Patent Description:
A functional fluid is a term which encompasses a variety of fluids including but not limited to tractor hydraulic fluids, power transmission fluids including automatic transmission fluids, continuously variable transmission fluids and manual transmission fluids, hydraulic fluids, gear oils, power steering fluids, fluids used in wind turbines and fluids related to power train components. It should be noted that within each of these fluids such as, for example, automatic transmission fluids, there are a variety of different types of fluids due to the various transmissions having different designs which have led to the need for fluids of markedly different functional characteristics.

With respect to tractor hydraulic fluids, these fluids are all-purpose (or multipurpose) products used for all lubricant applications in a tractor except for lubricating the engine. Also included as a tractor hydraulic fluid for the purposes of this invention are so-called Super Tractor Oil Universal fluids or "STOU" fluids, which also lubricate the engine. These lubricating applications may include lubrication of gearboxes, power take-off and clutch(es), rear axles, reduction gears, wet brakes, and hydraulic accessories. The components included within a tractor fluid must be carefully chosen so that the final resulting fluid composition will provide all the necessary characteristics required in the different applications. Such characteristics may include the ability to provide proper frictional properties for preventing wet brake and/or clutch chatter of oil immersed brakes and clutches while simultaneously providing the ability to actuate wet brakes and clutches, particularly provide power take-off (PTO) clutch performance. A tractor fluid must provide sufficient antiwear and extreme pressure properties as well as water tolerance/filterability capabilities. The extreme pressure (EP) properties of tractor fluids, important in gearing applications, may be demonstrated by the ability of the fluid to pass a spiral bevel test as well as a straight spur gear test. The tractor fluid may need to pass wet brake chatter tests while providing adequate wet brake capacity when used in oil immersed disk brakes which are comprised of cellulose, bronze, graphitic-compositions and asbestos, among other materials. The tractor fluid may need to demonstrate its ability to provide friction retention for power shift transmission clutches such as those clutches which include, cellulose and graphitic clutches, among other materials.

When the functional fluid is a tractor hydraulic fluid, the fluids must have enough friction for the system to operate effectively. The term "friction durability" will be used to describe the property of the fluid to retain its original frictional properties. For example, a fluid with good friction durability will exhibit small changes in the frictional properties during its useful life. It is important that the tractor hydraulic fluid maintains its frictional properties throughout its life to ensure optimal operation of brakes and clutches.

The present disclosure generally relates to lubricating oil compositions which improve or maintain frictional durability while maintaining low torque variation at low speed when used as tractor hydraulic fluids. <CIT> describes a lubricating oil composition suited for use in lubricating a driveline device which includes an oil of lubricating viscosity and a compound comprising a polyolefin-substituted bridged hydroxyaromatic compound or metal salt thereof. <CIT> describes a functional fluid comprising a major amount of an oil of lubricating viscosity and at least about <NUM> wt-% glycerol.

The present invention is defined in and by the appended claims. In accordance with claim <NUM>, there is provided a tractor hydraulic fluid composition which comprises:.

wherein the high overbased phenate detergent is a calcium phenate detergent, and wherein the composition comprises from <NUM> to <NUM> wt. % Ca from the high overbased phenate detergent.

Also provided, in accordance with claim <NUM>, is a method of improving brake and clutch capacity while maintaining low torque variation at low speed of a tractor hydraulic system comprising lubricating said hydraulic system with a lubricating oil composition according to any of claims <NUM> to <NUM>.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

As used herein, the following terms have the following meanings, unless expressly stated to the contrary. In this specification, the following words and expressions, if and when used, have the meanings given below.

A "major amount" means in excess of <NUM> weight % of a composition.

A "minor amount" means less than <NUM> weight % of a composition, expressed in respect of the stated additive and in respect of the total mass of all the additives present in the composition, reckoned as active ingredient of the additive or additives.

"Active ingredients" or "actives" or "oil free" refers to additive material that is not diluent or solvent.

The abbreviation "ppm" means parts per million by weight, based on the total weight of the lubricating oil composition.

Total base number (TBN) was determined in accordance with ASTM D2896. TBN numbers are reported on an "actives" or "oil-free" basis.

Metal - The term "metal" refers to alkali metals, alkaline earth metals, or mixtures thereof.

Kinematic viscosity at <NUM> (KV<NUM>) was determined in accordance with ASTM D445.

Olefins - The term "olefins" refers to a class of unsaturated aliphatic hydrocarbons having one or more carbon-carbon double bonds, obtained by a number of processes. Those containing one double bond are called mono-alkenes, and those with two double bonds are called dienes, alkyldienes, or diolefins. Alpha olefins are particularly reactive because the double bond is between the first and second carbons. Examples are <NUM>-octene and <NUM>-octadecene, which are used as the starting point for medium-biodegradable surfactants. Linear and branched olefins are also included in the definition of olefins.

Normal Alpha Olefins - The term "Normal Alpha Olefins" refers to olefins which are straight chain, non-branched hydrocarbons with carbon-carbon double bond present in beginning and end of the chain.

Isomerized Normal Alpha Olefin. The term "Isomerized Normal Alpha Olefin" as used herein refers to an alpha olefin that has been subjected to isomerization conditions which results in an alteration of the distribution of the olefin species present and/or the introduction of branching along the alkyl chain. The isomerized olefin product may be obtained by isomerizing a linear alpha olefin containing from about <NUM> to about <NUM> carbon atoms, preferably from about <NUM> to about <NUM> carbon atoms, and preferably from about <NUM> to about <NUM> carbon atoms.

All ASTM standards referred to herein are the most current versions as of the filing date of the present application.

In one aspect, the lubricating oil composition of the present disclosure improves frictional durability while maintaining low torque variation at low speed when used as a tractor hydraulic fluid. In another aspect, the lubricating oil composition of the present disclosure maintains frictional durability while maintaining low torque variation at low speed when used as a tractor hydraulic fluid.

In accordance with claim <NUM>, the lubricating oil composition of the present disclosure comprises a detergent system comprising: a low overbased sulfonate detergent, a high overbased sulfonate detergent; and a high overbased phenate detergent.

In another aspect, the detergent system of the present disclosure provides synergistic performance benefits when used in lubricating oil compositions for tractor hydraulic fluids.

A base oil is useful for making concentrates as well as for making lubricating oil compositions therefrom, and may be selected from natural and synthetic lubricating oils and combinations thereof.

Natural oils include animal and vegetable oils, liquid petroleum oils and hydrorefined, solvent-treated mineral lubricating oils of the paraffinic, naphthenic and mixed paraffinic-naphthenic types. Oils of lubricating viscosity derived from coal or shale are also useful base oils.

Synthetic lubricating oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(<NUM>-hexenes), poly(<NUM>-octenes), poly(<NUM>-decenes); alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(<NUM>-ethylhexyl)benzenes; polyphenols (e.g., biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogues and homologues thereof.

Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g., malonic acid, alkyl malonic acids, alkenyl malonic acids, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, fumaric acid, azelaic acid, suberic acid, sebacic acid, adipic acid, linoleic acid dimer, phthalic acid) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, <NUM>-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol). Specific examples of these esters include dibutyl adipate, di(<NUM>-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the <NUM>-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of <NUM>-ethylhexanoic acid.

Esters useful as synthetic oils also include those made from C<NUM> to C<NUM> monocarboxylic acids and polyols, and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol.

Unrefined, refined and re-refined oils can be used in the present lubricating oil composition. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation or ester oil obtained directly from an esterification process and used without further treatment would be unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques, such as distillation, solvent extraction, acid or base extraction, filtration and percolation are known to those skilled in the art.

Re-refined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such re-refined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques for approval of spent additive and oil breakdown products.

Base oils suitable for use herein are any of the variety corresponding to API Group II, Group III, Group IV, and Group V oils and combinations thereof, preferably the Group III to Group V oils due to their exceptional volatility, stability, viscometric and cleanliness features.

The oil of lubricating viscosity for use in the lubricating oil compositions of this disclosure, also referred to as a base oil, is typically present in a major amount, e.g., an amount of greater than <NUM> wt. %, preferably greater than about <NUM> wt. %, more preferably from about <NUM> to about <NUM> wt. % and most preferably from about <NUM> to about <NUM> wt. %, based on the total weight of the composition. The expression "base oil" as used herein shall be understood to mean a base stock or blend of base stocks which is a lubricant component that is produced by a single manufacturer to the same specifications (independent of feed source or manufacturer's location); that meets the same manufacturer's specification; and that is identified by a unique formula, product identification number, or both. The base oil for use herein can be any presently known or later-discovered oil of lubricating viscosity used in formulating lubricating oil compositions for any and all such applications, e.g., engine oils, marine cylinder oils, functional fluids such as hydraulic oils, gear oils, transmission fluids, etc. Additionally, the base oils for use herein can optionally contain viscosity index improvers, e.g., polymeric alkylmethacrylates; olefinic copolymers, e.g., an ethylene-propylene copolymer or a styrenebutadiene copolymer; and the like and mixtures thereof.

As one skilled in the art would readily appreciate, the viscosity of the base oil is dependent upon the application. Accordingly, the viscosity of a base oil for use herein will ordinarily range from about <NUM> to about <NUM> centistokes (cSt) at <NUM>° Centigrade (C. Generally, individually the base oils used as engine oils will have a kinematic viscosity range at <NUM>° C. of about <NUM> cSt to about <NUM> cSt, preferably about <NUM> cSt to about <NUM> cSt, and most preferably about <NUM> cSt to about <NUM> cSt and will be selected or blended depending on the desired end use and the additives in the finished oil to give the desired grade of engine oil, e.g., a lubricating oil composition having an SAE Viscosity Grade of 0W, 0W-<NUM>, 0W-<NUM>, 0W-<NUM>, 0W-<NUM>, 0W-<NUM>, 0W-<NUM>, 0W-<NUM>, 0W-<NUM>, 0W-<NUM>, 5W, 5W-<NUM>, 5W-<NUM>, 5W-<NUM>, 5W-<NUM>, 5W-<NUM>, 10W, 10W-<NUM>, 10W-<NUM>, 10W-<NUM>, 10W-<NUM>, 15W, 15W-<NUM>, 15W-<NUM>, 15W-<NUM>, <NUM>, <NUM>, <NUM>, <NUM> and the like. Also, oils could be blended in viscosity grades specific to tractor hydraulic fluids such as J20C and/or J20D.

The compositions described herein comprise low overbased alkaryl sulfonate salts. In embodiments, the compositions comprise:.

These low overbased alkaryl sulfonate calcium salts can serve, e.g., as detergents and friction providers in the compositions described herein.

In some embodiments, the low overbased alkaryl sulfonate detergent is derived from an alkali metal, an alkaline earth metal, or mixtures thereof.

In some embodiments, the at least one low overbased alkaryl sulfonate calcium salt having an alkaryl group that is an aryl group substituted with an alkyl group derived from propylene or isobutylene oligomers has the following formula A:
<CHM>
wherein R is an alkyl group derived from propylene or isobutylene oligomers;
RX is hydrogen or methyl, m is <NUM> to <NUM>; and n is <NUM> or greater. In some embodiments, m is <NUM>-<NUM>. In some embodiments, n is <NUM>. In some embodiments, the alkyl group has <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM> carbons. In some embodiments, the alkyl group is derived from propylene oligomers.

In some embodiments, the at least one low overbased alkaryl sulfonate calcium salt having an alkaryl group that is an aryl group substituted with an alkyl group derived from at least one normal alpha olefin or an isomerized normal alpha olefin, said olefin having from about <NUM> to about <NUM> carbon atoms, has the following structure B:
<CHM>
wherein R is an alkyl group derived from at least one normal alpha olefin or an isomerized normal alpha olefin, said olefin having from about <NUM> to about <NUM> carbon atoms;
RX is hydrogen or methyl, m is <NUM> to <NUM>; and n is <NUM> or greater. In some embodiments, m is <NUM>-<NUM>. In some embodiments, n is <NUM>.

In some embodiments, each of the low overbased alkaryl sulfonate calcium salts (A) or (B) above is a low overbased alkyl-substituted benzene or low overbased alkyl-substituted toluene sulfonate calcium salt.

The calcium content accounted for by the at least one low overbased alkaryl sulfonate calcium salt (A) or (B) present in the oil composition is <NUM> to <NUM> weight percent of the lubricating oil composition. In some embodiments, the calcium content is <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM> weight percent of the lubricating oil.

In some embodiments, the low overbased alkaryl sulfonate calcium salt (B) is one wherein the alkaryl group is an aryl group substituted with an alkyl group derived from at least one normal alpha olefin or an isomerized normal alpha olefin, said olefin having from about <NUM> to about <NUM> carbon atoms.

In some embodiments, each or both of the alkaryl sulfonate calcium salts (A) or (B) is low overbased, wherein the TBN is less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, or less than <NUM>. In some embodiments, each or both of the alkyaryl sulfonate calcium salts (A) or (B) has a TBN of <NUM>-<NUM>, <NUM>-<NUM>, or <NUM>-<NUM>.

The lubricating oil composition of the present invention contains one or more high overbased sulfonate detergents having a TBN of <NUM>-<NUM>, for example, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> KOH/g on an actives basis.

Sulfonates may be prepared from sulfonic acids which are typically obtained by the sulfonation of alkyl substituted aromatic hydrocarbons such as those obtained from the fractionation of petroleum or by the alkylation of aromatic hydrocarbons. Examples included those obtained by alkylating benzene, toluene, xylene, naphthalene, diphenyl or their halogen derivatives. The alkylation may be carried out in the presence of a catalyst with alkylating agents having from about <NUM> to more than <NUM> carbon atoms. The alkaryl sulfonates usually contain from about <NUM> to about <NUM> or more carbon atoms, preferably from about <NUM> to about <NUM> carbon atoms, preferably about <NUM> to <NUM> carbon atoms, and more preferably <NUM>-<NUM> carbon atoms per alkyl substituted aromatic moiety.

In some embodiments, the high overbased detergent is a high overbased alkaryl sulfonate calcium detergent. In some embodiments, the calcium content of the high overbased detergent is <NUM> to <NUM>, <NUM><NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>; <NUM> to <NUM>, <NUM> to <NUM> weight percent of the lubricating oil composition.

The high overbased phenate detergent is a phenolic-based detergent. The phenolic-based detergent is an isomerized olefin phenate detergent.

The high overbased phenate detergent has a TBN of <NUM>-<NUM>, for example, <NUM>-<NUM>,<NUM>-<NUM>, <NUM>- <NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> mgKOH/gram on an oil free basis.

The phenolic-based detergent is an alkylated phenate detergent wherein the alkyl group is derived from an isomerized normal alpha olefin having from <NUM> to <NUM> carbon atoms per molecule.

The phenolic-based detergent has an isomerization level (I) of the normal alpha olefin is between from <NUM> to <NUM>, preferably from <NUM> to about <NUM>, preferably from about <NUM> to about <NUM>, and more preferably from about <NUM> to about <NUM>.

In one aspect of the present disclosure, the phenate detergent is a sulfurized phenate detergent.

In one aspect of the present disclosure, the isomerized olefin phenate detergent can be prepared as described in <CIT>.

In one aspect of the present disclosure, the alkyl group is derived from an isomerized alpha olefin having from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, <NUM> to about <NUM>, or from about <NUM> to about <NUM> carbon atoms per molecule.

In another embodiment, the isomerization level of the alpha olefin is about <NUM>, and having from about <NUM> to about <NUM> carbon atoms.

The calcium content of the high overbased phenate detergent is from <NUM> to <NUM>, for example, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM> weight percent, based on the weight of the oil composition.

Other detergents that may be used include oil-soluble overbased sulfonate, salixarate, salicylate, saligenin, complex detergents and naphthenate detergents and other oil-soluble alkylhydroxybenzoates of a metal, particularly the alkali or alkaline earth metals, e.g., barium, sodium, potassium, lithium, calcium, and magnesium. The most commonly used metals are calcium and magnesium, which may both be present in detergents used in a lubricant, and mixtures of calcium and/or magnesium with sodium.

Overbased metal detergents are generally produced by carbonating a mixture of hydrocarbons, detergent acid, for example: sulfonic acid, alkylhydroxybenzoate etc., metal oxide or hydroxides (for example calcium oxide or calcium hydroxide) and promoters such as xylene, methanol and water. For example, for preparing an overbased calcium sulfonate, in carbonation, the calcium oxide or hydroxide reacts with the gaseous carbon dioxide to form calcium carbonate. The sulfonic acid is neutralized with an excess of CaO or Ca(OH)<NUM>, to form the sulfonate.

Overbased detergents may be low overbased, e.g., an overbased salt having a TBN below <NUM> on an actives basis. In one embodiment, the TBN of a low overbased salt may be from about <NUM> to about <NUM>. In another embodiment, the TBN of a low overbased salt may be from about <NUM> to about <NUM>. Overbased detergents may be medium overbased, e.g., an overbased salt having a TBN from about <NUM> to about <NUM>. In one embodiment, the TBN of a medium overbased salt may be from about <NUM> to about <NUM>. In another embodiment, the TBN of a medium overbased salt may be from about <NUM> to about <NUM>. Overbased detergents may be high overbased, e.g., an overbased salt having a TBN above <NUM>. In one embodiment, the TBN of a high overbased salt may be from about <NUM> to about <NUM> on an actives basis.

In one embodiment, the detergent can be one or more alkali or alkaline earth metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid. Suitable hydroxyaromatic compounds include mononuclear monohydroxy and polyhydroxy aromatic hydrocarbons having <NUM> to <NUM>, and preferably <NUM> to <NUM>, hydroxyl groups. Suitable hydroxyaromatic compounds include phenol, catechol, resorcinol, hydroquinone, pyrogallol, cresol, and the like. The preferred hydroxyaromatic compound is phenol.

The alkyl substituted moiety of the alkali or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid is derived from an alpha olefin having from about <NUM> to about <NUM> carbon atoms. The olefins employed may be linear, isomerized linear, branched or partially branched linear. The olefin may be a mixture of linear olefins, a mixture of isomerized linear olefins, a mixture of branched olefins, a mixture of partially branched linear or a mixture of any of the foregoing.

In one embodiment, the mixture of linear olefins that may be used is a mixture of normal alpha olefins selected from olefins having from about <NUM> to about <NUM> carbon atoms per molecule. In one embodiment, the normal alpha olefins are isomerized using at least one of a solid or liquid catalyst.

In one embodiment, at least about <NUM> mole%, at least about <NUM> mole%, at least about <NUM> mole%, at least about <NUM> mole%, at least about <NUM> mole%, at least about <NUM> mole% of the alkyl groups contained within the alkali or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid such as the alkyl groups of an alkaline earth metal salt of an alkyl-substituted hydroxybenzoic acid detergent are a C<NUM> or higher. In another embodiment, the alkali or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid is an alkali or alkaline earth metal salt of an alkyl-substituted hydroxybenzoic acid that is derived from an alkyl-substituted hydroxybenzoic acid in which the alkyl groups are C<NUM> to about C<NUM> normal alpha-olefins. In another embodiment, the alkyl group is derived from at least two alkylated phenols. The alkyl group on at least one of the at least two alkyl phenols is derived from an isomerized alpha olefin. The alkyl group on the second alkyl phenol may be derived from branched or partially branched olefins, highly isomerized olefins or mixtures thereof.

In another embodiment, the alkali or alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid is a salicylate derived from an alkyl group with <NUM>-<NUM> carbon atoms, preferably <NUM>-<NUM> carbon atoms, more preferably, isomerized <NUM>-<NUM> NAO.

The lubricating oil composition disclosed herein can comprise one or more antiwear agent. Antiwear agents reduce wear of metal parts. Suitable anti-wear agents include dihydrocarbyl dithiophosphate metal salts such as zinc dihydrocarbyl dithiophosphates (ZDDP) of formula (Formula <NUM>):.

Zn[S-P(=S)(OR<NUM>)(OR<NUM>)]<NUM>     Formula <NUM>,.

wherein R<NUM> and R<NUM> may be the same of different hydrocarbyl radicals having from <NUM> to <NUM> (e.g., <NUM> to <NUM>) carbon atoms and including radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl and cycloaliphatic radicals. Particularly preferred as R<NUM> and R<NUM> groups are alkyl groups having from <NUM> to <NUM> carbon atoms (e.g., the alkyl radicals may be ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, <NUM>-ethylhexyl). In order to obtain oil solubility, the total number of carbon atoms (i.e., R<NUM>+R<NUM>) will be at least <NUM>. The zinc dihydrocarbyl dithiophosphate can therefore comprise zinc dialkyl dithiophosphates. The zinc dialkyl dithiophosphate is a primary, secondary zinc dialkyl dithiophosphate, or a combination thereof. ZDDP may be present at <NUM> wt. % or less (e.g., <NUM> to <NUM> wt. %, or <NUM> to <NUM> wt %) of the lubricating oil composition.

The lubricating oil composition disclosed herein can comprise one or more antioxidant. Antioxidants reduce the tendency of mineral oils during to deteriorate during service. Oxidative deterioration can be evidenced by sludge in the lubricant, varnish-like deposits on the metal surfaces, and by viscosity growth. Suitable antioxidants include hindered phenols, aromatic amines, hindered amines (also known as HALS-Hindered Amine light Stabilizers) and sulfurized alkylphenols and alkali and alkaline earth metals salts thereof.

The hindered amines used in this invention are of many types, with three types predominating: pyrimidines, piperidines and stable nitroxide compounds. Many more are described in the book "<NPL> and in Patents such as <CIT>.

The hindered phenol antioxidant often contains a secondary butyl and/or a tertiary butyl group as a sterically hindering group. The phenol group may be further substituted with a hydrocarbyl group (typically linear or branched alkyl) and/or a bridging group linking to a second aromatic group. Examples of suitable hindered phenol antioxidants include <NUM>,<NUM>-di-tert-butylphenol; <NUM>-methyl-<NUM>,<NUM>-di-tert-butylphenol; <NUM>-ethyl-<NUM>,<NUM>-di-tert-butylphenol; <NUM>-propyl-<NUM>,<NUM>-di-tert-butylphenol; <NUM>-butyl-<NUM>,<NUM>-di-tert-butylphenol; and <NUM>-dodecyl-<NUM>,<NUM>-di-tertbutylphenol. Other useful hindered phenol antioxidants include <NUM>,<NUM>-di-alkyl-phenolic propionic ester derivatives such as IRGANOX® L-<NUM> from Ciba and bis-phenolic antioxidants such as <NUM>,<NUM>'-bis(<NUM>,<NUM>-di-tert-butylphenol) and <NUM>,<NUM>'-methylenebis(<NUM>,<NUM>-di-tert-butylphenol). Typical aromatic amine antioxidants have at least two aromatic groups attached directly to one amine nitrogen. Typical aromatic amine antioxidants have alkyl substituent groups of at least <NUM> carbon atoms. Particular examples of aromatic amine antioxidants useful herein include <NUM>,<NUM>'-dioctyldiphenylamine, <NUM>,<NUM>'-dinonyldiphenylamine, N-phenyl-<NUM>-naphthylamine, N-(<NUM>-tert-octyphenyl)-<NUM>-naphthylamine, and N-(<NUM>-octylphenyl)-<NUM>-naphthylamine. Antioxidants may be present at <NUM> to <NUM> wt. % (e.g., <NUM> to <NUM> wt. %) of the lubricating oil composition.

The lubricating oil composition disclosed herein can comprise one or more dispersant. Dispersants maintain in suspension materials resulting from oxidation that are insoluble in oil, thus preventing sludge flocculation and precipitation or deposition on metal parts. Dispersants useful herein include nitrogen-containing, ashless (metal-free) dispersants known to effective to reduce formation of deposits upon use in gasoline and diesel engines.

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. Also suitable are condensation products of polyamines and hydrocarbyl-substituted phenyl acids. Mixtures of these dispersants can also be used. Basic nitrogen-containing ashless dispersants are well-known lubricating oil additives and methods for their preparation are extensively described in the patent literature. Preferred dispersants are the alkenyl succinimides and succinamides where the alkenyl-substituent is a long-chain of preferably greater than <NUM> carbon atoms. These materials are readily made by reacting a hydrocarbyl-substituted dicarboxylic acid material with a molecule containing amine functionality. Examples of suitable amines are polyamines such as polyalkylene polyamines, hydroxy-substituted polyamines and polyoxyalkylene polyamines.

Particularly preferred ashless dispersants are the polyisobutenyl succinimides formed from polyisobutenyl succinic anhydride and a polyalkylene polyamine such as a polyethylene polyamine of formula <NUM>:.

NH<NUM>(CH<NUM>CH<NUM>NH)zH     Formula <NUM>,.

wherein z is <NUM> to <NUM>. The polyisobutenyl group is derived from polyisobutene and preferably has a number average molecular weight (Mn) in a range of <NUM> to <NUM> Daltons (e.g., <NUM> to <NUM> Daltons). For example, the polyisobutenyl succinimide may be a mono-succinimide or a bis-succinimide derived from a polyisobutenyl group having a Mn of <NUM> to <NUM> Daltons. As is known in the art, the dispersants may be post-treated (e.g., with a boronating agent or a cyclic carbonate, ethylene carbonate etc).

Nitrogen-containing ashless (metal-free) dispersants are basic, and contribute to the TBN of a lubricating oil composition to which they are added, without introducing additional sulfated ash. Dispersants may be present at <NUM> to <NUM> wt. % (e.g., <NUM> to <NUM> wt. %) of the lubricating oil composition.

The lubricating oil composition disclosed herein can comprise one or more foam inhibitor that can break up foams in oils. Non-limiting examples of suitable foam inhibitors or anti-foam inhibitors include silicone oils or polydimethylsiloxanes, fluorosilicones, alkoxylated aliphatic acids, polyethers (e.g., polyethylene glycols), branched polyvinyl ethers, alkyl acrylate polymers, alkyl methacrylate polymers, polyalkoxyamines and combinations thereof.

The lubricating oil compositions of the present disclosure may also contain other conventional additives that can impart or improve any desirable property of the lubricating oil composition in which these additives are dispersed or dissolved. Any additive known to a person of ordinary skill in the art may be used in the lubricating oil compositions disclosed herein. Some suitable additives have been described in <NPL>); and <NPL>). For example, the lubricating oil compositions can be blended with antioxidants, anti-wear agents, detergents such as metal detergents, rust inhibitors, dehazing agents, demulsifying agents, metal deactivating agents, friction modifiers, pour point depressants, antifoaming agents, cosolvents, corrosion-inhibitors, ashless dispersants, multifunctional agents, dyes, extreme pressure agents and the like and mixtures thereof. A variety of the additives are known and commercially available. These additives, or their analogous compounds, can be employed for the preparation of the lubricating oil compositions of the disclosure by the usual blending procedures.

Usually these concentrates may be diluted with <NUM> to <NUM>, e.g., <NUM> to <NUM>, parts by weight of lubricating oil per part by weight of the additive package in forming finished lubricants, e.g. tractor hydraulic fluids.

Each of the foregoing additives, when used, is used at a functionally effective amount to impart the desired properties to the lubricant. Thus, for example, if an additive is a friction modifier, a functionally effective amount of this friction modifier would be an amount sufficient to impart the desired friction modifying characteristics to the lubricant.

In general, the concentration of each of the additives in the lubricating oil composition, when used, may range from about <NUM> wt. % to about <NUM> wt. %, from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, based on the total weight of the lubricating oil composition. Further, the total amount of the additives in the lubricating oil composition may range from about <NUM> wt. % to about <NUM> wt. %, from about <NUM> wt. % to about <NUM> wt. %, or from about <NUM> wt. % to about <NUM> wt. %, based on the total weight of the lubricating oil composition.

The following examples are presented to exemplify embodiments of the invention but are not intended to limit the invention to the specific embodiments set forth. Unless indicated to the contrary, all parts and percentages are by weight. All numerical values are approximate. When numerical ranges are given, it should be understood that embodiments outside the stated ranges may still fall within the scope of the invention. Specific details described in each example should not be construed as necessary features of the invention.

The isomerization level (I) of the olefin was determined by hydrogen-<NUM> (<NUM>) NMR. The NMR spectra were obtained on a Bruker Ultrashield Plus <NUM> in chloroform-d1 at <NUM> using TopSpin <NUM> spectral processing software.

The isomerization level (I) represents the relative amount of methyl groups (-CH3) (chemical shift <NUM>-<NUM> ppm) attached to the methylene backbone groups (-CH2-) (chemical shift <NUM>-<NUM> ppm) and is defined by Equation (<NUM>) as shown below, <MAT> where m is NMR integral for methyl groups with chemical shifts between <NUM> ± <NUM> to <NUM> ± <NUM> ppm, and n is NMR integral for methylene groups with chemical shifts between <NUM> ± <NUM> to <NUM> ± <NUM> ppm.

The isomerized level (I) of the alpha olefin is between from about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM>, more preferably from about <NUM> to about <NUM>.

In one embodiment, the isomerization level of the NAO is about <NUM>, and having from about <NUM> to about <NUM> carbon atoms.

In another embodiment, the isomerization level of the NAO is about <NUM>, and having from about <NUM> to about <NUM> carbon atoms.

Provided herein are Tractor Hydraulic Fluid Compositions which are envisioned for the present disclosure. Examples of the disclosure will generally include test formulations disclosed in Table <NUM> below.

Examples of the disclosure will generally include test formulations disclosed in Table <NUM> below.

The test formulations in Table <NUM> were evaluated in the R20 test which is an axle brake screener test. It is a friction endurance test that tracks friction coefficients and brake noise at various friction plate engagement steps that include multiple pressures and speeds. This test is part of the ZF TE-ML 05E and TE-ML 05F specifications for axles of off-road vehicles from ZF Friedrichshafen AG, Friedrichshafen, Germany, and is available there.

The results of the R20 test are in Table <NUM> below.

Claim 1:
A tractor hydraulic fluid composition comprising:
(a) a major amount of an oil of lubricating viscosity, and
(b) a detergent system comprising:
(i) a low overbased alkaryl sulfonate detergent having a total base number of <NUM> to less than <NUM>, the total base number determined in accordance with ASTM D2896;
(ii) a high overbased sulfonate detergent having a total base number of <NUM>-<NUM> KOH/g on an actives basis, the total base number determined in accordance with ASTM D2896; and
(iii) a high overbased phenate detergent having an alkyl group derived from an isomerized normal alpha olefin having from about <NUM> to about <NUM> carbon atoms per molecule, the high overbased phenate detergent having a total base number of <NUM>-<NUM> KOH/g on an oil free basis, the total base number determined in accordance with ASTM D2896, and wherein the high overbased phenate detergent has an isomerization level (I) of the normal alpha olefin of from <NUM> to <NUM>, wherein I is determined by hydrogen-<NUM> (<NUM>) NMR using the equation <MAT> where m is NMR integral for methyl groups with chemical shifts between <NUM> ± <NUM> to <NUM> ± <NUM> ppm, and n is NMR integral for methylene groups with chemical shifts between <NUM> ± <NUM> to <NUM> ± <NUM> ppm,
wherein the high overbased phenate detergent is a calcium phenate detergent, and wherein the composition comprises from <NUM> to <NUM> wt.% Ca from the high overbased phenate detergent.