WO2007121205A2

WO2007121205A2 - Hydroxy-containing tertiary amines as friction modifiers for automatic transmission fluids

Info

Publication number: WO2007121205A2
Application number: PCT/US2007/066371
Authority: WO
Inventors: Craig D. Tipton; Mark R. Baker; Shreyasi Lahiri; William D. Abraham; Richard J. Vickerman; Suzanne M. Patterson
Original assignee: Lubrizol Corp
Current assignee: Lubrizol Corp
Priority date: 2006-04-12
Filing date: 2007-04-11
Publication date: 2007-10-25
Anticipated expiration: 2008-10-12
Also published as: CA2648664A1; WO2007121205A3; JP2009533536A; CN101421380A; JP5337019B2; EP2010632A2; CA2648664C; EP2010632B1; CN101421380B

Abstract

A composition of a major amount of an oil of lubricating viscosity; a secondary or tertiary amine being represented by the formula R1R2NR3 wherein R1 and R2 are alkyl groups of at least 6 carbon atoms and R3 is hydrogen, a hydrocarbyl group, a hydroxyl-containing alkyl group, or an amine-containing alkyl group; and a dispersant, provides high static coefficients of friction and a durable positive slope during oxidative and mechanical stressing, particularly as a friction component of an automatic transmission.

Description

TITLE HYDROXY-CONTAINING TERTIARY AMINES AS FRICTION MODIFIERS

FOR AUTOMATIC TRANSMISSION FLUIDS BACKGROUND OF THE INVENTION

[0001] The present invention relates to the field of additives for fluids such as automatic transmission fluids, traction fluids, fluids for continuously variable transmission fluids (CVTs), dual clutch automatic transmission fluids, farm tractor fluids, and engine lubricants. [0002] In the automatic transmission marketplace, where there is rapid engineering change driven by the desire to reduce weight and increase transmission capacity, there is a desire for automatic transmission fluids that exhibit a high static coefficient of friction for improved clutch holding capacity. At the same time, there is a desire to improve the retention of positive slope character- istics in the μ/v (coefficient of friction vs. sliding speed) curve. There are newer tests in the marketplace which are used to define these characteristics. The static torque can be measured in tests such as the Toyota SAE#2 friction test procedure and the retention of positive slope can be measured by procedures like the JASO LVFA (Japan Automotive Standards Organization, Low Velocity Friction Apparatus) in which the slope of the μ/v curve is periodically measured during oxidative and mechanical aging.

[0003] There are patents, for example, US 5,750,476, where a type of friction modifier technology used to achieve this performance is described. The combined requirements of high static coefficient of friction and durable positive slope are often incompatible with traditional ATF friction modifier technology which is extremely well described in the patent literature. Many of the commonly used friction modifiers result in a low static coefficient of friction and are not durable enough on positive slope to be of sufficient use. Additional patent literature describing technology for retaining positive mu/v or anti-shudder characteristics include US 5,858,929. These may employ metal detergents and combinations of friction modifiers.

[0004] PCT Publication WO04/007652, Adams et al, January 22, 2004, discloses a fluid composition of (a) a friction modifier derived from the reaction of a carboxylic acid with an amino alcohol, the friction modifier containing at least two hydrocarbyl groups, and (b) a dispersant, which provides good friction properties in an automatic transmission. [0005] U.S. Patent 4,886,612 discloses a lubricating oil comprising at least one of various products, which can be various imidazolines or an oxazoline of the structure

I I

0 - CH₂ where R₂ and R₃ each represent CH₂OCORi, CH₂OH or H, prepared by the condensation a carboxylic acid (or a reactive equivalent thereof) with an amino alcohol; for example, the condensation of two moles of isostearic acid with one mole of tris-hydroxymethylaminomethane (THAM).

[0006] The present invention solves the problem of developing new and relatively simple and inexpensive friction modifiers to obtain high static coefficients of friction and maintain a durable positive slope during oxidative and mechanical stressing of the friction system, particularly for use in an automatic transmission. This is accomplished by the use of a friction modifier which comprises a tertiary amine having at least two alkyl groups of at least 6 carbon atoms, as further described below.

SUMMARY OF THE INVENTION [0007] The present invention provides a composition suitable for lubricating a transmission, comprising:

(a) a major amount of an oil of lubricating viscosity;

(b) a tertiary amine being represented by the formula

R¹R²NR³ wherein R¹ and R² are each independently an alkyl group of at least 6 carbon atoms and R is a polyhydroxyl-containing alkyl group or a polyhydroxyl- containing alkoxy alkyl group; and

(c) a dispersant.

[0008] The present invention further provides a method for lubricating a transmission, comprising supplying thereto the above composition. [0009] The present invention further provides a concentrate suitable for dilution with oil of lubricating viscosity to prepare a lubricant for a transmission, comprising (a) a concentrate-forming amount of an oil of lubricating viscosity; (b) a tertiary amine as described above; and (c) a dispersant. DETAILED DESCRIPTION OF THE INVENTION [0010] Various preferred features and embodiments will be described below by way of non-limiting illustration. [0011] One component of the present invention is an oil of lubricating viscosity, which can be present in a major amount, for a lubricant composition, or in a concentrate forming amount, for a concentrate. Suitable oils include natural and synthetic lubricating oils and mixtures thereof. In a fully formulated lubricant, the oil of lubricating viscosity is generally present in a major amount (i.e. an amount greater than 50 percent by weight). Typically, the oil of lubricating viscosity is present in an amount of 75 to 95 percent by weight, and often greater than 80 percent by weight of the composition. For concentrates, the oil of lubricating viscosity may be present at lower concentration or in a minor amount, for example, from 10 to 50% by weight, and in one embodiment 10 to 30% by weight.

[0012] Natural oils useful in making the inventive lubricants and functional fluids include animal oils and vegetable oils as well as mineral lubricating oils such as liquid petroleum oils and solvent-treated or acid-treated mineral lubri- eating oils of the paraffinic, naphthenic or mixed paraffinic/-naphthenic types which may be further refined by hydrocracking and hydrofinishing processes. [0013] Synthetic lubricating oils include hydrocarbon oils and halo- substituted hydrocarbon oils such as polymerized and interpolymerized olefins, also known as polyalphaolefins; polyphenyls; alkylated diphenyl ethers; alkyl- or dialkylbenzenes; and alkylated diphenyl sulfides; and the derivatives, analogs and homologues thereof. Also included are alkylene oxide polymers and inter- polymers and derivatives thereof, in which the terminal hydroxyl groups may have been modified by esterification or etherification. Also included are esters of dicarboxylic acids with a variety of alcohols, or esters made from C5 to C12 monocarboxylic acids and polyols or polyol ethers. Other synthetic oils include silicon-based oils, liquid esters of phosphorus-containing acids, and polymeric tetrahydrofurans. The synthetic oils may be produced by Fischer-Tropsch reactions and typically may comprise hydroisomerized Fischer-Tropsch hydrocarbons and/or waxes, or hydroisomerized slack waxes. [0014] Unrefined, refined and rerefined oils, either natural or synthetic, can be used in the lubricants of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. Refined oils have been further treated in one or more purification steps to improve one or more properties. They can, for example, be hydrogen- ated, resulting in oils of improved stability against oxidation.

[0015] In one embodiment, the oil of lubricating viscosity is an API Group

II, Group III, Group IV, or Group V oil, including a synthetic oil, or mixtures thereof. These are classifications established by the API Base Oil Interchange- ability Guidelines. Both Group II and Group III oils contain < 0.03 percent sulfur and > 99 percent saturates. Group II oils have a viscosity index of 80 to 120, and Group III oils have a viscosity index > 120. Polyalphaolefins are categorized as Group IV. Group V is encompasses "all others" (except for Group I, which contains > 0.03% S and/or < 90% saturates and has a viscosity index of 80 to 120).

[0016] In one embodiment, at least 50% by weight of the oil of lubricating viscosity is a polyalphaolefin (PAO). Typically, the polyalphaolefins are derived from monomers having from 4 to 30, or from 4 to 20, or from 6 to 16 carbon atoms. Examples of useful PAOs include those derived from 1-decene. These PAOs may have a viscosity of 1.5 to 150 mm²/s (cSt) at 100⁰C. PAOs are typically hydrogenated materials. [0017] The oils of the present invention can encompass oils of a single viscosity range or a mixture of high viscosity and low viscosity range oils. In one embodiment, the oil exhibits a 100⁰C kinematic viscosity of 1 or 2 to 8 or

10 mm²/sec (cSt). The overall lubricant composition may be formulated using

011 and other components such that the viscosity at 100⁰C is 1 or 1.5 to 10 or 15 or 20 mm²/sec and the Brookfield viscosity (ASTM-D-2983) at -4O⁰C is less than 20 or 15 Pa-s (20,000 cP or 15,000 cP), such as less than 10 Pa-s, even 5 or less.

[0018] Component (b) is a tertiary amine, which can serve as a friction modifier. The amine will contain three substituent hydrocarbyl groups, two of which are alkyl groups. The amine is represented by the formula R¹R²NR³ wherein R¹ and R² are each independently an alkyl group of at least 6 carbon atoms (e.g., 8 to 20 carbon atoms or 10 to 18 or 12 to 16) and R³ is a polyhy- droxyl-containing alkyl group or a polyhydroxyl-containing alkoxyalkyl group [0019] In one embodiment the amine comprises a product of di-cocoalkyl amine or homologous amines. Di-cocoalkyl amine (or di-cocoamine) is a secondary amine in which two of the R groups in the above formula are predominantly C i2 groups, derived from coconut oil and the remaining R group is H. [0020] In one embodiment, R is a polyol-containing alkyl group (that is, a group containing 2 or more hydroxy groups) or a group containing one or more hydroxy groups and one or more amine groups. For instance, R³ may be -CH₂- CHOH-CH₂OH or a homologue thereof, containing, for example, 3 to 8 carbon atoms or 3 to 6 carbon atoms or 3 to 4 carbon atoms, and 2, 3, 4 or more hydroxy groups (normally no more than one hydroxy group per carbon atom). A typical resulting product may thus be represented by

R¹R²N-CH₂-CHOH-CH₂OH or homologues thereof, where R¹ and R² are, as described above, independently alkyl groups of 8 to 20 carbon atoms. Such products may be obtained by the reaction of a dialkyl amine with an epoxide or chlorohydroxy compound. In particular, reaction of a secondary amine with glycidol (2,3-epoxy-l-propanol) or "chloroglycerine" (that is, 3-chloropropane-l,2-diol) may be effective under conditions as described above. Such materials based on the reaction of dico- coamine with one or more moles of glycidol or chloroglycerine are particularly useful in providing friction-modifying performance. If reaction is with multiple moles of glycidol or chloroglycerine, or other epoxyalkanols or chlorodiols, a dimeric or oligomeric ether-containing group, that is, a hydroxyl-substituted alkoxyalkyl group, may result.

[0021] The amine, component (b), may alternatively be described, in certain embodiments, as a compound comprising a core portion comprising 3 to 8 carbon atoms, (e.g, 3 to 6, or 3 carbon atoms), said core portion being substituted by: (i) at least two hydroxy groups, or at least one hydroxy group and at least one alkoxy group of 1 to 4 carbon atoms wherein said alkoxy group is further substituted by at least one hydroxy group or another such alkoxy group; and (ii) at least one amino group, the nitrogen atom thereof bearing two hydro- carbyl groups, each such hydrocarbyl group independently having 6 to 30 carbon atoms. [0022] The amount of component (b) in the compositions of the present invention is generally an amount suitable to reduce or inhibit shudder in an automatic transmission, that is, a performance defect observed during wet clutch operation when the friction characteristics of the transmission fluid are inadequately balanced. The effective amount can be 0.01 to 10.0 percent by weight of the finished fluid formulation. Alternative amounts include 0.02 percent to 5 percent, or 0.1 percent to 3 percent, or 0.1 to 2 percent, or 0.5 to 1.5 percent. In a concentrate, the amounts will be proportionately higher.

[0023] Component (c) is a dispersant. It may be described as "other than a species of (b)," in the event that some of the friction modifiers of (b) may exhibit some dispersant characteristics. Examples of "carboxylic dispersants" are described in many U.S. Patents including the following: 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170, 3,467,668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, Re 26,433, and 6,165,235. [0024] Succinimide dispersants, a species of carboxylic dispersants, are prepared by the reaction of a hydro carbyl- substituted succinic anhydride (or reactive equivalent thereof, such as an acid, acid halide, or ester) with an amine, as described above. The hydrocarbyl substituent group generally contains an average of at least 8, or 20, or 30, or 35 up to 350, or to 200, or to 100 carbon atoms. In one embodiment, the hydrocarbyl group is derived from a polyalkene. Such a polyalkene can be characterized by an Mn (number average molecular weight) of at least 500. Generally, the polyalkene is characterized by an Mn of 500, or 700, or 800, or 900 up to 5000, or to 2500, or to 2000, or to 1500. In another embodiment Mn varies from 500, or 700, or 800, to 1200 or 1300. In one embodiment the polydispersity ( Mw /Mn) is at least 1.5. [0025] The polyalkenes include homopolymers and inter-polymers of poly- merizable olefin monomers of 2 to 16 or to 6, or to 4 carbon atoms. The olefins may be monoolefins such as ethylene, propylene, 1-butene, isobutene, and 1- octene; or a polyolefinic monomer, such as diolefinic monomer, such 1,3- butadiene and isoprene. In one embodiment, the inter-polymer is a homo- polymer. An example of a polymer is a polybutene. In one instance about 50% of the polybutene is derived from isobutylene. The polyalkenes can be prepared by conventional procedures.

[0026] In one embodiment, the succinic acylating agents are prepared by reacting a polyalkene with an excess of maleic anhydride to provide substituted succinic acylating agents wherein the number of succinic groups for each equivalent weight of substituent group is at least 1.3, e.g., 1.5, or 1.7, or 1.8. The maximum number of succinic groups per substituent group generally will not exceed 4.5, or 2.5, or 2.1, or 2.0. The preparation and use of substituted succinic acylating agents wherein the substituent is derived from such polyole- fins are described in U.S. Patent 4,234,435. [0027] The substituted succinic acylating agent can be reacted with an amine, including those amines described above and heavy amine products known as amine still bottoms. The amount of amine reacted with the acylating agent is typically an amount to provide a mole ratio of CO:N of 1 :2 to 1 :0.75, . If the amine is a primary amine, complete condensation to the imide can occur. Varying amounts of amide product, such as the amidic acid, may also be present. If the reaction is, rather, with an alcohol, the resulting dispersant will be an ester dispersant. If both amine and alcohol functionality are present, whether in separate molecules or in the same molecule (as in the above-described condensed amines), mixtures of amide, ester, and possibly imide functionality can be present. These are the so-called ester-amide dispersants. [0028] "Amine dispersants" are reaction products of relatively high molecu- lar weight aliphatic or alicyclic halides and amines, such as polyalkylene poly- amines. Examples thereof are described in the following U.S. Patents: 3,275,554, 3,438,757, 3,454,555, and 3,565,804.

[0029] "Mannich dispersants" are the reaction products of alkyl phenols in which the alkyl group contains at least 30 carbon atoms with aldehydes (espe- cially formaldehyde) and amines (especially polyalkylene polyamines). The materials described in the following U.S. Patents are illustrative: 3,036,003, 3,236,770, 3,414,347, 3,448,047, 3,461,172, 3,539,633, 3,586,629, 3,591 ,598, 3,634,515, 3,725,480, 3,726,882, and 3,980,569. [0001] Post-treated dispersants are also part of the present invention. They are generally obtained by reacting at carboxylic, amine or Mannich dispersants with reagents such as urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids, hydro carbon- substituted succinic anhydrides, nitriles, epoxides, boron compounds such as boric acid (to give "borated dispersants"), phosphorus compounds such as phosphorus acids or anhydrides, or 2,5- dimercaptothiadiazole (DMTD). Exemplary materials of this kind are described in the following U.S. Patents: 3,200,107, 3,282,955, 3,367,943, 3,513,093, 3,639,242, 3,649,659, 3,442,808, 3,455,832, 3,579,450, 3,600,372, 3,702,757, and 3,708,422. Other related dispersants include composition comprising the product prepared by heating together: (a) a dispersant as described above and (b) 2,5-dimercapto-l,3,4-thiadiazole or a hydrocarbyl-substituted 2,5-di- mercapto-l,3,4-thiadiazole which is substantially insoluble in a hydrocarbon oil of lubricating viscosity at 25⁰C, and further either (c) a borating agent or (d) an inorganic phosphorus compound, or both (c) and (d), said heating being sufficient to provide a reaction product of (a), (b), and (c) or (d) which is soluble in said hydrocarbon oil at 25⁰C. These materials are described in US Application 2005-0041395.

[0030] Mixtures of dispersants can also be used.

[0031] The amount of component (c) in the compositions of the present invention is generally 0.3 to 10 percent by weight. In other embodiments, the amount of component (c) is 0.5 to 7 percent or 1 to 5 percent of the final blended fluid formulation. In a concentrate, the amounts will be proportionately higher. [0032] Other components which are conventionally employed in a transmission fluid, in particular, and automatic transmission fluid (ATF) are typically also present.

[0033] The functional fluid may contain one or more viscosity modifiers and/or dispersant viscosity modifiers. Viscosity modifiers (VM) and dispersant viscosity modifiers (DVM) are well known. Examples of VMs and DVMs include polymethacrylates, polyacrylates, polyolefins, styrene-maleic ester copolymers, and similar polymeric substances including homopolymers, copolymers and graft copolymers. The DVM may comprise a nitrogen-containing methacrylate polymer, for example, a nitrogen-containing methacrylate polymer derived from methyl methacrylate and dimethylaminopropyl amine. [0034] Examples of commercially available VMs, DVMs and their chemical types include the following: polyisobutylenes (such as Indopol™ from BP Amoco or Parapol™ from ExxonMobil); olefin copolymers (such as Lubrizol™ 7060, 7065, and 7067 from Lubrizol and Lucant™ HC-2000L and HC-600 from Mitsui); hydrogenated styrene-diene copolymers (such as Shellvis™ 40 and 50, from Shell and LZ® 7308, and 7318 from Lubrizol); styrene/maleate copolymers, which are dispersant copolymers (such as LZ® 3702 and 3715 from Lubrizol); polymethacrylates, some of which have dispersant properties (such as those in the Viscoplex™ series from RohMax, the Hitec™ series from Afton, and LZ 7702™, LZ 7727™, LZ 7725™ and LZ 7720C™ from Lubrizol); olefϊn- graft-polymethacrylate polymers (such as Viscoplex™ 2-500 and 2-600 from RohMax); and hydrogenated polyisoprene star polymers (such as Shellvis™ 200 and 260, from Shell). Viscosity modifiers that may be used are described, for instance, in U.S. patents 5,157,088, 5,256,752 and 5,395,539. The VMs and/or DVMs may be used in the functional fluid at a concentration of up to 20% by weight. Concentrations of 1 to 12%, or 3 to 10% by weight may be used. [0035] Another component that may be used in the composition used in the present invention is a supplemental friction modifier. Friction modifiers are well known to those skilled in the art. A useful list of friction modifiers is included in U.S. Pat. No. 4,792,410. U.S. Patent 5,110,488 discloses metal salts of fatty acids and especially zinc salts, useful as friction modifiers. A list of friction modifiers includes:

(i) fatty phosphites (ii) fatty acid amides

(iii) fatty epoxides (iv) borated fatty epoxides (v) fatty amines other than component (b) above

(vi) glycerol esters, e.g., partial esters

(vii) borated glycerol esters

(viii) alkoxylated fatty amines (ix) borated alkoxylated fatty amines

(x) metal salts of fatty acids

(xi) sulfurized olefins

(xii) fatty imidazolines

(xiii) condensation products of carboxylic acids and polyalkylene- poly amines

(xiv) metal salts of alkyl salicylates

(xv) amine salts of alkylphosphoric acids

(xvi) ethoxylated alcohols and mixtures thereof. [0036] Representatives of each of these types of friction modifiers are known and are commercially available. For instance, (i) fatty phosphites are generally of the formula (RO)₂PHO. The dialkyl phosphite, as shown in the preceding formula, is typically present with a minor amount of monoalkyl phosphite of the formula (RO)(HO)PHO. In these structures, the term "R" is conventionally referred to as an alkyl group. It is, of course, possible that the alkyl is actually alkenyl and thus the terms "alkyl" and "alkylated," as used herein, will embrace other than saturated alkyl groups within the phosphite. The phosphite should have sufficient hydrocarbyl groups to render the phosphite substantially oleophilic. In one embodiment, the hydrocarbyl groups are substantially un- branched. Many suitable phosphites are available commercially and may be synthesized as described in U.S. Patent 4,752,416. The phosphite may contain 8 to 24 carbon atoms in each of R groups. In certain embodiments, the fatty phosphite contains 12 to 22 carbon atoms in each of the fatty radicals, alternatively 16 to 20 carbon atoms. In one embodiment the fatty phosphite can be formed from oleyl groups, thus having 18 carbon atoms in each fatty radical.

[0037] (iv) Borated fatty epoxides are known from Canadian Patent No. 1,188,704. These oil-soluble boron- containing compositions are prepared by reacting, at a temperature from 80⁰C to 250⁰C, boric acid or boron trioxide with at least one fatty epoxide having the formula O

/ \ R¹R²C-CR³R⁴ wherein each of R¹, R², R³ and R⁴ is hydrogen or an aliphatic radical, or any two thereof together with the epoxy carbon atom or atoms to which they are attached, form a cyclic radical. The fatty epoxide may, in one embodiment, contain at least 8 carbon atoms.

[0038] The borated fatty epoxides can be characterized by the method for their preparation which involves the reaction of two materials. Reagent A can be boron trioxide or any of the various forms of boric acid including metaboric acid (HBO₂), orthoboric acid (H3BO3) and tetraboric acid (H2B4O7). Boric acid, and especially orthoboric acid, may be used. Reagent B can be at least one fatty epoxide having the above formula. In the formula, each of the R groups is most often hydrogen or an aliphatic radical with at least one being a hydrocarbyl or aliphatic radical containing at least 6 carbon atoms. The molar ratio of reagent A to reagent B is generally 1 :0.25 to 1 :4. Ratios of 1 : 1 to 1 :3 may be used, with about 1 :2 being exemplary. The borated fatty epoxides can be prepared by merely blending the two reagents and heating them at temperature of 80° to 250⁰C, such as 100° to 200⁰C, for a period of time sufficient for reaction to take place. If desired, the reaction may be effected in the presence of a substantially inert, normally liquid organic diluent. During the reaction, water is evolved and may be removed by distillation.

[0039] (iii) Non-borated fatty epoxides, corresponding to "Reagent B" above, are also useful as friction modifiers. [0040] Borated amines are generally known from U.S. Patent 4,622,158. Borated amine friction modifiers (including (ix) borated alkoxylated fatty amines) are conveniently prepared by the reaction of a boron compounds, as described above, with the corresponding amines. The amine can be a simple fatty amine or hydroxy containing tertiary amines. The borated amines can be prepared by adding the boron reactant, as described above, to an amine reactant and heating the resulting mixture at a 50° to 300⁰C, such as 100⁰C to 25O⁰C or 15O⁰C to 23O⁰C, with stirring. The reaction is continued until by-product water ceases to evolve from the reaction mixture indicating completion of the reaction. [0041] Among the amines useful in preparing the borated amines are com- mercial alkoxylated fatty amines known by the trademark "ETHOMEEN" and available from Akzo Nobel. Representative examples of these ETHOMEEN™ materials is ETHOMEEN™ C/12 (bis[2-hydroxyethyl]-coco-amine); ETHOMEEN™ C/20 (polyoxyethylene[10]cocoamine); ETHOMEEN™ S/12 (bis[2-hydroxyethyl]soyamine); ETHOMEEN™ T/12 (bis[2-hydroxyethyl]- tallow-amine); ETHOMEEN™ T/15 (polyoxyethylene-[5]tallowamine); ETHOMEEN™ 0/12 (bis[2-hydroxyethyl]oleyl-amine); ETHOMEEN™ 18/12 (bis[2— hydroxyethyl]octadecylamine); and ETHOMEEN™ 18/25 (poly- oxyethyl-ene[15]octadecylamine). Fatty amines and ethoxylated fatty amines are also described in U.S. Patent 4,741,848.

[0042] The (viii) alkoxylated fatty amines, and (v) fatty amines themselves (such as oleylamine) are generally useful as friction modifiers in this invention. Such amines are commercially available.

[0043] Both borated and unborated fatty acid esters of glycerol can be used as friction modifiers. The (vii) borated fatty acid esters of glycerol are prepared by borating a fatty acid ester of glycerol with boric acid with removal of the water of reaction. In one embodiment, there is sufficient boron present such that each boron will react with from 1.5 to 2.5 hydroxyl groups present in the reaction mixture. The reaction may be carried out at a temperature in the range of 60⁰C to 135°C, in the absence or presence of any suitable organic solvent such as methanol, benzene, xylenes, toluene, or oil. [0044] (vi) Fatty acid esters of glycerol themselves can be prepared by a variety of methods well known in the art. Many of these esters, such as glycerol monooleate and glycerol tallowate, are manufactured on a commercial scale. The esters useful are oil-soluble and may be prepared from C8 to C22 fatty acids or mixtures thereof such as are found in natural products and as are described in greater detail below. Fatty acid monoesters of glycerol are suitable, although, mixtures of mono- and diesters may be used. For example, commercial glycerol monooleate may contain a mixture of 45% to 55% by weight monoester and 55% to 45% diester.

[0045] Fatty acids can be used in preparing the above glycerol esters; they can also be used in preparing their (x) metal salts, (ii) amides, and (xii) imida- zolines, any of which can also be used as friction modifiers. Suitable fatty acids include those containing 6 to 24 carbon atoms, or 8 to 18. The acids can be branched or straight-chain, saturated or unsaturated. Suitable acids include 2- ethylhexanoic, decanoic, oleic, stearic, isostearic, palmitic, myristic, palmitoleic, linoleic, lauric, and linolenic acids, and the acids from the natural products tallow, palm oil, olive oil, peanut oil, corn oil, and Neat's foot oil. A suitable acid is oleic acid. [0046] Suitable metal salts of acids include zinc and calcium salts. Zinc salt of carboxylic acids, for instance. These zinc salts may be acidic, neutral or basic (overbased). These salts may be prepared from the reaction of a zinc containing reagent with a carboxylic acid or salt thereof. A useful method of preparation of these salts is to react zinc oxide with a carboxylic acid. Useful carboxylic acids are those described hereinabove, and include those of the formula RCOOH, where R is an aliphatic or alicyclic hydrocarbon radical. Also suitable are those wherein R is a fatty group, e.g., stearyl, oleyl, linoleyl, or palmityl. Also suitable are zinc salts wherein zinc is present in a stoichiometric excess over the amount needed to prepare a neutral salt. Such salts include those wherein the zinc is present from about 1.1 to about 1.8 times the stoichiometric, especially from 1.3 to 1.6 times the stoichiometric amount of zinc. These zinc carboxylates are known in the art and are described in U.S. Pat. 3,367,869. Certain basic zinc salts can be represented by the general formula

Metal salts may also include calcium salts, such as overbased calcium salts.

[0047] Suitable amides are those prepared by condensation of an acid with ammonia or with primary or secondary amines such as diethylamine and dietha- nolamine. Fatty imidazolines are the cyclic condensation product of an acid with a diamine or polyamine such as a polyethylenepolyamine. The imidazolines are generally represented by the structure

where R is an alkyl group and R' is hydrogen or a hydrocarbyl group or a substituted hydrocarbyl group, including — (CH₂CH₂NH)n — groups. In one embodiment the friction modifier is the condensation product of a C8 to C24 fatty acid with a polyalkylene polyamine, and in particular, the product of isostearic acid with tetraethylenepentamine. The condensation products of carboxylic acids and polyalkyleneamines (xiii) may generally be imidazolines or amides. [0048] Sulfurized olefins (xi) are well known commercial materials used as friction modifiers. A suitable sulfurized olefin is one which is prepared in accordance with the detailed teachings of U.S. Patents 4,957,651 and 4,959,168. Described therein is a cosulfurized mixture of 2 or more reactants selected from the group consisting of (1) at least one fatty acid ester of a polyhydric alcohol, (2) at least one fatty acid, (3) at least one olefin, and (4) at least one fatty acid ester of a monohydric alcohol. [0049] Reactant (3), the olefin component, comprises at least one olefin. This olefin may be an aliphatic olefin, which usually will contain 4 to 40 carbon atoms, or 8 to 36 carbon atoms. Terminal olefins, or alpha-olefins, may be used, such as those having 12 to 20 carbon atoms. Mixtures of these olefins are commercially available, and such mixtures are contemplated for use in this invention.

[0050] The cosulfurized mixture of two or more of the reactants, is prepared by reacting the mixture of appropriate reactants with a source of sulfur. The mixture to be sulfurized can contain 10 to 90 parts of Reactant (1), or 0.1 15 parts by weight of Reactant (2); or 10 to 90 parts, often 15 to 60 parts, more often 25 to 35 parts by weight of Reactant (3), or 10 to 90 parts by weight of reactant (4). The mixture, in the present invention, includes Reactant (3) and at least one other member of the group of reactants identified as reactants (1), (2) and (4). The sulfurization reaction generally is effected at an elevated temperature with agitation and optionally in an inert atmosphere and in the presence of an inert solvent. The sulfurizing agents useful in the process of the present invention include elemental sulfur, hydrogen sulfide, sulfur halide plus sodium sulfide, and a mixture of hydrogen sulfide and sulfur or sulfur dioxide. Typically often 0.5 to 3 moles of sulfur are employed per mole of olefinic bonds. [0051] Metal salts of alkyl salicylates (xiv) include calcium and other salts of long chain (e.g. C12 to C16) alkyl-substituted salicylic acids.

[0052] Amine salts of alkylphosphoric acids (xv) include salts of oleyl and other long chain esters of phosphoric acid, with amines as described below. Useful amines in this regard are tertiary-aliphatic primary amines, sold under the tradename Primene™. The supplemental friction modifier can be used in addition to component (a). The amount of the supplemental friction modifier is generally 0.1 to 1.5 percent by weight of the lubricating composition, such as 0.2 to 1.0 or 0.25 to 0.75 percent. In some embodiments, however, the amount of the supplemental friction modifier is present at less than 0.2 percent or less than 0.1 percent by weight, for example, 0.01 to 0.1 percent. In one embodi- ment the amount of bis-(2-hydroxyethyl)tallowamine (commercially sold as Ethomeen-12™) in particular is restricted to these low amounts or less. [0053] Yet other suitable friction modifiers include friction modifiers derived from the reaction of a carboxylic acid or a reactive equivalent thereof with an aminoalcohol, wherein the friction modifier contains at least two hydrocarbyl groups, each containing at least 6 carbon atoms. Examples include the reaction product of isostearic acid or an alkyl succinic anhydride with tris- hydroxymethylaminomethane, which may be in a 2: 1 mole ratio. These friction modifiers are described in greater detail in US Application 2005-0250655. Also suitable are amide or thioamide friction modifiers represented by the formula

R¹R²N-C(X)R³ wherein X is O or S. R¹ and R² may be hydrocarbyl groups of at least 6 carbon atoms, and R³ is a hydroxyalkyl group of 1 to 6 carbon atoms or a group formed by the condensation of said hydroxyalkyl group, through a hydroxyl group thereof, with an acylating agent. An example of such a friction modifier is the condensation product of dicocoamine with glycolic acid. These friction modifi- ers are described in greater detail in International application serial No. PCT/US 2006/039768, filed October 11, 2006. In certain embodiments, no (or less than 0.1%) additional friction modifier is present, other than that of component (b). [0054] The compositions of the present invention can also include a detergent. Detergents as used herein are metal salts of organic acids. The organic acid portion of the detergent is a sulfonate, carboxylate, phenate, salicylate. The metal portion of the detergent is an alkali or alkaline earth metal. Suitable metals include are sodium, calcium, potassium and magnesium. Typically, the detergents are overbased, meaning that there is a stoichiometric excess of metal over that needed to form the neutral metal salt. [0055] Suitable overbased organic salts include the sulfonate salts having a substantially oleophilic character and which are formed from organic materials. Organic sulfonates are well known materials in the lubricant and detergent arts. The sulfonate compound should contain on average 10 to 40 carbon atoms, such as 12 to 36 carbon atoms or 14 to 32 carbon atoms on average. Similarly, the phenates, salicylates, and carboxylates have a substantially oleophilic character. [0056] While the present invention allows for the carbon atoms to be either aromatic or in paraffinic configuration, in certain embodiments alkylated aro- matics are employed. While naphthalene based materials may be employed, the aromatic of choice is the benzene moiety. [0057] A suitable composition is thus an overbased monosulfonated alkylated benzene, and may be the monoalkylated benzene. Typically, alkyl benzene fractions are obtained from still bottom sources and are mono- or di- alkylated. It is believed, in the present invention, that the mono-alkylated aromatics may be superior to the dialkylated aromatics in overall properties. [0058] It is desired that a mixture of mono-alkylated aromatics (benzene) be utilized to obtain the mono-alkylated salt (benzene sulfonate) in the present invention. The mixtures wherein a substantial portion of the composition contains polymers of propylene as the source of the alkyl groups assist in the solubility of the salt. The use of mono-functional (e.g., mono-sulfonated) materials avoids crosslinking of the molecules with less precipitation of the salt from the lubricant. [0059] In certain embodiments, the salt may be "overbased." By overbasing, it is meant that a stoichiometric excess of the metal be present over that required to neutralize the anion of the salt. The excess metal from overbasing has the effect of neutralizing acids which may build up in the lubricant. A second advantage is that the overbased salt increases the dynamic coefficient of fric- tion. Typically, the excess metal will be present over that which is required to neutralize the anion at in the ratio of up to 30: 1, such as 5 : 1 to 18: 1 on an equivalent basis.

[0060] The amount of the overbased salt utilized in the composition is typically 0.025 to 3 weight percent on an oil free basis, or 0.1 to 1.0 percent. The overbased salt is usually made up in about 50% oil with a TBN range of 10- 600 on an oil free basis. Borated and non-borated overbased detergents are described in U.S. Patents 5,403,501 and 4,792,410.

[0061] The compositions of the present invention can also include at least one phosphorus acid, phosphorus acid salt, phosphorus acid ester or derivative thereof including sulfur-containing analogs in the amount of 0.002-1.0 weight percent. The phosphorus acids, salts, esters or derivatives thereof include phosphoric acid, phosphorous acid, phosphorus acid esters or salts thereof, phosphites, phosphorus-containing amides, phosphorus-containing carboxylic acids or esters, phosphorus-containing ethers, and mixtures thereof. [0062] In one embodiment, the phosphorus acid, ester or derivative can be an organic or inorganic phosphorus acid, phosphorus acid ester, phosphorus acid salt, or derivative thereof. The phosphorus acids include the phosphoric, phos- phonic, phosphinic, and thiophosphoric acids including dithiophosphoric acid as well as the monothiophosphoric, thiophosphinic and thiophosphonic acids. One group of phosphorus compounds are alkylphosphoric acid mono alkyl primary amine salts as represented by the formula O R¹O - P - O ⁺NH₃R³ R²O where R¹, R², R³ are alkyl or hydrocarbyl groups or one of R¹ and R² can be H. The materials can be a 1 : 1 mixture of dialkyl and monoalkyl phosphoric acid esters. Compounds of this type are described in U.S. Patent 5,354,484. [0063] Eighty-five percent phosphoric acid is a suitable material for addition to the fully-formulated compositions and can be included at a level of 0.01-0.3 weight percent based on the weight of the composition, such as 0.03 to 0.2 or to 0.1 percent.

[0064] Other materials can optionally be included in the compositions of the present invention, provided that they are not incompatible with the afore- mentioned required components or specifications. Such materials include antioxidants (that is, oxidation inhibitors), including hindered phenolic antioxidants, secondary aromatic amine antioxidants such as dinonyldiphenylamine as well as such well-known variants as monononyldiphenylamine and diphenyl- amines with other alkyl substituents such as mono- or di-ocyl, sulfurized pheno- lie antioxidants, oil-soluble copper compounds, phosphorus-containing antioxidants, and organic sulfides, disulfides, and polysulfϊdes such as 2-hydroxy- alkyl, alkyl thioethers or 1 -t-dodecylthio-2-propanol or sulfurized 4- carbobutoxycyclohexene or other sulfurized olefins. Other optional components include seal swell compositions, such as isodecyl sulfolane or phthalate esters, which are designed to keep seals pliable. Also permissible are pour point depressants, such as alkylnaphthalenes, polymethacrylates, vinyl ace- tate/fumarate or /maleate copolymers, and styrene/maleate copolymers. Another material is an anti-wear agent such as zinc dialkyldithiophosphates. These optional materials are known to those skilled in the art, are generally commer- cially available, and are described in greater detail in published European Patent Application 761,805. Also included can be known materials such as corrosion inhibitors (e.g., tolyltriazole, dimercaptothiadiazoles), dyes, fluidizing agents, odor masking agents, and antifoam agents. Organic borate esters and organic borate salts can also be included. [0065] The above components can be in the form of a fully-formulated lubricant or in the form of a concentrate within a smaller amount of lubricating oil. If they are present in a concentrate, their concentrations will generally be directly proportional to their concentrations in the more dilute form in the final blend.

Examples

[0066] Lubricant formulations are prepared with the following components:

a. Dispersant treated with terephthalic acid (TPA), optionally also treated with dimercaptothiadiazole, inorganic phosphorus acid, and/or boron b. DMTD = dimercaptothiadiazole c. secondary amine(s) having 2-ethylhexyl and hydrogenated tallow alkyl groups d. May include small amounts of other materials commonly present such as a viscosity index improver or an anti-foam agent.

[0067] The friction modifier (a), used in combination with the dispersant (b) present in the base formulation, will provide good friction properties.

[0068] Each of the documents referred to above is incorporated herein by reference. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word "about." Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade. However, the amount of each chemical component is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, unless otherwise indicated. It is to 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. As used herein, the expression "consisting essentially of permits the inclusion of substances that do not materially affect the basic and novel characteristics of the composition under consideration.

Claims

What is claimed is:

1. A composition suitable for lubricating a transmission, comprising: (a) a major amount of an oil of lubricating viscosity; (b) a tertiary amine being represented by the formula

R¹R²NR³ wherein R¹ and R² are each independently an alkyl group of at least 6 carbon atoms and R³ is a polyhydroxyl-containing alkyl group or a polyhydroxyl- containing alkoxy alkyl group; and (c) a dispersant.

2. The composition of claim 1 wherein R¹ and R² are each independently alkyl groups of about 8 to about 20 carbon atoms.

3. The composition of claim 1 wherein the tertiary amine is a product derived from di-cocoalkyl amine.

4. The composition of claim 1 wherein R³ is a polyol-containing alkyl group.

5. The composition of claim 1 wherein the amine of (b) is represented by the formula

R¹R²N-CH₂-CHOH-CH₂OH wherein R¹ and R² are each independently alkyl groups of about 8 to about 20 carbon atoms.

6. The composition of claim 1 wherein the amine of (b) comprises the reaction product of di-cocoamine and one or more moles of 2,3-epoxy-l- propanol or 3-chloropropane-l,2-diol.

7. The composition of claim 1 wherein the amount of the amine of (b) is about 0.01 to about 10 percent by weight.

8. The composition of claim 1 wherein the dispersant comprises a succinimide dispersant.

9. The composition of claim 1 wherein the amount of the dispersant is about 0.3 to about 10 percent by weight.

10. The composition of claim 1 further comprising at least one additive selected from the group consisting of detergents, antioxidants, seal swell agents, anti-wear agents, and friction modifiers.

11. The composition of claim 1 further comprising at least one additive selected from the group consisting of organic borate esters organic borate salts, organic phosphorus esters, organic phosphorus salts, inorganic phosphorus acids, and inorganic phosphorus salts.

12. The composition prepared by mixing the components of claim 1.

13. A concentrate suitable for dilution with oil of lubricating viscosity to prepare a lubricant for a transmission, comprising:

(a) a concentrate-forming amount of an oil of lubricating viscosity;

(b) a tertiary amine being represented by the formula

(c) a dispersant.

14. A method for lubricating a transmission, comprising supplying thereto a lubricant comprising: (a) a major amount of an oil of lubricating viscosity; and

(b) a tertiary amine being represented by the formula

R¹R²NR³ wherein R¹ and R² are each independently an alkyl group of at least 6 carbon atoms and R³ is a polyhydroxyl-containing alkyl group or a polyhydroxyl- containing alkoxy alkyl group.

15. The method of claim 14 wherein the transmission is an automatic transmission.