Wear-resistant system for improved copper corrosion

Abstract

To provide an oil-soluble phosphorus antiwear additive, and a lubricating composition comprising the oil-soluble phosphorus antiwear additive improved in terms of copper corrosion.SOLUTION: An oil-soluble ashless antiwear additive and a lubricating composition comprising the ashless antiwear additive improved in terms of copper corrosion performance, are obtained by: reacting an organic hydroxy compound with phosphorus pentasulfide to form a reaction product; distilling the reaction product and recovering a condensate; and reacting the condensate with an unsaturated carboxylic acid to form an oil-soluble phosphorus antiwear additive.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to lubricating compositions containing oil-soluble phosphorus antiwear additives and oil-soluble phosphorus antiwear additives having improved copper corrosion resistance.

Background Art

[0002] Lubricating compositions are designed to balance low wear and low friction while simultaneously minimizing other performance drawbacks. For example, zinc dialkyldithiophosphate, commonly known as ZDDP, is a widely used antiwear additive in lubricants such as engine oils, transmission fluids, and / or hydraulic fluids. However, the zinc provided by such additives can be less desirable depending on the application, leading to an increasing use of so-called ashless or metal-free antiwear additives. Ashless (i.e., metal-free) dithiophosphates are one such alternative, but while ashless dithiophosphates have good antiwear and extreme pressure performance, these additives may tend to corrode metals, particularly copper and bronze metals.

Summary of the Invention

[0003] In one approach or embodiment, the present disclosure provides a lubricating composition comprising one or more base oils having a lubricating viscosity and an oil-soluble phosphorus antiwear 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 carboxylic acid to form an oil-soluble phosphorus antiwear additive.

[0004] In another method or embodiment, the lubricating composition described in the previous paragraph may include optional features and / or embodiments in any combination. These optional features or embodiments may include one or more of the following: The distillation is carried out at a temperature of at least about 50 °C, a pressure of at least about 0.1 torr, or one or more combinations thereof, and / or the condensate is recovered at a temperature of about 10 °C or lower, and / or the distillation is carried out in a falling film evaporator, thin film evaporator, centrifugal thin film evaporator, short path evaporator, or a combination thereof, and / or the condensate contains dialkyldithiophosphoric acid, and / or the dialkyldithiophosphoric acid is dipropyldithiophosphoric acid, diisopropyldithiophosphoric acid, dibutyldithiophosphoric acid, diisobutyldithiophosphoric acid, or a combination thereof, and / or the unsaturated carboxylic acid is a C1-C20 fatty acid, and / or the unsaturated fatty acid is acrylic acid, methacrylic acid, 2-ethylacrylic acid, or a combination thereof, and / or the organic hydroxy compound is a C1-C6 linear or branched alcohol, a hydroxylaryl 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, and / or the organic hydroxy compound is isobutyl alcohol, the reaction product contains diisobutyldithiophosphoric acid and one or more phosphorus polysulfides, the condensate contains diisobutyldithiophosphoric acid and substantially does not contain one or more phosphorus polysulfides, the condensate further reacts with methacrylic acid to form an oil-soluble phosphorus antiwear additive, and / or the lubricating composition is about 0.It contains 1 to about 5% by weight of an oil-soluble phosphorus antiwear additive, and / or the organic hydroxy compound is provided in a molar ratio of about 4:1 to about 10:1 with respect to phosphorus pentasulfide, and / or the unsaturated carboxylic acid is provided in a molar ratio of about 0.01:1 to about 0.5:1 with respect to the organic hydroxy compound.

[0005] In yet another approach or embodiment, a method for preparing an oil-soluble phosphorus antiwear additive is provided by the present disclosure. The method includes 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 carboxylic acid to form an oil-soluble phosphorus antiwear additive.

[0006] In other methods or embodiments, the method of the preceding paragraph may include optional features, steps, or embodiments in any combination. These optional features, steps, or embodiments may include one or more of the following.Distillation is carried out at a temperature of at least about 50 °C, and / or distillation is carried out at a pressure of at least about 0.1 torr, and / or the condensate is recovered at a temperature of about 10 °C or lower, and / or distillation is carried out in a falling-film evaporator, thin-film evaporator, centrifugal thin-film evaporator, short-path evaporator, or a combination thereof, and / or the condensate contains dialkyldithiophosphoric acid, and / or the dialkyldithiophosphoric acid is dipropyldithiophosphoric acid, diisopropyldithiophosphoric acid, dibutyldithiophosphoric acid, diisobutyldithiophosphoric acid, or a combination thereof, and / or the unsaturated carboxylic acid is a C1-C20 fatty acid, and / or the fatty acid is acrylic acid, methacrylic acid, 2-ethylacrylic acid, or a combination thereof, and / or the organic hydroxy compound is a C1-C6 straight-chain or branched alcohol, 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, and / or the organic hydroxy compound is isobutyl alcohol, the reaction product contains diisobutyldithiophosphoric acid and one or more polysulfides of phosphorus, the condensate contains diisobutyldithiophosphoric acid and substantially does not contain one or more polysulfides of phosphorus, the condensate further reacts with methacrylic acid to form an oil-soluble phosphorus antiwear additive, and / or the organic hydroxy compound is provided in a molar ratio of about 4:1 to about 10:1 with respect to phosphorus pentasulfide, and / or the unsaturated carboxylic acid is provided in a molar ratio of about 0.01:1 to about 0.5:1 with respect to the organic hydroxy compound.

[0007] In yet another approach or embodiment, an oil-soluble phosphorus antiwear additive is described herein, and the additive is 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 therefrom; and (c) reacting the condensate with an unsaturated carboxylic acid to form the oil-soluble phosphorus antiwear additive. In yet other embodiments, the oil-soluble phosphorus antiwear additive may include any of the features or embodiments described by any of the embodiments of the lubricants or methods herein.

[0008] In yet another approach or embodiment, the use of evaporation or distillation to recover a condensate from the reaction product of an organic hydroxy compound reacted with phosphorus pentasulfide is described herein, and the condensate further reacts with an unsaturated 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 disclosure will be apparent to those skilled in the art in view of the specification and practice of the invention disclosed herein. The following definitions are provided to clarify the meaning of specific 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 final lubricating product comprising a major amount of base oil and a minor amount of an additive composition, as contemplated herein. In one approach, such fluids are used, for example, in transmissions and / or limited-slip differentials, in extreme pressure conditions such as those of transmission and gear drive components having metal-to-metal contact. In another approach, such fluids are for use in lubricating an engine.

[0011] As used herein, the terms "hydrocarbyl substituent" or "hydrocarbyl group" are used in their ordinary meaning well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly bonded to the remainder of the molecule and mainly having hydrocarbon characteristics. Each hydrocarbyl group is independently selected from hydrocarbon substituents, and a substituted hydrocarbon substituent contains one or more of a halo group, a hydroxyl group, an alkoxy group, a mercapto group, a nitro group, a nitroso group, an amino group, a pyridyl group, a furyl group, an imidazolyl group, oxygen, and nitrogen, and two or fewer non-hydrocarbon substituents are present per ten carbon atoms in the hydrocarbyl group.

[0012] As used herein, the terms "percent by weight" or "wt%" mean, unless otherwise indicated, the percentage that the listed component represents relative to the total weight of the composition. All percentages in this specification are by weight unless otherwise specified.

[0013] As used herein, the terms "soluble", "oil-soluble", or "dispersible" may indicate that a compound or additive is soluble, soluble, miscible, or suspendable in oil at all ratios, but not necessarily so. However, the foregoing terms mean that they are soluble, suspendable, soluble, or stably dispersible in oil to such an extent that they exhibit their intended effects in an environment where, for example, oil is used. Further, if desired, incorporating other additives may also make it possible to incorporate higher levels of specific additives.

[0014] As used herein, the term "alkyl" refers to straight-chain, branched-chain, cyclic, and / or substituted saturated chain moieties of from about 1 to about 200 carbon atoms. As used herein, the term "alkenyl" refers to straight-chain, branched-chain, cyclic, and / or substituted saturated chain moieties of from about 3 to about 30 carbon atoms. As used herein, the term "aryl" refers to monocyclic and polycyclic aromatic compounds that may include 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 an Mn of about 180 to about 18,000 as calibration standards. The molecular weight (Mn) of any embodiment herein can be determined using gel permeation chromatography (GPC) equipment obtained from Waters or similar equipment, and data processed with Waters Empower Software or similar software. The GPC equipment can be provided with a Waters separation module and a Waters refractive index detector (or any optional similar equipment). The GPC operating conditions can include a guard column, four Agilent PLgel columns (length 300 × 7.5 mm, particle size 5 μm, and pore size range 100 to 10,000 Å), and a column temperature of about 40°C. Unstabilized HPLC grade tetrahydrofuran (THF) can be used as the solvent at a flow rate of 1.0 mL / min. The GPC equipment can be calibrated with commercially available polystyrene (PS) standards having a narrow molecular weight distribution in the range of 500 to 380,000 g / mol. The calibration curve can be extrapolated for samples having a mass of less than 500 g / mol. The sample and the PS standard can be dissolved in THF and prepared at a concentration of 0.1 to 0.5 wt%, and can be used without filtration. The GPC measurement is also described in U.S. Patent No. 5,266,223, which is incorporated herein by reference. The GPC method further provides molecular weight distribution information. See also, for example, W.W. Yau, J.J. Kirkland and D.D. Bly, "Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New York, 1979, which is incorporated herein by reference.

[0016] Throughout the present disclosure, terms such as "comprises," "includes," "contains," etc. are considered to be open-ended and should be understood to include any element, step, or ingredient not explicitly recited. The phrase "consisting essentially of" means including any explicitly recited element, step, or ingredient, and any additional element, step, or ingredient that does not materially affect the basic and novel aspects of the invention. The present disclosure also contemplates that any composition described using the terms "comprises," "includes," "contains" should be construed as also including a disclosure of the same composition "consisting essentially of" or "consisting of" its specifically recited components.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0018] This specification discloses improved ashless antiwear additives and lubricating compositions containing such improved ashless antiwear additives that provide good antiwear performance along with improved copper corrosion. In one approach or embodiment, the ashless antiwear additive is an oil-soluble phosphorus antiwear additive. In one aspect, the lubricating compositions of this specification include at least one or more base oils having a lubricating viscosity and a novel ashless dithiophosphate antiwear additive. In another aspect, the oil-soluble phosphorus antiwear additives of this specification are 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 containing a dithiophosphate diester, and (c) reacting the condensate with an organic compound such as an unsaturated carboxylic acid to form an improved oil-soluble phosphorus antiwear additive. The improved oil-soluble phosphorus antiwear additives of the present disclosure exhibit good antiwear performance (measured by a four-ball test in accordance with ASTM D4172 at 1200 rpm, 40 kg, 75 °C for 1 hour) and at the same time exhibit good copper corrosion performance (measured in accordance with ASTM D4951).

[0019] As described in more detail below, the improved performance of the 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 the condensate from the distillation. In some approaches or embodiments, the condensate from the evaporation and / or distillation reacts with a variety of organic compounds such as unsaturated carboxylic acids, discussed further below, to form an isolated and / or improved dithiophosphate intermediate (i.e., the distilled diester of dithiophosphoric acid) for forming the improved oil-soluble phosphorus antiwear additives of the present disclosure.

[0020] The oil-soluble phosphorus antiwear additives of this specification can be prepared in many ways, but preferably, they are first prepared by reacting an organic hydroxy compound such as alcohol or phenol with phosphorus pentasulfide (optionally in the presence of caprolactam). In some procedures, the phosphorus pentasulfide may be its monomer or dimer. Suitable organic hydroxy compounds include normal straight-chain alcohols, branched-chain alcohols, hydroxyaryl compounds such as phenol and naphthol, substituted aryl hydroxy compounds such as diamylphenol, or any other hydroxy organic substance whose hydroxy group reacts with phosphorus pentasulfide. In one procedure, the starting alcohol is a substituted aryl hydroxy compound such as a saturated alcohol or an aryl hydroxy compound substituted by a saturated alkyl group. In some procedures, the organic hydroxy compound is one or more of C1-C10 (in other procedures, 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, 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. Preferred organic hydroxy compounds of this specification include C1-C4 alcohols such as ethyl alcohol, propyl alcohol, or isopropyl alcohol, and most preferably, the organic hydroxy compound is isobutyl alcohol.

[0021] The obtained reaction product of an organic hydroxy compound and phosphorus pentasulfide may contain various residual side reaction products including polysulfides such as polysulfides of diesters of dithiophosphoric acid. 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 defined above, preferably isobutyl alcohol or an isobutyl group), forming a reaction product containing one or more diesters of dithiophosphoric acid and various polysulfide side reaction products including at least the exemplary phosphorus polysulfide species of diisobutyldithiophosphoric acid shown below (wherein 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] [Chemical formula]

[0023] Prior to further reaction, the above reaction product containing at least diesters of dithiophosphoric acid and various residual phosphorus polysulfides is further treated using evaporation or distillation techniques to isolate the desired diesters of dithiophosphoric acid 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 diesters of dithiophosphoric acid. 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, wiped-film evaporative heat exchanger, rising-film evaporator, centrifugal distillation, and the like, or combinations thereof, depending on the requirements of a particular application. One or more of each unit operation may be used in parallel or in series, depending on the requirements of a 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 onto the heated inner surface by the rotor. Volatile components rapidly evaporate (in this case, distillation of the desired dithiolate diester), while non-volatile components (in this case, unwanted polysulfide residual products) are discharged at the bottom outlet. More specifically, a suitable evaporator may include an upright cylindrical vessel in which a vertical rotor shaft extends concentrically within the vessel. The inlet may include one or more wiper assemblies connected to the rotor shaft below a distributor that operates to supply the material to be evaporated to a distributor mechanism that spreads the material in a thin film around the inner wall of the vessel to form a thin film of liquid on the inner wall. Then, the liquid film evaporates due to heating of the inner wall. An internal condenser, which is often placed at the center of the cylindrical body, may be used to condense the distillate phase and collect it in a suitable tank. The non-volatile bottoms containing the unwanted polysulfide component are collected in a separate tank, thereby separating them from the upper volatile material containing the desired dithiolate diester that condenses into the distillate.

[0025] The separation technique involves a selected combination of pressure and temperature of an evaporator or distillation for isolating and separating the desired product. In a method or embodiment, the distillation of the reaction product containing the above mixture of dialkyl dithiophosphates and phosphorus polysulfide may preferably be carried out in a thin-film evaporator or a short-path evaporator. Suitable distillation conditions may include a temperature of at least about 50 °C, at least about 80 °C (preferably about 90 °C to about 120 °C, more preferably about 90 °C to about 105 °C), and 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). The condensate may be recovered from the distillation at a temperature of about 10 °C or less (preferably about 2 °C to about 8 °C, more preferably about 4 °C to about 6 °C). In a method, the distillation may include a split ratio of distillate (recovered as condensate) to bottoms or residue of about 90 - 98% of distillate to about 2 - about 10% of residue or bottoms. In one method using a thin-film evaporator or a centrifugal thin-film evaporator, the residence time of the components of the composition in the heated device is short because distillation and / or evaporation can be carried out relatively quickly by the thin film.

[0026] The condensate from the distillation contains the desired dialkyl dithiophosphate (e.g., dialkyl dithiophosphoric acid) substantially free of phosphorus polysulfide from the reaction product. In one method, the dialkyl dithiophosphoric acid in the condensate may include one or more of dipropyl dithiophosphoric acid, diisopropyl dithiophosphoric acid, dibutyl dithiophosphoric acid, diisobutyl dithiophosphoric acid, or combinations thereof, preferably diisobutyl dithiophosphoric acid. Without wishing to be limited by theory, it is believed that the condensate is substantially free of phosphorus polysulfide from the above-described reaction product, and in such a content, it 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 dialkyl dithiophosphate.

[0027] Next, the condensate from evaporation or distillation, which contains the distilled diester of dithiophosphoric acid, is further reacted in a second step with another organic compound, preferably an unsaturated carboxylic acid, to form the oil-soluble phosphorus antiwear additive of the present disclosure. A wide variety of unsaturated carboxylic acids or fatty acids may be used in this further reaction, including those having other functional groups in addition to the multiple bond. Preferred unsaturated carboxylic acids for the second reaction step may include C1-C20 unsaturated fatty acids such as acrylic acid, methacrylic acid, 2-ethylacrylic acid, or combinations thereof. (As used herein, (meth)acrylic acid refers to either acrylic acid or methacrylic acid.) The reaction may be carried out at about 50°C to about 100°C for about 2 to about 4 hours, or as required to obtain the desired final product. The resulting ashless dithiophosphate antiwear additive may include alkylated dithiophosphate esters such as 3-((di-isobutoxyphosphorothioyl)thio)-2-methylpropanoic acid, 3-((di-isopropoxyphosphorothioyl)thio)-2-methylpropanoic acid, 3-((di-butoxyphosphorothioyl)thio)-2-methylpropanoic acid, 3-((di-propoxyphosphorothioyl)thio)-2-methylpropanoic acid, and similar ashless thiophosphate antiwear additives. An exemplary reaction scheme II for the second reaction step of the condensate is shown below, where R1 is as defined above (preferably an isobutyl group) and R2 is hydrogen or a methyl group (preferably a methyl group):

[0028] [Chemical formula]

[0029] In one method or embodiment, the oil-soluble phosphorus antiwear additive of the present specification may be prepared by reacting the above organic hydroxy compound (preferably isobutyl alcohol) and phosphorus pentasulfide in a first reaction step at a molar ratio of the organic hydroxy compound to phosphorus pentasulfide of about 4:1 to about 10:1 to form a reaction product. The reaction product is then distilled, and a condensate substantially free of the polysulfide phosphorus product is preferably recovered from the distillate containing dialkyldithiophosphoric acid. Then, in a second reaction step, this condensate is further reacted with the above unsaturated carboxylic acid (preferably methacrylic acid), and the molar ratio of the unsaturated carboxylic acid to the organic hydroxy compound is about 0.01:1 to about 0.5:1. The resulting oil-soluble phosphorus antiwear additive may be used in the lubricating composition preferably in an amount of about 0.1 to about 5% by weight, in other methods about 0.1 to about 2.0% by weight, and in further methods about 0.2 to about 0.5% by weight.

[0030] Base oil In one method, suitable base oils for use in the lubricating compositions of the present specification together with the novel ashless antiwear additives include mineral oils, synthetic oils, and all common lubricating base oils. The mineral oil can be naphthenic or paraffinic. The mineral oil can be refined by conventional methods using acids, alkalis, and other agents such as clay or aluminum chloride, or can be an extracted oil produced by solvent extraction using a solvent such as phenol, sulfur dioxide, furfural, or dichlorodiethyl ether. The mineral oil may be hydrotreated or hydrorefined, dewaxed by cooling or a catalytic dewaxing process, or hydrocracked (such as the Yubase® family of hydrocracked base oils manufactured by SK Innovation Co., Ltd. (Seoul, Korea)). The mineral oil 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 of this specification may be selected from Group I to V base oils as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. These three groups of base oils 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. Group III base oils are derived from mineral oils, but it should be noted that due to the rigorous processing these fluids undergo, their physical properties become very similar to those of some true synthetic oils such as PAOs. Thus, oils derived from Group III base oils may be referred to as synthetic fluids in the industry. Suitable oils may be derived from hydrocracked, hydrogenated, hydrofinished, virgin oils, refined oils, and re-refined oils, and 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 various blends of about 0% to about 100% Group I oil, about 0% to about 100% Group II oil, about 0% to about 100% Group III oil, or blends of Group I and II, Group I and III, or Group II and III oils.

[0034] Virgin oils are those derived from natural, mineral, or synthetic sources without or with very little further refining treatment. Refined oils are similar to virgin oils except that they have been treated in one or more refining processes that can bring about improvement in one or more properties. Examples of suitable refining techniques are solvent extraction, secondary distillation, acid or base extraction, filtration, osmosis, etc. Oils refined to a quality suitable for consumption may or may not be useful. Edible oils may sometimes be referred to as white oils. In some embodiments, the lubricating oil composition does not contain edible oil or white oil.

[0035] The refined oil is also known as recycled oil or reprocessed oil. These oils are obtained in the same or a similar process as the refined oil. In many cases, these oils are further processed by techniques aimed at removing used additives and oil decomposition products.

[0036] Mineral oil can include oil obtained by excavation, or from plants and animals, or any mixture thereof. For example, such oils can include 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, and paraffin-based, naphthenic-based, or solvent-treated or acid-treated mineral lubricating oils of the mixed paraffin-naphthene type, but are not limited thereto. Such oils can be partially or fully hydrogenated if desired. Oils derived from coal or shale can also be useful.

[0037] The major amount of base oil contained 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, and the major amount of base oil is other than that resulting from the provision of additive components or viscosity index improvers in the composition. In another embodiment, the major amount of base oil contained 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, and the major amount of base oil is other than that resulting from the provision of additive components or viscosity index improvers in the composition.

[0038] The base oil may also be either a synthetic base oil from API Group IV or V, and / or a combination of a synthetic base oil and a mineral base oil. Useful synthetic lubricating oils include hydrocarbon oils such as polymerized, oligomerized, or interpolymerized olefins (e.g., polybutylene, polypropylene, propylene isobutylene copolymer); 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, and 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 decanephosphonic acid), or polymerized tetrahydrofuran. Synthetic oils can be produced by the Fischer-Tropsch reaction and can typically be hydrogenated isomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, the oil can be prepared by a Fischer-Tropsch gas-liquid synthesis procedure, as well as other gas-liquid oils.

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

[0041] In some methods, the preferred base oil or base oil of lubricating viscosity has less than about 25 ppm sulfur, a viscosity index greater than about 120, and a kinematic viscosity of about 2 to about 8 cSt at about 100 °C. In other approaches, the base oil of lubricating viscosity has less than about 25 ppm sulfur, a viscosity index greater than 120, and a kinematic viscosity of about 4 cSt at 100 °C. The base oil can have a CP (paraffin carbon content) of greater than 40%, greater than 45%, greater than 50%, greater than 55%, or greater than 90%. The base oil can have a CA (aromatic carbon content) of less than 5%, less than 3%, or less than 1%. The base oil can 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 oil can have a ratio of monocyclic naphthenes to dicyclic to hexacyclic naphthenes of less than 2 or less than 1.5 or less than 1.

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

[0043]

Table 2

[0044] The percentages of each of the above components represent the weight % of each component based on the total weight of the final additive or lubricating oil composition. The balance 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 sub-combinations. However, it may be suitable to use an additive concentrate (i.e., an additive plus a diluent such as a hydrocarbon solvent) to blend all of the components simultaneously.

[0045] The lubricating compositions described herein that include the improved ashless dithiophosphate antiwear reaction products of the present disclosure exhibit good antiwear performance (measured by a four-ball test in accordance with ASTM D4172 at 1200 rpm, 40 kg, 75 °C for 1 hour) and at the same time exhibit good copper corrosion performance (measured in accordance with ASTM D130 and ASTM D4951). For example, the lubricating composition 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 composition may exhibit copper corrosion of 150 ppm or less of copper, more preferably 80 ppm or less of copper, in other approaches about 50 ppm or less, about 30 ppm or less, and in some approaches about 5 ppm or less of copper, as measured by ASTM D130 and D4951 in accordance with the examples.

[0046] In one approach, the lubricating compositions of the present disclosure are suitable for use as hydraulic fluids or drive train lubricating compositions and may be used to lubricate mechanical components 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 can 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 use in 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 approaches, the lubricating compositions of the present disclosure that include such additives as described above may also include such components, provided that the one or more optional components and their amounts do not affect the performance characteristics described in the paragraphs above. These optional components are described in the paragraphs below.

[0048] Other phosphorus-containing compounds The lubricant compositions of the present specification may include one or more phosphorus-containing compounds that can impart the advantage of abrasion resistance to fluids. The one or more phosphorus-containing compounds may be present in the lubricating oil composition in an amount in the range of about 0 wt% to about 15 wt%, or about 0.01 wt% to about 10 wt%, or about 0.05 wt% to about 5 wt%, or about 0.1 wt% to about 3 wt% of the lubricating oil composition. The phosphorus-containing compound may provide up to 5000 ppm of phosphorus, or about 50 to about 5000 ppm of phosphorus, or about 300 to about 1500 ppm of phosphorus, or up to 600 ppm of phosphorus, or up to 900 ppm of phosphorus to the lubricant composition.

[0049] The one or more phosphorus-containing compounds may include ashless phosphorus-containing compounds. Examples of suitable phosphorus-containing compounds include, but are not limited to, thiophosphates, dithiophosphates, phosphates, phosphate esters, phosphite esters, phosphites, phosphonates, phosphorus-containing carboxylic acid esters, ethers, or amide salts thereof, and mixtures thereof. The phosphorus-containing antiwear agents are fully described by European Patent No. 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 may sometimes be referred to as dibutyl hydrogen phosphite. It is within the scope of the present invention for the lubricant composition of the present invention to include a phosphorus-containing compound that may be referred to as either a phosphite or a phosphonate.

[0051] In any of the above phosphorus-containing compounds, the compound may have about 5 to about 20 wt% of phosphorus, or about 5 to about 15 wt% of phosphorus, or about 8 to about 16 wt% of phosphorus, or about 6 to about 9 wt% of 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]

Chemical formula

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

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

[0057] In yet another embodiment, the lubricant composition comprises a phosphorus-containing compound of Formula XIV, wherein R1 is O, R2 is OR”, R3 is H, R4 is -OR”, R’’ is C4, and one or more phosphorus-containing compounds are present in an amount that supplies 80-1550 ppm of phosphorus to the lubricant composition.

[0058] In other embodiments, the lubricant composition comprises a phosphorus-containing compound of Formula XIV, wherein R1 is O, R2 is -R”, R3 is -OCH3 or -OH, R4 is -OCH3, R’’ is C18, and one or more phosphorus-containing compounds are present in an amount that supplies 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 supplies 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 that supplies 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 antiwear agents The lubricant composition may also contain other anti-wear agents that are phosphorus-free compounds. Examples of such anti-wear agents include boric acid esters, boric acid epoxides, thiocarbamate compounds (e.g., thiocarbamate esters, alkylene-bonded thiocarbamates, and bis(S-alkyl dithiocarbamyl) disulfides, thiocarbamate amides, thiocarbamic acid ethers, alkylene-bonded thiocarbamates, and bis(S-alkyl dithiocarbamyl) disulfides, and mixtures thereof), sulfurized olefins, tridecyl adipate, titanium compounds, and long-chain derivatives of hydroxycarboxylic acids, such as tartrate derivatives, tartramides, tartrimides, citrates, and mixtures thereof. A preferred thiocarbamate compound is molybdenum dithiocarbamate. Preferred tartrate derivatives or tartrimides may contain an alkyl-ester group where the total number of carbon atoms on the alkyl group can be at least 8. The tartrate derivative or tartrimide may contain an alkyl-ester group where the total number of carbon atoms on the alkyl group can be at least 8. The anti-wear agent may, in one embodiment, contain citrate. Additional anti-wear agents may be present in an amount ranging from about 0 wt% to about 15 wt%, or about 0.01 wt% to about 10 wt%, or about 0.05 wt% to about 5 wt%, or about 0.1 wt% to about 3 wt% of the lubricating oil composition.

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

[0062] A variety of sulfur-containing extreme pressure agents are suitable, including sulfurized animal or vegetable fats or oils, sulfurized animal or vegetable fatty acid esters, complete or partial esterified esters of trivalent or pentavalent acids of phosphorus, sulfurized olefins (see, for example, 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, for example, 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 Pat. No. 1,162,334), functional group-substituted dihydrocarbyl polysulfides (see, for example, U.S. Pat. No. 4,218,332), and polysulfide olefin products (see, for example, U.S. Pat. No. 4,795,576). Other suitable examples include sulfurized olefins, sulfur-containing amino heterocyclic compounds, 5-dimercapto-1,3,4-thiadiazole, polysulfides having a majority of S3 and S4 sulfides, sulfurized fatty acids, sulfurized branched 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 of 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 of 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 of about 0.6 wt% to about 1 wt% based on the total weight of the lubricant composition. In still 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 is a polysulfide composed of one or more compounds represented by the formula: Ra-Sx-Rb, where Ra and Rb are hydrocarbyl groups, each of which can contain from 1 to 18, in another approach from 3 to 18 carbon atoms, and x can range from 2 to 8, typically from 2 to 5, and in particular can be 3. In some approaches, x is an integer from 3 to 5, and about 30 to about 60 percent of x is an integer of 3 or 4. The hydrocarbyl groups can be of various 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 mainly or completely composed of tri-, tetra-, and pentasulfides) can 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 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 weight percent, desirably about 30 to about 50 weight percent. A 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. Patent No. 3,471,404 to Myers, U.S. Patent No. 4,204,969 to Papay et al., U.S. Patent No. 4,954,274 to Zaweski et al., U.S. Patent No. 4,966,720 to DeGonia et al., and U.S. Patent No. 3,703,504 to Horodysky et al., each of which is incorporated herein by reference.

[0066] A process for preparing sulfurized olefins that includes the process disclosed in the aforementioned patent involves the formation of a material typically referred to as an "adduct" by reacting an olefin with 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 weight loss in a copper corrosion test. U.S. Patent 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] Antioxidant 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-naphthylamine, alkylated phenyl-alpha-naphthylamine, hindered non-aromatic amines, phenols, hindered phenols, oil-soluble molybdenum compounds, polymeric antioxidants, or mixtures thereof. The antioxidant compounds can 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 hindrance group. The phenol group may be further substituted with a hydrocarbyl group and / or a crosslinking group bonded 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 or 4-butyl-2,6-di-tert-butylphenol, or 4-dodecyl-2,6-di-tert-butylphenol. In one embodiment, the hindered phenol antioxidant may be an ester and may 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 may 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 may be an ester and may 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 a diarylamine and a phenol, and each antioxidant may be present in an amount sufficient to provide up to about 5 wt% 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% diarylamine and about 0.4 to about 2.5 wt% phenol based on the lubricant composition.

[0070] Examples of suitable olefins that can be sulfided 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. Fatty acids are often obtained 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, fatty acids are obtained from lard oil, tall oil, peanut oil, soybean oil, cottonseed oil, sunflower seed oil, or mixtures thereof. The fatty acids and / or esters can be mixed with olefins such as α - olefins.

[0072] One or more antioxidants can be present in the lubricating oil composition in the range of about 0 wt% to about 20 wt%, or about 0.1 wt% to about 10 wt%, or about 1 wt% to about 5 wt%.

[0073] Dispersant As the dispersant contained in the lubricant composition, an oil-soluble polymer hydrocarbon main chain having a functional group capable of associating with the particles to be dispersed can be mentioned, but it is not limited thereto. Typically, the dispersant often contains an amine, alcohol, amide, or ester polar moiety bonded to the polymer main chain via a crosslinking group. The dispersant can be selected from Mannich dispersants as described in U.S. Patent Nos. 3,634,515, 3,697,574, and 3,736,357, ashless succinimide dispersants as described in U.S. Patent Nos. 4,234,435 and 4,636,322, amine dispersants as described in U.S. Patent Nos. 3,219,666, 3,565,804, and 5,633,326, Koch dispersants as described in U.S. Patent Nos. 5,936,041, 5,643,859, and 5,627,259, and polyalkylene succinimide dispersants as described in U.S. Patent Nos. 5,851,965, 5,853,434, and 5,792,729.

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

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

[0076] Viscosity index improver The lubricant composition of the present specification may also optionally contain one or more viscosity index improvers. Suitable viscosity index improvers may include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutenes, 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, and a preferred example is described in US Patent Application Publication No. 20120101017(A1), which is incorporated herein by reference.

[0077] The lubricating oil composition of the present specification may optionally contain one or more dispersant viscosity index improvers in addition to or instead 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, polymethacrylates functionalized with an amine, or esterified maleic anhydride-styrene copolymers reacted with an amine.

[0078] The total amount of the viscosity index improver and / or the dispersant viscosity index improver may be about 0 wt% to about 20 wt%, about 0.1 wt% to about 15 wt%, about 0.1 wt% to about 12 wt%, or about 0.5 wt% to about 10 wt%, about 3 wt% to about 20 wt%, about 3 wt% to about 15 wt%, about 5 wt% to about 15 wt%, or about 5 wt% to about 10 wt% 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 from about 10,000 to about 500,000, from about 50,000 to about 200,000, or from 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 from about 40,000 to about 500,000, from about 50,000 to about 200,000, or from about 50,000 to about 150,000. In some embodiments, the viscosity index improver is a polymethacrylate having a number average molecular weight of from about 10,000 to about 500,000, from about 50,000 to about 200,000, or from about 50,000 to about 150,000.

[0080] Other optional additives The other additives can be selected to perform one or more of the functions required of the lubricant composition. Further, one or more of the aforementioned additives can be multifunctional and can provide additional functions in addition to the functions described herein, or can provide other functions. The other additives can be added in addition to the additives specified in the present disclosure and / or can include one or more of a metal deactivator, a viscosity index improver, an ashless TBN booster, an antiwear agent, a corrosion inhibitor, a rust inhibitor, a dispersant, a dispersant viscosity index improver, an extreme pressure agent, an antioxidant, an antifoaming agent, a demulsifier, an emulsifier, a pour point depressant, a seal swell agent, and mixtures thereof. Typically, a fully formulated lubricating oil contains one or more of these performance additives.

[0081] Suitable metal deactivators include derivatives of benzotriazole (typically tolyltriazole), dimercaptothiadiazole derivatives, 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole, or 2-alkyldithiobenzothiazole; foam suppressants 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 may be mentioned.

[0082] Suitable foam suppressants include silicon-based compounds such as siloxane.

[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] A suitable rust inhibitor can be a single compound or a mixture of compounds having the property of suppressing corrosion of the ferrous metal surface. 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 serotic acid, and oil-soluble polycarboxylic acids including dimeric and trimeric acids such as those produced from tall oil fatty acid, oleic acid, and linoleic acid. Other suitable corrosion inhibitors include long-chain alpha, omega-dicarboxylic acids in the molecular weight range of about 600 to about 3000, and alkenyl succinic acids having an alkenyl group containing 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 a half-ester of an alkenyl succinic acid having about 8 to about 24 carbon atoms in the alkenyl group and 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, the rust inhibitor can be used in an optional 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 inhibition properties). Suitable copper corrosion inhibitors include ether amines, polyethoxylated compounds such as ethoxylated amines and ethoxylated alcohols, imidazolines, monoalkyl, and dialkyl thiadiazoles.

[0087] Thiazole, triazole, and thiadiazole can also be used in lubricants. 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 1,3,4-thiadiazole, for example, 2-hydrocarbyldithio-5-mercapto-1,3,4-dithiadiazole.

[0088] An anti-foaming agent / surfactant can also be included in the fluid according to the present invention. Various agents for such applications are known. A copolymer of ethyl acrylate and hexyl ethyl acrylate, for example, PC-1244 available from Solutia, can be used. In other embodiments, a silicone fluid such as 4% DCF can be included. A mixture of anti-foaming agents can also be present in the lubricant composition.

Examples

[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 The alkylated diisobutyldithiophosphoric acid of the comparative example was prepared as follows: About 15.6 pounds of isobutanol and about 0.023 pounds of caprolactam (25% in 2-ethylhexanol) were charged into a stainless steel reactor, and then about 11.5 pounds of phosphorus pentasulfide (P2S5 having about 27.7% phosphorus) was slowly charged while maintaining the temperature in the range of about 35 °C to about 77 °C with vigorous stirring. Next, about 34.4 pounds of additional phosphorus pentasulfide was charged into the reactor, and subsequently about 46.8 pounds of isobutanol was slowly added while maintaining the temperature between 35 °C and about 77 °C. After the second isobutanol addition was complete, the reactor was maintained at about 80 °C to about 85 °C for 120 minutes to form reaction product A. Reaction product A was represented by the image in Figure 4 and was considered to contain at least the following structure of diisobutyldithiophosphoric acid and at least the following polysulfide phosphorus species of diisobutyldithiophosphoric acid (x is from 1 to 6):

[0091] [Chemical formula]

[0092] Next, the alkylated diisobutyldithiophosphoric acid reaction product was directly prepared from the above intermediate mixture of diisobutyldithiophosphoric acid and polysulfide phosphorus prepared above as follows: About 81.4 g of methacrylic acid was added dropwise to about 252.4 g of the above reaction product A at about 70 °C over 1 hour and continuously stirred at about 70 °C for about 4 hours. The crude product was dissolved in about 500 mL of 2N sodium hydroxide and washed twice with about 399 mL of petroleum spirit. Then, the solution was acidified to pH 1 using concentrated hydrochloric acid and subjected to extraction with about 150 mL of petroleum spirit. The organic phase was washed with water and concentrated on a rotary evaporator to produce an alkylated diisobutyldithiophosphoric acid antiwear additive of the comparative example containing various polysulfide phosphorus.

[0093] Example 1 The reaction product A containing diisobutyldithiophosphoric 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). The thin-film evaporator was operated under a jacket temperature of about 100 °C and a pressure of about 0.4 Torr. The cooler was cooled to about 5 °C. The evaporator had a split ratio of about 90% distillate and about 10% bottoms or residue. The condensate was recovered as distilled diisobutyldithiophosphoric acid and is represented by the image in Figure 5.

[0094] Next, the alkylated diisobutyldithiophosphoric acid reaction product was prepared from the condensate prepared above as follows: About 81.4 g of methacrylic acid was added dropwise to about 252.4 g of the above condensate at about 70 °C over 1 hour and continuously stirred at about 70 °C for about 4 hours. The crude product was dissolved in about 500 mL of 2N sodium hydroxide and washed twice with about 399 mL of petroleum spirit. Then, the solution was acidified to pH 1 using concentrated hydrochloric acid and subjected to extraction with about 150 mL of petroleum spirit. The organic phase was washed with water and concentrated on a rotary evaporator to produce an alkylated diisobutyldithiophosphoric acid reaction product, which was considered to be substantially free of phosphorus polysulfide.

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

[0096]

Table 3

[0097] Figure 1 shows the phosphorus NMR spectra of the hydraulic working fluids of the comparative examples and the present invention from Table 3, indicating that the hydraulic working fluids of the comparative examples have additional peaks identified in the figure, suggesting the presence of various phosphorus polysulfide compositions not found in the hydraulic working fluids of the present invention.

[0098] Copper corrosion was evaluated over a long period of 2 days at 121 °C according to the method in accordance with ASTM D130. For the test, three coupon containers were prepared per finished fluid (each container containing approximately 45 grams of the finished fluid and a copper strip). At each time point in Table 4, the containers were withdrawn and the solutions were recovered. Then, 2 grams of each solution were subjected to copper corrosion according to ASTM D4951, and the results are shown in Table 4 below.

[0099]

Table 4

[0100] At each treatment rate, the fluid of the present invention showed an improvement of about 50% to about 80% in copper corrosion. The graphs in Figures 2 and 3 also show a dramatic improvement in copper corrosion between the comparative example and the fluid of the present invention.

[0101] The comparative example and the fluid of the present invention were also evaluated for anti-wear performance at 1200 rpm, a weight of 40 KG, 75 °C, and 1 hour in accordance with ASTM D4172. 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 working fluid of the present invention showed a wear scar that was the same as or slightly better than that of the hydraulic working fluid of the comparative example, and as shown above, the copper corrosion was dramatically improved.

[0104] As used in this specification and the appended claims, it should be noted that the singular forms "a", "an", and "the" include plural referents unless explicitly and clearly limited to one referent. Thus, for example, a reference to "an antioxidant" includes two or more different antioxidants. As used herein, the term "comprising" and its grammatical variations are intended to be non-limiting such that the listing of items in a list does not exclude other similar items that may be substituted or added to the items in the list.

[0105] For the purposes of this specification and the appended claims, unless otherwise indicated, all amounts, percentages, or ratios, and all numbers representing other values used in this specification and the claims are to be understood as being modified in all instances by the term "about". Thus, unless otherwise indicated, the numerical parameters set forth in the following specification and the 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 be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0106] It should be understood that each component, compound, substituent, or parameter disclosed herein is disclosed for use alone or in combination with one or more of any other component, compound, substituent, or parameter disclosed herein.

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

[0108] It should be further understood that each lower limit of each range disclosed herein is to be construed as 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 disclosed herein. Accordingly, the present disclosure should be construed as disclosing all ranges derived by combining each lower limit of each range with each upper limit of each range, or with each specific value within each range, or by combining each upper limit of each range with each specific value within each range. That is, it is further understood that any range between the endpoint values within a broader range is also contemplated herein. Accordingly, a range of 1 to 4 also means ranges such as 1 to 3, 1 to 2, 2 to 4, 2 to 3, etc.

[0109] Furthermore, the specific amounts / values of components, compounds, substituents, or parameters disclosed in the description or examples should be construed as a disclosure of either the lower or upper limit of a range, and thus, in combination with any other lower or upper limit or specific amount / value of a range for the same component, compound, substituent, or parameter disclosed elsewhere in the present application, can form a range for that component, compound, substituent, or parameter.

[0110] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or that cannot currently be anticipated by the applicants or other persons of ordinary skill in the art may arise. Accordingly, the filed appended claims, and the appended claims as they may be amended, are intended to embrace all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims

Claim 1 A lubricating composition comprising one or more base oils having a lubricating viscosity, and an oil-soluble phosphorus antiwear 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 carboxylic acid to form the oil-soluble phosphorus antiwear additive: wherein the reaction product contains a diester dithiophosphate having the structure of Formula 1 below, the condensate is a diester dithiophosphate having the structure of Formula 1 below, wherein the content of polysulfide phosphorus derived from the reaction product is less than 1% by weight, Formula 1: 【Chemical 1】 In Formula 1, R1 is a residue derived from the organic hydroxy compound. Claim 2 The lubricating composition according to claim 1, wherein the distillation is carried out at a temperature of at least 50 °C, a pressure of at least 0.1 Torr, or a combination of one or more thereof, and / or the condensate is recovered at a temperature of 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. Claim 3 The lubricating composition according to claim 2, wherein the condensate contains a dialkyldithiophosphate, and the dialkyldithiophosphate contains dipropyldithiophosphate, diisopropyldithiophosphate, dibutyldithiophosphate, diisobutyldithiophosphate, or a combination thereof. Claim 4 The lubricating composition according to claim 1, wherein the unsaturated carboxylic acid is a C1-C20 unsaturated carboxylic acid, and / or the unsaturated carboxylic acid is acrylic acid, methacrylic acid, 2-ethylacrylic acid, or a combination thereof. Claim 5 The organic hydroxy compound is a C1-C6 linear or branched alcohol, a hydroxylaryl 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, the lubricating composition according to claim 1.

6. The organic hydroxy compound is isobutyl alcohol, the reaction product contains diisobutyldithiophosphoric acid and one or more polysulfides of phosphorus, the condensate contains the diisobutyldithiophosphoric acid, substantially does not contain the one or more polysulfides of phosphorus, and the condensate further reacts with methacrylic acid to form the oil-soluble phosphorus antiwear additive, the lubricating composition according to claim 1.

7. The lubricating composition according to claim 1, wherein the lubricating composition contains 0.1 to 5% by weight of the oil-soluble phosphorus antiwear additive.

8. The organic hydroxy compound is provided in a molar ratio of 4:1 to 10:1 with respect to the phosphorus pentasulfide, and / or the unsaturated carboxylic acid is provided in a molar ratio of 0.01:1 to 0.5:1 with respect to the organic hydroxy compound, the lubricating composition according to claim 1.

9. A method for preparing an oil-soluble phosphorus antiwear additive for a lubricating composition, 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; reacting the condensate with an unsaturated carboxylic acid to form the oil-soluble phosphorus antiwear additive. Here, the reaction product contains a dithiophosphoric acid diester having the structure of Formula 1 below; The condensate is a dithiophosphoric acid diester having the structure of Formula 1 below, in which the content of the polysulfide of phosphorus derived from the reaction product is less than 1% by weight; Formula 1: 【Chemical 2】 In Formula 1, R1 is a residue derived from the organic hydroxy compound.

10. The method according to claim 9, wherein the distillation is carried out at a temperature of at least 50 ° C and / or the distillation is carried out at a pressure of at least 0.1 Torr and / or the condensate is recovered at a temperature of 10 ° C or lower 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.

11. The method according to claim 9, wherein the condensate contains dialkyldithiophosphoric acid and / or the dialkyldithiophosphoric acid is dipropyldithiophosphoric acid, diisopropyldithiophosphoric acid, dibutyldithiophosphoric acid, diisobutyldithiophosphoric acid, or a combination thereof.

12. The unsaturated carboxylic acid is a C1-C20 unsaturated carboxylic acid and / or the unsaturated carboxylic acid is acrylic acid, methacrylic acid, 2-ethylacrylic acid, or a combination thereof and / or the organic hydroxy compound is a C1-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, 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. The method according to claim 9.

13. The method according to claim 9, wherein the organic hydroxy compound is isobutyl alcohol, the reaction product contains diisobutyldithiophosphoric acid and one or more phosphorus polysulfides, the condensate contains the diisobutyldithiophosphoric acid, substantially does not contain the one or more phosphorus polysulfides, and the condensate further reacts with methacrylic acid to form the oil-soluble phosphorus antiwear additive.

14. The method according to claim 9, wherein the organic hydroxy compound is provided in a molar ratio of 4:1 to 10:1 with respect to the phosphorus pentasulfide, and / or the unsaturated carboxylic acid is provided in a molar ratio of 0.01:1 to 0.5:1 with respect to the organic hydroxy compound.

15. An oil-soluble phosphorus antiwear additive for a lubricating composition 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 therefrom; and (c) reacting the condensate with an unsaturated carboxylic acid to form an oil-soluble phosphorus antiwear additive. Here, the reaction product contains a dithiophosphoric acid diester having the structure of the following formula 1. The condensate is a dithiophosphoric acid diester having the structure of the following formula 1, wherein the content of polysulfide phosphorus derived from the reaction product is less than 1% by weight. Formula 1: 【Chemical Formula 3】 In Formula 1, R 1 is a residue derived from the organic hydroxy compound.

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