JP5455170B2 - Lubricating composition comprising a compound derived from hydroxycarboxylic acid - Google Patents

Description

  The present invention relates to a lubricating composition comprising (a) a compound derived from a hydroxycarboxylic acid and (b) an oil of lubricating viscosity. The present invention further provides the use of a lubricating composition for lubricating a limited slip differential.

  Automotive limited slip differentials typically use wet multi-plate clutches, i.e., clutch plates immersed in a lubricant. The limited slip differential typically has a planetary bevel gear or a planetary spur gear and distributes the drive torque evenly across the two drive wheels regardless of their rotational speed. This allows the drive wheels to rotate without slipping between the drive wheels and the road surface during cornering, despite their different rotational speeds. In order to suppress the slip, a lubricant containing a compound capable of improving the friction performance, a dispersant, and a sulfur and / or phosphorus-containing extreme pressure agent can be used. Examples of this type of lubricant are disclosed in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, and Patent Document 5.

  Patent Document 7, Patent Document 8, and Patent Document 9 describe a lubricant containing a compound suitable for (i) adhesion suppression (Patent Document 6) and (ii) wear performance.

U.S. Pat. No. 4,308,154 US Pat. No. 5,547,586 US Pat. No. 4,180,466 U.S. Pat. No. 3,825,495 European Patent Application No. 0399764A1 US Pat. No. 3,284,409 International Publication No. 96/037585 US Patent Application Publication No. 2002/0119895 US Pat. No. 5,487,838

  We have found that the lubricating compositions and methods disclosed herein provide acceptable levels of (i) lubricant thermal stability, (ii) lubricant oxidation stability, (iii) high static friction coefficient, (iv) Fuel consumption, (v) adhesion suppression, (vi) seal compatibility, (vii) cleanliness, and (viii) chattering (ie, typically low frequency "growl" during faster cornering operations). It has been discovered that noise, vibration and harshness (NVH) tend to appear at least one of noise, vibration and harshness (NVH), which often appear as "sound" and "groan". The inventors have also unexpectedly discovered that the lubricant compositions and methods disclosed herein may also be suitable for slip limiting systems having one or more separate plates. For example, the plate may be a system that uses steel, paper, ceramic, carbon fiber, and a plate-like mixture of steel on ceramic, carbon fiber in paper, steel on paper, and the like.

  In one embodiment, the present invention provides a limited slip differential with a lubricating composition comprising (a) a derivative of hydroxycarboxylic acid (or a compound derived from hydroxycarboxylic acid) and (b) an oil of lubricating viscosity. A method of lubricating a limited slip differential is provided.

In one embodiment, the present invention provides an acceptable level of (i) lubricant thermal stability, (ii) lubricant oxidation stability, (iii) coefficient of friction, (iv) fuel consumption, (v) adhesion in a limited slip differential. (A) a derivative of hydroxycarboxylic acid (or a compound derived from hydroxycarboxylic acid) and (b) to provide at least one of inhibition, (vi) seal compatibility, and (vii) chattering (abnormal noise); Use of a lubricating composition comprising an oil of lubricating viscosity is provided. In one embodiment, the use provides an acceptable level of coefficient of friction.
For example, the present invention provides the following items.
(Item 1)
A method of lubricating a limited slip differential comprising supplying a lubricant composition comprising (a) a hydroxycarboxylic acid derivative and (b) an oil of lubricating viscosity to the limited slip differential.
(Item 2)
Item 2. The method according to Item 1, wherein the derivative of hydroxycarboxylic acid is a derivative of hydroxypolycarboxylic acid.
(Item 3)
The hydroxypolycarboxylic acid derivative is selected from the group consisting of hydroxycarboxylic acid diester, hydroxycarboxylic acid diamide, hydroxycarboxylic acid imide, hydroxycarboxylic acid diimide, hydroxycarboxylic acid ester amide, hydroxycarboxylic acid ester imide, and hydroxycarboxylic acid imide amide The method according to item 2, wherein:
(Item 4)
4. The method according to any of the preceding items 2 to 3, wherein the derivative of hydroxypolycarboxylic acid is selected from the group consisting of hydroxycarboxylic acid imide, hydroxycarboxylic acid diimide, hydroxycarboxylic acid ester imide and hydroxycarboxylic acid imide amide. .
(Item 5)
The method according to any one of the preceding items 2 to 4, wherein the derivative of hydroxypolycarboxylic acid is selected from the group consisting of hydroxycarboxylic acid imides and hydroxycarboxylic acid diimides.
(Item 6)
6. The method according to any one of the preceding items 2 to 5, wherein the derivative of hydroxypolycarboxylic acid is a derivative of tartaric acid, an imide derivative of citric acid, or a mixture thereof.
(Item 7)
The method according to any one of the preceding items 2 to 6, wherein the derivative of hydroxypolycarboxylic acid is an imide derivative of tartaric acid, an imide derivative of citric acid, or a mixture thereof.
(Item 8)
8. The method according to any one of items 2 to 7 above, wherein the derivative of hydroxypolycarboxylic acid is an imide derivative of tartaric acid or a mixture thereof.
(Item 9)
The hydroxycarboxylic acid derivative is present in an amount ranging from 0.1% to 5%, or from 0.2% to 3%, or from more than 0.2% to 3% by weight of the lubricating composition. 9. A method according to any of the preceding items 1 to 8, which is present.
(Item 10)
The method according to any of the preceding items 1 to 9, further comprising a sulfur-containing compound.
(Item 11)
Item 11. The method according to Item 10, wherein the sulfur-containing compound is dimercaptothiadiazole or a derivative or a mixture thereof.
(Item 12)
Item 11. The method according to Item 10, wherein the sulfur-containing compound is polysulfide or sulfurized olefin.
(Item 13)
13. A method according to any preceding item, wherein the lubricating composition further comprises a phosphorus-containing compound.
(Item 14)
Item 14. The method according to Item 13, wherein the phosphorus-containing compound is an amine salt of a phosphate ester.
(Item 15)
The amine salt of the phosphate ester is an amine that is either (i) a hydroxy-substituted diester of phosphoric acid or (ii) a hydroxy-substituted diester of phosphorylated phosphoric acid or a hydroxy-substituted triester of phosphorylated phosphoric acid Item 15. The method according to Item 14, which is a salt.
(Item 16)
16. A method according to any preceding item, wherein the lubricating composition further comprises a boron-containing compound.
(Item 17)
Item 17. The method according to Item 16, wherein the boron-containing compound is a borated dispersant, a borate ester, or a borated phospholipid.
(Item 18)
18. A method according to any of the preceding items 1 to 17, wherein the lubricating composition has a sulfur content in the range of 0.3 wt% to 5 wt%, or 0.8 wt% to 2.5 wt%. .
(Item 19)
19. A method according to any of the preceding items 1 to 18, wherein the lubricating composition is a top treatment concentrate.
(Item 20)
20. A method according to any preceding item, wherein the lubricating composition is a fully formulated fluid.
(Item 21)
Acceptable levels of (i) lubricant thermal stability, (ii) lubricant oxidation stability, (iii) coefficient of friction, (iv) fuel economy, (v) adhesion suppression, (vi) seal compatibility, (vii) cleanliness. And (viii) use of a derivative of a hydroxycarboxylic acid according to any of the preceding items 1 to 19 in a limited slip differential to provide at least one of chattering (abnormal noise).
(Item 22)
20. Use of a derivative of a hydroxycarboxylic acid according to any preceding item 1 to 19 in a limited slip differential to provide an acceptable level of friction.

  The present invention provides the lubricating compositions and methods disclosed above.

Compound Derived from Hydroxycarboxylic Acid The lubricating composition of the present invention comprises a derivative of hydroxycarboxylic acid (or a compound derived from hydroxycarboxylic acid) or a mixture thereof. As used herein, the expression “derivatives of” literally refers to materials that are literally “derived from” a designated hydroxycarboxylic acid, and whether it was actually prepared using the designated acid as a starting material, and potentially Is meant to include materials "derived from" hydroxycarboxylic acids. Derivatives of hydroxycarboxylic acids include materials that are or can be prepared by reaction of acid groups and / or alcohol groups, such as esters, amides, imides, mixtures of a plurality of such functional groups.

  Hydroxycarboxylic acids include monohydroxymonocarboxylic acids, polyhydroxymonocarboxylic acids, monohydroxypolycarboxylic acids and polyhydroxypolycarboxylic acids. Further, the hydroxypolycarboxylic acid can be a monohydroxypolycarboxylic acid such as citric acid or a polyhydroxypolycarboxylic acid such as tartaric acid. Examples of the derivative of hydroxycarboxylic acid (or a compound derived from hydroxycarboxylic acid) include amide, ester or imide derivatives of hydroxycarboxylic acid or a mixture thereof. Typically, the derivative of hydroxycarboxylic acid can be a derivative of hydroxypolycarboxylic acid such as tartaric acid.

  In one embodiment, the amide, ester or imide derivative of a hydroxycarboxylic acid is a hydroxycarboxylic acid diester, a hydroxycarboxylic acid diamide, a hydroxycarboxylic acid monoimide, a hydroxycarboxylic acid diimide, a hydroxycarboxylic acid ester amide, a hydroxycarboxylic acid ester imide and It can be at least one of hydroxycarboxylic imidoamides. In one embodiment, the amide, ester or imide derivative of hydroxycarboxylic acid may be at least one member of the group consisting of hydroxycarboxylic acid diester, hydroxycarboxylic acid diamide, and hydroxycarboxylic acid ester amide.

  Examples of suitable hydroxycarboxylic acids include citric acid, tartaric acid, lactic acid, glycolic acid, hydroxypropionic acid, hydroxyglutaric acid or mixtures thereof. In one embodiment, the amide, ester or imide derivative of hydroxycarboxylic acid can be derived from tartaric acid, citric acid, hydroxysuccinic acid, dihydroxymonoacid, monohydroxydiacid or mixtures thereof. In one embodiment, the amide, ester or imide derivative of hydroxycarboxylic acid comprises a tartaric acid or citric acid derivative or (or a compound derived from tartaric acid or citric acid). In one embodiment, the amide, ester or imide derivative of hydroxycarboxylic acid comprises a compound derived from tartaric acid.

  The derivative of hydroxycarboxylic acid is selected from the group consisting of hydroxycarboxylic acid diester, hydroxycarboxylic acid diamide, hydroxycarboxylic acid imide, hydroxycarboxylic acid diimide, hydroxycarboxylic acid ester amide, hydroxycarboxylic acid ester imide, and hydroxycarboxylic acid imide amide Can do.

  The derivative of hydroxycarboxylic acid can be selected from the group consisting of hydroxycarboxylic acid imide, hydroxycarboxylic acid diimide, hydroxycarboxylic acid ester imide, and hydroxycarboxylic acid imide amide.

  The derivative of hydroxycarboxylic acid can be selected from the group consisting of hydroxycarboxylic acid imides and hydroxycarboxylic acid diimides.

  The derivative of hydroxycarboxylic acid can be a derivative of tartaric acid, an imide derivative of citric acid, or a mixture thereof.

  The derivative of hydroxycarboxylic acid can be an imide derivative of tartaric acid, an imide derivative of citric acid, or a mixture thereof.

  In one embodiment, the hydroxycarboxylic acid derivative is an ester or imide. The ester derivative of hydroxycarboxylic acid can be a tartrate ester. The imide derivative of hydroxycarboxylic acid can be tartarimide.

  In one embodiment, the derivative of hydroxycarboxylic acid (or a compound derived from hydroxycarboxylic acid) can be an imide derivative of hydroxycarboxylic acid.

  U.S. Patent Application No. 60/939949 (filed May 24, 2007), now WO 2008/147704, and U.S. Patent Application No. 60 / (filed May 24, 2007). 939952, now WO 2008/147700, discloses suitable hydroxycarboxylic acid compounds and methods for their preparation.

  Canadian Patent No. 1183125, US Patent Application Publication No. 2006/0183647, US Patent Application Publication No. 2006-0079413, US Patent Application No. 60/867402 (now International Publication No. 2008/0667259) and British Patent No. 2105743. All issues A disclose examples of suitable tartaric acid derivatives.

  In one embodiment, the amide, ester or imide derivative of a hydroxycarboxylic acid can be represented by formula (1) (ie, 1a or 1b).

Where
n ′ is 0 to 10 in the formula (1b), 1 to 10 in the formula (1a),
p is 1 to 5,
Y and Y ′ are each independently —O—,>NH,> NR ³ , or both Y and Y ′ groups in (1b) or two Y groups in (1a) together. An imide group formed by forming a R ¹ —N <group between the> C═O groups of

X is _{^{independently, -CH 2 -,> CHR 4}} ,> CR 4 R 5,> CHOR 6,> C (OH) CO 2 R 6,> C (CO 2 R 6) 2, -CH 3, -CH ₂ R ⁴ or CHR ⁴ R ⁵ , —CH ₂ OR ⁶ , —CH (CO ₂ R ⁶ ) ₂ , ≡C—R ⁶ (where ≡ is equal to the trivalence and applies only to formula (1a)) Or a mixture thereof and satisfying the valence of formula (1a) and / or (1b) (typically the compound of formula (1a) or (1b) contains at least a hydroxyl Having one X (ie,> CHOR ⁶ , where R ⁶ is hydrogen).
R ¹ and R ² are independently hydrocarbyl groups, typically containing 1 to 150, or 4 to 30, or 8 to 15 carbon atoms;
R ³ is a hydrocarbyl group;
R ⁴ and R ⁵ are independently keto-containing groups (such as acyl groups), ester groups or hydrocarbyl groups, or —OR ⁶ , or —CO ₂ R ⁶ , or —OH (typically X is> CR ⁴ R ⁵ is one or less —OH),
R ⁶ is independently a hydrogen or hydrocarbyl group typically containing 1 to 150, or 4 to 30, or 8 to 15 carbon atoms.

In one embodiment, the compound of formula (1) contains an imide group. An imide group is typically formed by the Y and Y ′ groups taken together to form a R ¹ —N <group between two> C═O groups.

In one embodiment, the compound of formula (1) has m, n, X, and R ¹ , R ² and R ⁶ defined as follows: That is, m is 0 or 1, n is 1 to 2, X is> CHOR ⁶ and R ¹ , R ² and R ⁶ are independently hydrocarbyl groups containing 4 to 30 carbon atoms. is there.

  In one embodiment, both Y and Y 'are -O-.

In one embodiment, the compound of formula (1) has m, n, X, Y, Y ′ and R ¹ , R ² and R ⁶ defined as follows: That is, m is 0 or 1, n is 1 to 2, X is> CHOR ⁶ , Y and Y ′ are both —O—, and R ¹ , R ² and R ⁶ are independently , Hydrogen, or a hydrocarbyl group containing 4 to 30 carbon atoms.

Diesters, diamides, esteramides, and esterimide compounds of formula (1) may be prepared by reacting a dicarboxylic acid (such as tartaric acid) with an amine or alcohol, optionally in the presence of a known esterification catalyst. it can. In the case of an esterimide compound, it is necessary to have at least three carboxylic acid groups (such as citric acid). The amine or alcohol typically has enough carbon atoms to meet the requirements of R ¹ and / or R ² defined by formula (1).

In one embodiment, R ¹ and R ² are independently straight chain or branched hydrocarbyl groups. In one embodiment, the hydrocarbyl group is branched. In one embodiment, the hydrocarbyl group is linear. R ¹ and R ² can be incorporated into formula (1) by an amine or alcohol. Alcohol includes both monohydric alcohols and polyhydric alcohols. The carbon atom of the alcohol can be linear, branched or a mixture thereof.

  Examples of suitable branched alcohols include 2-ethylhexanol, isotridecanol, Guerbet alcohol or mixtures thereof.

  Examples of monohydric 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 5 to 20 carbon atoms.

  The alcohol includes either a monohydric alcohol or a polyhydric alcohol. Examples of suitable polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, sorbitol, pentaerythritol , Trimethylolpropane, starch, glucose, sucrose, methylglucoside or mixtures thereof. In one embodiment, the polyhydric alcohol is used in a mixture with the monohydric alcohol. Typically in such combinations, the monohydric alcohol comprises at least 60 mole percent, or at least 90 mole percent of the mixture.

  The tartaric acid used in the preparation of the tartaric acid esters of the present invention can be commercially available, depending on the (natural) source or the synthesis method (from maleic acid), often d-tartaric acid, l-tartaric acid, d, It may exist as one or more isomers such as l-tartaric acid or mesotartaric acid. For example, a racemic mixture of d-tartaric acid and l-tartaric acid is obtained from the catalytic oxidation of maleic acid with hydrogen peroxide (using a tungstic acid catalyst). These derivatives can also be prepared from diacids and functional equivalents that are readily understood by those skilled in the art, such as esters, acid chlorides, and acid anhydrides.

  When the compound of formula (1) is derived from tartaric acid, the resulting tartaric acid ester can be a solid, semi-solid or liquid oil, depending on the particular alcohol used in the preparation of the tartaric acid ester. When used as an additive in a lubricating composition, the tartaric acid ester is advantageously soluble in such an oily composition and / or can be stably dispersed. For example, a composition intended for use in oil is typically soluble and / or stably dispersed in the oil in which it is used. As used herein and in the appended claims, the term “soluble in oil” does not necessarily mean that all of the compositions are miscible or soluble in all oils in any proportion. Rather, to the extent that the solution can exhibit one or more of the desired properties, the composition is formulated in an oil (mineral oil, synthetic oil, etc.) or formulated lubrication for which it is intended to function. It shall mean that it is soluble in the agent. Similarly, such “solutions” need not be true solutions in a strict physical or chemical sense. Instead, such “solutions” are, in the present invention, microemulsions or colloids that exhibit properties that closely approximate the properties of the true solution so that they are actually compatible with the true solution in the context of the present invention. It can be a dispersed dispersion.

  A derivative of hydroxycarboxylic acid (or a compound derived from hydroxycarboxylic acid) is 0.1% to 5%, or 0.2% to 3%, or more than 0.2% by weight of the lubricating composition. To 3% by weight in the lubricating composition.

Phosphate Amine Salt In one embodiment, the lubricating composition further comprises a phosphate ester amine salt. The phosphoric acid utilized in the preparation of the phosphate ester amine salt can be either phosphoric acid or thiophosphoric acid.

  The amine salt of the phosphate ester can comprise ester groups having 1 to 30, 6 to 30, 8 to 30, 10 to 24 or 12 to 20, or 16 to 20 carbon atoms, respectively. However, some or all of the ester groups are long enough to dissolve the amine salt of the phosphate ester in the oil of lubricating viscosity. Typically, ester groups containing 4 or more carbon atoms are particularly useful.

  Examples of suitable ester groups include isopropyl, methylamyl (which may also be referred to as 1,3-dimethylbutyl), 2-ethylhexyl, heptyl, octyl, nonyl, decyl, dodecyl, butadecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, Eicosyl or a mixture thereof may be mentioned.

  In one embodiment, the ester group is selected from the group consisting of isopropyl, methylamyl (which may also be referred to as 1,3-dimethylbutyl), 2-ethylhexyl, heptyl, octyl, nonyl, decyl and mixtures thereof.

  Amines that may be suitable for use as amine salts include primary amines, secondary amines, tertiary amines and mixtures thereof. Amines include amines having at least one hydrocarbyl group or, in some embodiments, two or three hydrocarbyl groups. The hydrocarbyl group can contain 2 to 30 carbon atoms, and in another embodiment can contain 8 to 26, or 10 to 20, or 13 to 19 carbon atoms.

  Primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine and dodecylamine, and n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecyl. Examples of amines, n-octadecylamine and oleamine are linear amines. Other useful fatty amines include “Armeen®” amines (available from Akzo Chemicals, Chicago, Illinois, such as Armeen C, Armeen O, Armeen OL, Armeen T, Armeen HT, Armeen S, and Armeen SD. Commercial fatty amines such as Here, the character name relates to an aliphatic group such as palm, oleyl, tallow, and stearyl groups.

  Examples of suitable secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine, ethylamylamine, dicocoamine and di-2-ethylhexylamine Is mentioned. The secondary amine can be a cyclic amine such as piperidine, piperazine, and morpholine.

  The amine can also be a tertiary aliphatic primary amine. The aliphatic group in this case can be an alkyl group containing 2 to 30, or 6 to 26, or 8 to 24 carbon atoms. Tertiary alkylamines include tert-butylamine, tert-hexylamine, 1-methyl-1-amino-cyclohexane, tert-octylamine, tert-decylamine, tert-dodecylamine, tert-tetradecylamine, tert-hexa Examples include monoamines such as decylamine, tert-octadecylamine, tert-tetracosanylamine, and tert-octacosanylamine.

The amine salt of the ester of phosphoric acid can be the reaction product of a C _12-20 alkyl phosphoric acid and a tertiary C _11-22 alkyl primary amine.

  In one embodiment, the amine salt of the phosphate ester comprises an amine having a C11-C14 tertiary alkyl primary amino group or a mixture thereof. In one embodiment, the amine salt of the phosphorus compound comprises an amine having a C14-C18 tertiary alkyl primary amine or a mixture thereof. In one embodiment, the amine salt of the phosphorus compound comprises an amine having a C18-C22 tertiary alkyl primary amine or a mixture thereof.

  In one embodiment, the amine salt of a phosphate ester includes the reaction product of octadecenyl phosphate and Primene 81R ™.

  Mixtures of amines can also be used in the present invention. In one embodiment, useful amine mixtures are “Primene ™ 81R” and “Primene ™ JMT”. Primene ™ 81R and Primene ™ JMT (both manufactured and sold by Rohm & Haas) are a mixture of C11-C14 tertiary alkyl primary amine and C18-C22 tertiary alkyl primary, respectively. It is a mixture of primary amines.

  In one embodiment, the amine salt of the phosphate ester is the reaction product of C14-C18 alkylated phosphoric acid and Primene 81R ™, which is a mixture of C11-C14 tertiary alkyl primary amines. .

  Examples of amine salts of phosphoric acid esters include isopropyldithiophosphoric acid, methylamyldithiophosphoric acid (1,3-dimethylbutyldithiophosphoric acid or a mixture thereof), 2-ethylhexyldithiophosphoric acid, heptyldithiophosphoric acid, octyldithiophosphoric acid, nonyldithiophosphoric acid Or the reaction product (s) of decyldithiophosphoric acid and ethylenediamine, morpholine or Primene 81R ™, and mixtures thereof.

  Examples of amine salts of phosphate esters include tetradecyl dithiophosphoric acid, pentadecyl dithiophosphoric acid, hexadecyl dithiophosphoric acid, heptadecyl dithiophosphoric acid, octadecyl dithiophosphoric acid, nonadecyl dithiophosphoric acid or eicosyl dithiophosphoric acid and ethylenediamine, morpholine or Reaction product (s) with Primene 81R ™ and mixtures thereof. In one embodiment, the amine salt of a phosphate ester includes the reaction product of octadecenyl dithiophosphoric acid and Primene 81R ™.

  In one embodiment, the amine salt of the phosphorous compound comprises (i) a hydroxy-substituted di-ester of phosphoric acid or (ii) a hydroxy-substituted di- or phosphorous of phosphorylated phosphoric acid. It can be an amine salt of either a hydroxy-substituted triester of oxidized phosphoric acid (substituted di-or tri-ester of phosphoric acid). A more detailed description of this type of compound is described in WO2008 / 094759.

  In one embodiment, the amine salt of phosphoric acid is a compound described in US Pat. No. 3,197,405. In one embodiment, amine salts of phosphorus compounds other than those disclosed above can be prepared according to any one of Examples 1 to 25 of US Pat. No. 3,197,405.

  In one embodiment, the amine salt of a phosphorus compound other than those disclosed above is a reaction mixture prepared by reacting dithiophosphoric acid with an epoxide or glycol. This reaction product is further reacted with phosphoric acid, phosphoric anhydride or a lower ester of phosphoric acid (where “lower” is 1 to 8, or 1 to 6, in the portion derived from the alcohol of the ester, Or 1 to 4 or 1 to 2 carbon atoms). Epoxides include aliphatic epoxides or styrene oxide. Examples of useful epoxides include ethylene oxide, propylene oxide, butene oxide, octene oxide, dodecene oxide, styrene oxide, and the like. In one embodiment, the epoxide is propylene oxide. Glycols include aliphatic glycols having 2 to 12, or 2 to 6, or 2 to 3 carbon atoms. Dithiophosphoric acid, glycols, epoxides, inorganic phosphorus reagents and methods of reacting them are described in US Pat. Nos. 3,197,405 and 3,544,465. The resulting acid is then salted with an amine.

  An example of a suitable dithiophosphoric acid product is hydroxypropyl O, O-di (1 prepared by reacting di (1,3-dimethylbutyl) phosphorodithioic acid with 1.3 moles of propylene oxide at 25 ° C. , 3-dimethylbutyl) phosphorodithioate is prepared by adding phosphorus pentoxide (about 64 grams) at 58 ° C. for 45 minutes to 514 grams. The mixture is heated at 75 ° C. for 2.5 hours, mixed with diatomaceous earth and filtered at 70 ° C. The filtrate contains 11.8% by weight phosphorus, 15.2% by weight sulfur and an acid number 87 (bromophenol blue).

  The amine salt of the phosphate ester is 0% to 5%, or 0.01% to 5%, or 0.01% to 2%, or 0.25% to 1% by weight of the lubricating composition. It can be present in weight percent.

Oil of lubricating viscosity The lubricating composition comprises an oil of lubricating viscosity. Such oils include natural and synthetic oils, oils derived from hydrocracking, hydrogenation and hydrofinishing, unrefined, refined and rerefined oils, and mixtures thereof.

  Unrefined oils are those obtained directly from natural or synthetic sources, generally with no (or little) further refining treatment.

  Refined oils are similar to unrefined oils, except that they have been further processed in one or more purification stages to improve one or more properties. Purification techniques are known in the art and include solvent extraction, secondary distillation, acid or base extraction, filtration, and percolation.

  Rerefined oil, also known as reclaimed or reprocessed oil, is obtained by a process similar to the process used to obtain refined oil, and by techniques directed to the removal of spent additives and oil breakdown products. Further, it is often processed.

  Natural oils useful for making the lubricants of the present invention include animal oils (eg lard oil), vegetable oils (eg castor oil), mineral oils (eg liquid petroleum, paraffinic, naphthenic or mixed paraffins). System-naphthenic type solvent-treated or acid-treated mineral oil-based lubricants), as well as oils derived from coal or shale, or mixtures thereof.

  Synthetic lubricating oils are useful, polymerized olefins and interpolymerized olefins (eg, polybutylene, polypropylene, propylene isobutylene copolymers); poly (1-hexene), poly (1-octene), poly (1-decene) and its Mixtures; alkylbenzenes (eg dodecylbenzene, tetradecylbenzene, dinonylbenzene, di (2-ethylhexyl) benzene); polyphenyls (eg biphenyl, terphenyl, alkylated polyphenyl); alkylated diphenyl ethers and alkylated diphenyl sulfides And hydrocarbon oils such as derivatives, analogs and homologues thereof, or mixtures thereof.

  Other synthetic lubricating oils include polyol esters (such as Priolube® 3970), diesters, liquid esters of phosphorus-containing acids (eg, tricresyl phosphate, trioctyl phosphate, and diethyl ester of decanephosphonic acid), or Polymerized tetrahydrofuran may be mentioned. Synthetic oils can be produced by the Fischer-Tropsch reaction and can typically be hydroisomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, the oil can be prepared by a Fischer-Tropsch gas-to-liquid synthesis procedure, as can other gas-to-liquid (GTL) oils.

  Oils of lubricating viscosity can also be defined as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. The five base oil groups are as follows: Group I (sulfur content> 0.03% by weight and / or <90% by weight saturation, viscosity index 80-120), Group II (sulfur content ≦ 0. 03 wt% and ≧ 90 wt% saturation, viscosity index 80-120), Group III (sulfur content ≦ 0.03% wt and ≧ 90 wt% saturation, viscosity index ≧ 120), group IV (all polyalpha Olefin (PAO)), and Group V (all others not included in Group I, II, III or IV). Oils of lubricating viscosity include API Group I oil, API Group II oil, API Group III oil, API Group IV oil, API Group V oil or mixtures thereof. Oils of lubricating viscosity are often API Group I oils, API Group II oils, API Group III oils, API Group IV oils or mixtures thereof. Alternatively, the oil of lubricating viscosity is often API Group II oil, API Group III oil or API Group IV oil or mixtures thereof.

  The amount of oil of lubricating viscosity present is typically the remainder of the total amount of borated phospholipid, amine salt of phosphate ester and other performance additives subtracted from 100% by weight. is there.

  The lubricating composition may be in the form of a concentrate and / or a fully formulated lubricant. Components of the lubricating composition when the lubricating composition disclosed herein is in the form of a concentrate (which can be combined, in whole or in part, to form a complete lubricant) with additional oil The ratio of oil to lubricating oil and / or diluent oil includes the range of 1:99 to 99: 1 by weight or 80:20 to 10:90 by weight. When in the form of a concentrate, the present invention can be part of a complete lubricant composition, and can be an auxiliary additive package or “top treat”.

Other Performance Additives The composition of the present invention optionally further comprises at least one other performance additive. Other performance additives include dispersants, metal deactivators, cleaning agents, viscosity modifiers, (typically boron and / or sulfur and / or phosphorus) extreme pressure agents, antiwear agents. , Antioxidants (such as hindered phenols, amine-based antioxidants, or molybdenum compounds), corrosion inhibitors, foam suppressors, demulsifiers, pour point depressants, seal swelling agents, friction modifiers and mixtures thereof. It is done.

  The total amount of other performance additives (other than viscosity modifiers) present on an oil-free basis is 0% to 25%, or 0.01% to 20%, or 0. A range of 1% to 15%, or 0.5% to 10%, or 1 to 5% by weight can be included. One or more other performance additives may be present, but the other performance additives are generally present in amounts different from each other.

  In one embodiment, the lubricating composition does not include a molybdenum-containing additive.

Viscosity modifier In one embodiment, the lubricating composition further comprises one or more viscosity modifiers.

  When present, the viscosity modifier is in an amount of 0.5% to 70%, 1% to 60%, or 5% to 50%, or 10% to 50% by weight of the lubricating composition. Can exist in

  Viscosity modifiers include (a) polymethacrylate, (b) (i) vinyl aromatic monomers and (ii) unsaturated carboxylic acids, acid anhydrides, or derivatives thereof, (c) (i ) An alpha-olefin and (ii) an ester-type interpolymer of an unsaturated carboxylic acid, acid anhydride, or derivative thereof, or (d) a hydrogenated copolymer of styrene-butadiene, (e) an ethylene-propylene copolymer, (f) polyisobutene, (G) hydrogenated styrene-isoprene polymer, (h) hydrogenated isoprene polymer, or (i) mixtures thereof.

  In one embodiment, the viscosity modifier includes (a) polymethacrylate, (b) (i) a vinyl aromatic monomer and (ii) an ester-type copolymer of an unsaturated carboxylic acid, acid anhydride or derivative thereof, ( c) ester-type interpolymers of (i) alpha-olefins and (ii) unsaturated carboxylic acids, acids, anhydrides or derivatives thereof, or (d) mixtures thereof.

Extreme Pressure Agent Examples of extreme pressure agents include compounds containing boron and / or sulfur and / or phosphorus.

  The extreme pressure agent can be present in the lubricating composition at 0% to 20%, or 0.05% to 10%, or 0.1% to 8% by weight of the lubricating composition.

  In one embodiment, the extreme pressure agent is a sulfur-containing compound. In one embodiment, the sulfur-containing compound can be a sulfurized olefin, a polysulfide, or a mixture thereof.

  Examples of sulfurized olefins include sulfurized olefins derived from propylene, isobutylene, pentene; organic sulfides and / or polysulfides including benzyl disulfides; bis (chlorobenzyl) disulfides; dibutyl tetrasulfides; ditertiary butyl polysulfides; Sulfurized methyl ester of oleic acid, sulfurized alkylphenol, sulfurized dipentene, sulfurized terpene, sulfurized Diels-Alder adduct, alkylsulfenyl N′N-dialkyldithiocarbamate; or a mixture thereof. In one embodiment, the sulfurized olefin includes a sulfurized olefin derived from propylene, isobutylene, pentene, or mixtures thereof.

  In one embodiment, the extreme pressure agent sulfur-containing compound includes dimercaptothiadiazole or a derivative or mixture thereof. Examples of dimercaptothiadiazole include 2,5-dimercapto-1,3,4-thiadiazole or hydrocarbyl substituted 2,5-dimercapto-1,3,4-thiadiazole or oligomers thereof. Hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole oligomers typically form sulfur-sulfur bonds between 2,5-dimercapto-1,3,4-thiadiazole units to form 2 Formed by forming a derivative or oligomer of more than one said thiadiazole unit. Suitable 2,5-dimercapto-1,3,4-thiadiazole-derived compounds include 2,5-bis (tert-nonyldithio) -1,3,4-thiadiazole or 2-tert-nonyldithio-5-mercapto-1 3,4-thiadiazole.

  The number of carbon atoms on the hydrocarbyl substituent of the hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically comprises 1 to 30, or 2 to 20, or 3 to 16.

  In one embodiment, the extreme pressure agent includes a boron-containing compound. Boron-containing compounds include boric acid esters, borated alcohols, borated dispersants or mixtures thereof (which in some embodiments may also be referred to as borated epoxides). In one embodiment, the boron-containing compound can be a borate ester or a borated alcohol.

  The borate ester can be prepared by reacting a boron compound with at least one compound selected from an epoxy compound, a halohydrin compound, an epihalohydrin compound, an alcohol, and a mixture thereof. Examples of the alcohol include dihydric alcohols, trihydric alcohols, and higher alcohols. However, in one embodiment, the hydroxyl group is on an adjacent carbon atom, ie vicinal.

Suitable boron compounds for the preparation of borate esters include boric acid, boron oxide, boron trioxide (including metaboric acid, HBO ₂ , orthoboric acid, H ₃ BO ₃ and tetraboric acid, H ₂ B ₄ O ₇ ). And various forms selected from the group consisting of alkyl borate. Boric acid esters can also be prepared from boron halides.

  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 compound includes tributyl borate, tri-2-ethylhexyl borate, or mixtures thereof.

  In one embodiment, the boron-containing compound is a borated dispersant, typically derived from an N-substituted long chain alkenyl succinimide. In one embodiment, the borated dispersant includes polyisobutylene succinimide. Borated dispersants are described in more detail in US Pat. No. 3,087,936 and US Pat. No. 3,254,025.

  In one embodiment, the borated dispersant can be used in combination with a sulfur-containing compound or borate ester.

  In one embodiment, the extreme pressure agent is other than a borated dispersant.

  The number average molecular weight of the hydrocarbon derived from the long chain alkenyl group includes a range of 350 to 5000, or 500 to 3000, or 550 to 1500. The number average molecular weight of the long chain alkenyl group can be 550, or 750, or 950 to 1000.

N-substituted long chain alkenyl succinimides include boric acid (eg, metaboric acid, HBO ₂ , orthoboric acid, H ₃ BO ₃ and tetraboric acid, H ₂ B ₄ O ₇ ), boron oxide, boron trioxide and alkyl borate. It is borated using various agents. In one embodiment, the borated agent is boric acid and can be used alone or in combination with another borated agent.

  The borated dispersant blends the boron compound and the N-substituted long chain alkenyl succinimide and mixes it with a suitable amount, such as 80 ° C to 250 ° C, 90 ° C to 230 ° C, 100 ° C to 210 ° C, until the desired reaction occurs. It can be prepared by heating to temperature. The molar ratio of boron compound to N-substituted long chain alkenyl succinimide can range from 10: 1 to 1: 4 or 4: 1 to 1: 3, or the molar ratio of boron compound to N-substituted long chain alkenyl succinimide Can be 1: 2. An inert liquid can be used to carry out the reaction. Examples of the inert liquid include toluene, xylene, chlorobenzene, dimethylformamide, or a mixture thereof.

  Examples of friction modifiers (other than (a) borated phospholipids and (b) phosphate ester amine salts) include fatty amines, esters such as borated glycerol esters, fatty phosphites, fatty acid amides, fatty epoxides, borohydrides. Oxidized fatty epoxides, alkoxylated fatty amines, borated alkoxylated fatty amines, fatty acid metal salts, or fatty imidazolines, condensates of carboxylic acids and polyalkylene-polyamines.

  In one embodiment, the lubricating composition may include a phosphorus-containing antiwear agent or a sulfur-containing antiwear agent other than the compounds described as extreme pressure agents for the amine salt of the phosphate ester. Examples of antiwear agents include nonionic phosphorus compounds (typically compounds having a phosphorus atom in the oxidation state +3 or +5), metal dialkyldithiophosphates (typically zinc dialkyldithiophosphates), Mention may be made of metal monoalkyl phosphates or metal dialkyl phosphates (typically zinc phosphate), or mixtures thereof.

  Nonionic phosphorus compounds include phosphites, phosphates or mixtures thereof. A more detailed description of nonionic phosphorus compounds includes columns 9, 48 to columns 11, 8 of US Patent Application No. 6,103,673.

  In one embodiment, the lubricating composition of the present invention further comprises a dispersant. Dispersants include succinimide dispersants (eg, N-substituted long chain alkenyl succinimides), Mannich dispersants, ester-containing dispersants, condensates of fatty hydrocarbyl monocarboxyl acylating agents with amines or ammonia, alkylaminophenol dispersants, hydrocarbyls -It can be an amine dispersant, a polyether dispersant, or a polyetheramine dispersant.

  In one embodiment, the succinimide dispersant includes a polyisobutylene substituted succinimide, and the polyisobutylene derived from the dispersant may have a number average molecular weight of 400 to 5000, or 950 to 1600.

  Succinimide dispersants and methods for their preparation are described in more detail in US Pat. Nos. 4,234,435 and 3,172,892.

  Suitable ester-containing dispersants are typically high molecular weight esters. These materials are described in more detail in US Pat. No. 3,381,022.

  In one embodiment, the dispersant includes a borated dispersant. Typically, borated dispersants include succinimide dispersants, including polyisobutylene succinimide, and the polyisobutylene derived from the dispersant can have a number average molecular weight of 400 to 5000. The borated dispersant is described in more detail in the extreme pressure description above.

  Dispersant viscosity modifiers (often referred to as DVM) include functional polyolefins such as ethylene-propylene copolymers functionalized with reaction products of maleic anhydride and amines, and amine functionalities. Or an ester-type styrene-maleic anhydride copolymer reacted with an amine can be used in the composition of the present invention.

  Examples of the corrosion inhibitor include 1-amino-2-propanol, octylamine octanoate, dodecenyl succinic acid or acid anhydride, and / or a condensate of a polyamine and a fatty acid such as oleic acid.

  Metal deactivators include derivatives of benzotriazole (typically tolyltriazole), 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole or 2-alkyldithiobenzothiazole. Metal deactivators can also be described as corrosion inhibitors.

  Antifoaming agents include copolymers of ethyl acrylate and 2-ethylhexyl acrylate, and optionally vinyl acetate.

  Demulsifiers include trialkyl phosphates and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide or mixtures thereof.

  Maleic anhydride-pour point depressants including styrene, polymethacrylate, polyacrylate or polyacrylamide.

  Seal swelling agents including Exxon Necton-37 ™ (FN1380) and Exxon Mineral Seal Oil ™ (FN3200).

Industrial Applications Limited slip differentials typically incorporate a self-contained lubricant supply that is separate from the lubricant disposed in the differential housing or carrier. The limited slip differential built-in lubricant is generally different from the lubricant supplied to the manual transmission fluid or the automatic transmission fluid. In both manual and automatic transmission systems that do not include a limited slip differential, one type of lubricant is typically sufficient to lubricate all of the transmission components.

  The axle gear can have any one of many different types of differentials. A differential typically has three main functions. The first function is to transmit engine power to the wheels. The second function acts as a final gear reduction of the automobile and reduces the rotational speed from the transmission to the wheels. The third function is to transmit output to the wheel while rotating the wheel at different speeds. Many differentials are known and include open differentials, clutch-type limited slip differentials, viscous coupling differentials, Torsen differentials and locking differentials. All of these differentials can be collectively referred to as axle gears.

  Axle gears typically require a lubricant. The lubricant formulation depends on the type of axle gear and the operating conditions of the axle gear. For example, open differential axle gears may require antiwear and / or extreme pressure additives. In contrast, limited slip differentials typically require a friction modifier. This is because, in addition to open differentials (known from numerous axle fluids), there are typically spring packs and clutch packs. The clutch pack can include one or more reaction plates (often made of steel) and one or more friction plates. Friction plates are well known and can be made from many materials including paper, carbon, graphite, steel and composites.

  Suitable sulfur compositions for limited slip differentials have a sulfur content of 0.3% to 5%, or 0.5% to 5%, or 0.5% to 3%, or 0. It can range from 8% to 2.5% by weight, or from 1% to 2% by weight.

  In one embodiment, a suitable lubricating composition for a limited slip differential can be a fully formulated fluid.

  In one embodiment, a suitable lubricating composition for a limited slip differential can be a top treatment concentrate.

  When the lubricating composition is in the form of a top treatment concentrate, the concentrate is from 0.2 wt% to 10 wt%, or from 0.5 wt% to 7 wt%, based on the amount of lubricant in the limited slip differential. Can be added.

  The following examples illustrate the invention. These examples are not exhaustive and do not limit the scope of the invention.

Example 1 (EX1) : 1271 g of commercially available slip limited axle fluid is top treated with 1.74 wt% oleyl tartarimide.

Comparative Example 1 (CE1) is the same commercial axle fluid as EX1, except that oleyl tartarimide is not added.

The prepared examples (EX1 and CE1) are evaluated on a Low Speed SAE # 2 tester by mu-PVT (friction coefficient mu obtained at different pressures, speeds and temperatures) friction screening test. This friction screening test is based on Miba (S-F-S-F-S-F-S-F-S, where S is a steel plate and F is a friction plate) with the following plate structure: Utilizes a Dana (TM) model 80 plate structure with a MC-631 friction material, thereby creating eight active friction surfaces. The test is performed with different pressurization and plate differential speed diagrams while keeping the temperature constant at 50 ° C. There are six pressure settings of 190, 380, 570, 760, 950 and 1075 kPa. For each pressurization setting, four different plate differential speeds of 15, 50, 85 and 120 rpm are used. At each plate differential speed, 25 repeat cycles are performed. Each test is a total of 600 cycles (6 pressures x 4 speeds x 25 cycles). A 600 cycle mu-PVT or friction diagram is performed before and after the endurance cycle to evaluate the change in friction performance. The endurance cycle consists of a constant pressure of 570 kPa at a fluid temperature of 80 ° C. and a repetition of a plate differential speed of 120 to 0 rpm. One complete cycle consists of 5 seconds at 0 rpm and 5 seconds at 120 rpm. This is repeated for a total of 2500 cycles. The primary measurement is the NVH rating, which indicates the change in torque signal during an individual speed event, or the difference between the minimum and maximum coefficient of friction obtained during the event. This measurement assigns a numerical value to the magnitude of the torque signal change according to the following table.
Torque signal change NVH rating 0 to 0.02 friction coefficient unit 0
Coefficient of friction unit from 0.02 to 0.04 1
Coefficient of friction unit of 0.04 to 0.06 2
Coefficient of friction unit from 0.06 to 0.08 3
Coefficient of friction unit from 0.08 to 0.10 4
Friction coefficient unit from 0.10 to 0.12 5
Coefficient of friction unit from 0.12 to 0.14 6
Friction coefficient units from 0.14 to 0.16 7
These scores are summed for all cycles completed at one pressurization and speed setting and then for the entire test. The maximum NVH score is 9600 points (6 pressure × 4 speed × 25 repetitions × 8 NVH score = 4800, before and after durability evaluation × 2 = 9600). This is considered as extremely low friction performance. The minimum NVH score is 0 points. This is considered excellent friction performance. The NV1 score after endurance of EX1 is 152 and CE1 is 565. The total NVH score for EX1 and CE1 is 471 and 728, respectively.

  According to the data obtained from the tests, the lubricating composition of the present invention can provide a limited slip differential having a low tendency to post-endurance NVH, which often appears as chatter.

  It is known that some of the materials can interact in the final formulation, and each component of the final formulation can be different from the components added initially. The product formed thereby may not be easily described, including the product formed by using the lubricant composition of the present invention for its intended use. Nonetheless, all such modifications and reaction products are included within the scope of the present invention, which includes a lubricant composition prepared by mixing the above components.

  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 bonded directly to the rest of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:

(I) Hydrocarbon substituents, ie aliphatic (eg alkyl or alkenyl) substituents, alicyclic (eg cycloalkyl, cycloalkenyl) substituents, aromatic-, aliphatic- and alicyclic-substituted Aromatic substituents, as well as cyclic substituents in which the ring is completed via another part of the molecule (eg, two substituents together form a ring);
(Ii) Substituted hydrocarbon substituents, ie, substituents containing non-hydrocarbon groups that do not alter the predominantly hydrocarbon nature of the substituent (eg, halo (especially chloro and fluoro), hydroxy, Alkoxy, mercapto, alkylmercapto, nitro, nitroso and sulfoxy),
(Iii) Hetero substituents, i.e. having predominantly hydrocarbon character, but in the context of the present invention include other than carbon in the ring or chain, the ring or chain being otherwise composed of carbon atoms , Substituents, and (iv) heteroatoms include sulfur, oxygen, nitrogen, and include substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more than 2, preferably no more than 1 non-hydrocarbon substituent will be present for every 10 carbon atoms in the hydrocarbyl group, and typically there will be no non-hydrocarbon substituents in the hydrocarbyl group. .

  Each of the documents referred to above is incorporated herein by reference. It should be understood that all quantities specifying quantities such as materials, reaction conditions, molecular weight, number of carbon atoms, etc. in this description are modified by the word “about” unless otherwise stated or otherwise indicated. is there. Unless otherwise stated, each chemical or composition referred to herein should be construed as a commercial grade material and typically present in isomers, by-products, derivatives, and commercial grades. May include other such materials to be understood. However, the amount of each chemical component is indicated except for any solvent or diluent oil that may customarily be present in commercially available materials, unless otherwise stated. It should be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention can be used together with ranges or amounts for any of the other elements.

  Although the present invention has been described with reference to preferred embodiments thereof, it should be understood that various modifications thereof will become apparent to those skilled in the art upon reading this specification. Accordingly, it is to be understood that the invention disclosed herein is intended to embrace such modifications that fall within the scope of the appended claims.

Claims (19)

A method of lubricating the limited slip differential comprising supplying a lubricating composition comprising (a) a hydroxycarboxylic acid derivative and (b) an oil of lubricating viscosity to the limited slip differential,
The hydroxycarboxylic acid derivative has the formula ( 1a ):

(Where
n 'is 1 to 10 in the formula (1a),
p is 1 to 5,
Y forms a Lee bromide group by forming an ^R 1 -N <group between two> C = O group together the two Y groups in (1a),
X is _{^{independently, -CH 2 -,> CHR 4}} ,> CR 4 R 5,> CHOR 6,> C (OH) CO 2 R 6,> C (CO 2 R 6) 2, -CH 3, -CH ₂ R ⁴ or _{^{-CHR 4 R 5, -CH 2 oR}} 6, -CH (CO 2 R 6) 2, ≡C-R 6 ( wherein, ≡ is not equal to 3 valence), or mixtures thereof Yes, satisfying the valence of formula (1a ) (typically the compound of formula (1a ) has at least one X containing hydroxyl (ie> CHOR ⁶ , where R ⁶ is hydrogen ))),
R ¹ is independently a hydrocarbyl group typically containing 1 to 150, or 4 to 30, or 8 to 15 carbon atoms ;
R ⁴ and R ⁵ are independently a keto-containing group, an ester group or a hydrocarbyl group, or —OR ⁶ , or —CO ₂ R ⁶ , or —OH;
R ⁶ is independently a hydrogen or hydrocarbyl group typically containing 1 to 150, or 4 to 30, or 8 to 15 carbon atoms. )
The method represented by   The method according to claim 1, wherein the derivative of hydroxycarboxylic acid is a derivative of hydroxypolycarboxylic acid. Wherein said derivative of a hydroxy polycarboxylic acid, hydroxy carboxylic acid imide, hydroxy carboxylic acid diimide, is selected from the group consisting of hydroxycarboxylic acid esters imide and Imidoamido hydroxycarboxylic acids, the method described in 請 Motomeko 2. Wherein said derivative of a hydroxy polycarboxylic acid is selected from the group consisting of hydroxy carboxylic acid imide and hydroxycarboxylic acid diimide A method according to any of claims 2 3 preceding. The method according to any one of claims 2 to 4 , wherein the derivative of hydroxypolycarboxylic acid is a derivative of tartaric acid, an imide derivative of citric acid, or a mixture thereof. Derivatives of the hydroxy polycarboxylic acids, imide derivatives of tartaric acid, imide derivatives of citric acid, or mixtures thereof, The method according to any one of claims 2 to 5 the preceding. The method according to any one of claims 2 to 6 , wherein the derivative of hydroxypolycarboxylic acid is an imide derivative of tartaric acid or a mixture thereof. Wherein said derivative of a hydroxy carboxylic acid is present in an amount ranging from 0.1% to 5% by weight of said lubricating composition, method of any of claims 1 to 7, the preceding. 9. A method according to any one of the preceding claims, wherein the hydroxycarboxylic acid derivative is present in an amount ranging from 0.2% to 3% by weight of the lubricating composition. 9. The method of claim 8, wherein the hydroxycarboxylic acid derivative is present in an amount ranging from greater than 0.2% to 3% by weight of the lubricating composition. Further comprising a method according to any one of claims 1 to 10, preceding a sulfur-containing compound. It said sulfur-containing compound is a dimercaptothiadiazole or derivative, or a mixture thereof The method of claim 1 1. It said sulfur-containing compound is a polysulfide or sulfurized olefins, The method of claim 1 1. The lubricating composition further comprises a phosphorus-containing compound, the phosphorus-containing compound is an amine salt of a phosphoric acid ester, A method according to any one of claims 1 1 3 preceding. The amine salt of the phosphate ester is an amine that is either (i) a hydroxy-substituted diester of phosphoric acid or (ii) a hydroxy-substituted diester of phosphorylated phosphoric acid or a hydroxy-substituted triester of phosphorylated phosphoric acid salts a process according to claim 1 4. The lubricating composition further comprises a boron-containing compound, the boron-containing compound, a borated dispersant, a boric acid ester or boric oxide phospholipid A method according to any of claims 1 1 5 the preceding.   The method of claim 1, wherein the hydroxycarboxylic acid comprises a monohydroxymonocarboxylic acid. The method of claim 15 , wherein the monohydroxymonocarboxylic acid comprises glycolic acid.   The method of claim 1, wherein the derivative of hydroxycarboxylic acid is an amide.