Lubricating oil composition for electric vehicles

Abstract

A lubricating oil composition for a motor vehicle equipped with an electric motor and / or generator is provided. The lubricating oil composition has a viscosity of about 1.5 mm at 100° C. 2 / s~approx.20mm 2 a. a major amount of an oil of lubricating viscosity having a kinematic viscosity in the range of 100 / s; and b. a sulfur-based additive comprising a thiadiazole and a sulfurized polyolefin of formula (I), [Formula 1] TIFF2024543519000021.tif53165 wherein R1 is hydrogen or methyl, R2 is a C8-C40 hydrocarbyl group, and the sulfur-based additive comprises a sulfur-based additive that provides sulfur to the lubricating oil composition in an amount of 0.01 wt% to 0.2 wt% based on the total weight of the lubricating oil composition, c. a phosphorus compound, and d. a boron-containing ashless polyisobutenyl succinimide-based dispersant. The lubricating oil composition provides excellent volume resistivity, detergency, thermal and oxidative stability, antiwear properties, and corrosion resistance at high temperatures.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 280,007, filed November 16, 2021, which is incorporated by reference in its entirety.

[0002] The present disclosure relates generally to automotive transmissions, and in particular to transmissions in electric vehicles (EVs), such as e-axles and hybrid vehicles (HVs), and lubricant compositions. [Background technology]

[0003] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. As such, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0004] Electric vehicles (EVs), including battery electric vehicles (BEVs), hybrid electric vehicles (HVs), and plug-in hybrid vehicles (PHVs) with electric motors and / or generators integrated into the drivetrain, present unique challenges to the lubricant industry.

[0005] One of the challenges in electric and hybrid vehicles 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 electric and hybrid vehicles present challenges with wear protection. While phosphorus and sulfur-based additives may provide wear protection, sulfur compounds may oxidize to acidic species at high temperatures and contribute to increased corrosion. This is especially detrimental in electric or hybrid vehicles where copper is present in many electrical systems in the powertrain and may begin to corrode at high temperatures. Thus, lubricants used in the lubrication of these vehicles may provide sufficient copper corrosion protection to minimize corrosion.

[0006] Furthermore, the electromagnets used to drive the motor cause copper losses (losses due to electrical resistance of the copper wires in the motor), which in turn cause heat to occur in the enamelled wires (magnetic wires) in the motor. In the case of electric vehicles, the lubricating oil used in the transmission is sprayed directly onto the enamelled wires (oil cooling) to cool them down. This oil cooling has very good cooling efficiency, but since the oil comes into direct contact with the surface of the hot enamelled wires, high-temperature deposits may form if highly reactive extreme pressure agents are used in the lubricating oil. The deposits accumulate around the enamelled wires, which reduces the cooling efficiency and causes damage.

[0007] Volume resistivity (the fluid's resistance to electrical current) can also be an issue. If the resistivity is too low, the powertrain may leak charge and become less efficient. If it is too high, static charge buildup may cause arcing in the vehicle's electrical components. The presence of metal ions reduces the volume resistivity of the fluid. Thus, metals commonly used in lubricants for conventional internal combustion engines, such as Ca, Mo, and Zn, may be minimized in electric vehicles to meet volume resistivity requirements.

[0008] Given the complexities associated with lubricating electric and hybrid vehicles, a need exists for lubricants that balance wear protection with good copper corrosion resistance, sufficient volume resistivity, and good hot surface deposit control. Summary of the Invention

[0009] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these specific embodiments, and that these aspects are not intended to limit the scope of the present disclosure. In fact, the present disclosure may encompass a variety of aspects that may not be described below.

[0010] The disclosed embodiments relate to lubricating oil compositions suitable for use in automotive transmissions, particularly in electric and hybrid vehicle transmissions, that exhibit high wear protection, good copper corrosion resistance, sufficient volume resistivity, and good hot surface deposit control.

[0011] According to one embodiment of the present disclosure, there is provided a lubricating oil composition for use in an automotive vehicle equipped with an electric motor and / or generator, the lubricating oil composition comprising: a. At 100℃, about 1.5mm 2 / s~approx.20mm 2 a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of 1 / s; b. A sulfur-based additive comprising a thiadiazole and a sulfurized polyolefin of formula (I), [ka] wherein R1 is hydrogen or methyl and R2 is a C8 to C40 hydrocarbyl group, the sulfur-based additive providing sulfur to the lubricating oil composition in an amount of 0.01 wt. % to 0.2 wt. %, based on the total weight of the lubricating oil composition; C. a phosphorus compound; d. A boron-containing ashless polyisobutenyl succinimide dispersant.

[0012] According to another embodiment of the present disclosure, there is provided a method for reducing corrosion and improving wear protection in a transmission system of a motor vehicle having an electric motor and / or generator by lubricating the transmission system with a lubricating oil composition comprising: a. At 100℃, about 1.5mm 2 / s~approx.20mm 2 a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of 1 / s; b. A sulfur-based additive comprising a thiadiazole and a sulfurized polyolefin of formula (I), [ka] wherein R1 is hydrogen or methyl and R2 is a C8 to C40 hydrocarbyl group, the sulfur-based additive providing sulfur to the lubricating oil composition in an amount of 0.01 wt. % to 0.2 wt. %, based on the total weight of the lubricating oil composition; C. a phosphorus compound; d. A boron-containing ashless polyisobutenyl succinimide dispersant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] As mentioned above, unlike conventional vehicles powered by internal combustion engines, in electric vehicles the same lubricating fluid is shared by the electric motor and the transmission. This creates unique challenges for lubricating the transmission in these types of vehicles. One particular challenge facing the lubricant industry is that certain lubricant additives may be useful for wear and seizure protection, but over time may also contribute to increased corrosion.

[0014] As an example, when a lubricant is new, corrosion of non-ferrous metals, especially copper, due to extreme pressure (EP) and anti-wear additives (which produce acidic breakdown products) is prevented by the effect of the corrosion inhibitors. However, as the lubricant is used over time, the oil deteriorates and the corrosion inhibitors are depleted. This accelerates the rate of corrosion of non-ferrous metals due to oxidative breakdown products from the EP and anti-wear additives.

[0015] As described in detail herein, the inventors have discovered a particular combination of lubricant components useful in lubricating EV and hybrid vehicle transmissions that allows for extended use of the lubricant, which exhibits good thermal and oxidative stability, and slows the corrosion rate of non-ferrous metals even as the oil ages and the corrosion inhibitors become depleted.

[0016] Definition: The following terms are used throughout the specification and have the following meanings unless otherwise stated.

[0017] The term "major amount" of base oil refers to an amount of base oil that is at least 40 wt% of a lubricant 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 a lubricant composition.

[0018] The term "minor amount" of an additive refers to an amount of the additive that is 40% or less by weight of the lubricating oil composition. In some embodiments, a "minor amount" of an additive refers to an amount of the additive that is 40% or less by weight, 30% or less by weight, or 20% or less by weight of the lubricating oil composition.

[0019] The term "substantially free" of metals refers to levels of metals present in a lubricating oil composition at or below 50 ppm.

[0020] The term "ashless" in reference to an additive to a lubricating oil composition means that the additive does not contain metals.

[0021] The term "Total Base Number" or "TBN" refers to the level of alkalinity in a lubricant sample and indicates the ability of a lubricant 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 in mgKOH / g (equivalent to the number of milligrams of KOH required to neutralize one gram of product). Thus, a high TBN reflects a more overbased product and, therefore, a higher base reserve to neutralize acids.

[0022] The term "PIB" refers to polyisobutylene.

[0023] lubricating viscosity oil The lubricating oil composition disclosed herein generally comprises at least one oil of lubricating viscosity. Any base oil known to those skilled in the art may be used as the oil of lubricating viscosity disclosed herein. Some base oils suitable for preparing the lubricating oil composition are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London, Springer, Chapters 1 and 2 (1996); 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. Generally, the lubricating oil composition has a major amount of base oil in the lubricating oil composition, and in some embodiments may comprise about 70 wt.% to about 99.5 wt.% of base oil, based on the total weight of the lubricating oil composition. In some embodiments, the amount of base oil in the lubricating oil composition is from about 40 wt%, 50 wt%, 60 wt%, 70 wt%, 75 wt%, 80 wt%, or 85 wt% to about 90 wt%, 98 wt%, 98.5 wt%, or 99 wt%, based on the total weight of the lubricating oil composition.

[0024] In certain embodiments, the oil of lubricating viscosity, also referred to as base oil or base stock, is or comprises any natural or synthetic lubricating oil base oil fraction. Some non-limiting examples of synthetic oils include oils such as polyalphaolefins or PAOs prepared from the polymerization of at least one alpha olefin, such as ethylene, or from a hydrocarbon synthesis procedure using carbon monoxide and hydrogen gas, such as the Fischer-Tropsch process. In certain embodiments, the base oil comprises less than about 10 wt.% of one or more heavy fractions, based on the total weight of the base oil. Heavy fraction refers to an oil fraction having a viscosity of at least about 20 cSt at 100° C. In certain embodiments, the heavy fraction has 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 yet a further embodiment, the base oil is free of heavy fractions.

[0025] Lubricating oil compositions typically comprise a major amount of an oil of lubricating viscosity. In some embodiments, the oil of lubricating viscosity 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. The kinematic viscosity of the oil of lubricating viscosity disclosed herein can be measured according to ASTM D 445, which is incorporated herein by reference.

[0026] In other embodiments, the oil of lubricating viscosity 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, distillation, 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 manufacture, contamination, or prior use.

[0027] In some embodiments, the oil of lubricating viscosity comprises one or more of base stocks in one or more of Groups I-V, as specified 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), which is incorporated herein by reference. The API guidelines define base stocks as lubricating components that can be produced using a variety of different processes. Groups I, II, and III base stocks are mineral oils, each with a specific range of saturates content, sulfur content, and viscosity index. Group IV base stocks are polyalphaolefins (PAOs). Group V base stocks include all other base stocks not included in Groups I, II, III, or IV.

[0028] In some embodiments, the oil of lubricating viscosity comprises one or more base stocks from Group I, II, III, IV, V, or combinations thereof. In other embodiments, the oil of lubricating viscosity comprises one or more base stocks from Group II, III, IV, or combinations thereof. In certain embodiments, the oil of lubricating viscosity has a kinematic viscosity at 100° C. of about 1.5 cSt to about 20 cSt, about 2 cSt to about 20 cSt, or about 2 cSt to about 16 cSt. According to an exemplary embodiment, the oil of lubricating viscosity comprises a mixture of a Group II base stock and a Group III base stock.

[0029] The oil of lubricating viscosity (base oil) may also be selected from the group consisting of natural oils of lubricating viscosity, synthetic oils of lubricating viscosity, and mixtures thereof. In some embodiments, the base oil includes 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 oil of lubricating viscosity includes oils derived from natural oils such as animal oils, vegetable oils, mineral oils (e.g., processed liquid petroleum oils and solvent or acid treated mineral oils of the paraffinic, naphthenic, or mixed paraffinic-naphthenic types), 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 liver 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.

[0030] In some embodiments, synthetic oils of lubricating viscosity include hydrocarbon oils and halo-substituted hydrocarbon oils, such as polymerized and copolymerized olefins, alkylbenzenes, alkylated naphthalenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl sulfides, and derivatives, analogs, and congeners thereof. In other embodiments, synthetic oils include alkylene oxide polymers, interpolymers, copolymers, and derivatives thereof, where the terminal hydroxyl groups may be modified by esterification, etherification, and the like. In further embodiments, synthetic oils include esters of dicarboxylic acids with various alcohols. In certain embodiments, synthetic oils include C5-C 12 These include 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.

[0031] In some embodiments, synthetic oils of lubricating viscosity include silicon-based oils (e.g., polyalkyl-, 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.

[0032] Base oils derived from the hydroisomerization of wax may also be used, either alone or in combination with the natural and / or synthetic base oils described above. Such wax isomerate oils are produced by the hydroisomerization of natural or synthetic waxes or mixtures thereof over a hydroisomerization catalyst.

[0033] In further embodiments, the base oil comprises a poly-alpha-olefin (PAO). Typically, the poly-alpha-olefin may be derived from an alpha-olefin having from about 2 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 have a viscosity at 100° C. of from about 1.5 cSt to about 15 cSt, from about 1.5 cSt to about 12 cSt, or from about 1.5 cSt to about 8 cSt. In some examples, the poly-alpha-olefins may be used with other base oils, such as mineral oils.

[0034] In further embodiments, the base oil comprises a polyalkylene glycol or polyalkylene glycol derivative, in which the terminal hydroxyl group 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), 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.

[0035] In further embodiments, the base oil may include 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.

[0036] In a further embodiment, the base oil may comprise hydrocarbons prepared by the Fischer-Tropsch process, which uses a Fischer-Tropsch catalyst to prepare hydrocarbons from a gas 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 well known to those skilled in the art.

[0037] In further embodiments, the base oil comprises unrefined oil, refined oil, re-refined oil, or mixtures 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 retorting operations, petroleum-based oils obtained directly from primary distillation, and ester oils obtained directly from esterification processes and used without further treatment. Refined oils are similar to unrefined oils, except that the former have been further treated by one or more purification processes to improve one or more properties. Many such purification processes are well known to those skilled in the art, such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Re-refined oils are obtained by applying refining oil processes similar to those used to obtain refined oils. Such re-refined oils are also known as reclaimed or reprocessed oils, and are often additionally treated by processes aimed at removing spent additives and oil breakdown products.

[0038] Sulfur Additives The lubricating oil compositions of the present disclosure contain at least one sulfur-based additive, which may include thiadiazoles and / or sulfurized polyolefins as described below.

[0039] According to certain embodiments of the present disclosure, the one or more sulfur-based additives of the lubricating oil composition may include a sulfurized polyolefin, such as a sulfurized polyisobutylene (PIB). In one embodiment, the lubricating oil composition includes a sulfurized polyisobutylene oligomer made by reacting a highly reactive polyisobutylene (HR PIB) with sulfur. The sulfurized polyisobutylene oligomer has a sulfur content ranging from 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt% to 21 wt%, 22 wt%, 23 wt%, 24 wt%, or 25 wt%, for example, 20.6 wt%, based on the total weight of the sulfurized polyisobutylene oligomer. Examples of sulfurized PIB oligomers are described in U.S. Patent No. 7,414,013, the entire contents of which are incorporated herein by reference.

[0040] According to a particular embodiment, the sulfur-based additive comprises a sulfurized polyolefin of formula (I): [ka] In the formula, R1 is hydrogen or methyl, and R2 is a C8 to C40 hydrocarbyl group.

[0041] As a non-limiting example, the sulfurized polyolefin of formula (I) may be a sulfurized polyisobutylene oligomer of formula (II): [ka] wherein R1 is hydrogen or methyl, m is an integer from 1 to 9, and n is 0 or 1, with the proviso that when n is 0, R1 is methyl, and when n is 1, R1 is hydrogen. In one embodiment, m is an integer from 1 to 6, e.g., 1 to 5, and n is 1. In another aspect, m is greater than 1, e.g., an integer from 2 to 5, and n is 1.

[0042] According to certain embodiments of the present disclosure, the sulfurized polyolefin of formula (I) is present in the lubricating oil composition in an amount of 0.05 wt%, 0.1 wt%, or 0.13 wt% to 0.18 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, or 0.8 wt%, based on the total weight of the lubricating oil composition. In embodiments of the lubricating oil of the present disclosure, it has been found that the increased sulfur content provided by the sulfurized polyolefin of formula (I) may reduce the results of high temperature oxidation stability and anticorrosion tests. In such embodiments, the sulfurized polyolefin of formula (I) provides a lubricating oil composition with a sulfur content of 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.05 wt%, 0.06 wt%, up to 0.1 wt%, or up to 0.2 wt%, based on the total weight of the lubricating oil composition.

[0043] As mentioned above, the sulfur-based additive may include a thiadiazole compound in addition to or instead of the sulfurized polyolefin of formula (I). Indeed, in one embodiment, at least one sulfur-based additive includes both a sulfurized polyolefin of formula (I) and a thiadiazole compound. The thiadiazole compound provides good resistance to wear, particularly between metal and metal surfaces. Examples of thiadiazole compounds include 1,3,4-thiadiazole, 1,2,4-thiadiazole, and 1,4,5-thiadiazole. In an embodiment in which the sulfur-based additive includes a thiadiazole, the thiadiazole may have a sulfur content in the range of 30.0% to 40.0% by weight, for example, 34.0% by weight, based on the total weight of the thiadiazole. The thiadiazole may be present in an amount of, for example, 0.005 wt.%, or 0.01 wt.% to 0.03 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, or 0.5 wt.%, based on the total weight of the lubricating oil composition. The thiadiazole may be used as a corrosion inhibitor in the range of 0.005 wt.% to 0.05 wt.%, and may be used up to about 0.5 wt.% to improve antiwear and EP performance. In some embodiments, a sulfide film is formed on the lubricated surface to prevent corrosion and provide antiwear, but if too much is used, sludge may form immediately. According to this embodiment, the thiadiazole provides a lubricating oil with a sulfur content of 0.005 wt.% to 0.2 wt.%, based on the total weight of the lubricating oil composition.

[0044] In certain embodiments, the thiadiazole compound is a 1,3,4-thiadiazole, for example, a 2,5-bis(hydrocarbylmercapto)-1,3,4-thiadiazole, as defined by formula (III) below. [ka] In the above structure, R3 and R4 each represent an alkyl group having 1 to 30 carbon atoms, e.g., 6 to 18 carbon atoms. The alkyl group may be straight or branched. R3 and R4 may be the same or different from each other. Furthermore, n and m are, independently, 1 or 2. Specific examples of alkyl groups represented by R3 and R4 in the above general structure include methyl, ethyl, or any straight chain (n-), secondary (sec-), terminally branched (iso-) or tertiary (tert-) alkyl group having 3 to 30 carbon atoms.

[0045] In one embodiment, the sulfur-based additive is present in a total amount of 0.01 wt%, 0.05 wt%, 0.08 wt%, or 0.09 wt%, up to 0.8 wt%, 0.75 wt%, 0.7 wt%, 0.6 wt%, or 0.5 wt%, for example, 0.8 wt%, based on the total weight of the lubricating oil composition. As mentioned above, if the sulfur content of the lubricating oil composition is too high, it may reduce the results of high temperature oxidation stability and anti-corrosion test. Furthermore, if additives containing a large amount of sulfur are used, thermal and oxidation stability will decrease and corrosion will worsen. In particular, if excessive sulfur is introduced into the composition, copper dissolution will begin. To achieve the benefits of the sulfur-based additive described herein, according to the present embodiments, the sulfur-based additive provides sulfur to the lubricating oil composition in a total amount of 0.01 wt %, 0.02 wt %, 0.03 wt %, 0.04 wt %, or 0.05 wt % to 0.1 wt %, 0.15 wt %, or 0.2 wt %, based on the total weight of the lubricating oil composition.

[0046] The lubricating oil composition may contain one or more additional extreme pressure (EP) sulfur-based additives, which can protect sliding metal surfaces from seizure under extreme pressure conditions.In general, extreme pressure additives are compounds that can chemically combine with metals to form a surface film that prevents asperities facing metal surfaces from fusing under high loads.Examples of sulfur-based extreme pressure additives include sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiophosphate esters (thiophosphites and thiophosphates), alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, and dialkylthiodipropionate compounds.

[0047] Sulfur-based additives are typically ashless and therefore metal-free.

[0048] Phosphorus Additive The lubricating oil compositions of this disclosure also contain at least one phosphorus-containing additive, such as one or more phosphorus-containing anti-wear additives.

[0049] The at least one phosphorus additive may be an acid phosphate ester, a phosphoric acid ester, an amine salt of a phosphoric acid ester (amine phosphate), an acid phosphonic acid ester, a phosphonic acid ester, an acid phosphite, a phosphorous acid ester, and a phosphoric acid. For example, the phosphorous additive may include an acid or neutral phosphite, an acid or neutral phosphoric acid ester, and an amine salt thereof, a phosphonic acid ester, or a combination thereof. According to certain embodiments, the phosphorous additive includes a phosphonic acid, an amine phosphate, and / or a phosphorous acid ester. The at least one phosphorous additive may be present in an amount ranging from 0.005 wt%, 0.01 wt%, 0.03 wt%, 0.05 wt%, 0.10 wt%, or 0.20 wt% to 0.7 wt%, 0.6 wt%, 0.5 wt%, 0.40 wt%, 0.35 wt%, or 0.33 wt%, based on the total weight of the lubricating oil composition.

[0050] (a) Phosphonates Phosphonates are salts or esters of phosphonic acids. They contain a tetrahedral phosphorus center and are typically prepared from phosphorus-containing acids.

[0051] Diacid phosphonates are the result of deprotonation of a diacid, phosphonic acid. RPO(OH)2+NaOH→H2O+RPO(OH)(ONa) (monosodium phosphonate) RPO(OH)(ONa) + NaOH → H2O + RPO(ONa)2 (disodium phosphonate)

[0052] Phosphonates are the result of the condensation of a phosphonic acid with an alcohol and can be acidic or neutral. Neutral phosphonates have the formula R-PO(OR)2, while acidic phosphonates have the formula R-PO(OR) x (OH) y where x+y=2 and x, y=0, 1, or 2. In the above reaction diagrams and formulas for phosphonate esters, R represents a hydrocarbon group having 1 to 30 carbons.

[0053] According to an exemplary embodiment, the lubricating oil composition includes an alkyl phosphonate ester commercially available from Solvay Chemicals as Duraphos-100. More specifically, the alkyl phosphonate ester is dimethyloctadecyl phosphonate (C 18 H 37 -P(OCH3)2, which is an alkyl phosphonate ester containing 8.5 wt.% phosphorus, based on the total weight of the alkyl phosphonate. In certain embodiments, the alkyl phosphonate is present in an amount of 0.20 wt.%, 0.25 wt.%, or 0.27 wt.% to 0.7 wt.%, 0.6 wt.%, 0.5 wt.%, 0.40 wt.%, 0.35 wt.%, or 0.33 wt.%, based on the total weight of the lubricating oil composition.

[0054] (b) Phosphoric acids and amine phosphates The phosphate additive may alternatively or additionally comprise phosphoric acid, a phosphate ester, and / or an amine salt of a phosphate ester. Examples of amine salts of phosphate esters include amine salts of acidic alkyl phosphate esters, such as the acidic alkyl phosphate esters represented by Formula IV: (OR) x (OH) y P=O (IV) In the formula, x+y=3, and R represents an alkyl group having 1 to 30 carbons.

[0055] Specific examples of alkyl groups represented by R include straight or branched chain alkyl groups having 1 to 18, for example 1 to 12, carbon atoms, such as a methyl group, an ethyl group, or any straight chain (n-), secondary (sec-), terminally branched (iso-) or tertiary (tert-) alkyl group having 3 to 18 carbon atoms.

[0056] The amines used to generate the amine salts can be primary amines, secondary amines, tertiary amines, or tertiary alkyl primary amines. In addition, examples of the aforementioned amines include amines represented by formula (V): [ka] In the formula, R5, R6, and R7 are an aliphatic hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom, and at least one of R5, R6, and R7 is an aliphatic hydrocarbon group having 1 to 20 carbon atoms. Here, the aliphatic hydrocarbon group is typically 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 a straight chain, a branched chain, or a cyclic group. The above-mentioned aliphatic hydrocarbon is typically one having 6 to 20 carbon atoms, and more typically one having 12 to 20 carbon atoms. In certain embodiments, the amine is a primary amine in which the aliphatic hydrocarbon group has 12 to 20 carbon atoms, for example, a tertiary alkyl primary amine as disclosed in WO1995006094, the entirety of which is incorporated herein by reference.

[0057] In one embodiment, the phosphoric acid, phosphate ester, and / or amine salt of a phosphoric acid ester are present in a total amount of 0.1 wt %, or 0.2 wt % to 0.5 wt %, 0.4 wt %, or 0.35 wt %, based on the total weight of the lubricating oil composition.

[0058] Typically, the phosphoric acid, phosphoric acid ester, and / or amine salt of the phosphoric acid ester together have a phosphorus content of from 2.0% or 4.0% to 10.0% or 9.0% by weight, for example, 6.9% by weight, based on the total weight of the phosphoric acid, phosphoric acid ester, and / or amine salt of the phosphoric acid ester.

[0059] (c) Phosphorous acid The phosphorus additive may alternatively or additionally comprise a phosphorous acid, such as monohydrocarbyl phosphite, dihydrocarbyl phosphite, trihydrocarbyl phosphite. Trihydrocarbyl phosphite is also referred to as a phosphite ester. Examples of phosphorous acids used in accordance with the present embodiment include dihydrocarbyl hydrogen phosphite or phosphite ester.

[0060] In one embodiment, the phosphorus-containing anti-wear additive is a dihydrocarbyl hydrogen phosphite. The dihydrocarbyl hydrogen phosphite is represented by formula (VI): O=P(OR)2H (VI) In the formula, R represents a hydrocarbon group having 1 to 30 carbons.

[0061] 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.

[0062] In one embodiment, the phosphorus-containing anti-wear additive is a phosphite ester, which is represented by formula (VII): P(OR)3(VII) In the formula, R represents a hydrocarbon group having 1 to 30 carbons. The hydrocarbon group may have one or more heteroatoms, such as oxygen or sulfur. As an example, the hydrocarbon group may individually include an ether or a thioether in some embodiments. In one embodiment, the hydrocarbon group is a thioether.

[0063] Other specific examples of trihydrocarbyl phosphites include aryl trihydrocarbyl phosphites, such as triphenyl phosphite, tricresyl phosphite, trisnonylphenyl phosphite, diphenyl mono 2-ethylhexyl phosphite, and diphenyl mono tridecyl phosphite; and aliphatic trihydrocarbyl phosphites, such as tributyl phosphite, trioctyl phosphite, triisoctyl phosphite, tri(2-ethylhexyl) phosphite, trisdecyl phosphite, tristridecyl phosphite, trioleyl phosphite, trilauryl phosphite, and tristearyl phosphite.

[0064] According to exemplary embodiments, the phosphite is present at 0.05 wt %, 0.10 wt %, or 0.20 wt % to 1.0 wt %, 0.7 wt %, or 0.50 wt %, based on the weight of the lubricating oil composition.

[0065] According to exemplary embodiments, the phosphite has a phosphorus content of 5%, 9%, or 7% to 20%, 16%, or 14% by weight, based on the weight of the phosphite.

[0066] According to an exemplary embodiment, the phosphite is selected from dilauryl hydrogen phosphite having 7.2% by weight phosphorus, diphenyl hydrogen phosphite having 13.3% by weight phosphorus, and a phosphite-containing thioether alkyl group having 8% by weight phosphorus and 8.4% by weight sulfur, where the phosphorus and sulfur contents are based on the weight of the phosphite.

[0067] The phosphorus-based additive provides phosphorus to the lubricating oil composition such that the total amount of phosphorous acid in the composition is 0.005 wt.%, 0.01 wt.%, 0.02 wt.%, 0.03 wt.%, or 0.04 wt.% to 0.05 wt.%, 0.1 wt.%, or 0.2 wt.%, based on the total weight of the lubricating oil composition.

[0068] Corrosion Inhibitors The lubricating oil composition may also include a corrosion inhibitor, such as a nitrogen-containing corrosion inhibitor. The corrosion inhibitor may be a nitrogen-containing heterocyclic compound and its derivatives. In an exemplary embodiment, the corrosion inhibitor is a triazole, and the triazole typically does not include any active sulfate groups. For example, the corrosion inhibitor often includes alkyl and aryl derivatives of triazole, such as tolyltriazole. These may be substituted or unsubstituted. One example of a tolyltriazole compound has the following formula VIII: [ka] In the above formula, R8 represents hydrogen or an alkyl group having 1 to 30 carbons. R8 can be straight or branched chain, and it can be saturated or unsaturated. It can contain a ring structure that is alkyl or aromatic in nature. R8 can also contain heteroatoms such as N, O, or S.

[0069] Substituted triazoles 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 formaldehyde and reactive equivalents such as 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.

[0070] In one embodiment, the substituted triazole of the present disclosure is an alkyl-substituted triazole. In another embodiment, the substituted triazole is a benzotriazole.

[0071] According to one exemplary embodiment, the triazole is an N-alkyltolyltriazole containing 14.6% by weight nitrogen, based on the total weight of the triazole.

[0072] In one embodiment, the corrosion inhibitor is present in an amount of 0.1 wt.% or less, such as 0.01 wt.% or 0.02 wt.% to 0.05 wt.% or 0.04 wt.%, for example 0.03 wt.%, based on the weight of the total lubricating oil composition.

[0073] Dispersants The lubricating oil composition of the present disclosure may contain one or more ashless dispersants. Generally, the ashless dispersants are boron-containing or nitrogen-containing dispersants, such as dispersants formed by reacting alkenyl succinic anhydrides with amines. Examples of such dispersants are alkenyl succinimides and succinamides. These dispersants may be further modified, for example, by reaction with ethylene carbonate. Ester-based ashless dispersants derived from long-chain hydrocarbon-substituted carboxylic acids and hydroxy compounds may also be employed.

[0074] The ashless dispersant can be derived from polyisobutenyl succinic anhydride. These dispersants are commercially available. According to an exemplary embodiment, the lubricating oil composition includes a boron-containing polyisobutenyl succinimide as a dispersant. The polyisobutenyl succinimide dispersant typically contains boron in an amount of 0.1 wt.% to 2 wt.% and nitrogen in an amount of 0.5 wt.% to 5 wt.% based on the total weight of the polyisobutenyl succinimide dispersant. According to an exemplary embodiment, the boron-containing polyisobutenyl succinimide dispersant has an average molecular weight of 1300, a nitrogen content of 1.95 wt.%, and a boron content of 0.63 wt.%. The boron-containing polyisobutenyl succinimide dispersant is typically present in an amount of 0.3 wt.% to 2.0 wt.%, based on the total weight of the lubricating oil composition. In one embodiment, the polyisobutenyl succinimide provides a nitrogen content of 156 ppm and a boron content of 60 ppm to the lubricating oil composition. The boric acid-containing polyisobutenyl succinimide can provide good results when subjected to the Komatsu Hot Tube test. It is clean and inhibits the adhesion of high temperature deposits.

[0075] Other Additives The lubricating oil composition may further comprise at least one additive or at least one 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 composition 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, antifoam agents, metal activity reducers, dispersants, corrosion inhibitors, lubricity improvers, thermal stability improvers, anti-fog additives, anti-icing agents, dyes, markers, static dissipative agents, biocides, and combinations thereof. In general, the concentration of each of the additives in the lubricating oil composition, if used, may range from 0.001 wt%, 0.01 wt%, or 0.1 wt% to 8 wt%, 10 wt%, or 15 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 0.001 wt%, 0.01 wt%, or 0.1 wt% to 8 wt%, 10 wt%, or 20 wt%, based on the total weight of the lubricating oil composition.

[0076] The lubricating oil compositions disclosed herein may, in some embodiments, be substantially free of metals (i.e., contain less than 50 ppm of metals). The presence of polar or ionic compounds has been shown to increase the conductivity of transmission fluids (and thereby reduce the volume resistivity) in 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. In particular, metal-containing additives such as detergents should be minimized as they adversely affect the volume resistivity of the lubricating oil composition, but the presence of dispersants, friction modifiers, and antiwear agents also contribute to increasing the bulk fluid conductivity.

[0077] The optional additives described above are typically ashless (metal-free) and also have a volume resistivity of less than 1.0×10 9 A sufficiently high volume resistivity is selected to provide adequate insulating properties in the lubricating oil composition.

[0078] Optionally, the lubricating oil composition disclosed herein may further comprise a friction modifier (FM). Various friction modifiers may be used as friction modifiers contained in the lubricating oil composition disclosed herein. Examples include various oiliness improvers, such as fatty acid esters, fatty acid amides, diols, amine compounds, and molybdenum compounds. Molybdenum-based FMs are metal-based FMs, and therefore may have reduced volume resistivity. Therefore, it may be desirable to keep the metal content below 50 ppm. The friction modifiers may be used alone or in combination with multiple friction modifiers.

[0079] Optionally, the lubricating oil composition disclosed herein may further comprise an antioxidant capable of reducing or preventing oxidation of the base oil. Any antioxidant known to a person skilled in the art may be used in the lubricating oil composition. 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.), phenol-based antioxidants (e.g., 2-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2,6 -di-tert-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 phenol-based antioxidants, etc.), phosphorus-based antioxidants (e.g., phosphorous acid, etc.), zinc dithiophosphate, oil-soluble copper compounds, and combinations thereof. 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.

[0080] The lubricating oil compositions disclosed herein may optionally include a pour point depressant capable of lowering 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 polymethacrylates, alkyl acrylate polymers, alkyl methacrylate polymers, di(tetra-paraffin phenol) phthalate, condensates of tetra-paraffin phenol, condensates of chlorinated paraffins with 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. 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.

[0081] The lubricating oil composition disclosed herein may optionally include a foam inhibitor or antifoaming agent capable of dissipating foam in the oil. Any foam inhibitor or antifoaming agent known to those skilled in the art may be used in the lubricating oil composition. Non-limiting examples of suitable antifoaming agents include silicone oils or polydimethylsiloxanes, fluorosilicones, alkoxylated fatty acids, polyethers (e.g., polyethylene glycols), branched polyvinyl ethers, alkyl acrylate polymers, alkyl methacrylate polymers, polyalkoxyamines, and combinations thereof. In some embodiments, the antifoaming agent includes glycerol monostearate, polyglycol palmitate, trialkyl monothiophosphate, esters of sulfonated ricinoleic acid, benzoylacetone, methyl salicylate, glycerol monooleate, or glycerol dioleate. Some suitable antifoaming agents are described in Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London, Springer.

[0082] In some embodiments, the lubricating oil composition may include a multifunctional additive. Some non-limiting examples of suitable multifunctional additives include sulfurized oxymolybdenum dithiocarbamates, sulfurized oxymolybdenum organophosphorus dithioates, oxymolybdenum monoglycerides, oxymolybdenum diethylate amides, amine-molybdenum complex compounds, and sulfur-containing molybdenum complex compounds.

[0083] In certain embodiments, the lubricating oil composition may include 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.

[0084] In some embodiments, the lubricating oil composition may include at least a metal deactivator. Some non-limiting examples of suitable metal deactivators include disalicylidene propylene diamine, triazole derivatives, thiadiazole derivatives, and mercaptobenzimidazole.

[0085] The additives disclosed herein may be in the form of an additive concentrate having two or more additives. The additive concentrate may include 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 paraffinic oils, naphthenic oils, asphaltic 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 carboxylic acid esters (especially diester oils), and combinations thereof. In some embodiments, the diluent is a light hydrocarbon oil (both natural and synthetic). In general, the diluent oil may have a viscosity of about 13 cSt to about 35 cSt at 40°C.

[0086] In general, it is desirable for the diluent to readily solubilize the lubricant-soluble additives of the present invention and provide an oil additive concentrate that is readily soluble in the lubricant base oil stock. In addition, it is desirable for the diluent not to impart any undesirable properties, including, for example, high volatility, high viscosity, and impurities such as heteroatoms, to the lubricant base oil stock and, ultimately, to the finished lubricant.

[0087] The present disclosure further includes an oil soluble additive concentrate composition comprising from 2.0% to 90% by weight, e.g., from 10% to 50% by weight, of an inert diluent, based on the weight of the total concentrate of the oil soluble additive composition according to the present invention.

[0088] According to an exemplary embodiment, the lubricating oil composition comprises a succinimide dispersant, a friction modifier, an antioxidant, a seal swell agent, an antifoam agent, a viscosity modifier, and a diluent oil, each in an amount of 20% by weight or less, based on the total weight of the lubricating oil composition. EXAMPLES

[0089] The lubricating oil compositions of the present disclosure utilize a combination of sulfur- and phosphorus-based additives that exhibit an excellent combination of volume resistivity, detergency, thermal and oxidative stability, antiwear and corrosion resistance at high temperatures.

[0090] The following examples are provided to illustrate embodiments of the present disclosure and are not intended to limit the present disclosure to the specific embodiments described. Unless otherwise stated, 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 present disclosure. The specific details described in each example should not be construed as necessary features of the present disclosure.

[0091] For performance evaluation, lubricating oil compositions of the present invention and comparative lubricating oil compositions were prepared from the following compositions and additives: Table 1 shows each composition including the amount (wt %) of each component.

[0092] Sulfurized olefin A(1) is a commercially available sulfurized olefin (sulfurized isobutylene) containing 46.3% by weight sulfur.

[0093] Sulfurized olefin B(2) is a commercially available sulfurized olefin containing 28.8% by weight sulfur.

[0094] The sulfurized PIB (3) is a sulfurized polyisobutylene oligomer containing 20.6% by weight sulfur made by reacting highly reactive polyisobutylene (HR PIB) with sulfur as described in U.S. Pat. No. 7,414,013.

[0095] Ashless Phosphorus Additive A is an alkyl phosphonate containing 8.5% by weight phosphorus.

[0096] Ashless Phosphorus Additive B is an amine phosphate containing 6.9% by weight phosphorus.

[0097] Ashless phosphorus additive C is a dialkyl hydrogen phosphite containing 7.2 weight percent phosphorus.

[0098] Ashless phosphorus additive D is a diaryl hydrogen phosphite containing 13.3 weight percent phosphorus.

[0099] Ashless phosphorus additive E is a phosphite containing thioether alkyl groups containing 8 weight percent phosphorus and 8.4 weight percent sulfur.

[0100] The sulfur EP additive is an alkyl thiadiazole containing 34.0 wt. % sulfur.

[0101] The corrosion inhibitor is an N-alkyltolyltriazole containing 14.6% by weight nitrogen.

[0102] The dispersant is a polyisobutenyl succinimide containing 1.95% by weight nitrogen and 0.63% by weight boron.

[0103] Other additives present in the inventive and comparative compositions are small amounts of friction modifiers, antioxidants, seal swell agents, antifoam agents, non-dispersant PMA type viscosity modifiers, and less than 1.0 wt.% diluent oil. All other additives have the same composition and loading amounts.

[0104] The base oil is a mixture of API Group II base oil and API Group III base oil. The base oil mixture has a viscosity of 3.5-4.5 mm at 100°C. 2 / s and a viscosity index of 135 or greater.

[0105] Shale 4-ball abrasion test The wear performance of each lubricating oil composition was determined by a four-ball wear scar test according to ASTM D4172 under the conditions of 1800 rpm, 80°C oil temperature, and 392N 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. A smaller wear scar diameter means a better anti-wear performance of the lubricating oil composition.

[0106] Komatsu Hot Tube (KFT) Test The Komatsu Hot Tube test is a lubricant industry bench test used to measure the detergency and thermal and oxidative stability of lubricant compositions according to JASO M355-2021 test method JPI-5S-55-99 Hot Surface Deposit Control. Detergency and thermal and oxidative stability are performance areas commonly accepted in the industry as essential for adequate overall performance of a lubricant. During the test, a specific amount of the test lubricant composition was pumped upward through a glass tube placed inside an oven set at a specific temperature. Air was introduced into the oil stream before the oil entered the glass tube and flowed upward with the oil. Evaluation of the lubricant compositions was performed at 250°C. The test temperature was set at 250°C because the thermal durability of protective coatings of polyimide ester or polyamide-based enamel on wires used in hybrid and electric vehicles is between 200 and 240°C. Evaluations were performed with the temperature further increased to 270°C to show the difference between certain formulations containing various amounts of dispersant. These results are shown in Table 2. The test results were determined by comparing the amount of lacquer deposited on the glass test tube to a rating scale ranging from 0.0 (very dark) to 10.0 (completely clean). Results are reported in multiples of 0.5. If the glass tube is completely blocked with deposit, the test result is reported as "Blocked." Blockage is indicated by a deposit below a result of 0.0, where the lacquer is very thick and dark in color, but there is still fluid flow, but at a rate that is completely insufficient for usable oil.

[0107] Indiana Stirring Oxidation Test (ISOT) Sulfur compounds are known to decompose at high temperatures and form acidic species that are responsible for increasing copper corrosion. The Indiana Stirring Oxidation Test was used to determine the high temperature oxidation stability of the lubricating oil compositions. The test was performed according to standard 5.16 Oxidation Stability Test of JASO M315-2015, but the temperature was increased to 165.5°C to make the test more severe (the standard test oil temperature specified in JASO M315-2015 is 150°C). Two catalyst plates (copper and steel) and a glass varnish rod were immersed in the test oil, and the test oil was heated and aerated by stirring at 165.5°C for 96 hours. At the end of the heating period, the copper content of the test oil was measured by ICP. A lower copper (Cu) content means less corrosiveness and therefore a higher oxidation stability of the sulfur compounds. Conversely, a higher Cu content means an increased formation of acidic species resulting from the decomposition of the sulfur additive under these conditions. The copper content is reported in Table 1 in parts per million (ppm).

[0108] Volume resistivity The electrical insulating capability of the lubricating oil compositions was determined by volume resistivity testing according to test method JIS C2101-1999-24. The volume resistivity of the lubricating oil compositions was measured for the freshly formulated lubricating oil compositions (denoted as "freshly formulated oil") and then for each composition 96 hours after the ISOT test (denoted as "after 96 hours"). The volume resistivities of the test lubricating oil compositions at 80°C and an applied voltage of 250 V were measured as previously described and are reported in Table 1 in units of Ω·cm. [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4]

[0109] Evaluation of the test lubricant compositions of Table 1 As shown by the results in Table 1, exemplary lubricating oil compositions 1-9 of the present invention exhibit an excellent combination of volume resistivity, detergency, thermal stability, oxidative stability, anti-wear properties and corrosion resistance at high temperatures.

[0110] Comparative compositions 3-5 containing sulfurized PIB exhibit reduced corrosion compared to comparative compositions 1 and 2 containing conventional sulfurized olefins. As shown by the examples of the present invention, the addition of a corrosion inhibitor further reduces copper corrosion levels. Furthermore, as demonstrated by the examples of the present invention, the combination of thiadiazole and sulfurized PIB provides improved wear performance over comparative examples that do not contain the combination when used at levels providing a sulfur content in the range of 0.01 wt. % to 0.2 wt. %, based on the total weight of the lubricating oil composition. [Table 2-1] [Table 2-2]

[0111] Evaluation of the test lubricant compositions of Table 2 Table 2 shows results from various compositions in which the amount of borate-containing succinimide dispersant ranged from 0.0 wt% to twice the amount shown in Table 1 (1.6 wt%). As shown in Table 2, Comparative Example 6 has the same composition as Example 1, but does not contain a dispersant. The same is true for Comparative Example 7 and Example 3, and Comparative Example 8 and Example 8. As shown in the table, the comparative examples without dispersant have very poor KHT test results. Furthermore, when these compositions are tested according to ISOT (JASO M315-15, ATF 5.16: Thermal & Oxidation Stability Test, oil temperature 165.5°C, 96 hours), sludge is produced. In contrast, the compositions of the present invention containing borate-containing dispersants do not produce lacquer (sludge).

[0112] Examples 10 and 11 contain twice the amount of dispersant compared to Examples 3 and 8, respectively. As shown in Table 2, the KHT results are better for the compositions with more dispersant, especially at higher temperatures.

[0113] These results are believed to demonstrate that if the lubricating oil deteriorates during use due to oxidative use, sludge may form inside the coils of enameled wire in the electromagnets inside the motor and transmission, which may result in failure. In particular, the increase in TAN and the increase in kinematic viscosity at 40°C (ISOT evaluation parameters) of test oils Examples 1 to 11 shown in Tables 1 and 2 were all less than 2.0 mg KOH / g and less than 5%, respectively, further demonstrating good levels of oxidative and thermal stability.

[0114] Additional explanation The following non-limiting clauses are provided as additional explanations of various exemplary embodiments of the present invention.

[0115] Embodiment 1. A lubricating oil composition for use in a motor vehicle equipped with an electric motor and / or generator, comprising: a. a viscosity modulus of about 1.5 mm at 100° C. 2 / s~approx.20mm 2 a. a major amount of an oil of lubricating viscosity having a kinematic viscosity in the range of 100 / s; and b. a sulfur-based additive comprising a thiadiazole and a sulfurized polyolefin of formula (I), [ka] wherein R1 is hydrogen or methyl, and R2 is a C8 to C40 hydrocarbyl group, and the sulfur-based additive provides sulfur to the lubricating oil composition in an amount of 0.01 wt % to 0.2 wt %, based on the total weight of the lubricating oil composition; c. a phosphorus compound; and d. a boron-containing ashless polyisobutenyl succinimide-based dispersant.

[0116] Embodiment 2. The lubricating oil composition of embodiment 1, wherein the sulfurized polyolefin of formula (I) provides the lubricating oil composition with a sulfur content of 0.01 wt. % to 0.2 wt. %, based on the total weight of the lubricating oil composition.

[0117] Embodiment 3. The lubricating oil composition of any of the preceding embodiments, wherein the thiadiazole provides the lubricating oil composition with a sulfur content of 0.005 wt.% to 0.2 wt.%, based on the total weight of the lubricating oil composition.

[0118] Embodiment 4. The lubricating oil composition of any of the preceding embodiments, comprising a total amount of sulfur from 0.01 wt. % to 0.2 wt. %, based on the total weight of the lubricating oil composition.

[0119] Embodiment 5. The lubricating oil composition contains less than 50 ppm metals and has a pH of 1.0×10 at 80° C. 9 The lubricating oil composition of any of the preceding embodiments, having a volume resistivity greater than Ω·cm.

[0120] Embodiment 6. The lubricating oil composition of any of the preceding embodiments, wherein the phosphorus compound comprises at least one of phosphoric acid, phosphoric acid esters, amine salts of phosphoric acid esters, phosphonic acid, phosphonic acid esters, phosphorous acid, and phosphite esters.

[0121] Embodiment 7. The lubricating oil composition of any of the preceding embodiments, comprising phosphorus in a total amount of 0.005 wt.% to 0.2 wt.%, based on the total weight of the lubricating oil composition.

[0122] Embodiment 8. The lubricating oil composition of any of the preceding embodiments, wherein the ashless polyisobutenyl succinimide dispersant contains boron in an amount from 0.003% to 0.02% by weight, based on the total weight of the ashless polyisobutenyl succinimide dispersant.

[0123] Embodiment 9. The lubricating oil composition of any of the preceding embodiments, comprising a nitrogen-containing corrosion inhibitor.

[0124] Embodiment 10. The lubricating oil composition of any of the preceding embodiments, wherein the oil of lubricating viscosity comprises a Group II base stock and a Group III base stock.

[0125] Embodiment 11. The sulfurized polyolefin of Formula I is a sulfurized polyisobutylene oligomer of Formula II, [ka] wherein R1 is hydrogen or methyl, m is an integer from 1 to 9, and n is 0 or 1.

[0126] Embodiment 12. A method of reducing corrosion and improving wear protection in a transmission system of a motor vehicle having an electric motor and / or generator by lubricating the transmission system with a lubricating oil composition, the lubricating oil composition having a. a viscosity of about 1.5 mm at 100° C. 2 / s~approx.20mm 2 a. a major amount of an oil of lubricating viscosity having a kinematic viscosity in the range of 100 / s; and b. a sulfur-based additive comprising a thiadiazole and a sulfurized polyolefin of formula (I), [ka] wherein R1 is hydrogen or methyl and R2 is a C8 to C40 hydrocarbyl group, and the sulfur-based additive provides sulfur to the lubricating oil composition in an amount of 0.01 wt % to 0.2 wt %, based on the total weight of the lubricating oil composition; c. a phosphorus compound; and d. a boron-containing ashless polyisobutenyl succinimide-based dispersant.

[0127] Embodiment 13. The method of embodiment 11, wherein the sulfur-based additive consists of the thiadiazole and the sulfurized polyolefin of formula (I).

[0128] Embodiment 14. The method of any preceding embodiment, wherein the sulfurized polyolefin of Formula (I) provides the lubricating oil composition with a sulfur content of 0.01 wt.% to 0.2 wt.%, based on the total weight of the lubricating oil composition.

[0129] Embodiment 15. The method of any preceding embodiment, wherein the thiadiazole provides the lubricating oil composition with a sulfur content of 0.005 wt.% to 0.2 wt.%, based on the total weight of the lubricating oil composition.

[0130] Embodiment 16. The method of any of the preceding embodiments, wherein the lubricating oil composition comprises sulfur in a total amount of 0.01 wt.% to 0.2 wt.%, based on the total weight of the lubricating oil composition.

[0131] Embodiment 17. The lubricating oil composition contains less than 50 ppm metals and has a 1.0×10 9 4. The method of any preceding embodiment, having a volume resistivity of greater than Ω·cm.

[0132] Embodiment 18. The method of any of the preceding embodiments, wherein the phosphorus compound comprises at least one of phosphoric acid, a phosphoric acid ester, an amine salt of a phosphoric acid ester, a phosphonic acid, a phosphonic acid ester, phosphorous acid, and a phosphite ester.

[0133] Embodiment 19. The method of any preceding embodiment, wherein the lubricating oil composition comprises phosphorus in a total amount of 0.005 wt.% to 0.2 wt.%, based on the total weight of the lubricating oil composition.

[0134] Embodiment 20. The method of any preceding embodiment, wherein the ashless polyisobutenyl succinimide dispersant contains boron in an amount of 0.003% to 0.02% by weight, based on the total weight of the ashless polyisobutenyl succinimide dispersant.

[0135] Embodiment 21. The method of any of the preceding embodiments, wherein the lubricating oil composition comprises a nitrogen-containing corrosion inhibitor and the oil of lubricating viscosity comprises a Group II base stock and a Group III base stock.

[0136] It will be understood that various modifications may be made to the embodiments disclosed herein. Thus, the above description should not be construed as limiting, but merely as an illustration of exemplary 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 appended claims.

Claims

1. 1. A lubricating oil composition for a motor vehicle equipped with an electric motor and / or generator, comprising: a. At 100°C, approximately 1.5 mm ２ / s ~ approx. 20mm ２ a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of 1 / 2 s; b. A sulfur-based additive comprising a thiadiazole and a sulfurized polyolefin of formula (I), 【Chemical 1】 In the formula, R １ is hydrogen or methyl, and R ２ is a C8 to C40 hydrocarbyl group, and the sulfur-based additive provides sulfur to the lubricating oil composition in an amount of 0.01 wt % to 0.2 wt %, based on the total weight of the lubricating oil composition; c. a phosphorus compound; and d) a boron-containing ashless polyisobutenyl succinimide dispersant.

2. 10. The lubricating oil composition of claim 1, comprising a triazole-containing corrosion inhibitor.

3. 10. The lubricating oil composition of claim 1, wherein the oil of lubricating viscosity comprises a Group II base stock and a Group III base stock.

4. The sulfurized polyolefin of Formula I is a sulfurized polyisobutylene oligomer of Formula II: 【Chemistry 2】 2. The lubricating oil composition of claim 1, wherein R1 is hydrogen or methyl, m is an integer from 1 to 9, and n is 0 or 1.

5. 1. A method of reducing corrosion and improving wear protection in a transmission system of a motor vehicle having an electric motor and / or generator by lubricating the transmission system with a lubricating oil composition comprising: a. At 100°C, approximately 1.5 mm ２ / s ~ approx. 20mm ２ a major amount of oil of lubricating viscosity having a kinematic viscosity in the range of 1 / 2 s; b. A sulfur-based additive comprising a thiadiazole and a sulfurized polyolefin of formula (I), 【Chemistry 3】 wherein R1 is hydrogen or methyl and R2 is a C8 to C40 hydrocarbyl group, and the sulfur-based additive provides sulfur to the lubricating oil composition in an amount of 0.01 wt % to 0.2 wt %, based on the total weight of the lubricating oil composition; c. a phosphorus compound; and d. a boron-containing ashless polyisobutenyl succinimide dispersant.

6. 6. The method of claim 5, wherein said sulfur-based additive consists of said thiadiazole and said sulfurized polyolefin of formula (I).

7. 6. The method of claim 5 or the lubricating oil composition of claim 1, wherein the sulfurized polyolefin of Formula (I) provides the lubricating oil composition with a sulfur content of 0.01 wt. % to 0.2 wt. %, based on the total weight of the lubricating oil composition.

8. 6. The method of claim 5 or the lubricating oil composition of claim 1, wherein the thiadiazole provides the lubricating oil composition with a sulfur content of 0.005 wt % to 0.2 wt %, based on the total weight of the lubricating oil composition.

9. 6. The method of claim 5 or the lubricating oil composition of claim 1, wherein the lubricating oil composition comprises sulfur in a total amount of from 0.01 wt % to 0.2 wt %, based on the total weight of the lubricating oil composition.

10. The lubricating oil composition contains less than 50 ppm of metals and has a 1.0 x 10 ９ 6. The method of claim 5 or the lubricating oil composition of claim 1, having a volume resistivity of greater than ohm-cm.

11. 6. The method of claim 5 or the lubricating oil composition of claim 1, wherein the phosphorus compound comprises at least one of phosphoric acid, phosphoric acid esters, amine salts of phosphoric acid esters, phosphonic acid, phosphonic acid esters, phosphorous acid, and phosphite esters.

12. 6. The method of claim 5 or the lubricating oil composition of claim 1, wherein the lubricating oil composition comprises phosphorus in a total amount of from 0.005 wt % to 0.2 wt %, based on the total weight of the lubricating oil composition.

13. 6. The method of claim 5 or the lubricating oil composition of claim 1, wherein the ashless polyisobutenyl succinimide dispersant comprises boron in an amount from 0.003 wt % to 0.02 wt %, and nitrogen in an amount from 0.005 wt % to 0.10 wt %, based on the total weight of the ashless polyisobutenyl succinimide dispersant.

14. 6. The method of claim 5, wherein the lubricating oil composition comprises a nitrogen-containing corrosion inhibitor and the oil of lubricating viscosity comprises a Group II base stock and a Group III base stock.

15. 6. The method of claim 5, wherein the lubricating oil composition comprises a corrosion inhibitor comprising a tolyltriazole derivative, for example, a tolyltriazole derivative having an alkylamine moiety, and the oil of lubricating viscosity comprises a Group II base stock and a Group III base stock.

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