free dialkyl dithiophosphate ester or a sulfur-containing phosphate ester.

[0069] The acidic thiophosphate, phosphorothioate or sulfur-containing phosphate of the second phosphorus compound may have one or more sulfur-phosphorus bonds. In one embodiment, the sulfur-containing phosphate may be an acidic thiophosphate, a thiophosphate, a thiophosphoric acid or a salt thereof. The thiophosphate may be a dithiophosphate. In some more specific methods, the acidic thiophosphate or thiophosphate may have a structure of Formula II or a salt thereof

[0070]

[0071] Wherein R4 and R5 of formula II are each independently a linear or branched C1 to C 10 A hydrocarbon group, and R7 of formula II is C1 to C 10 Straight chain or branched chain carboxyl or C1 to C 10Preferably, R4 and R5 of Formula II are each a C3 to C8 straight or branched chain alkyl ester group and R7 of Formula II is derived from 2-methylpropionic acid, such that the phosphorus product (or its salt) has the structure of Formula II below:

[0072]

[0073] wherein R4 and R5 of the above formula II are independently C3 to C8 linear or branched alkyl groups (preferably branched C4 groups), and R6 of the above formula II is -H or -CH3. In some methods or embodiments, the second phosphorus product is preferably 3-[[bis(2-methylpropoxy)phosphinothioyl]thio]-2-methyl-propionic acid.

[0074] In some methods, an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate is prepared by a process comprising the steps of: (a) reacting an organic hydroxy compound with phosphorus pentasulfide (in some forms, a monomer or dimer thereof) to form a reaction product, and further reacting the reaction product with an unsaturated carboxylic acid to form an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate.

[0075] Suitable organic hydroxy compounds may include normal straight chain alcohols, branched chain alcohols, hydroxyaryl compounds (such as phenol and naphthol), substituted aryl hydroxy compounds (such as diamylphenol), or any other hydroxy organic material in which the hydroxyl group will react with phosphorus pentasulfide. In one approach, the starting alcohol is a saturated alcohol or a substituted aryl hydroxy compound, such as an aryl hydroxy compound substituted with a saturated alkyl radical. In some approaches, the organic hydroxy compound may be a C1 to C2 10 (In other methods, C1 to C6) straight or branched chain alcohols, hydroxyaryl compounds or mixtures thereof, such as one or more of methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol, sec-butanol, phenol, naphthol, amyl alcohol, hexanol, isohexanol, octanol, decanol, dodecanol, octadecanol, 2-ethylhexanol, 4-methyl-2-pentanol, phenyl alcohol, butylphenyl alcohol, cyclohexanol, methylcyclopentanol, propenyl alcohol, butenyl alcohol or combinations thereof. Preferred organic hydroxy compounds herein include C1 to C4 alcohols, such as ethanol, propanol or isopropanol, most preferably, the organic hydroxy compound is isobutanol.

[0076] Suitable unsaturated carboxylic acids for forming the oil-soluble phosphorus antiwear additives of the present disclosure may include a wide variety of unsaturated carboxylic acids or fatty acids. Preferred unsaturated carboxylic acids may include C1 to C 20 Unsaturated fatty acids, such as acrylic acid, methacrylic acid, 2-ethylacrylic acid, or combinations thereof, and most preferably methacrylic acid. (As used herein, (meth)acrylic acid refers to acrylic acid or methacrylic acid).

[0077] In some embodiments, the second phosphorus-supplying additive is an acidic thiophosphate or a thiophosphate ester present in the additive concentrate in an amount that provides 800 ppm to 1300 ppm of phosphorus and less than 2800 ppm of sulfur to the additive concentrate. In another embodiment, the second phosphorus-supplying additive is an acidic thiophosphate or a thiophosphate ester present in the additive concentrate in an amount that provides 900 ppm to 1200 ppm of phosphorus and less than 2500 ppm of sulfur to the additive concentrate. In one approach, the additive concentrate comprises from about 0.80 wt.% to about 1.75 wt.% of the ashless dialkyl dithiophosphate compound, and in other approaches, from about 0.9 wt.% to about 1.40 wt.%, or from about 1.0 wt.% to about 1.3 wt.% of the ashless dialkyl dithiophosphate compound.

[0078] In various methods or embodiments, the electric motor lubricating fluids herein may further comprise a second phosphorus-supplying additive in the form of an ashless dialkyl dithiophosphate compound in an amount to provide the fluid with about 40 ppm to about 70 ppm of phosphorus and less than 160 ppm of sulfur. In some embodiments, the electric motor lubricating fluids herein may comprise a second phosphorus-supplying additive in the form of an ashless dialkyl dithiophosphate compound in an amount to provide about 50 ppm to about 65 ppm of total phosphorus and less than 140 ppm of sulfur. In one method or embodiment, the electric motor lubricating fluids herein comprise about 0.03 wt% to about 0.1 wt% of the ashless dialkyl dithiophosphate compound, and in other methods, about 0.04 wt% to about 0.08 wt%.

[0079] Sulfur-supplying additives :

[0080] The electric motor lubricating fluid comprises a sulfur-supplying additive. In each method or embodiment herein, the sulfur-supplying additive may be one or more thiadiazole compounds or their hydrocarbyl-substituted derivatives in an amount that provides sulfur to the lubricating fluid herein, but not more than about 950 ppm of sulfur. In other methods, the sulfur-supplying compound may be a mixture of thiadiazole compounds or their hydrocarbyl-substituted derivatives. Examples of thiadiazole compounds that can 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 typically synthesized from hydrazine and carbon disulfide by known methods. See, for example, US 2,765,289; US 2,749,311; US 2,760,933; US 2,850,453; US 2,910,439; US 3,663,561; US 3,862,798; and US 3,840,549.

[0081] In each method, the thiadiazole or derivative thereof includes one or more compounds having the structure of Formula III:

[0082]

[0083] wherein each R1 of Formula III is independently hydrogen or sulfur, each R2 of Formula III is independently alkyl, n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, the integer n of the adjacent R2 moiety is 1, with the proviso that at least one R1 is sulfur. In other methods, the thiadiazole additive is a blend of compounds of Formula IIIa and Formula IIIb as shown below:

[0084]

[0085] wherein in Formula IIIa, each integer n is 1, each R1 is sulfur, and each R2 is C5 to C 15 Alkyl groups, preferably C8 to C 12 an alkyl group; and

[0086]

[0087] Wherein in formula IIIb, an integer n is 1, the associated R2 group is C5 to C 15 Alkyl groups (preferably C8 to C 12alkyl group), and the other integer n is 0, and both R1 groups are sulfur. In some embodiments, the sulfur-donating additive comprises a blend of formulas IIIa and IIIb, wherein formula Iva is the majority of the blend, and in other methods, the blend of IIIa and IIIb is about 75% to about 90% by weight of IIIa and about 10% to about 25% by weight of IIIb (or other ranges therein). In another method, the sulfur-donating additive is a 2,5-dimercapto-1,3,4-thiadiazole, which includes 2,5-bis-(nonyldisulfide)-1,3,4-thiadiazole (such as, about 75% to about 90%) and 2,5-mono-(nonyldisulfide)-1,3,4-thiadiazole (such as about 10% to about 25%).

[0088] The thiadiazole compound or its hydrocarbyl substituted derivative is present in the electric motor lubricating fluid herein in an amount to deliver no more than about 950 ppm of sulfur, no more than about 925 ppm of sulfur, or no more than about 900 ppm of sulfur, and in other embodiments at least about 700 ppm of sulfur or at least about 800 ppm of sulfur (or other ranges therein). In one embodiment, the thiadiazole compound is 2,5-dimercapto-1,3,4-thiadiazole, and the thiadiazole compound or its hydrocarbyl substituted derivative is present in the lubricating and cooling fluid in an amount to deliver from about 700 ppm to about 950 ppm of sulfur, or from about 750 ppm to about 900 ppm of sulfur (or other ranges therein).

[0089] base oil :

[0090] The electric motor lubricating fluid herein comprises one or more base oils with lubricating viscosity. The base oil or base oil with lubricating viscosity suitable for formulating the electric motor lubricating fluid for electric and / or hybrid electric motor vehicles according to the present disclosure can be selected from any one of suitable synthetic or natural oils or mixtures thereof with suitable lubricating viscosity. Natural oils can include animal oils and vegetable oils (e.g., castor oil, lard) and mineral oils, such as liquid petroleum oils and solvent-treated or acid-treated paraffin, cycloparaffin or mixed paraffin-cycloparaffin type mineral lubricating oils. Oils derived from coal or shale may also be applicable. In addition, oils derived from gas-to-liquid processes are also applicable. As measured by ASTM D2270-10, the base oil can have a kinematic viscosity of about 2 cSt to about 15 cSt at 100 ° C.

[0091] The base oil used in the present invention as herein described can be a single base oil or can be a mixture of two or more base oils. One or more base oils can be selected from any base oil in Group III or IV specified in the American Petroleum Institute (API) Base Oil Interchangeability Guide. These base oils are shown in Table 1 below:

[0092] Table 1

[0093]

[0094] In one variant, the base oil can be selected from API Group III base oils, or API Group IV base oils, or mixtures of these base oils. Alternatively, the base oil can be a mixture of two or more of the API Group III base oils or two or more of the API Group IV base oils.

[0095] API Group III base oils may include oils derived from Fischer-Tropsch synthesized hydrocarbons. Fischer-Tropsch synthesized hydrocarbons are produced from synthesis gas containing H2 and CO using a Fischer-Tropsch catalyst. Such hydrocarbons typically require further processing to be used as base oils. These types of oils are commonly referred to as gas-to-liquids (GTLs). For example, hydrocarbons may be hydroisomerized using the methods disclosed in U.S. Patents 6,103,099 or 6,180,575; hydrocracking and hydroisomerization using the methods disclosed in U.S. Patents 4,943,672 or 6,096,940; dewaxing using the methods disclosed in U.S. Patent 5,882,505; or hydroisomerization and dewaxing using the methods disclosed in U.S. Patents 6,013,171, 6,080,301; or 6,165,949.

[0096] API Group IV base oils, PAOs, are typically derived from monomers having 4 to 30, 4 to 20, or 6 to 16 carbon atoms. Examples of PAOs useful in the present invention include those derived from octene, decene, mixtures thereof, and the like. As measured by ASTM D2270-10, the PAO may have a kinematic viscosity at 100°C of 2 to 15, 3 to 12, or 4 to 8 cSt. Examples of PAOs include 4 cSt at 100°C, 6 cSt at 100°C, and mixtures thereof.

[0097] The base oil is combined with the additive composition as disclosed in the embodiments herein to provide a lubricating and cooling fluid for use in an electric motor system having an electric motor, a gear, and a clutch. Thus, the base oil 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.

[0098] Other additives

[0099] In addition to the components described above, the electric motor lubricating fluids described herein may also contain other additives of the type used in transmission fluid compositions. Such additives include, but are not limited to, antioxidants, viscosity modifiers, phosphorus-containing components, detergents, corrosion inhibitors, rust inhibitors, defoamers, demulsifiers, pour point depressants, seal swell agents and additional dispersants, additional friction modifiers, and additional sulfur-containing components.

[0100] 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.

[0101] Examples of phenolic antioxidants include 2,6-di-tert-butylphenol, liquid mixtures of tert-butylphenols, 2,6-di-tert-butyl-4-methylphenol, 4,4'-methylenebis(2,6-di-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), mixed methylene-bridged polyalkylphenols, and 4,4'-thiobis(2-methyl-6-tert-butylphenol), N,N'-di-sec-butyl-phenylenediamine, 4-isopropylaminodiphenylamine, phenyl-α-naphthylamine, phenyl-α-naphthylamine, and cycloalkylated diphenylamines. Examples include hindered tert-butylated phenols, bisphenols, and cinnamic acid derivatives, as well as combinations thereof.

[0102] Aromatic amine antioxidants include, but are not limited to, diarylamines having the formula:

[0103]

[0104] wherein R′ and R″ each independently represents 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 hydroxyl group, a halogen group, a carboxylic acid or ester group, or a nitro group.

[0105] The aryl groups are preferably substituted or unsubstituted phenyl or naphthyl, in particular wherein one or both of these aryl groups are substituted by at least one alkyl group having 4 to 30 carbon atoms, preferably 4 to 18 carbon atoms, most preferably 4 to 9 carbon atoms. Preferably, one or both aryl groups are substituted, for example monoalkylated diphenylamine, dialkylated diphenylamine or a mixture of monoalkylated and dialkylated diphenylamine.

[0106] Examples of diarylamines that can be used include, but are not limited to, diphenylamine; various alkylated diphenylamines, 3-hydroxydiphenylamine, N-phenyl-1,2-phenylenediamine, N-phenyl-1,4-phenylenediamine, monobutyldiphenylamine, dibutyldiphenylamine, monooctyldiphenylamine, dioctyldiphenylamine, monononyldiphenylamine, dinonyldiphenylamine, monotetradecyldiphenylamine, tetracosyldiphenylamine, phenyl-α-naphthylamine, monooctylbenzene-α-naphthylamine, phenyl-β-naphthylamine, monoheptyldiphenylamine, diheptyldiphenylamine, para-oriented styrenated diphenylamines, mixed butyloctyldiphenylamines, and mixed octylstyryldiphenylamines.

[0107] Sulfur-containing antioxidants include, but are not limited to, sulfurized olefins, which are characterized by the type of olefin used in their production and the final sulfur content of the antioxidant. High molecular weight olefins (i.e., those having an average molecular weight of 168 to 351 g / mol) are preferred. Examples of usable olefins include alpha-olefins, isomerized alpha-olefins, branched olefins, cyclic olefins, and combinations of these.

[0108] α-olefins include but are not limited to any C4 to C 25 Alpha-olefins. Alpha-olefins can be isomerized before or during the sulfurization reaction. Structural and / or conformational isomers of alpha-olefins containing internal double bonds and / or branching can also be used. For example, isobutylene is the branched olefin counterpart of the alpha-olefin 1-butene.

[0109] Sulfur sources that can be used in the olefin sulfurization reaction include elemental sulfur, sulfur monochloride, sulfur dichloride, sodium sulfide, sodium polysulfide, and mixtures thereof, which are added together or at different stages of the sulfurization process.

[0110] Unsaturated oils, due to their unsaturation, can also be sulfurized and used as antioxidants. Examples of oils or fats that can be used include corn oil, canola oil, cottonseed oil, grapeseed oil, olive oil, palm oil, peanut oil, coconut oil, rapeseed oil, safflower oil, sesame oil, soybean oil, sunflower oil, tallow, and combinations of these.

[0111] The total amount of antioxidant in the lubricating and cooling fluids described 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 ppm to about 150 ppm nitrogen.

[0112] Friction Modifiers: In some embodiments, the electric motor lubricating fluid includes additional friction modifiers in addition to those included in the friction modifier system described above. Suitable additional friction modifiers may include metal-containing and metal-free friction modifiers and may include, but are not limited to, imidazolines, amides, amines, succinimides, alkoxylated amines, alkoxylated etheramines, amine oxides, amidoamines, nitriles, betaines, quaternary amines, imines, amine salts, aminoguanidines, enolamides, phosphonates, metal-containing compounds, glycerides, sulfurized fatty compounds and olefins, sunflower oil, other naturally occurring plant or animal oils, dicarboxylic acid esters, esters or partial esters of polyols with one or more aliphatic or aromatic carboxylic acids, and the like.

[0113] Suitable friction modifiers may contain a hydrocarbyl group selected from a linear, branched or aromatic hydrocarbyl group or a mixture thereof, and such hydrocarbyl group may be saturated or unsaturated. The hydrocarbyl group may be composed of carbon and hydrogen or heteroatoms (such as sulfur or oxygen). The hydrocarbyl group may be between 12 and 25 carbon atoms. In some embodiments, the friction modifier may be a long-chain fatty acid ester. In another embodiment, the long-chain fatty acid ester may be a monoester or a diester 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.

[0114] Other suitable friction modifiers may include organic, ashless (metal-free), nitrogen-free organic friction modifiers. Such friction modifiers may include esters formed by reacting carboxylic acids and anhydrides with alkanols and generally contain a polar terminal group (e.g., a carboxyl or hydroxyl group) covalently bonded to a lipophilic hydrocarbon chain. An example of an organic ashless, nitrogen-free friction modifier is commonly known as glyceryl monooleate (GMO), which may contain monoesters, diesters, and triesters of oleic acid. Other suitable friction modifiers are described in U.S. Patent No. 6,723,685.

[0115] Amine friction modifiers can include amines or polyamines. Such compounds can have linear saturated or unsaturated hydrocarbon groups or mixtures thereof and can contain 12 to 25 carbon atoms. Other examples of suitable friction modifiers include alkoxylated amines and alkoxylated etheramines. Such compounds can have linear chains, saturated or unsaturated hydrocarbon groups, or mixtures thereof. They can contain from about 12 to about 25 carbon atoms. Examples include ethoxylated amines and ethoxylated etheramines.

[0116] The amines and amides can be used as such or as adducts or reaction products with boron compounds such as boron oxide, boron halides, metaborates, boric acid or mono-, di- or tri-alkyl borate esters.Other suitable friction modifiers are described in US Patent 6,300,291.

[0117] If the additional friction modifier contains nitrogen, such additional friction modifier may be present in the lubricating and cooling fluids in any amount so long as the performance requirements are not compromised.

[0118] Detergents: Metal detergents that may be included in the electric motor lubricating fluids described herein typically comprise a polar head with a long hydrophobic tail, wherein the polar head comprises a metal salt of an acidic organic compound. The salts may contain a substantially stoichiometric amount of the metal, in which case they are typically 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 a metal base may be included by reacting an excess of a metal compound (such as an oxide or hydroxide) with an acidic gas (such as carbon dioxide). The resulting overbased detergent comprises micelles of a neutralizing detergent surrounding a core of an inorganic metal base (e.g., a hydrated carbonate). Such overbased detergents may have a TBN of 150 or higher, such as 150 to 450 or higher.

[0119] Cleaning agents suitable for use in embodiments of the present invention include oil-soluble overbased, underbased, and neutral sulfonates, phenates, sulfurized phenates, and salicylates of metals, particularly alkali or alkaline earth metals (e.g., sodium, potassium, lithium, calcium, and magnesium). More than one metal may be present, such as calcium and magnesium. Mixtures of calcium and / or magnesium with sodium may also be suitable. Suitable metal cleaners may be overbased calcium or magnesium sulfonates having a TBN of 150 to 450 TBN, overbased calcium or magnesium phenates or sulfurized phenates having a TBN of 150 to 300 TBN, and overbased calcium or magnesium salicylates having a TBN of 130 to 350. Mixtures of these salts may also be used.

[0120] The metal-containing detergent can be present in the lubricating and cooling fluid in an amount sufficient to improve the rust prevention properties of the fluid. The metal-containing detergent can be present in the fluid in an amount sufficient to provide up to 90 ppm of alkali metal and / or alkaline earth metal, based on the total weight of the lubricating and cooling fluid. In one example, the metal-containing detergent can be present in an amount sufficient to provide from about 20 ppm to about 50 ppm of alkali metal and / or alkaline earth metal. In another embodiment, the metal-containing detergent can be present in an amount sufficient to provide from about 30 ppm to about 40 ppm of alkali metal and / or alkaline earth metal.

[0121] In one approach, the preferred detergent may be a neutral to low-base sulfonate, and in some approaches is a calcium sulfonate. A suitable detergent may be a calcium sulfonate having a TBN of 50 or less (such as about 25 to about 30) and providing no more than about 50 ppm of calcium to the lubricant. In other approaches, the detergent may provide about 25 ppm to about 40 ppm of calcium, about 30 ppm to about 40 ppm of calcium, or about 30 ppm to about 38 ppm of calcium to the finished electric motor lubricating fluid or composition. With respect to additive concentrates, the detergent may provide more than about 950 ppm of calcium to the additive concentrate, or provide about 500 ppm to about 950 ppm of calcium to the additive concentrate, about 550 ppm to about 900 ppm of calcium, about 600 ppm to about 800 ppm of calcium, or about 600 ppm to about 700 ppm of calcium to the additive concentrate.

[0122] Corrosion Inhibitors: Rust inhibitors or corrosion inhibitors may also be included in the electric motor lubricating fluids described herein. Such materials include monocarboxylic acids and polycarboxylic acids. Examples of suitable monocarboxylic acids are octanoic acid, decanoic acid, and dodecanoic acid. Suitable polycarboxylic acids include dimer and trimer acids, such as those derived from acids such as tall oil fatty acid, oleic acid, linoleic acid, or their analogs.

[0123] Another useful type of rust inhibitor can be alkenyl succinic acid and alkenyl succinic anhydride inhibitors, such as for example tetrapropylene succinic acid, tetrapropylene succinic anhydride, tetradecene succinic acid, tetradecene succinic anhydride, hexadecenyl succinic acid, hexadecenyl succinic anhydride etc. In addition, useful are half esters of alkenyl succinic acid and alcohol (such as polyethylene glycol) having 8 to 24 carbon atoms in the alkenyl group. Other suitable rust inhibitors or inhibitors include etheramines, acid phosphates, amines, polyethoxylated compounds such as ethoxylated amines, ethoxylated phenols and ethoxylated alcohols, imidazolines, aminosuccinic acid or their derivatives etc. A mixture of such rust inhibitors or inhibitors can be used. By the gross weight of the lubricating composition, when present in the lubricating composition as herein described, the total amount of the inhibitor can range from 2.0 wt % to 1.0 wt %.

[0124] 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, polyisobutylene, hydrogenated styrene-isoprene polymers, styrene / maleate copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, α-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkylstyrenes, hydrogenated alkenyl aryl conjugated diene copolymers, or mixtures thereof. Viscosity modifiers may include star polymers, and suitable examples are described in U.S. Publication No. 2012 / 0101017A1.

[0125] In addition to or in lieu of a viscosity modifier, the electric motor lubricating fluids described herein may optionally contain one or more dispersant viscosity modifiers. Suitable dispersant viscosity modifiers may include functionalized polyolefins, for example, ethylene-propylene copolymers functionalized with the reaction product of an acylating agent (such as maleic anhydride) and an amine; polymethacrylates functionalized with amines; or esterified maleic anhydride-styrene copolymers reacted with amines.

[0126] The total amount of viscosity modifier and / or dispersant viscosity modifier, when present, may be up to about 1.0 wt%, or up to about 0.5 wt%, or up to about 0.3 wt%, based on the total weight of the lubricating and cooling fluid.

[0127] Demulsifiers: Demulsifiers include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof, including polyethylene oxide, polypropylene oxide, and (ethylene oxide-propylene oxide) polymers. When present, the amount of demulsifier in the lubricating and cooling fluid may be up to about 0.05 weight percent, or up to about 0.02 weight percent, or less than about 0.015 weight percent, based on the total weight of the lubricating and cooling fluid.

[0128] Antifoaming agents: Antifoaming agents used to reduce or prevent the formation of stable foam include silicones, polyacrylates, or organic polymers. Foam suppressors useful in the disclosed compositions of the present invention include polysiloxanes, copolymers of ethyl acrylate and 2-ethylhexyl acrylate, and optionally vinyl acetate. When present, the amount of antifoaming agent in the lubricating and cooling fluid can be up to about 0.1% by weight, or up to about 0.05% by weight, or less than about 0.04% by weight, based on the total weight of the lubricating and cooling fluid.

[0129] Pour point depressants: The electric motor lubricating fluid may optionally contain one or more pour point depressants. Suitable pour point depressants may include maleic anhydride-styrene esters, polymethacrylates, polymethyl methacrylates, polyacrylates, or polyacrylamides, or mixtures thereof. Pour point depressants, when present, may be present in an amount of about 0.001% to about 0.04% by weight, based on the total weight of the lubricant.

[0130] In general, the lubricating and cooling fluids described herein may include additive components within the ranges listed in Table 2.

[0131] Table 2

[0132] Components Weight % (suitable embodiment) Weight % (preferred embodiment) Relatively high molecular weight succinimide dispersant 1.0-8.0 2.0-4.0 Optional other dispersants 0-5.0 0-2.0 Vulcanized components 0.05-1.5 0.2-1.0 Amine salts of phosphate esters 0.3-0.7 0.4-0.6 Oil-soluble phosphorus antiwear additives 0.05-1.5 0.05-0.5 detergent 0.05-0.5 0.1-0.3 antioxidants 0.1-0.6 0.3-0.5 defoaming agent 0-0.05 0.1-0.04 Viscosity index improvers 0-7.0 0-5.0 base oil margin margin total 100 100

[0133] The percentages of each component above represent the weight percentage of each component based on the total weight of the lubricating and cooling fluid containing the component. The additives used to formulate the compositions described herein can be blended into the base oil individually or in various subcombinations. However, it may be appropriate to use an additive concentrate (i.e., additives plus a diluent, such as a hydrocarbon solvent) to blend all components simultaneously. The use of an additive concentrate takes advantage of the mutual compatibility provided by the combination of ingredients in the form of an additive concentrate. In addition, the use of a concentrate reduces blending time and reduces the possibility of blending errors.

[0134] As described above, additive concentrates containing a relatively high molecular weight succinimide dispersant, an amine salt of a phosphate ester, an ashless dialkyl dithiophosphate, and a thiadiazole or derivative thereof have a much higher viscosity than is typically used in automotive lubricants having a kV100°C viscosity of about 4.5 cSt or less, about 3.5 cSt or less, or about 3.0 cSt or less. In some approaches, the additive concentrates herein of such components have a kV100°C of about 15 cSt to about 80 cSt, but when used in a finished fluid having the described elemental relationships, the electric motor lubricating fluids herein still have a finished kV100°C of about 4.5 cSt or less, about 3.5 cSt or less, or about 3.0 cSt or less, while having improved wear performance, electrical conductivity, and oxidation stability. In some embodiments, the ratio of the kV100°C of the additive concentrate to the kV100°C of the finished fluid is from about 5:1 to about 30:1. Any embodiment of the electric motor lubricating fluid herein exhibits only a slight change in viscosity after aging, such as a viscosity change of about 0.10 cSt or less (e.g., 0.01 cSt to 0.1 cSt, or 0.04 cSt to 0.08 cSt) after aging 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 load-to-failure rating of at least 8 in the FZG A10 / 16.6R / 90 Scuff Resistance 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 nS / M to about 60 nS / M), as measured using an electric motor lubricating fluid according to a modified conductivity test of ASTM D2624-15 and measured using a Fluconepsilon tester or equivalent at 20 Hz and about 100° C. Surprisingly, such low viscosity fluids with low conductivity and high oxidative stability can achieve the above-mentioned acceptable performance in the FZG A10 / 16.6R / 90 Scuff Test of CEC L-84-02.

[0135] Example

[0136] The present disclosure and its many advantages may be better understood by the following examples. The following examples are illustrative and do not limit the scope or spirit thereof. Those skilled in the art will readily appreciate that variations of the components, methods, steps, and apparatus described in these examples may be used. Unless otherwise indicated or apparent from the context of the following examples and the discussion throughout this disclosure, all percentages, ratios, and parts mentioned in this disclosure are by weight.

[0137] To demonstrate how high molecular weight dispersants can be used in low viscosity fluids to achieve tested wear performance and conductivity, this paper systematically compares fluids with various elemental relationships of nitrogen, boron, sulfur, and / or phosphorus to evaluate the wear performance, oxidation 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. The formulations were evaluated for FZG scuff resistance, oxidative viscosity stability, and conductivity.

[0138] The FZG anti-scuffing test is used to evaluate the anti-scuffing load capacity of lubricants and is performed according to the A10 / 16.6R / 90 test of CEC L-84-02. The results are reported as failure load levels, and better results are obtained for samples with higher failure load levels.

[0139] Oxidative viscosity stability measures the difference between the initial and final viscosity of a fluid after aging for 192 hours at 170°C to 180°C according to CEC L-48-A-00, where the fluid of this example was aged at 170°C. Lower values indicate improved performance. Thus, fluids with high oxidative stability exhibit only small changes in viscosity measured before and after aging.

[0140] It is beneficial for the electric motor fluid to exhibit low conductivity.The conductivity of the fluid is measured according to a modified version of ASTM D2624-15 (testing lubricants rather than fuels using a Flucon Epsilon+ at 1.5 V, 20 Hz and 100°C).

[0141] The inventive and comparative formulations tested in Table 3 below all contained varying amounts of sulfurized components, phosphorus additives, detergents, and dispersants, as shown in Table 3. Each fluid also contained the same antioxidant, defoamer, and process oil. The antioxidant and defoamer were added to each fluid at the same treat 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 contained similar additives to the comparative formulations, but balanced the delivery of sulfur, phosphorus, and dispersants differently to achieve surprisingly improved wear performance, oxidation stability, and lubricant conductivity. Details of these components are as follows:

[0142] ● Sulfur component (S-1) : 2,5-dimercapto-1,3,4-thiadiazole and / or its derivatives containing about 35% by weight of sulfur, which are 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-

[0143] A 75:25 to 85:15 mixture of (nonyldithio)-1,3,4-thiadiazole.

[0144] ● Dispersant 1 (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, phosphorous acid, and boric acid. The dispersant has approximately 0.76% by weight phosphorus, approximately 0.35% by weight boron, and approximately 1.75% by weight nitrogen.

[0145] ● Dispersant 2 (Disp-2) : A phosphated and borated succinimide dispersant derived from 2100Mn polyisobutylene, maleic anhydride, a mixture of polyalkylene polyamines having an average of 6.5 nitrogen atoms per molecule, phosphorous acid, and boric acid. The dispersant has approximately 0.77% nitrogen, about 0.15% boron, and about 0.35% phosphorus by weight.

[0146] ● Phosphorus Additive 1(P-1) : Amine salts of phosphate esters, including dihexyl phosphate and monohexyl phosphate with C 12 to C 14 A mixture of dialkylated amines and / or trialkylated amines of alkyl groups. The phosphorus source comprises about 2.5 weight percent nitrogen and about 4.9 weight percent phosphorus.

[0147] ● Phosphorus Additive 2 (P-2) : Ashless dialkyl dithiophosphates including at least 3-[[bis(2-methylpropoxy)phosphonyl]thio]-2-methylpropanoic acid.

[0148] ● Detergent Additive 1 (Det-1) : A neutral calcium sulfonate having a TBN of about 25 to about 30 and about 2.6 wt% calcium.

[0149] All fluids tested herein comprised the same blend of Group III and Group IV base oils. As shown in the table below, all inventive examples exhibited improved anti-wear performance, electrical conductivity, and oxidation stability compared to comparative examples that delivered too little or too much phosphorus and included relatively low molecular weight dispersant additives. All fluids were considered low viscosity fluids, with a kV100°C (ASTM D445) of approximately 4.5 cSt or less.

[0150] Table 3: Fluid composition

[0151]

[0152] Measured according to ASTM D445 - kV 100°C

[0153] Table 4: Elemental analysis of fluids (calculated)

[0154] Invention Example 1 Invention Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Total phosphorus, ppm 180 238 271 147 160 247 172 Phosphorus from dispersant, ppm 76 112 152 35 76 76 76 Phosphorus from P-1, ppm 59 59 59 59 30 118 44 Phosphorus from P-2, ppm 54 54 54 54 54 54 54 Nitrogen from dispersant, ppm 167 249 350 77 175 175 175 Boron from dispersant, ppm 32 47 70 15 35 35 35 Sulfur, ppm 875 875 875 875 875 875 875

[0155] Table 5: Fluid properties

[0156] Invention Example 1 Invention Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 FZG, breaking load level** 8 9 5 7 5 6 8 ΔViscosity, cSt*** 0.04 0.08 0.05 0.06 0.17 0.13 0.16 Conductivity, nS / m**** 22 58 71 13 36 38 37

[0157] **CEC L-84-022(A10 / 16.6R / 90)

[0158] ***Difference between initial and final viscosity after aging measured according to CEC L-48-A

[0159] ****ASTM D2624-15 (20 Hz, 100°C) performed on a Flucon epsilon or equivalent tester

[0160] It should be understood that while the lubricating compositions and compositions of the present disclosure have been described in conjunction with the detailed description and summary herein, the foregoing description is intended to illustrate and not to limit the scope of the disclosure, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are also within the scope of the claims. It is intended that the specification and examples be considered merely exemplary, with the true scope of the disclosure being indicated by the appended claims.

[0161] After considering the practice of this specification and the embodiments disclosed herein, other embodiments of the present disclosure will be apparent to those skilled in the art. As used throughout the specification and claims, "one / one (kind) (a)" and / or "one / one (kind) (an)" may refer to one or more than one. Unless otherwise indicated, all numerals expressing the amount of components, characteristics used in this specification, such as molecular weight, percentage, ratio, reaction conditions, etc., should be understood to be modified by the term "about" in all cases, regardless of whether the term "about" exists. Therefore, unless otherwise indicated, the numerical parameters set forth in this specification are approximate values that may vary depending on the desired characteristics attempted to be obtained by the present disclosure. Minimally, and without attempting to limit the scope of the application of the doctrine of equivalents to the claims, each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying general rounding techniques. Although the numerical range and parameters setting forth the wide range of the present disclosure are approximate values, the numerical values set forth in the specific embodiments are reported as accurately as possible. However, any numerical value inherently contains some errors that are inevitably caused by the standard deviation found in its corresponding test measurement value.

[0162] It should be understood that each component, compound, substituent or parameter disclosed herein should be interpreted as disclosed for use alone or in combination with one or more of each other component, compound, substituent or parameter disclosed herein.

[0163] It should be further understood that each range disclosed herein is to be interpreted as a disclosure of each specific value within the disclosed range having the same number of significant figures. Thus, a range of 1-4 is to be interpreted as an explicit disclosure of the values 1, 2, 3, and 4, as well as any range of these values, e.g., 1-4, 1-3, 1-2, 2-4, 2-3, etc.

[0164] It should be further understood that each lower limit of each range disclosed herein should be interpreted as disclosed in combination with each upper limit of each range disclosed herein for the same component, compound, substituent or parameter and each specific value within each range. Therefore, this disclosure should be interpreted as a disclosure of all ranges derived by combining each lower limit of each range with each upper limit of each range or with each specific value within each range, or by combining each upper limit of each range with each specific value within each range.

[0165] In addition, a particular amount / value of a component, compound, substituent or parameter disclosed in this specification or the examples should be interpreted as a disclosure of the lower or upper limit of a range, and thus can be combined with any other lower or upper limit or particular amount / value of a range for the same component, compound, substituent or parameter disclosed elsewhere in this disclosure to form a range for that component, compound, substituent or parameter.

Claims

1. An electric motor lubricating fluid suitable for use in an electric or hybrid electric vehicle, the electric motor lubricating fluid comprising: one or more base oils of lubricating viscosity; from about 2 weight percent to about 4 weight percent of a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 2,000 or greater; an amine salt of a phosphate ester, the amine salt of the phosphate ester providing about 40 ppm to about 70 ppm of phosphorus to the electric motor lubricating fluid; an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, the oil-soluble phosphorus antiwear additive providing from about 40 ppm to about 70 ppm phosphorus to the electric motor lubricating fluid; a sulfur-donating additive comprising a thiadiazole or a derivative thereof, said sulfur-donating additive providing up to 950 ppm of sulfur to said electric motor lubricating fluid; and wherein the electric motor lubricating fluid has a kV100°C of about 4.5 cSt or less and about 150 ppm to about 250 ppm total phosphorus.

2. The electric motor lubricating fluid of claim 1 , wherein the amine salt of the phosphate ester has a structure of Formula I or a solvate or hydrate thereof: in R1 and R2 are independently hydrogen or a linear, branched or cyclic hydrocarbon 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.

3. The electric motor lubricating fluid of claim 2, wherein R1 and R2 are independently C3 to C 10 an alkyl group, and wherein at least one of R3, R4, R5 and R6 is C 10 to C 20 Alkyl group.

4. The electric motor lubricating fluid of claim 1 , wherein the high molecular weight polyisobutylene has a number average molecular weight of about 2,000 to about 2,300.

5. The electric motor lubricating fluid of claim 4, wherein the succinimide dispersant has from about 0.5 wt% to about 1 wt% nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers from about 70 ppm to about 140 ppm phosphorus and from about 150 ppm to about 300 ppm nitrogen to the electric motor lubricating fluid.

6. The electric motor lubricating fluid of claim 1 , wherein the succinimide dispersant, the amine salt of the phosphate ester, the ashless dialkyl dithiophosphate, and the thiadiazole or derivative thereof are provided in an additive concentrate, and wherein the additive concentrate has a kV100° C. of about 15 cSt to about 80 cSt.

7. The electric motor lubricating fluid of claim 6, wherein 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.

8. The electric motor lubricating fluid of claim 1, wherein the electric motor lubricating fluid exhibits a viscosity change of less than 0.09 cSt after aging in accordance with CECL-48-A).

9. The electric motor lubricating fluid of claim 1, wherein the electric motor lubricating fluid achieves a failure load rating of at least 8 in the FZG A10 / 16.6R / 90 Scuff Resistance Test of CEC L-84-02.

10. The electric motor lubricating fluid of claim 1 , wherein the electric motor lubricating fluid has an electrical conductivity of about 60 nS / M or less as measured using the electric motor lubricating fluid according to a modified electrical conductivity test of ASTM D2624-15 and measured at 20 Hz and 100° C.

11. The electric motor lubricating fluid of claim 1 , wherein the oil-soluble phosphorus antiwear additive comprising the ashless dialkyl dithiophosphate is prepared 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 the ashless dialkyl dithiophosphate.

12. The electric motor lubricating fluid of claim 1 , wherein the ashless dialkyl dithiophosphate comprises a compound of formula II or a salt thereof: wherein R7 and R8 are independently C3 to C8 linear or branched alkyl groups, and R9 is -H or -CH3.

13. The electric motor lubricating fluid of claim 12, wherein the ashless dialkyl dithiophosphate is 3-[[bis(2-methylpropoxy)phosphonothioyl]thio]-2-methyl-propionic acid.

14. The electric motor lubricating fluid of claim 1 , wherein the thiadiazole or derivative thereof comprises one or more compounds having the structure of Formula III: in Each R 10 independently hydrogen or sulfur; Each R 11 are independently alkyl groups; n is an integer of 0 or 1, and if R 10 is hydrogen, then the adjacent R 11 The integer n of the part is 0, and if R 10 is sulfur, then the adjacent R 11 Some of n is 1; and At least one of the R 10 It's sulfur.

15. The electric motor lubricating fluid of claim 1 further comprising one or more metal-containing detergent additives that provide no more than about 50 ppm of calcium to the electric motor lubricating fluid.

16. An additive concentrate suitable for use in an electric motor lubricating fluid, the additive concentrate comprising: from about 40% to about 70% by weight of a succinimide dispersant derived from a high molecular weight polyisobutylene having a number average molecular weight of about 2,000 or greater; an amine salt of a phosphate ester, the amine salt of the phosphate ester providing about 1000 ppm to about 1500 ppm of phosphorus to the additive concentrate; an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, the oil-soluble phosphorus antiwear additive providing from about 800 ppm to about 1300 ppm phosphorus to the additive concentrate; a sulfur-donating additive comprising a thiadiazole or a derivative thereof, said sulfur-donating additive providing sulfur to said additive concentrate, but not exceeding about 18,000 ppm of sulfur; and wherein the additive concentrate has a kV100°C of about 15 cSt to about 80 cSt.

17. The additive concentrate of claim 16, wherein the high molecular weight polyisobutylene has a number average molecular weight of about 2,000 to about 2,300.

18. The additive concentrate of claim 16, wherein the succinimide dispersant has from about 0.5 wt% to about 1 wt% nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers from about 70 ppm to about 140 ppm phosphorus and from about 150 ppm to about 300 ppm nitrogen to the electric motor lubricating fluid.

19. The additive concentrate of claim 16, further comprising one or more metal-containing detergent additives that provide no more than about 950 ppm of calcium to the additive concentrate.

20. A method for lubricating a powertrain component including an electric motor, the method comprising: lubricating the powertrain component with an electric motor lubricating composition, and wherein the electric motor lubricating composition contacts a portion of the electric motor; The electric motor lubricating composition comprises: (i) one or more base oils of lubricating viscosity; (ii) from about 2% by weight to about 4% by weight of a succinimide dispersant, the succinimide dispersant being derived from a high molecular weight polyisobutylene having a number average molecular weight of about 2,000 or greater; (iii) an amine salt of a phosphate ester, the amine salt of the phosphate ester providing from about 40 ppm to about 70 ppm of phosphorus to the electric motor lubricating fluid; (iv) an oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, the oil-soluble phosphorus antiwear additive providing from about 40 ppm to about 70 ppm of phosphorus to the electric motor lubricating fluid; and (v) a sulfur-donating additive comprising a thiadiazole or a derivative thereof, the sulfur-donating additive providing sulfur to the electric motor lubricating fluid, but not more than about 950 ppm of sulfur; and wherein the electric motor lubricating fluid has a kV100°C of about 3.5 cSt or less, about 150 ppm to about 200 ppm total phosphorus, and a conductivity of about 37 nS / M or less, as measured by using the electric motor lubricating fluid according to a modified conductivity test of ASTM D2624-15 and measured at 20 Hz and 100°C.

21. The method for lubricating a powertrain component including an electric motor according to claim 20, wherein the high molecular weight polyisobutylene has a number average molecular weight of about 2,000 to about 2,300.

22. The method for lubricating a powertrain component comprising an electric motor according to claim 20, wherein the succinimide dispersant has from about 0.5 wt% to about 1 wt% nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers from about 70 ppm to about 140 ppm phosphorus and from about 150 ppm to about 300 ppm nitrogen to the electric motor lubricating fluid.

23. The method for lubricating a powertrain component including an electric motor according to claim 20, wherein the succinimide dispersant, the amine salt of the phosphate ester, the oil-soluble phosphorus antiwear additive comprising an ashless dialkyl dithiophosphate, and the sulfur-donating additive comprising a thiadiazole or a derivative thereof are provided in an additive concentrate having a kV100°C of about 15 cSt to about 80 cSt.

24. The method for lubricating a powertrain component including an electric motor according to claim 23, wherein 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.

25. The method for lubricating a powertrain component including an electric motor according to claim 20, wherein the electric motor lubricating fluid exhibits a viscosity change of less than 0.09 cSt after aging according to CEC L-48-A.

26. The method for lubricating a drivetrain component including an electric motor according to claim 20, wherein the electric motor lubricating fluid achieves a failure load rating of at least 8 in the FZG A10 / 16.6R / 90 Scuff Resistance Test of CEC L-84-02.

27. The method for lubricating a driveline component comprising an electric motor according to claim 20, wherein the electric motor lubricating composition further comprises one or more metal-containing detergent additives that provide no more than about 50 ppm of calcium to the electric motor lubricating composition.

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