Methods for minimizing conductive deposits

Abstract

The disclosed technology relates to a method for minimizing conductive deposits in conductive equipment by lubricating the equipment with a lubricant containing a borate ester. The disclosed technology provides a method for minimizing conductive deposits in conductive equipment. The method includes applying a lubricant containing an oil of lubricating viscosity and 0.3 to 1 weight percent of a borate ester to the equipment, and applying an electric current. In some embodiments, the lubricant in the method can also contain 0.01 to 1.0 weight percent of a thiadiazole compound. The method helps maintain a wear rating of greater than 10 at 150° C. according to ASTM D5182.

Description

[Technical field]

[0001] The disclosed technology relates to a method of minimizing conductive deposits in conductive equipment while providing adequate wear protection by lubricating the equipment with a lubricant containing a borate ester and a thiadiazole corrosion inhibitor. [Background technology]

[0002] Advances in hybrid and electric vehicles have created a need for new generations of lubricants and new lubricant performance tests. Copper corrosion is one prominent concern in hybrid and electric vehicles and is routinely evaluated using coupon testing. In the presence of lubricating fluids that are corrosive in nature, the appearance of copper coupons may change due to metal dissolution, surface discoloration, or the formation of a corrosion layer. The visual assessment provided at the end of the test is qualitative in nature and does not provide insight into the type of corrosion process occurring, or the chemical kinetics or time dependence of the corrosion process.

[0003] WO 2021 / 155015 describes the development of a copper wire test designed to generate corrosion test results in real time and simultaneously in solution and gas phases. In this test, a known constant current or voltage is passed through a wire of a given thickness and length. The electrical resistance of the wire can be measured at various temperatures over time. If metal dissolution is the cause of corrosion, the measured resistance increases over time as the wire thins and eventually breaks.

[0004] In an electric drive unit, there are multiple sources of electrical potential that can significantly alter the formation of corrosion deposits. The use of the conductive layer deposit test described herein can help determine whether a corrosion mechanism for the fluid is responsible for the formation of corrosion deposits. In this test, a copper printed circuit board (PCB) is immersed in the solution phase of the lubricant and placed in the gas phase above the lubricant as an electric current is passed through the lubricating fluid. Real-time conductivity measurements are made and visual observation of the appearance of the printed circuit board at the end of the test is used to determine whether a corrosion deposit has formed and whether the deposit is conductive or non-conductive.

[0005] Conductive layer deposits are defined as solid formations created by corrosion or lubricant degradation by-products that form undesirable paths of low electrical resistance. The chemical identity of these layers has been investigated and determined to be copper sulfide. The formation of this conductive deposit can result in catastrophic failure of the electric drive unit, either through a direct short circuit of the motor windings or failure of the power electronics. Although this phenomenon is a new area of ​​concern with electric motors and lubricants, the microelectronics industry has been evaluating a similar phenomenon in printed circuit board (PCB) failures since the early 1970s. Figure 1 shows an electric motor failure due to conductive deposits causing a short circuit between electric motor windings.

[0006] Metal corrosion can be a costly and destructive phenomenon. In 2017, at a time when the market share of plug-in vehicles is exceptionally low, the global cost of environmental corrosion of steel was estimated to be $2.5 trillion per year. The addition of electric motors in electric vehicles increases the opportunities for metal corrosion to occur. The corrosion of copper found in electrical components can add significant costs to the figures cited above. As electric vehicle sales increase, corrosion-related effects in electric vehicles may affect the total cost of corrosion both locally and globally.

[0007] Different drivetrain formulations may have inherently different corrosion rates that produce conductive layer deposits in both solution and vapor phases. In some vehicles, the electric motor is integrated into the transmission or axle and is in direct contact with the lubricant, while in other vehicles the path between the lubricant and the electric motor will be limited to the vapor space. The formation of conductive layer deposits has been identified as a failure mechanism for current electric motor designs. One of the long-standing challenges in lubrication science is to provide adequate corrosion protection while providing sufficient wear protection. The combination of a wide variety of electric motor and transmission designs makes it essential to have a robust method to minimize or prevent conductive deposits while providing sufficient wear protection. Thus, the disclosed technology solves the problem of conductive deposits in conductive devices. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2021 / 155015 Summary of the Invention

[0009] The disclosed technology provides a method for minimizing conductive deposits in an electrically conductive device. The method includes applying a lubricant to the device, the lubricant including an oil of lubricating viscosity and 0.3-1 weight percent of a borate ester, and applying an electric current. In some embodiments, the lubricant in the method can also include 0.01-1.0 weight percent of a thiadiazole compound. The method helps maintain a wear rating of greater than 10 at 150° C. according to ASTM D5182. [Brief description of the drawings]

[0010] [Figure 1]eMotor failure caused by copper corrosion [Hunt, G. and Prengaman, C., "Understanding Vapor and Solution Phase Corrosion of Lubricants Used in Electrified Transmissions," SAE Technical Paper 2020-01-0561, 2020, doi:10.4271 / 2020-01-0561]. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Various preferred features and embodiments are described below by way of non-limiting examples.

[0012] One component of the disclosed technology is an oil of lubricating viscosity, also referred to as a base oil. The base oil may be selected from any of the base oils in Groups I to V of the American Petroleum Institute (API) Base Oil Interchangeability Guidelines (2011), namely: Base Oil Category Sulfur (%) Saturates (%) Viscosity Index Group I >0.03 and / or <90 80-120 Group II ≦0.03 and ≧90 80~120 Group III ≦0.03 and ≧90 ≧120 Group IV All polyalphaolefins (PAO) Group V All others not included in Groups I, II, III, or IV

[0013] Groups I, II, and III are mineral oil base stocks. Other commonly recognized categories of base oils may be used even if not officially specified by API, with Group II+ referring to Group II materials having a viscosity index of 110-119 and lower volatility than other Group II oils, and Group III+ referring to Group III materials having a viscosity index of 130 or greater. The oil of lubricating viscosity may include natural or synthetic oils and mixtures thereof. Mixtures of mineral and synthetic oils, such as polyalphaolefin oils and / or polyester oils, may be used. In one embodiment, the oil of lubricating viscosity includes API Group II, or Group III oils, or mixtures thereof.

[0014] The oil of lubricating viscosity (or mixture of such oils) may be a relatively low viscosity oil having a kinematic viscosity of 2.2 to 3.7 mm2 / s, or 2.5 to 3.5 mm2 / s, or 2.8 to 3.3 mm2 / s at 100° C. The use of oils in this viscosity range allows the preparation of lubricant compositions having a kinematic viscosity of 4.7 mm2 / s or less, for example 3.0 to 4.6, or 3.3 to 4.3, or 3.6 to 4.1 mm2 / s, at 100° C.

[0015] The oil of lubricating viscosity (or mixture of such oils) may also be a relatively high viscosity oil having a kinematic viscosity at 100°C.

[0016] The amount of oil of lubricating viscosity may be from 50 to 98 weight percent, or from 60 to 96, or from 70 to 94, or from 80 to 93, or from 85 to 92 weight percent, which amount may be calculated to include the amount of diluent oil normally provided with additive ingredients such as detergents, dispersants, and viscosity modifiers.

[0017] Another component of the disclosed lubricant compositions is at least one borate ester having an alkyl group of 4 to 18 carbon atoms. The borate ester may generally be viewed as an ester of boric acid or its equivalent with an alcohol.

[0018] In one embodiment, the boron-containing compound can be described as a borate ester or a borate alcohol.Borate ester or borate alcohol compounds are substantially the same, except that borate alcohol has at least one hydroxyl group that is not esterified.Therefore, as used herein, the term "borate ester" is used to refer to either borate ester or borate alcohol.

[0019] The borate esters may be prepared by the reaction of a boron compound with at least one compound selected from halohydrin compounds, epihalohydrin compounds, alcohols, and mixtures thereof, including dihydric, trihydric, or higher alcohols, provided that in one embodiment, the hydroxyl groups are on adjacent carbon atoms, i.e., vicinal.

[0020] Suitable boron compounds for preparing borate esters include various forms of boric acid (including metaboric acid, HBO2, orthoboric acid, H3BO3, and tetraboric acid, H2B4O7), boron oxide, boron trioxide, and alkyl borates. Boric acid esters can also be prepared from boron halides.

[0021] In one embodiment, the borate ester is formed by the reaction of a boron compound with a dihydric alcohol, a trihydric alcohol, or a higher alcohol. The borate ester may be represented by at least one of formulas (I)-(VI):

[0022] [ka] wherein each R can be hydrogen or a hydrocarbyl group, provided the borate ester is oil soluble.

[0023] In one embodiment, at least two of the R groups per formula above are hydrocarbyl groups. The hydrocarbyl groups can be alkyl, aryl or cycloalkyl, and any two adjacent R groups are connected in a ring. When R is an alkyl group, the group can be saturated or unsaturated. In one embodiment, the hydrocarbyl group is an unsaturated alkyl. In one embodiment, the hydrocarbyl group is cyclic. In one embodiment, the hydrocarbyl group is a mixture of alkyl and cycloalkyl.

[0024] The number of carbon atoms present in each R can be from 4 to 18, or from 6 to 12. In certain embodiments, the total number of carbon atoms on the R groups can typically be 9 or more, or about 10 or more, or about 12 or more, or about 14 or more.

[0025] Examples of R groups include isopropyl, n-butyl, isobutyl, amyl, 2-pentenyl, 4-methyl-2-pentyl, 2-ethylhexyl, heptyl, isooctyl, nonyl, decyl, undecyl, dodecenyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups.

[0026] The alcohols used for esterification with the boration agent may include monohydric, dihydric, trihydric or higher alcohols. The alcohols may contain 4 to 18 carbon atoms, or 6 to 16 or 6 to 12 carbon atoms.

[0027] Boric acid esters can be prepared by blending a boron compound with an alcohol as described above and heating them at a suitable temperature, such as 80°C to 250°C, 90°C to 240°C, or 100°C to 230°C, until the desired reaction occurs. An inert liquid, such as toluene, xylene, chlorobenzene, dimethylformamide, or mixtures thereof, can be used in carrying out the reaction. Typically, water is formed and distilled during the condensation reaction. An alkaline reagent can be used to catalyze the reaction.

[0028] In one embodiment, suitable borate ester compounds include tripropyl borate, tributyl borate, tripentyl borate, trihexyl borate, triheptyl borate, trioctyl borate, trinonyl borate, and tridecyl borate. In one embodiment, the borate ester compounds include tributyl borate, tri-2-ethylhexyl borate, or mixtures thereof.

[0029] In certain embodiments, the lubricant composition may include a borate ester containing an alkyl group of 4 to 12 carbon atoms, hi other embodiments, the borate ester component may include the reaction product of boric acid with an alcohol of 6 to 12 carbon atoms.

[0030] The amount of borate ester in the lubricant can be 0.2 to 1.1 weight percent, or 0.25 or 0.3 to 1.1 percent, or 0.4 to 1 percent, or 0.45 to 1 weight percent, or 0.2 to 1 percent, or 0.25 to 1 percent, or 0.3 to 1 percent, or 0.3 to 0.8 percent.

[0031] Another component of the disclosed lubricant composition is a thiadiazole compound. The thiadiazole can be a thiadiazole or a hydrocarbyl-substituted thiadiazole. Examples of thiadiazoles include 2,5-dimercapto-1,3,4-thiadiazole, or an oligomer thereof, a hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole, or a hydrocarbylthio-substituted 2,5-dimercapto-1,3,4-thiadiazole, or an oligomer thereof. The oligomer of hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically forms a sulfur-sulfur bond between the 2,5-dimercapto-1,3,4-thiadiazole units to form two or more oligomers of the thiadiazole units.

[0032] Examples of suitable thiadiazole compounds include at least one of dimercaptothiadiazole, 2,5-dimercapto-[1,3,4]-thiadiazole, 3,5-dimercapto-[1,2,4]-thiadiazole, 3,4-dimercapto-[1,2,5]-thiadiazole, or 4-5-dimercapto-[1,2,3]-thiadiazole.Typically, readily available materials, such as 2,5-dimercapto-1,3,4-thiadiazole or hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole or hydrocarbylthio-substituted 2,5-dimercapto-1,3,4-thiadiazole, are commonly available and 2,5-dimercapto-1,3,4-thiadiazole may be most commonly utilized due to its ready availability. In different embodiments, the number of carbon atoms on the hydrocarbyl substituent includes 1-30, 2-25, 4-20, 6-16, or 8-10.

[0033] In one embodiment, the thiadiazole compound can be the reaction product of a phenol with an aldehyde and a dimercaptothiadiazole. The phenol includes an alkylphenol in which the alkyl group contains at least 6, e.g., 6 to 24, or 6 (or 7) to 12 carbon atoms. The aldehyde includes an aldehyde containing 1 to 7 carbon atoms or an aldehyde synthon such as formaldehyde. Useful thiadiazole compounds include 2-alkyldithio-5-mercapto-[1,3,4]-thiadiazole, 2,5-bis(alkyldithio)-[1,3,4]-thiadiazole, 2-alkyl-hydroxyphenylmethylthio-5-mercapto[1,3,4]-thiadiazole (e.g., 2-[5-heptyl-2-hydroxyphenylmethylthio]-5-mercapto-[1,3,4]-thiadiazole), and mixtures thereof.

[0034] In one embodiment, the thiadiazole compound comprises at least one of 2,5-bis(tert-octyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole, or 2,5-bis(tert-decyldithio)-1,3,4-thiadiazole. In yet another embodiment, the thiadiazole comprises at least one of 1,3,4-thiadiazole, 2,5-bis(tert-nonyldithio), 2-(heptylhydroxyphenylmethylthio)-5-mercapto-[1,3,4]-thiadiazole, or mixtures thereof.

[0035] The amount of the thiadiazole compound in the lubricant can be 0.01 to 1.0 weight percent, or 0.02 or 0.03 to 0.9 percent, or 0.04 to 0.8 percent, or 0.05 to 0.7 weight percent, or 0.06 to 0.6 percent, or 0.07 to 0.5 percent.

[0036] Other conventional additives may also optionally be present in amounts conventionally used for automatic transmission lubricants, including, for example, phosphorus esters, viscosity modifiers, dispersants, foam suppressors, friction modifiers, antioxidants, detergents, corrosion inhibitors, extreme pressure / antiwear agents, and seal swell agents.

[0037] In one embodiment, the lubricant may contain at least one phosphorus ester in an amount to provide the composition with 150 to 650, or 150 to 350, or 180 to 250 parts per million by weight phosphorus. The amount of the at least one phosphorus ester is 0.05 to 0.4 weight percent, or 0.1 to 0.35 percent.

[0038] The phosphorus ester may include a C4-C8 or C4-C6 alkyl phosphite, such as dioctyl phosphite, or alternatively an oligomeric phosphite which is the reaction product of a monomeric phosphorous acid or ester with an alkylene diol.

[0039] The C4-C6 alkyl phosphites can include dialkyl phosphites such as dibutyl phosphite, dihexyl phosphite, and dicyclohexyl phosphite. Such materials are readily available commercially.

[0040] Oligomeric phosphites are described in more detail in WO 2016 / 089565, Abraham et al. (Lubrizol), June 9, 2016. Briefly, they can be described as the reaction product of (a) a monomeric phosphoric acid or ester thereof with (b) at least two alkylene diols. The first alkylene diol (i) has two hydroxy groups in a 1,4 or 1,5 or 1,6 relationship on the carbon chain, and the second alkylene diol (ii) is an alkyl-substituted 1,3-propylene diol having one or more alkyl substituents on one or more carbon atoms of the propylene units. The total number of carbon atoms in the alkyl-substituted 1,3-propylene diol is 5 to 12. In the oligomeric phosphite, the relative molar amounts of the monomeric phosphorous acid or ester thereof (a) and the total alkylene diol (b) are typically in a ratio of about 0.9:1.1 to about 1.1:0.9, and the relative molar amounts of the first alkylene diol (i) and the alkyl-substituted 1,3-propylene diol (ii) are typically in a ratio of 30:70 to 65:35, or alternatively 35:54 to 60:40, or 50:60 to 50:50, or 40:60 to 45:55.

[0041] The first alkylene diol can be branched (e.g., alkyl-substituted) or unbranched, and in one embodiment is unbranched. Unbranched, i.e., straight-chain diols (α,ω-diols) include 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. Branched or substituted diols include 1,4-pentanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 3,3-dimethyl-1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, and 2,5-dimethyl-2,5-hexanediol. For the purposes of the disclosed technology, diols with one or more secondary hydroxyl groups (such as 2,5-hexanediol) can be referred to as branched or substituted diols, even if the carbon chain itself can be straight-chained. The location of the hydroxy groups at the 1,4, 1,5, or 1,6 positions (i.e., relative to each other or literally) may help promote oligomerization with the phosphorus species rather than the formation of periodic structures (which is sterically unfavorable). In certain embodiments, the first alkylene diol may be 1,6-hexanediol.

[0042] The first alkylene dihydroxy compound (diol) may optionally have additional hydroxy groups, i.e., more than two or exactly two per molecule. In one embodiment, there are exactly two hydroxy groups per molecule. If there are more than two hydroxy groups, but there are less than four atoms separating any of the hydroxy groups, care must be taken to ensure that there is no excessive cyclization, which may interfere with the polymerization reaction. Care must also be taken to avoid excessive branching or crosslinking in the product, which may lead to undesirable gel formation. Such problems can be avoided by careful management of the reaction conditions, for example, managing the ratio of reagents and their order of addition, carrying out the reaction under suitable dilution conditions, and reacting under low acid conditions. These conditions can be determined by one of ordinary skill in the art using only routine experimentation.

[0043] The second alkylene diol is an alkyl substituted 1,3-propylene diol having one or more of its alkyl substituents on one or more of the carbon atoms of the propylene unit, and the total number of carbon atoms of the alkyl substituted 1,3-propylene diol is 5 to 12, or 6 to 12, or 7 to 11, or 8 to 18, or in certain embodiments, 9. That is, the alkyl substituted 1,3-propylene diol may be represented by the following general formula:

[0044] [ka] The various R groups herein may be the same or different and may be hydrogen or alkyl groups, provided that at least one R is an alkyl group, and the total number of carbon atoms in the R groups is 2-9 or 3-9, such that the total carbon atoms in the diol is 5-12 or 6-12, respectively, and similarly for the other total carbon ranges. As with the 1,4-diols, 1,5-diols, or 1,6-diols described above, references herein to 1,3-diols mean that the two hydroxy groups are in a 1,3 relationship to each other, i.e., separated by a chain of three carbon atoms. Thus, 1,3-diols may also be referred to as 2,4-diols or 3,5-diols. If a 1,3-diol has one or more secondary hydroxy groups, such a molecule would be considered a substituted diol. In one embodiment, the number of alkyl substituents is two, and the total number of carbon atoms in the molecule is nine. Suitable substituents may include, for example, methyl, ethyl, propyl, and butyl (their various possible isomers).

[0045] Examples of the second alkylene diol may include 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butylpropane-1,3-diol, 2-ethylhexane-1,3-diol, 2,2-dibutylpropane-1,3-diol, 2,2-diisobutylpropane-1,3-diol, 2-methyl-2-propyl-propane-1,3-diol, 2-propyl-propane-1,3-diol, 2-butylpropane-1,3-diol, 2-pentylpropane-1,3-diol, 2-methyl-2-propylpropane-1,3-diol, 2,2-diethylpropane-1,3-diol, 2,2,4-trimethylpentane-1,3-diol, 2-methylpentane-2,4-diol, 2,4-dimethyl-2,4-pentanediol, and 2,4-hexanediol. It should be noted that some of the aforementioned nomenclature emphasizes the propane-1,3-diol structure of the molecule for clarity. For example, 2-pentylpropane-1,3-diol is sometimes called 2-hydroxymethylheptan-1-ol, although the latter nomenclature does not exemplify the 1,3-nature of the diol very clearly.

[0046] One or more phosphorus esters provide a certain amount of phosphorus to the lubricant composition as indicated above, but the total amount of phosphorus in the lubricant may be in a higher range, e.g., 150 to 1000, or 200 to 800 parts per million by weight. Additional phosphorus may be provided by a different phosphorus-containing species, such as phosphoric acid or an inorganic phosphorus acid, such as phosphorous acid. Phosphoric acid may be commercially available as an 85 weight percent composition with 15 percent water, an appropriate amount of which may be used. Other phosphorus sources may include phosphorus-treated (phosphorus-containing) dispersants, such as the post-treated succinimide dispersants described below.

[0047] The lubricant composition of the disclosed technology may further include a viscosity modifier, also referred to as a viscosity index modifier or viscosity index improver, in certain embodiments. Viscosity modifiers (VMs) and dispersant viscosity modifiers (DVMs) are well known. Examples of VMs and DVMs may include polymethacrylates, polyacrylates, polyolefins, hydrogenated vinyl aromatic-diene copolymers (e.g., styrene-butadiene, styrene-isoprene), styrene-maleic ester copolymers, and similar polymeric materials including homopolymers, copolymers, graft copolymers, including polymers with linear, branched, or star structures. DVMs may include nitrogen-containing methacrylate polymers, such as poly(meth)acrylates containing nitrogen-containing dispersant monomers, or nitrogen-containing olefin polymers, such as nitrogen-containing methacrylate polymers derived from methyl methacrylate and dimethylamino-propylamine. Alternatively, the DVM may comprise a copolymer of units derived from an α-olefin and units derived from a carboxylic acid or anhydride, such as maleic anhydride, partially esterified with a branched primary alcohol and partially reacted with an amine-containing compound.

[0048] Examples of commercially available VMs, DVMs and their chemical types include: polyisobutylenes (such as Indopol™ from BP Amoco or Parapol™ from ExxonMobil); olefin copolymers (such as Lubrizol® 7060, 7065, and 7067 from Lubrizol, and Lucant® HC-2000L, HC-1100, and HC-600); hydrogenated styrene-diene copolymers (such as Shellvis™ 40 and 50 from Shell, and LZ® 7308 and 7318 from Lubrizol); styrene / maleate copolymers, which are dispersant copolymers (such as LZ® 3702 and 3715 from Lubrizol). polymethacrylates, some of which have dispersant properties (such as in the Viscoplex™ series from RohMax, the Hitec™ series of viscosity index improvers from Afton, and LZ® 7702, LZ® 7727, LZ® 7725, and LZ® 7720C from Lubrizol); olefin-graft-polymethacrylate polymers (such as Viscoplex™ 2-500 and 2-600 from RohMax); and hydrogenated polyisoprene star polymers (such as Shellvis™ 200 and 260 from Shell).

[0049] The VM or DVM may have a number average molecular weight of 5,000 to 25,000, or 10,000 to 20,000, or 12,000 to 18,000. The number average molecular weight will be proportionally lower, such as 3,000 to 15,000, or 6,000 to 12,000. The materials in question typically have a relatively low molecular weight compared to VMs and DVMs that may be commonly used in other applications, such as lubricants for internal combustion engines.

[0050] In one embodiment, the viscosity index modifier may include a linear polymer viscosity modifier having dispersant functionality, the linear polymer having a weight average molecular weight of 5000 to 25000 or 10,000 to 20,000, the linear polymer being present in an amount of about 0.1 to about 4 weight percent. In one embodiment, the viscosity index modifier may include a linear polymer as described herein and a polymer having a star structure, for example, a (meth)acrylic type star polymer as disclosed in WO 2007 / 127660, Lubrizol, Nov. 8, 2007.

[0051] Viscosity modifiers that can be used are described in U.S. Patent Nos. 5,157,088, 5,256,752, and 5,395,539. The VM and / or DVM can be used in the functional fluid at concentrations up to 50% or 20% by weight, depending on the application. Concentrations of 0.1-20% by weight, or 0.5-20% by weight, or 1-20% by weight, or 1-12% by weight, or 3-10% by weight, or 0.1-4% by weight, or 1-4% by weight, or alternatively 20-40% by weight, or 20-30% by weight of the lubricant composition can be used. Selection of the amount of viscosity modifier is within the ability of one skilled in the art and will be an amount which, in combination with the viscosity of the base oil, provides the lubricant composition with a kinematic viscosity at 100°C of 4.7 mm2 / s or less, for example 2.7 to 4.7, or 2.8 to 4.7, or 3.4 to 4.0, or 3.5 to 3.9 mm2 / s.

[0052] The lubricant compositions of the disclosed technology may also include one or more dispersants, such as succinimide dispersants, which may, in some cases, provide additional boron content to the lubricant composition. Succinimide dispersants are sometimes referred to as ashless dispersants, and are so named because, as provided, they do not contain metals and therefore do not typically contribute to sulfated ash when added to a lubricant (although boron content contained in borated detergents may contribute to sulfated ash). However, ashless dispersants may of course interact with surrounding metals when added to a lubricant that contains metal-containing species. Ashless dispersants are characterized by a polar group attached to a relatively high molecular weight hydrocarbon chain. Typical ashless dispersants include N-substituted long chain alkenyl succinimides, which typically have a variety of chemical structures, including abbreviated structures.

[0053] [ka] In the formula, each R 1 are independently an alkyl group, often a polyisobutylene group having a molecular weight (Mn) of 500 to 5000 based on a polyisobutylene precursor; R 2 is an alkylene group, typically an ethylene (C2H4) group. Such molecules are typically derived from the reaction of an alkenyl acylating agent with a polyamine. In addition to the simple imide structure shown above, a wide variety of linkages between the two moieties are possible, including a variety of amides and quaternary ammonium salts. Similarly, a variety of structures for the polyamine component are known to be possible, including a variety of cyclic structures. Additionally, in the above structure, the amine portion is shown as an alkylene polyamine, although other aliphatic and aromatic mono- and polyamines may also be used. Also, the attachment of R to the imide structure, including a variety of cyclic linkages, is known to be possible. 1 Various modes of attachment of the groups are possible. The ratio of the carbonyl groups of the acylating agent to the nitrogen atoms of the amine may be from 1:0.5 to 1:3, and in other cases from 1:1 to 1:2.75 or from 1:1.5 to 1:2.5. Succinimide dispersants are more fully described in U.S. Pat. Nos. 4,234,435 and 3,172,892 and European Patent No. 0 355 895.

[0054] Dispersants may also be post-treated by reaction with any of a variety of agents. Among these are urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbyl-substituted succinic anhydrides, nitriles, epoxides, boron compounds, and phosphorus compounds. References detailing such treatments are listed in U.S. Patent No. 4,654,403.

[0055] In particular, the succinimide dispersants used in the disclosed technology may optionally be borated in one embodiment, so as to contain and provide boron to the lubricant formulation. The borated dispersants may be prepared by boration using a variety of agents, such as any of the various forms of boric acid (including metaboric acid, HBO2, orthoboric acid, H3BO3, and tetraboric acid, H2B4O7), boron oxide, boron trioxide, and alkyl borates. In one embodiment, the borating agent is boric acid, which may be used alone or in combination with other borating agents.

[0056] The borated dispersants may be prepared by blending a boron compound with a succinimide dispersant and heating them at a suitable temperature, typically 80°C to 250°C, 90°C to 230°C, or 100°C to 210°C, until the desired reaction occurs. An inert liquid may be used in carrying out the reaction. The liquid may include toluene, xylene, chlorobenzene, dimethylformamide, or mixtures thereof. The boron-containing succinimide dispersants may have a boron content of 0.5 to 1.0 weight percent, or 0.6 to 0.9, or 0.54 to 0.85, or 0.56 to 0.83 weight percent.

[0057] The borated succinimide dispersants may also be products containing additional functional groups by post treatment, for example: (i) Succinimide dispersants; (ii) a borating agent; and (ii) optionally, 2,5-dimercapto-1,3,4-thiadiazole or hydrocarbyl-substituted 2,5-di-mercapto-1,3,4-thiadiazole ("DMTD"), or an oligomer thereof; (iv) optionally, a dicarboxylic acid of an aromatic compound selected from the group consisting of 1,3 diacids and 1,4 diacids; and (v) optionally prepared by heating together a phosphoric acid compound; The heating is sufficient to provide a product of (i), (ii), and optionally (iii), (iv) and / or (v), which is soluble in oil of lubricating viscosity. In one embodiment the borated succinimide dispersant is further treated with a dimercaptothiadiazole.

[0058] The dispersant component may also include a mixture of distinct dispersant species, including untreated (non-borated) succinimide dispersants, borated succinimide dispersants, DMTD treated dispersants, and terephthalic acid treated dispersants. Alternatively, some or all of the post-treatment may be applied to some or all of the succinimide dispersant species. In one embodiment, for example, some or all of the succinimide dispersants may be borated and treated with dimercaptothiadiazole, and optionally further with terephthalic acid. In one embodiment, there may be a mixture of borated succinimide dispersants and borated and DMTD treated dispersants. In a particular embodiment, the dispersant component may include 1 to 4 weight percent of a borated succinimide dispersant that is not treated with dimercaptothiadiazole, and 0.1 to 1.5 weight percent of a borated succinimide dispersant that is treated with dimercaptothiadiazole.

[0059] The components for preparing the post-treated succinimide dispersant may be combined and reacted in any order. In particular, the boration agent may be a pre-treatment or post-treatment process. Thus, for example, boric acid (and optionally phosphoric acid) may be reacted with the dispersant substrate in one step, and then the intermediate borated dispersant may be reacted with the mercaptothiadiazole and aromatic dicarboxylic acid. Alternatively, the dispersant substrate, aromatic dicarboxylic acid and mercaptothiadiazole may be reacted first, and then the product may be treated with the boration agent (and optionally phosphoric acid, phosphorous acid). In yet another variation, the phosphorylated succinimide dispersant may be prepared by reacting phosphoric acid with a hydrocarbyl-substituted succinic anhydride to prepare a mixed anhydride-acid precursor, and then reacting the precursor with a polyamine to form the phosphorus-containing dispersant. The phosphorus-containing dispersant may then be reacted with the aromatic dicarboxylic acid and mercaptothiadiazole, and the boration agent.

[0060] The components are typically reacted with the boration agent and optionally other agents by heating with the dispersant substrate for a time and temperature sufficient to ensure solubility of the resulting product, typically 80-200° C., or 90-180° C., or 120-170° C., or 150-170° C. The reaction time is typically at least 0.5 hours, e.g., 1-24 hours, 2-12 hours, 4-10 hours, or 6-8 hours.

[0061] The amount of the succinimide dispersant component (alternatively, specifically, the boron-containing succinimide dispersant) in the fully formulated lubricant of the present technology, when present, can be at least 0.1%, or at least 0.3%, or 0.5%, or 1%, or 1.5%, and in certain embodiments up to 9%, or 8%, or 6%, or 4%, or 3%, or 2%, by weight of the lubricant composition, for example, 1.1 to 5.5% or 1.0 to 3.5 weight percent. The amount of boron provided to the lubricant formulation by the borated succinimide dispersant component can be from 0 to 270 parts per million by weight, or from 30, 50, 60, 70, or 100 ppm, up to 270, 250, 225, 200, 180, or 140 ppm. In certain embodiments, the succinimide dispersant component may provide from about 10 to about 250 parts per million by weight, or from 20 to 200, or from 50 to 150 ppm of sulfur to the composition due to the presence of the dimercaptothiadiazole moiety present therewith.

[0062] The lubricant compositions of the disclosed technology may also include one or more foam inhibitors. Antifoam agents used to reduce or prevent the formation of stable foam include silicones, fluorosilicones, or organic polymers such as acrylate, fluoroacrylate, or fluoromethacrylate polymers. Examples of these and additional antifoam compositions are described in "Foam Control Agents" by Henry T. Kerner (Noyes Data Corporation, 1976), pages 125-162. They may typically be present in amounts of 20-250 or 50-200 parts per million (excluding diluents). Various combinations of antifoam agents may be used: for example, a first antifoam agent derived from a first antifoam composition comprising a polydimethylsiloxane dispersed or dissolved in an aromatic oil or a naphthenic hydrocarbon solvent, the first antifoam composition having a kinematic viscosity in the range of 10,000 to 50,000 mm2 / s at 25°C (solvent free); a second antifoam agent comprising a polydimethylsiloxane dispersed or dissolved in an aromatic oil or a naphthenic hydrocarbon solvent, the second antifoam agent having a kinematic viscosity in the range of 80,000 to 120,000 mm2 / s at 25°C (solvent free); and a third antifoam agent comprising a fluorinated polysiloxane dispersed or dissolved in a solvent comprising an aliphatic solvent or a ketone having 5 to 16 carbon atoms (e.g., an aliphatic ketone), the third antifoam agent having a kinematic viscosity in the range of 50 to 500 mm2 / s at 25°C (solvent free). Such antifoam mixtures are disclosed in U.S. Pat. No. 9,3309,480, Loop et al., April 12, 2016.

[0063] Friction modifiers, in the context of automatic transmission lubricants, are materials designed to provide a high and stable coefficient of friction for lubricating clutch plates, typically including mating plates of metal (iron) and non-metallic composition such as cellulose surfaces. Friction modifiers are well known to those skilled in the art. Lists of friction modifiers that may be used are included in U.S. Pat. Nos. 4,792,410, 5,395,539, 5,484,543, and 6,660,695. U.S. Pat. No. 5,110,488 discloses metal salts of fatty acids, particularly zinc salts, that are useful as friction modifiers. The list of friction modifiers that may be used may include borated alkoxylated fatty amines; fatty acid amides; metal salts of fatty acids; fatty epoxides; sulfurized olefins; fatty imidazolines; fatty amines; condensation products of carboxylic acids and polyalkylene polyamines; glycerol esters; metal salts of alkyl salicylates; borated glycerol esters; amine salts of alkyl phosphoric acids; alkoxylated fatty amines; ethoxylated alcohols; oxazolines; imidazolines; hydroxyalkylamides; polyhydroxy tertiary amines; and mixtures of two or more thereof.

[0064] Non-borated fatty epoxides may also be useful as complementary friction modifiers.

[0065] The borated amines that can be used are disclosed in U.S. Patent No. 4,622,158. The borated amine friction modifiers (including borated alkoxylated fatty amines) can be prepared by reacting the boron compounds as described above with the corresponding amines, including simple fatty amines and hydroxy-containing tertiary amines. The amines useful for preparing the borated amines can include commercially available alkoxylated fatty amines known under the trademark "ETHOMEEN" and available from Akzo Nobel, such as bis[2-hydroxyethyl]-cocoamine, polyoxyethylene

[10] cocoamine, bis[2-hydroxyethyl]-soyamine, bis[2-hydroxyethyl]-tallowamine, polyoxyethylene-[5]tallowamine, bis[2-hydroxyethyl]oleylamine, bis[2-hydroxyethyl]-octadecylamine, and polyoxyethylene

[15] -octadecylamine. Such amines are described in U.S. Patent No. 4,741,848.

[0066] Alkoxylated fatty amines and the fatty amines themselves (such as oleylamine) can be useful as friction modifiers. These amines are commercially available.

[0067] Both borated and non-borated fatty acid esters of glycerol can be used as friction modifiers. The borated fatty acid esters of glycerol can be prepared by borating the fatty acid esters of glycerol with a boron source such as boric acid. The fatty acid esters of glycerol themselves can be prepared by a variety of methods well known in the art. Many of these esters, such as glycerol monooleate and glycerol tallowate, are produced on a commercial scale. Commercially available glycerol monooleate can contain a mixture of 45-55% by weight of the monoester and 55-45% by weight of the diester.

[0068] Fatty acids can be used to prepare the glycerol esters described above, which can also be used to prepare their metal salts, amides, and imidazolines, any of which can also be used as friction modifiers. The fatty acids can contain 6 to 24 carbon atoms or 8 to 18 carbon atoms. A useful acid can be oleic acid.

[0069] The amides of fatty acids may be prepared by condensation with ammonia or primary or secondary amines, such as diethylamine and diethanolamine. The fatty imidazolines may include cyclic condensation products of acids with diamines or polyamines, such as polyethylene polyamines. In one embodiment, the friction modifier may be a condensation product of a C8-C24 fatty acid with a polyalkylene polyamine, such as a product of isostearic acid and tetraethylene pentamine. The condensation product of a carboxylic acid with a polyalkylene amine may be an imidazoline or an amide.

[0070] The fatty acids may also be present as their metal salts, for example zinc salts. These zinc salts may be acidic, neutral, or basic (overbased). These salts may be prepared from the reaction of a zinc-containing reagent with a carboxylic acid or its salt. A useful method for preparing these salts is to react zinc oxide with a carboxylic acid. Useful carboxylic acids are those described herein above. Suitable carboxylic acids include those of the formula RCOOH, where R is an aliphatic or alicyclic hydrocarbon radical. Among these are those where R is an aliphatic group, for example, stearyl, oleyl, linoleyl, or palmityl. Zinc salts in which the zinc is present in stoichiometric excess over the amount required to prepare a neutral salt are also suitable. Salts in which the zinc is present in 1.1 to 1.8 times the stoichiometric amount of zinc, for example, 1.3 to 1.6 times the stoichiometric amount, may be used. These zinc carboxylates are known in the art and are described in U.S. Pat. No. 3,367,869. Metal salts may also include calcium salts. Examples can include overbased calcium salts.

[0071] Sulfurized olefins are also well-known commercially available materials used as friction modifiers. Suitable sulfurized olefins are those prepared according to the detailed teachings of U.S. Pat. Nos. 4,957,651 and 4,959,168, which describe a co-sulfurized mixture of two or more reactants selected from the group consisting of at least one fatty acid ester of a polyhydric alcohol, at least one fatty acid, at least one olefin, and at least one fatty acid ester of a monohydric alcohol. The olefin component may be an aliphatic olefin, which will usually contain from 4 to 40 carbon atoms. Mixtures of these olefins are commercially available. Sulfurizing agents useful in the process of the present invention include elemental sulfur, hydrogen sulfide, mixtures of sulfur halides and sodium sulfide, and hydrogen sulfide and sulfur or sulfur dioxide.

[0072] Metal salts of alkyl salicylates include calcium and other salts of long chain (eg, C12-C16) alkyl substituted salicylic acids.

[0073] Amine salts of alkyl phosphates include salts of oleyl and other long chain esters of phosphoric acid and amines, such as tertiary aliphatic primary amines, sold under the trade name Primene™.

[0074] Eighty-five percent phosphoric acid is a suitable material to add to a fully formulated composition to increase frictional properties and may be included at a level of 0.01 to 0.3 percent by weight, for example 0.03 to 0.2 or 0.1 percent, based on the weight of the composition.

[0075] The amount of the additional friction modifier, when present, may be from 0.01 to 10 or 5 weight percent of the lubricating composition, from 0.1 to 2.5 weight percent of the lubricating composition, such as from 0.1 to 2.0, 0.2 to 1.75, 0.3 to 1.5, or 0.4 to 1 percent. However, in some embodiments, the amount of friction modifier is present in an amount less than 0.2 weight percent or less than 0.1 weight percent, such as from 0.01 to 0.1 percent.

[0076] Antioxidants include phenolic antioxidants, which may be hindered phenolic antioxidants, in which one or both of the ortho positions on the phenol ring are occupied by a bulky group, such as t-butyl. The para position may also be occupied by a hydrocarbyl group or a group bridging two aromatic rings. In certain embodiments, the para position is occupied by an ester-containing group, such as, for example, the antioxidant of the formula:

[0077] [ka] In the formula, R 3 is, for example, a hydrocarbyl group such as an alkyl group containing 1 to 18, or 2 to 12, or 2 to 8, or 2 to 6 carbon atoms, and the t-alkyl can be t-butyl. Such antioxidants are described in more detail in U.S. Pat. No. 6,559,105.

[0078] Antioxidants also include aromatic amines. In one embodiment, the aromatic amine antioxidant can include an alkylated diphenylamine, such as nonylated diphenylamine, or a mixture of di- and mono-nonylated diphenylamine.

[0079] Antioxidants also include sulfurized olefins, such as mono- or disulfides or mixtures thereof. These materials generally have sulfide bonds of 1 to 10, e.g., 1 to 4, or 1 or 2 sulfur atoms. Materials that can be sulfurized to form the sulfurized organic compositions of the present invention include oils, fatty acids and esters, olefins and polyolefins made therefrom, terpenes, or Diels-Alder adducts. Details of the preparation of such sulfurized materials can be found in U.S. Pat. Nos. 3,471,404 and 4,191,659.

[0080] Molybdenum compounds also function as antioxidants, and these materials can serve a variety of other functions, such as antiwear and friction modifiers. U.S. Patent No. 4,285,822 discloses a lubricating oil composition containing a molybdenum- and sulfur-containing composition prepared by combining a polar solvent, an acidic molybdenum compound, and an oil-soluble basic nitrogen compound to form a molybdenum-containing complex, and contacting the complex with carbon disulfide to form a molybdenum- and sulfur-containing composition.

[0081] Of course, typical amounts of antioxidants will depend on the particular antioxidant and its individual effectiveness, but exemplary total amounts can be from 0.01 to 5 percent by weight, or from 0.15 to 4.5 percent, or from 0.2 to 4 percent.

[0082] Detergents are typically overbased materials, otherwise called overbased or overbased salts, and are generally homogeneous Newtonian systems with metal content in excess of that which would be present for neutralization according to the stoichiometry of the metal and detergent anion. The amount of excess metal is generally expressed as a metal ratio, i.e., the ratio of total equivalents of metal to equivalents of acidic organic compound. Overbased materials are prepared by reacting an acidic material (such as carbon dioxide) with an acidic organic compound, an inert reaction medium (e.g., mineral oil), a stoichiometric excess of a metal base, and a promoter such as a phenol or alcohol. The acidic organic material will usually have a sufficient number of carbon atoms to provide solubility in oil.

[0083] Overbased detergents may be characterized by their Total Base Number (TBN, ASTM D2896), the amount of strong acid required to neutralize all of the basicity of the material, expressed in mg KOH per gram of sample. Because overbased detergents are typically provided in a form that contains diluent oil, for the purposes of this document, the TBN is recalculated to an oil-free basis by dividing by the percentage of the detergent (as supplied) that is not oil. The TBN of some useful detergents may be 100-800, or 150-750, or 400-700.

[0084] Metal compounds useful for making basic metal salts are generally any Group 1 or Group 2 metal compounds (CAS version of the Periodic Table of Elements). Examples include alkali metals such as sodium, potassium, lithium, copper, magnesium, calcium, barium, zinc, and cadmium. In one embodiment, the metal is sodium, magnesium, or calcium. The anionic portion of the salt can be a hydroxide, oxide, carbonate, borate, or nitrate.

[0085] In one embodiment, the lubricant may contain an overbased sulfonate detergent. Suitable sulfonic acids include sulfonic acids and thiosulfonic acids, including mononuclear or polynuclear aromatic or alicyclic compounds. Certain oil-soluble sulfonates may be represented by R2-T-(SO3-)a or R3-(SO3-)b, where a and b are each at least 1, T is a cyclic nucleus such as benzene or toluene, R2 is an aliphatic group such as alkyl, alkenyl, alkoxy, or alkoxyalkyl, (R2)-T typically contains at least 15 carbon atoms in total, and R3 is typically an aliphatic hydrocarbyl group containing at least 15 carbon atoms. The groups T, R2, and R3 may also contain other inorganic or organic substituents. In one embodiment, the sulfonate detergent can be a predominantly linear alkylbenzene sulfonate detergent having a metal ratio of at least 8 as described in U.S. Patent Application No. 2005065045, paragraphs

[0026] -

[0037] .

[0086] Another overbased material is overbased phenate detergents. Phenols useful for making phenate detergents can be represented as (R1)a-Ar-(OH)b, where R1 is an aliphatic hydrocarbyl group of 4 to 400, or 6 to 80, or 6 to 30, or 8 to 25, or 8 to 15 carbon atoms, Ar is an aromatic group such as benzene, toluene or naphthalene, a and b are each at least 1, and the sum of a and b is the maximum number of replaceable hydrogens on the aromatic nucleus of Ar, such as 1 to 4 or 1 to 2. Phenate detergents may also be provided as sulfur bridged species.

[0087] In one embodiment, the overbased material is an overbased saligenin detergent. Overbased saligenin detergents are generally overbased magnesium salts based on saligenin derivatives. Saligenin detergents are disclosed in more detail in U.S. Pat. No. 6,310,009, with particular reference to their method of synthesis (column 8 and Example 1).

[0088] Salixarate derivatives and their preparation methods are described in more detail in U.S. Pat. No. 6,200,936 and WO 01 / 56968. Salixarate derivatives are believed to have a predominantly linear structure rather than a macrocyclic structure, but both structures are intended to be included in the term "salixarate." Overbased glyoxylic detergents and their preparation methods are disclosed in more detail in U.S. Pat. No. 6,310,011 and references cited therein. Overbased detergents can also be overbased salicylates, such as alkali metal or alkaline earth metal salts of substituted salicylic acids. Overbased salicylate detergents and their preparation methods are disclosed in U.S. Pat. Nos. 4,719,023 and 3,372,116. Other overbased detergents can include overbased detergents having a Mannich base structure, as disclosed in U.S. Pat. No. 6,569,818.

[0089] In certain embodiments, the hydrocarbyl substituents on the hydroxy-substituted aromatic rings in the detergent (e.g., phenates, saligenins, salixarates, glyoxylates, or salicylates) are free or substantially free of C12 aliphatic hydrocarbyl groups (e.g., less than 1%, 0.1%, or 0.01% by weight of the substituents are C12 aliphatic hydrocarbyl groups). In some embodiments, such hydrocarbyl substituents contain at least 14 or at least 18 carbon atoms.

[0090] The amount of overbased detergent in the formulation of the present technology, when present, can typically be at least 0.6 weight percent, or 0.7-5 weight percent, or 1-3 weight percent, or 0.05-0.55 weight percent on an oil-free basis. There can be a single detergent or multiple detergents. Stated alternatively, the amount of overbased calcium detergent can be 110-550 parts per million by weight, or an amount suitable to deliver 175 or 400 or 175-300 ppm.

[0091] Corrosion inhibitors often refer to copper (or "yellow metal") corrosion inhibitors. Such materials include triazole compounds, such as tolyltriazole, derivatives of tolyltriazole, imidazoline compounds, thiadiazoles, carboxylic acids and their salts or esters, and alkanolamines.

[0092] Antiwear agents may also be included in addition to or in addition to the phosphorus esters detailed above. Examples include phosphorus-containing antiwear / extreme pressure agents, such as phosphate esters and their salts, phosphorus-containing carboxylic acids, esters, ethers, and amides, and phosphites. In certain embodiments, the phosphorus antiwear agent may be present in an amount to deliver 0.01 to 0.2, or 0.015 to 0.15, or 0.02 to 0.1, or 0.025 to 0.08 percent phosphorus. Non-phosphorus-containing antiwear agents include borate esters (including borated epoxides), dithiocarbamate compounds, molybdenum-containing compounds, and sulfurized olefins.

[0093] Extreme pressure (EP) agents include some of the materials listed elsewhere herein, as well as other sulfur and chlorosulfur-containing EP agents, chlorinated hydrocarbon EP agents, and phosphorus EP agents. Examples of such EP agents include chlorinated waxes; sulfurized olefins (e.g., sulfurized isobutylene); organic sulfides and polysulfides, such as dibenzyl disulfide, bis-(chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurized methyl ester of oleic acid, sulfurized alkylphenols, sulfurized dipentene, sulfurized terpene, and sulfurized Diels-Alder adducts; phosphorus sulfurized hydrocarbons, such as the reaction products of phosphorus sulfide with turpentine or methyl oleate; phosphites such as dihydrocarbon and trihydrocarbon phosphites, such as dibutyl phosphite. , diheptyl phosphite, dicyclohexyl phosphite, pentyl phenyl phosphite; dipentyl phenyl phosphite, tridecyl phosphite, distearyl phosphite, and polypropylene substituted phenol phosphite; metal thiocarbamates, such as zinc dioctyldithiocarbamate; amine salts or derivatives of alkyl and dialkyl phosphoric acids, including, for example, the amine salts of the reaction products of dialkyl dithiophosphoric acids with propylene oxide (as described in U.S. Pat. No. 3,197,405), which have subsequently been further reacted with P2O5, and mixtures thereof.

[0094] Seal swell agents include oil soluble esters and oil soluble sulfones, sulfolanes such as isodecyl sulfolane, benzyl esters, lactones, nitriles, phenolic materials, or phthalate esters.

[0095] As used herein, the term "condensation product" is intended to encompass esters, amides, imides, and other such materials that may be prepared by the condensation reaction of an acid or a reactive equivalent of an acid (e.g., an acid halide, anhydride, or ester) with an alcohol or an amine, regardless of whether a condensation reaction is actually carried out to lead directly to the product. Thus, for example, a particular ester may be prepared by a transesterification reaction rather than directly by a condensation reaction. The resulting product would still be considered a condensation product.

[0096] The amount of each chemical component listed is exclusive of any solvent or diluent oil that may be customarily present in commercially available materials, i.e., expressed on an active chemical basis, unless otherwise indicated. However, unless otherwise indicated, each chemical or composition referred to herein should be construed as being a commercial grade material that may contain isomers, by-products, derivatives, and other such materials normally understood to be present in commercial grades.

[0097] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include: Hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic, aliphatic, and alicyclic substituted aromatic substituents, as well as cyclic substituents in which the ring is completed through another portion of the molecule (e.g., two substituents taken together form a ring); Substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy); Hetero substituents, i.e., in the context of the present invention, include those that have a predominantly hydrocarbon character but contain other than carbon in a ring or chain otherwise composed of carbon atoms, and include substituents such as pyridyl, furyl, thienyl, and imidazolyl.Heteroatoms include sulfur, oxygen, and nitrogen.In general, there will be no more than two, or no more than one non-hydrocarbon substituent for every 10 carbon atoms in the hydrocarbyl group, and alternatively, there may be no non-hydrocarbon substituents in the hydrocarbyl group.

[0098] It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may differ from those initially added. For example, metal ions (e.g., of a detergent) may migrate to other acidic or anionic sites of other molecules. The products formed thereby may not be easily explained, including the products formed when the composition of the present invention is used in its intended application. Nevertheless, all such modifications and reaction products are included within the scope of the present invention. The present invention encompasses the composition prepared by mixing the components described above.

[0099] The invention provides a method of minimizing conductive deposits in a conductive device by lubricating the device with a lubricant described herein (i.e., a lubricant containing, in some cases, an oil of lubricating viscosity and 0.3 to 1 weight percent of a borate ester, or in other cases, 0.3 to 1 weight percent of a borate ester and 0.01 to 1.0 weight percent of a thiadiazole compound). In one embodiment, the conductive device can be, for example, an electric motor.

[0100] In certain embodiments, the electrically conductive device may be an electric motor in a driveline of an electric vehicle. A method of lubricating such an electric motor may involve operating the driveline device under normal operating conditions and using a lubricant to lubricate or cool the electric motor. The lubricant may be dripped onto a motor coil of the electric motor. In embodiments, the lubricant may be sprayed onto the motor coil. The coil may be immersed in the lubricant.

[0101] In one embodiment, the electric motor may be part of a transmission in a motor vehicle, which may be useful where the automatic transmission contains bearings, such as needle bearings, that are lubricated by the lubricant composition.

[0102] In another embodiment, the motor may be part of a driveline device having at least two gears, such as in a vehicle gearbox (e.g., manual transmission), or an axle or differential, or other driveline power transmission device. The driveline device may also include bearings. The rolling elements of the bearings may be cylindrical or ball in design. The lubricated gears may include amvoid, or spiral bevel, or more commonly, hypoid gears, such as those in drive axles. The gear ratio of the axle may be 2:1 to 8:1, and the diameter of the ring gear may be about 13 to 64 cm. The axle may incorporate an open differential or some type of traction enabling device. The axle may be part of a drivetrain with one or more drive axles, such as a tandem or tridem design, and the axles may be coupled together with a power splitter. Applications for these axles include light, medium, and heavy vehicles (e.g., vocational or linehaul service), and may be used on highways or on the road. The axles may be from a conventional petroleum-powered vehicle, an electric drive vehicle, or a hybrid of both. An electric axle may combine an electric motor, power electronics, and transmission in a unit that directly powers the vehicle's axles.

[0103] The lubricant should be able to lubricate other components of the driveline device and therefore meet other aspects expected in the normal operation of the driveline device.

[0104] In addition, the methods provided herein can maintain an abrasion rating of greater than 10 on electrically conductive devices at 150° C. according to ASTM D5182.

[0105] The advantages and uses of the disclosed technology may be better understood with reference to the following examples. EXAMPLES

[0106] Two commercially available lubricants were evaluated in the new conductive layer deposit test: Lubricant 1 is commercially available as Evogen™ 5191SA, and Lubricant 2 is ZF Lifeguard 8. Note that Lubricant 1 contains significantly reduced levels of sulfur compared to Lubricant 2 (see Table 1).

[0107] For each fluid, ten copper printed circuit boards (PCBs) were arranged in two separate stacks, five in the oil solution and five in the vapor space. The tested fluids were contained in a sealed vented container heated to 150° C. The fluids were subjected to an electric current of 5 V. Conductivity (S) measurements were recorded over time for both the solution and vapor phase printed circuit boards. The results of the energized board conductivity versus time are shown in Tables 1 and 2. Conductivity values ​​are reported in microsiemens (μS).

[0108] [Table 1]

[0109] [Table 2]

[0110] Lubricant 1 does not form conductive layer deposits as the conductivity values ​​in both the solution and gas phases do not change appreciably. Lubricant 2 showed the formation of conductive deposits in both the solution and gas phases simultaneously.

[0111] Lubricant 1, in both solution and vapor phase, exhibits no visible deposits formed on the substrate at end of test (EOT). The vapor phase PCB substrate has some darkening present. At the end of test, the test conductivity measurements on all substrates are below measurable values.

[0112] Lubricant 2 has visible deposits in both the solution and vapor phases. All of the test-finished boards have conductivities greater than that of a virgin PCB.

[0113] Lubricant 3 is a fully formulated automatic transmission fluid prepared according to the formulation in Table 3 below. The formulation contained in Lubricant 3 was optimized to provide excellent wear protection in the FZG test for load carrying capacity while maintaining low corrosion of copper in traditional solution phase testing. (See performance results in Table 4) When Lubricant 3 was tested to determine its performance in the conductive layer deposit test, failing results were observed.

[0114] [Table 3]

[0115] Two components were selected as potentially detrimental to this test due to the presence of sulfur. One was an alkylated dimercaptothiadiazole (S-1), which typically functions as a corrosion inhibitor and also has the potential to provide EP / antiwear performance. The second was a post-treated dispersant (S-2) that also contained a dimercaptothiadiazole. A description of this dispersant can be found in U.S. Pat. No. 4,140,643. Attempts were made to reduce the levels of one or both of these materials in Lubricants 4 and 5 to improve the results obtained in the conductive layer deposit test. However, these were unsuccessful. Surprisingly, however, the addition of an increased treat rate of a borate ester (Lubricant 6) allowed formulations still containing these components to pass the conductive layer deposit test.

[0116] [Table 4]

[0117] Each of the documents mentioned above is incorporated herein by reference, including any prior application to which priority is claimed, whether or not specifically listed above. The reference of any document is not an admission that such document qualifies as prior art or constitutes the general knowledge of the skilled artisan in any jurisdiction. Except in the examples or where otherwise expressly indicated, all quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, should be understood as being optionally modified by the word "about". It should be understood that the upper and lower limits of amounts, ranges, and ratios described herein can be independently combined. Similarly, the ranges and amounts for each element of the present invention can be used together with ranges or amounts for any of the other elements.

[0118] As used herein, the transitional term "comprising," which is synonymous with "including," "containing," or "characterized by," is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. However, in each occurrence of "comprising" herein, the term is also intended to encompass, as alternative embodiments, the phrases "consisting essentially of" and "consisting of," where "consisting" excludes any unspecified elements or steps, and "consisting essentially of" permits the inclusion of additional, unrecited elements or steps that do not materially affect the essential or basic and novel characteristics of the composition or method under consideration. The phrases "consisting of" or "consisting essentially of," when applied to an element of a claim, are intended to limit all species of the type represented by that element, notwithstanding the absence of "comprising" anywhere in the claim.

[0119] While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention, which in this regard should be limited only by the claims that follow.

Claims

1. 1. A method for minimizing conductive deposits in an electrically conductive device, the method comprising: applying to the device a lubricant comprising an oil of lubricating viscosity and 0.2 to 1.1 weight percent of a borate ester; and applying an electric current to the device.

2. The method of claim 1 , wherein the lubricant further comprises 0.01 to 1 weight percent of a thiadiazole compound.

3. 10. The method of claim 1, wherein the method maintains an abrasion rating of greater than 10 at 150° C. according to ASTM D5182.

4. The method of claim 1 , wherein the borate ester comprises formula (I): 【Chemistry 11】

5. 2. The method of claim 1 , wherein the borate ester comprises the formula (II): 【Chemistry 12】

6. 2. The method of claim 1 , wherein the borate ester comprises the formula (III): 【Chemistry 13】

7. 2. The method of claim 1 , wherein the borate ester comprises the formula (IV): 【Chemistry 14】

8. 2. The method of claim 1 , wherein the borate ester comprises the formula (V): 【Chemistry 15】

9. 2. The method of claim 1 , wherein the borate ester comprises the formula (VI): 【Chemistry 16】

10. The method of any one of claims 4 to 9, wherein each R is independently 4 to 18.

11. 10. The method of any one of claims 4 to 9, wherein each R, individually, R is 6 to 12.

12. 10. The method of any one of claims 4 to 9, wherein each R, individually, R is 9 to 18.

13. 10. The method of any one of claims 4 to 9, wherein each R, individually, R is 10 to 18.

14. 10. The method of any one of claims 4 to 9, wherein each R, individually, R is 12 to 18.

15. 10. The method of any one of claims 4 to 9, wherein each R, individually, R is 14 to 18.

16. 10. The method of any one of claims 4 to 9, wherein each R is individually selected from isopropyl, n-butyl, isobutyl, amyl, 2-pentenyl, 4-methyl-2-pentyl, 2-ethylhexyl, heptyl, isooctyl, nonyl, decyl, undecyl, dodecenyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, and mixtures thereof.

17. The method of any one of claims 1 to 16, wherein the borate ester comprises tripropyl borate.

18. The method of any one of claims 1 to 17, wherein the borate ester comprises tributyl borate.

19. The method of any one of claims 1 to 18, wherein the borate ester comprises tripentyl borate.

20. The method of any one of claims 1 to 19, wherein the borate ester comprises trihexylborate.

21. The method of any one of claims 1 to 20, wherein the borate ester comprises triheptyl borate.

22. The method of any one of claims 1 to 21, wherein the borate ester comprises trioctyl borate.

23. 23. The method of any one of claims 1 to 22, wherein the borate ester comprises trinonyl borate.

24. The method of any one of claims 1 to 23, wherein the borate ester comprises tridecyl borate.

25. The method of any one of claims 1 to 24, wherein the borate ester comprises tri-2-ethylhexyl borate.

26. The method of any one of claims 1 to 25, wherein the borate ester is present in the lubricant at 0.25 to 1.1 weight percent.

27. The method of any one of the preceding claims, wherein the borate ester is present in the lubricant at 0.25 to 1.1 weight percent.

28. The method of any one of the preceding claims, wherein the borate ester is present in the lubricant at 0.3 to 1.1 weight percent.

29. The method of any one of claims 1 to 28, wherein the borate ester is present in the lubricant at 0.4 to 1 weight percent.

30. The method of any one of claims 1 to 29, wherein the borate ester is present in the lubricant at 0.45 to 1 weight percent.

31. The method of any one of claims 1 to 30, wherein the borate ester is present in the lubricant at 0.2 to 1 weight percent.

32. The method of any one of claims 1 to 31, wherein the borate ester is present in the lubricant at 0.25 to 1 weight percent.

33. The method of any one of claims 1 to 32, wherein the borate ester is present in the lubricant at 0.3 to 1 weight percent.

34. The method of any one of claims 1 to 33, wherein the borate ester is present in the lubricant at 0.3 to 0.8 weight percent.

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