Durable lubricating fluid for electric vehicles

Abstract

The present disclosure relates to a durable lubricating fluid for an electric motor or a hybrid electric motor. The disclosed technology relates to a durable lubricating fluid comprising an oil of lubricating viscosity, a thiadiazole or a derivative thereof, and an amine salt of phosphoric acid.

Description

Technical Field

[0001] This disclosure relates to a durable lubricating fluid for an electric motor or hybrid electric motor. The disclosed technology relates to a durable lubricating fluid comprising an oil of lubricating viscosity, a thiadiazole or derivative thereof, and an amine salt of a phosphate ester, and having a sulfur plus phosphorus to nitrogen ((S+P) / N) weight ratio of at least 2.3. This lubricant exhibits a durable electrical conductivity of 50,000 pS / m. Background Art

[0002] A major challenge in developing electric or hybrid electric motors is developing a lubricant that maintains a relatively low electrical conductivity even after aging. These types of lubricants should maintain a relatively low electrical conductivity (or conversely, a relatively high resistivity) over the service life of the lubricant to inhibit the accumulation and discharge of static electricity in the live components of the electric or hybrid electric motor.

[0003] Lubricating fluids used in conventional internal combustion engines typically employ additives to provide sufficient amounts of sulfur and phosphorus to impart wear and extreme pressure protection to the mechanical components. However, such additives in lubricating fluids used in electric or hybrid electric motors can be problematic because reactive sulfur and phosphorus compounds are chemically aggressive to the copper wire and copper-based alloys used in electric or hybrid electric motors. Additionally, sulfur and phosphorus compounds are generally electrically conductive, and including reactive sulfur and phosphorus compounds in a lubricant can result in an undesirable increase in the conductivity of the lubricant. Lubricating fluids used in electric and hybrid electric motors therefore have the additional challenge of maintaining a relatively low electrical conductivity while still protecting the copper components and providing adequate protection to the mechanical components.

[0004] Summary of the invention and terminology

[0005] In one aspect or embodiment, a durable lubricating composition for an electric or hybrid electric vehicle is described herein. In an embodiment, the lubricating composition includes a base oil of lubricating viscosity; at least about 0.7 weight percent of a thiadiazole or a derivative thereof; an amine salt of a phosphate ester that provides at least about 100 ppm of phosphorus to the durable lubricating composition; a weight ratio of sulfur plus phosphorus to nitrogen ((S+P) / N) of at least 2.3; the lubricating composition having at least about 150 ppm of phosphorus and at least about 2000 ppm of sulfur; and a conductivity durability of about 50,000 pS / m or less. The conductivity durability is defined as the difference between an initial conductivity and a final conductivity, wherein the initial and final conductivities are measured at 1.5 volts, 20 hertz, and at 160 degrees Celsius according to ATSM D2624-15, and wherein the final conductivity is measured after the lubricating composition has been aged at 170°C according to CEC L-48-A-00 for 192 hours.

[0006] In other aspects or embodiments, the thiadiazole of the durable lubricating composition can be selected from a mono-hydrocarbyl mercaptan-substituted thiadiazole, a di-hydrocarbyl mercaptan-substituted thiadiazole, or a combination thereof; and / or wherein the thiadiazole is 1,3,4-thiadiazole or a derivative thereof; and / or wherein the thiadiazole provides at least about 2000 ppm of sulfur to the durable lubricating composition; and / or wherein the lubricating composition comprises from about greater than 0.5 wt % to about 1 wt % of the thiadiazole or derivative thereof; and / or wherein the thiadiazole or derivative thereof comprises one or more compounds having the structure of Formula I:

[0007] (Formula I) wherein each R1 is independently hydrogen or sulfur; each R2 is independently an alkyl group; n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moieties is 0, and if R1 is sulfur, the integer n of the adjacent R2 moieties is 1; and wherein at least one R1 is sulfur; and / or wherein the thiadiazole or derivative thereof provides at least about 99 weight percent sulfur to the heavy-duty lubricating composition.

[0008] In other aspects or embodiments, the heavy-duty lubricating composition of any embodiment herein may include up to about 3500 ppm total sulfur and up to about 300 ppm total phosphorus.

[0009] In another aspect or embodiment, the phosphate amine salt of any embodiment herein comprises one or more of a monoalkyl phosphate and / or a dialkyl phosphate, and wherein the alkyl group thereof may be linear or branched; and / or wherein the phosphate amine salt is represented by formula II

[0010] (Formula II) wherein R3 and R4 may independently be hydrogen or a linear, branched or cyclic hydrocarbon group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R5, R6, R7 and R8 may independently be hydrogen or a hydrocarbon group and at least one of R5 to R8 is a hydrocarbon group; and / or wherein R3 and R4 may independently be a C3 to C10 alkyl group; and / or wherein R3 and R4 are C6 alkyl groups; and / or wherein at least one of R5, R6, R7 and R8 is a C6 alkyl group. wherein two of R5, R6, R7 and R8 are independently C10 to C20 alkyl groups; and / or wherein two of R5, R6, R7 and R8 are independently C12 to C14 alkyl groups; and / or wherein the amine salt of the phosphate ester provides about 40 to about 90 weight percent of the total phosphorus in the heavy-duty lubricating composition; and / or wherein the lubricating composition comprises about 0.25 to about 0.5 weight percent of the amine salt of the phosphate ester.

[0011] In other aspects or embodiments, the durable lubricating composition of any embodiment can have an initial conductivity of about 150,000 pS / m or less, or less, when measured at 160°C according to ASTM D2624-15.

[0012] In other aspects or embodiments, the present disclosure provides for use of a durable lubricating composition (or method of lubricating) in an electric or hybrid electric motor, wherein the durable lubricating composition comprises a base oil of lubricating viscosity; at least about 0.7 weight percent of a thiadiazole or a derivative thereof; an amine salt of a phosphate ester providing at least about 100 ppm of phosphorus to the durable lubricating composition; a weight ratio of sulfur plus phosphorus to nitrogen ((S+P) / N) of at least 2.3; the lubricating composition having at least about 150 ppm phosphorus and at least about 2000 ppm sulfur, and a conductivity durability of about 50,000 pS / m or less. The conductivity durability is defined as the difference between initial and final conductivity, wherein the initial and final conductivities are measured at 1.5 volts, 20 hertz, and 160 degrees Celsius according to ATSM D2624-15, and wherein the final conductivity is measured after the lubricating composition has been aged at 170° C. for 192 hours according to CEC L-48-A-00. The uses or methods herein may also include any of the optional features of any of the embodiments described in this Summary.

[0013] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.The following definitions of terms are provided to clarify the meaning of certain terms as used herein.

[0014] The terms "lubricating oil," "lubricant composition," "lubricating composition," "lubricant," and "lubricating and cooling fluid" refer to a finished lubricating product comprising a major amount of base oil and a minor amount of an additive composition.

[0015] As used herein, the terms "additive package," "additive concentrate," "additive composition," and "transmission fluid additive package" refer to that portion of a lubricating oil composition that excludes a major amount of base oil.

[0016] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from hydrocarbyl substituents and substituted hydrocarbyl substituents containing one or more of the following: halo, hydroxy, alkoxy, mercapto, nitro, nitroso, amino, pyridyl, furyl, imidazolyl, oxygen, and nitrogen, and wherein no more than two non-hydrocarbyl substituents are present for every ten carbon atoms in the hydrocarbyl group.

[0017] Unless expressly stated otherwise, as used herein, the term "weight percent" or "wt%" refers to the percentage of the component by weight of the entire composition.

[0018] As used herein, the terms "soluble," "oil-soluble," or "dispersible" may mean, but do not necessarily mean, that a compound or additive is soluble, dissolvable, miscible, or capable of being suspended in oil in all proportions. However, the above terms do mean that they are, for example, soluble, suspendable, dissolvable, or stably dispersible in the oil to an extent sufficient to exert their intended effect in the environment in which the oil is used. Furthermore, the addition of other additives may also allow for the incorporation of higher levels of a particular additive, if desired.

[0019] As used herein, the term "alkyl" refers to a straight chain, branched chain, cyclic and / or substituted saturated chain moiety of about 1 to about 200 carbon atoms.

[0020] As used herein, the term "alkenyl" refers to a straight, branched, cyclic and / or substituted unsaturated chain moiety of about 3 to about 30 carbon atoms.

[0021] As used herein, the term "aryl" refers to monocyclic and polycyclic aromatic compounds that may include alkyl, alkenyl, alkaryl, amino, hydroxy, alkoxy, halide substituents and / or heteroatoms including, but not limited to, nitrogen and oxygen.

[0022] As used herein, "number average molecular weight" or "Mn" is determined by gel permeation chromatography (GPC) using commercially available polystyrene standards with Mn ranging from 180 to about 18,000 as a calibration reference. The GPC method additionally provides molecular weight distribution information; see, for example, W. W. Yau, J. J. Kirkland, and D. D. Bly, Modern Size Exclusion Liquid Chromatography, John Wiley & Sons, New York, 1979, which is also incorporated herein by reference.

[0023] It should be understood that throughout this disclosure, the terms "comprising," "including," "containing," and the like are to be construed as open ended and include any elements, steps, or ingredients not expressly listed. The term "consisting essentially of" is intended to include any expressly listed elements, steps, or ingredients, as well as any additional elements, steps, or ingredients that do not materially affect the basic and novel aspects of the invention. This disclosure also contemplates that any composition described using the terms "comprising," "including," or "containing" should also be construed to include disclosure of the same composition as "consisting essentially of" or "consisting of" the specifically listed components. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a graph of conductivity durability versus sulfur, phosphorus, and nitrogen levels. DETAILED DESCRIPTION

[0025] Disclosed herein is a durable lubricating fluid suitable for use in electric or hybrid electric vehicles. The durable lubricating fluid contains sulfur and phosphorus to provide wear protection, but is delivered in a manner that unexpectedly maintains a relatively low electrical conductivity as the lubricant ages.

[0026] In one aspect or embodiment, the durable lubricating fluid herein comprises a base oil of lubricating viscosity; at least about 0.7% by weight of a thiadiazole or derivative thereof, which provides sulfur and nitrogen to the fluid; and an amine salt of a phosphate ester, which provides phosphorus and nitrogen to the fluid. The fluid also has a sulfur plus phosphorus to nitrogen ((S+P) / N) weight ratio of at least 2.3 and has at least about 150 ppm phosphorus and at least about 2000 ppm sulfur. When the fluid includes at least these additives and the ratios between the provided sulfur, phosphorus, and nitrogen, the fluid exhibits a conductivity durability of about 50,000 pS / m or less (as described in more detail herein). In other aspects or embodiments, the fluid herein further contains other sources of phosphorus, nitrogen, and / or sulfur, as long as the fluid includes the thiadiazole or derivative thereof and the amine salt of phosphate additive and the sulfur, phosphorus, and nitrogen ratios specified above.

[0027] In other methods, the phosphorus content of the fluid may be up to 300 ppm, up to 290 ppm, up to 270 ppm, up to 260 ppm, up to 250 ppm, up to 240 ppm, up to 230 ppm, up to 220 ppm, up to 200 ppm, up to 190, or up to 180. The fluid may also include at least 150 ppm total phosphorus, or between 150 ppm and 300 ppm phosphorus, or between 180 and 300 ppm phosphorus, or any range therebetween. At least a portion of the phosphorus is provided by the amine phosphate additive described herein.

[0028] In other methods, the sulfur content of the fluid can be up to 5000 ppm, up to 4500 ppm, up to 4000 ppm, up to 3500 ppm, up to 3000 ppm, or up to 2600 ppm. The fluid can also include at least about 2000 ppm of sulfur or about 2000 ppm to 5000 ppm of sulfur, or any range therebetween. At least a portion of the sulfur, and in some methods, a majority of the sulfur, is provided by a thiadiazole or derivative thereof as described herein. In some methods, a thiadiazole or derivative thereof as described herein can provide at least about 98% of the total sulfur to the fluid.

[0029] As discussed further below, embodiments of the fluids herein having a base oil and at least a thiadiazole or derivative thereof, and an amine salt of a phosphate ester additive typically have a kinematic viscosity of 4.5 cSt to 6.0 cSt at 100° C. and exhibit an initial conductivity of about 150,000 pS / m or less as measured in accordance with ASTM D2624-15 (e.g., at 1.5 volts, 20 Hz, and at 160° C. using an Epsilon+ conductivity meter available from Flucon FluidControl GmbH or equivalent), and a conductivity durability of less than about 50,000 pS / m (absolute values ​​and discussed in more detail below) after the fluid has been aged for 192 hours in accordance with CEC L-48-A-00 170C. In the context of fluids for electric motors or hybrid electric motors, fluids having relatively low conductivity (i.e., higher resistivity) and those with minimal conductivity change upon aging are desirable.

[0030] Base oil:

[0031] Base oils or base oils of lubricating viscosity suitable for formulating durable lubricating fluids for electric and hybrid electric motor vehicles according to the present disclosure may be selected from any one of suitable synthetic or natural oils or mixtures thereof having a suitable lubricating viscosity. Natural oils may include animal and vegetable oils (e.g., castor oil, lard) and mineral oils, such as liquid petroleum oils and solvent-treated or acid-treated paraffinic, naphthenic, or mixed paraffinic-naphthenic mineral lubricating oils.

[0032] Oils derived from coal or shale may also be suitable. In addition, oils derived from the Fischer-Tropsch gas-to-liquids process are also suitable. Fischer-Tropsch synthesized hydrocarbons are produced from synthesis gas containing H2 and CO using a Fischer-Tropsch catalyst. Such hydrocarbons typically require further processing to be used as base oils. These types of oils are commonly referred to as gas-to-liquids (GTL). The base oil may have a kinematic viscosity of 2 to 15 cSt at 100°C, as measured according to ASTM D2270-10 (2016).

[0033] The base oil used in the fluids described herein can be a single base oil or a mixture of two or more base oils. The one or more base oils can be selected from any base oil in Groups II to V as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guide. These base oils are shown in Table 1 below:

[0034] Table 1: Base oils

[0035]

[0036] In one variation, in any of the embodiments herein, the base oil may be selected from Group II to Group V base oils or mixtures thereof. In one embodiment, the base oil comprises a Group III base oil or a blend of a Group III base oil with a Group II, Group IV, and / or Group V base oil.

[0037] API Group III base oils may include oils derived from Fischer-Tropsch hydrocarbons. Fischer-Tropsch hydrocarbons are made from synthesis gas containing H2 and CO using a Fischer-Tropsch catalyst. Such hydrocarbons typically require further processing to be used as base oils. These types of oils are commonly referred to as gas-to-liquids (GTLs). For example, hydrocarbons may be hydroisomerized using the processes disclosed in U.S. Patent Nos. 6,103,099 or 6,180,575; hydrocracked and hydroisomerized using the processes disclosed in U.S. Patent Nos. 4,943,672 or 6,096,940; dewaxed using the processes disclosed in U.S. Patent No. 5,882,505; or hydroisomerized and dewaxed using the processes disclosed in U.S. Patent Nos. 6,013,171, 6,080,301, or 6,165,949.

[0038] API Group IV base oils, PAOs, are typically derived from monomers having 4 to 30, or 4 to 20, or 6 to 16 carbon atoms. Examples of PAOs useful in the present invention include those derived from octene, decene, mixtures thereof, and the like. The PAOs may have a kinematic viscosity at 100°C of 2 to 15, or 3 to 12, or 4 to 8 cSt, as measured according to ASTM D2270-10. Examples of PAOs include a 4 cSt PAO at 100°C, a 6 cSt PAO at 100°C, and mixtures thereof.

[0039] Group V base oils include synthetic and natural ester base fluids. Synthetic esters can include esters of dicarboxylic acids and monohydric alcohols. Specific 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, behenyl sebacate, and the 2-ethylhexyl diester of linoleic acid dimer. Other synthetic esters include C5 to C 12 Those made from monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol, etc. The esters may also be monoesters of monocarboxylic acids and monohydric alcohols.

[0040] Natural esters refer to substances derived from renewable biological resources, organisms or entities, as opposed to substances derived from petroleum or equivalent raw materials. Natural esters include fatty acid triglycerides, hydrolyzed or partially hydrolyzed triglycerides, or transesterified triglycerides, such as fatty acid methyl esters (or FAMEs). Suitable triglycerides include, but are not limited to, palm oil, soybean oil, sunflower oil, rapeseed oil, olive oil, linseed oil, and related substances.

[0041] The base oil can be combined with selected sulfur and phosphorus additives as disclosed in the embodiments herein, along with other optional additives, to provide a lubricating fluid for use in an electric motor vehicle. Thus, the base oil can be present in the lubricating fluid in an amount greater than about 80 wt % or about 90 wt % or greater, based on the total weight of the lubricating fluid. In some embodiments, the base oil can be present in the lubricating fluid in an amount greater than about 95 wt % based on the total weight of the lubricating fluid.

[0042] Thiadiazole additives :

[0043] The durable lubricating compositions herein include a thiadiazole or a derivative thereof in an amount of about 0.7 wt % or greater. In some methods, about 0.7 wt % to about 1 wt %, or about 0.7 wt % to about 0.9 wt % of the thiadiazole or a derivative thereof is present in the durable lubricating composition. In some embodiments, the thiadiazole or a derivative thereof is a mixture of thiadiazole compounds and / or hydrocarbyl-substituted derivatives thereof.

[0044] In some methods, the thiadiazole or its derivative provides at least about 2000 ppm of sulfur to the heavy-duty lubricating composition, in other methods, at least about 2200 ppm of sulfur, at least about 2400 ppm of sulfur, at least about 2600 ppm of sulfur, at least about 2800 ppm of sulfur, or at least about 2900 ppm of sulfur. In other methods, the thiadiazole or its derivative provides about 3500 ppm of sulfur or less, and in other methods, about 3150 ppm of sulfur or less to the heavy-duty lubricating composition.

[0045] Surprisingly, the form and amount of thiadiazole or its derivative contributes to the conductivity durability of the lubricating composition while also providing sulfur to provide wear performance characteristics. In terms of method, the thiadiazole or its derivative includes one or more compounds having the structure of Formula I:

[0046]

[0047] wherein each R1 is independently hydrogen or sulfur, each R2 is independently alkyl, n is an integer of 0 or 1, and if R1 is hydrogen, the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, the integer n of the adjacent R2 moiety is 1, with the proviso that at least one R1 is sulfur. In other methods, the thiadiazole additive is a blend of compounds of Formula Ia and Formula Ib as shown below:

[0048]

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

[0050]

[0051] wherein in Formula Ib, one integer n is 1, the associated R2 group is a C5 to C15 alkyl group (preferably a C8 to C12 alkyl group), and the associated R1 group is sulfur, and another integer n is 0, the associated R1 group is hydrogen. In some embodiments, the thiadiazole or derivative thereof comprises a blend of Formulas Ia and Ib, wherein Formula Ia is the majority of the blend, and in other approaches, the blend of Ia and Ib is about 75 to about 90 weight percent Ia and about 10 to about 25 weight percent Ib (or other ranges therebetween). In another approach, the thiadiazole is a 2,5-dithiothio-1,3,4-thiadiazole, comprising 2,5-bis-(nonyldisulfide)-1,3,4-thiadiazole (e.g., about 75% to about 90%) and 2,5-mono-(nonyldisulfide)-1,3,4-thiadiazole (e.g., about 10% to about 25%). In other methods or embodiments, examples of thiadiazole compounds that can be used in the fluids herein include 2-mercapto-5-alkylthio-1,3,4-thiadiazole; 2-mercapto-5-alkyldithio-1,3,4-thiadiazole; 2,5-bis(alkylthio)-1,3,4-thiadiazole; 2,5-bis(alkyldithio)-1,3,4-thiadiazole, variants thereof, or combinations thereof. 1,3,4-thiadiazole is typically synthesized from hydrazine and carbon disulfide by known methods. See, for example, U.S. Patent Nos. 2,765,289; 2,749,311; 2,760,933; 2,850,453; 2,910,439; 3,663,561; 3,862,798; and 3,840,549.

[0052] In other approaches, thiadiazoles or derivatives thereof can also provide a majority of the sulfur in the durable lubricating compositions herein. In some approaches, selected thiadiazoles or derivatives herein can provide at least about 98 wt% of the total sulfur or at least about 99 wt% of the total sulfur in the lubricating composition. As discussed further below, the compositions herein also have a selected relationship of sulfur and phosphorus relative to nitrogen to achieve robust conductivity durability performance.

[0053] In methods or embodiments, the fluids herein include at least about 0.7 weight percent, at least about 0.8 weight percent, or at least about 0.85 weight percent thiadiazole or a derivative thereof, and in some embodiments, less than about 1 weight percent, less than about 0.95 weight percent, or less than about 0.9 weight percent thiadiazole or a derivative thereof.

[0054] Phosphorus additives:

[0055] The durable lubricating composition herein also includes a phosphorus additive in an amount of about 0.25 wt % to about 0.5 wt %. In a method or embodiment, the selected phosphorus additive is an amine salt of a phosphate ester in an amount that provides at least about 100 ppm of phosphorus to the durable lubricating composition (in other methods, about 130 ppm of phosphorus to about 160 ppm of phosphorus is provided to the lubricating composition herein). The amine salt of the phosphate ester may include one or more monoalkyl phosphates, dialkyl phosphates, and / or mixtures thereof, wherein the alkyl groups thereof may be linear, branched, or cyclic. The fluid herein may also include other compounds that provide phosphorus, but in some embodiments, the amine salt of the phosphate ester herein provides about 40 to about 90 wt % of the total phosphorus in the durable lubricating composition (in other embodiments, about 50 to about 80 wt % of the phosphorus in the lubricating composition herein, or about 50 to about 70 wt % of the phosphorus).

[0056] In a method or embodiment, the amine salt of a phosphate ester may be represented by Formula II

[0057]

[0058] Wherein R3 and R4 can independently be hydrogen or straight chain, branched or cyclic hydrocarbon group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R5, R6, R7 and R8 can independently be hydrogen or hydrocarbon group and at least one of R5 to R8 is hydrocarbon group. Examples of suitable alkyl or hydrocarbon groups for R3 and / or R4 include straight chain or branched alkyl groups, such as but not limited to propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and / or decyl. In a further exemplary method, R3 and R4 can be cyclic hydrocarbon groups and examples include cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclopentyl, dimethylcyclopentyl, methylethylcyclopentyl, diethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, methylethylcyclohexyl, diethylcyclohexyl, methylcycloheptyl, dimethylcycloheptyl, methylethylcycloheptyl and / or diethylcycloheptyl. In some methods or embodiments, suitable phosphate amine salts are mixtures of monoalkyl and dialkyl phosphates. As described above, the monoalkyl and dialkyl groups can be linear, branched, or cyclic.

[0059] The amine salt of phosphate is known to the technician and can be derived from primary amine, secondary amine or tertiary amine, or its mixture. The exemplary amine suitable for salt can be aliphatic, cyclic, aromatic or non-aromatic, but is typically aliphatic amine. The embodiment of suitable primary amine includes ethylamine, propylamine, butylamine, 2-ethylhexylamine, bis-(2-ethylhexyl)amine, octylamine and dodecylamine, and fatty amine, such as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine or oleylamine. The embodiment of suitable secondary amine includes dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine, N-methyl-1-amino-cyclohexane and / or ethylpentylamine. Secondary amine can also be cyclic amine, such as piperidine, piperazine and morpholine. The embodiment of suitable tertiary amine can include tri-n-butylamine, tri-n-octylamine, tridecylamine, trilaurylamine, trihexadecylamine and / or dimethyloleylamine.

[0060] In some methods, the amine of Formula II above may have at least one of the R5, R6, R7, or R8 groups that is a C10 to C20 alkyl group, and in other methods or embodiments, at least two of the R5, R6, R7, or R8 groups are independently C10 to C20 alkyl groups. In some embodiments, at least two of the R5, R6, R7, or R8 groups are independently C12 to C14 alkyl groups.

[0061] Amine salts of phosphate esters can be as described in US 9,574,156, which is incorporated herein by reference, and can be prepared by reacting a suitable phosphorus compound with an amine to form an amine salt of the phosphate ester. In one embodiment, the amine salt of the phosphate ester can be of formula (II), wherein R3 and R4 can independently be C6 or hydrogen; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R5, R6, R7, and R8 can independently be hydrogen or a C12-C14 hydrocarbon group and at least one of R5 to R8 is a C12-C14 hydrocarbon group. In the method, the amine salt of the phosphate ester can be present in the durable lubricating fluid herein in an amount of at least about 0.25 weight percent, or at least about 0.3 weight percent, or up to about 0.5 weight percent, or up to about 0.35 weight percent of the lubricating composition.

[0062] Lubricant composition:

[0063] The durable lubricating composition herein comprises a base oil of lubricating viscosity, a thiadiazole or derivative thereof that provides sulfur and nitrogen to the fluid, and an amine salt of a phosphate ester that provides phosphorus and nitrogen to the fluid. The lubricating composition may include other additives as needed. Although sulfur and phosphorus can be problematic for maintaining relatively low electrical conductivity in fluids used in electric or hybrid electric motors, it has been found that if phosphorus and sulfur are provided by at least these additives and the fluid also includes a certain level of phosphorus, sulfur, and nitrogen, which is provided in a selected weight ratio of sulfur plus phosphorus to nitrogen (S+P) / N of at least about 2.3, the fluid exhibits surprisingly little change in conductivity after aging. For example, when measured according to ASTM D2624-15 at 1.5 volts, 20 hertz, and 160°C, the fluid has an initial relatively low conductivity. After the fluid is aged, the conductivity of the fluid is measured again according to the same procedure. The aging process is carried out at 170°C for 192 hours according to CEC L-48-A-00. The change in conductivity between the initial conductivity measurement and the conductivity measurement after aging is about 50,000 pS / m or less. Thus, these fluids maintain their relatively low conductivity even after aging and are considered durable lubricating compositions. In other embodiments, the selected weight ratio to achieve durability of the fluid is at least about 2.4, at least about 2.7, or at least about 2.9, and preferably less than 4.0, less than 3.5, less than 3.3, less than 3.1, or less than 3.0.

[0064] In embodiments, the fluids herein may also exhibit an initial conductivity of about 140,000 pS / m or less or about 70,000 pS / m or less, and in some methods, about 50,000 pS / m or more or about 60,000 pS / m or more. In other embodiments, the fluids also exhibit a conductivity durability (as measured as the difference between the initial conductivity and the conductivity after aging, as described above) of 50,000 pS / m or less, about 40,000 pS / m or less, about 30,000 pS / m or less, about 20,000 pS / m or less, about 10,000 pS / m or less, about 5,000 pS / m or less, or even about 2,000 pS / m or less.

[0065] Other additives: The lubricating fluids described herein may also include one or more additional additives. For example, the fluid may include at least one component selected from the group consisting of antioxidants, friction modifiers, detergents, corrosion inhibitors, copper corrosion inhibitors, defoamers, seal swell agents, extreme pressure agents, antiwear agents, viscosity modifiers, dispersants, and combinations thereof. In addition to those noted above, other performance additives may include one or more of metal passivators, demulsifiers, pour point depressants, and mixtures thereof.

[0066] Antioxidants: In some embodiments, the lubricating fluid contains one or more antioxidants. Suitable antioxidants include phenolic antioxidants, aromatic amine antioxidants, sulfur-containing antioxidants, and organic phosphites.

[0067] Examples of phenolic antioxidants include: 2,6-di-tert-butylphenol, liquid mixtures of tert-butylated phenols, 2,6-di-tert-butyl-4-methylphenol, 4,4′-methylenebis(2,6-di-tert-butylphenol), 2,2′-methylenebis(4-methyl-6-tert-butylphenol), mixed methylene-bridged polyalkylphenols, and 4,4′-thiobis(2-methyl-6-tert-butylphenol). N,N′-di-sec-butyl-phenylenediamine, 4-isopropylaminodiphenylamine, phenyl-α-naphthylamine, phenyl-α-naphthylamine, and cycloalkylated diphenylamines. Examples include hindered tert-butylphenols, bisphenols, and cinnamic acid derivatives, and combinations thereof.

[0068] Aromatic amine antioxidants include, but are not limited to, diarylamines having the formula:

[0069]

[0070] wherein R′ and R″ each independently represent a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. Examples of the substituent of the aryl group include aliphatic hydrocarbon groups such as: an alkyl group having 1 to 30 carbon atoms; a hydroxyl group; a halogen radical; a carboxylic acid or ester group; or a nitro group.

[0071] The aryl group is preferably a substituted or unsubstituted phenyl or naphthyl group, in particular, wherein one or both aryl groups are substituted by at least one alkyl group having 4 to 30 carbon atoms, preferably 4 to 18 carbon atoms, most preferably 4 to 9 carbon atoms. Preferably, one or both aryl groups are substituted, for example, monoalkylated diphenylamine, dialkylated diphenylamine, or a mixture of mono- and dialkylated diphenylamines.

[0072] Examples of diarylamines that can be used include, but are not limited to, diphenylamine; various alkylated diphenylamines; 3-hydroxydiphenylamine; N-phenyl-1,2-phenylenediamine; N-phenyl-1,4-phenylenediamine; monobutyldiphenylamine; dibutyldiphenylamine; monooctyldiphenylamine; dioctyldiphenylamine; monononyldiphenylamine; dinonyldiphenylamine; monotetradecyldiphenylamine; tetracosyldiphenylamine; phenyl-α-naphthylamine; monooctylphenyl-α-naphthylamine; phenyl-β-naphthylamine; monoheptyldiphenylamine; diheptyldiphenylamine; para-styrenated diphenylamine; mixed butyloctyldiphenylamines; and mixed octylstyryldiphenylamines.

[0073] Sulfur-containing antioxidants include, but are not limited to, sulfurized olefins, which are characterized by the type of olefin used in their production and the final sulfur content of the antioxidant. High molecular weight olefins (i.e., those having an average molecular weight of 168 to 351 g / mol) are preferred. Examples of olefins that can be used include alpha-olefins, isomerized alpha-olefins, branched olefins, cyclic olefins, and combinations thereof.

[0074] Alpha-olefins include, but are not limited to, any C4 to C25 alpha-olefin. The alpha-olefin can be isomerized prior to or during the sulfurization reaction. Structural and / or conformational isomers of alpha-olefins containing internal double bonds and / or branching can also be used. For example, isobutylene is the branched olefin counterpart of the alpha-olefin 1-butene.

[0075] Sulfur sources that can be used in the olefin sulfurization reaction include elemental sulfur, sulfur monochloride, sulfur dichloride, sodium sulfide, sodium polysulfide and mixtures thereof, which are added together or at different stages of the sulfurization process.

[0076] Unsaturated oils, due to their unsaturation, can also be sulfurized and used as antioxidants. Examples of operable oils or fats include corn oil, canola oil, cottonseed oil, grapeseed oil, olive oil, palm oil, peanut oil, coconut oil, rapeseed oil, safflower oil, sesame seed oil, soybean oil, sunflower oil, tallow, and combinations of these.

[0077] The total amount of antioxidant in the lubricating fluids described herein may be present in an amount to deliver up to 200 ppm nitrogen, or up to 175 ppm nitrogen, or between 150 and 200 ppm nitrogen.

[0078] Friction modifiers: Additional suitable friction modifiers may include metal-containing and metal-free friction modifiers and may include, but are not limited to, imidazolines, aliphatic fatty acid amides, fatty amines, succinimides, alkoxylated fatty amines, etheramines, alkoxylated etheramines, amine oxides, amidoamines, nitriles, betaines, quaternary ammonium amines, imines, amine salts, aminoguanidines, alkanolamides, phosphonates, metal-containing compounds, glycerides, sulfurized fatty compounds and olefins, sunflower oil and other naturally occurring plant or animal oils, dicarboxylic acid esters, esters or partial esters of polyols, and one or more aliphatic or aromatic carboxylic acids, and the like.

[0079] Suitable friction modifiers may contain a hydrocarbon group selected from a linear, branched or aromatic hydrocarbon group or a mixture thereof, and such hydrocarbon groups may be saturated or unsaturated. The hydrocarbon group may be composed of carbon and hydrogen or heteroatoms (such as sulfur or oxygen). The hydrocarbon group may be between 12 and 25 carbon atoms. In some embodiments, the friction modifier may be a long-chain fatty acid ester. In another embodiment, the long-chain fatty acid ester may be a monoester or a diester or a (tri)glyceride. The friction modifier may be a long-chain fatty amide, a long-chain fatty ester, a long-chain fatty epoxide derivative or a long-chain imidazoline.

[0080] Other suitable friction modifiers may include organic, ashless (metal-free), nitrogen-free friction modifiers. Such friction modifiers may include esters formed by reacting carboxylic acids and anhydrides with alkanols and generally include a polar end group (e.g., a carboxyl or hydroxyl group) covalently bonded to an oleophilic hydrocarbon chain. An example of an organic, ashless, nitrogen-free friction modifier is generally known as glyceryl monooleate (GMO), which may contain monoesters, diesters, and triesters of oleic acid. Other suitable friction modifiers are described in U.S. Patent No. 6,723,685.

[0081] Amine friction modifiers may include amines or polyamines. Such compounds may have a linear saturated or unsaturated hydrocarbon group, or a mixture thereof, and may contain from 12 to 25 carbon atoms. Other examples of suitable friction modifiers include alkoxylated amines and alkoxylated etheramines. Such compounds may have a linear, saturated or unsaturated hydrocarbon group, or a mixture thereof. They may contain from about 12 to about 25 carbon atoms. Embodiments include ethoxylated amines and ethoxylated etheramines.

[0082] The amines and amides can be used as such or as adducts or reaction products with boron compounds such as boron oxide, boron halides, metaborates, boric acid or mono-, di- or trialkylborates. Other suitable friction modifiers are described in US Pat. No. 6,300,291.

[0083] If the additional friction modifier contains nitrogen, such additional friction modifier may be present in the lubricating fluid in an amount to deliver up to 200 ppm nitrogen, or up to 150 ppm nitrogen, or between 100 and 150 ppm nitrogen.

[0084] Cleaners:The metal detergent that can be included in the lubricating fluid described herein generally comprises a polar head with a long hydrophobic tail, wherein the polar head comprises a metal salt of an acidic organic compound. The salt can contain a substantially stoichiometric amount of metal, in which case they are generally described as normal salts or neutral salts, and generally have a total base number or TBN (as measured by ASTM D2896) of 0 to less than 150. By reacting an excess of a metallic compound (such as an oxide or hydroxide) with an acidic gas (such as carbon dioxide), a large amount of metallic alkali can be included. The resulting high alkaline detergent comprises micelles of a neutralizing detergent around an inorganic metal base (such as a hydrated carbonate) core. This type of high alkaline detergent can have a TBN of 150 or higher, such as 150 to 450 or higher.

[0085] Detergents that may be suitable for use in embodiments of the present invention include oil-soluble high-based, low-based, and neutral sulfonates, phenates, sulfurized phenates, and metal salicylates, particularly alkali metals or alkaline earth metals, such as sodium, potassium, lithium, calcium, and magnesium. More than one metal may be present, such as calcium and magnesium. Mixtures of calcium and / or magnesium with sodium may also be suitable. Suitable metal detergents may be high-based calcium or magnesium sulfonates having a TBN of 150 to 450 TBN, high-based calcium or magnesium phenates or sulfurized phenates having a TBN of 150 to 300 TBN, and high-based calcium or magnesium salicylates having a TBN of 130 to 350. Mixtures of these salts may also be used.

[0086] The metal-containing detergent may be present in the lubricating fluid in an amount sufficient to improve the rust prevention properties of the fluid. The metal-containing detergent may be present in the fluid in an amount sufficient to provide up to 200 ppm of alkali metal and / or alkaline earth metal, based on the total weight of the lubricating fluid. In one embodiment, the metal-containing detergent may be present in an amount sufficient to provide 100 to 200 ppm of alkali metal and / or alkaline earth metal. In another embodiment, the metal-containing detergent may be present in an amount sufficient to provide 100 to 150 ppm of alkali metal and / or alkaline earth metal.

[0087] Corrosion Inhibitors: Rust inhibitors or corrosion inhibitors may also be included in the lubricating compositions described herein. These include monocarboxylic acids and polycarboxylic acids. Examples of suitable monocarboxylic acids are octanoic acid, decanoic acid, and dodecanoic acid. Suitable polycarboxylic acids include dimer and trimer acids, such as those produced from acids such as tall oil fatty acid, oleic acid, linoleic acid, or their analogs. Suitable copper corrosion inhibitors include etheramines, polyethoxylated compounds such as ethoxylated amines and ethoxylated alcohols, imidazolines, monoalkyl and dialkyl thiadiazoles, and the like. Additional compounds include monocarboxylic acids and polycarboxylic acids. Examples of suitable monocarboxylic acids are octanoic acid, decanoic acid, and dodecanoic acid. Suitable polycarboxylic acids include dimer and trimer acids, such as those produced from acids such as tall oil fatty acid, oleic acid, linoleic acid, or their analogs.

[0088] Thiazoles and triazoles can also be used in lubricants. Examples include benzotriazole; tolyltriazole; octyltriazole; decyltriazole; dodecyltriazole; and 2-mercaptobenzotriazole.

[0089] Another type of useful rust inhibitor may be alkenyl succinic acid and alkenyl succinic anhydride corrosion inhibitors, such as, for example, tetrapropylene succinic acid, tetrapropylene succinic anhydride, tetradecenyl succinic acid, tetradecenyl succinic anhydride, hexadecenyl succinic acid, hexadecenyl succinic anhydride, and the like. Also useful are half esters of alkenyl succinic acids having 8 to 24 carbon atoms in the alkenyl group with alcohols such as polyethylene glycol. Other suitable rust inhibitors or corrosion inhibitors include etheramines; acid phosphates; amines; polyethoxylated compounds such as ethoxylated amines, ethoxylated phenols, and ethoxylated alcohols; imidazolines; aminosuccinic acid or its derivatives, and the like.

[0090] Mixtures of such rust or corrosion inhibitors may be used.When present in the lubricating compositions described herein, the total amount of corrosion inhibitors may range from up to 1.0 wt% or from 0.01 to 0.5 wt%, based on the total weight of the lubricating composition.

[0091] Extreme pressure agents: The lubricating fluids described herein may optionally include one or more extreme pressure (EP) agents. EP agents soluble in oil include sulfur-containing and chlorine-containing EP agents, chlorinated hydrocarbon EP agents, and phosphorus EP agents. Examples of such EP agents include: chlorinated waxes; organic sulfides and polysulfides, such as dibenzyl disulfide, bis(chlorobenzyl) disulfide, dibutyl tetrasulfide, methyl sulfide of oleic acid, sulfide of alkylphenols, sulfide of dipentenes, sulfide of terpenes, and sulfide of Diels-Alder adducts; phosphosulfurized hydrocarbons, such as the reaction product of phosphorus sulfide with turpentine or methyl oleate; phosphoesters, such as di- and tri-alkyl phosphites, for example, dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, amylphenyl phosphite; diamylphenyl phosphite, tridecyl phosphite, distearyl phosphite, and phenyl phosphites substituted with polypropylene; metal thiocarbamates, such as zinc dioctyldithiocarbamate and barium heptylphenol dioate; amine salts of alkyl and dialkylphosphoric acids, including, for example, amine salts of the reaction product of dialkyldithiophosphoric acids with propylene oxide; and mixtures thereof.

[0092] anti-wear agentsThe lubricating oil composition herein may optionally contain one or more additional antiwear agents. Examples of suitable antiwear agents include, but are not limited to, phosphate esters or salts thereof; phosphate esters; phosphites; phosphonates, phosphorus-containing carboxylates, ethers or amides; oil-soluble amine salts of phosphorus-containing compounds, sulfurized olefins; compounds containing thiocarbamates, including thiocarbamates, alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamoyl)disulfides; and mixtures thereof.

[0093] Antiwear agents may be present in ranges including from about 0 wt % to about 1 wt %, in other approaches from about 0.01 wt % to about 0.8 wt %, in other approaches from about 0.05 wt % to about 0.5 wt %, or in still further approaches from about 0.1 wt % to about 0.3 wt % of the lubricating oil composition.

[0094] Viscosity modifiers: The lubricating fluid may optionally contain one or more viscosity modifiers. Suitable viscosity modifiers may include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutylene, hydrogenated styrene-isoprene polymers, styrene / maleate copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, α-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkyl styrenes, hydrogenated alkenyl aryl conjugated diene copolymers, or mixtures thereof. Viscosity modifiers may include star polymers, and suitable embodiments are described in U.S. Publication No. 2012 / 0101017 A1.

[0095] In addition to or in lieu of a viscosity modifier, the lubricating fluids described herein may optionally contain one or more dispersant viscosity modifiers. Suitable dispersant viscosity modifiers may include functionalized polyolefins, such as ethylene-propylene copolymers functionalized with the reaction product of an acylating agent (such as maleic anhydride) and an amine; polymethacrylates functionalized with amines; or esterified maleic anhydride-styrene copolymers reacted with amines.

[0096] The total amount of viscosity modifier and / or dispersant viscosity modifier, when present, may be up to 1.0 wt%, or up to 0.5 wt%, or up to 0.3 wt%, based on the total weight of the lubricating fluid.

[0097] Dispersants: The lubricating fluid may include one or more dispersants. The dispersant may be an ashless dispersant having a polar group attached to a relatively high molecular weight hydrocarbon chain. Examples of such dispersants include N-substituted long chain alkenyl succinimides, succinate dispersants, succinate-amide dispersants, Mannich base dispersants, polymeric polyamine dispersants, phosphorylated forms thereof, and borated forms thereof. The dispersant may be end-capped with an acidic molecule capable of reacting with a secondary amino group.

[0098] The N-substituted long chain alkenyl succinimide may include a polyisobutylene (PIB) substituent, wherein the number average molecular weight of the polyisobutylene substituent is in the range of about 500 to 5000. The PIB substituent used in the dispersant also has a viscosity of about 2100 to about 2700 cSt at 100° C. as determined according to ASTM D445.

[0099] The polyisobutylene portion of the dispersant preferably has a narrow molecular weight distribution (MWD), also known as polydispersity, as determined by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). Polymers having an Mw / Mn of less than 2.2, preferably less than 2.0, are most desirable. Suitable polyisobutylene substituents have a polydispersity of about 1.5 to 2.1, or about 1.6 to about 1.8.

[0100] The dicarboxylic acid or anhydride can be selected from carboxylic acid reactants such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethylmaleic anhydride, dimethylmaleic anhydride, ethylmaleic acid, dimethylmaleic acid, hexylmaleic acid, and the like, including the corresponding acid halides and C1-C4 aliphatic esters. The molar ratio of the dicarboxylic acid or anhydride to the hydrocarbyl moiety in the reaction mixture used to prepare the hydrocarbyl-dicarboxylic acid or anhydride can vary widely. Thus, the molar ratio can vary from 5:1 to 1:5, for example, from 3:1 to 1:3. A particularly suitable molar ratio of the acid or anhydride to the hydrocarbyl moiety is from 1:1 to less than 1.6:1. Another useful molar ratio of the dicarboxylic acid or anhydride to the hydrocarbyl moiety is from 1.3:1 to 1.7:1, or from 1.3:1 to 1.6:1, or from 1.3:1 to 1.5:1.

[0101] Any of a number of polyalkylene polyamines can be used as a dispersant additive. Non-limiting exemplary polyamines can include aminoguanidine bicarbonate (AGBC), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA) and heavy polyamines. Heavy polyamines can include a mixture of polyalkylene polyamines with a small amount of polyamine oligomers, such as TEPA and PEHA, but mainly oligomers with seven or more nitrogen atoms, two or more primary amines per molecule, and more extensive branching than conventional polyamine mixtures. Typically, these heavy polyamines have an average of 6.5 nitrogen atoms per molecule. Other non-limiting polyamines that can be used to prepare hydrocarbyl-substituted succinimide dispersants are disclosed in U.S. Patent No. 6,548,458, the disclosure of which is incorporated herein by reference in its entirety. The molar ratio of the hydrocarbyl-dicarboxylic acid or anhydride to the polyalkylene polyamine can be from about 1:1 to about 3.0:1.

[0102] Mannich base dispersants can be the reaction product of an alkylphenol (typically having long chain alkyl substituents on the ring) with one or more aliphatic aldehydes containing from about 1 to about 7 carbon atoms, particularly formaldehyde and its derivatives, and a polyamine, particularly a polyalkylene polyamine. For example, a Mannich base ashless dispersant can be formed by condensing a long chain hydrocarbon-substituted phenol with about 1 to about 2.5 moles of formaldehyde in a molar ratio of about 0.5 to about 2 moles of a polyalkylene polyamine.

[0103] The dispersants described herein may be boronated and / or phosphated. Such dispersants are typically the reaction product of i) at least one phosphorus compound and / or boron compound and ii) at least one ashless dispersant.

[0104] Suitable boron compounds that can be used to form the dispersants herein include any boron compound or mixture of boron compounds that can introduce boron-containing substances into the ashless dispersant. Any organic or inorganic boron compound that can carry out this reaction can be used. Therefore, boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF4 Boric acid such as borous acid (for example alkyl-B (OH) 2 or aryl-B (OH) 2), boric acid (i.e. H3BO3), tetraboric acid (i.e. H2BO7), metaboric acid (i.e. HBO2), ammonium salts of such boric acids and esters of such boric acids can be used. Using a complex of boron trihalide with ether, organic acid, inorganic acid or hydrocarbon is a convenient method for introducing the boron reactant into the reaction mixture. Such complexes are known, such as boron trifluoride-diethyl ether, boron trifluoride-phenol, boron trifluoride-phosphoric acid, boron trichloride-chloroacetic acid, boron tribromide-dioxane and boron trifluoride-methyl ethyl ether.

[0105] Suitable phosphorus compounds for forming the dispersants herein include phosphorus compounds or mixtures of phosphorus compounds that are capable of introducing phosphorus-containing species into the ashless dispersant. Thus, any organic or inorganic phosphorus compound capable of undergoing such a reaction may be used. Thus, inorganic phosphorus compounds such as inorganic phosphoric acid and inorganic phosphorus oxides, including their hydrates, may be used. Typical organophosphorus compounds include full and partial esters of phosphoric acid, such as monoesters, diesters, and triesters of phosphoric acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid, and tetrathiophosphoric acid; monoesters, diesters, and triesters of phosphorous acid, thiophosphorous acid, dithiophosphorous acid, and trithiophosphorous acid; trihydrocarbylphosphine oxides; trihydrocarbylphosphine sulfides; mono- and dihydrocarbylphosphonates (RPO(OR′)(OR″), wherein R and R′ are hydrocarbyl groups, and R″ is a hydrogen atom or a hydrocarbyl group) and their mono-, di-, and trithio analogs; mono- and dihydrocarbylphosphinates (RP(OR′)(OR″), wherein R and R′ are hydrocarbyl groups, and R″ is a hydrogen atom or a hydrocarbyl group) and their mono- and dithio analogs; and the like. Thus, compounds such as phosphorous acid (H3PO3, sometimes described as H2(HPO3) and sometimes called orthophosphorous acid or phosphonic acid), phosphoric acid (H3PO4, sometimes called orthophosphoric acid), hypophosphorous acid (H4P2O6), metaphosphoric acid (HPO3), pyrophosphoric acid (H4P2O7), hypophosphorous acid (H3PO2, sometimes called phosphinic acid), pyrophosphorous acid (H4P2O5, sometimes called pyrophosphoric acid), phosphinic acid (H3PO), tripolyphosphoric acid (H5P3O10), tetrapolyphosphoric acid (H5P4O 13 ), trimetaphosphoric acid (H3P3O9), phosphorus trioxide, phosphorus tetroxide, phosphorus pentoxide, etc. Partial sulfur or full sulfur analogs such as tetrathiophosphoric acid (H3PS4), thiophosphoric acid (H3PO3S), dithiophosphoric acid (H3PO2S2), trithiophosphoric acid (H3POS3), phosphorus sesquisulfide, phosphorus heptasulfide and phosphorus pentasulfide (P2S5, sometimes called P4S 10 ), can also be used to form the dispersant of the present disclosure. Inorganic phosphorus halides such as PCl3, PBr3, POCl3, PSCl3, etc. can also be used.

[0106] Likewise, organophosphorus compounds may be used, such as monoesters, diesters, and triesters of phosphoric acid (e.g., trihydrocarbyl phosphates, dihydrocarbyl monophosphates, monohydrocarbyl diacid phosphates, and mixtures thereof), monoesters, diesters, and triesters of phosphorous acid (e.g., trihydrocarbyl phosphites, dihydrocarbyl hydrogen phosphites, hydrocarbyl diacid phosphites, and mixtures thereof), phosphonates ("primary" RP(O)(OR)2 and "secondary" R2P(O)(OR)), phosphinates, phosphonyl halides (e.g., RP(O)Cl2 and R2P(O)Cl), halogenated phosphites, Phosphites (e.g., (RO)PCI2 and (RO)2PCI), halophosphates (e.g., ROP(O)Cl2 and (RO)2P(O)Cl), tertiary pyrophosphates (e.g., (RO)2P(O)-OP(O)(OR)2), and fully or partially sulfur analogs of any of the foregoing organophosphorus compounds, wherein each hydrocarbyl group contains up to about 100 carbon atoms, preferably up to about 50 carbon atoms, more preferably up to about 24 carbon atoms, and most preferably up to about 12 carbon atoms. Halophosphine halides (e.g., hydrocarbyl phosphorus tetrahalides, dihydrocarbyl phosphorus trihalides, and trihydrocarbyl phosphorus dihalides) and halophosphines (monohalogenated and dihalogenated phosphines) may also be used.

[0107] The lubricants described herein may include mixtures of one or more of the above-described boronated and phosphated dispersants in combination with non-borated and non-phosphated dispersants.

[0108] If used, such dispersants are provided in the lubricant at a treat rate of about 1 to about 5 weight percent, in other embodiments about 1 to about 3 weight percent, and in other embodiments about 1 to about 2 weight percent.

[0109] Defoaming agent: Antifoaming agents used to reduce or prevent the formation of stable foam include silicones, polyacrylates, or organic polymers. Foam suppressors useful in the compositions of the disclosed invention include polysiloxanes, copolymers of ethyl acrylate and 2-ethylhexyl acrylate, and optionally vinyl acetate. When present, the amount of antifoaming agent in the lubricating fluid may be up to 0.1 wt%, or up to 0.08 wt%, or less than 0.07 wt%, based on the total weight of the lubricating fluid.

[0110] Seal swelling agent The fluids of the present disclosure may also include seal swell agents. Seal swell agents, such as esters, adipates, sebacates, esters, phthalates, sulfones, alcohols, alkylbenzenes, substituted sulfolanes, aromatic hydrocarbons, or mineral oils, cause swelling of elastomeric materials used as seals in various engines, motors, and transmissions.

[0111] Alcohol seal swell agents are typically low-volatility linear alkyl alcohols such as decanol, tridecanol, and tetradecanol. Alkylbenzenes that can be used as seal swell agents include dodecylbenzene, tetradecylbenzene, dinonylbenzene, di(2-ethylhexyl)benzene, and the like. Substituted sulfolanes (such as those described in U.S. Patent No. 4,029,588, which is incorporated herein by reference) can also be used as seal swell agents in the compositions according to the present invention. Mineral oils that can be used as seal swell agents in the present disclosure include low-viscosity mineral oils with high cycloparaffin or aromatic content.

[0112] Pour point depressants: The lubricants described herein may optionally contain one or more pour point depressants. Suitable pour point depressants may include maleic anhydride-styrene esters, polymethacrylates, polymethyl methacrylates, polyacrylates, or polyacrylamides, or mixtures thereof. The pour point depressant (when present) may be present in an amount of about 0.001 wt % to about 0.04 wt % based on the total weight of the lubricant.

[0113] Generally speaking, the durable lubricating fluids described herein for electric or hybrid electric motor applications may include additive components within the ranges listed in Table 2.

[0114] Table 2: Durable Lubricating Fluids

[0115]

[0116] The percentages of each component above represent the weight percentage of each component based on the total weight of the lubricating fluid containing the component. The additives used to formulate the compositions described herein can be blended into the base oil individually or in various subcombinations. However, it is also suitable to use an additive concentrate (i.e., additives plus a diluent, such as a hydrocarbon solvent) to blend all components simultaneously. The use of an additive concentrate takes advantage of the mutual compatibility provided by the combination of ingredients when in the form of an additive concentrate. In addition, the use of a concentrate reduces blending time and reduces the possibility of blending errors.

[0117] Example

[0118] The following non-limiting examples illustrate features and advantages of one or more embodiments of the present disclosure.Unless otherwise indicated or apparent from the context of the discussion, all percentages, ratios and parts indicated in the examples and throughout this disclosure are by weight.

[0119] To demonstrate that the fluids selected herein exhibited the desired conductivity, exemplary finished fluids were formulated, aged, and evaluated.

[0120] In the following examples, several formulations were mixed. For each formulation, a first lubricant sample was taken and measured according to ASTM D2624-15 (modified to test lubricants instead of fuels) using an Epsilon+ conductivity meter (Flucon Fluid Control GmbH) or equivalent at 1.5 volts, 20 Hz, and 160°C to obtain at least one conductivity reading. A second lubricant sample was then taken from each formulation and aged for 192 hours at 170°C according to CEC L-48-A-00. After aging, the fluids were allowed to cool to room temperature. After cooling, the conductivity of each aged fluid was measured according to ASTM D2624-15 (modified to test lubricants instead of fuels) using an Epsilon+ conductivity meter (Flucon Fluid Control GmbH) or equivalent at 1.5 volts, 20 Hz, and 160°C to obtain at least one conductivity reading for each aged fluid being evaluated.

[0121] Example 1

[0122] The formulations tested in Table 3 below all contained the same base additive package, which included friction modifiers, detergents, antioxidants, phosphated and boronated dispersants, corrosion inhibitors, and process oil. In addition to the base additive package, the formulations also contained the additional additives noted in Table 3. The formulations varied slightly in process oil treat rates, ranging from approximately 1.75 to approximately 0.43 weight percent of the finished fluid, depending on the amount of thiadiazole or its derivative and / or amine phosphate included in the formulation. The formulations had a total additive treat rate of approximately 5 to approximately 5.5 weight percent and included similar base oils and viscosity modifiers to achieve a kinematic viscosity between approximately 4.9 and 5.9 cSt at 100°C.

[0123] The additives in Table 3 were evaluated for initial and aged conductivity to determine conductivity durability, or the ability of the fluid to maintain a relatively low conductivity after aging. Low conductivity durability is desirable, meaning that the fluid maintains conductivity performance after aging. Table 3 reports the weight percentages of thiadiazole and amine phosphate in the finished fluid, which also included the additive package and base oil as reported above. Total sulfur, phosphorus, and nitrogen, as well as the ratios described, were calculated based on the amounts of these elements provided by the various components in the finished fluid. The conductivity results are provided in Table 4.

[0124] Table 3: Detailed information of relevant fluids

[0125]

[0126] 1-Thiadiazole: An 85:15 mixture of 2,5-bis-(alkyldithio)-1,3,4-thiadiazole and 5-alkyldithio-2-mercapto-1,3,4-thiadiazole, wherein the alkyl group is a C8 to C12 alkyl group. The sulfur source comprises about 35% by weight sulfur and about 6.4% by weight nitrogen.

[0127] Amine salts of 2-phosphate esters: mixtures of dihexyl and monohexyl phosphates with di- and / or trialkylated amines having C12 to C14 alkyl groups. The phosphorus source comprises about 2.5 wt% nitrogen and about 4.9 wt% phosphorus.

[0128] 3- Boronated and phosphated succinimide dispersant derived from 950Mn polyisobutylene and having 0.35 wt% boron and 0.76 wt% phosphorus

[0129] 4-2,6-di-tert-butylphenol

[0130] Table 4: Conductivity results

[0131]

[0132] like Figure 1 As shown, for the inventive samples having a ratio of 2.3 or better and at least about 0.7 weight percent thiadiazole in the fluid, the effect of total fluid sulfur and phosphorus relative to total nitrogen on the conductivity durability of the fluid (i.e., the absolute value of the initial conductivity at 160°C compared to the conductivity after aging at 160°C) is significantly improved. This result is surprising at these total fluid sulfur and phosphorus levels, given that these elements tend to be conductive. Furthermore, given the low molecular weight of thiadiazole, the conductivity of the fluid after aging would be expected to be unacceptably high.

[0133] It should be understood that while the lubricating compositions and compositions of the present disclosure have been described in conjunction with the detailed description and summary herein, the foregoing description is intended to illustrate and not to limit the scope of the disclosure, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are also within the scope of the claims. It is intended that the specification and examples be considered merely exemplary, with the true scope of the disclosure being indicated by the appended claims.

[0134] After considering the practice of this specification and the embodiments disclosed herein, other embodiments of the present disclosure will be apparent to those skilled in the art. As used throughout the specification and claims, "one (a)" and / or "one (an)" may refer to one or more than one. Unless otherwise indicated, all numerals expressing the amount of components and characteristics used in this specification, such as molecular weight, percentage, ratio, reaction conditions, etc., should be understood to be modified by the term "about" in all cases, regardless of whether the term "about" exists. Therefore, unless otherwise indicated, the numerical parameters set forth in this specification are approximate values ​​that may vary depending on the desired characteristics attempted to be obtained by the present disclosure. At a minimum, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying general rounding techniques. Although the numerical ranges and parameters setting forth the wide range of the present disclosure are approximate values, the numerical values ​​set forth in the specific embodiments are reported as accurately as possible. However, any numerical value inherently contains some errors that are inevitably caused by the standard deviation found in its corresponding test measurement value.

[0135] It is to be understood that each component, compound, substituent or parameter disclosed herein is to be interpreted as disclosed for use alone or in combination with one or more of each of the other components, compounds, substituents or parameters disclosed herein.

[0136] It should also be understood that each range disclosed herein is to be interpreted as a disclosure of each specific value having the same number of significant digits within the disclosed range. Thus, a range of 1-4 is to be interpreted as an explicit disclosure of the values ​​1, 2, 3, and 4, as well as any range of these values, e.g., 1-4, 1-3, 1-2, 2-4, 2-3, etc.

[0137] It should also be understood that each lower limit of each range disclosed herein should be interpreted as disclosed in combination with each upper limit of each range and each specific value within each range for the same component, compound, substituent or parameter disclosed herein. Therefore, this disclosure should be interpreted as a disclosure of all ranges obtained by combining each lower limit of each range with each upper limit of each range or each specific value within each range, or by combining each upper limit of each range with each specific value within each range.

[0138] In addition, the specific amounts / values ​​of components, compounds, substituents or parameters disclosed in this specification or the examples should be interpreted as a disclosure of the lower or upper limit of a range, and thus can be combined with the lower or upper limit of any other range or the specific amounts / values ​​of the same components, compounds, substituents or parameters disclosed elsewhere in this application to form the range of the components, compounds, substituents or parameters.

Claims

1. A durable lubricating composition for an electric or hybrid electric vehicle, the lubricating composition comprising: a base oil of lubricating viscosity; at least 0.7% by weight of a thiadiazole or a derivative thereof; an amine salt of a phosphoric acid ester that provides at least 100 ppm of phosphorus to the heavy-duty lubricating composition; a sulfur plus phosphorus to nitrogen ((S+P) / N) weight ratio of at least 2.3; The lubricating composition has at least 150 ppm phosphorus and at least 2000 ppm sulfur; and A conductivity durability of 50,000 pS / m or less, wherein the conductivity durability is the difference between initial and final conductivity, and the initial and final conductivity are measured at 1.5 volts, 20 hertz, and 160 degrees Celsius in accordance with ATSM D2624-15, and wherein the final conductivity is measured after the lubricating composition has been aged at 170°C for 192 hours in accordance with CEC L-48-A-00. 2 . The durable lubricating composition for electric or hybrid electric vehicles according to claim 1 , wherein the thiadiazole is selected from mono-hydrocarbyl mercaptan-substituted thiadiazoles, di-hydrocarbyl mercaptan-substituted thiadiazoles, or combinations thereof. 3 . The durable lubricating composition for electric or hybrid electric vehicles according to claim 1 , wherein the thiadiazole is 1,3,4-thiadiazole or a derivative thereof.

4. The heavy-duty lubricating composition for an electric or hybrid electric vehicle according to claim 1, wherein the thiadiazole provides at least 2000 ppm of sulfur to the heavy-duty lubricating composition.

5. The durable lubricating composition for an electric or hybrid electric vehicle according to claim 4, wherein the durable lubricating composition comprises up to 3500 ppm of total sulfur and up to 300 ppm of total phosphorus; and / or wherein the lubricating composition comprises 1 wt% or less of a thiadiazole or a derivative thereof.

6. The durable lubricating composition for electric or hybrid electric vehicles according to claim 1, wherein the thiadiazole or its derivative comprises one or more compounds having the structure of Formula I: (Formula I) in Each R1 is independently hydrogen or sulfur; Each R2 is independently alkyl; n is an integer of 0 or 1, and if R1 is hydrogen, then the integer n of the adjacent R2 moiety is 0, and if R1 is sulfur, then n of the adjacent R2 moiety is 1; and wherein at least one R1 is sulfur.

7. The durable lubricating composition for electric or hybrid electric vehicles according to claim 1, wherein the phosphate amine salt comprises one or more of monoalkyl phosphate and / or dialkyl phosphate, and wherein the alkyl group thereof may be linear or branched.

8. The durable lubricating composition for electric or hybrid electric vehicles according to claim 7, wherein the amine salt of the phosphate ester is represented by Formula II (Formula II) in R3 and R4 may independently be hydrogen or a linear, branched or cyclic hydrocarbon group; m is an integer from 0 to 1, p is an integer from 1 to 2, and m+p is equal to 2; R5, R6, R7 and R8 may independently be hydrogen or a hydrocarbon group and at least one of R5 to R8 is a hydrocarbon group.

9. The durable lubricating composition for an electric or hybrid electric vehicle according to claim 8, wherein R3 and R4 are independently C3 to C10 alkyl groups; and / or wherein at least one of R5, R6, R7 and R8 is C10 to C20 alkyl groups.

10. The durable lubricating composition for electric or hybrid electric vehicles according to claim 9, wherein two of R5, R6, R7 and R8 are independently C10 to C20 alkyl groups.

11. The durable lubricating composition for electric or hybrid electric vehicles according to claim 1, wherein the amine salt of the phosphate ester provides 40 to 90 weight % of the total phosphorus in the durable lubricating composition.

12. The durable lubricating composition for an electric or hybrid electric vehicle according to claim 11, wherein the thiadiazole or derivative thereof provides at least 99 weight percent of the total sulfur in the durable lubricating composition. 13 . The durable lubricating composition for electric or hybrid electric vehicles according to claim 1 , wherein the lubricating composition comprises 0.25 to 0.5 wt % of the phosphate amine salt.

14. The durable lubricating composition for an electric or hybrid electric vehicle according to claim 1, wherein the lubricating composition has an initial conductivity of 150,000 or less before aging when measured at 1.5 volts, 20 hertz and at 160 degrees Celsius according to ASTM D2624-15.

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