Anti-wear system for improved copper corrosion

Abstract

To provide an oil-soluble phosphorus antiwear additive, and a lubricating composition comprising an ashless antiwear additive improved in terms of copper corrosion performance.SOLUTION: A lubricating composition comprises: a majority of one or more base oils of lubricating viscosity; and an oil-soluble phosphorus antiwear additive made by a process comprising the steps of (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product, (b) distilling the reaction product and recovering a condensate, and (c) reacting the condensate with an unsaturated ester of a carboxylic acid to form the oil-soluble phosphorus antiwear additive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to lubricating compositions having an oil-soluble phosphorus anti-wear additive with improved copper corrosion. [Background technology]

[0002] Lubricating compositions are designed to balance low wear and low friction while minimizing other performance drawbacks. For example, zinc dialkyldithiophosphates, commonly known as ZDDPs, are widely used anti-wear additives in lubricants such as engine oils, transmission fluids, and / or hydraulic fluids. However, the zinc provided by such additives can be less desirable in some applications, leading to the increased use of so-called ashless or metal-free anti-wear additives. Ashless (i.e., metal-free) dithiophosphates are one such alternative, but while ashless dithiophosphates have good anti-wear and extreme pressure performance, these additives tend to be corrosive to metals, especially copper and bronze metals. Summary of the Invention

[0003] In one approach or embodiment, a lubricating composition comprising a majority of one or more base oils of lubricating viscosity and an oil-soluble phosphorus anti-wear additive produced by a process comprising the steps of: (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; (b) distilling the reaction product and recovering a condensate; and (c) reacting the condensate with an unsaturated ester of a carboxylic acid to form the oil-soluble phosphorus anti-wear additive.

[0004] In other approaches or embodiments, the lubricating compositions described in the preceding paragraph may include one or more optional features or embodiments in any combination. These optional features or embodiments may include one or more of the following: the distillation is carried out at one or more of a temperature of at least about 50°C, a pressure of at least about 0.1 Torr, or a combination thereof, and / or the condensate is recovered at a temperature of about 10°C or less, and / or the distillation is carried out in a falling film evaporator, a thin film evaporator, a centrifugal thin film evaporator, a short stroke evaporator, or a combination thereof, and / or the condensate comprises a dialkyl dithiophosphoric acid, and / or the dialkyl dithiophosphoric acid is dipropyl dithiophosphoric acid, diisopropyl dithiophosphoric acid, dibutyl dithiophosphoric acid, diisobutyl dithiophosphoric acid, or a combination thereof, and / or the unsaturated ester of a carboxylic acid is a C1-C20 alkyl (meth)acrylate, and / or the unsaturated ester of a carboxylic acid is methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, or a combination thereof, and / or the organic hydroxy compound is a C1-C6 linear or branched alcohol, a hydroxyl aryl compound, or a mixture thereof, and / or the organic hydroxy compound is methyl alcohol, and / or the organic hydroxy compound is ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, phenol, naphthol, amyl alcohol, hexyl alcohol, isohexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol, octadecyl alcohol, 2-ethylhexyl alcohol, 4-methyl-2-pentyl alcohol, phenyl alcohol, butylphenyl alcohol, cyclohexyl alcohol, methylcyclopentyl alcohol, propenyl alcohol, butenyl alcohol, or a combination thereof; and / or the organic hydroxy compound is isopropyl alcohol; the reaction product comprises diisopropyl dithiophosphoric acid and one or more phosphorus polysulfides; the condensate comprises diisopropyl dithiophosphoric acid and is substantially free of the one or more phosphorus polysulfides; the condensate is further reacted with ethyl acrylate to form an oil-soluble phosphorus antiwear additive; and / or the lubricating composition has a pH of about 0.5.The composition includes 1 to about 5 weight percent of an oil-soluble phosphorus antiwear additive, and / or an organic hydroxy compound is provided in a molar ratio of about 4:1 to about 10:1 relative to the phosphorus pentasulfide, and / or an unsaturated ester of a carboxylic acid is provided in a molar ratio of about 0.1:1 to about 0.5:1 relative to the organic hydroxy compound.

[0005] In another approach or embodiment, described herein is a method for preparing an oil-soluble phosphorus anti-wear additive, the method comprising reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product, distilling the reaction product and recovering a condensate therefrom, and reacting the condensate with an unsaturated ester of a carboxylic acid to form the oil-soluble phosphorus anti-wear additive.

[0006] In other approaches or embodiments, the method of the preceding paragraph may be combined with one or more optional features, steps, or embodiments in any combination. These optional features, steps, or embodiments may include one or more of the following:the distillation is carried out at a temperature of at least about 50°C, and / or the distillation is carried out at a pressure of at least about 0.1 Torr, and / or the condensate is collected at a temperature of about 10°C or less, and / or the distillation is carried out in a falling film evaporator, a thin film evaporator, a centrifugal thin film evaporator, a short path evaporator, or a combination thereof, and / or the condensate comprises a dialkyl dithiophosphoric acid, and / or the dialkyl dithiophosphoric acid is dipropyl dithiophosphoric acid, diisopropyl dithiophosphoric acid, dibutyl dithiophosphoric acid, diisobutyl dithiophosphoric acid, or a combination thereof, and / or the unsaturated ester of carboxylic acid is a C1 to C20 alkyl (meth)acrylate, and / or the unsaturated ester of carboxylic acid is methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, or a combination thereof, and / or the organic hydroxy compound is a C1 to C6 linear or branched alcohol, a hydroxyaryl compound, or a mixture thereof, and / or the organic hydroxy compound is methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, butyl alcohol, tert-butyl alcohol, sec-butyl alcohol, phenol, naphthol, amyl alcohol, hexyl alcohol, iso-hexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol, octadecyl alcohol, 2-ethylhexyl alcohol, 4-methyl-2-pentyl alcohol, phenyl alcohol, butylphenyl alcohol, cyclohexyl alcohol, methylcyclopentyl alcohol, propenyl alcohol, butenyl alcohol, or combinations thereof, and / or organic hydrochlorides. the hydroxy compound is isopropyl alcohol, the reaction product comprises diisopropyl dithiophosphoric acid and one or more phosphorus polysulfides, the condensate comprises diisopropyl dithiophosphoric acid and is substantially free of one or more phosphorus polysulfides, the condensate is further reacted with ethyl acrylate to form an oil-soluble phosphorus anti-wear additive, and / or the organic hydroxy compound is provided in a molar ratio of about 4:1 to about 10:1 relative to the phosphorus pentasulfide, and / or the unsaturated ester of a carboxylic acid is provided in a molar ratio of about 0.1:1 to about 0.5:1 relative to the organic hydroxy compound.

[0007] In yet another approach or embodiment, an oil-soluble phosphorus antiwear additive is described herein and is made by a process comprising: (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; (b) distilling the reaction product and recovering a condensate therefrom; and (c) reacting the condensate with an unsaturated ester of a carboxylic acid to form the oil-soluble phosphorus antiwear additive. In other approaches or embodiments, the oil-soluble phosphorus antiwear additive may comprise any other embodiment of the lubricant or method described in this Summary.

[0008] In yet another approach or embodiment, described herein is the use of evaporation or distillation to recover a condensate from the reaction product of an organic hydroxy compound reacted with phosphorus pentasulfide, which condensate reacts with an unsaturated ester of a carboxylic acid to form an oil-soluble phosphorus antiwear additive. The use herein may include any further embodiments described in this Summary.

[0009] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. The following definitions are provided to clarify the meaning of certain terms used herein.

[0010] The terms "gear oil," "gear fluid," "gear lubricant," "base gear lubricant," "lubricating oil," "lubricant composition," "lubricating composition," "lubricant," and "lubricating fluid" refer to a finished lubricating product comprising a major amount of a base oil and a minor amount of an additive composition, as discussed herein. In one approach, such fluids are for use in extreme pressure conditions, such as in transmissions and gear drive components having metal-to-metal contact, for example, in transmissions and / or limited slip differentials. In another approach, such fluids are for use in engine lubrication.

[0011] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense, as is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having a predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from hydrocarbon substituents, where the substituted hydrocarbon substituents contain one or more of halo, hydroxyl, alkoxy, mercapto, nitro, nitroso, amino, pyridyl, furyl, imidazolyl, oxygen, and nitrogen, and no more than two non-hydrocarbon substituents are present for every 10 carbon atoms in the hydrocarbyl group.

[0012] As used herein, the term "percent by weight" or "wt%" means the percentage that the listed component represents relative to the weight of the entire composition, unless otherwise specified. All percentages herein are by weight unless otherwise specified.

[0013] The terms "soluble," "oil-soluble," or "dispersible" as used herein may, but do not necessarily, indicate that a compound or additive is soluble, dissolvable, miscible, or suspendable in oil in all proportions. However, the terms do mean that they are soluble, suspendable, dissolvable, or stably dispersible in oil to a sufficient degree to exert their intended effect in the environment in which the oil is used, for example. Furthermore, if desired, the incorporation of other additives may also allow for the incorporation of higher levels of the specific additive.

[0014] As used herein, the term "alkyl" refers to straight, branched, cyclic, and / or substituted saturated chain moieties of about 1 to about 200 carbon atoms. As used herein, the term "alkenyl" refers to straight, branched, cyclic, and / or substituted saturated chain moieties of about 3 to about 30 carbon atoms. As used herein, the term "aryl" refers to mono- and polycyclic aromatic compounds that may contain alkyl, alkenyl, alkylaryl, amino, hydroxyl, alkoxy, halo substituents, and / or heteroatoms such as, but not limited to, nitrogen and oxygen.

[0015] As used herein, molecular weight is measured by gel permeation chromatography (GPC) using commercially available polystyrene standards (having Mn of about 180 to about 18,000 as calibration standards). The molecular weight (Mn) of any embodiment herein may be determined using a gel permeation chromatography (GPC) instrument from Waters or similar instrumentation, and data processed with Waters Empower Software or similar software. The GPC instrument may be equipped with a Waters Separation Module and a Waters Refractive Index Detector (or similar optional instrumentation). GPC operating conditions may include a guard column, four Agilent PLgel columns (300 x 7.5 mm long, 5 μm particle size, and pore size range 100-10,000 Å), and a column temperature of about 40°C. Unstabilized HPLC-grade tetrahydrofuran (THF) may be used as the solvent at a flow rate of 1.0 mL / min. GPC instruments can be calibrated with commercially available polystyrene (PS) standards with narrow molecular weight distributions ranging from 500 to 380,000 g / mol. Calibration curves can be extrapolated for samples with masses less than 500 g / mol. Samples and PS standards can be dissolved in THF, prepared at concentrations of 0.1 to 0.5 wt.%, and used without filtration. GPC measurements are also described in U.S. Pat. No. 5,266,223, incorporated herein by reference. The GPC method also provides molecular weight distribution information. See, for example, W.W. Yau, J.J. Kirkland, and D.D. Bly, "Modern Size Exclusion Liquid Chromatography," John Wiley and Sons, New York, 1979, incorporated herein by reference.

[0016] Throughout this disclosure, the terms "comprises," "includes," "contains," and the like are intended to be open-ended and should be understood to include any element, step, or ingredient not expressly recited. The phrase "consisting essentially of" means including any explicitly recited element, step, or ingredient, as well as any additional elements, steps, or ingredients that do not materially affect the basic and novel aspects of the invention. This disclosure also contemplates that any composition described using the terms "comprises," "includes," or "contains" should be interpreted as including a disclosure of the same composition "consisting essentially of" or "consisting of" the specifically recited ingredient. [Brief explanation of the drawings]

[0017] [Figure 1] 31P NMR spectra of comparative and inventive hydraulic fluids containing the alkylated diisopropyldithiophosphate antiwear additive of the present disclosure; [Figure 2] 1 is a plot of copper corrosion for two different treat rates of alkylated diisopropyldithiophosphate antiwear additives in comparative and inventive hydraulic fluids; [Figure 3] 1 is a plot of copper corrosion for two different treat rates of alkylated diisopropyldithiophosphate antiwear additives in comparative and inventive hydraulic fluids; [Figure 4] 1 is an image showing a comparative example reaction product of an organic hydroxy compound with phosphorus pentasulfide; [Figure 5] 1 is an image showing a condensate obtained by distillation of the reaction product of an organic hydroxy compound and phosphorus pentasulfide. DETAILED DESCRIPTION OF THE INVENTION

[0018] Disclosed herein are improved ashless antiwear additives and lubricating compositions containing such improved ashless antiwear additives that provide good antiwear performance while improving copper corrosion. In one embodiment, the ashless antiwear additive is an oil-soluble phosphorus antiwear additive. In one approach, the lubricating compositions herein contain at least one or more base oils of lubricating viscosity and the novel ashless dithiophosphate ester antiwear additive. In one aspect, the oil-soluble phosphorus antiwear additive herein is prepared by (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; (b) evaporating and / or distilling the reaction product and recovering a condensate therefrom to provide a distilled reaction product comprising a diester of a dithiophosphate; and (c) reacting the condensate with an organic compound, such as an unsaturated ester of a carboxylic acid, to form the improved oil-soluble phosphorus antiwear additive. The improved oil-soluble phosphorus antiwear additives of the present disclosure exhibit good antiwear performance (measured by the 4-ball test according to ASTM D4172 at 1200 rpm, 40 kg, 75°C, 1 hour) while also exhibiting good copper corrosion performance (measured according to ASTM D4951).

[0019] As described in more detail below, the improved performance of oil-soluble phosphorus antiwear additives and lubricating compositions containing such antiwear additives is, in some embodiments, the result of evaporating and / or distilling the reaction product of an organic hydroxy compound and phosphorus pentasulfide and recovering a condensate from the distillation. In some approaches or embodiments, the condensate from the evaporation and / or distillation comprises an isolated and / or improved dithiophosphoric acid intermediate (i.e., a distilled diester of a dithiophosphoric acid) for reaction with a wide variety of organic compounds, such as unsaturated esters of carboxylic acids, as discussed further below, to form the improved oil-soluble phosphorus antiwear additives of the present disclosure.

[0020] The oil-soluble phosphorus anti-wear additives herein can be prepared in many ways, but are preferably prepared by first reacting an organic hydroxy compound, such as an alcohol or phenol, with phosphorus pentasulfide (optionally in the presence of caprolactam). In some approaches, the phosphorus pentasulfide may be its monomer or dimer. Suitable organic hydroxy compounds may include normal straight-chain alcohols, branched-chain alcohols, hydroxyaryl compounds such as phenols and naphthols, substituted arylhydroxy compounds such as diamylphenols, or any other hydroxyorganic material whose hydroxy groups react with phosphorus pentasulfide. In one approach, the starting alcohol is a saturated alcohol or a substituted arylhydroxy compound, such as an arylhydroxy compound substituted with a saturated alkyl group. In some approaches, the organic hydroxy compound may be one or more C1-C10 (in other approaches, C1-C6) straight-chain or branched alcohols, hydroxyaryl compounds, or mixtures thereof, such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, phenol, naphthol, amyl alcohol, hexyl alcohol, isohexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol, octadecyl alcohol, 2-ethylhexyl alcohol, 4-methyl-2-pentyl alcohol, phenyl alcohol, butylphenyl alcohol, cyclohexyl alcohol, methylcyclopentyl alcohol, propenyl alcohol, butenyl alcohol, or combinations thereof. Preferred organic hydroxy compounds herein include C1-C4 alcohols, such as ethyl alcohol, propyl alcohol, or isopropyl alcohol; most preferably, the organic hydroxy compound is isopropyl alcohol.

[0021] The resulting reaction product of the organic hydroxy compound and phosphorus pentasulfide may contain various residual side reactants, including polysulfides such as polysulfides of diesters of dithiophosphoric acids. An exemplary reaction scheme for the first reaction step is shown in Scheme I below (R1 is a C1-C10 linear or branched alcohol, a hydroxyaryl compound, or other alcohol as defined above, preferably isopropyl alcohol or an isopropyl group), to form a reaction product containing one or more diesters of dithiophosphoric acids and various phosphorus polysulfide side reactants, including at least the exemplary diisopropyl dithiophosphoric acid phosphorus polysulfide species shown below, where x is an integer from 1 to 6 (in some procedures, 1 to 3, or 1 to 5, or 2 to 5, or 3 to 5, or 4 to 5).

[0022] [ka]

[0023] Prior to further reaction, the above reaction product, containing at least the dithiophosphoric acid diester and various residual phosphorus polysulfides, is further processed using evaporation or distillation techniques to isolate the desired dithiophosphoric acid diester from the undesired phosphorus polysulfides in the reaction product. Any number of evaporation and / or distillation techniques may be used to achieve this separation and isolation of the desired dithiophosphoric acid diester. For example, suitable evaporation and / or distillation may be carried out using a falling film evaporator, thin film evaporator, centrifugal thin film evaporator, short-path evaporation / distillation, spinning cone evaporator, evaporative scraped surface heat exchanger, rising film evaporator, centrifugal distillation, and the like, or combinations thereof, as needed for the particular application. One or more of each unit operation may be used in parallel or series as needed for the particular application.

[0024] In one approach, a suitable evaporator typically includes a cylindrical, heated body and a rotor. Typically, the intermediate reaction mixture described above enters the heated body at the top and is uniformly distributed over the heated inner surface by the rotor. Volatile components rapidly evaporate (in this case, the desired dithiophosphate diester is distilled), while nonvolatile components (in this case, the undesired polysulfide residual product) are discharged through a bottom outlet. More specifically, a suitable evaporator may include an upright cylindrical vessel with a vertical rotor shaft extending concentrically within the vessel. The inlet supplies the material to be evaporated to a distributor mechanism that spreads the material in a thin film around the vessel's inner wall, and may include one or more wiper assemblies connected to the rotor shaft below the distributor that operate to form a thin film of liquid on the inner wall. Heating of the inner wall then evaporates the liquid film. An internal condenser, often located in the center of the cylindrical vessel, may be used to condense the distillate phase, which is then collected in a suitable tank. The nonvolatile bottoms containing the undesired polysulfide components are collected in a separate tank and thereby separated from the upper volatile materials containing the desired dithiophosphate diesters which are condensed into the distillate.

[0025] Separation techniques include selected pressure and temperature combinations in an evaporator or distillation to isolate and separate the desired product. In some embodiments, distillation of the reaction product containing the dithiophosphate diester and phosphorus polysulfide mixture described above may be carried out preferably in a thin-film evaporator or short-path evaporator. Suitable distillation conditions may include a temperature of at least about 50°C, or at least about 80°C (preferably about 90°C to about 120°C, more preferably about 90°C to about 105°C), combined with a suitable pressure of at least about 0.1 Torr, or about 0.3 Torr to about 1.0 Torr, or about 0.4 Torr to about 1 Torr (preferably about 0.4 Torr to about 0.6 Torr, more preferably about 0.45 Torr to about 0.55 Torr). Condensate may be recovered from the distillation at a temperature of about 10°C or below (preferably about 2°C to about 8°C, more preferably about 4°C to about 6°C). In one approach, the distillation may involve a distillate (recovered as condensate) to bottoms or residue split ratio of about 90-98% distillate to about 2 to about 10% residue or bottoms. In one approach using a thin film evaporator or centrifugal thin film evaporator, the residence time of the components of the composition in the heated device is short because the thin film allows for relatively rapid distillation and / or evaporation.

[0026] The condensate from the distillation contains the desired dithiophosphate diester (e.g., dialkyldithiophosphate) substantially free of phosphorus polysulfides from the reaction product. In one approach, the dialkyldithiophosphate in the condensate may include one or more of dipropyldithiophosphate, diisopropyldithiophosphate, dibutyldithiophosphate, diisobutyldithiophosphate, or a combination thereof, preferably diisobutyldithiophosphate. Without wishing to be limited by theory, it is believed that the condensate is substantially free of phosphorus polysulfides from the above-described reaction product, and such content may contain less than about 1 wt. %, less than about 0.5 wt. %, or less than about 0.25 wt. % of any phosphorus polysulfide, e.g., phosphorus polysulfide of the dithiophosphate diester.

[0027] The condensate from evaporation or distillation, containing the distilled dithiophosphate diester, is then further reacted in a second step with another organic compound, preferably an unsaturated ester of a carboxylic acid, to form the oil-soluble phosphorus antiwear additive of the present disclosure. While a wide variety of unsaturated organic compounds may be used in this further reaction, including those containing other functional groups in addition to multiple bonds, preferred further reactions in this second step include unsaturated esters of carboxylic acids, as discussed further below. For example, unsaturated fatty acid esters, alkyl (meth)acrylates, wax olefins, oleic acid and its esters and / or salts thereof, various unsaturated hydrocarbons derived from linseed oil, soybean oil, paraffin wax, unsaturated alcohols, and / or other natural or synthetic oils may be further reacted with the condensate obtained from distillation. However, preferred organic compounds in this second reaction step include unsaturated esters of carboxylic acids, which may include C1-C20 alkyl (meth)acrylates, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, or combinations thereof. As used herein and as understood by those skilled in the art, (meth)acrylate includes both methacrylate and / or acrylate. This second-step reaction may be carried out at about 70°C to about 150°C for about 2 to about 4 hours, or as needed to obtain the desired end product. In some embodiments, the resulting oil-soluble phosphorus anti-wear additive herein may comprise an alkylated dithiophosphate ashless thiophosphate anti-wear additive, such as ethyl 3-((diisobutoxyphosphorothioyl)thio)propanoate, methyl 4-((diisobutoxyphosphorothioyl)thio)butanoate, and / or ethyl 3-((diisopropoxyphosphorothioyl)thio)butanoate, or combinations thereof and the like. An exemplary Reaction Scheme II for the second reaction step of the condensate is shown below, using ethyl acrylate as the unsaturated carboxylic acid ester, with R1 (preferably an isopropyl group) as defined above (other esters described herein may be used as well).

[0028] [ka]

[0029] In one approach or embodiment, the oil-soluble phosphorus antiwear additive herein may be prepared by reacting, in a first reaction step, the above-described organic hydroxy compound (preferably isopropyl alcohol) and phosphorus pentasulfide in a molar ratio of organic hydroxy compound to phosphorus pentasulfide of about 4:1 to about 10:1 to form the above-described reaction product. The reaction product is then distilled, and a condensate, preferably substantially free of phosphorus polysulfide, is recovered from the distillate containing the dialkyldithiophosphoric acid. This condensate is then further reacted in a second reaction step with the above-described unsaturated ester of carboxylic acid (preferably ethyl acrylate), wherein the molar ratio of the unsaturated ester of carboxylic acid to the organic hydroxy compound is about 0.1:1 to about 0.5:1. The resulting oil-soluble phosphorus antiwear additive may be used in lubricating compositions in an amount of preferably about 0.1 to about 5 wt. %, in another approach about 0.1 to about 2.0 wt. %, and in a further approach about 0.2 to about 0.5 wt. %.

[0030] base oil In one approach, base oils suitable for use in the lubricating compositions herein with the novel ashless antiwear additive include mineral oils, synthetic oils, and all common lubricating base oils. Mineral oils can be naphthenic or paraffinic. Mineral oils can be refined by conventional methods using acids, alkalis, and other agents such as clay or aluminum chloride, or can be extracted oils produced by solvent extraction using solvents such as phenol, sulfur dioxide, furfural, or dichlorodiethyl ether. Mineral oils can be hydrotreated or hydrofinished, dewaxed by a cooling or catalytic dewaxing process, or hydrocracked (such as the Yubase® family of hydrocracked base oils manufactured by SK Innovation Co., Ltd. (Seoul, Korea)). Mineral oils can be produced from natural crude oil sources or can be composed of isomerized wax materials or residues from other refining processes.

[0031] The base oil or base oils of lubricating viscosity used in the compositions herein may be selected from the base oils of Groups I to V as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. These three base oil groups are as follows:

[0032] [Table 1]

[0033] Groups I, II, and III are mineral oil process stocks and may be preferred for the fluids of this application. It should be noted that although Group III base oils are derived from mineral oils, the rigorous processing these fluids undergo results in their physical properties being very similar to some true synthetic oils, such as PAOs. Therefore, oils derived from Group III base oils may be referred to in the industry as synthetic fluids. Suitable oils may be derived from hydrocracked, hydrogenated, hydrofinished, unrefined, refined, and rerefined oils, as well as mixtures thereof. In some approaches, the base oil may be a blend of Group I, Group II, and / or Group III oils, and the blend may be from about 0% to about 100% Group I oil, from about 0% to about 100% Group II oil, from about 0% to about 100% Group III oil, or various blends of Group I and II, Group I and III, or Group II and III oil blends.

[0034] Unrefined oils are derived from natural, mineral, or synthetic sources with little or no further purification processing. Refined oils are similar to unrefined oils except that they have been treated with one or more purification steps, which may result in the improvement of one or more properties. Examples of suitable purification techniques include solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Oils refined to edible quality may or may not be useful. Edible oils may also be called white oils. In some embodiments, the lubricating oil composition does not include edible oils or white oils.

[0035] Re-refined oils are also known as reclaimed or reprocessed oils. These oils are obtained using the same or similar processes as refined oils. Often, these oils are further processed by techniques directed to the removal of spent additives and oil breakdown products.

[0036] Mineral oils may include oils obtained by drilling, or from plants and animals, or any mixture thereof. For example, such oils may include, but are not limited to, castor oil, lard oil, olive oil, peanut oil, corn oil, soybean oil, and linseed oil, as well as mineral lubricating oils, such as liquid petroleum oils and solvent- or acid-treated mineral lubricating oils of the paraffinic, naphthenic, or mixed paraffin-naphthenic types. Such oils may be partially or fully hydrogenated, if desired. Oils derived from coal or shale may also be useful.

[0037] The major amount of base oil included in the fluids herein may be selected from the group consisting of Group I, Group II, Group III, and combinations of two or more of the foregoing, where the major amount of base oil is other than the base oil resulting from the provision of additive components or viscosity index improvers in the composition. In another embodiment, the major amount of base oil included in the lubricating composition may be selected from the group consisting of Group I, Group II, and combinations of two or more of the foregoing, where the major amount of base oil is other than the base oil resulting from the provision of additive components or viscosity index improvers in the composition.

[0038] The base oil may also be any synthetic base oil from API Group IV or V, and / or a combination of synthetic and mineral base oils. Useful synthetic lubricating oils may include hydrocarbon oils such as polymerized, oligomerized, or interpolymerized olefins (e.g., polybutylene, polypropylene, propylene-isobutylene copolymers); poly(1-hexene), poly(1-octene), trimers or oligomers of 1-decene, such as poly(1-decene) (such materials are often referred to as α-olefins), and mixtures thereof; alkyl-benzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di-(2-ethylhexyl)-benzene); polyphenyls (e.g., biphenyl, terphenyl, alkylated polyphenyls); diphenylalkanes, alkylated diphenylalkanes, alkylated diphenyl ethers, and alkylated diphenyl sulfides, as well as their derivatives, analogs, and homologs, or mixtures thereof. Polyalphaolefins are typically hydrogenated materials.

[0039] Other synthetic lubricating oils include polyol esters, diesters, liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, and diethyl ester of decane phosphonic acid), or polymeric tetrahydrofurans. Synthetic oils can be produced by the Fischer-Tropsch reaction and are typically hydroisomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, the oils can be prepared by the Fischer-Tropsch gas-to-liquid synthesis procedure, as well as other gas-to-liquid oils.

[0040] The amount of base oil of lubricating viscosity in the compositions herein can be the remainder remaining after subtracting the total amount of performance additives from 100% by weight. For example, the oil of lubricating viscosity can be present in the final fluid in a "major amount," such as greater than about 50%, greater than about 60%, greater than about 70%, greater than about 80%, greater than about 85%, greater than about 90%, or greater than 95% by weight.

[0041] In some approaches, preferred base oils or base oils of lubricating viscosity have less than about 25 ppm sulfur, a viscosity index greater than about 120, and a kinematic viscosity at about 100°C of about 2 to about 8 cSt. In other approaches, base oils of lubricating viscosity have less than about 25 ppm sulfur, a viscosity index greater than 120, and a kinematic viscosity at 100°C of about 4 cSt. The base oils may have a CP (paraffinic carbon content) of greater than 40%, greater than 45%, greater than 50%, greater than 55%, or greater than 90%. The base oils may have a CA (aromatic carbon content) of less than 5%, less than 3%, or less than 1%. The base oils may have a CN (naphthenic carbon content) of less than 60%, less than 55%, less than 50%, or less than 50%, and greater than 30%. The base oils may have a ratio of 1-ring naphthenes to 2-ring naphthenes to 6-ring naphthenes of less than 2, less than 1.5, or less than 1.

[0042] Suitable lubricant compositions herein may contain additive components in the ranges listed in Table 2 below.

[0043] [Table 2]

[0044] The percentages of each component above represent the weight percent of each component, based on the total weight of the final additive or lubricating oil composition. The remainder of the lubricating oil composition consists of one or more base oils or solvents. The additives used in formulating the compositions described herein can be blended into the base oil or solvent individually or in various subcombinations. However, it may be preferred to blend all of the components simultaneously using an additive concentrate (i.e., additives plus a diluent such as a hydrocarbon solvent).

[0045] Lubricating compositions described herein containing the improved ashless dithiophosphate antiwear reaction products of the present disclosure exhibit good antiwear performance (measured by a four-ball test according to ASTM D4172 at 1200 rpm, 40 kg, and 75°C for 1 hour) while also exhibiting good copper corrosion performance (measured according to ASTM D130 and ASTM D4951). For example, the lubricating compositions may exhibit a wear scar of about 0.350 to about 0.460 mm (preferably, about 0.350 mm to about 0.410 mm, or more preferably, about 0.350 mm to about 0.370 mm). At the same time, the lubricating compositions may exhibit copper corrosion of 150 ppm or less copper, more preferably 80 ppm or less copper, and even more preferably 5 ppm or less copper, as measured by ASTM D130 and D4951 according to the examples.

[0046] In one approach, the lubricating compositions herein are suitable for hydraulic fluids or driveline lubricating compositions and may be used to lubricate mechanical parts such as gears, transmissions, or gearbox components. The lubricating fluids according to the present disclosure can be used in gear applications such as industrial gear applications, automotive gear applications, axles, and fixed gearboxes. Gear types may include, but are not limited to, spur, spiral, worm, rack and pinion, involute, bevel, helical, planetary, and hypoid gears, as well as limited slip applications and differentials. The driveline lubricating compositions disclosed herein are also suitable for automatic or manual transmissions, including step automatic transmissions, continuously variable transmissions, semi-automatic transmissions, automated manual transmissions, toroidal transmissions, and dual-clutch transmissions.

[0047] Optional Additives In other words, the lubricating compositions herein containing such additives as described above may also contain one or more optional components, provided that the amounts thereof do not affect the performance characteristics described in the preceding paragraphs. These optional components are described in the following paragraphs.

[0048] Other phosphorus-containing compounds The lubricant compositions herein may contain one or more phosphorus-containing compounds, which may impart antiwear benefits to the fluid. The one or more phosphorus-containing compounds may be present in the lubricant composition in an amount ranging from about 0 wt. % to about 15 wt. %, or from about 0.01 wt. % to about 10 wt. %, or from about 0.05 wt. % to about 5 wt. %, or from about 0.1 wt. % to about 3 wt. % of the lubricant composition. The phosphorus-containing compounds may provide the lubricant composition with up to 5000 ppm phosphorus, or from about 50 to about 5000 ppm phosphorus, or from about 300 to about 1500 ppm phosphorus, or up to 600 ppm phosphorus, or up to 900 ppm phosphorus.

[0049] The one or more phosphorus-containing compounds may comprise ashless phosphorus-containing compounds.Suitable examples of phosphorus-containing compounds include, but are not limited to, thiophosphates, dithiophosphates, phosphates, phosphoric acid esters, phosphate esters, phosphites, phosphonates, phosphorus-containing carboxylic acid esters, ethers, or amide salts thereof, and mixtures thereof.Phosphorus-containing antiwear agents are more fully described in EP 0612839.

[0050] It should be noted that the terms phosphonate and phosphite are often used interchangeably in the lubricant industry. For example, dibutyl hydrogen phosphonate is sometimes referred to as dibutyl hydrogen phosphite. It is within the scope of the present invention that the lubricant compositions of the present invention include phosphorus-containing compounds that may be referred to as either phosphites or phosphonates.

[0051] In any of the above phosphorus-containing compounds, the compound can have from about 5% to about 20% by weight phosphorus, or from about 5% to about 15% by weight phosphorus, or from about 8% to about 16% by weight phosphorus, or from about 6% to about 9% by weight phosphorus.

[0052] In some embodiments, the ashless phosphorus-containing compound can be a dialkyldithiophosphate ester, amyl acid phosphate, diamyl acid phosphate, dibutyl hydrogen phosphate, dimethyloctadecyl phosphate, salts thereof, and mixtures thereof.

[0053] The ashless phosphorus-containing compound has the formula:

[0054] [ka] and wherein R1 is S or O, R2 is -OR", -OH, or -R", R3 is -OR", -OH, or SR'"C(O)OH, R4 is -OR", R'" is a C1-C3 branched or straight chain alkyl chain, and R" is a C1-C18 hydrocarbyl chain. When the phosphorus-containing compound has the structure shown in Formula XIV, the compound can have from about 8% to about 16% by weight of phosphorus.

[0055] In some embodiments, the lubricant composition comprises a phosphorus-containing compound of Formula XIV, where R1 is S, R2 is —OR″, R3 is SR′″COOH, R4 is —OR″, R′″ is a C3 branched alkyl chain, and R″ is C4, and the phosphorus-containing compound is present in an amount providing 80 to 900 ppm of phosphorus to the lubricant composition.

[0056] In another embodiment, the lubricant composition comprises a phosphorus-containing compound of Formula XIV, where R1 is O, R2 is —OH, R3 is —OR″ or —OH, R4 is —OR″, and R″ is C5, and the phosphorus-containing compound is present in an amount providing 80 to 1500 ppm of phosphorus to the lubricant composition.

[0057] In yet another embodiment, the lubricant composition includes phosphorus-containing compounds of Formula XIV, where R1 is O, R2 is OR″, R3 is H, R4 is —OR″, and R″ is C4, and the one or more phosphorus-containing compounds are present in an amount providing 80 to 1550 ppm of phosphorus to the lubricant composition.

[0058] In another embodiment, the lubricant composition comprises a phosphorus-containing compound of Formula XIV, where R1 is O, R2 is —R″, R3 is —OCH3 or —OH, R4 is —OCH3, and R″ is C18, and the one or more phosphorus-containing compounds are present in an amount providing 80 to 850 ppm of phosphorus to the lubricant composition.

[0059] In some embodiments, the phosphorus-containing compound has the structure shown in Formula XIV and provides from about 80 to about 4500 ppm of phosphorus to the lubricant composition. In other embodiments, the phosphorus-containing compound is present in an amount to provide from about 150 to about 1500 ppm of phosphorus, or from about 300 to about 900 ppm of phosphorus, or from about 800 to 1600 ppm of phosphorus, or from about 900 to about 1800 ppm of phosphorus to the lubricant composition.

[0060] Other anti-wear agents The lubricant composition may also contain other antiwear agents that are phosphorus-free compounds. Examples of such antiwear agents include boric acid esters, boric acid epoxides, thiocarbamate compounds (e.g., thiocarbamate esters, alkylene-bonded thiocarbamates, and bis(S-alkyldithiocarbamyl)disulfides, thiocarbamate amides, thiocarbamic acid ethers, alkylene-bonded thiocarbamates, and bis(S-alkyldithiocarbamyl)disulfides, and mixtures thereof), sulfurized olefins, tridecyl adipate, titanium compounds, and long-chain derivatives of hydroxylcarboxylic acids, such as tartrate derivatives, tartramide, tartrimide, citrate, and mixtures thereof. A suitable thiocarbamate compound is molybdenum dithiocarbamate. A suitable tartrate derivative or tartrimide may contain an alkyl-ester group, where the total number of carbon atoms on the alkyl group may be at least 8. The tartrate derivatives or tartrimides may contain alkyl-ester groups, where the total number of carbon atoms on the alkyl group may be at least 8. The antiwear agent may, in one embodiment, include citrate. The additional antiwear agent may be present in a range including from about 0 wt. % to about 15 wt. %, or from about 0.01 wt. % to about 10 wt. %, or from about 0.05 wt. % to about 5 wt. %, or from about 0.1 wt. % to about 3 wt. % of the lubricating oil composition.

[0061] Other extreme pressure agents The lubricant compositions of this disclosure may also contain other extreme pressure agents. The extreme pressure agents may contain sulfur and may contain at least 12 wt. % sulfur. In some embodiments, the extreme pressure agents added to the lubricating oil are sufficient to provide the lubricant composition with at least 350 ppm sulfur, 500 ppm sulfur, 760 ppm sulfur, about 350 to about 2,000 ppm sulfur, about 2,000 to about 30,000 ppm sulfur, about 2,000 to about 4,800 ppm sulfur, or about 4,000 to about 25,000 ppm sulfur.

[0062] A wide variety of sulfur-containing extreme pressure agents are suitable, including sulfurized animal or vegetable fats or oils, sulfurized animal or vegetable fatty acid esters, fully or partially esterified esters of trivalent or pentavalent acids of phosphorus, sulfurized olefins (e.g., U.S. Pat. Nos. 2,995,569, 3,673,090, 3,703,504, 3,703,505, 3,796,661, 3,873,454, 4,119,549, 4,119,550, 4,147,640, 4,191,659, 4,240,958, 4,344,854, 4,472,306, and 4, 711,736), dihydrocarbyl polysulfides (see, e.g., U.S. Pat. Nos. 2,237,625, 2,237,627, 2,527,948, 2,695,316, 3,022,351, 3,308,166, 3,392,201, 4,564,709, and British Patent No. 1,162,334), functionally substituted dihydrocarbyl polysulfides (see, e.g., U.S. Pat. No. 4,218,332), and polysulfide olefin products (see, e.g., U.S. Pat. No. 4,795,576). Other suitable examples include sulfurized olefins, sulfur-containing aminoheterocyclic compounds, 5-dimercapto-1,3,4-thiadiazoles, polysulfides having a majority of S3 and S4 sulfides, sulfurized fatty acids, sulfurized branched-chain olefins, organic polysulfides, and mixtures thereof.

[0063] In some embodiments, the extreme pressure agent is present in the lubricating composition in an amount up to about 3.0 wt % or up to about 5.0 wt %. In other embodiments, the extreme pressure agent is present in an amount from about 0.05 wt % to about 0.5 wt %, based on the total weight of the lubricant composition. In other embodiments, the extreme pressure agent is present in an amount from about 0.1 wt % to about 3.0 wt %, based on the total weight of the lubricant composition. In other embodiments, the extreme pressure agent is present in an amount from about 0.6 wt % to about 1 wt %, based on the total weight of the lubricant composition. In yet other embodiments, the detergent is present in an amount of about 1.0 wt %, based on the total weight of the lubricant composition.

[0064] One suitable class of extreme pressure agents are polysulfides composed of one or more compounds represented by the formula: Ra-Sx-Rb, where Ra and Rb are hydrocarbyl groups, each of which may contain 1 to 18, or in other approaches, 3 to 18, carbon atoms; x may range from 2 to 8, typically from 2 to 5, and particularly 3. In some approaches, x is an integer from 3 to 5, with about 30 to about 60 percent of the x's being the integer 3 or 4. The hydrocarbyl groups may be of a wide variety of types, such as alkyl, cycloalkyl, alkenyl, aryl, or aralkyl. Tertiary alkyl polysulfides, such as di-tert-butyl trisulfide, and mixtures containing di-tert-butyl trisulfide (e.g., mixtures composed primarily or entirely of tri-, tetra-, and pentasulfides) may be used. Examples of other useful dihydrocarbyl polysulfides include diamyl polysulfide, dinonyl polysulfide, didodecyl polysulfide, and dibenzyl polysulfide.

[0065] Another suitable class of extreme pressure agents is sulfurized isobutene, which is made by reacting an olefin, such as isobutene, with sulfur. Sulfurized isobutene (SIB), particularly sulfurized polyisobutylene, typically has a sulfur content of about 10 to about 55% by weight, desirably about 30 to about 50% by weight. A wide variety of other olefins or unsaturated hydrocarbons, such as isobutene dimer or trimer, can be used to form sulfurized olefin extreme pressure agents. Various methods for preparing sulfurized olefins have been disclosed in the prior art. See, for example, U.S. Pat. No. 3,471,404 to Myers, U.S. Pat. No. 4,204,969 to Papay et al., U.S. Pat. No. 4,954,274 to Zaweski et al., U.S. Pat. No. 4,966,720 to DeGonia et al., and U.S. Pat. No. 3,703,504 to Horodysky et al., each of which is incorporated herein by reference.

[0066] Methods for preparing sulfurized olefins, including those disclosed in the aforementioned patents, involve the formation of a material typically referred to as an "adduct," in which an olefin is reacted with a sulfur halide, such as sulfur monochloride. The adduct is then reacted with a sulfur source to provide the sulfurized olefin. The quality of the sulfurized olefin is generally measured by various physical properties, such as viscosity, sulfur content, halogen content, and copper corrosion test weight loss. U.S. Pat. No. 4,966,720 relates to sulfurized olefins useful as extreme pressure additives in lubricating oils and a two-step reaction for their preparation.

[0067] antioxidants The lubricating oil compositions herein may also optionally contain one or more antioxidants. Antioxidant compounds are known and include, for example, phenates, phenate sulfides, sulfurized olefins, phosphosulfurized terpenes, sulfurized esters, aromatic amines, alkylated diphenylamines (e.g., nonyldiphenylamine, di-nonyldiphenylamine, octyldiphenylamine, di-octyldiphenylamine), phenyl-alpha-naphthylamines, alkylated phenyl-alpha-naphthylamines, hindered non-aromatic amines, phenols, hindered phenols, oil-soluble molybdenum compounds, polymeric antioxidants, or mixtures thereof. The antioxidant compounds may be used alone or in combination.

[0068] The hindered phenol antioxidant may contain a secondary butyl group and / or a tertiary butyl group as a steric hindering group. The phenol group may be further substituted with a hydrocarbyl group and / or a bridging group connecting to a second aromatic group. Examples of suitable hindered phenol antioxidants include 2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol, 4-butyl-2,6-di-tert-butylphenol, or 4-dodecyl-2,6-di-tert-butylphenol. In one embodiment, the hindered phenol antioxidant can be an ester and can include, for example, Irganox® L-135 available from BASF or an addition product derived from 2,6-di-tert-butylphenol and an alkyl acrylate, where the alkyl group can contain from about 1 to about 18, or from about 2 to about 12, or from about 2 to about 8, or from about 2 to about 6, or about 4 carbon atoms. Another commercially available hindered phenol antioxidant can be an ester and can include Ethanox® 4716 available from Albemarle Corporation.

[0069] Useful antioxidants may include diarylamines and phenols. In one embodiment, the lubricating oil composition may contain a mixture of diarylamines and phenols, with each antioxidant present in an amount sufficient to provide up to about 5 wt. % antioxidant, based on the weight of the lubricant composition. In one embodiment, the antioxidant may be a mixture of about 0.3 to about 1.5 wt. % diarylamines and about 0.4 to about 2.5 wt. % phenols, based on the weight of the lubricant composition.

[0070] Examples of suitable olefins that can be sulfurized to form sulfurized olefins include propylene, butylene, isobutylene, polyisobutylene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, nonadecene, eicosene, or mixtures thereof. In one embodiment, hexadecene, heptadecene, octadecene, nonadecene, eicosene, or mixtures thereof, as well as their dimers, trimers, and tetramers, are particularly useful olefins. Alternatively, the olefin can be a Diels-Alder adduct of a diene, such as 1,3-butadiene, and an unsaturated ester, such as butyl acrylate.

[0071] Another class of sulfurized olefins includes sulfurized fatty acids and their esters. The fatty acids are often derived from vegetable or animal oils and typically contain from about 4 to about 22 carbon atoms. Examples of suitable fatty acids and their esters include triglycerides, oleic acid, linoleic acid, palmitoleic acid, or mixtures thereof. Often, the fatty acids are derived from lard oil, tall oil, peanut oil, soybean oil, cottonseed oil, sunflower seed oil, or mixtures thereof. The fatty acids and / or esters may be mixed with an olefin, such as an α-olefin.

[0072] The one or more antioxidants may be present in a range of from about 0% to about 20%, or from about 0.1% to about 10%, or from about 1% to about 5% by weight of the lubricating oil composition.

[0073] Dispersants Dispersants contained in the lubricant composition may include, but are not limited to, an oil-soluble polymeric hydrocarbon backbone having functional groups capable of associating with particles to be dispersed. Typically, dispersants contain amine, alcohol, amide, or ester polar moieties attached to the polymer backbone, often through a bridging group. Dispersants may be selected from Mannich dispersants such as those described in U.S. Pat. Nos. 3,634,515, 3,697,574, and 3,736,357; ashless succinimide dispersants such as those described in U.S. Pat. Nos. 4,234,435 and 4,636,322; amine dispersants such as those described in U.S. Pat. Nos. 3,219,666, 3,565,804, and 5,633,326; Koch dispersants such as those described in U.S. Pat. Nos. 5,936,041, 5,643,859, and 5,627,259; and polyalkylene succinimide dispersants such as those described in U.S. Pat. Nos. 5,851,965, 5,853,434, and 5,792,729.

[0074] In some embodiments, the additional dispersant may be derived from polyalphaolefin (PAO), succinic anhydride, olefin maleic anhydride copolymer. As an example, the additional dispersant may be described as poly-PIBSA. In another embodiment, the additional dispersant may be derived from an anhydride grafted onto an ethylene-propylene copolymer. Another additional dispersant may be a high molecular weight ester or half-ester amide.

[0075] When present, the additional dispersant can be used in an amount sufficient to provide up to about 10% by weight, based on the final weight of the lubricating oil composition. Alternative amounts of dispersant that can be used can be from about 0.1% to about 10% by weight, or from about 0.1% to about 10% by weight, or from about 3% to about 8% by weight, or from about 1% to about 6% by weight, based on the final weight of the lubricating oil composition.

[0076] Viscosity Index Improver The lubricant compositions herein may also optionally contain one or more viscosity index improvers. Suitable viscosity index improvers may include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutene, hydrogenated styrene-isoprene polymers, styrene / maleic acid ester copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkylstyrenes, hydrogenated alkenylaryl conjugated diene copolymers, or mixtures thereof. The viscosity index improver may include star polymers, suitable examples of which are described in U.S. Patent Application Publication No. 2012 / 0101017(A1), which is incorporated herein by reference.

[0077] The lubricating oil compositions herein may also optionally contain one or more dispersant viscosity index improvers in addition to or in place of the viscosity index improver. Suitable viscosity index improvers may include functionalized polyolefins, such as ethylene-propylene copolymers functionalized with the reaction product of an acylating agent (such as maleic anhydride) and an amine, amine-functionalized polymethacrylates, or esterified maleic anhydride-styrene copolymers reacted with amines.

[0078] The total amount of viscosity index improver and / or dispersant viscosity index improver can be from about 0% to about 20%, from about 0.1% to about 15%, from about 0.1% to about 12%, or from about 0.5% to about 10%, from about 3% to about 20%, from about 3% to about 15%, from about 5% to about 15%, or from about 5% to about 10% by weight of the lubricating oil composition.

[0079] In some embodiments, the viscosity index improver is a polyolefin or olefin copolymer having a number average molecular weight of about 10,000 to about 500,000, about 50,000 to about 200,000, or about 50,000 to about 150,000. In some embodiments, the viscosity index improver is a hydrogenated styrene / butadiene copolymer having a number average molecular weight of about 40,000 to about 500,000, about 50,000 to about 200,000, or about 50,000 to about 150,000. In some embodiments, the viscosity index improver is a polymethacrylate having a number average molecular weight of about 10,000 to about 500,000, about 50,000 to about 200,000, or about 50,000 to about 150,000.

[0080] Other optional additives The other additives can be selected to perform one or more functions required of the lubricant composition. Furthermore, one or more of the aforementioned additives may be multifunctional and may provide functions in addition to or other than those described herein. The other additives may be in addition to the additives specified in this disclosure and / or may include one or more of metal deactivators, viscosity index improvers, ashless TBN boosters, antiwear agents, corrosion inhibitors, rust inhibitors, dispersants, dispersant viscosity index improvers, extreme pressure agents, antioxidants, foam suppressants, demulsifiers, emulsifiers, pour point depressants, seal swell agents, and mixtures thereof. Typically, fully formulated lubricating oils contain one or more of these performance additives.

[0081] Suitable metal deactivators may include derivatives of benzotriazole (typically tolyltriazole), dimercaptothiadiazole derivatives, 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole, or 2-alkyldithiobenzothiazole; foam suppressors including copolymers of ethyl acrylate, 2-ethylhexyl acrylate, and optionally vinyl acetate; demulsifiers including trialkyl phosphate, polyethylene glycol, polyethylene oxide, polypropylene oxide, and (ethylene oxide-propylene oxide) polymers; pour point depressants including esters of maleic anhydride-styrene, polymethacrylate, polyacrylate, or polyacrylamide.

[0082] Suitable suds suppressors include silicon-based compounds such as siloxanes.

[0083] Suitable pour point depressants may include polymethyl methacrylate or mixtures thereof. The pour point depressant may be present in an amount sufficient to provide from about 0 wt % to about 1 wt %, from about 0.01 wt % to about 0.5 wt %, or from about 0.02 wt % to about 0.04 wt %, based on the final weight of the lubricating oil composition.

[0084] Suitable rust inhibitors can be a single compound or a mixture of compounds that have the property of inhibiting corrosion of ferrous metal surfaces. Non-limiting examples of rust inhibitors useful herein include oil-soluble high molecular weight organic acids such as 2-ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, and cerotic acid, as well as oil-soluble polycarboxylic acids, including dimer and trimer acids such as those produced from tall oil fatty acid, oleic acid, and linoleic acid. Other suitable corrosion inhibitors include long-chain alpha- and omega-dicarboxylic acids in the molecular weight range of about 600 to about 3000, and alkenyl succinic acids in which the alkenyl group contains about 10 or more carbon atoms, such as tetrapropenyl succinic acid, tetradecenyl succinic acid, and hexadecenyl succinic acid. Another useful type of acidic corrosion inhibitor is the half ester of an alkenyl succinic acid having about 8 to about 24 carbon atoms in the alkenyl group with an alcohol, such as a polyglycol. The corresponding half amides of such alkenyl succinic acids are also useful. Useful rust inhibitors are high molecular weight organic acids. In some embodiments, the engine oil does not contain a rust inhibitor.

[0085] When present, rust inhibitors may be used in any amount sufficient to provide from about 0 wt. % to about 5 wt. %, from about 0.01 wt. % to about 3 wt. %, from about 0.1 wt. % to about 2 wt. %, based on the final weight of the lubricating oil composition.

[0086] The lubricant composition may also include a corrosion inhibitor (it should be noted that some of the other mentioned components may also have copper corrosion inhibiting properties). Suitable copper corrosion inhibitors include ether amines, polyethoxylated compounds such as ethoxylated amines and ethoxylated alcohols, imidazolines, mono- and di-alkyl thiadiazoles, and the like.

[0087] Thiazoles, triazoles, and thiadiazoles may also be used in the lubricant. Examples include benzotriazole, tolyltriazole, octyltriazole, decyltriazole, dodecyltriazole, 2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazole, and 2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazole. In one embodiment, the lubricant composition includes a 1,3,4-thiadiazole, such as 2-hydrocarbyldithio-5-mercapto-1,3,4-dithiadiazole.

[0088] Antifoam agents / surfactants may also be included in the fluids according to the present invention. Various agents are known for such applications. A copolymer of ethyl acrylate and hexyl ethyl acrylate, such as PC-1244 available from Solutia, may be used. In other embodiments, a silicone fluid, such as 4% DCF, may be included. Mixtures of antifoam agents may also be present in the lubricant composition. [Example]

[0089] The following examples illustrate exemplary embodiments of the present disclosure. In these examples, as well as elsewhere in this application, all ratios, parts, and percentages are by weight unless otherwise indicated. It is intended that these examples are presented for illustrative purposes only and are not intended to limit the scope of the invention disclosed herein.

[0090] Comparative Example 1 A comparative alkylated diisopropyldithiophosphoric acid was prepared as follows: Approximately 25.7 pounds of isopropanol was charged to a stainless steel reactor, followed by a slow charge of about 23.3 pounds of phosphorus pentasulfide (PS5 having about 27.7% phosphorus) while stirring vigorously to maintain the temperature in the range of about 30°C to about 60°C. Next, about 28.5 pounds of additional phosphorus pentasulfide was charged to the reactor, followed by the slow addition of about 31.5 pounds of additional isopropanol to maintain the reaction temperature below 70°C. After the second isopropanol charge was completed, the reaction temperature was increased to about 80°C to about 85°C in about 60 minutes to form reaction product A. Reaction product A is represented by the image in Figure 4 and is believed to contain at least the following structure of diisopropyldithiophosphoric acid and diisopropyldithiophosphoric acid phosphorus polysulfide (x is 1 to 6):

[0091] [ka]

[0092] An alkylated diisopropyldithiophosphate antiwear additive was then prepared directly from the above reaction product A (containing both diisopropyldithiophosphate and phosphorus polysulfide) as follows: About 34.6 pounds of reaction product A was charged to a stainless steel reactor and heated to about 55° C. Then, about 16.7 pounds of ethyl acrylate was slowly charged to maintain the reaction temperature below 75° C. After the addition of the ethyl acrylate, the reaction was allowed to proceed at about 85° C. for about 2 hours and then vacuum stripped to produce the comparative alkylated diisopropyldithiophosphate antiwear additive.

[0093] Example 1 Reaction Product A, containing diisopropyldithiophosphoric acid and residual phosphorus polysulfide from Comparative Example 1, was further processed in a thin-film evaporator (ICL-04 Short Path Distillation System, GIG Karasek, Austria) to recover a condensate. The thin-film evaporator was operated at a jacket temperature of about 100°C and a pressure of about 0.5 Torr. The condenser was cooled to about 5°C. The evaporator had a split ratio of about 95% distillate and about 5% bottoms or residue. The condensate was collected as distilled diisopropyldithiophosphoric acid and is represented by the image in Figure 5.

[0094] An alkylated diisopropyl dithiophosphoric acid of the present invention was then prepared from the condensate as follows: About 34.6 pounds of the condensate (i.e., distilled diisopropyl dithiophosphoric acid) was charged to a stainless steel reactor and heated to about 55° C. About 16.7 pounds of ethyl acrylate was then slowly charged to maintain the reaction temperature below 75° C. After the addition of the ethyl acrylate, the reaction was allowed to proceed at about 85° C. for about 2 hours and then vacuum stripped to produce an alkylated diisopropyl dithiophosphoric acid antiwear additive of the present invention, which was believed to be substantially free of any phosphorus polysulfides.

[0095] Example 2 Hydraulic lubricating compositions containing the alkylated diisopropyldithiophosphate reaction products of Comparative Example 1 and Inventive Example 1 were prepared as shown in Table 3 below.

[0096] [Table 3] * The hydraulic additive package included base oil, demulsifier, friction modifier, viscosity modifier, anti-wear agent, detergent, corrosion inhibitor, and antioxidant.

[0097] FIG. 1 shows the phosphorus NMR spectra of the comparative and inventive hydraulic fluids from Table 3 above, showing that the comparative hydraulic fluids have additional peaks identified in the figure that are believed to represent various phosphorus polysulfide compositions not found in the inventive hydraulic fluids.

[0098] The hydraulic fluids in Table 3 were evaluated for copper corrosion over an extended period of two days at 121°C according to a method in accordance with ASTM D130. Three coupon containers per finished fluid were prepared for testing (each container containing approximately 45 grams of finished fluid and copper strip). At each time point in Table 4, a container was withdrawn and the solution collected. Two grams of each solution were then subjected to copper corrosion according to ASTM D4951, with the results shown in Table 4 below.

[0099] [Table 4]

[0100] At each treat rate, the fluid of the present invention showed about a 50 to about 65% improvement in copper corrosion. The graphs in Figures 2 and 3 also show the dramatic improvement in copper corrosion between the comparative example and the fluid of the present invention.

[0101] The comparative and inventive fluids were also evaluated for anti-wear performance according to ASTM D4172 at 1200 rpm, 40 KG weight, 75° C. for 1 hour. The results of the wear scar test are shown in Table 5 below.

[0102] [Table 5]

[0103] As shown in Table 5 above, the hydraulic oils of the present invention exhibited the same or slightly better wear scar performance than the comparative hydraulic oils, and as shown in Table 4 above, copper corrosion was dramatically improved.

[0104] It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless expressly and unambiguously limited to one referent. Thus, for example, reference to an "antioxidant" includes two or more different antioxidants. As used herein, the term "comprises" and grammatical variations thereof are intended to be open-ended, such that the recitation of items in a list does not exclude other similar items that may be substituted for or added to the listed items.

[0105] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing quantities, percentages, or proportions, and other numerical values ​​used in the specification and claims should be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0106] It is understood that each component, compound, substituent, or parameter disclosed herein should be construed as disclosed for use alone or in combination with one or more of any and all other components, compounds, substituents, or parameters disclosed herein.

[0107] It is further understood that each range disclosed herein should be construed as a disclosure of each specific value within the disclosed range having the same number of significant digits. Thus, for example, a range of 1 to 4 should be construed as an explicit disclosure of not only the values ​​1, 2, 3, and 4, but also any range of such values.

[0108] It should be further understood that each lower limit of each range disclosed herein should be interpreted as being disclosed in combination with each upper limit of each range and each specific value within each range for the same component, compound, substituent, or parameter. Thus, the present disclosure should be interpreted as a disclosure of all ranges derived by combining each lower limit of each range with each upper limit of each range, or each specific value within each range, or by combining each upper limit of each range with each specific value within each range. In other words, it is also further understood that any range between the endpoints within a broad range is also contemplated herein. Thus, a range of 1 to 4 also means ranges of 1 to 3, 1 to 2, 2 to 4, 2 to 3, etc.

[0109] Furthermore, a specific amount / value of a component, compound, substituent, or parameter disclosed in the description or examples should be construed as a disclosure of either a lower or upper limit of a range and, therefore, can be combined with any other lower or upper limit of a range or specific amount / value for the same component, compound, substituent, or parameter disclosed elsewhere in this application to form a range for that component, compound, substituent, or parameter.

[0110] While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents may occur that are not presently anticipated or presently unforeseeable to Applicants or others skilled in the art. Accordingly, the appended claims as filed, and the appended claims as they may be amended, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims

1. 1. A lubricating composition comprising: one or more base oils of lubricating viscosity; and 1. A lubricating composition comprising an oil-soluble phosphorus anti-wear additive produced by a process comprising: (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; (b) distilling the reaction product and recovering a condensate; and (c) reacting the condensate with an unsaturated ester of a carboxylic acid to form the oil-soluble phosphorus anti-wear additive.

2. 10. The lubricating composition of claim 1, wherein the distillation is carried out at one or more of a temperature of at least about 50°C, a pressure of at least about 0.1 Torr, or a combination thereof, and / or the condensate is recovered at a temperature of about 10°C or less, and / or the distillation is carried out in a falling film evaporator, a thin film evaporator, a centrifugal thin film evaporator, a short stroke evaporator, or a combination thereof.

3. 10. The lubricating composition of claim 1, wherein the condensate comprises a dialkyl dithiophosphoric acid, and / or the dialkyl dithiophosphoric acid comprises dipropyl dithiophosphoric acid, diisopropyl dithiophosphoric acid, dibutyl dithiophosphoric acid, diisobutyl dithiophosphoric acid, or a combination thereof.

4. 2. The lubricating composition of claim 1, wherein the unsaturated ester of a carboxylic acid is a C1 to C20 alkyl (meth)acrylate, and / or the unsaturated ester of a carboxylic acid is methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, or a combination thereof.

5. 2. The lubricating composition of claim 1, wherein the organic hydroxy compound is a C1 to C6 straight chain or branched alcohol, a hydroxyl aryl compound, or a mixture thereof; and / or the organic hydroxy compound is methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, phenol, naphthol, amyl alcohol, hexyl alcohol, iso-hexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol, octadecyl alcohol, 2-ethylhexyl alcohol, 4-methyl-2-pentyl alcohol, phenyl alcohol, butylphenyl alcohol, cyclohexyl alcohol, methylcyclopentyl alcohol, propenyl alcohol, butenyl alcohol, or a combination thereof.

6. 2. The lubricating composition of claim 1, wherein the organic hydroxy compound is isopropyl alcohol, the reaction product comprises diisopropyl dithiophosphoric acid and one or more phosphorus polysulfides, the condensate comprises the diisopropyl dithiophosphoric acid and is substantially free of the one or more phosphorus polysulfides, and the condensate is further reacted with ethyl acrylate to form the oil-soluble phosphorus antiwear additive.

7. 2. The lubricating composition of claim 1, wherein the lubricating composition comprises from about 0.1 to about 5 wt. % of the oil-soluble phosphorus antiwear additive and / or the organic hydroxy compound is provided in a molar ratio to the phosphorus pentasulfide of from about 4:1 to about 10:1 and / or the unsaturated ester of a carboxylic acid is provided in a molar ratio to the organic hydroxy compound of from about 0.1:1 to about 0.5:

1.

8. 1. A method for preparing an oil soluble phosphorus antiwear additive, said method comprising: reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; distilling the reaction product and recovering a condensate therefrom; reacting said condensate with an unsaturated ester of a carboxylic acid to form said oil-soluble phosphorus anti-wear additive.

9. 9. The method of claim 8, wherein the distillation is carried out at a temperature of at least about 50° C., and / or the distillation is carried out at a pressure of at least about 0.1 Torr, and / or the condensate is collected at a temperature of about 10° C. or less, and / or the distillation is carried out in a falling film evaporator, a thin film evaporator, a centrifugal thin film evaporator, a short stroke evaporator, or a combination thereof.

10. 9. The method of claim 8, wherein the condensate comprises a dialkyl dithiophosphoric acid, and / or the dialkyl dithiophosphoric acid is dipropyl dithiophosphoric acid, diisopropyl dithiophosphoric acid, dibutyl dithiophosphoric acid, diisobutyl dithiophosphoric acid, or a combination thereof.

11. 9. The method of claim 8, wherein the unsaturated ester of a carboxylic acid is a C1 to C20 alkyl (meth)acrylate, and / or the unsaturated ester of a carboxylic acid is methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, or a combination thereof.

12. 9. The method of claim 8, wherein the organic hydroxy compound is a C1 to C6 straight chain or branched alcohol, a hydroxyaryl compound, or a mixture thereof, and / or the organic hydroxy compound is methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, tert-butyl alcohol, sec-butyl alcohol, phenol, naphthol, amyl alcohol, hexyl alcohol, iso-hexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol, octadecyl alcohol, 2-ethylhexyl alcohol, 4-methyl-2-pentyl alcohol, phenyl alcohol, butylphenyl alcohol, cyclohexyl alcohol, methylcyclopentyl alcohol, propenyl alcohol, butenyl alcohol, or a combination thereof.

13. 9. The method of claim 8, wherein the organic hydroxy compound is isopropyl alcohol, the reaction product comprises diisopropyl dithiophosphoric acid and one or more phosphorus polysulfides, the condensate comprises the diisopropyl dithiophosphoric acid and is substantially free of the one or more phosphorus polysulfides, and the condensate is further reacted with ethyl acrylate to form the oil soluble phosphorus antiwear additive.

14. 9. The method of claim 8, wherein the organic hydroxy compound is provided in a molar ratio of about 4:1 to about 10:1 relative to the phosphorus pentasulfide and / or the unsaturated ester of a carboxylic acid is provided in a molar ratio of about 0.1:1 to about 0.5:1 relative to the organic hydroxy compound.

15. 1. An oil soluble phosphorus antiwear additive produced by a process comprising the steps of: (a) reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; (b) distilling said reaction product and recovering a condensate therefrom; and (c) reacting said condensate with an unsaturated ester of a carboxylic acid to form the oil soluble phosphorus antiwear additive.

Images