Lubricating oil composition for automatic transmissions

Abstract

The present invention relates generally to lubricating oil compositions useful in automatic transmissions, and particularly in transmission oils for automotive automatic transmissions in battery electric vehicles (BEVs), hybrid electric vehicles (HVs), and plug-in hybrid electric vehicles (PHVs). The lubricants are free of metal compounds (e.g., Ca, Mo, or Zn) and demonstrate high volume resistivity, wear protection, and copper corrosion resistance.

Description

[Technical Field]

[0001] The present invention relates generally to lubricating oil compositions useful in automatic transmissions, particularly in electric vehicle (EV) automatic transmissions. [Background technology]

[0002] Automatic transmission lubricants, also known as automatic transmission fluids, are traditionally used to aid in the smooth operation of automatic transmissions, which are found in automobiles and include a torque converter, gear train, wet clutch, and hydraulic system.

[0003] Battery electric vehicles (BEVs), hybrid electric vehicles (HVs), and plug-in hybrid electric vehicles (PHVs), which have electric motors and / or generators built into the transmission, present unique challenges for the lubrication industry. Copper is present in many of the electrical systems in the powertrains of electric and HVs and can corrode at high temperatures. Lubricants in electric and HVs must therefore provide adequate copper corrosion protection to minimize corrosion.

[0004] Volume resistivity (the fluid's resistance to electrical current) can also be an issue. If resistivity is too low, the powertrain will leak charge and become less efficient. The presence of metal ions reduces the fluid's volume resistivity. Metals commonly used in lubricants for conventional internal combustion engines, such as Ca, Mo, and Zn, therefore must be minimized in electric vehicles to meet volume resistivity requirements.

[0005] Yet another challenge in BEVs, HVs, and PHVs is wear protection. Unlike conventional vehicles powered by internal combustion engines, in electric vehicles the same lubricating fluid is shared by the electric motor and transmission. The planetary gears used in the transmission systems of BEVs, HVs, and PHVs can present challenges with wear protection. While phosphorus-based and sulfur-based extreme pressure additives can provide wear protection, sulfur compounds can oxidize to acidic species at high temperatures and contribute to increased corrosion.

[0006] Given the complexities associated with lubricating BEVs, HVs, and PHVs, there is a need for lubricants that balance wear protection with good copper corrosion resistance and sufficient volume resistivity.

[0007] The disclosed technology relates to lubricants suitable for use in electric, hybrid, and plug-in hybrid vehicles with electric motors and / or generators built into the transmission. The lubricants are substantially free of metal compounds (e.g., Ca, Mo, or Zn) and demonstrate high volume resistivity, wear protection, and copper corrosion resistance. Summary of the Invention

[0008] According to one embodiment of the present invention, there is provided a lubricating oil composition for battery electric vehicles (BEVs), hybrid vehicles (HVs) and plug-in hybrid vehicles (PHVs) equipped with electric motors and / or generators, comprising: a. Approximately 1.5 to 20 mm at 100°C 2 a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of / s; b. a phosphorus antiwear additive selected from inorganic phosphoric acids, acid or neutral phosphite esters, acid or neutral phosphate esters and their amine salts, or combinations thereof; c. a nitrogen-based corrosion inhibitor, wherein the total amount of nitrogen provided by the corrosion inhibitor to the lubricating oil composition is 125 ppm or less, based on the weight of the lubricating oil composition; d. a sulfur EP additive, wherein the total amount of sulfur provided by the sulfur EP additive to the lubricating oil composition is 300 to 1500 ppm by weight of the lubricating oil composition; and the lubricating oil composition contains less than 50 ppm metals and has a 1.0 x 10 9 Lubricating oil compositions are provided that have a volume resistivity greater than Ω·cm.

[0009] According to another embodiment of the present invention, there is provided a method for reducing corrosion and improving wear protection in a transmission system of a battery electric vehicle (BEV), hybrid vehicle (HV), and plug-in hybrid vehicle (PHV) having an electric motor and / or generator, comprising: a. Approximately 1.5 to 20 mm at 100°C 2 a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of / s; b. a phosphorus antiwear additive selected from inorganic phosphoric acids, acid or neutral phosphite esters, acid or neutral phosphate esters and their amine salts, or combinations thereof; c. a nitrogen-based corrosion inhibitor, wherein the total amount of nitrogen provided by the corrosion inhibitor to the lubricating oil composition is 125 ppm or less, based on the weight of the lubricating oil composition; d. a sulfur EP additive, wherein the total amount of sulfur provided by the sulfur EP additive to the lubricating oil composition is 300 to 1500 ppm by weight of the lubricating oil composition; and lubricating and operating the transmission system with a lubricating oil composition comprising: 9 A method is provided in which the material has a volume resistivity of greater than Ω·cm.

[0010] According to another embodiment of the present invention, there is provided a use of a lubricating oil composition for reducing corrosion and improving wear protection in the transmission systems of battery electric vehicles (BEVs), hybrid electric vehicles (HVs) and plug-in hybrid electric vehicles (PHVs) having electric motors and / or generators, comprising: a. Approximately 1.5 to 20 mm at 100°C 2 a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of / s; b. a phosphorus antiwear additive selected from inorganic phosphoric acids, acid or neutral phosphite esters, acid or neutral phosphate esters and their amine salts, or combinations thereof; c. a nitrogen-based corrosion inhibitor, wherein the total amount of nitrogen provided by the corrosion inhibitor to the lubricating oil composition is 125 ppm or less, based on the weight of the lubricating oil composition; d. a sulfur EP additive, wherein the total amount of sulfur provided by the sulfur EP additive to the lubricating oil composition is 300 to 1500 ppm by weight of the lubricating oil composition; and lubricating and operating the transmission system with a lubricating oil composition comprising: 9 Use is provided, which has a volume resistivity of greater than Ω·cm. DETAILED DESCRIPTION OF THE INVENTION

[0011] Definition: The following terms are used throughout this specification and have the following meanings unless otherwise indicated.

[0012] The term "major amount" of base oil refers to an amount of base oil that is at least 40 wt% of the lubricating oil composition. In some embodiments, a "major amount" of base oil refers to an amount of base oil that is greater than 50 wt%, greater than 60 wt%, greater than 70 wt%, greater than 80 wt%, or greater than 90 wt% of the lubricating oil composition.

[0013] The term "substantially free" of metals refers to levels of metals present in the lubricating oil composition at or below 50 ppm.

[0014] In the following description, all numerical values ​​disclosed herein, regardless of whether the term "about" or "approximately" is used in conjunction therewith, are approximate values ​​that may vary by 1 percent, 2 percent, 5 percent, or sometimes 10-20 percent.

[0015] The term "total base number" or "TBN" refers to the level of alkalinity in an oil sample, indicating the ability of a composition to continue to neutralize corrosive acids, according to ASTM Standard No. D2896 or an equivalent procedure. The test measures the change in electrical conductivity, and the results are expressed as mgKOH / g (the equivalent number of milligrams of KOH required to neutralize one gram of product). Thus, a high TBN reflects a strongly overbased product and, consequently, a higher base reserve for neutralizing acids.

[0016] The term "PIB" refers to poly-isobutylene.

[0017] lubricating viscosity oil The lubricating oil compositions disclosed herein typically contain at least one oil of lubricating viscosity. Any base oil known to those skilled in the art can be used as the oil of lubricating viscosity disclosed herein. Some base oils suitable for preparing the lubricating oil compositions are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London, Springer, Chapters 1 and 2 (1996); and A. Sequeria, Jr., "Lubricant Base Oil and Wax Processing," New York, Marcel Decker, Chapter 6, (1994); and DV Brock, Lubrication Engineering, Vol. 43, pages 184-5, (1987) (all of which are incorporated herein by reference). Typically, the amount of base oil in the lubricating oil composition can be about 70 to about 99.5 wt %, based on the total weight of the lubricating oil composition. In some embodiments, the amount of base oil in the lubricating oil composition can be from about 75 to about 99 wt %, from about 80 to about 98.5 wt %, or from about 80 to about 98 wt %, based on the total weight of the lubricating oil composition.

[0018] In certain embodiments, the base oil is or includes any natural or synthetic lubricating base oil fraction. Some non-limiting examples of synthetic oils include oils such as polyalphaolefins (PAOs) prepared from the polymerization of at least one alpha-olefin, such as ethylene, or from hydrocarbon synthesis procedures using carbon monoxide and hydrogen gas, such as the Fischer-Tropsch process. In certain embodiments, the base oil includes less than about 10 wt.% of one or more heavy fractions, based on the total weight of the base oil. Heavy fractions refer to lubricating oil fractions having a viscosity of at least about 20 cSt at 100°C. In certain embodiments, heavy fractions have a viscosity of at least about 25 cSt or at least about 30 cSt at 100°C. In further embodiments, the amount of one or more heavy fractions in the base oil is less than about 10 wt.%, less than about 5 wt.%, less than about 2.5 wt.%, less than about 1 wt.%, or less than about 0.1 wt.%, based on the total weight of the base oil. In still further embodiments, the base oil does not include any heavy fractions.

[0019] In certain embodiments, the lubricating oil composition comprises a major amount of a base oil of lubricating viscosity. In some embodiments, the base oil has a kinematic viscosity at 100° C. of from about 1.5 centistokes (cSt) to about 20 cSt, from about 2 centistokes (cSt) to about 20 cSt, or from about 2 cSt to about 16 cSt. The kinematic viscosity of the base oils or lubricating oil compositions disclosed herein may be measured according to ASTM D 445, which is incorporated herein by reference.

[0020] In other embodiments, the base oil is or comprises a base stock or a blend of base stocks. In further embodiments, the base stocks are produced using a variety of different processes, including, but not limited to, extraction, solvent refining, hydrotreating, oligomerization, esterification, and rerefining. In some embodiments, the base stock comprises a rerefined stock. In further embodiments, the rerefined stock is substantially free of materials introduced through manufacturing, contamination, or prior use.

[0021] In some embodiments, the base oil comprises one or more base stocks in one or more of Groups I through V as defined in American Petroleum Institute (API) Publication 1509, Fourteen Edition, December 1996 (i.e., API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils), incorporated herein by reference. The API guidelines define base stocks as lubricating components that can be produced using a variety of different processes. Group I, II, and III base stocks are mineral oils, each with a specific range of saturates, sulfur content, and viscosity index. Group IV base stocks are polyalphaolefins (PAOs). Group V base stocks include all other base stocks not included in Group I, II, III, or IV.

[0022] In some embodiments, the base oil comprises one or more base stocks in Group I, II, III, IV, V, or a combination thereof. In other embodiments, the base oil comprises one or more base stocks in Group II, III, IV, or a combination thereof. In further embodiments, the base oil comprises one or more base stocks in Group II, III, IV, or a combination thereof, and the base oil has a kinematic viscosity at 100°C of from about 1.5 centistokes (cSt) to about 20 cSt, from about 2 cSt to about 20 cSt, or from about 2 cSt to about 16 cSt. In some embodiments, the base oil is a Group II base oil.

[0023] The base oil may be selected from the group consisting of natural oils of lubricating viscosity, synthetic oils of lubricating viscosity, and mixtures thereof. In some embodiments, base oils include base stocks obtained by isomerization of synthetic wax and slack wax, and hydrocracked base stocks produced by hydrocracking (rather than solvent extraction) the aromatic and polar components of the crude. In other embodiments, the base oil of lubricating viscosity includes natural oils, such as animal oils, vegetable oils, mineral oils (e.g., liquid petroleum oils and solvent-treated or acid-treated mineral oils of the paraffinic, naphthenic, or mixed paraffinic-naphthenic type), oils derived from coal or shale, and combinations thereof. Some non-limiting examples of animal oils include bone oil, lanolin, fish oil, lard oil, dolphin oil, seal oil, shark oil, tallow oil, and whale oil. Some non-limiting examples of vegetable oils include castor oil, olive oil, peanut oil, rapeseed oil, corn oil, sesame oil, cottonseed oil, soybean oil, sunflower oil, safflower oil, hemp oil, linseed oil, tung oil, oiticica oil, jojoba oil, and meadowfoam oil. Such oils may be partially or fully hydrogenated.

[0024] In some embodiments, synthetic oils of lubricating viscosity include hydrocarbon oils and halo-substituted hydrocarbon oils, such as polymerized and interpolymerized olefins, alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl sulfides, and derivatives thereof, analogs thereof, and homologs thereof. In other embodiments, synthetic oils include alkylene oxide polymers, interpolymers, copolymers, and derivatives thereof, in which the terminal hydroxyl groups may be modified by esterification, etherification, etc. In further embodiments, synthetic oils include esters of dicarboxylic acids with various alcohols. In certain embodiments, synthetic oils include C5-C6 alkylene oxide polymers, interpolymers, copolymers, and derivatives thereof. 12 Included are esters made from monocarboxylic acids and polyols and polyol ethers. In a further embodiment, the synthetic oils include tri-alkyl phosphate ester oils, such as tri-n-butyl phosphate and tri-iso-butyl phosphate.

[0025] In some embodiments, synthetic oils of lubricating viscosity include silicon-based oils (such as polyacrylic-, polyaryl-, polyalkoxy-, polyaryloxy-siloxane oils and silicate oils), hi other embodiments, synthetic oils include liquid esters of phosphorus-containing acids, polymeric tetrahydrofurans, polyalphaolefins, and the like.

[0026] Base oils derived from the hydroisomerization of wax may also be used, either alone or in combination with the aforementioned natural and / or synthetic base oils. Such wax isomerate oils are produced by the hydroisomerization of natural or synthetic waxes or mixtures thereof over a hydroisomerization catalyst.

[0027] In a further embodiment, the base oil comprises a poly-alpha-olefin (PAO). Typically, the poly-alpha-olefin may be derived from an alpha-olefin having from about 1.5 to about 30, from about 2 to about 20, or from about 2 to about 16 carbon atoms. Non-limiting examples of suitable poly-alpha-olefins include those derived from octene, decene, mixtures thereof, and the like. These poly-alpha-olefins may have a viscosity of from about 1.5 to about 15, from about 1.5 to about 12, or from about 1.5 to about 8 centistokes at 100°C. In some examples, the poly-alpha-olefin may be used with other base oils, such as mineral oil.

[0028] In further embodiments, the base oil comprises a polyalkylene glycol or polyalkylene glycol derivative, wherein the terminal hydroxyl groups of the polyalkylene glycol may be modified by esterification, etherification, acetylation, etc. Non-limiting examples of suitable polyalkylene glycols include polyethylene glycol, polypropylene glycol, polyisopropylene glycol, and combinations thereof. Non-limiting examples of suitable polyalkylene glycol derivatives include ethers of polyalkylene glycols (e.g., methyl ether of polyisopropylene glycol, diphenyl ether of polyethylene glycol, diethyl ether of polypropylene glycol, etc.), mono- and polycarboxylic acid esters of polyalkylene glycols, and combinations thereof. In some examples, the polyalkylene glycol or polyalkylene glycol derivative may be used together with other base oils, such as poly-alpha-olefins and mineral oils.

[0029] In further embodiments, the base oil comprises any of the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc.) with various alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc.). Non-limiting examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, 2-ethylhexyl diester of linoleic acid dimer, etc.

[0030] In a further embodiment, the base oil comprises hydrocarbons prepared by the Fischer-Tropsch process, which uses a Fischer-Tropsch catalyst to prepare hydrocarbons from gases containing hydrogen and carbon monoxide. These hydrocarbons may require further processing to be useful as base oils. For example, the hydrocarbons may be dewaxed, hydroisomerized, and / or hydrocracked using processes known to those skilled in the art.

[0031] In a further embodiment, the base oil comprises an unrefined oil, a refined oil, a re-refined oil, or a mixture thereof. Unrefined oils are those obtained directly from natural or synthetic sources without further purification treatment. Non-limiting examples of unrefined oils include shale oil obtained directly from a retorting procedure, petroleum oil obtained directly from primary distillation, and ester oil obtained directly from an esterification process and used without further treatment. Refined oils are similar to unrefined oils, except that the former have been further processed by one or more purification processes to improve one or more properties. Many such purification processes, such as solvent extraction, secondary extraction, acid or base extraction, filtration, and percolation, are known to those skilled in the art. Re-refined oils are obtained by applying processes similar to those used to obtain refined oils to refined oils. Such re-refined oils are also known as reclaimed or reprocessed oils and often may be additionally processed by processes involving the removal of spent additives and oil breakdown products.

[0032] Phosphorus Additive In one embodiment, one or more phosphorus-containing anti-wear additives are present in the lubricating oil composition.

[0033] In some embodiments, the one or more phosphorus-containing anti-wear additives are present in the lubricating oil composition from 100 to 1000, 200 to 500, 250 to 450, 275 to 425, 275 to 415, 290 to 400 ppm by weight based on the weight of the lubricating oil composition.

[0034] The phosphorus additive may be a phosphite ester, a phosphate ester, a phosphate amine, a phosphoric acid, or a combination thereof.

[0035] (a) Phosphite ester Phosphite esters include mono-, di-, and trihydrocarbyl phosphites, with dihydrocarbyl hydrogen phosphites or trihydrocarbyl phosphites being preferred.

[0036] In one embodiment, the phosphorus-containing anti-wear additive is a dihydrocarbyl hydrogen phosphite. The dihydrocarbyl hydrogen phosphite has the following formula (1): O=P(OR)2H Formula (I) (wherein R represents a hydrocarbon group having 1 to 30 carbon atoms).

[0037] Specific examples of dihydrocarbyl hydrogen phosphites include aryl dihydrocarbyl hydrogen phosphites, such as diphenyl hydrogen phosphite, dicresyl hydrogen phosphite, phenylcresyl hydrogen phosphite, monophenyl 2-ethylhexyl hydrogen phosphite; and aliphatic dihydrocarbyl phosphites, such as dibutyl hydrogen phosphite, dioctyl hydrogen phosphite, diisooctyl hydrogen phosphite, di(2-ethylhexyl) hydrogen phosphite, didecyl hydrogen phosphite, diolyl hydrogen phosphite, dilauryl hydrogen phosphite, and distearyl hydrogen phosphite.

[0038] In one embodiment, the phosphorus-containing anti-wear additive is a trihydrocarbyl phosphite. The trihydrocarbyl phosphite has the following formula (II): P(OR)3 formula (II), (wherein R represents a hydrocarbon group having 1 to 30 carbon atoms).

[0039] Specific examples of trihydrocarbyl phosphites include aryl trihydrocarbyl phosphites, such as triphenyl phosphite, tricresyl phosphite, trisnonylphenyl phosphite, diphenyl mono-2-ethylhexyl phosphite, and diphenyl monotridecyl phosphite; and aliphatic trihydrocarbyl phosphites, such as tributyl phosphite, trioctyl phosphite, triisooctyl phosphite, tri(2-ethylhexyl) phosphite, trisdecyl phosphite, trioleyl phosphite, trilauryl phosphite, and tristearyl phosphite.

[0040] In one embodiment, the phosphite ester is present at 0.01 to 1.0, 0.05 to 0.8, 0.06 to 0.5, 0.07 to 0.3, 0.07 to 0.2, 0.08 to 0.2, 0.09 to 0.18, 0.09 to 0.16, 0.08 to 0.14, 0.08 to 0.13, 0.09 to 0.12, 0.09 to 0.11, 0.10 wt %, based on the weight of the lubricating oil composition.

[0041] In one embodiment, the phosphite ester has a phosphorus content of 5 to 20, 7 to 18, 9 to 16, 10 to 15, 11 to 14, 12 to 14, 13.3 weight percent based on the weight of the phosphite ester.

[0042] (b) Phosphate amine Specifically, examples of phosphate ester amine salts include those represented by the following formula III: (OR)x(OH)yP=O [Formula III] wherein x+y=3 and R represents an alkyl group having 1 to 30 carbons.

[0043] Specific examples of alkyl groups represented by R include linear or branched alkyl groups having 1 to 18, preferably 1 to 12, carbon atoms, examples of which include methyl, ethyl, n-propyl, isopropyl, various butyl groups, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various undecyl groups, various dodecyl groups, various tridecyl groups, various tetradecyl groups, various pentadecyl groups, various hexadecyl groups, various heptadecyl groups, and various octadecyl groups.

[0044] The amine can be a primary amine, a secondary amine, a tertiary amine, or a tertiary alkyl primary amine. Examples of the aforementioned amines also include those having the general formula: [ka] (wherein R1, R2, and R3 are an aliphatic hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom, and at least one of R1, R2, and R3 is an aliphatic hydrocarbon group having 1 to 20 carbon atoms). Here, the aliphatic hydrocarbon group is preferably an alkyl group or an unsaturated hydrocarbon group having 1 to 2 unsaturated double bonds, and the alkyl group and the unsaturated hydrocarbon group may each be linear, branched, or cyclic. The aliphatic hydrocarbon group preferably has 6 to 20 carbon atoms, and more preferably has 12 to 20 carbon atoms. The amine is even more preferably a primary amine in which the aliphatic hydrocarbon group has 12 to 20 carbon atoms.

[0045] In one embodiment, the alkyl phosphate amine salt is present in 0.05-1.0 wt % of the lubricating oil composition, hi other embodiments, the alkyl phosphate amine salt is present in the lubricating oil composition at 0.01-0.5 wt %, 0.05-0.25 wt %, 0.06-0.25 wt %, 0.07-0.20 wt %, 0.08-0.19 wt %, 0.08-0.18 wt %, 0.09-0.17 wt %, 0.09-0.16 wt %, or 0.1-0.15 wt %.

[0046] In one embodiment, the phosphate amine has a phosphorus content of 2.0 to 12.0 wt %. In other embodiments, the phosphorus additive has a phosphorus content of 5.0 to 11.0 wt %, 6.0 to 10.0 wt %, 7.0 to 10.0 wt %, 7.5 to 9.5 wt %, 7.8 to 9.0 wt %, or 8.0 to 8.5 wt %.

[0047] In one embodiment, the phosphate amine salt has a total nitrogen content of 0.10 to 5.0 wt %, 0.50 to 4.0 wt %, 0.70 to 3.0 wt %, 0.9 to 2.5 wt %, 1.0 to 2.3 wt %, 1.2 to 2.2 wt %, 0.15 to 2.0 wt %, or 1.6 to 1.9 wt %.

[0048] (c) Phosphoric acid The phosphoric acid is an inorganic phosphoric acid of formula (IV) H3PO4. The inorganic phosphoric acid is present in the lubricating oil composition at 0.01 to 0.09 wt%, 0.02 to 0.08 wt%, 0.02 to 0.07 wt%, 0.02 to 0.06 wt%, 0.025 to 0.055 wt%, or 0.03 to 0.05 wt%.

[0049] Sulfur-based extreme pressure (EP) additives The lubricating oil compositions disclosed herein contain extreme pressure (EP) agents that can prevent seizure of sliding metal surfaces under extreme pressure conditions. Any extreme pressure agent known to those skilled in the art can be used in the lubricating oil compositions. Typically, extreme pressure agents are compounds that can chemically combine with metals to form a surface film that prevents welding of asperities on opposing metal surfaces under high loads. Examples of sulfur-based extreme pressure agents include sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefin dihydrocarbyl polysulfides, thiadiazole compounds, thiophosphate esters (thiophosphites and thiophosphates), alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, and dialkylthiodipropionate compounds.

[0050] In one embodiment, the sulfur-based extreme pressure additive is a thiadiazole compound. Thiadiazole compounds, in particular, provide good resistance to wear of metal-to-metal surfaces. Preferably, thiadiazole compounds, such as 1,3,4-thiadiazole, 1,2,4-thiadiazole, and 1,4,5-thiadiazole, are preferred.

[0051] In one embodiment, the thiadiazole compound is a 1,3,4-thiadiazole, particularly 2,5-bis(hydrocarbyldithio)-1,3,4-thiadiazole (exemplified by Formula V below): [ka]

[0052] In the above structure, R1 and R2 each represent an alkyl group having 1 to 30 carbon atoms, preferably 6 to 18 carbon atoms. The alkyl group can be linear or branched. R1 and R2 can be the same or different from each other.

[0053] Specific examples of alkyl groups represented by R and R in the above general structure include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, the various pentyl groups, the various hexyl groups, the various heptyl groups, the various octyl groups, the various nonyl groups, the various decyl groups, the various undecyl groups, the various dodecyl groups, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups.

[0054] In one embodiment, the amount of sulfur-based extreme pressure additive can be from about 0.01 wt % to about 3 wt %, from about 0.05 wt % to about 1.5 wt %, from 0.05 wt % to about 1.5 wt %, from 0.05 wt % to about 1.0 wt %, from 0.05 wt % to about 0.75 wt %, from 0.05 wt % to about 0.5 wt %, or from about 0.08 wt % to about 1.0 wt %, from 0.08 wt % to about 0.7 wt %, from 0.08 wt % to about 0.6 wt %, from 0.08 wt % to about 0.5 wt %, or from 0.09 wt % to about 0.8 wt %, based on the total weight of the lubricating oil composition.

[0055] In one embodiment, the amount of sulfur from the sulfur-based extreme pressure additive is from 300 to 1500, 300 to 1400, 300 to 1300, 300 to 1200, 300 to 1100, 300 to 1050 ppm by weight, based on the total weight of the lubricating oil composition.

[0056] corrosion inhibitors The lubricating oil composition disclosed herein includes a corrosion inhibitor capable of reducing corrosion. The corrosion inhibitor can be a nitrogen-containing heterocyclic compound and its derivative. In an embodiment, the triazole of the present disclosure is one that does not contain any active sulfur group. Alkyl and aryl derivatives of triazole are preferred. Tolyltriazole is most preferred. These can be substituted or unsubstituted. The tolyltriazole compound of the present invention is exemplified by the following formula VI: [ka]

[0057] In the above formula, R3 represents hydrogen or an alkyl group having 1 to 30 carbon atoms. R3 can be linear or branched, and it can be saturated or unsaturated. It can contain a ring structure that is alkyl or aromatic in nature. R3 can also contain heteroatoms such as N, O, or S.

[0058] The substituted triazoles of the present invention can be prepared by condensing a basic triazole with an aldehyde and an amine via its acidic -NH group. In some embodiments, the substituted triazole is a reaction product of a triazole, an aldehyde, and an amine. Suitable triazoles that can be used to prepare the substituted triazoles of the present disclosure include triazole, alkyl-substituted triazoles, benzotriazole, tolyltriazole, or other aryltriazoles, while suitable aldehydes include reactive equivalents such as formaldehyde and formalin, and suitable amines include primary or secondary amines. In some embodiments, the amine is a secondary amine and is also a branched amine. In yet further embodiments, the amine is a beta-branched amine, such as bis-2-ethylhexylamine.

[0059] In one embodiment, the substituted triazole of the present invention is an alkyl-substituted triazole. In another embodiment, the substituted triazole of the present invention is a benzotriazole. The lubricating oil compositions of this disclosure typically contain from about 0.01 to about 1.0 weight percent triazole, but may also contain from about 0.02 to 0.08, 0.02 to 0.07, 0.02 to 0.06, 0.02 to about 0.05, or 0.03 to about 0.05 weight percent triazole compound.

[0060] In one embodiment, the corrosion inhibitor is present at 125 ppm or less by weight based on the weight of the lubricating oil composition, hi other embodiments, the corrosion inhibitor is present at 20-125, 25-110, 30-105, 35-100, 40-100, or 43-95 ppm by weight based on the weight of the lubricating oil composition.

[0061] Other additives Optionally, the lubricating oil composition may further comprise at least one additive or modifier (hereinafter referred to as "additive") that can impart or improve any desired property of the lubricating oil composition. Any additive known to a person skilled in the art may be used in the lubricating oil compositions disclosed herein. Some suitable additives are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London, Springer, (1996); and Leslie R. Rudnick, "Lubricant Additives: Chemistry and Applications," New York, Marcel Dekker (2003), both of which are incorporated herein by reference. In some embodiments, the additives may be selected from the group consisting of antioxidants, antiwear agents, rust inhibitors, demulsifiers, friction modifiers, multifunctional additives, viscosity index improvers, pour point depressants, foam inhibitors, metal deactivators, dispersants, corrosion inhibitors, lubricity improvers, thermal stability improvers, anti-haze additives, icing inhibitors, pigments, markers, static dissipative agents, biocides, and combinations thereof. Typically, the concentration of each of the additives in the lubricating oil composition, if used, may range from about 0.001 wt. % to about 15 wt. %, from about 0.01 wt. % to about 10 wt. %, or from about 0.1 wt. % to about 8 wt. %, based on the total weight of the lubricating oil composition. Furthermore, the total amount of additives in the lubricating oil composition may range from about 0.001 wt. % to about 20 wt. %, from about 0.01 wt. % to about 10 wt. %, or from about 0.1 wt. % to about 8 wt. %, based on the total weight of the lubricating oil composition.

[0062] The lubricating oil compositions disclosed herein are substantially free of metals (i.e., contain less than 50 ppm of metals). Newcomb, T., et al., "Electrical Conductivity of New and Used Automatic Transmission Fluids," SAE Int. J. Fuel Lubr. 9(3):2016, doi:10.4271 / 2016-01-2205, showed that the presence of polar or ionic compounds increases the conductivity of transmission fluids (thereby decreasing their volume resistivity). Metal-containing additives, such as detergents, in particular, negatively affect the volume resistivity of lubricating oil compositions and should therefore be minimized, while the presence of dispersants, friction modifiers, and wear inhibitors also contribute to increasing bulk fluid conductivity.

[0063] The optional additives described above are ashless (metal-free) and also have a volume resistivity of less than 1.0 x 10 9 A sufficiently high volume resistivity is selected to be greater than Ω·cm. A sufficiently high volume resistivity is necessary to provide adequate insulating properties in the lubricating oil composition.

[0064] The lubricating oil composition of the present invention may contain one or more ashless dispersants. Typically, ashless dispersants are nitrogen-containing dispersants formed by reacting alkenyl succinic anhydride with an amine. Examples of such dispersants are alkenyl succinimides and succinamides. These dispersants can be further modified, for example, by reaction with boron or ethylene carbonate. Ester-based ashless dispersants derived from long-chain hydrocarbon-substituted carboxylic acids and hydroxy compounds can also be used. Preferred ashless dispersants are those derived from polyisobutenyl succinic anhydride. These dispersants are commercially available.

[0065] Optionally, the lubricating oil compositions disclosed herein may further comprise a friction modifier. A variety of known friction modifiers may be used as the friction modifier contained in the lubricating oil compositions of the present invention, but low molecular weight C6-C 30Hydrocarbon-substituted succinimides or polyols are preferred. The friction modifiers can be used alone or in combination. In some embodiments, the friction modifiers are present in the lubricating oil composition in an amount of 0.01 to 5 wt. %. In other embodiments, the friction modifiers are present in the lubricating oil composition in an amount of 0.01 to 3.0, 0.01 to 2.0 wt. %, 0.01 to 1.5, 0.01 to 1.0, or 0.01 to 1.0.

[0066] Optionally, the lubricating oil compositions disclosed herein may further comprise an antioxidant capable of reducing or preventing oxidation of the base oil. Any antioxidant known to those skilled in the art may be used in the lubricating oil compositions. Non-limiting examples of suitable antioxidants include amine-based antioxidants (e.g., alkyldiphenylamines, phenyl-α-naphthylamines, alkyl- or aralkyl-substituted phenyl-α-naphthylamines, alkylated p-phenylenediamines, tetramethyl-diaminodiphenylamines, etc.), phenolic antioxidants (e.g., 2-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, ... rt-butyl-p-cresol, 2,6-di-tert-butylphenol, 4,4'-methylenebis-(2,6-di-tert-butylphenol), 4,4'-thiobis(6-di-tert-butyl-o-cresol), etc.), sulfur-based antioxidants (e.g., dilauryl-3,3'-thiodipropionate, sulfurized phenolic antioxidants, etc.), phosphorus-based antioxidants (e.g., phosphites, etc.), zinc dithiophosphate, oil-soluble copper compounds, and combinations thereof. The amount of antioxidant can vary from about 0.01 to about 10% by weight, from about 0.05 to about 5% by weight, or from about 0.1 to about 3% by weight, based on the total weight of the lubricating oil composition. Some suitable antioxidants are described in Leslie R. Rudnick, "Lubricant Additives: Chemistry and Applications," New York, Marcel Dekker, Chapter 1, pages 1-28 (2003), which is incorporated herein by reference.

[0067] The lubricating oil compositions disclosed herein may optionally contain a pour point depressant, which can lower the pour point of the lubricating oil composition. Any pour point depressant known to those skilled in the art may be used in the lubricating oil composition. Non-limiting examples of suitable pour point depressants include polymethacrylate, alkyl acrylate polymers, alkyl methacrylate polymers, di(tetra-paraffinphenol) phthalate, condensates of tetra-paraffin phenol, condensates of chlorinated paraffins and naphthalene, and combinations thereof. In some embodiments, the pour point depressant includes ethylene-vinyl acetate copolymers, condensates of chlorinated paraffins and phenols, polyalkylstyrenes, and the like. The amount of pour point depressant may vary from about 0.01 wt. % to about 10 wt. %, from about 0.05 wt. % to about 5 wt. %, or from about 0.1 wt. % to about 3 wt. %, based on the total weight of the lubricating oil composition. Some suitable pour point depressants are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London, Springer, Chapter 6, pages 187-189 (1996); and Leslie R. Rudnick, "Lubricant Additives: Chemistry and Applications," New York, Marcel Dekker, Chapter 11, pages 329-354 (2003), both of which are incorporated herein by reference.

[0068] The lubricating oil compositions disclosed herein may optionally contain a foam inhibitor or anti-foaming agent capable of breaking down foam in the oil. Any foam inhibitor or anti-foaming agent known to those skilled in the art may be used in the lubricating oil compositions. Non-limiting examples of suitable anti-foaming agents include silicone oils or polydimethylsiloxanes, fluorosilicones, alkoxylated aliphatic acids, polyethers (e.g., polyethylene glycols), branched polyvinyl ethers, alkyl acrylate polymers, alkyl methacrylate polymers, polyalkoxyamines, and combinations thereof. In some embodiments, the anti-foaming agent includes glycerol monostearate, polyglycol palmitate, trialkylmonothiophosphate, esters of sulfonated ricinoleic acid, benzoylacetone, methyl salicylate, glycerol monooleate, or glycerol dioleate. The amount of anti-foaming agent can vary from about 0.0001 to about 1 weight percent, from about 0.0005 to about 0.5 weight percent, or from about 0.001 to about 0.1 weight percent, based on the total weight of the lubricating oil composition. Some suitable anti-foaming agents are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London, Springer.

[0069] The lubricating oil compositions disclosed herein may optionally contain a rust inhibitor capable of inhibiting corrosion of ferrous metal surfaces. Any rust inhibitor known to those skilled in the art may be used in the lubricating oil compositions. Non-limiting examples of suitable rust inhibitors include oil-soluble monocarboxylic acids (e.g., 2-ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, cerotic acid, etc.), oil-soluble polycarboxylic acids (e.g., those derived from tall oil fatty acids, oleic acid, linoleic acid, etc.), alkenyl succinic acids in which the alkenyl group contains 10 or more carbon atoms (e.g., tetrapropenyl succinic acid, tetradecenyl succinic acid, hexadecenyl succinic acid, etc.), long-chain alpha, omega-dicarboxylic acids having molecular weights ranging from 600 to 3,000 daltons, and combinations thereof. The amount of rust inhibitor can vary from about 0.01 to about 10 weight percent, from about 0.05 to about 5 weight percent, or from about 0.1 to about 3 weight percent, based on the total weight of the lubricating oil composition.

[0070] Other non-limiting examples of suitable rust inhibitors include nonionic polyoxyethylene surfactants such as polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ethers, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene octylstearyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate. Further non-limiting examples of suitable rust inhibitors include stearic acid and other fatty acids, dicarboxylic acids, metal soaps, fatty acid amine salts, metal salts of heavy sulfonic acids, partial carboxylic acid esters of polyhydric alcohols, and phosphoric acid esters.

[0071] In some embodiments, the lubricating oil composition comprises at least one multifunctional additive. Some non-limiting examples of suitable multifunctional additives include sulfurized oxymolybdenum dithiocarbamates, sulfurized oxymolybdenum organophosphorodithioates, oxymolybdenum monoglycerides, oxymolybdenum diethylate amides, amine-molybdenum complex compounds, and sulfur-containing molybdenum complex compounds.

[0072] In certain embodiments, the lubricating oil composition comprises at least a viscosity index improver. Some non-limiting examples of suitable viscosity index improvers include polymethacrylate-type polymers, ethylene-propylene copolymers, styrene-isoprene copolymers, hydrated styrene-isoprene copolymers, polyisobutylene, and dispersant-type viscosity index improvers.

[0073] In some embodiments, the lubricating oil composition comprises at least a metal deactivator. Some non-limiting examples of suitable metal deactivators include disalicylidene propylene diamine, triazole derivatives, thiadiazole derivatives, and mercaptobenzimidazole.

[0074] The additives disclosed herein may be in the form of an additive concentrate containing multiple additives. The additive concentrate may contain a suitable diluent, such as a hydrocarbon oil of suitable viscosity. Such a diluent may be selected from the group consisting of natural oils (e.g., mineral oils), synthetic oils, and combinations thereof. Some non-limiting examples of mineral oils include paraffin-based oils, naphthene-based oils, asphalt-based oils, and combinations thereof. Some non-limiting examples of synthetic base oils include polyolefin oils (especially hydrogenated alpha-olefin oligomers), alkylated aromatics, polyalkylene oxides, aromatic ethers, and carboxylate esters (especially diester oils), and combinations thereof. In some embodiments, the diluent is a light hydrocarbon oil (both natural and synthetic). Typically, the diluent oil may have a viscosity of about 13 centistokes to about 35 centistokes at 40°C.

[0075] Generally, it is desirable for the diluent to readily solubilize the lubricating oil-soluble additive of the present invention to provide an oil additive concentrate that is readily soluble in the lubricating base oil stock or fuel, and not introduce any undesirable properties, including, for example, high volatility, high viscosity, and impurities such as heteroatoms, into the lubricating base oil stock and, ultimately, the finished lubricant or fuel.

[0076] The present invention further provides an oil soluble additive concentrate composition comprising an inert diluent and 2.0% to 90% by weight, preferably 10% to 50% by weight, of the oil soluble additive composition according to the present invention, based on the total concentrate.

[0077] The following examples are provided to illustrate embodiments of the present invention and are not intended to limit the invention to the specific embodiments shown. Unless otherwise indicated, all parts and percentages are by weight. All numerical values ​​are approximate. When numerical ranges are given, it should be understood that embodiments outside the stated ranges may still fall within the scope of the invention. The specific details described in each example should not be construed as necessary features of the invention. [Example]

[0078] The following non-limiting examples are illustrative of the present invention.

[0079] Lubricating oil compositions for evaluating their performance were prepared from the additives described below.

[0080] Comparative lubricating oil compositions (C-1 to C-9) and inventive examples (I-1 to I-8) were prepared from the additives described below in the amounts (wt %) set forth in Table 2. R-1 is a commercially available Dexron-VI ATF package, and R-2 is a commercially available Ford Mercon ATF package, so their exact contents and ratios are unknown.

[0081] The phosphite ester is an aryl phosphite (P: 13.3 wt %). The phosphoric acid is inorganic phosphoric acid (P: 27% by weight). The phosphorus additive is an alkyl phosphate amine salt (P: 8.2 wt %, N: 1.8 wt %). The sulfur EP additive A is a branched dialkyl thiadiazole compound (S: 34.0% by weight, N: 6.0% by weight). Sulfur EP additive B is a linear dialkyl thiadiazole compound (S: 31.0 wt %, N: 4.5 wt %). Corrosion inhibitor A is an alkylated benzotriazole compound (N: 14.6 wt %). Corrosion inhibitor B is a benzotriazole compound (N: 31.6 wt %). Other additives are dispersants, friction modifiers, antioxidants, sealant swell agents, and foam inhibitors.

[0082] Wear scar test The anti-wear performance of each lubricating oil composition was determined according to the four-ball wear scar test ASTM D4172 under conditions of 1800 rpm, 80°C oil temperature, and 392 N load for 60 minutes. After the test, the test balls were removed and the wear scars were measured. The wear scar diameters are reported in mm in Table 1. Specifically, if the wear scar diameter is 0.55 mm or less, the sample oil exhibits desirable wear performance.

[0083] Extreme pressure wear test The extreme pressure wear performance of lubricating oil compositions was determined using the Falex Pin and V-Block Test (ASTM D3233, Method B; pin material: SAE 3135 steel; block: AISI-C-1137 steel). This method involves operating a steel journal rotating at 290 rpm against two fixed V-blocks immersed in a lubricant sample. A load is applied to the V-blocks by a ratchet mechanism. In Test Method B, the load is applied in 250-lbf (1112-N) increments, and the load is held constant for 1 minute at each load increment. The resulting breaking load value is a measure of the level of load retention characteristics. Specifically, a breaking load of 1000 lbs or greater indicates that the sample oil exhibits desirable wear performance.

[0084] Cu corrosion test The Cu corrosion resistance of the lubricating oil compositions was determined using the Indiana Stirring Oxidation Test (ISOT, Test method JIS K 2514, in which two catalyst plates (copper and steel) and a glass varnish rod are immersed in the test oil, and the test oil is heated to 165.5°C and exposed to air by stirring for 150 hours). The increase in Cu content of the test oil was measured and reported in ppm in Table 1. Specifically, if the Cu content of the oil is 50 ppm or less, the sample oil exhibits desirable anti-corrosion performance. Also, the appearance of sludge or varnish formation indicates poor oxidation-corrosion performance.

[0085] volume resistivity The electrical insulating capacity of the lubricating oil compositions was determined in accordance with JIS C2101-1999-24. The volume resistivity of the test oils was measured at 80°C and an applied voltage of 250 V and reported in Ω cm. 9 A volume resistivity of Ω·cm or more is sufficiently high for electric vehicle applications.

[0086] [Table 1]

[0087] Test oil evaluation Comparative Examples C-3 and C-4 demonstrate that the use of phosphite antiwear additives, with or without phosphoric acid, respectively, does not provide sufficient antiwear performance, as evidenced by the poor wear results. C-5 shows that the addition of phosphate amine improves antiwear and extreme pressure performance somewhat, but is still insufficient. The addition of sulfur EP additives in C-6 results in good wear and EP performance, but has a negative impact on copper corrosion performance, as evidenced by the high level of Cu corrosion (483 ppm Cu). Meanwhile, C-7 shows that the corrosion inhibitor alone provides good Cu corrosion results, but is insufficient to achieve adequate wear performance.

[0088] Inventive Examples I-1 through I-8 demonstrate that balancing sulfur antiwear additives with corrosion inhibitors is important to achieve both excellent antiwear performance and Cu corrosion control. Inventive Examples I-7 and I-8, formulated with a mixture of Gp II and Gp III base oils, also provided adequate wear and corrosion protection.

[0089] Inventive Example I-9 was formulated with lower treatment rates of phosphorus additive and dispersant to demonstrate the effect on volume resistivity. As shown in Newcomb, T., "Electrical Conductivity of New and Used Automatic Transmission Fluids," SAE Int. J. Fuel Lubr. 9(3):2016, doi:10.4271 / 2016-01-2205, metal-containing detergents have the greatest impact on bulk fluid electrical conductivity, but other additives, such as small molecule antiwear additives and dispersants, also affect volume resistivity. Inventive Example I-9 demonstrates that reducing the amount of such polar additives can increase the volume resistivity of a lubricating composition while still maintaining good antiwear and copper corrosion protection.

[0090] Comparative Examples C-8 and C-9 were formulated to determine the maximum acceptable thresholds for corrosion inhibitor and sulfur EP additive, respectively. C-8 demonstrates that overdosing with corrosion inhibitor leads to poor antiwear performance. C-9 demonstrates that at 1700 ppm sulfur, black deposits formed on the surface of the Cu strip and within the test cell, indicating severe corrosion.

[0091] To better understand the effect of ionic contaminants on the volume resistivity of lubricating compositions, Inventive Example I-9 was modified with the addition of small amounts of metal-containing additives. A calcium detergent, a molybdenum-containing friction modifier, and a ZnDTP antiwear additive were added to Comparative Examples I-10, I-11, and I-12, respectively. The concentrations of Ca, Mo, and Zn in I-10, I-11, and I-12 were all approximately 50 ppm.

[0092] [Table 2]

[0093] Examples I-10 to I-12 demonstrate that the presence of 50 ppm of metal in a lubricating oil composition has only a small effect on volume resistivity. Even with 50 ppm of metal contamination, the volume resistivity of example oils I-10 to I-12 is less than 1.0 x 10 at 80°C. 9 These examples show that small amounts of metallic contamination can be tolerated without dramatically affecting the volume resistivity.

[0094] It is understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. For example, the functions described above and implemented as the best mode for operating the invention are for illustrative purposes only. Other configurations and methods may be implemented by those skilled in the art without departing from the scope and spirit of the invention. Moreover, those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. The following [1] to

[18] are all embodiments of the present invention. [1] A lubricating oil composition for battery electric vehicles (BEVs), hybrid vehicles (HVs) and plug-in hybrid vehicles (PHVs) having an electric motor and / or generator, comprising: a. Approximately 1.5 to 20 mm at 100°C 2 a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of / s; b. a phosphorus antiwear additive selected from inorganic phosphoric acids, acid or neutral phosphite esters, acid or neutral phosphate esters and their amine salts, or combinations thereof; c. a nitrogen-based corrosion inhibitor, wherein the total amount of nitrogen provided by the corrosion inhibitor to the lubricating oil composition is 125 ppm or less, based on the weight of the lubricating oil composition; d. a sulfur EP additive, wherein the total amount of sulfur provided by the sulfur EP additive to the lubricating oil composition is 300 to 1500 ppm by weight of the lubricating oil composition; and the lubricating oil composition contains less than 50 ppm metals and has a 1.0 x 10 9 The lubricating oil composition has a volume resistivity of greater than Ω·cm. [2] [1] The lubricating oil composition according to [1], wherein the phosphorus anti-wear additive is a phosphite ester, a phosphate amine, a phosphoric acid, or a combination thereof. [3] The lubricating oil composition according to [2], wherein the phosphorus anti-wear additive provides 100 to 1000 ppm of phosphorus to the lubricating oil composition. [4] The corrosion inhibitor has the following structure:

change

change

[10] 1. A method for reducing corrosion and improving wear protection in a transmission system of a battery electric vehicle (BEV), hybrid vehicle (HV), and plug-in hybrid vehicle (PHV) having an electric motor and / or generator, comprising: a. Approximately 1.5 to 20 mm at 100°C 2 a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of / s; b. a phosphorus antiwear additive selected from inorganic phosphoric acids, acid or neutral phosphite esters, acid or neutral phosphate esters and their amine salts, or combinations thereof; c. a nitrogen-based corrosion inhibitor, wherein the total amount of nitrogen provided by the corrosion inhibitor to the lubricating oil composition is 125 ppm or less, based on the weight of the lubricating oil composition; d. a sulfur EP additive, wherein the total amount of sulfur provided by the sulfur EP additive to the lubricating oil composition is 300 to 1500 ppm by weight of the lubricating oil composition; wherein the lubricating oil composition contains less than 50 ppm of metals and has a % CI of 1.0 x 10 at 80°C. 9 The method has a volume resistivity of greater than Ω·cm.

[11]

[10] The method of

[10] , wherein the phosphorus anti-wear additive is a phosphate ester, a phosphate amine, a phosphoric acid, or a combination thereof.

[12] The method of

[11] , wherein the phosphorus anti-wear additive provides 100 to 1000 ppm of phosphorus to the lubricating oil composition.

[13] The corrosion inhibitor has the following structure:

change

[10] ,

[14]

[10] The method of

[10] , wherein the corrosion inhibitor is an alkylated benzotriazole compound, a benzotriazole compound, or a combination thereof.

[15] The method according to

[10] , wherein the total amount of nitrogen provided by the corrosion inhibitor in the lubricating oil composition is 20 to 125 ppm based on the weight of the lubricating oil composition.

[16] The sulfur EP additive has the following structure:

change

[10] ,

[17]

[10] The method of

[10] , wherein the sulfur EP additive is a branched dialkyl thiadiazole compound, a linear dialkyl thiadiazole compound, or a combination thereof.

[18] The method of

[10] , wherein the total amount of sulfur provided to the lubricating oil composition by the sulfur EP additive is 300 to 1200 ppm based on the weight of the lubricating oil composition.

Claims

1. 1. A lubricating oil composition for battery electric vehicles (BEVs), hybrid vehicles (HVs), and plug-in hybrid vehicles (PHVs) having an electric motor and / or generator, comprising: a. 1.5 to 20 mm at 100°C ２ at least 50 wt. % of an oil of lubricating viscosity having a kinematic viscosity in the range of 1 / s; b. 300 to 390 ppm total phosphorus from one or more phosphorus anti-wear additives selected from aryl phosphites, inorganic phosphoric acids, alkyl phosphate amine salts, or combinations thereof; c. a nitrogen-based corrosion inhibitor, wherein the total amount of nitrogen provided by the corrosion inhibitor to the lubricating oil composition is from 40 to 100 ppm, based on the weight of the lubricating oil composition, and the nitrogen-based corrosion inhibitor is an alkylated benzotriazole compound or a benzotriazole compound; d. a sulfur EP additive, wherein the total amount of sulfur provided by the sulfur EP additive to the lubricating oil composition is 300 to 1050 ppm, based on the weight of the lubricating oil composition, and the sulfur EP additive is a branched dialkyl thiadiazole compound or a linear dialkyl thiadiazole compound; and the lubricating oil composition contains less than 50 ppm metals and has a pH of 1.0 x 10 at 80°C. ９ The lubricating oil composition has a volume resistivity of greater than Ω·cm.

2. The corrosion inhibitor has the following structure: 【Chemical 1】 (In the formula, R ３ is a hydrogen or hydrocarbyl group containing 1 to 20 carbon atoms, optionally containing oxygen, sulfur, or nitrogen atoms. The lubricating oil composition of claim 1, having

3. The sulfur EP additive has the following structure: 【Chemistry 2】 (In the formula, R １ and R ２ are each independently a hydrogen atom or a hydrocarbyl moiety containing 6 to 18 carbon atoms, m is 2, and n=2. The lubricating oil composition of claim 1, having

4. 1. A method for reducing corrosion and improving wear protection in a transmission system of a battery electric vehicle (BEV), hybrid vehicle (HV), and plug-in hybrid vehicle (PHV) having an electric motor and / or generator, comprising: lubricating and operating said transmission system with a lubricating oil composition; The lubricating oil composition a. 1.5 to 20 mm at 100°C ２ at least 50 wt. % of an oil of lubricating viscosity having a kinematic viscosity in the range of 1 / s; b. 300 to 390 ppm total phosphorus from one or more phosphorus anti-wear additives selected from aryl phosphites, inorganic phosphoric acids, alkyl phosphate amine salts, or combinations thereof; c. a nitrogen-based corrosion inhibitor, wherein the total amount of nitrogen provided by the corrosion inhibitor to the lubricating oil composition is from 40 to 100 ppm, based on the weight of the lubricating oil composition, and the nitrogen-based corrosion inhibitor is an alkylated benzotriazole compound or a benzotriazole compound; d. a sulfur EP additive, wherein the total amount of sulfur provided by the sulfur EP additive to the lubricating oil composition is 300 to 1050 ppm, based on the weight of the lubricating oil composition, and the sulfur EP additive is a branched dialkyl thiadiazole compound or a linear dialkyl thiadiazole compound; Including, The lubricating oil composition contains less than 50 ppm metals and has a pH of 1.0 x 10 at 80°C. ９ The method of any preceding claim, wherein the material has a volume resistivity of greater than Ω cm.

5. The corrosion inhibitor has the following structure: 【Chemistry 3】 (In the formula, R ３ is a hydrogen or hydrocarbyl group containing 1 to 20 carbon atoms, optionally containing oxygen, sulfur, or nitrogen atoms.

5. The method of claim 4, comprising:

6. The sulfur EP additive has the following structure: 【Chemistry 4】 (In the formula, R １ and R ２ are each independently a hydrogen atom or a hydrocarbyl moiety containing 6 to 18 carbon atoms, m is 2, and n=2.

5. The method of claim 4, comprising:

Images