Lubricating compositions for industrial gear fluids

Abstract

A gear fluid composition for lubricating a transmission system, the gear fluid composition comprising a combination of a short-chain polysulfide extreme pressure agent and a long-chain polysulfide extreme pressure agent to minimize sulfur loss and maintain high extreme pressure performance.

Description

Technical Field

[0001] The present disclosure relates to lubricating compositions having improved extreme pressure, friction and / or sulfur retention properties for use in driveline applications including, for example, gears, axles and / or power transmission fluids. Background Art

[0002] Gears, transmissions and / or axles used in heavy-duty or industrial applications often require lubricants that provide specific friction characteristics suitable for the desired application. For example, axles, transfer cases, differentials and transmissions are commonly found in many heavy-duty or industrial vehicles, and each requires a unique lubricating composition. In practice, gears and axles used in such applications may operate at full load capacity and / or frequently stop-and-go operations, placing additional stresses and strains on the hardware. Therefore, lubricants used in heavy-duty or industrial gear and axle applications require chemical additives to reliably protect the gears and axles under full load and stop-and-go operating conditions.

[0003] Generally, the lubricant used for such applications needs, for example, fluids that meet one or more performance characteristics of extreme pressure, anti-wear, friction and / or copper corrosion, to suggest some common requirements of axle or gear fluids. Multiple additives may be included in the lubricant to achieve such performance. For example, such lubricants typically include sulfurized additives to protect gears and other components from wear and tear and notching. However, sulfur additives commonly used in such gear oils tend to volatilize, causing a certain amount of sulfur to be lost over time. Due to a variety of reasons, including extreme pressure performance degradation and potential environmental issues, sulfur loss is undesirable. Summary of the invention

[0004] In one method or embodiment, a lubricant composition for a transmission system providing good extreme pressure and low sulfur loss is described herein. In one aspect, the lubricating composition comprises (a) a first polysulfide extreme pressure agent, the first polysulfide extreme pressure agent comprising a C2-C6 polysulfide mixture containing a majority of trisulfides; (b) a second polysulfide extreme pressure agent, the second polysulfide extreme pressure agent comprising a C10-C14 polysulfide mixture containing a majority of trisulfides; and wherein the weight ratio of sulfur contributed by the first polysulfide and the second polysulfide is from about 0.3 to about 0.8.

[0005] In other methods or embodiments, the lubricant composition of the preceding paragraph may be combined with one or more optional features, methods or embodiments. These optional features or embodiments may include one or more of the following: wherein the first polysulfide and the second polysulfide provide about 0.2 wt % to about 0.5 wt % sulfur to the lubricating composition; and / or wherein the first polysulfide has about 40 wt % to about 50 wt % sulfur and the second polysulfide has about 18 wt % to about 30 wt % sulfur; and / or wherein the first polysulfide has about 1 mol % to about 10 mol % disulfides and about 51 mol % to about 95 mol % trisulfides; and / or wherein the second polysulfide has about 1 mol % to about 10 mol % disulfides and about 51 mol % to about 95 mol % trisulfides; and / or wherein the first polysulfide has the formula R1-S x -R2, wherein R1 and R2 are independently C4 to C6 hydrocarbon groups, and x is an integer of at least 2, and most x is 3; and / or wherein R1 and R2 are each C4 hydrocarbon groups; and / or wherein the first polysulfide comprises di-tert-butyl polysulfide; and / or wherein the second polysulfide has the formula R3-S y -R4 structure, wherein R3 and R4 are independently C10 to C14 hydrocarbon groups, and y is an integer of at least 2, and most of y are 3; and / or wherein R3 and R4 are each a C12 hydrocarbon group; and / or wherein the second polysulfide comprises di-tert-dodecyl polysulfide; and / or wherein the lubricant composition has a sulfur loss of less than about 30 wt. % as measured in accordance with ASTM D2893 and greater than about 200 kgf as measured by a 4-ball test according to ASTM D2596; and / or further comprises about 0.2 wt. % to about 0.4 wt. % of the first polysulfide and about 0.8 wt. % to about 1.2 wt. % of the second polysulfide; and / or further has a weight percent ratio of the first polysulfide to the second polysulfide of about 0.2 to about 0.38.

[0006] In other methods or embodiments of the present disclosure, a method of lubricating a transmission system to provide good extreme pressure performance and maintain low sulfur loss is described herein. In one aspect of this embodiment, the method includes lubricating a transmission system component with a lubricating composition, the lubricating composition comprising a first polysulfide extreme pressure agent and a second polysulfide extreme pressure agent, the first polysulfide extreme pressure agent comprising a C2-C6 polysulfide mixture containing a majority of trisulfides, the second polysulfide extreme pressure agent comprising a C10-C14 polysulfide mixture containing a majority of trisulfides, and wherein the weight ratio of sulfur contributed by the first polysulfide and the second polysulfide is from about 0.3 to about 0.8.

[0007] In other methods or embodiments, the method of the preceding paragraph may be combined with one or more optional steps, features, or embodiments in any combination. These optional features or embodiments of the method may include one or more of the following: wherein the first polysulfide and the second polysulfide provide about 0.2 wt % to about 0.5 wt % sulfur to the lubricating composition; and / or wherein the first polysulfide has the formula R1-S x -R2 structure, wherein R1 and R2 are independently C4 to C6 hydrocarbon groups, and x is an integer of at least 2, and most x is 3; and / or wherein the second polysulfide has the formula R3-S y -R4, wherein R3 and R4 are independently C10 to C14 hydrocarbon groups, and y is an integer of at least 2, and most y is 3; and / or wherein the first polysulfide comprises di-tert-butyl polysulfide; and / or wherein the second polysulfide comprises di-tert-dodecyl polysulfide; and / or wherein the lubricant composition has a sulfur loss of less than about 30 wt. % as measured in accordance with ASTM D2893 and greater than about 200 kgf as measured in accordance with a 4-ball test of ASTM D2596.

[0008] In further embodiments or methods, there is provided use of any embodiment of a lubricant as described herein to form a lubricant composition and / or a lubricated transmission system composition and also having a sulfur loss of less than about 30 wt % as measured according to ASTM D2893 and / or greater than about 200 kgf according to a 4-ball test of ASTM D2596.

[0009] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.The following term definitions are provided to clarify the meaning of certain terms as 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 as discussed herein and a minor amount of an additive composition as discussed herein. Such gear fluids are used in extreme pressure situations, such as in transmissions and gear drive components having metal-to-metal contact situations, such as in transmissions, turbines, and / or limited slip differentials.

[0011] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense, which 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 predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from a hydrocarbon substituent and a hydrocarbon substituent containing one or more halogen groups, hydroxyl groups, alkoxy groups, mercapto groups, nitro groups, nitroso groups, amino groups, pyridyl groups, furanyl groups, imidazolyl groups, oxygen and nitrogen substitutions, and wherein there are no more than two non-hydrocarbon substituents for every ten carbon atoms in the hydrocarbyl group.

[0012] As used herein, unless otherwise expressly stated, the term "weight percent" or "weight %" means the percentage of the component by weight of the entire composition. Unless otherwise stated, all percentages herein are weight percentages.

[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 capable of being suspended in oil in all proportions. However, the aforementioned terms do mean that they are, for example, 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 employed. In addition, the additional incorporation of other additives may also allow for the incorporation of higher levels of a particular additive, if desired.

[0014] As used herein, the term "alkyl" refers to a straight chain, branched, cyclic and / or substituted saturated chain portion of about 1 to about 200 carbon atoms. As used herein, the term "alkenyl" refers to a straight chain, branched, cyclic and / or substituted unsaturated chain portion of about 3 to about 30 carbon atoms. As used herein, the term "aryl" refers to monocyclic and polycyclic aromatic compounds, which may include alkyl, alkenyl, alkylaryl, amino, hydroxyl, alkoxy, halogen substituents and / or heteroatoms including, but not limited to, nitrogen and oxygen.

[0015] As used herein, molecular weight is determined by gel permeation chromatography (GPC) using commercially available polystyrene standards (having an Mn of about 180 to about 18,000 as a calibration reference). The molecular weight (Mn) of any embodiment herein can be measured using an instrument such as a gel permeation chromatography (GPC) instrument obtained from Waters, and the data processed using software such as Waters Empower software. The GPC instrument can be equipped with a Waters separation module and a Waters refractive index detector (or similar optional equipment). GPC operating conditions can include a guard column, 4 Agilent PLgel columns (length 300×7.5 mm; particle size 5μ, and pore size range ), the column temperature is about 40 ° C. Unstabilized HPLC grade tetrahydrofuran (THF) can be used as a solvent with a flow rate of 1.0 mL / min. The GPC instrument can be calibrated with commercially available polystyrene (PS) standards with a narrow molecular weight distribution ranging from 500 g / mol to 380,000 g / mol. For samples with a mass of less than 500 g / mol, the calibration curve can be extrapolated. Samples and PS standards can be dissolved in THF and prepared at a concentration of 0.1 wt % to 0.5 wt % and can be used without filtration. GPC measurements are also described in US 5,266,223, which is incorporated herein by reference. The GPC method also provides molecular weight distribution information; see, for example, WW Yau, JJ Kirkland and DD Bly, "Modern Size Exclusion Liquid Chromatography", John Wiley and Sons, New York, 1979, which is also incorporated herein by reference.

[0016] As used herein, any sulfur moiety distribution or ratio is used 13 CNMR was measured on a Bruker Avance-3 HD 500 MHz instrument equipped with a 5 mm BBO Prodigy probe (or equivalent). The sample was dissolved in chloroform-d and 1 H NMR one-dimensional (1D) and two-dimensional (2D) homonuclear experiments were about 3% wt / wt and for 13 C 1D and 2D heteronuclear experiments were about 30% wt / wt. Chloroform-d was used as the chemical shift reference, d H =7.27 and d C =77.0ppm. The experiment was carried out at ambient temperature. 13 C NMR experiments used ninety-degree pulse width, 5x T1 delay and gating 1 H decoupling and direct observation of 1D under quantitative conditions 1 H and 13 C- 1H decoupling experiments. In addition, distortion-free enhanced polarization transfer (DEPT) experiments using the 135 degree pulse option were obtained. 2D experiments used to aid in structure assignment were homonuclear correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlation (HMBC). All NMR data were acquired using Bruker Topspin 3.62 software from Bruker Inc of Billerica MA and processed using ACD / Spectrus Processor 2021.1.3 software from Advanced Chemistry Development, Inc. using standard parameters (or equivalent equipment / software).

[0017] It should be understood that throughout this disclosure, the terms "comprising," "including," "containing," and the like are considered open ended and include any elements, steps, or ingredients not expressly listed. The phrase "consisting essentially of" is meant to include any expressly listed elements, steps, or ingredients as well as any additional elements, steps, or ingredients that do not materially affect the basic and novel aspects of the invention. The present disclosure also contemplates that any composition described using the terms "comprising," "including," "containing" is also to be interpreted as including disclosure of the same composition "consisting essentially of" or "consisting of" its specifically listed components. DETAILED DESCRIPTION

[0018] In one method or embodiment, disclosed herein is a lubricating composition suitable for gear fluid, power transmission fluid and / or axle applications, the lubricating composition having up to about 1.0 wt % sulfur provided by a mixture of polysulfide extreme pressure agents (in other methods, the lubricant may have about 0.2 wt % to about 1.0 wt % sulfur, about 0.2 wt % to about 0.75 wt % sulfur, or about 0.2 wt % to about 0.5 wt % sulfur from a mixture of polysulfide extreme pressure agents). The sulfur provided by the polysulfide extreme pressure agent has a certain sulfur moiety distribution, and each polysulfide of the mixture has a certain organic moiety distribution thereon. In one aspect, the lubricating composition herein has a combination of at least two or more polysulfide extreme pressure agents, each polysulfide extreme pressure agent having a selected sulfur moiety and a selected organic moiety structure, the polysulfide extreme pressure agent being configured to minimize sulfur volatility and maintain high extreme pressure performance in the lubricating composition.

[0019] In one method or embodiment, the lubricant composition of the present invention comprises a first polysulfide extreme pressure agent and a second polysulfide extreme pressure agent, wherein the first polysulfide extreme pressure agent comprises a mixture of short chain polysulfides (such as C2-C6 polysulfides), wherein most of the first polysulfides are trisulfides, and the second polysulfide extreme pressure agent comprises a mixture of long chain polysulfides (such as C10-C14 polysulfides), wherein most of the second polysulfides are also trisulfides. In one aspect of the embodiment of the present invention, the lubricating composition also has a weight ratio of sulfur contributed by the first polysulfide and the second polysulfide of about 0.3 to about 0.8. The lubricating composition comprising a mixture of such polysulfide extreme pressure agents has a sulfur loss of less than about 30% by weight (as shown in the following examples, measured according to the S200 oxidation test of ASTM D2893) and a 4-ball test of greater than about 200 kgf according to ASTM D2596.

[0020] In some methods and embodiments, the first polysulfide extreme pressure agent has the formula R1-S x -R2 structure, wherein R1 and R2 are independently short chain hydrocarbon groups, such as C4 to C6 hydrocarbon groups, and x is an integer of at least 2 (i.e., at least disulfide), and most x integers are 3 (i.e., mainly trisulfide). In other methods or embodiments, the second polysulfide extreme pressure agent has the formula R3-S y -R4 structure, wherein R3 and R4 are independently long chain hydrocarbon groups, such as C10 to C14 hydrocarbon groups, and y is an integer of at least 2 (i.e., at least disulfide), and most y integers are 3 (i.e., mainly trisulfide). Therefore, each polysulfide extreme pressure agent is a compound having at least -S2- part, wherein most polysulfides have -S3- part. In some methods, each polysulfide extreme pressure agent in the polysulfide extreme pressure agent of the present invention can also have less than about 1% by weight of -S4- and higher parts. As discussed in detail below, the selected sulfur content contributes to extreme pressure performance, and the selected organic group, especially the ratio of short chain organic group and long chain organic group, contributes to sulfur retention.

[0021] The first polysulfide extreme pressure agent

[0022] The first polysulfide extreme pressure agent (also referred to herein as EP agent A) is a polysulfide having the formula R1-S x-R2 structure of dialkyl sulfide compound, wherein R1 and R2 are independently short chain hydrocarbon groups, preferably C2 to C6 hydrocarbon groups (in other methods, C3 to C6 hydrocarbon groups or C4 to C6 hydrocarbon groups), and x is an integer of at least 2, and preferably most of the x integers are 3. That is, each hydrocarbon group of the first polysulfide extreme pressure agent has 2 to 6 carbon atoms, preferably 4 to 6 carbon atoms, or more preferably 4 carbon atoms. In the method, each hydrocarbon group of the organic sulfide compound can be aromatic or aliphatic, preferably, the hydrocarbon group can be an aliphatic group, such as alkyl, alkenyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, cycloalkenyl, etc., most preferably, the hydrocarbon group is an alkyl group with a specified amount of carbon atoms. Suitable alkyl groups can be linear or branched ethyl, propyl, butyl, pentyl and / or hexyl groups. As discussed in more detail below, the hydrocarbyl group may be derived from a suitable olefin and may have 2 to 6 carbon atoms or other ranges as described above. Preferably, the first polysulfide extreme pressure agent has a C4 hydrocarbyl group, most preferably, is di-tert-butyl polysulfide.

[0023] Suitable olefins for preparing the first polysulfide extreme pressure agent of this invention can be monosubstituted monoolefins or disubstituted monoolefins containing 2 to 6 carbon atoms. Disubstituted monoolefins are olefins with at least one double bond carbon atom containing two alkyl substituents. Examples of suitable olefins for deriving the first polysulfide extreme pressure agent include ethylene, propylene, butylene, isobutylene, 2-methyl-2-pentene, 2-methyl-2-butene, 2-methyl-1-butene, diisobutylene, triisobutylene and mixtures thereof, as well as dimers, trimers, tetramers and mixtures thereof, so that the polysulfide formed has C2 to C6 organic groups thereon.

[0024] In the method or embodiment, the first polysulfide extreme pressure agent can be prepared by reacting a predetermined amount of molten sulfur with a desired olefin under high pressure conditions in the presence of an aqueous sodium hydrosulfide solution. Preferably, the sulfur source used to form the first polysulfide is substantially free of sulfur chloride, hydrogen sulfide, and combinations thereof, and in this context, the reaction herein has about 0.1% by weight or less, about 0.05% by weight or less, about 0.01% by weight or less of sulfur chloride, hydrogen sulfide, etc., or does not contain sulfur chloride, hydrogen sulfide, etc. The first polysulfide extreme pressure agent can be obtained at a temperature of about 75°C to about 300°C, preferably about 120°C to about 220°C, more preferably about 120°C to about 150°C. Suitable molar ratios of sulfur to hydrosulfide can be in the range of about 20:1 to about 0.25:1. The molar ratio of sulfur plus hydrosulfide to olefin can be in the range of about 5:1 to about 0.5:1. High pressure can vary between about 100psig to 2000psig or more. The reaction time is variable and can be in the range of about 2 hours to about 24 hours, preferably less than about 8 hours, and can be 1 hour to 4 hours. Although any suitable olefin can be used, it is necessary to select olefins to achieve short-chain hydrocarbyl groups as described above. For example, as required, olefins containing 2 to about 6 carbons are useful raw materials for obtaining the desired short-chain hydrocarbyl groups in the final product, and preferably isobutylene is used for the first polysulfide extreme pressure agent. The selected olefin or mixture of olefins can optionally react with a preformed mixture of a sulfided aqueous solution of hydrosulfide (prepared by direct sulfidation of an aqueous solution of sodium hydrosulfide). The reaction can be appropriately carried out by adding reactants in sequence. An aqueous solution of an alkali metal or alkaline earth metal salt of any suitable hydrosulfide can be used. An aqueous solution of sodium hydrosulfide is preferred, and a concentrated solution of sodium hydrosulfide is preferred compared to a dilute solution.

[0025] In some methods or embodiments, the polysulfide product formed by the above reaction can then be treated with an aqueous solution of caustic (i.e., sodium hydroxide) and / or an alkali metal sulfide (such as sodium sulfide or potassium sulfide, and in some cases, sodium sulfide), which can be prepared, for example, by mixing an aqueous sodium hydrosulfide solution with a caustic solution (such as an aqueous sodium hydroxide solution) in an amount effective to produce the desired sulfide distribution / ratio in the final product. The caustic can be a 40% to 60% solution of a metal hydroxide (such as sodium hydroxide). The solution can contain a co-solvent, such as methanol. The caustic and / or sodium sulfide solution and the polysulfide formed above can be combined in a stirred reactor and heated at a temperature of up to about 100° C., such as about 50° C. to about 100° C. (preferably about 90° C. to about 100° C.) under an inert atmosphere (such as nitrogen) for about 30 minutes to about 4 hours, and in some cases, for about 1 hour to about 2 hours. The reaction mixture is then cooled and the organic product separated at the upper portion of the aqueous layer is recovered. The amount of caustic can vary depending on the needs of each of the various reaction products formed and their sulfur distribution / ratios. Alternatively, the polysulfide product formed above can be distilled using suitable distillation equipment to collect suitable fractions containing trisulfide and disulfide contents as described herein.

[0026] The first polysulfide extreme pressure agent formed is mainly trisulfide, and can have about 1 mol % to about 10 mol % of disulfide, about 51 mol % to about 99 mol % of trisulfide and about 1 mol % or less of tetrasulfide or higher sulfide. In other methods or embodiments, the first polysulfide extreme pressure agent has about 51 mol % to about 95 mol % of trisulfide, about 65 mol % to about 95 mol % of trisulfide, about 75 mol % to about 95 mol % of trisulfide or about 85 mol % to about 95 mol % of trisulfide. In other methods or embodiments, the first polysulfide extreme pressure agent can also have about 40 wt % to about 50 wt % of sulfur by weight, in other methods, about 42 wt % to about 48 wt % of sulfur, or in other other methods, about 42 wt % to about 46 wt % of sulfur. As described above, any embodiment of the first polysulfide extreme pressure agent herein has the short-chain organic group, which is preferably a C2 to C6 hydrocarbon group, more preferably a C3 to C6 hydrocarbon group, even more preferably a C4 hydrocarbon group, and most preferably a tert-butyl group.

[0027] Second polysulfide extreme pressure agent

[0028] The second polysulfide extreme pressure agent (also referred to herein as EP agent B) is also a dialkyl sulfide compound and has the formula R3-S y-R4 structure, wherein R3 and R4 are independently long chain hydrocarbon groups, preferably C10 to C14 hydrocarbon groups, and y is an integer of at least 2 (and preferably most y integers are 3). That is, each hydrocarbon group of the second polysulfide extreme pressure agent has 10 to 14 carbon atoms, preferably 12 to 14 carbon atoms, or more preferably 12 carbon atoms. In the method, each hydrocarbon group of the second organic sulfide compound can be aromatic or aliphatic, preferably, the hydrocarbon group can be an aliphatic group, such as alkyl, alkenyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, cycloalkenyl, etc., most preferably, the hydrocarbon group is an alkyl group with a specified amount of carbon atoms. The alkyl group suitable for the second polysulfide extreme pressure agent can be a linear or branched decyl, undecyl, dodecyl, tridecyl and / or tetradecyl group. In such methods, the hydrocarbyl group may be derived from a suitable olefin and / or hydrocarbyl mercaptan, which may have 10 to 14 carbon atoms or other ranges as described above. Preferably, the second polysulfide extreme pressure agent has a C12 hydrocarbyl group, most preferably, di-tert-dodecyl polysulfide.

[0029] In one embodiment, the second polysulfide extreme pressure agent can be prepared from elemental sulfur and suitable hydrocarbyl mercaptan. Suitable mercaptan for preparing the second polysulfide extreme pressure agent herein can be mercaptan containing 10 to 14 carbon atoms. Examples of suitable mercaptan include those with linear or branched decene, undecene, dodecene, tridecene, tetradecene olefinic groups and dimers, trimers, tetramers and mixtures thereof, so that the formed polysulfide has C10 to C14 organic groups thereon.

[0030] In the method or embodiment, the second polysulfide extreme pressure agent of the present invention can be prepared by the following steps: optionally reacting one or more of the above-mentioned multiple hydrocarbyl mercaptans with a sulfur source (preferably, elemental sulfur or molten sulfur) in the presence or absence of a catalyst (such as an optional alkylamine catalyst) under superatmospheric pressure, and then removing low-boiling materials. Preferably, the sulfur source for the second polysulfide is also substantially free of sulfur chloride, hydrogen sulfide and combinations thereof, and in this context, the reaction herein has about 0.1% by weight or less, about 0.05% by weight or less, about 0.01% by weight or less of sulfur chloride, hydrogen sulfide, etc., or does not contain sulfur chloride, hydrogen sulfide, etc.

[0031] In an embodiment, the second polysulfide extreme pressure agent of the present invention can be obtained, for example, by combining or reacting a hydrocarbyl mercaptan with elemental sulfur in a certain ratio (including but not limited to a ratio of about 2:1 to about 1:2 of moles of hydrocarbyl mercaptan to grams of sulfur) in an autoclave or other reaction vessel suitable for superatmospheric pressure and high temperature reaction. In the method, the reaction can be carried out at a temperature of about 80°C to about 200°C, a pressure of about 250psi to about 1,000psi, and a reaction time of about 2 hours to about 30 hours (or as needed) until the elemental sulfur is consumed to reach the desired sulfur level of the polysulfide.

[0032] The reaction can be carried out in the presence or absence of a catalyst. If a catalyst is used, a suitable catalyst can include amines and sulfur compounds, such as dithiocarbamates and mercaptans, such as but not limited to n-butylamine, n-octylamine, triethylamine, tetramethylthiuram disulfide and mercaptobenzothiazole, etc. If necessary but not limited to catalyst, the catalyst can be used with an amount of about 0.01% by weight to about 5.0% by weight of the reaction mixture or other amounts suitable for specific applications and sulfur levels. The reaction can be carried out in the absence of oxygen. In some methods, the reaction can include a non-reactive solvent, such as heptane, methylene dichloride, etc. or a combination thereof.

[0033] In some methods or embodiments, the above-mentioned sulfided product can then be treated with an aqueous solution of caustic (sodium hydroxide) and / or alkali metal sulfide (such as sodium sulfide or potassium sulfide, and in some cases, sodium sulfide), which can be prepared, for example, by mixing an aqueous sodium hydrosulfide solution with a caustic solution (such as an aqueous sodium hydroxide solution) in an amount effective to produce the desired sulfide distribution / ratio. The solution may contain a co-solvent, such as methanol. The caustic and / or sodium sulfide solution and the sulfided intermediate can be combined in a stirred reactor and heated at a temperature of up to about 100° C., such as about 50° C. to about 100° C., for about 30 minutes to about 4 hours, and in some cases, for about 1 hour to about 2 hours under an inert atmosphere (such as nitrogen). The reaction mixture is then cooled and the organic product separated in the upper part of the water layer is recovered. In the method, the caustic solution can be an alkali metal hydroxide (i.e., sodium hydroxide) of about 40% by weight to about 60% by weight. The amount of caustic can also vary according to the need to form each of the reaction products in the various reaction products and the sulfur distribution / ratio herein. Alternatively, the formed sulfided polysulfide may also be distilled using suitable distillation equipment to collect suitable fractions containing the trisulfide and disulfide contents described herein.

[0034] The second polysulfide extreme pressure agent formed has a majority of trisulfide groups and may have about 1 mol % to about 10 mol % of disulfide, about 51 mol % to about 99 mol % of trisulfide and about 1 mol % or less of tetrasulfide or higher sulfide. In other methods or embodiments, the second polysulfide extreme pressure agent may have about 51 mol % to about 95 mol % of trisulfide, about 65 mol % to about 95 mol % of trisulfide, about 75 mol % to about 95 mol % of trisulfide or about 85 mol % to about 95 mol % of trisulfide. In some methods or embodiments, the second polysulfide extreme pressure agent has about 18 wt % to about 30 wt % of sulfur by weight, in other methods, about 18 wt % to about 28 wt % of sulfur, or in other methods, about 20 wt % to about 26 wt % of sulfur. As described above, any of the embodiments herein of the second polysulfide extreme pressure agent has the long chain organic group, which is preferably a C10 to C14 hydrocarbon group, more preferably a C12 hydrocarbon group, and most preferably a tert-dodecyl group.

[0035] Lubricating composition

[0036] The lubricating composition herein comprises a mixture of a first polysulfide extreme pressure agent and a second polysulfide extreme pressure agent as described above, and the amounts of the first polysulfide extreme pressure agent and the second polysulfide extreme pressure agent are configured to minimize any sulfur loss and maintain high extreme pressure performance. In a method or embodiment, for example, the lubricating composition comprises (a) a first polysulfide extreme pressure agent and (b) a second polysulfide extreme pressure agent, the first polysulfide extreme pressure agent comprising a C2-C6 polysulfide mixture containing a majority of trisulfides as described above, and the second polysulfide extreme pressure agent comprising a C10-C14 polysulfide mixture containing a majority of trisulfides also as described above.

[0037] The first polysulfide extreme pressure agent and the second polysulfide extreme pressure agent combined can provide up to about 1 weight % sulfur to the lubricating composition, preferably about 0.2 weight % to about 0.5 weight % sulfur (in other methods, about 0.3 weight % to about 0.4 weight % sulfur). In some methods or embodiments, sulfur is provided by each polysulfide at a specific sulfur ratio, which is configured to achieve low sulfur loss and maintain extreme pressure performance. In an embodiment, the weight ratio of sulfur contributed by the first polysulfide and the second polysulfide is about 0.3 to about 0.8, in other embodiments, about 0.4 to about 0.8, and in other embodiments, about 0.45 to about 0.75.

[0038] In yet other methods or embodiments, a certain treatment rate or weight percent of the polysulfide extreme pressure agent in the lubricant composition herein may include (a) about 0.2 weight percent to about 0.4 weight percent of the first polysulfide (EP agent A) and (b) about 0.8 weight percent to about 1.2 weight percent of the second polysulfide (EP agent B). In other methods, the weight percent ratio of the first polysulfide to the second polysulfide may be about 0.2 to about 0.38.

[0039] This combination of the first polysulfide extreme pressure agent and the second polysulfide extreme pressure agent enables the lubricant composition herein to have a sulfur loss of less than about 30 wt% (as shown in the following examples, measured in accordance with the S200 oxidation test of ASTM D2893) and a high extreme pressure performance of greater than about 200 kgf according to the 4-ball test of ASTM D2596. In other methods, the sulfur loss of the lubricant herein is only about 20 wt% to about 30 wt% (or about 21 wt% to 28 wt%), and the 4-ball performance is relatively strong, at about 200 kgf to about 225 kgf.

[0040] Base oil

[0041] In one approach, suitable base oils for the lubricating compositions or gear fluids herein include mineral oils, synthetic oils, and include all common mineral oil base stocks. The mineral oil may be a naphthenic oil or a paraffinic oil. The mineral oil may be refined by conventional methods using acids, alkalis, and clays or other reagents such as aluminum chloride, or may be an extracted oil, produced, for example, by solvent extraction with solvents such as phenol, sulfur dioxide, furfural, or dichlorodiethyl ether. The mineral oil may be hydrotreated or hydrofined, dewaxed by cooling or catalytic dewaxing processes, or hydrocracking, such as from SK Innovation Co., Ltd. (Seoul, Korea). A series of hydrocracked base oils. Mineral oils may be produced from natural crude oil sources or consist of isomerized wax materials or residues of other refining processes.

[0042] The base oil or base oil of lubricating viscosity used in the composition herein may be selected from any suitable base oil for transmission or gear oil applications. Examples include base oils in Class IV as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. The three classes of base oils are as follows:

[0043] Table 1: Base oil types

[0044]

[0045] Class I, Class II and Class III are mineral oil processing raw materials, can be preferably used for the transmission system or gear fluid of the present application.It should be noted that although Class III base oil is derived from mineral oil, the strict processing of these fluid experiences causes their physical properties to be very similar to some real synthetic oils, such as PAO.Therefore, the oil derived from Class III base oil can be called synthetic fluid in industry.Suitable oil can be derived from hydrocracking, hydrogenation, hydrofining, unrefined, refined and re-refined oil and its mixture.In some methods, base oil can be a blend of Class I oil and Class II oil, and blend can be about 0% to about 100% Class I oil, about 0% to about 100% Class II oil, about 0% to about 100% Class III oil, or Class I and Class II, various blends of Class I and Class III, or Class II and Class III oil blends.

[0046] Unrefined oils are those derived from natural, mineral or synthetic sources with little or no further purification. Refined oils are similar to unrefined oils, except that they have been subjected to one or more purification steps, which may result in improvements in one or more properties. Examples of suitable purification techniques are 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 referred to as white oils. In some embodiments, the lubricating oil composition does not contain edible oils or white oils.

[0047] Re-refined oils are also called reclaimed oils or reprocessed oils. Similar to refined oils, these oils are obtained using the same or similar processes. Typically these oils are further processed by techniques directed to the removal of spent additives and oil breakdown products.

[0048] Mineral oil can comprise the oil obtained by drilling or the oil from plant and animal or any mixture thereof.For example, this type of oil can include but is not limited to castor oil, lard, olive oil, peanut oil, corn oil, soybean oil and linseed oil, and mineral lubricating oil, such as liquid petroleum and solvent-treated or acid-treated paraffin, cycloalkane or mixed paraffin-cycloalkane type mineral lubricating oil.If desired, this type of oil can be partially or completely hydrogenated.Oil derived from coal or shale can also be applicable.

[0049] The major amount of base oil included in the gear fluid herein may be selected from the group consisting of Group I, Group II, Group III, and a combination of two or more of the foregoing, and wherein the major amount of base oil is not a base oil resulting from providing an additive component or a viscosity index improver 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 a combination of two or more of the foregoing, and wherein the major amount of base oil is not a base oil resulting from providing an additive component or a viscosity index improver in the composition.

[0050] The base oil may also be any synthetic base oil. Useful synthetic lubricating oils may include hydrocarbon oils such as polymerized, oligomeric or copolymerized olefins (e.g., polybutene, polypropylene, propylene isobutylene copolymers); poly(1-hexene), poly(1-octene), 1-decene trimers or oligomers, such as poly(1-decene), such materials are generally 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 derivatives, analogs, and homologs thereof, or mixtures thereof. Polyalphaolefins are typically hydrogenated materials.

[0051] Other synthetic lubricating oils include polyol esters, diesters, liquid esters (e.g., diethyl esters of toluene phosphate, trioctyl phosphate and decanephosphonic acid) or polytetrahydrofurans containing phosphoric acid. Synthetic oils can be produced by Fischer-Tropsch reaction and can generally be Fischer-Tropsch hydrocarbons or waxes of hydroisomerization. In one embodiment, oil can be prepared by Fischer-Tropsch gas-liquid synthesis procedures and other gas-liquid oils.

[0052] In the compositions herein, the amount of base oil of lubricating viscosity may be the remainder remaining after the sum of the amounts of performance additives is subtracted from 100 wt%. For example, the oil of lubricating viscosity that may be present in the finished fluid may be a "major amount", such as greater than about 50 wt%, greater than about 60 wt%, greater than about 70 wt%, greater than about 80 wt%, greater than about 85 wt%, greater than about 90 wt%, or greater than about 95 wt%.

[0053] In some methods, the preferred base oil or base oil of lubricating viscosity has less than about 25ppm sulfur, a viscosity index greater than about 120ppm, and a kinematic viscosity of about 2cSt to about 8cSt at about 100°C. In other methods, the base oil of lubricating viscosity has less than about 25ppm sulfur, a viscosity index greater than 120, and a kinematic viscosity of about 4cSt at 100°C. The base oil may have a CP (paraffinic carbon content) greater than 40%, greater than 45%, greater than 50%, greater than 55%, or greater than 90%. The base oil may have a CA (aromatic carbon content) less than 5%, less than 3%, or less than 1%. The base oil may have a CN (naphthenic carbon content) less than 60%, less than 55%, less than 50%, or less than 50% and greater than 30%. The base oil may have a ratio of 1-ring naphthenes to 2-6-ring naphthenes less than 2 or less than 1.5 or less than 1.

[0054] Suitable driveline, axle or gear lubricant compositions herein may include additive components within the ranges listed in Table 2 below.

[0055] Table 2: Suitable and preferred driveline, axle or gear fluid compositions

[0056]

[0057]

[0058] The percentages of each component above represent the weight percentage of each component based on the weight of the total 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 to formulate the compositions described herein can be blended into the base oil or solvent individually or in various sub-combinations. However, it may be appropriate to use an additive concentrate (i.e., additives plus diluents, such as hydrocarbon solvents) to blend all components simultaneously.

[0059] The lubricating compositions described herein can be formulated to provide lubrication, enhanced friction properties, and improved copper corrosion for various applications. The transmission system lubricating compositions herein can be used to lubricate machine parts, such as gears. 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 gears, helical gears, worm gears, rack gears, involute gears, bevel gears, helical gears, planetary gears, and hypoid gears, as well as limited slip applications and differentials. The transmission system lubricating compositions disclosed herein are also suitable for automatic or manual transmissions, including stepped automatic transmissions, continuously variable transmissions, semi-automatic transmissions, automated manual transmissions, toroidal transmissions, and dual clutch transmissions. The transmission system lubricating compositions herein are particularly suitable for axles, transfer cases, differentials, such as straight differentials, steering differentials, limited slip differentials, clutch-type differentials, and locking differentials, etc.

[0060] Optional additives

[0061] In other methods, the lubricant containing such additives as described above may also contain one or more optional components, as long as such components and their amounts do not affect the performance characteristics as described in the above paragraphs. These optional components are described in the following paragraphs.

[0062] Phosphorus compounds

[0063] The lubricant composition of this invention may include one or more phosphorus-containing compounds that can impart anti-wear benefits to the fluid. The one or more phosphorus-containing compounds are present in an amount of about 0% to about 15% by weight of the lubricant composition, or about 0.01% to about 10% by weight, or about 0.05% to about 5% by weight, or about 0.1% to about 3% by weight of the lubricant composition. The phosphorus-containing compound can provide up to 5000ppm of phosphorus, or about 50 to about 5000ppm of phosphorus, or about 300 to about 1500ppm of phosphorus, or up to 600ppm of phosphorus, or up to 900ppm of phosphorus to the lubricant composition.

[0064] 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, phosphate esters, phosphites, phosphonates, phosphorus-containing carboxylates, ethers or amides thereof and mixtures thereof. Phosphorus-containing antiwear agents are more fully described in European Patent 0612839.

[0065] It should be noted that the terms phosphonate and phosphite are often used interchangeably in the lubricant industry. For example, dibutyl hydrogen phosphonate is often referred to as dibutyl hydrogen phosphite. It is within the scope of the present invention that the lubricant composition of the present invention includes a phosphorus-containing compound that may be referred to as a phosphite or a phosphonate.

[0066] In any of the above phosphorus-containing compounds, the compound can have from about 5 wt % to about 20 wt % phosphorus, or from about 5 wt % to about 15 wt % phosphorus, or from about 8 wt % to about 16 wt % phosphorus, or from about 6 wt % to about 9 wt % phosphorus.

[0067] Phosphorus-containing compounds and above-mentioned dispersant combinations are added to lubricant compositions unexpectedly to give lubricant compositions with positive friction characteristics, such as low friction coefficient. In some cases, the effect of the present invention is even more remarkable when phosphorus-containing compounds themselves give fluid negative friction characteristics. When these relatively poor phosphorus-containing compounds that reduce friction are combined with olefin copolymer dispersants as described herein, lubricant compositions have improved, i.e., lower friction coefficients. That is, the dispersant herein tends to transform the fluid containing phosphorus-containing compounds with relatively poor friction coefficients into a fluid with improved friction properties.

[0068] This improvement in the friction properties of lubricating compositions comprising the phosphorus-containing compounds and olefin copolymer dispersants described herein is surprising because the friction performance of the fluids is superior to combinations of phosphorus-containing compounds with other types of dispersants, including polyisobutylene succinimide dispersants and olefin copolymer succinimide dispersants, which do not have the specified properties of the above-mentioned copolymers.

[0069] Another type of phosphorus-containing compound that imparts improved friction characteristics to the lubricating composition when combined with the olefin copolymer dispersants herein is an ashless (metal-free) phosphorus-containing compound.

[0070] In some embodiments, the ash-free phosphorus-containing compound may be dialkyl dithiophosphate, amyl phosphate, diamyl phosphate, dibutyl hydrogen phosphonate, dimethyl octadecylphosphonate, salts thereof, and mixtures thereof.

[0071] The ashless phosphorus-containing compound may have the formula:

[0072]

[0073] 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 to C3 branched or straight alkyl chain; and R" is a C1 to C18 hydrocarbon chain. When the phosphorus-containing compound has the structure shown in Formula XIV, the compound can have from about 8 to about 16 weight percent phosphorus.

[0074] 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 wherein the phosphorus-containing compound is present in an amount to deliver 80 ppm to 900 ppm of phosphorus to the lubricant composition.

[0075] 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 wherein the phosphorus-containing compound is present in an amount to deliver 80 ppm to 1500 ppm of phosphorus to the lubricant composition.

[0076] In 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 wherein the one or more phosphorus-containing compounds are present in an amount to deliver 80 ppm to 1550 ppm of phosphorus to the lubricant composition.

[0077] 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 wherein the one or more phosphorus-containing compounds are present in an amount to deliver 80 ppm to 850 ppm of phosphorus to the lubricant composition.

[0078] In some embodiments, the phosphorus-containing compound has a structure as shown in Formula XIV and delivers from about 80 ppm to about 4500 ppm of phosphorus to the lubricant composition. In other embodiments, the phosphorus-containing compound is present in an amount that delivers from about 150 ppm to about 1500 ppm of phosphorus, or from about 300 ppm to about 900 ppm of phosphorus, or from about 800 ppm to 1600 ppm of phosphorus, or from about 900 ppm to about 1800 ppm of phosphorus to the lubricant composition.

[0079] Antiwear Agents

[0080] The lubricant composition may also include an antiwear agent that is a phosphorus-free compound. Examples of such antiwear agents include boric acid esters, boric acid ester epoxides, thiocarbamate compounds (including thiocarbamates, alkylene-coupled thiocarbamates and bis (S-alkyl dithiocarbamoyl) disulfides, thiocarbamate amides, thiocarbamate ethers, alkylene-coupled thiocarbamates and bis (S-alkyl dithiocarbamoyl) disulfides and mixtures thereof), sulfided olefins, tridecyl adipates, titanium compounds and long-chain derivatives of hydroxycarboxylic acids, such as tartrate derivatives, tartrate amides, tartrimides, citrates and mixtures thereof. Suitable thiocarbamate compounds are dithiocarbamate platinum. Suitable tartrate derivatives or tartrimides may contain alkyl ester groups, wherein the total number of carbon atoms on the alkyl group may be at least 8. Tartrate derivatives or tartrimides may contain alkyl ester groups, wherein the total number of carbon atoms on the alkyl group may be at least 8. In one embodiment, the antiwear agent may include citric acid esters. Additional antiwear agents may be present in a range comprising 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.

[0081] Extreme Pressure Agents

[0082] The lubricant compositions of the present disclosure may also include other extreme pressure agents, so long as the lubricating compositions herein include the noted amounts and distributions described herein. The optional extreme pressure agent may contain sulfur, and may contain at least 12 weight percent sulfur.

[0083] A variety of sulfur-containing extreme pressure agents are suitable and include 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 (see, 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 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 organic sulfur compounds selected from 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.

[0084] In some embodiments, the extreme pressure agent is present in the lubricating composition in an amount of 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 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 lubricant composition. In other embodiments, the extreme pressure agent is present in an amount between about 0.6 wt % and about 1 wt % based on the total lubricant composition. In other embodiments, the detergent is present in an amount of about 1.0 wt % based on the total lubricant composition.

[0085] One class of suitable extreme pressure agents is a polysulfide composed of one or more compounds represented by the formula: Ra—Sx—Rb, wherein Ra and Rb are hydrocarbyl groups, each of which may contain 1 to 18 and in other methods 3 to 18 carbon atoms, and x may be in the range of 2 to 8, typically in the range of 2 to 5, especially 3. In certain methods, x is an integer from 3 to 5, wherein about 30% to about 60% of x is an integer of 3 or 4. The hydrocarbyl group may be of widely different 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 consisting mainly or entirely of tris, tetras and pentasulfides) may be used. Examples of other useful dihydrocarbyl polysulfides include diamyl polysulfide, dinonyl polysulfide, dodecyl polysulfide and dibenzyl polysulfide.

[0086] Another suitable extreme pressure agent is a sulfurized isobutylene prepared by reacting an olefin such as isobutylene with sulfur. Sulfurized isobutylene (SIB), particularly sulfurized polyisobutylene, typically has a sulfur content of about 10% to about 55%, desirably about 30% to about 50%, by weight. A variety of other olefins or unsaturated hydrocarbons, such as isobutylene dimers or trimers, 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.

[0087] Methods for preparing sulphurized olefins, including methods disclosed in the above-mentioned patents, generally include forming a material commonly referred to as an "adduct", wherein the olefin reacts with a sulphur halide such as sulphur monochloride. The adduct is then reacted with a sulphur source to provide the sulphurized olefin. The quality of the sulphurized olefin is generally measured by various physical properties, including, for example, viscosity, sulphur content, halogen content and copper corrosion test weight loss. U.S. Patent No. 4,966,720 relates to sulphurized olefins used as extreme pressure additives in lubricating oils, and to a two-step reaction for their preparation.

[0088] Antioxidants

[0089] The lubricating oil composition herein may also optionally contain one or more antioxidants. Antioxidant compounds are known and include, for example, phenates, phenate sulfides, sulfided olefins, phosphorus sulfided terpenes, sulfided esters, aromatic amines, alkylated diphenylamines (e.g., nonyl diphenylamine, dinonyl diphenylamine, octyl diphenylamine, dioctyl diphenylamine), phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, hindered non-aromatic amines, phenols, hindered phenols, oil-soluble molybdenum compounds, macromolecular antioxidants, or mixtures thereof. The antioxidant compounds may be used alone or in combination.

[0090] The hindered phenol antioxidant may contain a sec-butyl and / or tert-butyl group as a sterically hindered group. The phenol group may be further substituted with a hydrocarbyl group and / or a bridging group connected 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, BASF commercially available L-135 or the addition product derived from 2,6-di-tert-butylphenol and an alkyl acrylate, wherein 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 the esters available from Albemarle Corporation. 4716.

[0091] Useful antioxidants may include diarylamines and phenols. In one embodiment, the lubricating oil composition may contain a mixture of diarylamines and phenols such that each antioxidant may be present in an amount sufficient to provide up to about 5 weight percent based on the weight of the lubricant composition. In one embodiment, the antioxidant may be a mixture of about 0.3 weight percent to about 1.5 weight percent diarylamine and about 0.4 weight percent to about 2.5 weight percent phenol based on the lubricant composition.

[0092] 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, nonadecaene, or mixtures thereof. In one embodiment, hexadecene, heptadecene, octadecene, nonadecaene, or mixtures thereof, and dimers, trimers, and tetramers thereof are particularly suitable 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).

[0093] Another class of sulphurized olefins includes sulphurized fatty acids and esters thereof. Fatty acids are usually obtained from vegetable oils or animal oils and usually contain about 4 to about 22 carbon atoms. Examples of suitable fatty acids and esters thereof include triglycerides, oleic acid, linoleic acid, palmitoleic acid or mixtures thereof. Usually, fatty acids are obtained from lard, pine oil, peanut oil, soybean oil, cottonseed oil, sunflower oil or mixtures thereof. Fatty acids and / or esters can be mixed with olefins such as alpha-olefins.

[0094] The one or more antioxidants may be present in a 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 % of the lubricating oil composition.

[0095] Dispersants

[0096] Dispersants contained in the lubricant composition may include, but are not limited to, oil-soluble polymeric hydrocarbon backbones 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, typically via a bridging group. The dispersant may be selected from Mannich dispersants as described in U.S. Pat. Nos. 3,634,515, 3,697,574, and 3,736,357; ashless succinimide dispersants as described in U.S. Pat. Nos. 4,234,435 and 4,636,322; amine dispersants as described in U.S. Pat. Nos. 3,219,666, 3,565,804, and 5,633,326; Koch dispersants as described in U.S. Pat. Nos. 5,936,041, 5,643,859, and 5,627,259; and U.S. Pat. Nos. 5,851,965; 5,853,434; and 5,792,729.

[0097] 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 with ethylene-propylene copolymer. Another additional dispersant may be a high molecular weight ester or half ester amide.

[0098] If present, additional dispersants may 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 may be used may be from about 0.1 wt % to about 10 wt %, or from about 0.1 wt % to about 10 wt %, or from about 3 wt % to about 8 wt %, or from about 1 wt % to about 6 wt %, based on the final weight of the lubricating oil composition.

[0099] Viscosity Index Improver

[0100] The lubricant composition herein may also optionally contain one or more viscosity index improvers. Suitable viscosity index improvers may include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutylene, 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 alkenyl aryl conjugated diene copolymers, or mixtures thereof. Other viscosity index improvers may include star polymers, and suitable examples are described in U.S. Publication No. 20120101017A1, which is incorporated herein by reference.

[0101] The lubricating oil compositions herein may optionally contain one or more dispersant viscosity index improvers in addition to or in place of the viscosity index improvers. Suitable viscosity index improvers may include functionalized polyolefins, for example, ethylene-propylene copolymers that have been functionalized with the reaction product of an acylating agent (such as maleic anhydride) and an amine; polymethacrylates functionalized with amines, or esterified maleic anhydride-styrene copolymers reacted with amines.

[0102] The total amount of viscosity index improver and / or dispersant viscosity index improver can be from about 0 wt % to about 20 wt %, from about 0.1 wt % to about 15 wt %, from about 0.1 wt % to about 12 wt %, or from about 0.5 wt % to about 10 wt %, from about 3 wt % to about 20 wt %, from about 3 wt % to about 15 wt %, from about 5 wt % to about 15 wt %, or from about 5 wt % to about 10 wt % of the lubricating oil composition.

[0103] 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.

[0104] Other optional additives

[0105] Other additives can be selected to perform one or more functions required by the lubricant composition. In addition, one or more of the additives mentioned can be multifunctional and provide functions other than those specified herein or different from those specified herein. These other additives can be additives other than the specified additives of the present disclosure and / or can include one or more of the following: metal deactivators, viscosity index improvers, ashless TBN promoters, antiwear agents, corrosion inhibitors, rust inhibitors, dispersants, dispersant viscosity index improvers, extreme pressure agents, antioxidants, foam inhibitors, demulsifiers, emulsifiers, pour point depressants, seal swelling agents and mixtures thereof. Typically, a fully formulated lubricating oil will contain one or more of these additives.

[0106] Suitable metal deactivators may include derivatives of benzotriazole (typically tolyltriazole), dithiothiadiazole derivatives, 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole or 2-alkyldithiobenzothiazole; foam inhibitors including copolymers of ethyl acrylate and 2-ethylhexyl acrylate and optionally vinyl acetate; demulsifiers including trialkyl phosphates, polyethylene glycol, polyethylene oxide, polypropylene oxide and (ethylene oxide-propylene oxide) polymers; pour point depressants including esters of maleic anhydride-styrene, polymethacrylates, polyacrylates or polyacrylamides.

[0107] Suitable foam suppressors include silicon-based compounds such as siloxanes.

[0108] Suitable pour point depressants may include polymethyl methacrylate or mixtures thereof. The pour point depressant may be present in an amount sufficient to provide about 0 wt % to about 1 wt %, about 0.01 wt % to about 0.5 wt %, or about 0.02 wt % to about 0.04 wt % based on the final weight of the lubricating oil composition.

[0109] Suitable rust inhibitors can be single compounds or compound mixtures having the property of inhibiting corrosion of ferrous metal surfaces. Non-limiting examples of useful rust inhibitors 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; and oil-soluble polycarboxylic acids including dimer acids and trimer acids, such as those produced by pine oil fatty acids, oleic acid, and linoleic acid. Other suitable corrosion inhibitors include long-chain α, ω-dicarboxylic acids with a molecular weight ranging from about 600 to about 3000, and alkenyl succinic acids in which the alkenyl group contains about 10 or more carbon atoms, such as tetrapropylene succinic acid, tetradecene succinic acid, and hexadecene succinic acid. Another type of acidic corrosion inhibitor available is a half ester of alkenyl succinic acid and an alcohol (such as polyethylene glycol) having about 8 to about 24 carbon atoms in the alkenyl group. 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 contains no rust inhibitors.

[0110] Rust inhibitors, if present, may be used in optional amounts 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.

[0111] 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 etheramines, polyethoxylated compounds such as ethoxylated amines and ethoxylated alcohols, imidazolines, mono- and di-alkylthiadiazoles, and the like.

[0112] Thiazoles, triazoles, and thiadiazoles may also be used in lubricants. Examples include benzotriazole, tolyltriazole, octyltriazole, decyltriazole; dodecyltriazole, 2-mercaptobenzotriazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercapto-5-alkylthio-1,3,4-thiadiazole, and 2-mercapto-5-alkyldithio-1,3,4-thiadiazole. In one embodiment, the lubricant composition includes a 1,3,4-thiadiazole, such as 2-alkyldithio-5-mercapto-1,3,4-dithiadiazole.

[0113] Defoamers / surfactants may also be included in the fluids according to the present invention. Various agents are known for such purposes. Copolymers of ethyl acrylate and hexyl acrylate may be used, such as PC-1244 available from Solutia. In other embodiments, silicone fluids may be included, such as 4% DCF. A mixture of defoamers may also be present in the lubricant composition.

[0114] Example

[0115] The following examples are illustrations of exemplary embodiments of the present disclosure. In these examples, and elsewhere in this application, unless otherwise stated, all ratios, parts and percentages are by weight. It is intended to present these examples only for illustrative purposes, and is not intended to limit the scope of the invention disclosed herein.

[0116] Example 1

[0117] EP Agent A : Di-tert-butyl polysulfide suitable for use in the short-chain polysulfide or first polysulfide extreme pressure agent of the present invention can be prepared as follows: an aqueous sodium hydrosulfide solution and molten sulfur at a temperature of about 130°C can be charged into a high-pressure reactor. Isobutylene can then be added to the stirred mixture by a high-pressure pump, and the reaction temperature is maintained at about 130°C to about 170°C. After the addition of isobutylene, the reaction can be heated to about 150°C to about 170°C for about 120 minutes. Then, the heating can be stopped and the reactor can be cooled to about 90°C to about 100°C, while excess isobutylene can be discharged. The aqueous phase can be separated and the organic phase can be placed under vacuum to remove residual water. The organic product can be filtered through diatomaceous earth as needed. Additional organic products can be recovered by the following steps: extracting the aqueous byproduct with several portions of hexane, combining the extracts and evaporating the hexane.

[0118] The crude organic product can be combined with 50% aqueous sodium hydroxide solution in a suitable flask equipped with a mechanical stirrer. The mixture can be stirred and heated to at least about 90°C (or about 90°C to about 110°C) for 1 hour (or about 3 hours at most), the mixture is cooled, and the mixture can then be transferred to a separatory funnel. The aqueous phase can be removed and the organic product can be washed with water twice as required. The organic product can be transferred to another flask, sparged with nitrogen, and optionally heated to at least about 100°C again, for about 1.5 hours at most. The organic product can be cooled to room temperature under nitrogen sparge, and then, if necessary, the organic product can be filtered by diatomaceous earth. Alternatively, the crude organic product can be distilled, and the suitable fraction containing the specified trisulfide and disulfide content can be collected.

[0119] An exemplary short chain di-tert-butyl polysulfide suitable for the first polysulfide extreme pressure agent can be prepared by the above method and can include a majority of trisulfides having about 43 wt % to about 47 wt % sulfur. The sulfide distribution can be as described above. 13 CNMR confirmed.

[0120] EP Agent B: Di-tert-dodecyl polysulfide, which is a long-chain polysulfide or second polysulfide extreme pressure agent suitable for use herein, can be prepared as follows: Sulfur and tert-dodecyl sulfide can be charged into a stainless steel autoclave. Optionally, an amine or other suitable catalyst can be co-charged with a non-reactive solvent (such as heptane or dichloromethane). The reaction can be heated to a temperature between ambient temperature (i.e., about 25° C.) and about 100° C. until all elemental sulfur is consumed. Volatile organics can be removed by vacuum stripping, and the organic product containing di-tert-dodecyl polysulfide can then be treated with 50% caustic, or fractionated as described in Example 1 to obtain a product that is primarily a trisulfide.

[0121] An exemplary long chain di-tert-dodecyl polysulfide suitable for use as the second polysulfide extreme pressure agent can be prepared by the above method and can include a majority of trisulfides having about 20 wt % to about 23 wt % sulfur. The sulfide distribution can be as described above. 13 CNMR confirmed.

[0122] The first polysulfide extreme pressure agent and the second polysulfide extreme pressure agent, which can be obtained by the above method for EP agent A and EP agent B, respectively, were evaluated in the lubricating composition of Table 3 and tested for extreme pressure (ASTM D2596) and sulfur loss percentage (ASTM D2893). The lubricating composition of Table 3, in addition to the polysulfide extreme pressure agent, also contains the same amount of additive package with the same detergent, friction modifier, viscosity modifier, antioxidant, rust inhibitor, corrosion inhibitor, seal swell agent and defoamer. The comparative composition and the composition of the present invention may also contain a base oil and / or process oil balanced as needed to achieve a target KV100 of about 10 cSt to 14 cSt.

[0123] Table 3

[0124] C-1 C-2 C-3 I-1 I-2 EP Agent B, %S 21.5 21.5 21.5 21.5 21.5 EP agent A, %S 44.8 44.8 44.8 44.8 44.8 EP agent B, weight % 0.5 0.7 0.9 1 1 EP agent A, weight % 0.35 0.35 0.35 0.35 0.25 Sulfur from polysulfides % 0.26 0.31 0.35 0.37 0.33 Treatment rate ratio* 0.70 0.50 0.39 0.35 0.25 % Sulfur Ratio** 1.46 1.04 0.81 0.73 0.52 % Sulfur Loss*** 33 32 31 28 21 4-ball average**** - - - 220 215 Failed Failed Failed pass pass

[0125] *Treatment ratio is the ratio of the weight % of EP agent A to the weight % of EP agent B

[0126] **Sulfur ratio is the ratio of the weight % of sulfur from EP agent A to the weight % of sulfur from EP agent B

[0127] ***Sulfur loss was measured by ICP before and after running the S200 oxidation test (ASTM D2893). %Sulfur loss is calculated as (SOT%S-EOT%S) / SOT%S*100, where SOT is the start of the test and EOT is the end of the test.

[0128] ****ASTM D2596 (Fresh lubricant before aging / oxidation testing - greater than 200 kgf is expected)

[0129] As shown in Table 3 above, only the lubricating compositions of Fluid 1 and Fluid 2 of the present invention, in which the blend of the short-chain polysulfide extreme pressure agent and the long-chain polysulfide extreme pressure agent has a selected sulfur ratio, passed the extreme pressure test and maintained a low sulfur loss of less than 30%. All comparative fluids have a high level of sulfur loss. It is preferred to have a 4-ball extreme pressure of at least about 200 kgf, and more importantly, to control and minimize sulfur loss after aging, which may lead to a decrease in extreme pressure performance and / or tend to adversely cause various environmental problems.

[0130] 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 affirmatively limited to one referent. Thus, for example, 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 recitation of items in a list does not exclude other like items that can be substituted or added to the listed items.

[0131] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers and other numerical values ​​used in the specification and claims indicating quantities, percentages or ratios should be understood to be modified in all cases by the term "about". Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that may vary depending on the desired properties sought to be obtained by the present disclosure. At a minimum, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted in light of the number of reported significant figures and by applying ordinary rounding techniques.

[0132] It should be understood that each component, compound, substituent or parameter disclosed herein should be interpreted as disclosed for use alone or in combination with one or more of each of the other components, compounds, substituents or parameters disclosed herein.

[0133] It should be further understood that each range disclosed herein should be interpreted as a disclosure of each specific value within the disclosed range with the same number of significant figures. Thus, for example, a range of 1 to 4 should be interpreted as an explicit disclosure of the values ​​1, 2, 3, and 4, as well as any range of such values.

[0134] It should be further understood that each lower limit of each scope disclosed herein should be interpreted as being disclosed in combination with each upper limit of each scope disclosed herein for the same component, compound, substituent or parameter and each specific value in each scope. Therefore, the disclosure should be interpreted as being disclosed by combining each lower limit of each scope with each upper limit of each scope or with each specific value in each scope, or by combining each upper limit of each scope with each specific value in each scope. That is, it should also be further understood that any scope between the endpoint values ​​in a wide range is also discussed herein. Therefore, the scope of 1 to 4 also means the scope of 1 to 3, 1 to 2, 2 to 4, 2 to 3, etc.

[0135] In addition, a specific amount / value of a component, compound, substituent or parameter disclosed in this specification or the examples should be interpreted as a disclosure of a lower or upper limit of a range, and therefore can be combined 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 this disclosure to form a range for that component, compound, substituent or parameter.

[0136] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently foreseen or may not currently be foreseen may occur to applicants or other persons skilled in the art. Therefore, the appended claims as filed and as they may be amended are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims

1. A lubricant composition, comprising: a) a first polysulfide extreme pressure agent, the first polysulfide extreme pressure agent comprising a C2-C6 polysulfide mixture containing 51 mol % to 99 mol % of trisulfide, wherein the first polysulfide has a formula R1-S x -R2 structure, wherein R1 and R2 are independently C2 to C6 hydrocarbon groups, and x is an integer of at least 2; b) a second polysulfide extreme pressure agent, the second polysulfide extreme pressure agent comprising a C10-C14 polysulfide mixture containing 51 mol % to 99 mol % of trisulfide, wherein the second polysulfide has a formula of R3-S y -R4 structure, wherein R3 and R4 are independently a C10 to C14 hydrocarbon group, and y is an integer of at least 2; and The weight ratio of sulfur contributed by the first polysulfide to that contributed by the second polysulfide is 0.3 to 0.

8.

2. The lubricant composition of claim 1, wherein the first polysulfide and the second polysulfide provide 0.2 wt% to 0.5 wt% sulfur to the lubricant composition.

3. The lubricant composition of claim 2, wherein the first polysulfide has 40 wt% to 50 wt% sulfur, and the second polysulfide has 18 wt% to 30 wt% sulfur.

4. The lubricant composition of claim 1, wherein the first polysulfide has 1 mol% to 10 mol% of disulfide and 51 mol% to 95 mol% of trisulfide. 5 . The lubricant composition of claim 1 , wherein the second polysulfide has 1 mol % to 10 mol % of disulfide and 51 mol % to 95 mol % of trisulfide.

6. The lubricant composition of claim 1, wherein R1 and R2 are independently C4 to C6 hydrocarbon groups.

7. The lubricant composition according to claim 6, wherein R1 and R2 are each a C4 hydrocarbon group.

8. The lubricant composition of claim 1, wherein the first polysulfide comprises di-tert-butyl polysulfide.

9. The lubricant composition of claim 1, wherein R3 and R4 are each a C12 hydrocarbon group.

10. The lubricant composition of claim 1, wherein the second polysulfide comprises di-tert-dodecyl polysulfide.

11. The lubricant composition of claim 1, wherein the lubricant composition has a sulfur loss of less than 30 wt% as measured according to ASTM D2893 and a high extreme pressure performance of greater than 200 kgf according to a 4-ball test of ASTM D2596. 12 . The lubricant composition of claim 1 , further comprising 0.2 wt % to 0.4 wt % of the first polysulfide and 0.8 wt % to 1.2 wt % of the second polysulfide.

13. The lubricant composition of claim 12, further having a weight percent of the first polysulfide to the second polysulfide of 0.2 to 0.

38.

14. A method of lubricating a transmission system, the method comprising lubricating a transmission system component with a lubricant composition, the lubricant composition comprising a first polysulfide extreme pressure agent and a second polysulfide extreme pressure agent, the first polysulfide extreme pressure agent comprising a C2-C6 polysulfide mixture containing 51 mol % to 99 mol % of trisulfide, wherein the first polysulfide has a formula R1-S x -R2 structure, wherein R1 and R2 are independently C2 to C6 hydrocarbon groups, and x is an integer of at least 2. The second polysulfide extreme pressure agent comprises a C10-C14 polysulfide mixture containing 51 mol % to 99 mol % of trisulfide, wherein the second polysulfide has the formula R3-S y -R4 structure, wherein R3 and R4 are independently a C10 to C14 hydrocarbon group, and y is an integer of at least 2, and wherein the weight ratio of sulfur contributed by the first polysulfide and the second polysulfide is 0.3 to 0.

8.

15. The method of claim 14, wherein the first polysulfide and the second polysulfide provide 0.2 wt% to 0.5 wt% sulfur to the lubricant composition.

16. The method of claim 14, wherein R1 and R2 are independently C4 to C6 hydrocarbon groups.

17. The method of claim 14, wherein the first polysulfide comprises di-tert-butyl polysulfide.

18. The method of claim 17, wherein the second polysulfide comprises di-tert-dodecyl polysulfide.

19. The method of claim 14, wherein the lubricant composition has a sulfur loss of less than 30 wt% as measured according to ASTM D2893 and a high extreme pressure performance of greater than 200 kgf according to a 4-ball test of ASTM D2596.

20. The method of claim 18, wherein the lubricant composition has a sulfur loss of less than 30 wt% as measured according to ASTM D2893 and a high extreme pressure performance of greater than 200 kgf according to a 4-ball test of ASTM D2596.

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