Lubricating fluid for electric motor system

Abstract

Provided herein is an electric motor driveline fluid for an electric motor system, the electric motor driveline fluid comprising a lubricating base oil, at least one sulfurizing component, and at least one dispersant derived from a polyisobutylene having a number average molecular weight of at least 2000. When selected elemental relationships of phosphorus, sulfur and calcium are included in the fluid, the electric motor driveline fluid provides acceptable wear performance for use in electric motor system fluids having low viscosity as well as good electrical conductivity and oxidation stability.

Description

Technical Field

[0001] The present disclosure relates to a lubricating fluid for an electric motor system and a method for lubricating a drive train in an electric motor system. In particular, the disclosed method and lubricating fluid relate to a relatively low viscosity lubricating fluid for use in an electric motor and / or drive train of an electric or hybrid electric vehicle, the relatively 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 electric vehicle powertrain lubricants are achieving acceptable wear performance and maintaining oxidation stability while ensuring compatibility of the lubricant with live components in the powertrain. Because lubricants in electric or hybrid electric vehicles may also contact components in the electric motor, the fluid's conductivity also needs to be relatively low to inhibit static electricity accumulation and discharge from live components.

[0003] To improve efficiency, lubricant manufacturers often seek lower lubricant viscosity, but lower viscosity fluids are often less than ideal for the harsh wear tests often required by industrial and / or automotive manufacturers. Therefore, lower viscosity fluids may often require additional anti-wear additives to meet the required wear tests. However, adding these additional additives often increases conductivity and / or reduces the oxidation stability or viscosity stability of the lubricant.

[0004] It is also common to include one or more friction modifiers in conventional transmission lubricants, especially for improving judder durability. However, lubricants used in electric vehicle drive trains tend to be negatively impacted by high levels of friction modifiers, which can interfere with the performance of other components in the lubricant, such as anti-wear additives. Therefore, in the case of lower viscosity lubricants configured for use in electric or hybrid electric vehicles, achieving desired performance in terms of anti-wear, oxidation stability, conductivity, corrosion and / or friction performance can be challenging. Summary of the invention

[0005] In one method or embodiment, an electric drive train fluid suitable for use in an electric or hybrid electric vehicle is described herein. In one aspect of the method or embodiment, the electric drive train fluid comprises: one or more base oils of lubricating viscosity; a succinimide dispersant derived from a polyisobutylene having a number average molecular weight of about 2000 or greater, wherein the succinimide dispersant has up 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 about 150 ppm to about 270 ppm of dispersant phosphorus (P) to the electric drive train fluid; a sulfur-donating additive comprising a thiadiazole or a derivative thereof, wherein the thiadiazole or a derivative thereof provides at least about 1000 ppm of thiadiazole to the electric drive train fluid; thiadiazole sulfide (S); wherein the combined dispersant phosphorus and thiadiazole sulfide (P+S) is at least about 1300 ppm, and wherein the weight ratio of the dispersant phosphorus to the thiadiazole sulfide (P / S) is at least about 0.1; a detergent system is provided in which one or more calcium-containing detergents are provided, and wherein the one or more calcium-containing detergents provide no more than about 200 ppm of calcium; no more than about 0.4 weight percent of a friction modifier; and wherein the electric powertrain fluid has a kV100 viscosity of about 3.2 cSt or greater, about 150 ppm to about 270 ppm of total phosphorus, and a conductivity of about 130 nS / M or less, the conductivity being measured using the electric powertrain fluid by a modified conductivity test according to ASTM D2624-15 and measured at 20 Hz and 170°C.

[0006] In other methods or embodiments, the electric powertrain fluid 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 friction modifier is an alkylimide, an alkylamine, a hydrocarbyl imidazole, a derivative thereof, or a combination thereof; and / or wherein the friction modifier comprises 0 wt % to about 0.4 wt % of one or more of a linear or branched C16 to C18 substituted succinic acid or anhydride reacted with an amine, a polyamine, or ammonia (preferably reacted with ammonia), 0 wt % to about 0.08 wt % of an ethoxylated alkylamine (preferably, an ethoxylated tallow amine) ; wherein the friction modifier is 0 wt % to about 0.1 wt % of a linear or branched C16 to C18 substituted succinic acid or anhydride reacted with an amine, polyamine or ammonia (preferably reacted with ammonia); and / or wherein the polyisobutylene has a number average molecular weight of about 2,000 to about 2,400; and / or wherein the electric motor lubricating fluid comprises about 2 wt % to about 8 wt % (preferably, about 4 wt % to about 8 wt %) of a succinimide dispersant; and / or wherein the electric drive train fluid has a viscosity change of less than about 0.5 cSt after the electric drive train fluid has been aged according to CEC L-48-A; and / or wherein the electric drive train fluid has a viscosity change of less than about 0.5 cSt after the electric drive train fluid has been aged according to CEC L-48-A L-84-02 achieves a failure load rating of at least about 8 in the FZGA10 / 16.6R / 120 rub resistance test; and / or wherein the thiadiazole or derivative thereof provides about 1500 ppm or less of sulfur; and / or wherein the combined dispersant phosphorus and thiadiazole sulfur (P+S) is about 1300 ppm to about 1400 ppm; and / or wherein the weight ratio of the dispersant phosphorus to the thiadiazole sulfur (P / S) is about 0.1 to about 0.3; and / or wherein about 90% to about 100% of the total phosphorus is provided by the succinimide dispersant; and / or wherein the amount of phosphorus provided is about 1 ppm of phosphorus per 8 to 13 number average molecular weight units of the polyisobutylene portion of the succinimide dispersant; and / or wherein the thiadiazole or derivative thereof comprises one or more compounds having the structure of Formula I:

[0007]

[0008] wherein each R of Formula III 10 is independently hydrogen or sulfur; each R of formula III 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 It's sulfur.

[0009] In another method or embodiment, a method for lubricating a drive train component including an electric motor is described herein. In various aspects of this embodiment, the method includes lubricating the drive train component with an electric drive train fluid, and in some embodiments, the electric drive train fluid contacts a portion of the electric motor. In other aspects of this embodiment, the electric drive train fluid comprises: (i) one or more base oils of lubricating viscosity; (ii) a succinimide dispersant derived from a polyisobutylene having a number average molecular weight of about 2000 or greater, wherein the succinimide dispersant has up to about 1 weight percent nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers about 150 ppm to about 270 ppm of dispersant phosphorus (P) to the electric drive train fluid; (iii) a sulfur-supplying additive including a thiadiazole or a derivative thereof, the thiadiazole or a derivative thereof providing at least about 1000 ppm (preferably about 1000 ppm to about 1400 ppm) of thiadiazole sulfur (S) to the electric drive train fluid, wherein the combined dispersant phosphorus and thiadiazole sulfur (P+S) is at least about 1300 ppm (preferably about 1300 ppm to about 1400 ppm), and wherein the weight ratio of the dispersant phosphorus to the thiadiazole sulfur (P / S) is at least about 0.1 (preferably about 0.1 to about 0.3); (iv) a detergent system providing one or more calcium-containing detergents, wherein the one or more calcium-containing detergents provide no more than about 200 ppm of calcium; and (v) no more than about 0.4 weight percent friction modifier; and wherein the electric powertrain fluid has a kV100 viscosity of about 3.2 cSt or greater, about 150 ppm to about 270 ppm total phosphorus, and a conductivity of about 130 nS / M or less, as measured using the electric powertrain fluid by a modified conductivity test according to ASTM D2624-15 and measured at 20 Hz and 170°C.

[0010] In further methods or embodiments, the method for lubricating a drive train component including an electric motor as described in the preceding paragraph may 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 friction modifier is an alkylimide, an alkylamine, a hydrocarbyl imidazole, a derivative thereof or a combination thereof; and / or wherein the friction modifier is 0 wt % to about 0.08 wt % of an ethoxylated alkylamine (preferably, an ethoxylated tallow amine); and / or wherein the organic friction modifier is 0 wt % to about 0.4 wt % of a linear or branched C16 to C18 substituted succinic acid or anhydride reacted with an amine, a polyamine or ammonia (preferably, reacted with ammonia); and / or wherein the polyisobutylene has a number average molecular weight of about 2,000 to about 2,400; and / or wherein the electric drive train fluid contains about 2 wt % to about 8 wt % (preferably, about 4 wt % to about 8 wt %) of a succinimide dispersant; and / or wherein the electric drive train fluid has been treated according to CEC The electric powertrain fluid has a viscosity change of less than about 0.5 cST after L-48-A aging; and / or wherein the electric powertrain fluid achieves a failure load rating of at least about 8 in the FZG A10 / 16.6R / 120 Scuff Test of CEC L-84-02; and / or wherein about 90% to about 100% of the total phosphorus is provided by the succinimide dispersant; and / or wherein the thiadiazole or derivative thereof comprises one or more compounds having the structure of Formula III:

[0011]

[0012] Each R 10 is 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 It's sulfur.

[0013] In yet other methods or embodiments, described herein is the use of an electric drive train fluid to achieve one or more of: (i) an electrical conductivity of about 130 nS / M or less, as measured using the electric drive train fluid by a modified conductivity test according to ASTM D2624-15 and measured at 20 Hz and 170° C.; (ii) a viscosity change of less than about 0.5 cST after the electric drive train fluid has been aged according to CEC L-48-A; and / or (iii) a failure load rating of at least about 8 in the FZG A10 / 16.6R / 120 Scuff Resistance Test of CEC L-84-02. In such embodiments, the electric drive train fluid comprises any of the embodiments described in the present disclosure and contains at least: (i) one or more base oils of lubricating viscosity; (ii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 2000 or greater, wherein the succinimide dispersant has up 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 about 150 ppm to about 270 ppm of dispersant phosphorus (P) to the electric drive train fluid; (iii) a sulfur-donating additive comprising a thiadiazole or a derivative thereof, the thiadiazole or derivative thereof providing at least about 1000 ppm (preferably about 1 000 ppm to about 1400 ppm) of thiadiazole sulfide (S), wherein the combined dispersant phosphorus and thiadiazole sulfide (P+S) is at least about 1300 ppm (preferably about 1300 ppm to about 1400 ppm), and wherein the weight ratio of the dispersant phosphorus to the thiadiazole sulfide (P / S) is at least about 0.1 (preferably about 0.1 to about 0.3); (iv) a detergent system providing one or more calcium-containing detergents, wherein the one or more calcium-containing detergents provide no more than about 200 ppm of calcium; and (v) no more than about 0.4 weight percent of a friction modifier; and wherein the electric powertrain fluid has a kV100 viscosity of about 3.2 cSt or greater, and about 150 ppm to about 270 ppm of total phosphorus.

[0014] 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.

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

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

[0017] 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.

[0018] 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 containing one or more halogen groups, hydroxyl groups, alkoxy groups, mercapto groups, nitro groups, nitroso groups, amino groups, pyridyl groups, furanyl groups, imidazolyl groups, oxygen and nitrogen substitutions, and wherein there are no more than two non-hydrocarbon substituents for every ten carbon atoms in the hydrocarbyl group.

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

[0020] The terms "soluble", "oil-soluble" or "dispersible" as used herein 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 oil to a sufficient extent to exert their intended effect in the environment in which the oil is employed. In addition, the additional incorporation of other additives may also allow for the incorporation of higher levels of a particular additive, if desired.

[0021] 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.

[0022] 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.

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

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

[0025] 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. The present disclosure also contemplates that any composition described using the terms "comprising," "including," "containing" is also to be interpreted as including disclosure of the same composition "consisting essentially of" or "consisting of" its specifically listed components. DETAILED DESCRIPTION

[0026] According to exemplary embodiments, described herein are lower viscosity driveline lubricants having selected element relationships suitable for electric or hybrid electric vehicles that surprisingly achieve passing performance in a demanding FZG wear resistance test (such as the A10 / 16.6R / 90 test of CEC L-84-02), while achieving good conductivity and maintaining oxidation stability. However, surprisingly with respect to the lubricating fluids herein, it was found that when such dispersants are used in combination with selected phosphorus, sulfur and calcium element relationships, a combination of certain additives (including a succinimide dispersant derived from polyisobutylene having a number average molecular weight of more than 2000) helps achieve passing wear, conductivity and oxidation performance. In some embodiments, it was also found that certain friction modifiers need to be limited in the composition.

[0027] When the selected succinimide dispersants herein are combined with other lubricant additives and have certain elemental relationships (e.g., relationships of phosphorus, sulfur, and / or calcium discussed more below) to form a finished lubricant, the finished lubricants herein achieve lower viscosity, tested anti-wear performance, suitable conductivity and / or oxidation stability, thereby making the fluid suitable for use in the powertrain of an electric or hybrid electric vehicle.

[0028] The fluids herein comprise at least: (i) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 2000 or greater, wherein the succinimide dispersant has up to about 1 weight percent nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers about 150 ppm to about 270 ppm of dispersant phosphorus (P) to the electric powertrain fluid; and (ii) a sulfur-donating additive comprising a thiadiazole or a derivative thereof, wherein the thiadiazole or a derivative thereof provides at least about 1000 ppm of thiadiazole sulfur (S) to the electric powertrain fluid. It was further found that in order to achieve performance for electric or hybrid electric vehicles, the combined amount of phosphorus delivered from the dispersant phosphorus and sulfur delivered from the thiadiazole or its derivative (P+S) needs to be at least about 1300 ppm (preferably, about 1300 ppm to about 2000 ppm, about 1300 ppm to about 1600 ppm, or about 1300 ppm to about 1400 ppm), and the weight ratio of phosphorus delivered from the dispersant phosphorus to sulfur delivered from the thiadiazole or its derivative (P / S) needs to be at least about 0.1 (preferably, about 0.1 to about 0.5, about 0.1 to about 0.4, or about 0.1 to about 0.3).

[0029] In addition, other embodiments of lubricants herein also include selected detergent systems and / or selected friction modifier systems to achieve performance suitable for hybrid and / or hybrid electric vehicles. In one embodiment, the lubricant herein also includes a detergent system that provides one or more calcium-containing detergents but only has a limited amount of calcium. Preferably, the detergent system includes one or more calcium-containing detergents that provide no more than about 200ppm of calcium. In other embodiments, the lubricant herein may also include a selected friction modifier system with no more than about 0.4% by weight of a friction modifier, the friction modifier comprising alkylamides, alkylimides, alkylamines, hydrocarbylamines, hydrocarbyl polyamines, hydrocarbyl imidazoles, their derivatives or combinations thereof. As discussed more below, the lubricant herein may only include a limited amount of ethoxylated alkylamine friction modifiers and / or a limited amount of alkylated succinic acid or anhydride or its derivatives. For example, the lubricants herein may contain less than 0.1 wt. % of an ethoxylated alkyl amine (preferably, ethoxylated tallow amine) and / or less than 0.3 wt. % of a friction modifier comprising an alkylated succinic acid or anhydride or derivatives thereof.

[0030] When the electric drive train fluids herein have a relatively low kV100 viscosity of about 3.2 cSt or higher (preferably, about 3.2 cSt to about 7 cSt) and about 150 ppm to about 270 ppm of total phosphorus in combination with the other components, relationships, and systems described above, the lubricant simultaneously exhibits low conductivity, tested anti-wear performance, and / or desirable oxidation stability. For example, the fluids herein exhibit one or more of the following: (i) a conductivity of about 130 nS / M or less, as measured using the electric drive train fluid by the modified conductivity test according to ASTM D2624-15 and measured at 20 Hz and 170° C.; (ii) a viscosity change of less than about 0.5 cSt after the electric drive train fluid has been aged according to CEC L-48-A; and / or (iii) a failure load rating of at least about 8 in the FZG A10 / 16.6R / 120 Scuff Resistance Test of CEC L-84-02. Each component additive, relationship and system is further described below.

[0031] Succinimide dispersant :

[0032] The electric motor drive train fluid herein comprises a dispersant system having at least one oil-soluble ashless dispersant, which is preferably a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 2000 or greater and further post-treated with a phosphorus-containing compound and a boron-containing compound. The succinimide dispersant herein may be derived from a hydrocarbyl-substituted dicarboxylic acid or anhydride reacted with a polyalkylene polyamine. Succinimide dispersants and their preparation are disclosed in at least US 7,897,696 and / or US 4,234,435, which are incorporated herein by reference.

[0033] The hydrocarbyl portion of the hydrocarbyl dicarboxylic acid or anhydride may be derived from a polymer of butene, 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 polyisobutylenes prepared using a BF3 catalyst.

[0034] The number average molecular weight of the polyisobutylene substituent of the dispersant herein can vary from at least about 2000, and in some cases up to about 3000, as determined by gel permeation chromatography (GPC) using polystyrene (having a number average molecular weight of 180 to about 18,000) as a calibration reference. The GPC method additionally provides weight average molecular weight distribution information; see, e.g., WW Yau, JJ Kirkland, and DD Bly, "Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New York, 1979, which is also incorporated herein by reference.

[0035] The polyisobutylene portion of the dispersant 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 referred to as a 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.

[0036] The dicarboxylic acid or anhydride suitable for forming the dispersant of this article can be selected from carboxylic acid reactants, such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethyl maleic anhydride, dimethyl maleic anhydride, ethyl maleic acid, dimethyl maleic acid, hexyl maleic acid, etc., including corresponding acid halides and C1-C4 aliphatic esters. In some methods, the molar ratio of the dicarboxylic acid or anhydride to the hydrocarbyl part in the reaction mixture for preparing the hydrocarbyl-dicarboxylic acid or anhydride can be widely varied. Therefore, the feed molar ratio can be changed from 5:1 to 1:5, for example, from 3:1 to 1:3. In some embodiments, the particularly suitable molar ratio of acid or anhydride to the hydrocarbyl part 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 from 1:1 to 1.5:1, or from 1:1 to 1.4:1, or from 1.1:1 to 1.3:1, or from 1:1 to 1.2:1.

[0037] Any of many polyalkylene polyamines can be used as a dispersant additive for preparing the present invention. 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 in its entirety. 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 in the present disclosure described herein can be the reaction product of polyisobutenyl succinic anhydride (PIBSA) and a polyamine, such as 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.

[0038] As mentioned above, the succinimide dispersant of this article can be post-treated with a boron compound. Suitable boron compounds that can be used to form the dispersant of this article include any boron compound or mixture of boron compounds that can introduce boron-containing substances into the ashless dispersant. Any organic or inorganic boron compound that can carry out this reaction can be used. Therefore, boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF4 boric acid such as borous acid (for example, alkyl-B (OH) 2 or aryl-B (OH) 2), boric acid (i.e. H3BO3), tetraboric acid (i.e. H2B5O7), metaboric acid (i.e. HBO2), ammonium salts of such boric acids and esters of such boric acids can be used. The use of a complex of a trihalide boron with an ether, an organic acid, an inorganic acid or a hydrocarbon is a convenient method for introducing a boron reactant into a 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.

[0039] The succinimide dispersants herein may 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 materials into the ashless dispersant. Thus, any organic or inorganic phosphorus compound capable of such a reaction may be used. Thus, such inorganic phosphorus compounds 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 phosphites, thiophosphorous acid, dithiophosphorous acid and trithiophosphorous acid; trihydrocarbyl phosphine oxides; trihydrocarbyl phosphine sulfides; monohydrocarbyl phosphonates and dihydrocarbyl phosphonates (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; monohydrocarbyl phosphites and dihydrocarbyl phosphonites (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 depicted as H2(HPO3), sometimes referred to as o-phosphorous acid or phosphonic acid), phosphoric acid (H3PO4, sometimes referred to as orthophosphoric acid), hypophosphorous acid (H4P2O6), metaphosphoric acid (HPO3), pyrophosphoric acid (H4P2O7), hypophosphorous acid (H3PO2, sometimes referred to as phosphinic acid), pyrophosphorous acid (H4P2O5, sometimes referred to as pyrophosphonic acid), phosphinic acid (H3PO), tripolyphosphoric acid (H5P3O10), tetrapolyphosphoric acid (H5P4O13), trimetaphosphoric acid (H3P3O9), phosphorus trioxide, phosphorus tetroxide, phosphorus pentoxide, and the like may be used. 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 referred to as P4S10), can also be used to form the dispersant of the present disclosure. Inorganic phosphorus halides, such as PCl3, PBr3, POCl3, PSCl3, etc. can also be used.

[0040] Likewise, organophosphorus compounds may be used, such as monoesters, diesters, and triesters of phosphoric acid (e.g., trihydrocarbyl phosphates, dihydrocarbyl monoacid phosphates, 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 all-sulfur or partially-sulfur analogs of any of the foregoing organophosphorus compounds, and the like, 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.

[0041] In one embodiment, the succinimide dispersant of the fluids herein comprises at least a polyisobutylene moiety having a number average molecular weight of at least about 2000 (in other approaches, from about 2000 to about 3000, or in further 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 a polyisobutylene moiety having a number average molecular weight between 2000 and 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.

[0042] In some embodiments, the dispersants described herein comprise about 2 wt % to about 8 wt % (preferably, about 4 wt % to about 8 wt %) of an electric motor drive train fluid and deliver about 300 ppm to about 600 ppm of nitrogen, about 150 ppm to about 270 ppm of phosphorus, and about 50 ppm to about 120 ppm of boron to the finished fluid. As shown in the examples below, when such succinimide dispersants are combined with other fluid components, particularly selected amounts of sulfur, boron, nitrogen, and / or phosphorus, the lubricant achieves tested wear and conductivity performance and oxidation stability suitable for use in a lubricant in an electric and / or hybrid electric vehicle drive train or powertrain.

[0043] Sulfur supply additives :

[0044] The electric motor drive train fluid also contains a sulfur-donating additive in an amount that improves wear performance, conductivity, and oxidative stability when combined with the above-mentioned succinimide. In the methods or embodiments herein, the sulfur-donating additive can be one or more thiadiazole compounds or hydrocarbyl-substituted derivatives thereof in an amount that provides at least about 1000 ppm of sulfur (preferably, about 1000 ppm to about 1500 ppm of sulfur, more preferably, about 1000 ppm to about 1400 ppm of sulfur, and most preferably, about 1000 ppm to about 1300 ppm of sulfur) to the lubricating fluid herein. In other methods, the sulfur-donating compound can be a mixture of thiadiazole compounds and / or hydrocarbyl-substituted derivatives thereof. Examples of thiadiazole compounds that can be used include, but are not limited to, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercapto-5-alkylthio-1,3,4-thiadiazole, 2-mercapto-5-alkyldithio-1,3,4-thiadiazole, 2,5-bis(alkylthio)-1,3,4-thiadiazole or 2,5-bis(alkyldithio)-1,3,4-thiadiazole. 1,3,4-thiadiazole is generally synthesized from hydrazine and carbon disulfide by known methods. See, for example, US2,765,289; US2,749,311; US2,760,933; US2,850,453; US2,910,439; US3,663,561; US3,862,798; and US3,840,549.

[0045] In some embodiments, the form and amount of the sulfur supplying additives herein contribute to the ability of the fluid to maintain low conductivity and oxidation stability while meeting other desired wear performance characteristics. In each method, the thiadiazole or derivative thereof includes one or more compounds having the structure of Formula III:

[0046]

[0047] wherein each R1 of Formula III is independently hydrogen or sulfur, each R2 of Formula III is independently an alkyl group, n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, the n of the adjacent R2 moiety is 1, and 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:

[0048]

[0049] wherein in Formula IIIa, each integer n is 1, each R1 is sulfur, each R2 is a C5 to C15 alkyl group, preferably a C8 to C12 alkyl group; and

[0050]

[0051] Wherein in formula IIIb, one integer n is 1, the associated R2 group is a C5 to C15 alkyl group (preferably a C8 to C12 alkyl group), and the other integer n is 0, and both R1 groups are sulfur. In some embodiments, the first 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-dithiol 1,3,4-thiadiazole, which includes 2,5-bis-(nonyl disulfide)-1,3,4-thiadiazole (such as, about 75% to about 90%) and 2,5-mono-(nonyl disulfide)-1,3,4-thiadiazole (such as about 10% to about 25%).

[0052] The thiadiazole compound or its hydrocarbyl substituted derivative is present in the electric motor lubricating fluid herein in an amount to deliver at least about 1000 ppm of sulfur, at least about 1100 ppm of sulfur, or at least about 1200 ppm of sulfur. In an embodiment, the thiadiazole compound or its hydrocarbyl substituted derivative is present in the electric motor lubricating fluid herein in an amount to deliver about 1000 ppm to about 1500 ppm of sulfur (in other embodiments, about 1000 ppm to about 1400 ppm of sulfur, or about 1000 ppm to about 1300 ppm of sulfur). In one embodiment, the thiadiazole compound is 2,5-dimercapto-134-thiadiazole, and the thiadiazole compound or its hydrocarbyl substituted derivative is present in the lubricating fluid in an amount to deliver about 1000 ppm to about 1300 ppm of sulfur (or other ranges therein).

[0053] Friction modifiers :

[0054] In some embodiments, the electric motor drive train fluids herein contain only low levels of friction modifiers, particularly no more than about 0.4 wt % friction modifiers. Herein, the electric motor drive train fluids contain less than about 0.4 wt % friction modifiers, which include alkylamides, alkylimides (having one or more alkyl C15-C30 alkyl chains), alkylamines, hydrocarbylamines, hydrocarbylpolyamines, hydrocarbylimidazoles, their derivatives, or combinations thereof. In one embodiment, the electric drive train fluids herein may have friction modifiers, but no more than about 0.3 wt % of linear or branched C16 to C18 substituted succinic acid or anhydride reacted with ammonia. In another embodiment, the electric powertrain fluid herein may contain no more than about 0.3 wt % of a linear or branched C16 to C18 substituted succinic acid or anhydride reacted with an amine, polyamine or ammonia, and / or 0 wt % to about 0.05 wt % of an alkyl or alkenyl substituted imidazoline, and / or 0 wt % to about 0.08 wt % of an ethoxylated alkyl amine (preferably, ethoxylated tallow amine).

[0055] In other embodiments, the electric drive train fluids herein may have no more than about 0.10 wt % friction modifiers, including linear or branched C16 to C18 substituted succinic acid or anhydride friction modifiers or derivatives thereof obtained by reaction with amines, polyamines or ammonia (preferably, with ammonia) and / or less than about 0.05 wt % alkyl or alkenyl substituted imidazolines. In other embodiments, the electric drive train fluids herein may have no more than about 0.30 wt % friction modifiers, including linear or branched C16 to C18 substituted succinic acid or anhydride friction modifiers or derivatives thereof obtained by reaction with amines, polyamines or ammonia and / or less than about 0.08 wt % ethoxylated tallow alkylamines.

[0056] In other embodiments, the limited amount of friction modifiers in the lubricants herein may also include low amounts of any metal-containing and / or low amounts of organic or metal-free friction modifiers, and only include low amounts of such friction modifiers, including imidazolines, amides, amines, succinimides, alkoxylated amines, alkoxylated ether amines, amine oxides, amidoamines, nitriles, betaines, quaternary ammoniums, imides, amine salts, aminoguanidines, alkanolamides, 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 and one or more aliphatic or aromatic carboxylic acids, etc.

[0057] The friction modifiers that tend to be limited in the electric powertrain lubricants of this article may contain a hydrocarbyl group selected from a linear, branched or aromatic hydrocarbyl group or a mixture thereof, and such hydrocarbyl groups 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.

[0058] Other friction modifiers that tend to be limited in the lubricants herein 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 polar end groups (e.g., carboxyl or hydroxyl groups) covalently bonded to oleophilic hydrocarbon chains. An example of an organic ashless and nitrogen-free friction modifier is generally known as glyceryl monooleate (GMO), which may contain monoesters, diesters, and triesters of oleic acid. Other suitable friction modifiers are described in U.S. Pat. No. 6,723,685.

[0059] Amine friction modifiers may also be limited in the lubricants herein, and such friction modifiers may include amines or polyamines. Such compounds may have straight-chain saturated or unsaturated hydrocarbon groups or mixtures thereof, and may contain 12 to 25 carbon atoms. Other examples of suitable friction modifiers include alkoxylated amines and alkoxylated ether amines. Such compounds may have straight-chain, saturated or unsaturated hydrocarbon groups, or mixtures thereof. It may contain from about 12 to about 25 carbon atoms. Examples include ethoxylated amines and ethoxylated ether amines. Amines and amides may be used as is or in the form of adducts or reaction products with boron compounds such as boron oxide, boron halides, metaborates, boric acid or monoalkyl, dialkyl or trialkyl borate. Other suitable friction modifiers are described in U.S. Pat. No. 6,300,291.

[0060] In any embodiment herein, the lubricant herein includes no more than about 0.4 wt% of total friction modifiers (if any), particularly no more than about 0.4 wt% of friction modifiers of the above types. In some embodiments, the lubricant herein is substantially free of or preferably free of friction modifiers, meaning that the lubricant has no more than about 0.4 wt% of such friction modifiers, no more than about 0.2 wt% of friction modifiers, no more than about 0.1 wt% of friction modifiers, no more than about 0.08 wt% of friction modifiers, no more than about 0.06 wt% of friction modifiers, no more than about 0.04 wt% of friction modifiers, no more than about 0.02 wt% of friction modifiers, no more than about 0.01 wt% of friction modifiers, or no functional amount of the above friction modifiers.

[0061] base oil :

[0062] The electric motor transmission fluid of this article comprises one or more base oils with lubricating viscosity. The base oil suitable for preparing the electric motor lubricating fluid used in the electric and / or hybrid electric motor vehicle according to the present disclosure can be selected from any of a suitable synthetic or natural oil or a mixture thereof with a 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 D445, the base oil may have a kinematic viscosity of about 2 cSt to about 6 cSt at 100°C.

[0063] The base oil used in the present invention as described herein 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 Groups III to IV specified in the American Petroleum Institute (API) Base Oil Interchangeability Guide. These base oil groups are shown in Table 1 below:

[0064] Table 1

[0065]

[0066] In one variant, the base oil may be selected from an API Group III base oil, or an API Group IV base oil, or a mixture of these base oils. Alternatively, the base oil may be a mixture of two or more of the API Group III base oils or two or more of the API Group IV base oils.

[0067] API Group III base oils may include oils derived from Fischer-Tropsch hydrocarbons. Fischer-Tropsch hydrocarbons are prepared 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 typically referred to as gas-to-liquids (GTL). For example, hydrocarbons may be hydroisomerized using the methods disclosed in U.S. Patent Nos. 6,103,099 or 6,180,575; hydrocracking and hydroisomerization using the methods disclosed in U.S. Patent Nos. 4,943,672 or 6,096,940; dewaxing using the methods disclosed in U.S. Patent No. 5,882,505; or hydroisomerization and dewaxing using the methods disclosed in U.S. Patent Nos. 6,013,171; 6,080,301; or 6,165,949.

[0068] API IV Group base oils, PAOs are typically derived from monomers having 4 to 30, or 4 to 20, or 6 to 16 carbon atoms. Examples of PAOs that can be used in the present invention include those derived from octene, decene, mixtures thereof, and the like. As measured by ASTM D2270-10, the PAO may have a kinematic viscosity of 2 to 15, or 3 to 12, or 4 to 8 cSt at 100°C. Examples of PAOs include 4 cSt PAOs at 100°C, 6 cSt PAOs at 100°C, and mixtures thereof.

[0069] The base oil is combined with an additive composition as disclosed in the embodiments herein to provide a lubricant 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 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.

[0070] Other additives :

[0071] In addition to the components described above, the electric motor drive train fluids described herein may also contain other additives of the type used in electric motor 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.

[0072] Antioxidants: In some embodiments, the electric motor drive train fluid contains one or more antioxidants. Suitable antioxidants include phenolic antioxidants, aromatic amine antioxidants, sulfur-containing antioxidants, and organic phosphites, among others.

[0073] 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) and 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 diphenylamine. Examples include hindered tert-butylated phenols, bisphenols and cinnamic acid derivatives and combinations thereof.

[0074] Aromatic amine antioxidants include, but are not limited to, diarylamines having the formula:

[0075]

[0076] wherein R' and R" each independently represent a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. Examples of the substituent of the aryl group include an aliphatic hydrocarbon group such as an alkyl group having 1 to 30 carbon atoms, a hydroxyl group, a halogen group, a carboxylic acid or ester group, or a nitro group.

[0077] 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 diphenylamine and dialkylated diphenylamine.

[0078] 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, benzene-α-naphthylamine, monooctylbenzene-α-naphthylamine, benzene-β-naphthylamine, monoheptyldiphenylamine, diheptyldiphenylamine, para-oriented styrenated diphenylamines, mixed butyloctyldiphenylamines, and mixed octylstyryldiphenylamines.

[0079] Sulfur-containing antioxidants include, but are not limited to, sulfurized olefins, characterized by the type of olefin used in their production and the final sulfur content of the antioxidant. High molecular weight olefins (i.e., those olefins having an average molecular weight of 168 g / mol to 351 g / mol) are preferred. Examples of usable olefins include alpha-olefins, isomerized alpha-olefins, branched olefins, cyclic olefins, and combinations of these.

[0080] Alpha-olefins include, but are not limited to, any C4 to C25 alpha-olefins. The alpha-olefins may be isomerized prior to or during the sulfurization reaction. Structural and / or conformational isomers of alpha-olefins containing internal double bonds and / or branches may also be used. For example, isobutylene is the branched olefin counterpart of the alpha-olefin 1-butene.

[0081] 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.

[0082] 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 seed oil, tallow, and combinations of these.

[0083] The total amount of antioxidant in the lubrication 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 up to about 100 ppm nitrogen.

[0084] Detergents: Metallic detergents that may be included in the electric motor drive train fluids described herein may generally include 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 generally described as normal or neutral salts, and generally have a total base number or TBN of 0 to less than 150 (as measured by ASTM D2896). Large amounts of metal bases 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 overalkaline detergent comprises micelles of a neutralizing detergent surrounding an inorganic metal base (e.g., a hydrated carbonate) core. Such overalkaline detergents may have a TBN of 150 or more, such as 150 to 450 or more.

[0085] Cleaning agents suitable for use in embodiments of the present invention include oil-soluble high-based, low-based and neutral sulfonates, phenates, sulfurized phenates and salicylates of metals, particularly alkali metals 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 detergents may be high-based calcium or magnesium sulfonates with a TBN of 150 to 450 TBN, high-based calcium or magnesium phenates or sulfurized phenates with a TBN of 150 to 300 TBN, and high-based calcium or magnesium salicylates with a TBN of 130 to 350. Mixtures of these salts may also be used.

[0086] The metal-containing detergent may 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 may be present in the fluid in an amount sufficient to provide up to 130 ppm of alkali metals and / or alkaline earth metals based on the total weight of the lubricating and cooling fluid.

[0087] In one approach, the preferred detergent may be a neutral to low base sulfonate, and in some approaches a calcium sulfonate. A suitable detergent may be a calcium sulfonate having a TBN of 50 or less, such as from about 25 to about 30.

[0088] Viscosity modifiers: The electric motor drive train fluid may optionally contain one or more viscosity modifiers. Suitable viscosity modifiers may include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutylenes, hydrogenated styrene-isoprene polymers, styrene / maleate copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkylstyrenes, hydrogenated alkenyl 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.

[0089] In addition to or in lieu of a viscosity modifier, the electric motor drive train fluids described herein may also optionally include 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.

[0090] 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.

[0091] 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 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 may be up to about 0.1 wt%, or up to about 0.05 wt%, or less than about 0.04 wt%, based on the total weight of the lubricating and cooling fluid.

[0092] Pour Point Depressants: The electric motor drive train 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. The pour point depressants (when present) may be present in an amount of about 0.001 wt % to about 0.04 wt %, based on the total weight of the lubricant.

[0093] In general, the lubricating and cooling fluids described herein may include additive components within the ranges listed in Table 2.

[0094] Table 2

[0095]

[0096] The percentages of the above components represent the weight percentages of the components by the total weight of the lubricating and cooling fluid containing the components. The additives used to prepare the compositions described herein can be blended into the base oil individually or in various sub-combinations. However, it may be appropriate to blend all components simultaneously using an additive concentrate (i.e., additives plus diluents, such as hydrocarbon solvents). 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.

[0097] Example

[0098] The present disclosure and its many advantages can be better understood by the following examples. The following examples are illustrative and do not limit their scope or spirit. Those skilled in the art will readily appreciate that variations of the parts, methods, steps and equipment described in these examples can be used. Unless otherwise indicated or apparent from the context of the discussion in the following examples and throughout the present disclosure, all percentages, ratios and parts mentioned in the present disclosure are by weight.

[0099] In order to demonstrate how the fluids herein achieve the wear, oxidation stability and conductivity tested, the fluids of the present invention herein are compared with fluids having various element relationships of nitrogen, boron, sulfur and / or phosphorus to evaluate wear, oxidation stability and conductivity. The FZG wear resistance, oxidation viscosity stability and conductivity of the formulations were evaluated. As shown in the following table, the inventive examples show improved wear performance, conductivity performance and oxidation stability compared to the comparative examples. The inventive examples with the required components and the required treatment rates are therefore suitable for lubricating the transmission system of electric or hybrid electric vehicles. The comparative examples that deliver too much phosphorus, too much friction modifier, too much detergent and / or contain too much dispersant derived from polyisobutylene with too low number average molecular weight have reduced wear performance, reduced oxidation stability and / or reduced conductivity, and are therefore not suitable for lubricating electric or hybrid electric vehicle transmission systems. All fluids tested herein are considered to be low viscosity fluids with kV100°C (ASTM D445) of about 3.2 to about 8 cSt.

[0100] The FZG abrasion resistance test is used to evaluate the abrasion resistance load capacity of a lubricant and is performed according to the A10 / 16.6R / 90 test of CEC L-84-02. The results are reported in failure load levels, and better results are obtained for samples with higher failure load levels. The lubricants of the present invention achieve a failure load level of at least 8.

[0101] Oxidative viscosity stability is used to evaluate the difference between the initial viscosity and the final viscosity after aging the fluid for 192 hours according to CEC L-48-A-00. Lower values ​​indicate improved performance. Thus, fluids with high oxidative stability exhibit only a small viscosity change before and after aging. The fluids herein have a viscosity change of about 0.5 cSt or less.

[0102] 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 (using Flucon Epsilon+ at 1.5V, 20Hz and 170°C to test lubricants rather than fuels). The fluids herein have a conductivity of about 130nS / m or less.

[0103] The inventive examples and comparative examples tested in Table 3 below all contained different amounts of sulfurized components, friction modifiers, and dispersants, as shown in Table 3. Otherwise, each fluid contained the same additional additives, including antioxidants, defoamers, corrosion inhibitors, detergents, demulsifiers, and process oils. The inventive examples and comparative examples were tested in Group IV base oils to obtain finished fluids having a 100°C kinematic viscosity as shown in the following table. The balanced delivery of sulfur, friction modifiers, and phosphorus from the dispersant in the inventive examples surprisingly improved wear, oxidation stability, and lubricant conductivity. Comparative examples that delivered too much phosphorus and / or included relatively low molecular weight dispersant additives and / or contained too much friction modifier had reduced wear or oxidation stability and / or lubricant conductivity. The details of these components used in these examples are described below:

[0104] · Sulfur component (S-1) : 2,5-dimercapto-1,3,4-thiadiazole and / or its derivatives containing about 35% by weight of sulfur, which is a 75:25 to 85:15 mixture of 2,5-bis-(nonyldithio)-1,3,4-thiadiazole and 2,5-mono-(nonyldithio)-1,3,4-thiadiazole.

[0105] · Dispersant 1 (Disp-1) : A phosphorylated and boronated 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 about 0.76% by weight phosphorus, about 0.35% by weight boron, and about 1.75% by weight nitrogen.

[0106] · Dispersant D-2 (Disp-2) : A phosphated and borated succinimide dispersant obtained 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% by weight nitrogen, about 0.15% by weight boron and about 0.35% by weight phosphorus.

[0107] · Detergent Additive 1 (Det-1) : Overbased calcium sulfonate having a TBN of about 300 and about 11.9 wt % calcium

[0108] · Friction Modifier 1(FM-1) :1-Hydroxyethyl-2-heptadecenyl imidazoline

[0109] · Friction Modifier 2(FM-2) : Branched C16 to C18 substituted succinic acid or anhydride reacted with ammonia

[0110] · Friction modifier 3(FM -3): Ethoxylated tallow alkylamine

[0111] Table 3: Fluid composition

[0112] Invention Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 S-1 (weight %) 0.31 0.31 0.31 0.35 0.35 Disp-1 (weight %) - - - - 3.8 Disp-2 (weight %) 7.4 7.4 7.4 8.3 - FM-1 (weight %) .02 .02 .02 .02 .02 FM-2 (weight %) 0.1 0.1 0.5 0.1 0.1 FM-3 (weight %) .14 base oil Group IV Group IV Group IV Group IV Group IV kV100℃,cSt* 6.2 6.2 6.1 6.4 6.2

[0113] *ASTM D445

[0114] Table 4: Fluid element analysis (calculated)

[0115]

[0116]

[0117] Table 5: Fluid properties

[0118]

[0119] **CEC L-84-02(A10 / 16.6R / 90)

[0120] ***CEC L-48-A

[0121] ****Perform ASTM D2624-15 (20Hz, 170°C) on Flucon epsilon or equivalent tester

[0122] Inventive Example 1 has acceptable FZG performance (8 or above), improved oxidation performance (the difference between initial viscosity and final viscosity after aging is 0.5 cSt or below), and improved conductivity (130 nS / m or below), while the comparative examples have reduced FZG performance, reduced oxidation performance, and / or reduced conductivity performance.

[0123] Inventive Example 2 and Comparative Example 5 are shown in Table 6 below. The examples were tested in Group III or Group IV / V base oils to obtain finished fluids having a kinematic viscosity at 100°C as shown in the following table. Inventive Example 2 and Comparative Example 5 contained different amounts of friction modifiers and detergents, as shown in Table 6 below. Otherwise, the examples contained similar amounts of additional additives, including antioxidants, defoamers, demulsifiers, and process oils. The balanced delivery of sulfur, friction modifiers, and dispersants in Inventive Example 2 surprisingly improved wear, oxidation stability, and lubricant conductivity. Comparative Example 5 contained too much friction modifier and too much detergent, so wear or oxidation stability and / or lubricant conductivity were reduced. Details of the additional components used in these examples are described below:

[0124] · Dispersant 3(D-3) : A succinimide dispersant obtained from a mixture of 950Mn polyisobutylene, maleic anhydride and a polyalkylene polyamine having an average of 6.5 nitrogen atoms per molecule. The dispersant has approximately 2.0 wt% nitrogen.

[0125] · Friction Modifier 4 (FM-4): Straight chain C16 to C18 substituted succinic acid or anhydride reacted with ammonia

[0126] · Friction Modifier 5 (FM-5) : A mixture of friction modifiers comprising: isodecyloxypropylamine, n-oleyl-1,3-diaminopropane and dimethyloctadecylamine

[0127] · Antioxidant (AO) : One or more antioxidants consisting of hindered phenols and alkylated diphenylamines

[0128] Table 6

[0129] Invention Example 2 Comparative Example 5 S-1 (weight %) 0.35 .35 Disp-2 (weight %) 4.5 6.0 Disp-3 (weight %) 0.4 0.5 FM-3 (weight %) 0.03 0.03 FM-4 (weight %) 0.30 0.40 FM-5 (weight %) - 0.09 AO 0.7 0.4 Balance base oil and VM Group III Group IV / V kV100℃,cSt* 3.5 4.1

[0130] *ASTM D445

[0131] Table 7: Fluid element analysis (calculated)

[0132] Invention Example 2 Comparative Example 5 Total phosphorus (delivered from dispersant), ppm 158 210 Nitrogen from dispersant, ppm 347 462 Boron from dispersant, ppm 68 90 Calcium from Det-1, ppm 119 214 Sulfur from S-1, ppm 1225 1225 P / S Ratio 0.13 0.17 P+S, ppm 1382 1435

[0133] Table 8: Fluid properties

[0134]

[0135] **CEC L-84-02(A10 / 16.6R / 90)

[0136] ***CEC L-48-A

[0137] ****Perform ASTM D2624-15 (20Hz, 170°C) on Flucon epsilon or equivalent tester

[0138] Inventive Example 2 has acceptable FZG performance (8 or above), improved oxidation performance (the difference between initial viscosity and final viscosity after aging is 0.5 cSt or less), and improved conductivity (130 nS / m or less), while Comparative Example 5 has reduced FZG performance, reduced oxidation performance and / or reduced conductivity performance.

[0139] It should be understood that while the lubricating compositions and compositions of the present disclosure have been described in conjunction with the detailed description thereof and the summary herein, the foregoing description is intended to illustrate and not to limit the scope of the present 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 illustrative only, with the true scope of the present disclosure being indicated by the appended claims.

[0140] 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, such as molecular weight, percentage, ratio, reaction conditions, etc., used in this specification are 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.At a minimum, and without attempting to limit the scope of the application of the principle 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.

[0141] 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 of the other components, compounds, substituents or parameters disclosed herein.

[0142] It should be further understood that each range disclosed herein should be interpreted as a disclosure of each specific value within the disclosed range with the same number of significant figures. Thus, a range of 1-4 would 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.

[0143] 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 in each range. Therefore, the present disclosure should be interpreted as the 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 in each range, or by combining each upper limit of each range with each specific value in each range.

[0144] In addition, a specific amount / value of a component, compound, substituent or parameter disclosed in this specification or the examples should be interpreted as a disclosure of a lower or upper limit of a range, and therefore can be combined with any other lower or upper limit or specific 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 powertrain fluid, the electric powertrain fluid comprising: one or more base oils of lubricating viscosity; a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 2000 or greater, wherein the succinimide dispersant has up 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 about 150 ppm to about 270 ppm of dispersant phosphorus (P) to the electric powertrain fluid; a sulfur-donating additive comprising a thiadiazole or a derivative thereof, wherein the thiadiazole or derivative thereof provides at least about 1000 ppm of thiadiazole sulfur (S) to the electric powertrain fluid; wherein the combined dispersant phosphorus and thiadiazole sulfur (P+S) is at least about 1300 ppm, and wherein the weight ratio of the dispersant phosphorus to the thiadiazole sulfur (P / S) is at least about 0.1; providing a detergent system that provides one or more calcium-containing detergents, and wherein the one or more calcium-containing detergents provide no more than about 200 ppm of calcium; No more than about 0.4 weight percent friction modifier; and wherein the electric powertrain fluid has a kV100 viscosity of about 3.2 cSt or greater, about 150 ppm to about 270 ppm total phosphorus, and a conductivity of about 130 nS / M or less as measured using the electric powertrain fluid by a modified conductivity test according to ASTM D2624-15 and measured at 20 Hz and 170°C.

2. The electric powertrain fluid of claim 1, wherein the friction modifier is an alkylimide, an alkylamine, a hydrocarbyl imidazole, a derivative thereof, or a combination thereof; and / or wherein the friction modifier is 0 wt % to about 0.08 wt % of an ethoxylated alkylamine; and / or wherein the organic friction modifier is 0 wt % to about 0.4 wt % of a linear or branched C16 to C18 substituted succinic acid or anhydride reacted with an amine, polyamine, or ammonia.

3. The electric powertrain fluid of claim 1, wherein the number average molecular weight of the polyisobutylene is from about 2,000 to about 2,400; and / or wherein the electric motor lubrication fluid comprises from about 2 wt % to about 8 wt % of the succinimide dispersant. 4 . The electric power train fluid of claim 1 , wherein the electric power train fluid has a viscosity change of less than 0.5 cSt after the electric power train fluid has been aged in accordance with CECL-48-A.

5. The electric power train fluid of claim 1, wherein the electric power train fluid achieves a failure load rating of at least about 8 in the FZG A10 / 16.6R / 120 Scuff Resistance Test of CEC L-84-02.

6. The electric power train fluid of claim 1, wherein the thiadiazole or derivative thereof provides about 1500 ppm or less sulfur.

7. The electric powertrain fluid of claim 1, wherein the combined dispersant phosphorus and thiadiazole sulfur (P+S) is about 1300 ppm to about 1400 ppm; and / or wherein the weight ratio of the dispersant phosphorus to the thiadiazole sulfur (P / S) is about 0.1 to about 0.

3.

8. The electric powertrain fluid of claim 1 , wherein about 90% to about 100% of the total phosphorus is provided by the succinimide dispersant; and / or wherein the amount of phosphorus provided is about 1 ppm phosphorus per 8 to 13 number average molecular weight units of the polyisobutylene portion of the succinimide dispersant.

9. The electric powertrain fluid of claim 1, wherein the thiadiazole or derivative thereof comprises one or more compounds having a structure of Formula I: 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 part of the integer n is 0, and if R 10 is sulfur, then the adjacent R 11 Part of said n is 1; and At least one of the R 10 It's sulfur.

10. A method for lubricating a drive train component including an electric motor, the method comprising: lubricating the powertrain components with an electric powertrain fluid; The electric powertrain fluid comprises: (i) one or more base oils of lubricating viscosity; (ii) a succinimide dispersant derived from polyisobutylene having a number average molecular weight of about 2000 or greater, wherein the succinimide dispersant has up to about 1 weight percent nitrogen and is post-treated with a phosphorus-containing compound and a boron-containing compound, and wherein the succinimide dispersant delivers about 150 ppm to about 270 ppm of dispersant phosphorus (P) to the electric powertrain fluid; (iii) a sulfur-donating additive comprising a thiadiazole or a derivative thereof, the thiadiazole or derivative thereof providing at least about 1000 ppm of thiadiazole sulfur (S) to the electric powertrain fluid, wherein the combined dispersant phosphorus and thiadiazole sulfur (P+S) is at least about 1300 ppm, and wherein the weight ratio of the dispersant phosphorus to the thiadiazole sulfur (P / S) is at least about 0.1; (iv) providing a detergent system comprising one or more calcium-containing detergents, wherein the one or more calcium-containing detergents provide no more than about 200 ppm of calcium; and (v) no more than about 0.4 wt. % of a friction modifier; and wherein the electric powertrain fluid has a kV100 viscosity of about 3.2 cSt or greater, about 150 ppm to about 270 ppm total phosphorus, and a conductivity of about 130 nS / M or less as measured using the electric powertrain fluid by a modified conductivity test according to ASTM D2624-15 and measured at 20 Hz and 170°C.

11. The method for lubricating a powertrain component including an electric motor according to claim 10, wherein the friction modifier is an alkylimide, an alkylamine, a hydrocarbyl imidazole, a derivative thereof, or a combination thereof; and / or wherein the friction modifier is 0 wt % to about 0.08 wt % of an ethoxylated alkylamine; and / or wherein the friction modifier is 0 wt % to about 0.4 wt % of a linear or branched C16 to C18 substituted succinic acid or anhydride reacted with an amine, polyamine, or ammonia.

12. The method for lubricating a powertrain component including an electric motor according to claim 10, wherein the number average molecular weight of the polyisobutylene is from about 2,000 to about 2,400; and / or wherein the electric powertrain fluid comprises from about 2 wt % to about 8 wt % of the succinimide dispersant.

13. The method for lubricating a powertrain component including an electric motor according to claim 10, wherein the powertrain fluid has a post-aging viscosity change of less than about 0.5 cSt after the powertrain fluid has been aged in accordance with CEC L-48-A.

14. The method for lubricating a powertrain component including an electric motor according to claim 10, wherein the electric powertrain fluid achieves a failure load rating of at least about 8 in the FZG A10 / 16.6R / 120 Scuff Resistance Test of CEC L-84-02.

15. The method for lubricating a drive train component including an electric motor according to claim 10, wherein about 90% to about 100% of the total phosphorus is provided by the succinimide dispersant; and / or wherein the thiadiazole or derivative thereof comprises one or more compounds having a 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 part of the integer n is 0, and if R 10 is sulfur, then the adjacent R 11 Part of said n is 1; and At least one of the R 10 It's sulfur.

Images