POWER TRANSMITTING FLUIDS WITH IMPROVED SHIFT DURABILITY

Abstract: The shift durability of power transmitting fluids, such as manual transmission fluids, are improved by additive combinations incorporating amine phosphates and neutral or acidic friction modifiers.

Description: POWER TRANSMITTING FLUIDS WITH IMPROVED SHIFT DURABILITY BACKGROUND OF THE INVENTION This invention relates to a composition and a method of improving the shift durability of power transmitting fluids, particularly power transmitting fluids such as manual transmission fluids (MTF's), and more particularly to improved synchromesh durability of MTF's. A common goal of automobile manufacturers is to produce vehicles that are durable and perform reliably over their service life. In the case of MTF's, not only should the transmission not fail during the lifetime of the vehicle, but its shift characteristics should not perceptively change over this period. Since shift characteristics of manual transmissions are largely dependent on the frictional characteristics, the MTF needs to have very stable frictional performance with time, and therefore mileage. This aspect of MTF performance is known as friction durability. Currently many vehicle builders are moving to "fill-for-life" fluids which creates the need for shift durable MTF's since the fluid will no longer be drained and replaced at regular intervals. EP 237804 purports to solve the synchromesh gear shifting problems of "clashing" (identified as a high-speed gear shifting problem) and "sticking" (identified as a low-speed gear shifting problem) by providing a base oil containing an essential ingredients (based on weight): 0.2 to 5 parts of a sulfurized oil or sulfurized ester; 0.1 to 5 parts of a phosphorous ester; 0.2 to 5 parts of a zinc dithiophosphate; and 2 to 5 parts of a metallic detergent. However, this publication does not address the problem of improved shift durability. We have found that a combination of amine phosphates and neutral and/or acidic friction modifiers confer outstanding shift durability to MTF's. SUMMARY OF THE INVENTION This invention relates to power transmitting fluid compositions and a method for improving the shift durability of these fluids comprising: (1 ) a major amount of a lubricating oil; and (2) a shift-durability improving effective amount of an additive combination comprising: (a) an amine phosphate; and (b) a neutral or acidic friction modifier. DETAILED DESCRIPTION OF THE INVENTION This invention describes a composition and method for improving the shift durability of power transmitting fluids. While the benefits of this invention are exemplified in manual transmissions, they may be equally applicable to other types of power transmitting fluids such as automatic transmission fluids, gear oils, hydraulic fluids, heavy duty hydraulic fluids, industrial oil, power steering fluids, pump oils, tractor fluids, universal tractor fluids and the like. These power transmitting fluids can be formulated with a variety of performance additives and in a variety of base oils. Lubricating Oils Lubricating oils useful in this invention are derived from natural lubricating oils, synthetic lubricating oils, and mixtures thereof. In general, both the natural and synthetic lubricating oil will each have a kinematic viscosity ranging from about 1 to about 40 mm^/s (cSt) at 100°C, although typical applications will require each oil to have a viscosity ranging from about 2 to about 8 mm 2 /s (cSt) at 100°C. Natural lubricating oils include animal oils, vegetable oils (e.g., castor oil and lard oil), petroleum oils, mineral oils, and oils derived from coal or shale. The preferred natural lubricating oil is mineral oil. Suitable mineral oils include all common mineral oil base stocks. This includes oils that are naphthenic or paraffinic in chemical structure. Oils that are refined by conventional methodology using acid, alkali, and clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents such as phenol, sulphur dioxide, furfural, dichlordiethyl ether, etc. They may be hydrotreated or hydrofined, dewaxed by chilling or catalytic dewaxing processes, or hydrocracked. The mineral oil may be produced from natural crude sources or be composed of isomerized wax materials or residues of other refining processes. Typically the mineral oils will have kinematic viscosities of from 2.0 mm 2 /s (cSt) to 8.0 mm 2 /s (cSt) at 100°C. The preferred mineral oils have kinematic viscosities of from 2 to 6 mm 2 /s (cSt), and most preferred are those mineral oils with viscosities of 3 to 5 mm 2 /s (cSt) at 100°C. Synthetic lubricating oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as oligomerized, polymerized, and interpolymerized olefins [e.g., polybutylenes, polypropylenes, propylene, isobutylene copolymers, chlorinated polylactenes, poly(l-hexenes), poly(l-octenes), poly- (1-decenes), etc., and mixtures thereof]; alkylbenzenes [e.g., dodecyl- benzenes, tetradecylbenzenes, dinonyl-benzenes, di(2-ethylhexyl)benzene, etc.]; polyphenyls [e.g., biphenyls, terphenyls, alkylated polyphenyls, etc.]; and alkylated diphenyl ethers, alkylated diphenyl sulfides, as well as their derivatives, analogs, and homologs thereof, and the like. The preferred oils from this class of synthetic oils are oligomers of α-olefins, particularly oligomers of 1-decene. Synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers, and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc. This class of synthetic oils is exemplified by: polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide; the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methy l-polyisopropylene glycol ether having an average molecular weight of 1000, diphenyl ether of polypropylene glycol having a molecular weight of 1000 - 1500); and mono- and poly-carboxylic esters thereof (e.g., the acetic acid esters, mixed C3-C8 fatty acid esters, and C-12 oxo ac ' d diester of tetraethylene glycol). Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebasic acid, fumaric acid, adipic acid, linoieic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoethers, propylene glycol, etc.). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoieic acid dimer, and the complex ester formed by reacting one mole of sebasic acid with two moles of tetraethylene glycol and two moles of 2-ethyl- hexanoic acid, and the like. A preferred type of oil from this class of synthetic oils are adipates of C4 to C-12 alcohols. Esters useful as synthetic lubricating oils also include those made from C5 to C-12 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane pentaerythritol, dipentaerythritol, tripentaerythritol, and the like. Silicon-based oils (such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils) comprise another useful class of synthetic lubricating oils. These oils include tetra-ethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-2-ethylhexyl) silicate, tetra-(p-tert-butylphenyl) silicate, hexa-(4-methyl-2-pentoxy)-disiloxane, poly(methyl)-siloxanes and poly(methylphenyl) siloxanes, and the like. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, and diethyl ester of decylphosphonic acid), polymeric tetra-hydrofurans, poly-α-olefins, and the like. The lubricating oils may be derived from refined, rerefined oils, or mixtures thereof. Unrefined oils are obtained directly from a natural source or synthetic source (e.g., coal, shale, or tar sands bitumen) without further purification or treatment. Examples of unrefined oils include a shale oil obtained directly from a retorting operation, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process, each of which is then used without further treatment. Refined oils are similar to the unrefined oils except that refined oils have been treated in one or more purification steps to improve one or more properties. Suitable purification techniques include distillation, hydrotreating, dewaxing, solvent extraction, acid or base extraction, filtration, and percolation, all of which are known to those skilled in the art. Rerefined oils are obtained by treating used oils in processes similar to those used to obtain the refined oils. These rerefined oils are also known as reclaimed or reprocessed oils and are often additionally processed by techniques for removal of spent additives and oil breakdown products. When the lubricating oil is a mixture of natural and synthetic lubricating oils (i.e., partially synthetic), the oil typically will contain 1 to 80, preferably from about 10 to 75, most preferably from about 10 to 50 weight percent synthetic lubricating oil. While the choice of the partial synthetic oil components may widely vary, particularly useful combinations are comprised of mineral oils and poly-α-olefins (PAO), particularly oligomers of 1-decene. Amine Phosphates The amine phosphates useful in this invention are the neutralisation or partial neutralisation products of acidic phosphorus-containing intermediates and amines. The acidic intermediates are preferably formed from a hydroxy- substituted triester of a phosphorothioic acid with an inorganic phosphorus reagent selected from the group consisting of phosphorus acids, phosphorus oxides, and phosphorus halides. The hydroxy-substituted triesters of phosphorothioic acids include principally those having the structural formula R-0 X R-O/ ^X-R wherein R is selected from the class consisting of substantially hydrocarbon radicals and hydroxy-substituted substantially hydrocarbon radicals, at least one of the R radicals being a hydroxy-substituted substantially hydrocarbon radical, and X is selected from the class consisting of sulphur and oxygen, at least one of the X radicals being sulphur. The substantially hydrocarbon radicals include aromatic, aliphatic, and cycloaliphatic radicals such as aryl, alkyl, aralkyl, alkaryl, and cycloalkyl radicals. Such radicals may contain a polar substituent such as chloro, bromo, iodo, alkoxy, aryloxy, nitro, keto, or aldehydo group. In most instances there should be no more than one such polar group in a radical. Specific examples of the substantially hydrocarbon radical are methyl, ethyl, isopropyl, secondary-butyl, isobutyl, n-pentyl, dodecyl, polyisobutene radical (molecular weight of 1500), cyclohexyl, cyclopentyl, 2-heptyl- cyclohexyl, phenyl, naphthyl, xenyl, p-heptylphenyl, 2,6-di-tertiary- butylphenyl, benzyl, phenylethyl, 3,5-dodecylphenyl, chlorophenyl, alpha- methoxy-beta-naphthyl, p-nitrophenyl, p-phenoxyphenyl, 2-bromomethyl, 3- chlorocyclohexyl, and polypropylene (molecular weight of 300)-substituted phenyl radical. The hydroxy-substituted substantially hydrocarbon radicals include principally the above-illustrated substantially hydrocarbon radicals containing a hydroxy group. Those having less than about 8 carbon atoms are preferred because of the convenience in preparing such hydroxy-substituted triesters. Examples of such radicals are hydroxymethyl, hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxycyclohexyl, 2-hydroxycyclopentyl, 2-hydroxy-1- octyl, l-hydroxy-3-octyl, 1-hydroxy-2-octyl, 2-hydroxy-3-phenyl-cyclohexyl, 1- hydroxy-2-phenylethyl, 2-hydroxy-1 -phenylethyl, 2-hydroxy-1-p-tolylethyl, and 2-hydroxy-3-butyl radicals. Other hydroxy-substituted substantially hydrocarbon radicals are exemplified by 2,5-dihydroxyphenyl, alpha-hydroxy- beta-naphthyl, 3-hydroxy-4-dodecyl, 3-hydroxy-6-octadecyl, and p-(p- hydroxyphenyl)-phenyl radicals. A preferred class of the hydroxy-substituted triesters comprises those having the structural formula where R" is a substantially hydrocarbon radical illustrated above and R' is a bivalent substantially hydrocarbon radical such as alkylene or arylene radicals derived from the previously illustrated substantially hydrocarbon radicals. A convenient method for preparing such esters involves the reaction of a phosphorodithioic acid with an epoxide or a glycol. Such reaction is known in the art. The following equations are illustrative of the reaction. where u is an epoxide and HO - R' - OH is a glycol. For reasons of economy, aliphatic epoxides having less than about 8 carbon atoms and styrene oxides are preferred for use in the above process. Especially useful epoxides are exemplified by ethylene oxide, propylene oxide, styrene oxide, alpha-methylstyrene oxide, p-methylstyrene oxide, cyclohexene oxide, cyclopentene oxide, dodecene oxide, octadecene oxide, 2,3-butene oxide, 1 ,2-butene oxide, 1 ,2-octene oxide, 3,4-pentene oxide, and 4-phenyl-1 ,2-cyclohexene oxide. Glycols include both aliphatic and aromatic di-hydroxy compounds. The latter are exemplified by hydroquinone, catechol, resorcinol, and 1 ,2-dihydroxynaphthalene. Aliphatic glycols are especially useful such as ethylene glycol, trimethylene glycol, tetramethylene glycol, decamethylene glycol, di-ethylene glycol, triethylene glycol, and pentaethylene glycol. Another convenient method for preparing the hydroxy-substituted triesters comprises the addition of a phosphorodithioic acid to an unsaturated alcohol such as allyl alcohol, cinnamyl alcohol, or oleyl alcohol such as is described in U.S. Patent 2,528,723. Still another method involves the reaction of a metal phosphorothiate with a halogen-substituted alcohol described in U.S. Reissue Patent 20,411. The phosphorodithioic acids from which the hydroxy-substituted triesters can be derived are likewise well-known. They are prepared by the reaction of phosphorus pentasulfide with an alcohol or a phenol. The reaction involves 4 moles of the alcohol or phenol per mole of phosphorus pentasulfide and may be carried out within the temperature range from about 50°C to about 200°C. Thus, the preparation of O.O'-di-n- hexylphosphorodithioic acid involves the reaction of phosphorus pentasulfide with 4 moles of n-hexyl alcohol at about 100°C for about 2 hours. Hydrogen sulfide is liberated and the residue is the defined acid. The preparation of the phosphoromonothioic acid may be effected by treatment of corresponding phosphorodithioic acid with steam. Phosphorotrithioic acids and phosphorotetrathioic acids can be obtained by the reaction of phosphorus pentasulfide with mercaptans or mixtures of mercaptans and alcohols. The reaction of phosphorus pentasulfide with a mixture of phenols or alcohols (e.g., isobutanol and n-hexanol in 2:1 weight ratio) results in phosphorodithioic acids in which the two organic radicals are different. Such acids likewise are useful herein. The inorganic phosphorus reagent useful in the reaction with the hydroxy-substituted triesters of phosphorothioic acids is preferably phosphorus pentoxide. Other phosphorus oxides such as phosphorus trioxide and phosphorus tetroxide likewise are useful. Also useful are phosphorus acids, and phosphorus halides. They are exemplified by phosphoric acid, pyrophosphoric acid, metaphosphoric acid, hypophosphoric acid, phosphorous acid, pyrophosphorous acid, metaphosphorous acid, hypophosphorous acid, phosphorous trichloride, phosphorus tribromide, phosphorous pentachloride, monobromophosphorus tetrachloride, phosphorus oxychloride, and phosphorus triiodide. The reaction of the hydroxy-substituted triesters of phosphorothioic acids with the inorganic phosphorus reagent results in an acidic product. The chemical constitution of the acidic product depends to a large measure on the nature of the inorganic phosphorus reagent used. In most instances the product is a complex mixture the precise composition of which is not known. It is known, however, that the reaction involves the hydroxy radical of the triester with the inorganic phosphorus reagent. In this respect the reaction may be likened to that of an alcohol or a phenol with the inorganic phosphorus reagent. Thus, the reaction of the hydroxy-substituted triester with phosphorus pentoxide is believed to result principally in acidic phosphates, i.e., mono- or di-esters of phosphoric acid in which the ester radical is the residue obtained by the removal of the hydroxy radical of the phosphorothioic triester reactant. The product may also contain phosphonic acids and phosphinic acids in which one or two direct carbon-to-phosphorus linkages are present. The acidic product of the reaction between the hydroxy-substituted triester with phosphorus oxyhalide or phosphoric acid is believed to result in similar mixtures of acidic phosphates, phosphonic acids, and/or phosphinic acids. On the other hand, the reaction of the hydroxy-substituted triester with phosphorus trichloride or phosphorus acid is believed to result principally in acidic organic phosphites. Still other products may be obtained from the use of other inorganic phosphorus reagents illustrated previously. In any event, the product is acidic and as such is useful as the intermediate for the preparation of the neutralized products useful in invention. Usually, from about 2 moles to about 5 moles of the triester is used for each mole of the inorganic phosphorus reagent. The preferred proportion of the triester is about 3-4 moles for each mole of the phosphorus reagent. The use of amounts of either reactant outside the limits indicated here results in excessive unused amounts of the reactant and is ordinarily not preferred. The reaction of the hydroxy-substituted triester with the inorganic phosphorus reagent to produce the acidic intermediate can be effected simply by mixing the two reactant at a temperature above about room temperature, preferably above about 50°C. A higher temperature such as 100°C or 150°C may be used but ordinarily is unnecessary. The amines useful for neutralizing the acidic intermediate may be aliphatic amines, aromatic amines, cycloaliphatic amines, heterocyclic amines, or carbocyclic amines. Amines having from about 4 to about 30 aliphatic carbon atoms ore preferred and aliphatic primary amines containing at least about 8 carbon atoms and having the formula, R" - NH2, where R" is, for example, an aliphatic radical such as tert-octyl, tert-dodecyl, tert- tetradecyl, tert-octadecyl, cetyl, behenyl, stearyl, eicosyl, docosyl, tetracosyl, hexatriacontanyl, and pentahexacontanyl, are especially useful. Examples of other aliphatic amines include cyclohexyl amine, n-hexylamine, dodecylamine, di-dodecylamine, tridodecylamine, N-methyl-octylamine, butylamine, behenylamine, stearyl amine, oleyl amine, myristyl amine, and N- dodecyl trimethylene diamine, aniline, o-toluidine, benzidine, phenylene diamine, N,N'-di-sec-butylphenylene diamine, beta-naphthylamine, alpha- naphthylamine, morpholine, piperazine, menthane diamine, cyclopentyl amine, ethylene diamine, hexamethylene tetramine, octamethylene diamine, and N,N'-dibutyl-phenylene diamine. Also useful are hydroxy-substituted amines such as ethanolamine, diethanolamine, triethanolamine, isopropanolamine, para-aminophenol, 4-amino-naphthol-1 , 8-amino-naphthol- 1 , beta-aminoalizarin, 2-amino-2-ethyl-1 ,3-propandiol, 4-amino-4'-hydroxy- diphenyl ether, 2-amino-resorcinol, etc. Of the various available hydroxy-substituted amines which can be employed, a preference is expressed for hydroxy-substituted aliphatic amines, particularly those which conform for the most part to the formula κ Q R" - N X (AO) x H wherein R" is as previously defined; A is a lower alkylene radical such as methylene, ethylene, propylene-1 ,2, tri-methylene, butylene-1 ,2, tetramethylene, amylene-1 ,3, pentamethylene, etc.; x is 1-10, inclusive; and Q is hydrogen, (AO) x H, or R". The use of such hydroxy-substituted aliphatic amines in many instances imparts improved rust-inhibiting characteristics to the phosphorus and nitrogen-containing compositions of this invention. Examples of such preferred hydroxy-substituted aliphatic amines include N-4- hydroxybutyl-dodecyl amine, N-2-hydroxyethyl-n-octylamine, N-2- hydroxypropyl dinonylamine, N,N-di-(3-hydroxypropyl)-tert-dodecyl amine, N- hydroxytrieth-oxyethyl-tert-tetradecyl amine, N-2-hydroxyethyl-tert-dodecyl amine, N-hydroxyhexa-propoxypropyl-tert-octadecyl amine, N-5- hydroxypentyl di-n-decyl amine, etc. A convenient and economical method for the preparation of such hydroxy-substituted aliphatic amines involves the known reaction of an aliphatic primary or secondary amine with at least about an equimolecular amount of an epoxide, preferably in the presence of a suitable catalyst such as sodium methoxide, sodamide, sodium metal, etc. R"NH2 + χAO *- R"N κ H (AO) x H R"2NH + x AO * - R"2N(AO) x H In the above formulae, R", x and A are as previously defined. A particular preference is expressed for N-monohydroxyalkyl substituted mono-tertiary- alkyl amines of the formula tert-R - NHAOH, wherein tert-R is a tertiary-alkyl radical containing from about 11 to about 24 carbon atoms. In lieu of a single compound of the formula tert-R - NHAOH, it is often convenient and desirable to use a mixture of such compounds prepared, for example, by the reaction of an epoxide such as ethylene oxide, propylene oxide, or butylene oxide with a commercial mixture of tertiary-alkyl primary amines such as C-j -|-C-|4 tertiary- alkyl primary amines, C-J3-C22 tertiary-alkyl primary amines, etc. The neutralization of the acidic intermediate with the amine is in most instances exothermic and can be carried out simply by mixing the reactants at ordinary temperatures, preferably from about 0°C to about 200°C. The chemical constitution of the neutralized product of the reaction depends to a large extent upon the temperature. Thus, at a relatively low temperature, such as less than about 80°C, the product comprises predominantly a salt of the amine with the acid. At a temperature above 100°C, the product may contain amides, amidines, or mixtures thereof. However, the reaction of the acidic intermediate with a tertiary amine results only in a salt. The relative proportions of the acidic intermediate and the amines used in the reaction are preferably such that a substantial portion of the acidic intermediate is neutralized. The lower limit as to the amount of amine used in the reaction is based primarily upon a considerable of the utility of the product formed. In most instances, enough amine should be sued as to neutralize at least about 50% of the acidity of the intermediate. For use as additives in hydrocarbon oils, substantially neutral products such as are obtained by neutralization of at least about 90% of the acidity of the intermediate are desirable. Thus the amount of the amine used may vary within wide ranges depending upon the acidity desired in the product and also upon the acidity of the intermediate as determined by, for example, ASTM procedure designation D-664 or D-974. A particularly preferred amine phosphate is when the acidic intermediate is derived from the reaction of P2O5 with hydroxypropyl O,O- di(4-methyl-2-pentyl) phosphorodithioate. This acidic intermediate may then be neutralised or partially neutralised with a C-|2 to C14 tertiary aliphatic primary amine. An example of such an amine may be commercially purchased under the trade name of Primene 81 R. While any effective amount of the amine phosphate may be used in the compositions of this invention, typically the amine phosphate will be present in a finished MTF in an amount from 0.01 to 5, preferably from 0.05 to 4, most preferably from 0.1 to 3 weight percent. Neutral or Acidic Friction Modifiers The friction modifiers useful in this invention are those which are neutral or acidic in nature Friction modifiers which are substantially neutral, i.e., mildly basic, are also contemplated as within the scope of this invention. However, friction modifiers that are basic in nature (e g oleamide, stearamide, etc ) do not form part of this invention. Examples of neutral friction modifiers include alcoholic esters and salts of mono- and polycarboxylic acids and their anhydrides Acidic friction modifiers include mono- and polycarboxylic acids and their anhydrides and partial alcoholic esters Examples of suitable monocarboxylic acids are fatty acids having from 9 to 30 carbon atoms in the aliphatic chain Examples of fatty acids include nonanoic (pelargonic), decanoic (capπc), undecanoic, dodecanoic (launc), tπdecanoic, tetradecanoic (myristic), pentadecanoic, hexadecanoic (palmytic), heptadecanoic (margaπc), octadecanoic (stearic or iso-steaπc), nonadecanoic, eιcosιc(arachidιc), decenoic, undecenoic, dodecenoic; tπdecenoic, pentadecenoic, hexadecenoic, heptadecenoic, octadecenoic (oleic), eicosenoic or mixtures thereof Examples of suitable polycarboxylic acid and their anhydrides are dimer derivatives of the foregoing fatty acids, (e.g , oleic acid dimer) and hydrocarbyl substituted succinic anhydrides, where the hydrocarbyl substituent is is a C- * 2 to C30 aliphatic hydrocarbyl group Particularly useful alcohols with the present invention are the diols represented by the structure HO - R-i - OH where R- * is a C- * to C- * 2 a, ky' radical, a C-| to C- * 2 alkylene radical, or Cβ to C20 ar yl radical. R- * may be straight or branched, it may contain hetero atoms (N, S, or O) and it also may contain aromatic substituents. Preferred diols of the present invention are: 1 ,4-butanediol, 1 ,5-hexanediol, thiodiglycol, dithiodiglycol, diethanolamine, and 1 ,2-propanediol. Also suitable for use with this invention are the triol alcohols and their derivatives. A preferred triol is glycerol. The friction modifiers of this invention are normally prepared by heating an acid or anhydride with an alcohol to form an ester or partial ester and removing the resulting water. However, other methods of preparation are known and can be used. Examples of friction modifier esters of diols are C- * 2 to C30 aliphatic hydrocarbyl substituted succinic acids or anhydrides reacted with diols and their metal salts as described in US Patent 4,702,850. Most preferred is the product of octadecenyl succinic anhydride and thiodiglycol. Examples of suitable friction modifier esters formed from triols are shown as structures (I), (II), and (III) where (I), (II), and (III) are represented by: O II HOCH2 - CH - CH 2 - O - C -R2 (II); and O - C - R 2 II O where: R2 is aliphatic hydrocarbyl, including straight chain, saturated or unsaturated hydrocarbyl group, typically aliphatic having from about 9 to about 29 , preferably from about 11 to about 23 and most preferably from about 15 to about 20 carbon atoms. The term 'hydrocarbyl' is used herein to include substantially hydrocarbyl groups, as well as purely hydrocarbyl groups. The description of these groups as being substantially hydrocarbyl means that they contain no non-hydrocarbyl substituents or non-carbon atoms which significantly . affect the hydrocarbyl properties relative to the description herein. Examples of tri-esters useful in this invention are: glycerol mono¬ oleate, glycerol dioleate, glycerol mono-isostearate, tri-glycerol di- isostearate, sorbitan mono-oleate, sorbitan sesquioleate, sorbitan trioleate, sorbitan stearate, sorbitan palmitate. The preferred friction modifiers of this type for use in this invention are glycerol mono-oleate and glycerol dioleate, and mixtures thereof. Also suitable are their metal salts, especially salts of copper. Treat rates of the friction modifiers of the present invention are from about 0.01 to about 5, preferably from 0.05 to 3, and most preferably from 0.05 to 1.5 weight percent in the finished MTF. Other additives known in the art may be added to the lubricating oil. These additives include corrosion inhibitors, antioxidants, dispersants, antiwear agents, metallic detergents, extreme pressure additives, seal swellants and the like. They are typically disclosed in, for example, "Lubricant Additives" by C. V. Smalheer and R. Kennedy Smith, 1967, pp. 1- 11 and U.S. Patent 4,105,571. Representative amounts of these additives in a fully formulated MTF are summarized as follows: Additive (Broad) Wt.% (Preferred) Wt.% VI Improvers 1 - 12 1 - 8 Corrosion Inhibitor 0.01 - 3 0.02 - 1 Antioxidants 0.1 - 5 0.25 - 3 Dispersants 0.10 - 10 2 - 8 Antifoaming Agents 0.0 - 1 0.001 - 0.5 Metallic Detergents 0.0 - 6 0.01 - 3 Antiwear Agents 0.0 - 5 0.2 - 3 Pour Point Depressants 0.0 - 2 0.0 - 1.5 Seal Swellants 0.1 - 8 0.5 - 5 Lubricating Oil Balance Balance Suitable viscosity index improvers include homopolymers and copolymers of two or more monomers of C2 to C30 olefins. Suitable olefins include both alpha-olefins and internal olefins, which may be straight or branched, aliphatic aromatic, alkyl-aromatic, cyclo-alphatic, etc. Frequently they will be of ethylene with C3 to C30 olefins, particularly preferred being the copolymers of ethylene and propylene. Other polymers can be used such as polyisobutylenes, homopolymers and copolymers of C β and higher alpha- olefins, atactic polypropylene, hydrogenated polymers and copolymers and terpolymers of styrene, e.g., with isoprene and/or butadiene. Other suitable viscosity index improvers include polyacrylates and polymethyacrylates and their derivatives. Especially preferred are the polymethacrylates. Suitable corrosion inhibitors include mercapto- and hydrocarbylthio- disubstituted derivatives of 1 ,3,4-thiadiazole, e.g., C2 to C30; alkyl, aryl, cycloalkyl, aralkyl and alkaryl-mono-, di-, tri, or tetra- or thio-disubstituted derivatives thereof. Examples of such materials include 2,5-bis(octylthio) 1 ,3,4-thiadiazole; 2,5-bis(octyldithio)-1 ,3,4-thiadiazole; 2,5-bis(octyltrithio)- 1 ,3,4-thiadiazole; 2,5-bis(octyltetrathio)-1 ,3,4, -thiadiazole; 2,5-bis(nonylthio)- 1 ,3,4-thiadiazole; 2,5-bis(dodecyldithio)-1 ,3,4-thiadiazole; 2-dodecyldithio-5- phenyldithio-1 ,3,4-thiadiazole; 2-5-bis(cyclohexyldithio)-1 ,3,4-thiadiazole; and mixtures thereof. Preferred corrosion inhibitors are derivatives of 1 ,3,4-thiadiazoles such as those described in U.S Patent Nos. 2,719,125, 2,719,126 and 3,087,932. Especially preferred are the compounds 2,5-bis(t-octyldithio)- 1 ,3,4-thiadiazole commercially available as Amoco 150, 2,5-bis(t- nonyldithio)-1 ,3,4-thiadiazole, commercially available as Amoco 158, 2- nonyldisulfide-5-mercapto-1 ,3,4-thiadiazole, and their mixtures. Suitable seal swellants include mineral oils of the type that provoke swelling, including aliphatic alcohols of 8 to 13 carbon atoms such as tridecyl alcohol. A preferred seal swellant is an oil-soluble, saturated, aliphatic or aromatic hydrocarbon ester of from 10 to 60 carbon atoms and 2 to 4 linkages, e.g., dihexyl phthalate, as are described in U.S. Patent No. 3,974,081. Useful antioxidants are the ashless antioxidants such as arylamines and phenols, and the metal-containing antioxidants such as zinc dialkyldithiophosphates. The ashless antioxidants useful with this invention are either aryl amines or phenols. The amine type antioxidants include phenyl-alpha- naphthylamine, diphenylamine, phenothiazine, p-phenylene diamine, alkylated diphenylamines (e.g., p,p'-bis(alkylphenyl) amines wherein the alkyl groups contain from 8 to 12 carbons atoms each; such a material is Naugalube® 438L). Phenolic antioxidants include sterically hindered phenols (e.g., 2,6-di-t-butyl phenol, 4-methyl-2,6-di-t-butyl-phenol) and bis- phenols (4,4'-methylenebis(2,6-di-t-butylphenol); such a material is Ethyl® 702). Another class of phenolic antioxidants are the 4-substituted 2,6-di-t- butyl phenols, these would include materials such as 3,5-di-t-butyl-4- hydroxyhydrocinnamic acid, C7-C9 ester. (Such a material is Irganox® L- 135). The metal-containing zinc dithiodiphosphates antioxidants are produced by reaction of alcohols with P2S5 to produce diaikylthiophosphoric acids, which are then neutralized with zinc oxide. The preparation of zinc dithiodiphosphate is well known and discussed in much published literature. See for example the books, "Lubricant Additives," by CV. Smalheer and R K. Smith, published by Lezius-Hiles Co., Cleveland, Ohio (1967) and "Lubricant Additives," by M. W. Ranney, published by Noyes Data Corp., Park Ridge, N. J. (1973). Examples of such materials are zinc (di- isooctyldithiophosphoric acid) and zinc (di-2-ethylhexyldithiophosphoric acid) Other suitable antioxidants include P2S5 treated terpenes and their derivatives. Examples of suitable terpenes include isomeric terpene hydrocarbons having the formula C- * rjHβ such as contained in turpentine, pine oil and dipentenes, and the various synthetic and naturally occurring oxygen-containing derivatives. A particularly preferred terpene compound is α-pinene. Thus a preferred antioxidant in the P2S5 treated α-pinene reacted with a polyisobutenyl succinimide dispersant. Foam suppression can be provided by polysiloxane type compounds, e.g., silicone oil and polydimethyl siloxane. Suitable dispersants include hydrocarbyl succinimides, hydrocarbyl succinamides, mixed ester/amides of hydrocarbyl-substituted succinic acid, hydroxyesters of hydrocarbyl-substituted succinic acid, and Mannich condensation products of hydrocarbyl-substituted phenols, formaldehyde and polyamines. Mixtures of such dispersants can also be used. The preferred dispersants are the alkenyl succinimides. These include acyclic hydrocarbyl substituted succinimides formed with various amines or amine derivatives such as are widely disclosed in the patent literature. Use of alkenyl succinimides which have been treated with an inorganic acid of phosphorus (or an anhydride thereof) and a boronating agent are also suitable for use in the compositions of this invention as they are much more compatible with elastomeric seals made from such substances as fluoro-elastomers and silicon-containing elastomers. Polyisobutenyl succinimides formed from polyisobutenyl succinic anhydride and an alkylene polyamine such as triethylene tetramine or tetraethylene pentamine wherein the polyisobutenyl substituent is derived from polyisobutene having a number average molecular weight in the range of 500 to 5000 (preferably 800 to 2500) are particularly suitable. Dispersants may be post-treated with many reagents known to those skilled in the art. (see, e.g., U.S. Pat. Nos. 3,254,025, 3,502,677 and 4,857,214). Suitable metal-containing detergents are exemplified by oil-soluble neutral or overbased salts of alkali or alkaline earth metals with one or more of the following acidic substances (or mixtures thereof): (1 ) sulfonic acids, (2) carboxylic acids, (3) salicylic acids, (4) alkyl phenols, (5) sulfurized alkyl phenols, (6) organic phosphorus acids characterized by at least one direct carbon-to-phosphorus linkage. Such organic phosphorus acids include those prepared by the treatment of an olefin polymer (e g , polyisobutylene having a molecular weight of 1 ,000) with a phosphonzing agent such as phosphorus trichloride, phosphorus heptasulfide, phosphorus pentasulfide, phosphorus trichloride and sulfur, white phosphorus and a sulfur halide, or phosphorothioic chloride The preferred salts of such acids from the cost- effectiveness, toxicological, and environmental standpoints are the salts of sodium, potassium, lithium, calcium and magnesium The preferred salts useful with this invention are either neutral or overbased salts of calcium or magnesium Oil-soluble neutral metal-containing detergents are those detergents that contain stoichiometncally equivalent amounts of metal in relation to the amount of acidic moieties present in the detergent Thus, in general the neutral detergents will have a low basicity when compared to their overbased counterparts The acidic materials utilized in forming such detergents include carboxylic acids, salicylic acids, alkylphenols, sulfonic acids, sulfurized alkylphenols and the like The term "overbased" in connection with metallic detergents is used to designate metal salts wherein the metal is present in stoichiometncally larger amounts than the organic radical The commonly employed methods for preparing the over-based salts involve heating a mineral oil solution of an acid with a stoichiometric excess of a metal neutralizing agent such as the metal oxide, hydroxide, carbonate, bicarbonate, of sulfide at a temperature of about 50°C, and filtering the resultant product Examples of suitable metal-containing detergents include, but are not limited to, neutral and overbased salts of such substances as lithium phenates, sodium phenates, potassium phenates, calcium phenates, magnesium phenates, sulfurized lithium phenates, sulfurized sodium phenates, sulfurized potassium phenates, sulfurized calcium phenates, and sulfurized magnesium phenates wherein each aromatic group has one or more aliphatic groups to impart hydrocarbon solubility, lithium sulfonates, sodium sulfonates, potassium sulfonates, calcium sulfonates, and magnesium sulfonates wherein each sulfonic acid moiety is attached to an aromatic nucleus which in turn usually contains one or more aliphatic substituents to impart hydrocarbon solubility, lithium salicylates, sodium salicylates potassium salicylates, calcium salicylates and magnesium salicylates wherein the aromatic moiety is usually substituted by one or more aliphatic substituents to impart hydrocarbon solubility; the lithium, sodium, potassium, calcium and magnesium salts of hydrolyzed phosphosulfurized olefins having 10 to 2,000 carbon atoms or of hydrolyzed phosphosulfurized alcohols and/or aliphatic-substituted phenolic compounds having 10 to 2,000 carbon atoms; lithium, sodium, potassium, calcium and magnesium salts of aliphatic carboxylic acids and aliphatic substituted cycloaliphatic carboxylic acids; and many other similar alkali and alkaline earth metal salts of oil- soluble organic acids. Mixtures of neutral or over-based salts of two or more different alkali and/or alkaline earth metals can be used. Likewise, neutral and/or overbased salts of mixtures of two or more different acids (e.g. one or more overbased calcium phenates with one or more overbased calcium sulfonates) can also be used. As is well known, overbased metal detergents are generally regarded as containing overbasing quantities of inorganic bases, probably in the form of micro dispersions or colloidal suspensions. Thus the term "oil soluble" as applied to metallic detergents is intended to include metal detergents wherein inorganic bases are present that are not necessarily completely or truly oil- soluble in the strict sense of the term, inasmuch as such detergents when mixed into base oils behave much the same way as if they were fully and totally dissolved in the oil. Collectively, the various metallic detergents referred to herein above, have sometimes been called, simply, neutral, basic or overbased alkali metal or alkaline earth metal-containing organic acid salts. Methods for the production of oil-soluble neutral and overbased metallic detergents and alkaline earth metal-containing detergents are well known to those skilled in the art, and extensively reported in the patent literature. See for example, the disclosures of U.S. Pat. Nos. 2,001 ,108 2,081 ,075 2,095,538 2,144,078 2, 163,622 2,270, 183 2,292,205 2,335,017 2,399,877 2,416,281 2,451 ,345 2,451 ,346 2,485,861 2,501 ,731 2,501 ,732 2,585,520 2,671 ,758 2,616,904 2,616,905 2,616,906 2,616,911 2,616,924 2,616,925 2,617,049 2,695,910 3,178,368 3,367,867 3,496,105 3,629.109 3,865,737 3,907,691 4,100,085 4,129,589 4,137,184 4,184,740 4,212,752 4,617,135 4,647,387 4,880,550. The metallic detergents utilized in this invention can, if desired, be oil- soluble boronated neutral and/or overbased alkali of alkaline earth metal- containing detergents. Methods for preparing boronated metallic detergents are described in, for example, U.S. Pat. Nos. 3,480,548; 3,679,584; 3,829,381 ; 3,909,691 ; 4,965,003; 4,965,004. Preferred metallic detergents for use with this invention are neutral and overbased calcium or magnesium sulphurized phenates and neutral and overbased calcium or magnesium sulphonates. The additive combinations of this invention may be combined with other desired lubricating oil additives to form a concentrate. Typically the active ingredient (a.i.) level of the concentrate will range from 30 to 100, preferably from 40 to 95, most preferably from 50 to 90 weight percent of the concentrate. The balance of the concentrate is a diluent typically comprised of a lubricating oil or solvent. The shift durability characteristics of this invention are tested on a Hurth synchromesh rig. Briefly, the Hurth test rig consists of two (2) speed change gears and two (2) synchromesh rings. The rings function to equalise the speeds of the input and output gears prior to engagement (i.e., to accomplish a gear shift) and may be made of brass or bronze (less durable) or chemically-treated sintered materials (more durable). An electric motor provides the drive, and two flywheels are used to provide inertia. During a test cycle, one of the synchromesh rings slows one of the flywheels to a stop, before any gear engagement, and then the other synchromesh rings speeds up the same flywheel to allow engagement of the other gear. This test cycle is repeated until the synchromesh rings wear sufficiently to prevent smooth and rapid gear changing, which constitutes the end of the test. The additive combination of this invention was tested in the Hurth rig containing brass synchromesh rings and was reported as achieving over 100,000 cycles. A fluid achieving over 100,000 Hurth cycles is indicative of an extremely shift-durable fluid as present commercially known fluids typically fail the Hurth test between 2000 and 15,000 cycles using brass or bronze synchromesh rings. Even when using the more durable sintered synchromesh rings, the commercially available products were only capable of achieving Hurth failures in the range of 40,000 to 70,000 cycles. Thus, the superior shift characteristics of power transmitting fluids of this invention has been demonstrated The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected herein is not to be construed as Iimited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from the spirit of the invention.

Claims: WHAT IS CLAIMED IS: 1. A power transmitting fluid composition comprising: (1 ) a major amount of a lubricating oil, and (2) a shift-durability improving effective amount of an additive combination comprising: (a) an amine phosphate; and (b) a neutral or acidic friction modifier. 2. The composition of claim 1 , where the lubricating oil is a mineral oil, poly-α-olefin, or mixtures thereof. 3. The composition of claim 2, where the amine phosphate is a neutralisation or partial neutralisation product of an aliphatic primary amine and a hydroxy-substituted triester of a phosphorothioic acid treated with an inorganic phosphorus reagent. 4. The composition of claim 3, where the friction modifier is a full or partial alcoholic ester of a mono- or polycarboxylic acid. 5. The composition of claim 4, where the additive combination further comprises mercapto- and hydrocarbylthio-disubstituted derivatives of 1 ,3,4- thiadiazole and their mixtures. 6. The composition of claim 5, where the additive combination further comprises an antioxidant that is ashless, metal-containing, a 2S5 treated terpene derivative, or mixtures thereof. 7. The composition of claim 6, where the composition is a manual transmission fluid. 8. An additive concentrate comprising a major amount of the additive combination of claim 1 with other desired lubricating oil additive and a minor amount of lubricating oil. 9. A method of improving the shift durability of a power transmitting fluid by incorporating into the fluid a shift-durability improving effective amount of the additive concentrate of claim 8.

Inventors: DOWLING MICHAEL, HUMPHREY ROBERT WALTER, REEVE PHILIP, DOWLING, MICHAEL, HUMPHREY, ROBERT, WALTER, REEVE, PHILIP
Applicants: DOWLING MICHAEL, EXXON CHEMICAL PATENTS INC, HUMPHREY ROBERT WALTER, REEVE PHILIP, DOWLING, MICHAEL, EXXON CHEMICAL PATENTS INC., HUMPHREY, ROBERT, WALTER, REEVE, PHILIP
Application year: 1996
Main classification: C10M141
IPC codes: C10M107, C10M135, C10M137, C10M141, C10M145, C10M163, C10M169, C10N30, C10N40