CN111108182B - Lubricating composition for hybrid electric vehicle transmission - Google Patents

Abstract

The disclosed technology relates to a lubricant composition for use in an automatic transmission of a hybrid electric vehicle, the lubricant composition containing an oil of lubricating viscosity, at least one borate ester, and at least one phosphorus-containing compound.

Description

Lubricating composition for hybrid electric vehicle transmission

Background

The disclosed technology relates to a lubricant composition for use in an automatic transmission of a hybrid electric vehicle containing an oil of lubricating viscosity, at least one borate ester, and at least one phosphorus-containing compound.

Driveline transmissions, and Automatic Transmission Fluid (ATF) in particular, present extremely challenging technical problems and solutions to meet the many and often conflicting lubrication and power transfer requirements of modern automatic transmissions, including continuously variable transmissions of various types. A number of additive components are typically included in ATFs to provide performance characteristics such as lubrication, dispersancy, friction control (for clutches), antiwear durability (e.g., gear wear) and pump durability, fuel economy, anti-shudder performance, anti-corrosion and anti-oxidation performance. However, during the period of use, the additive components are consumed, which may detrimentally damage the transmission.

In addition to the normal problems, transmissions in electric vehicles (typically automatic transmissions) present a unique set of problems. For example, lubricants used in transmissions in electric vehicles may come into contact with electrically powered components in the vehicle (such as parts of an electric motor). Thus, one desirable attribute of such lubricants is relatively low electrical conductivity to avoid potential current leakage and casing resistance, particularly as the lubricating oil ages. However, the lubricant must still provide adequate lubrication including, for example, dispersancy, cleanliness, antiwear and anti-corrosion. Also, it is desirable to maintain a low viscosity fluid for such vehicles to improve vehicle efficiency. Therefore, new transmission oil is required to achieve these often competing results.

Disclosure of Invention

The disclosed technology provides a lubricant composition having a kinematic viscosity at 40 ℃ of from 8cSt to 18cSt, the lubricant composition comprising an oil of lubricating viscosity, from 0.3 to 2.0 wt% of at least one borate ester, and at least one phosphorus-containing compound present in an amount to deliver from 100 to 450ppm of phosphorus to the lubricating composition.

In one embodiment, the boronic ester may be a compound of formula I,

wherein each R is independently C ₃To C₁₂An alkyl group.

In some embodiments, the phosphorus-containing compound may include at least one of: (1) phosphorous acid C_3-8Hydrocarbyl esters, (2) phosphite compositions comprising the reaction product of monomeric phosphorous acid or esters thereof with at least two alkylene glycols, or (3) mixtures of (1) and (2).

In embodiments, the lubricant composition may additionally include 0.01 to 1.0 weight percent of an ester of (1) a polyol and 2) an aliphatic carboxylic acid containing from about 12 to about 24 carbon atoms, for example, glycerol monooleate.

In further embodiments, the lubricant composition may further comprise 0.1 to 3.0 wt.% of an ester of (1) an alcohol and 2) an aliphatic carboxylic acid containing from about 4 to about 8 carbon atoms, e.g., an adipate ester.

In yet further embodiments, the lubricant composition may contain 0.01 wt% to 0.5 wt% dimercaptothiadiazole or derivative thereof.

The lubricant composition may also contain 0.1 wt% to 5 wt% of a poly (meth) acrylate polymer viscosity modifier.

In another embodiment, the composition may contain a total amount of dispersant of 1 wt% or less.

In some embodiments, the lubricant composition can further include 0.05 wt% to 1.0 wt% phosphorous acid C₁₂To C₂₄Hydrocarbyl esters.

The lubricant composition may further include 0.01 wt% to 1.0 wt% of C _12-24The epoxide is borated.

The lubricant composition may further comprise 0.1 wt% to 3.0 wt% of a mixture of at least two antioxidants selected from the group consisting of hindered phenols, aryl amines, and sulfur-containing antioxidants.

The lubricant composition may be employed in a method of lubricating an automatic transmission by supplying the lubricant composition into the automatic transmission and operating the automatic transmission.

Detailed Description

Various preferred features and embodiments are described below by way of non-limiting illustration.

One aspect of the present technology is a lubricant composition. The lubricant composition may be used to provide lubrication to an automatic transmission of a hybrid electric vehicle. The composition may include, among other things, an oil of lubricating viscosity, at least one borate, and at least one phosphorus-containing compound in an amount sufficient to deliver 100 to 450ppm of phosphorus to the lubricating composition.

Oil of lubricating viscosity

Oils of lubricating viscosity may be defined as specified in the American Petroleum Institute (API) guide for Base Oil Interchangeability (Base Oil interchange Guidelines). The five base oil groups are as follows: group I (sulfur content >0.03 wt%, and/or saturates <90 wt%, viscosity index 80-120); group II (sulfur content not more than 0.03 wt%, and saturates not less than 90 wt%, viscosity index 80-120); group III (sulfur content not more than 0.03 wt%, saturates not less than 90 wt%, viscosity index not less than 120); group IV (all Polyalphaolefins (PAO)); and group V (all other base oils not included in groups I, II, III or IV). The oil of lubricating viscosity may include, for example, an API group I, group II, group III, group IV, group V oil, or mixtures thereof.

Typically, the oil of lubricating viscosity is an API group I, group II, group III, group IV oil or mixtures thereof. Alternatively, the oil of lubricating viscosity may be an API group II, group III or group IV oil or mixtures thereof.

In one embodiment, the oil of lubricating viscosity may be prepared by a fischer-tropsch gas-liquid synthesis procedure, as well as other gas-liquid oils.

In one embodiment, the oil of lubricating viscosity may be an API group IV oil. The amount of group IV oil may be from 0 wt% to 20 wt%, or from 0.1 wt% to 20 wt%, or from 1 wt% to 15 wt%, or from 5 wt% to 10 wt% of the lubricating composition.

The amount of oil of lubricating viscosity present is typically the balance remaining after subtracting the sum of the amounts of the performance additives of the present invention from 100 wt%.

The lubricating composition may be in the form of a concentrate and/or a fully formulated lubricant. If the performance additive of the present invention is in the form of a concentrate (which may be combined with additional oil to form, in whole or in part, a finished lubricant), the ratio of performance additive to oil of lubricating viscosity and/or diluent oil includes the ranges 1:99 to 99:1 (by weight) or 80:20 to 10:90 (by weight).

Boron-containing compounds

The lubricant composition may contain a boron-containing compound in an amount sufficient to provide from about 75ppm to about 500ppm of boron to the lubricant composition, or from about 85 to about 450ppm or from about 95 to about 350ppm of boron to the lubricant composition, or from about 100 to about 400ppm of boron.

Boron can be delivered by various types of boron-containing compounds.

The boron-containing compound may be a dispersant post-treated with a boron source. Such dispersants are typically obtained by reacting a carboxylic acid (e.g., succinimide), amine, or mannich dispersant with a boron compound reagent (e.g., boric acid) (to produce a "borated dispersant"). Dispersants and methods for their production are well known in the art. The borated dispersant may additionally be functionalized with a sulfur or phosphorus moiety. The dispersant component of the borated dispersant may be a mixture of a plurality of dispersants (which may be of different types); optionally, at least one can be a succinimide dispersant. In one embodiment, the borated dispersant may be a borated polyisobutylene succinimide dispersant wherein the polyisobutylene moiety thereof may have a number average molecular weight of 750 to 2200, or 750 to 1350, or 750 to 1150. The one or more borated dispersants may be prepared in a manner having an N: CO ratio of from 0.9:1 to 1.6:1, or from 0.95:1 to 1.5:1, or from 1:1 to 1.4: 1. The amount of borated dispersant in the composition may be, for example, from 0.05 to 2.0 weight percent. In other embodiments, the amount is 0.1 to 1.0%, or 0.15 to 0.75% of the final blended fluid formulation. In the concentrate, the amount will be proportionally higher.

The boron-containing compound may include boron-containing friction modifiers such as borated fatty epoxides, borated glycerol esters, and borated alkoxylated fatty amines.

The boron-containing compound may also include borated detergents. Borated detergents may include, for example, overbased borated materials, as described in U.S. Pat. nos. 5,403,501 and 4,792,410.

The boron-containing compound may also include borate esters. The borate ester may be a compound represented by one or more of the following formulae:

wherein each R may independently be a hydrocarbyl group as that term is defined herein, and any two adjacent R groups may together form a cyclic group. Mixtures of two or more of the foregoing may be used. The total number of carbon atoms in each of the R groups in each formula should be sufficient to render the compound soluble in an oil of lubricating viscosity. Typically, the total number of carbon atoms in the R group is at least about 3, and in one embodiment at least about 5, and in one embodiment at least about 8. There is no limitation on the total number of carbon atoms required in the R group, but a practical upper limit is about 400 or about 500 carbon atoms.

In embodiments, each R may independently be a hydrocarbyl group containing 1 to 14, or 2 to 13, or even 3 to 10 or 12 carbon atoms, provided that the total number of carbon atoms in all R is 3 or more, preferably 4 or more, and even more preferably 6 or more. In some embodiments, each R independently can be C ₃To C₂₂Or C₃To C₁₈Or C₃To C₁₂An alkyl group. Examples of useful R groups include isopropyl, n-butyl, isobutyl, pentyl, 4-methyl-2-pentyl, 2-ethyl-1-hexyl, isooctyl, decyl, dodecyl, 2-propylheptyl, tetradecyl, 2-pentenyl, dodecenyl, phenyl, naphthyl, alkylphenyl and the like.

Suitable examples of borate esters include, for example, tripropyl borate, tributyl borate, tripentyl borate, trihexyl borate, triheptyl borate, trioctyl borate, trinonyl borate, and tridecyl borate. Examples of other borate esters may include, for example, compounds of formula I wherein each R is independently C₃To C₂₂Or C₃To C₁₈Or C₃To C₁₂Alkyl radicals, such as tri-2-ethylhexyl borate, tris (2-propylheptyl) borate, and mixtures thereof. In one embodiment, the borate ester may be C₈Boric acid ester or C₁₀A borate ester. In one embodiment, the borate ester may be tris (2-propylheptyl) borate. In some embodiments, the borate ester may be tri-2-ethylhexyl borate.

In one embodiment, the borated ester may be represented by formula B (OC)₅H₁₁)₃Or B (OC)₄H₉)₃And (4) showing. In one embodiment, the borated ester can be tri-n-butyl borate.

In one embodiment, the borated ester may be a phenolic compound represented by the formula

Wherein in formula VII: r is₁、R₂、R₃And R₄Independently a hydrocarbyl group having from 1 to about 12 carbon atoms; and R is₅And R₆Independently an alkylene group having from 1 to about 6 carbon atoms, and in one embodiment from about 2 to about 4 carbon atoms, and in one embodiment about 2 or about 3 carbon atoms. In one embodiment, R₁And R₂Independently contain from 1 to about 6 carbon atoms and in one embodiment are each t-butyl. In one embodiment, R₃And R₄Independently a hydrocarbyl group having from about 2 to about 12 carbon atoms, and in one embodiment from about 8 to about 10 carbon atoms. In one embodiment, R₅And R₆Independently is-CH₂CH₂- - (O) - -or- - -CH₂CH₂CH₂--。

In one embodiment, the borated ester may be a compound represented by the formula:

wherein in formula IX, each R is independently hydrogen or a hydrocarbyl group. Each of the hydrocarbyl groups may contain 1 to about 12 carbon atoms, and in one embodiment may contain 1 to about 4 carbon atoms. An example is 2,2' -oxy-bis- (4,4, 6-trimethyl-1, 3, 2-dioxaborole).

The borate ester may be used in the lubricant composition at about 0.2 or 0.3 to about 2.0 wt.%, or in some cases about 0.35 to 2.0 wt.%, and in one embodiment about 0.25 to about 1.0 wt.%, and in one embodiment about 0.25 to about 0.75 wt.%, by weight of the lubricant composition.

Phosphorus-containing compound

The lubricant composition contains at least one phosphorus-containing compound. The phosphorus-containing compound may be an acid, salt or ester. In one embodiment, the phosphorus-containing compound is in the form of a mixture of two or three, or two to four (typically two or three) phosphorus-containing compounds.

In some embodiments, the phosphorus-containing compound is a phosphite. Suitable phosphites include those having at least one hydrocarbyl group with 3 or 4 or more, or 8 or more, or 12 or more carbon atoms. The phosphite may be a mono-, di-or tri-hydrocarbyl substituted phosphite.

In one embodiment, the phosphite is sulfur-free, i.e., the phosphite is not a thiophosphite.

Phosphites may be represented by the formula:

wherein at least one R may be a hydrocarbyl group containing at least 3 carbon atoms and the other R groups may be hydrogen. In one embodiment, two of the R groups are hydrocarbyl groups and the third is hydrogen. In one embodiment, each R group is a hydrocarbyl group, i.e., the phosphite is a trihydrocarbyl-substituted phosphite. The hydrocarbyl group can be an alkyl group, a cycloalkyl group, an aryl group, an acyclic group, or a mixture thereof.

The R hydrocarbyl groups may be linear or branched, typically linear, and may be saturated or unsaturated, typically saturated.

In one embodiment, the phosphorus-containing compound can be phosphorous acid C_3-8Hydrocarbyl esters or mixtures thereof, i.e., wherein each R can independently be hydrogen or a hydrocarbyl group having 3 to 8, or 4 to 6 carbon atoms, typically 4 carbon atoms. Generally, phosphorous acid C_3-8The hydrocarbyl ester comprises dibutyl phosphite. Phosphorous acid C_3-8The hydrocarbyl ester can deliver at least 175ppm, or at least 200ppm of the total amount of phosphorus delivered by the phosphorus-containing compound. Phosphorous acid C_3-8The hydrocarbyl ester may be delivered from the phosphorus-containing compound at least 45 wt%, or 50 wt% to 100 wt%%, or from 50 wt% to 90 wt%, or from 60 wt% to 80 wt% of the total amount of phosphorus.

In one embodiment, the phosphorus-containing compound can be phosphorous acid C_12-22Hydrocarbyl esters or mixtures thereof, i.e., wherein each R can independently be hydrogen or a hydrocarbyl group having 12 to 24, or 14 to 20 carbon atoms, typically 16 to 18 carbon atoms. Generally, phosphorous acid C_12-22The hydrocarbyl ester comprises phosphorous acid C_16-18Hydrocarbyl esters. R is³、R⁴And R⁵Examples of alkyl groups of (a) include octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, octadecenyl, nonadecyl, eicosyl or mixtures thereof. Phosphorous acid C _12-22The hydrocarbyl ester may be present in the lubricant composition in an amount of from about 0.05 wt% to about 1.0 wt% of the lubricant composition, or from about 0.1 wt% to about 0.5 wt% of the lubricant composition.

In some embodiments, the phosphorus-containing compound can include phosphorous acid C_3-8And C₁₂To C₂₄A hydrocarbyl ester.

The phosphorus-containing compound can be a phosphite composition that is the reaction product, e.g., a condensation product, of monomeric phosphorous acid or an ester thereof with at least two alkylene glycols. In one embodiment, the phosphite does not contain zinc.

By "monomeric" phosphorous acid or ester is meant phosphorous acid or ester, typically containing one phosphorus atom, which can be reacted with a diol to form oligomeric, polymeric, or other condensed species. The monomeric phosphorous acid or ester thereof may be phosphorous acid itself (H)₃PO₃) Although monomeric partial esters such as dialkyl phosphites may be used for ease of handling or other reasons. The one or more alkyl groups may be relatively low molecular weight groups having 1 to 6 or 1 to 4 carbon atoms, such as methyl, ethyl, propyl or butyl groups, so that the alcohol produced upon reaction with the alkylene glycol can be easily removed. Exemplary phosphites are dimethyl phosphite; other esters include diethyl phosphite, dipropyl phosphite, and dibutyl phosphite. Sulfur-containing analogs (e.g., thiophosphites) can also be employed. Other esters include trialkyl phosphites. Phosphorous acid dioxane Mixtures of the esters and trialkyl phosphites are also useful. In these materials, as noted above, the alkyl groups can be the same or different and each independently typically has 1 to 6 or 1 to 4 carbon atoms.

The monomeric phosphoric acid or ester will react or condense with at least two alkylene glycols to form a phosphorus-containing compound, which may include a polymeric (or oligomeric) phosphorus ester and optionally a monomeric species. The first alkylene glycol (i) will be a 1, 4-or 1, 5-or 1, 6-alkylene glycol. That is, there will be two hydroxyl groups in a 1,4 or 1,5 or 1,6 relationship to each other, separated by a chain of 4, 5 or 6 carbon atoms respectively. The first hydroxyl group can literally be on 1 carbon atom, that is, on a carbon of the diol, or it can be on a higher numbered carbon atom. For example, it will be apparent to those skilled in the art that the diol may also be a 2, 5-or 2, 6-or 2, 7-diol or a 3, 6-or 3, 7-or 3, 8-diol. The alkylene glycol can be branched (e.g., alkyl substituted) or unbranched, and in one embodiment is unbranched. Unbranched, that is to say, straight-chain diols (. alpha.,. omega. -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-dimethyl-1, 5-pentanediol, 1, 5-hexanediol, 2, 5-hexanediol, and 2, 5-dimethyl-2, 5-hexanediol. Diols having one or more secondary hydroxyl groups (e.g., 2, 5-hexanediol) may be referred to as branched or substituted diols, even though the carbon chain itself may be linear. The position of the hydroxyl groups in the 1,4-, 1,5-, or 1, 6-positions (that is, the positions relative to each other or the literal positions) may help promote oligomerization with the phosphorus species rather than formation of cyclic structures, which would be sterically disadvantageous. In certain embodiments, the first alkylene glycol can be 1, 6-hexanediol.

If desired, the first alkylene dihydroxy compound (diol) may have additional hydroxyl groups, that is, more than two per molecule, or there may be exactly two hydroxyl groups present. In one embodiment, there are exactly two hydroxyl groups per molecule. If more than two hydroxyl groups are present, care should be taken to ensure that there is no excessive cyclization as can interfere with the polymerization reaction if there are less than 4 atoms separating any of the hydroxyl groups. In addition, care should be taken to avoid excessive branching or crosslinking in the product, which can lead to undesirable gel formation. Such problems can be avoided by careful control of the reaction conditions, such as control of the ratio of reagents and their order of addition, performing the reaction under appropriate dilution conditions, and reacting under low acid conditions. These conditions can be determined by one skilled in the art using only routine experimentation.

Phosphorous acid or ester is also reacted with a second alkylene glycol (ii). The second alkylene glycol is an alkyl-substituted 1, 3-propanediol having one or more of its alkyl substituents on one or more of the carbon atoms of the propylene unit, the total number of carbon atoms in the alkyl-substituted 1, 3-propanediol being from 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-propanediol may be represented by the following general formula

Wherein each R group can be the same or different and can be hydrogen or alkyl, provided that at least 1R is alkyl and the total number of carbon atoms in the R group is 2 to 9 or 3 to 9, such that the total carbon atoms in the diol will be 5 to 12 or 6 to 12, respectively, and the same is true for other ranges of total carbon. By analogy with the above-mentioned 1,4-, 1, 5-or 1, 6-diols, reference herein to a 1, 3-diol is intended to mean that the two hydroxyl groups are in a 1,3 relationship to each other, that is, separated by a chain of 3 carbon atoms. Thus, a 1, 3-diol may also be referred to as a 2, 4-or 3, 5-diol. If the 1, 3-diol has one or more secondary hydroxyl groups, such molecules will be considered to be substituted diols. In one embodiment, the number of alkyl substituents is 2 and the total number of carbon atoms in the molecule is 9. Suitable substituents may include, for example, methyl, ethyl, propyl and butyl (among the various possible isomers thereof).

Examples of the second alkylene glycol may include 2, 2-dimethyl-1, 3-propanediol, 2-ethyl-2-butylpropan-1, 3-diol, 2-ethylhexane-1, 3-diol, 2-dibutylpropan-1, 3-diol, 2-diisobutylpropane-1, 3-diol, 2-methyl-2-propylpropan-1, 3-diol, 2-propyl-propan-1, 3-diol, 2-butylpropan-1, 3-diol, 2-pentylpropan-1, 3-diol, 2-methyl-2-propylpropan-1, 3-diol, 2-diethylpropan-1, 3-diol, 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 for clarity, some of the foregoing nomenclature emphasizes the propane-1, 3-diol structure of the molecule. For example, 2-pentylpropane-1, 3-diol may also be designated 2-hydroxymethylheptan-1-ol, but the latter designation does not so clearly illustrate the 1, 3-nature of the diol.

The ratio of the relative molar amounts of the first alkylene glycol (i) and the second alkylene glycol (ii) may be from 30:70 to 65:35, or alternatively from 35:65 to 60:40, or from 40:60 to 50:50, or from 40:60 to 45: 55. If the ratio is less than about 30:70, the resulting product may not fully exhibit the benefits of the disclosed technology, and if the ratio is greater than about 65:35, its compatibility with other components in the lubricant formulation may be reduced.

The ratio of the relative molar amount of monomeric phosphorous acid or ester thereof (a) to the total molar amount of alkylene glycol (b) may be from 0.9:1.1 to 1.1:0.9, or from 0.95:1.05 to 1.05:0.95, or from 0.98:1.02 to 1.02:0.98, or about 1: 1. Reactions conducted at about equimolar ratios will tend to promote oligomer formation or polymer formation. The exact 1:1 ratio theoretically can lead to very long chain formation and thus to very high molecular weights. In practice, however, this is not generally achievable, as competing reactions and reaction imperfections will provide a material with a lower degree of polymerization, and some portion of the material will be in the form of cyclic monomers.

The reaction product will typically comprise a mixture of individual species, including some oligomeric or polymeric species as well as cyclic monomeric species. The cyclic monomer species may contain 1 phosphorus atom and one alkylene group derived primarily from the 1, 3-diol (ii) because the 1, 3-diol can participate in the formation of oligomeric or cyclic esters. The oligomeric or polymeric species may typically contain from 2 or 3 to 20 phosphorus atoms, or alternatively from 5 to 10 phosphorus atoms, which are linked together by alkylene groups derived from diols (i) and (ii), and may exhibit relatively preferential incorporation of 1,4-, 1, 5-or 1, 6-diols, which are not readily cyclized with phosphorus to form cyclic monomeric species.

The product can be a mixture of substances that can be represented by the structure shown below:

(oligomeric substance)

Adding

(Cyclic monomer)

Where x and y represent the relative amounts of the two diols incorporated into the oligomer. The structures shown are not intended to indicate that the polymer must be a block polymer, as the structures indicated by the x and y brackets may be more or less randomly distributed, affected by or dependent on the availability of the various glycol reactants. Each X is independently a terminal group which may be, for example, an alkyl group (such as methyl) or hydrogen or a diol-derived moiety which may terminate in an OH group. In the above scheme, for illustration purposes only, diene (i) is selected to be 1, 6-hexanediol and diene (ii) is selected to be 2-butyl-2-ethyl-1, 3-propanediol. Corresponding structures and mixtures will be formed using different diols (i) and (ii).

The relative amounts of oligomeric species and cyclic monomeric species in the reaction mixture will depend to some extent on the particular diol and reaction conditions selected. For the reaction product prepared from 1, 6-hexanediol and 2-butyl-2-ethyl-1, 3-propanediol, as shown by the structure above, the amount of oligomerization product can be approximated as shown in the following table:

mol% of 1, 6-diol	30	40	50	60	65
						wt% oligomer	52	58	62	70	71

And the amount of cyclic monomer can be 100% minus the percentage of oligomer. It is also useful to prepare mixtures of oligomers and cyclic monomers having the above weight percentages regardless of the particular diol employed. In certain embodiments, 55 to 60 weight percent of the product is in oligomeric form and 45 to 40 percent is in cyclic monomeric form. In some embodiments, the relative amount of cyclic monomeric species to oligomeric species is from 1:3 to 1:1, or alternatively, from 1:3 to 1:0.8, by weight.

The condensation reaction between the phosphoric acid or ester and the diol can be achieved by mixing the reagents and heating until the reaction is substantially complete. Typically, the first and second alkylene glycols can be mixed with the phosphorus compound at the same time or nearly the same time (that is, typically before the reaction with one of the alkylene glycols is complete). Small amounts of basic materials, such as sodium methoxide, may also be present. If methyl esters of phosphorous acid are used as reagents, substantial completion of the reaction may correspond to precipitation of methanol from the reaction mixture and cessation of distillation. Suitable temperatures include temperatures in the range of 100 to 140 ℃, such as 110 to 130 ℃ or 115 to 120 ℃. If reaction temperatures in excess of about 140 ℃ are employed, there is a risk that the desired product may not be formed in useful yields or useful purities because competing reactions may occur. The reaction time can typically be as long as 12 hours, depending on the temperature, applied pressure (if any), stirring, and other variables. In some cases, a reaction time of 2 to 8 hours or 4 to 6 hours may be suitable.

Other monomers may be included in the reaction mixture if desired. It is sometimes considered beneficial to include a polycarboxylic acid such as a dicarboxylic acid. For example, inclusion of relatively small amounts of tartaric acid or citric acid can provide a product with useful properties. The amount of polyacid or diacid can be an amount suitable for incorporating at least 1 or about 1 polycarboxylic or dicarboxylic acid monomer unit per product oligomer molecule. In practice the amount of polyacid or diacid added to the reaction mixture may be higher than this amount. Without intending to be bound by any theory, it is believed that when tartaric acid is present in small amounts, it may be incorporated as a terminal unit of the polymer, and may condense with the OH group of the alkylene glycol through an ester bond. Such materials may exhibit good performance in terms of wear protection and corrosion inhibition as well as sealing performance. Suitable polyacids (or esters or anhydrides thereof) include maleic acid, fumaric acid, tartaric acid, citric acid, phthalic acid, terephthalic acid, malonic acid (e.g., esters), succinic acid, malic acid, adipic acid, oxalic acid, sebacic acid, dodecanedioic acid, glutaric acid, and glutamic acid. Another class of monomers that may be included are monocarboxylic acids containing reactive hydroxyl groups or reactive equivalents of such materials, such as anhydrides, esters or lactones. Examples include glyoxylic acid, caprolactone, valerolactone and hydroxystearic acid.

The amount of the above-described phosphite product used in the lubricant may be an amount sufficient to provide 0.01 to 0.3 or 0.1 wt% phosphorus, or in other embodiments, 0.02 to 0.07 wt% or 0.025 to 0.05 wt% phosphorus to the composition. The actual amount of product corresponding to these amounts of phosphorus will, of course, depend on its phosphorus content. Suitable amounts of the ester product in the lubricant composition may be from 0.01 to 1.0 wt.%, or from 0.02 to 0.5 wt.%, or from 0.03 to 0.30 wt.%, or even from 0.05 to 0.25 wt.%.

While each of the above-described phosphorus-containing compounds may be present in the lubricant composition alone, the lubricant composition may also include twoA mixture of one or more. In some embodiments, the phosphorus-containing compound can include phosphorous acid C_3-8Hydrocarbyl esters and phosphite products. In some embodiments, the phosphorus-containing compound can include phosphorous acid C_3-8Alkyl esters, phosphorous acid C₁₂To C₂₄Each of the hydrocarbyl ester and the phosphite product. In either case, the phosphorus-containing compound should be present in an amount to deliver 100 to 450ppm of phosphorus to the lubricant composition. In some embodiments, the at least one phosphorus-containing compound may be present in an amount to deliver 125 to 425ppm phosphorus or 150 to 400ppm phosphorus to the lubricant composition.

The ratio of the phosphorus level in the phosphite to the boron level in the borate should be greater than 0.7, or greater than 0.8, or greater than 0.9 or even greater than 1.0. For example, the ratio may be 0.7 to 5, or 0.8 to 4, or 0.9 to 3, or 1.0 to 2.

Other additives

In addition to the borate ester and the phosphorus-containing compound, the lubricant composition may contain additional additives.

In one embodiment, the lubricant composition may include an ester of a polyol and an aliphatic carboxylic acid having 12 to 24 carbon atoms.

Polyols include diols, triols and alcohols having a higher number of alcoholic OH groups. The polyhydric alcohol comprises ethylene glycol, including diethylene glycol, triethylene glycol and tetraethylene glycol; propylene glycol including dipropylene glycol, tripropylene glycol and tetrapropylene glycol; glycerol; butanediol; hexanediol; sorbitol; arabitol; mannitol; sucrose; fructose; glucose; cyclohexanediol; erythritol; and pentaerythritol, including dipentaerythritol and tripentaerythritol; preferably diethylene glycol, triethylene glycol, glycerol, sorbitol, pentaerythritol and dipentaerythritol.

The aliphatic ester-forming carboxylic acids are those containing from 12 to 24 carbon atoms. Such acids may be characterized by the following general formula R ₁- (CO) OH, wherein R₁Is a hydrocarbon group which may be a straight chain hydrocarbon group, a branched chain or a cyclic hydrocarbon group or a mixture thereof. Preference is given to linear hydrocarbon radicals having from 12 to 24 carbon atoms, for example from 14 to 20 or from 16 to 18 carbon atomsAnd (4) a base. Such acids may also be used in combination with acids having more or fewer carbon atoms.

In general, the acid R₁- (CO) OH is a monocarboxylic acid because polycarboxylic acids tend to form polymeric products if the reaction conditions and amounts of reactants are not carefully adjusted. However, mixtures of monocarboxylic acids and small amounts of dicarboxylic acids or anhydrides can be used to prepare the esters. Examples of carboxylic acids include dodecanoic acid, stearic acid, lauric acid, behenic acid, and oleic acid.

The aforementioned esters are in particular monoesters of such polyols and such carboxylic acids. The preferred ester is glycerol monooleate. It will be understood that as with other such materials, glycerol monooleate is on its commercial scale to include mixtures of such materials as glycerol, oleic acid, other long chain acids, glycerol dioleate and glycerol trioleate. It is believed that the commercially available material comprises about 60 + -5% by weight of the chemical substance "glyceryl monooleate", as well as 35 + -5% of glyceryl dioleate and less than about 5% of trioleate and oleic acid. The amounts of monoester described below are calculated based on the actual corrected amount of polyol monoester present in any such mixture.

The amount of the foregoing esters in the lubricant composition is typically on the order of about 0.01 to about 1.0 wt.% of the lubricant composition, but can also be about 0.05 to about 0.5 or 0.8 or about 0.1 to about 0.6 wt.%.

In addition to the foregoing esters, the lubricant composition may also contain an ester of an alcohol with an aliphatic carboxylic acid containing from about 4 to about 8 carbon atoms.

Alcohols include both monohydric and polyhydric alcohols (i.e., polyols). The carbon atoms of the alcohol may be linear, branched, or mixtures thereof.

Suitable polyols are the same as described above.

When branched, the alcohol may be a guerbet alcohol or a mixture thereof. The guerbet alcohol can have an alkyl group including: 1) containing C_15-16Alkyl radicals of polymethylene radicals, e.g. 2-C_1-15Alkyl-hexadecyl (e.g., 2-octylhexadecyl) and 2-alkyl-octadecyl (e.g., 2-ethyloctadecyl, 2-tetradecyl-octadecyl, and 2-hexadecyloctadecyl); 2) containing C_13-14PolymethyleneAlkyl radicals of radicals, e.g. 1-C_1-15Alkyl-tetradecyl (e.g., 2-hexyltetradecyl, 2-decyltetradecyl, and 2-undecyltridecyl) and 2-C_1-15Alkyl-hexadecyl (e.g., 2-ethyl-hexadecyl and 2-dodecylhexadecyl); 3) containing C_10-12Alkyl radicals of polymethylene radicals, e.g. 2-C _1-15Alkyl-dodecyl (e.g. 2-octyldodecyl) and 2-C_1-15Alkyl-dodecyl (2-hexyldodecyl and 2-octyldodecyl), 2-C_1-15Alkyl-tetradecyl (e.g., 2-hexyltetradecyl and 2-decyltetradecyl); 4) containing C_6-9Alkyl radicals of polymethylene radicals, e.g. 2-C_1-15Alkyl-decyl radicals (e.g. 2-octyldecyl) and 2, 4-di-C_1-15Alkyl-decyl (e.g., 2-ethyl-4-butyl-decyl); 5) containing C_1-5Alkyl groups of polymethylene groups such as 2- (3-methylhexyl) -7-methyl-decyl and 2- (1,4, 4-trimethylbutyl) -5,7, 7-trimethyl-octyl; and 6) and mixtures of two or more branched alkyl groups, e.g. corresponding to propylene oligomers (hexamer to undecamer), ethylene/propylene (molar ratio 16:1 to 1:11) oligomers, isobutylene oligomers (pentamer to octamer), C_5-17The alkyl residues of oxo alcohols of alpha-olefin oligomers (dimers to hexamers).

Examples of suitable branched monoalcohols include 2-ethylhexanol, 2-butyloctanol, 2-hexyldecanol, 2-octyldodecanol, 2-decyltetradecanol, isotridecanol, isooctanol, oleyl alcohol, guerbet alcohol, or mixtures thereof. Examples of monohydric, linear alcohols include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, or mixtures thereof. In one embodiment, the monohydric alcohol contains 6 to 30, or 8 to 20, or 8 to 15 carbon atoms (typically 8 to 15 carbon atoms).

The aliphatic carboxylic acid forming the ester are those containing from 4 to 8 carbon atoms. Although aliphatic, the aliphatic carboxylic acid may be along C₄To C₈The alkyl backbone contains ethylenically unsaturated groups. In addition, such acids may be monocarboxylic or dicarboxylic acids or acidsAnhydrides or mixtures thereof. Examples of carboxylic acids include, for example, succinic acid, maleic acid, fumaric acid, glutaconic acid, glutaric acid, adipic acid, citraconic acid, mesaconic acid, pimelic acid, suberic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, and the like.

Particularly preferred esters may be adipates, e.g. C_8-13Or C_8-12Adipates, such as diisooctyl adipate or ditridecyl adipate. Other esters may include, for example, pentaerythritol esters, neopentyl esters, and trimethylol esters.

The amount of the foregoing esters in the lubricant composition is typically on the order of about 0.1 to about 3.0 wt.%, but may also be about 0.2 to about 2.5 or 0.3 to about 2.0 wt.% of the lubricant composition.

Carboxylic acid esters are prepared by the well known reaction of at least one carboxylic acid (or reactive equivalent thereof, such as an ester, halide, or anhydride) with at least one of the above-mentioned hydroxyl compounds.

Another component of the lubricant composition can be a metal deactivator. Examples of such materials include 2, 5-dimercapto-1, 3, 4-thiadiazole and/or derivatives thereof. Such materials are described in european patent publication 0761805, which is incorporated herein by reference.

Metal deactivators useful herein reduce corrosion of metals such as copper. Metal deactivators are also known as metal deactivators. These metal deactivators are typically nitrogen and/or sulfur containing heterocyclic compounds such as dimercaptothiadiazoles, triazoles, aminomercaptothiadiazoles, imidazoles, thiazoles, tetrazoles, hydroxyquinolines, oxazolines, imidazolines, thiophenes, indoles, indazoles, quinolines, benzoxazines, dithiols, oxazoles, oxatriazoles, pyridines, piperazines, triazines, and derivatives of any one or more thereof. The metal deactivator preferably comprises at least one triazole, which may be substituted or unsubstituted. Examples of suitable compounds are benzotriazole, alkyl-substituted benzotriazoles (e.g. tolyltriazole, ethylbenzotriazole, hexylbenzotriazole, octylbenzotriazole, etc.), aryl-substituted benzotriazoles (e.g. phenol benzotriazole, etc.) and alkylaryl or arylalkyl-substituted benzotriazoles as well as substituted benzotriazoles, wherein the substituents can be hydroxy, alkoxy, halo (especially chloro), nitro, carboxy and carboxyalkoxy. Preferably, the triazole is a benzotriazole or an alkylbenzotriazole wherein the alkyl group contains from 1 to about 20 carbon atoms, preferably from 1 to about 8 carbon atoms. Benzotriazole and tolyltriazole are useful.

In one embodiment, the metal deactivator is the reaction product of a dispersant and dimercaptothiadiazole. Dispersants can generally be characterized as reaction products of carboxylic acids with amines and/or alcohols. These reaction products are commonly used as dispersants in the lubricant art, sometimes collectively referred to as dispersants, despite the fact that they may have other uses in addition to or in lieu of dispersants. The carboxylic acid dispersant includes a succinimide dispersant, an ester-type dispersant, and the like. Succinimide dispersants are typically the reaction of a polyamine with an alkenyl succinic anhydride or acid. The ester-type dispersant is a reaction product of an alkenyl succinic anhydride or acid and a polyol compound. The reaction product may then be additionally treated with an amine such as a polyamine. Examples of useful dispersants are disclosed in U.S. Pat. nos. 3,219,666 and 4,234,435, which are incorporated herein by reference. Useful dispersants also include the ashless dispersants discussed below. Typically, the reaction occurs between the dispersant and the dimercaptothiadiazole by mixing the dispersant and dimercaptothiadiazole and heating to a temperature above about 100 ℃. U.S. Pat. nos. 4,140,643 and 4,136,043 describe compounds prepared by the reaction of such dispersants with dimercaptothiadiazoles. These patents are incorporated herein by reference for their disclosure of dispersants, dimercaptothiadiazoles, methods of reacting the two, and products obtained from such reactions.

In one embodiment, the metal deactivator is the reaction product of a phenol with an aldehyde and dimercaptothiadiazole. The phenol is preferably an alkylphenol in which the alkyl group contains at least about 6, preferably 6 to about 24, more preferably about 6 or about 7 to about 12 carbon atoms. The aldehyde is preferably an aldehyde or aldehyde synthon containing from 1 to about 7 carbon atoms, such as formaldehyde. Preferably, the aldehyde is formaldehyde or paraformaldehyde. The aldehyde, phenol, and dimercaptothiadiazole are typically reacted by mixing them at a temperature of up to about 150 ℃, preferably about 50 ℃ to about 130 ℃, in a molar ratio of about 0.5 to about 2 moles of phenol and about 0.5 to about 2 moles of aldehyde per mole of dimercaptothiadiazole. Preferably, the three reagents are reacted in equal molar amounts.

In one embodiment, the metal deactivator is a bis (hydrocarbyl dithio) thiadiazole. Preferably, each hydrocarbyl group is independently an alkyl, aryl, or aralkyl group having from 6 to about 24 carbon atoms. Each hydrocarbyl group may independently be t-octyl, nonyl, decyl, dodecyl, or ethylhexyl. The metal deactivator may be bis-2, 5-tert-octyl-dithio-1, 3, 4-thiadiazole or a mixture thereof with 2-tert-octylthio-5-mercapto-1, 3, 4-thiadiazole. These materials are commercially available under the trade name Amoco 150, which is available from Amoco Chemical Company (Amoco Chemical Company). These dithiothiadiazole compounds are disclosed as component (d) in PCT publication WO 88/03551, which is incorporated by reference for its disclosure of dithiothiadiazole compounds. In a preferred embodiment, the metal deactivator is a dimercaptothiadiazole derivative. D-1 and D-2 are specific examples below.

Example D-1

2, 5-dimercapto-1, 3, 4-thiadiazole and tert-nonylthiol are subjected to oxidative coupling; 100% chemical, 36% S, 64% N.

Example D-2

Coupling heptylphenol with 2, 5-dimercapto-1, 3, 4-thiadiazole using formaldehyde (thiadiazole generated in situ); 20% oil, 17.75% S, 5.5% N.

When used, the amount of metal deactivator in the lubricant composition is generally in the range of about 0.01 to about 0.5 weight percent based on the weight of the lubricant composition. In some embodiments, the amount of metal deactivator ranges from about 0.02 to about 0.42 wt.%, or from about 0.03 to about 0.33 wt.%, or from about 0.04 to about 0.24 wt.%, based on the weight of the lubricant composition.

The lubricant composition may also contain a poly (meth) acrylate polymer viscosity modifier. As used herein, the following ranges for the viscosity modifier are measured by GPC using polystyrene standards having a weight average molecular weight in the range of 350 to 2,000,000.

In one embodiment, the lubricant composition includes a linear poly (meth) acrylate polymer having a weight average molecular weight of 5,000 to 25,000, or 8000 to 20,000.

The linear poly (meth) acrylate polymer may be present in the lubricant composition at about 0.1 wt% to about 5 wt%, or 0.1 wt% to 4 wt%, or 0.2 wt% to 3 wt%, or 0.5 wt% to 3 wt%, 0.5 wt% to 4 wt% of the lubricant composition.

The poly (meth) acrylate polymer may be derived from a monomer composition comprising: (a)50 to 95 wt%, or 60 to 80 wt% of an alkyl (meth) acrylate, wherein the alkyl group of the (meth) acrylate has 10 to 15 carbon atoms; (b)1 to 40 wt%, or 4 to 35 wt% of an alkyl (meth) acrylate, wherein the alkyl group of the (meth) acrylate has 1 to 9 carbon atoms; (c)1 to 10 wt%, or 1 to 8 wt% of a monomer having dispersant functionality, (d)0 to 4 wt%, or 0 to 2 wt%, or 0 wt% of a vinyl aromatic monomer (typically styrene); and (e)0 wt% to 9 wt%, or 0 wt% to 6 wt% of an alkyl (meth) acrylate, wherein the alkyl group of the (meth) acrylate has 16 to 18 carbon atoms. In one embodiment, the linear polymer may contain from 0 wt% to 20 wt% of 16 to 18 alkyl (meth) acrylate.

In one embodiment, the linear polymer comprises a poly (meth) acrylate (typically a polymethacrylate) whose units are derived from a mixture of alkyl (meth) acrylate monomers that (a) contain from 8 to 24, or from 10 to 18, or from 12 to 15 carbon atoms in the alcohol-derived portion of the ester group and (b) contain from 6 to 11, or from 8 to 8 carbon atoms in the alcohol-derived portion of the ester group, and which have 2- (C) _1-4Alkyl) -substituents, and optionally at least one monomer selected from the group consisting of: (meth) acrylic esters, vinyl aromatic compounds (or vinyl aromatic monomers) containing 1 to 7 carbon atoms in the alcohol-derived portion of the ester group and different from the (meth) acrylic esters (a) and (b); and a nitrogen-containing vinyl monomer; with the proviso that no more than 60 wt.%, or no more than 50 wt.%, or no more than 35 wt.% of the esters contain no more than 10 carbon atoms in the alcohol-derived portion of the ester group. Linear polymers of this type are described in more detail in U.S. Pat. No. 6,124,249 or EP0937769A 1 paragraph [0019]And [0031]To [0067]In (1). (when written as R' C (═ O) -OR, "alcohol-derived moiety" refers to the "-OR" moiety of the ester, whether OR not it was actually prepared by reaction with an alcohol). Optionally, the linear polymer may additionally contain a third monomer. The third monomer may be styrene or a mixture thereof. The third monomer may be present in an amount of 0% to 25% of the polymer composition, or 1% to 15% of the composition, 2% to 10% of the composition, or even 1% to 3% of the composition.

Typically, the molar ratio of ester (a) to ester (b) in the copolymer is in the range of 95:5 to 35:65, or 90:10 to 60:40, or 80:20 to 50: 50.

The esters are typically aliphatic esters, typically alkyl esters. In one embodiment, the ester of (a) may be (meth) acrylic acid C_12-15The alkyl ester, and the ester of (b) may be 2-ethylhexyl (meth) acrylate.

In one embodiment, the ester group in ester (a) contains a branched alkyl group. The ester groups may contain from 2 to 65%, or from 5 to 60% of ester groups having branched alkyl groups. The branched alkyl groups may be beta-branched and may contain 8 to 60, or 8 to 30, or 8 to 16 carbon atoms. For example, the branched alkyl group can be derived from 2-ethylhexanol, 2-butyloctanol, 2-hexyldecanol, 2-octyldodecanol, 2-decyltetradecanol, or mixtures thereof, or commercially available alcohols, such as those available from Sasol (Sasol)

Branched Guerbet alcohols.

C_1-4The alkyl substituents can be methyl, ethyl, and any isomers of propyl and butyl.

The linear poly (meth) acrylate may have a weight average molecular weight of 45,000 or less, or 35,000 or less, or 25,000 or less, or 8000 to 25,000, or 10,000 to 35,000, or 12,000 to 20,000.

The linear polymer may be referred to as a viscosity modifier, or dispersant viscosity modifier, because it may exhibit dispersant functionality. Reference herein to a "dispersant viscosity modifier" does not include a dispersant, which is a class of individual compounds. Linear polymers are useful as A separate viscosity modifier (or dispersant viscosity modifier) present at 0.5 wt% to 4 wt% of a linear (meth) acrylic polymer viscosity modifier having dispersant functionality, wherein the linear polymer has a weight average molecular weight of 5,000 to 25,000, or 10,000 to 20,000, and wherein the oil of lubricating viscosity has a kinematic viscosity at 100 ℃ of 2.8 to 3.1 cSt (millimeters)²Per second) and a viscosity index of 104 to 130.

In one embodiment, the lubricant composition may contain only two linear polymer viscosity modifiers with dispersant functionality, wherein the linear polymer has a weight average molecular weight of 5,000 to 25,000, or 10,000 to 20,000,

in one embodiment, the lubricating composition can comprise 0.1 wt% to 4 wt% (or 0.2 wt% to 3 wt%) of a linear (meth) acrylic polymer viscosity modifier with dispersant functionality, wherein the linear polymer has a weight average molecular weight of greater than 25,000 to 400,000 (or to 350,000), or 30,000 to 150,000. A linear (meth) acrylic polymer having a weight average molecular weight of greater than 25,000 to 400,000 (or to 350,000) can be considered chemically similar to a linear (meth) acrylic polymer having a weight average molecular weight of 5,000 to 25,000, except that the weight average molecular weight is different.

The lubricating composition may comprise a linear polymer viscosity modifier with dispersant functionality comprising: 0.1 to 4 wt% (or 0.2 to 3 wt%) of a linear (meth) acrylic polymer viscosity modifier with dispersant functionality, wherein the linear polymer has a weight average molecular weight of 10,000 to 20,000; and 0.1 to 4 wt% (or 0.2 to 3 wt%) of a linear (meth) acrylic polymer viscosity modifier with dispersant functionality, wherein the linear polymer has a weight average molecular weight of greater than 20,000 to 250,000 (or 30,000 to 150,000).

The molecular weight of the viscosity modifier has been determined using known methods (e.g., GPC analysis using polystyrene standards), as described below. Methods for determining the molecular weight of polymers are well known. Methods are described, for example, in: (i) flory, "(Principles of Star Polymer Chemistry)," Kannell University Press (Cornell University Press)91953), Chapter VII, page 266-; or (ii) "Polymer: introduction to Star Polymer Science (Macromolecules, an Introduction to Polymer Science), eds., F.A. Bovey and F.H. Winslow, Academic Press (Academic Press) (1979), p.296-312.

Another component of the present invention is a borated epoxide containing 12 to 24 carbon atoms. This material may alternatively be described as a borate ester of a vicinal diol containing 12 to 24 carbon atoms. Such materials can be represented by the following structures

Wherein R is¹、R²、R³And R⁴Each independently hydrogen or an aliphatic radical, or any two thereof together with the carbon atom or atoms to which they are attached form a cyclic radical. Preferably, at least one of the R groups is an alkyl group containing at least 8 or at least 10 carbon atoms. In one embodiment, one of the R groups is such an alkyl group and the remaining R groups are hydrogen. Borated epoxides are described in detail in U.S. patent No. 4,584,115. Borated epoxides are typically prepared by reacting an epoxide with a boron source, such as boric acid or boron trioxide. Borated epoxides are not epoxides per se, but are ring-opening boron-containing reaction products of epoxides. Suitable epoxides include C_14-16Or C_14-18Or C_16-18Commercially available mixtures of epoxides, which are available from Elf-Atochem or Union Carbide, may be prepared from the corresponding olefins by known methods. Purified epoxy compounds, such as 1, 2-epoxyhexadecane, are available from Aldrich Chemicals (Aldrich Chemicals). The borated compounds are prepared by blending the boron compound and the epoxide and heating them at a suitable temperature (typically 80 to 250 ℃) until the desired reaction occurs. An inert liquid such as toluene, xylene or dimethylformamide may be used as the reaction medium. Water is formed during the reaction and is usually distilled off. Alkaline reagents may be used to catalyze the reaction. Superior food The borated epoxide selected is a borated epoxide of predominantly 16 carbon olefins. The borate ester epoxide may be present in an amount of 0.01 or 0.05 to 0.5 or 1.0 parts by weight of the composition, or alternatively, 0.1 to 0.9%.

Other optional materials may include mixtures of at least two antioxidants, such as aromatic amine antioxidants, hindered phenolic antioxidants including ester-containing hindered phenolic antioxidants, and sulfurized olefin antioxidants. These antioxidants may optionally be present in an amount of 0.01 to 5, or 0.15 to 4.5, or 0.2 to 4, or 0.2 to 2 weight percent.

In one embodiment, the lubricating composition of the present invention includes an arylamine antioxidant. The arylamine antioxidant may be phenyl-alpha-naphthylamine (PANA) or a hydrocarbyl-substituted diphenylamine, or mixtures thereof. The hydrocarbyl-substituted diphenylamine may comprise mono-or di-C₄To C₁₆-, or C₆To C₁₂-, or C₉-an alkyl diphenylamine. For example, the hydrocarbyl-substituted diphenylamine may be octyldiphenylamine, or dioctyldiphenylamine, dinonyldiphenylamine, typically dinonyldiphenylamine.

When present, the arylamine antioxidant may be present from 0.2 wt% to 1.2 wt%, or from 0.3 wt% to 1.0 wt%, or from 0.4 wt% to 0.9 wt%, or from 0.5 wt% to 0.8 wt% of the lubricating composition.

Hindered phenolic antioxidants typically contain a secondary butyl and/or a tertiary butyl group as a sterically hindering group. The phenolic group is typically additionally substituted with a hydrocarbyl group and/or a bridging group attached to a second aromatic group. Examples of suitable hindered phenol antioxidants include 2, 6-di-tert-butylphenol, 4-methyl-2, 6-di-tert-butylphenol, 4-ethyl-2, 6-di-tert-butylphenol, 4-propyl-2, 6-di-tert-butylphenol or 4-butyl-2, 6-di-tert-butylphenol or 4-dodecyl-2, 6-di-tert-butylphenol. In one embodiment, the hindered phenol antioxidant may be an ester and may include, for example, Irganox from Ciba (Ciba)^TML-135 or butyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate.

If present, the hindered phenolic antioxidant may be present at 0.1 wt% to 1 wt%, or 0.2 wt% to 0.9 wt%, or 0.1 wt% to 0.4 wt%, or 0.4 wt% to 1.0 wt% of the lubricating composition.

Antioxidants also include sulfurized olefins, such as monosulfides or disulfides, or mixtures thereof. These materials typically have a sulfur bond with 1 to 10 sulfur atoms, for example 1 to 4 or 1 or 2 sulfur atoms. Materials that may be sulfurized for use as a sulfurized antioxidant in a lubricant composition may include oils, fatty acids and esters, olefins and polyolefins prepared therefrom, terpenes, or Diels-Alder (Diels-Alder) adducts. Details of methods for preparing some such vulcanized materials can be found in U.S. Pat. nos. 3,471,404 and 4,191,659.

The lubricating composition may also include a calcium-containing detergent. Although it is preferred that no calcium-containing detergent is present, the calcium-containing detergent may be included in an amount that delivers up to 300ppm of calcium, or 30ppm to 300ppm, or 30ppm to 275ppm, or 60ppm to 250ppm, or even 60ppm to 225ppm of calcium to the composition.

In some embodiments, the calcium-containing detergent may be present at 900ppm or less, or 1 to 900ppm, or even 5 to 800ppm, or 10 to 700ppm, or even 15 to 600, or 500 ppm.

The calcium-containing detergent may be an overbased detergent, a non-overbased detergent, or a mixture thereof. Typically, detergents are overbased.

The preparation of calcium-containing detergents is known in the art. Patents describing the preparation of overbased calcium-containing detergents include U.S. Pat. nos. 2,501,731; 2,616,905, respectively; 2,616,911, respectively; 2,616,925, respectively; 2,777,874, respectively; 3,256,186, respectively; 3,384,585, respectively; 3,365,396, respectively; 3,320,162, respectively; 3,318,809, respectively; 3,488,284; and 3,629,109.

The calcium-containing detergent may be a non-overbased detergent (also referred to as a neutral detergent). The non-overbased TBN may be from 20 to less than 200, or from 30 to 100, or from 35 to 50mg KOH/g. The TBN of the non-overbased calcium containing detergents may also be from 20 to 175, or from 30 to 100mg KOH/g. When the non-overbased calcium-containing detergents are prepared from strong acids such as hydrocarbyl-substituted sulfonic acids, the TBN may be lower (e.g., 0 to 50mg KOH/g, or 10 to 20mg KOH/g).

As used herein, the TBN values of the TBN cited and related ranges are on an "as is" basis, i.e., containing conventional amounts of diluent oil. Conventional amounts of diluent oil typically range from 30 wt% to 60 wt% (typically 40 wt% to 55 wt%) of the detergent component.

The calcium containing detergent may be an overbased detergent with a TBN of, for example, greater than 200mg KOH/g (typically 250 to 600, or 300 to 500mg KOH/g).

Overbased calcium-containing detergents may be formed by the reaction of an alkaline calcium compound and an acidic detergent matrix. The acidic detergent matrix may comprise an alkyl aromatic sulfonic acid (e.g., alkyl naphthalene sulfonic acid, alkyl toluene sulfonic acid, or alkyl benzene sulfonic acid), alkyl salicylic acid, or mixtures thereof.

The alkaline calcium compound is used to provide alkalinity to the detergent. The basic calcium compound is a compound of hydroxide or oxide of calcium.

The oxides and/or hydroxides may be used alone or in combination. The oxide or hydroxide may be hydrated or dehydrated, although hydration is typical. In one embodiment, the basic calcium compound may be calcium hydroxide, which may be used alone or in admixture with other metal basic compounds. Calcium hydroxide is commonly referred to as lime. In one embodiment, the calcium basic compound may be calcium oxide, which may be used alone or in admixture with other metal basic compounds.

In one embodiment, the calcium-containing detergent may be a sulfonate or a mixture thereof. The sulfonate salts can be prepared from benzene (or naphthalene, indenyl, indanyl, or biscyclopentadienyl) sulfonic acids substituted with a mono-or dihydrocarbyl group, wherein the hydrocarbyl group can contain 6 to 40, or 8 to 35, or 9 to 30 carbon atoms.

The hydrocarbyl group may be derived from polypropylene or a linear or branched alkyl group containing at least 10 carbon atoms. Examples of suitable alkyl groups include branched and/or straight chain decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, octadecenyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl groups or mixtures thereof.

In one embodiment, the hydrocarbyl-substituted sulfonic acid may include polypropene benzenesulfonic acid and/or C₁₆-C₂₄Alkyl benzene sulfonic acidOr a mixture thereof.

In one embodiment, the calcium sulfonate detergent may be primarily a linear alkylbenzene sulfonate detergent with a metal ratio of at least 8, as described in U.S. patent application 2005065045 (and to US 7,407,919) paragraphs [0026] through [0037 ]. In some embodiments, the linear alkyl group may be attached to the benzene ring anywhere along the linear chain of the alkyl group, but often in the 2, 3, or 4 position of the linear chain, and in some cases primarily in the 2 position.

When neutral or weakly basic, the TBN of the calcium sulfonate detergent may be less than 100, or less than 75, and typically from 20 to 50mg KOH/g, or from 0 to 20mg KOH/g.

When overbased, the TBN of the calcium sulfonate detergent may be greater than 200, or 300 to 550, or 350 to 450mg KOH/g.

Phenate detergents are typically derived from a para-hydrocarbyl phenol or typically an alkylphenol. Alkylphenols of this type can be coupled to sulfur and overbased, coupled to aldehydes and overbased, or carboxylated to form salicylate detergents. Suitable alkyl salicylates include those alkylated with oligomers of propylene, oligomers of butylene, especially tetramers and pentamers of n-butene, and those alkylated with alpha-olefins, isomerized alpha-olefins, and polyolefins such as polyisobutylene. In one embodiment, the lubricating composition comprises less than 0.2 wt%, or less than 0.1 wt%, or even less than 0.05 wt% salicylate detergent derived from PDDP. In one embodiment, the lubricant composition comprises a salicylate detergent not derived from PDDP. In one embodiment, the lubricating composition comprises a salicylate detergent prepared from PDDP, such detergent containing less than 1.0 wt% unreacted PDDP, or less than 0.5 wt% unreacted PDDP, or being substantially free of PDDP.

The detergent may be borated or non-borated.

The chemical structures of sulfonate and salicylate detergents are known to those skilled in the art. A standard textbook entitled "lubricant Chemistry and Technology of lubricating", third edition, edited by r.m. mortier and s.t. orszulik, copyright 2010, pages 220 to 223, provides a general disclosure of the detergent and its structure under sub-title 7.2.6.

In one embodiment, the calcium-containing detergent may be an overbased calcium sulfonate, an overbased calcium salicylate, or a mixture thereof. Typically, the detergent may be an overbased calcium sulfonate.

In one embodiment, a calcium-containing detergent may be mixed with a detergent containing zinc, barium, sodium, or magnesium. Detergents containing zinc, barium, sodium or magnesium are also well known in the art and are described in the same references describing calcium containing detergents. However, the TBN and metal ratios may be slightly different. The detergent containing zinc, barium, sodium or magnesium may be a phenate, sulphur containing phenate, sulphonate, salicylate alkoxide or salicylate. Typically, the detergent containing zinc, barium, sodium or magnesium may be magnesium phenate, magnesium sulphur containing phenate or magnesium sulphonate.

More detailed descriptions of the expressions "metal ratio", TBN and "soap content" are known to the person skilled in the art and are explained in standard textbooks, such as "lubricant chemistry and technology", third edition, edited by r.m. mortier and s.t. orszulik, copyright 2010, pages 219 to 220, in the detergent classification under the sub-title 7.2.5.

Another material often used in transmissions is a dispersant. Dispersants may include, for example, "succinimide dispersants," which are materials of carboxylic acid dispersants prepared by reaction of hydrocarbyl-substituted succinic anhydride or reactive equivalents thereof with amines such as poly (ethyleneamines); "amine dispersants" which are the reaction products of relatively high molecular weight aliphatic or cycloaliphatic halides and amines (e.g., polyalkylene polyamines); "Mannich dispersants", i.e., reaction products of alkyl phenols in which the alkyl group contains at least 30 carbon atoms with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines); and "ester dispersants," similar to the succinimide dispersants described above, except that they can be considered as being made by reacting a hydrocarbyl acylating agent with a polyhydric aliphatic alcohol (such as glycerol, pentaerythritol, or sorbitol), as described in U.S. Pat. No. 3,381,022. Post-treated dispersants may also be used. Post-treated dispersants are typically obtained by reacting a carboxylic acid (e.g., succinimide), amine or mannich dispersant with an agent such as urea, thiourea, carbon disulfide, an aldehyde, a ketone, a carboxylic acid, a hydrocarbon-substituted succinic anhydride, a nitrile, an epoxide, a boron compound such as boric acid (to produce a "borated dispersant" as described above), a phosphorus compound such as phosphoric acid or an anhydride, 2, 5-dimercaptothiadiazole (DMTD), or an aromatic diacid having an acid group in the 1,3 or 1,4 position on the benzene ring (e.g., terephthalic acid). Mixtures of dispersants may also be used. The nitrogen content of the dispersant can be greater than or equal to about 11,000ppm, or greater than or equal to about 11,500ppm, or greater than or equal to about 12,000ppm, based on the weight of the dispersant.

The total amount of dispersant(s), whether post-treated (e.g., borated or non-borated, but preferably borated) or a combination thereof, in the composition can be, for example, from 0.01 to 1.8 weight percent, or, for example, from 0.025 to 1.5 weight percent or from 0.05 to 1.25 weight percent of the final blended fluid formulation, although in concentrates the amounts will be proportionately higher. To the extent that the dispersant is borated, the dispersant can provide less than 100ppm boron, or less than 90ppm boron, or even less than 80ppm boron to the composition, and in some cases, less than 70ppm boron to the composition.

The lubricant composition preferably exhibits a viscosity of at most 7.0 x 10 at 100 ℃ and 500V as measured by ASTM D2624^-10Conductivity of S/cm, or 6.5X 10^-10S/cm, or 6.0X 10^-10S/cm, or 5.5X 10^-10S/cm, or 5.0X 10^-10Conductivity of S/cm. It is highly preferred that the lubricant composition not have electrical conductivity, but in practice may achieve an order of magnitude of 4.0 x 10 at 100 deg.c^-10Or 4.5X 10^-10The electrical conductivity of (1).

In one embodiment, the lubricant composition is substantially free of friction modifiers. In some embodiments, the lubricant composition is completely free of friction modifiers.

The lubricant composition will be suitable for lubricating a transmission. In particular, the lubricant composition will be suitable for lubricating a transmission in a vehicle having an electric motor, which may be an all-electric vehicle or a hybrid electric vehicle having both an electric motor and an engine powered by a hydrocarbon or other fuel. The kinematic viscosity at 40 ℃ of the lubricant composition for a transmission is preferably from 8cSt to 18cSt, or for example from 8cSt to 16cSt, or even from 8cSt to 15cSt, or from 9cSt to 15 or 16cSt, or for example from 8cSt to 12.5 or 13cSt, or even from 9cSt to 12.5 or 13cSt, or from 10cSt to 12 cSt. Accordingly, one aspect is a method of lubricating a transmission, and in particular a transmission in a vehicle having an electric motor, the method comprising supplying into the transmission a lubricant composition as disclosed herein, and operating the transmission.

Transmissions to which the lubricant composition is applicable include automatic transmissions and dual clutch transmissions. The transmission may or may not include a shifting clutch, and where the transmission includes a shifting clutch, the clutch may be a dry clutch or a wet clutch. In one embodiment, the lubricant may be used on a transmission that does not include a shifting clutch. In another embodiment, the lubricant composition may be used in a transmission having a wet clutch. In further embodiments, the lubricant composition may be used in a transmission having a dry clutch.

As used herein, the term "condensation product" is intended to encompass esters, amides, imides, and other such materials, which can be prepared by the condensation reaction of an acid or reactive equivalent of an acid (e.g., an acid halide, anhydride, or ester) with an alcohol or amine, whether or not the condensation reaction is actually performed to directly produce 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 is still considered to be a condensation product.

Unless otherwise indicated, each chemical component is present in an amount based on the active chemical species, excluding any solvent or diluent oil that may be typically present in a commercial material. However, unless otherwise indicated, each chemical species or composition referred to herein should be interpreted as a commercial grade material, which may contain isomers, by-products, derivatives, and other such materials as are commonly understood to be present in the commercial grade.

As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense as is well known to those skilled in the art. In particular, it refers to a group having carbon atoms directly attached to the rest of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:

hydrocarbon substituents, that is, aliphatic substituents (e.g., alkyl or alkenyl), alicyclic substituents (e.g., cycloalkyl, cycloalkenyl), and aromatic substituents substituted with aromatic, aliphatic, and alicyclic groups, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form a ring);

substituted hydrocarbon substituents, that is, substituents other than hydrocarbyl containing substituents which do not alter the predominantly hydrocarbon nature (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy), in the context of this invention;

hetero substituents, that is, substituents that, while having a predominantly hydrocarbon character in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms and encompass substituents such as pyridyl, furyl, thienyl and imidazolyl. Heteroatoms include sulfur, oxygen, and nitrogen. Typically, no more than two or no more than one non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; alternatively, non-hydrocarbon substituents may not be present in the hydrocarbyl group.

It is known that some of the above materials may interact in the final formulation and therefore the components of the final formulation may be different from those initially added. For example, metal ions (e.g., of detergents) can migrate to other acidic or anionic sites of other molecules. The products formed thereby, including products formed when employing the compositions of the present invention in their intended use, may not be readily described. Nevertheless, all such modifications and reaction products are intended to be included within the scope of the present invention; the present invention encompasses compositions prepared by blending the above components.

As used herein, the term "about" means that the value of a given quantity is within ± 20% of the stated value. In other embodiments, the value is within ± 15% of the specified value. In other embodiments, the value is within ± 10% of the specified value. In other embodiments, the value is within ± 5% of the specified value. In other embodiments, the value is within ± 2.5% of the specified value. In other embodiments, the value is within ± 1% of the specified value.

Additionally, as used herein, the term "substantially" means that a given number of values is within ± 10% of a stated value. In other embodiments, the value is within ± 5% of the specified value. In other embodiments, the value is within ± 2.5% of the specified value. In other embodiments, the value is within ± 1% of the specified value.

The invention herein may be used to lubricate an automatic transmission for a hybrid electric vehicle, as will be better understood with reference to the following example.

Examples of the invention

A number of formulations were prepared and tested for pitting.

Sample formulations were blended according to the following table.

Additional formulations were blended according to the table below.

The conductivity of the samples was measured using a Tettex 2830/2831 oil dielectric analyzer (electrode spacing of 2mm) equipped with a test cell (Tettex 2903) for liquid insulation material. 40ml of each sample was transferred to a test cell. The dissipation factor and dielectric constant (permittivity) were recorded at 100 ℃ ± 2 ℃ and 600V AC applied. The frequency was kept constant at 50 Hz. Resistivity measurements were also made at this temperature at +500V DC with a 3 minute short circuit time and a 1 minute power on time. The conductivity was calculated from the recorded final resistivity values.

Samples were also tested for pitting according to the 80 hour FZG pitting test. This test uses a 1500 gram oil sample and an FZG pitting tester with a speed set at 1,500RPM (8.65 meters/second) and an arm length of 0.5% at a sump temperature of 120 ℃. The test initially lasted 8 hours from the loading phase 7 and then checked whether there were any wear problems. If there is no wear problem, the test is restarted at load phase 8 and run for another 8 hours using the same speed and temperature. After rechecking the gears for any wear problems after the second 8 hour run, the samples were run at 120 ℃ for an additional 64 hours at the same 1,500RPM speed in the load phase 9. After completion, the number and size (in millimeters) of dimples per tooth on the pinion were checked using the measurement specification. The area of the highest micropitting tooth (in millimeters) is reported, as well as the total area of all micropits for all teeth. Lower levels of pitting are preferred.

The results of the conductivity and pitting tests are presented in the table below.

	1	2	3	4	5	6	7	8	9
										Electrical conductivity of	4.46	2.37	3.52	5.54	4.4	4.5	4.78	5.87	3.65
FZG pitting corrosion
										At most 1 tooth (at most 5)	0.12	0.12	0.24	0.5	0.5	0.75	1	1.62	2
Average all teeth (maximum 18)	0.12	0.12	0.72	0.5	1.22	0.75	1	1.74	2

	C1	C2	C3	C4	C5	C6	C7
								Electrical conductivity of	13.4	9	7.28	8.7	8.31	5.49	8.45
FZG pitting corrosion
								At most 1 tooth (at most 5)	0.24	0.5	2	4.25	9	10	27
Average all teeth (maximum 18)	0.24	1	4	10.37	21.12	11.49	131.5

Each of the documents mentioned above is incorporated herein by reference, including any previous applications to which priority is claimed, whether or not specifically listed above. Reference to any document is not an admission that such document is entitled to antedate such document by virtue of prior art or constitutes common knowledge of one of ordinary skill in any jurisdiction. Except by way of example, or where otherwise explicitly indicated, all numbers in this description specifying amounts of material, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word "about". It is to be understood that the upper and lower amount, range, and ratio limits described herein may be independently combined. Similarly, the ranges and amounts for each element of the invention can be used in combination with the ranges or amounts for any of the other elements.

As used herein, the transitional term "comprising" 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 statement herein that "comprises," it is intended that the term also encompasses, as alternative embodiments, the phrases "consisting essentially of … …" and "consisting of … …," wherein "consisting of … …" does not include any elements or steps not specified and "consisting essentially of … …" permits the inclusion of additional, unrecited elements or steps that do not materially affect the basic or basic and novel characteristics of the composition or method under consideration.

While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. In this regard, the scope of the invention is limited only by the following claims.

Claims (20)

1. A lubricant composition for lubricating a transmission in a vehicle having an electric motor comprising

a. Oil of lubricating viscosity

b.0.2 to 2.0% by weight of at least one borate ester of the formula I,

wherein each R is independently C₃To C₁₂An alkyl group, a carboxyl group,

c. at least one phosphorus-containing compound comprising a phosphite composition comprising the reaction product of monomeric phosphorous acid or an ester thereof and at least two alkylene glycols, said phosphorus-containing compound being present in an amount to deliver from 100 to 450ppm of phosphorus to said lubricating composition,

d. a dispersant in a total amount of 1.8 wt% or less and delivering less than 100ppm of boron to the lubricant composition, the dispersant comprising at least one of: a carboxylic acid dispersant prepared by reacting a hydrocarbyl-substituted carboxylic acid or reactive equivalent thereof with an amine; amine dispersants prepared by reacting high molecular weight aliphatic or alicyclic halides with amines; mannich dispersants prepared by reacting an alkylphenol having an alkyl group containing at least 30 carbon atoms with an aldehyde and an amine; and an ester dispersant prepared by reacting a hydrocarbyl acylating agent with a polyhydric aliphatic alcohol, and

e. Optionally a calcium-containing sulphonate or salicylate detergent or mixture thereof, present in an amount to deliver 300ppm or less of calcium to the lubricating composition,

wherein the lubricant composition has a kinematic viscosity at 40 ℃ of from 8cSt to 18cSt, and

wherein the ratio of phosphorus from the phosphite of (c) to the boron from the borate of (b) is greater than 0.7.

2. The lubricant composition of claim 1, wherein the phosphorus-containing compound further comprises phosphorous acid C_3-8A hydrocarbyl ester.

3. The lubricant composition of claim 1 additionally comprising 0.01 to 1.0 weight percent of an ester of (1) a polyol and 2) an aliphatic carboxylic acid containing 12 to 24 carbon atoms.

4. The lubricant composition of claim 2 additionally comprising 0.01 to 1.0 weight percent of an ester of (1) a polyol and 2) an aliphatic carboxylic acid containing 12 to 24 carbon atoms.

5. The lubricant composition of claim 3, wherein the ester is glycerol monooleate.

6. The lubricant composition of claim 4, wherein the ester is glycerol monooleate.

7. The lubricant composition of any one of claims 1-6 additionally comprising 0.1 to 3.0 wt% of an ester of (1) an alcohol and 2) an aliphatic carboxylic acid containing 4 to 8 carbon atoms.

8. The lubricant composition of claim 7, wherein the ester is C_8-13An ester of adipic acid.

9. The lubricant composition of any one of claims 1-6 and 8, further comprising 0.01 wt% to 0.5 wt% dimercaptothiadiazole or derivative thereof.

10. The lubricant composition of claim 7, further comprising 0.01 wt% to 0.5 wt% dimercaptothiadiazole or derivative thereof.

11. The lubricant composition of any one of claims 1-6, 8, and 10, further comprising 0.1 wt% to 5 wt% of a poly (meth) acrylate polymer viscosity modifier.

12. The lubricant composition of claim 11, wherein the poly (meth) acrylate polymer has a weight average molecular weight of 5,000 to 25,000.

13. The lubricant composition of any one of claims 1-6, 8, 10, and 12, further comprising 0.05 wt% to 1.0 wt% phosphorous acid C₁₂To C₂₄A hydrocarbyl ester.

14. The lubricant composition of any of claims 1-6, 8, 10, and 12, further comprising 0.01 wt% to 1.0 wt% of C_12-24Borating the epoxide.

15. The lubricant composition of claim 13, further comprising 0.01 to 1.0 wt% of C _12-24The epoxide is borated.

16. The lubricant composition of any one of claims 1-6, 8, 10, 12, and 15, further comprising 0.1 wt% to 3.0 wt% of a mixture of at least two antioxidants selected from the group consisting of hindered phenols, aryl amines, and sulfur-containing antioxidants.

17. The lubricant composition of claim 14, further comprising from 0.1 wt% to 3.0 wt% of a mixture of at least two antioxidants selected from the group consisting of hindered phenols, aryl amines, and sulfur-containing antioxidants.

18. The lubricant composition of any of claims 1-6, 8, 10, 12, 15, and 17, wherein the lubricant composition exhibits up to 7.0 x 10 as measured by ASTM D2624 at 100 ℃ and 500V^-10Conductivity of S/cm.

19. A method of lubricating a transmission comprising supplying to an automatic transmission the composition of any one of claims 1 to 18, and operating the transmission.

20. The method of claim 19, wherein the transmission does not include a shifting clutch.