Engine oil with low-temperature pumpability

Abstract

The present invention provides a lubricating composition comprising a polymer blend of a modified styrene-maleic anhydride copolymer and a poly(meth)acrylate copolymer that effectively maintains a pumpable fluid at low temperatures.

Description

Technical Field

[0001] The present disclosure relates to lubricants comprising a polymer blend that effectively provides improved viscosity characteristics at low temperatures, such as temperatures as low as about -40 °C. Background Art

[0002] Engine oils or lubricants intended for use in automotive and diesel engines typically comprise a base oil having lubricating viscosity and one or more additives. Modern industrial standards place increasingly high demands on the low-temperature performance of such engine oils. Low-temperature characteristics can be measured, for example, by Brookfield viscosity, cold crank simulator test (CCS), pour point, and mini rotary viscometer test (MRV), to name just a few performance parameters.

[0003] The low-temperature performance of engine oils can be improved by selecting the additives used to formulate the oil. Pour point depressants are a common type of additive included in formulated engine oils to help improve the fluidity of the oil at low temperatures. The pour point is a measure of the temperature at which a sample of the lubricant begins to flow and can be determined as described in ASTM D 5950. In many cases, when engine oils have a low pour point, they can also have other good low-temperature characteristics, such as a low cloud point, a low cold filter plugging point, and / or a low-temperature starting viscosity. However, in some cases, formulated oils that exhibit satisfactory low-temperature performance in terms of pour point can still exhibit unsatisfactory low-temperature viscosity characteristics. In fact, it has been found that formulated engine oils fail to pass critical low-temperature viscosity characteristics such as the mini rotary viscometer test (MRV), despite passing the specifications established for the oil regarding cloud point and / or pour point.

[0004] The mini rotary viscometer test (MRV) evaluates the mechanism of low-temperature pumpability of a fluid and is a low-shear rate measurement. The MRV is measured by ASTM D 4684 and can also be referred to as the low-temperature pumping viscosity. In the MRV evaluation, the sample is pre-treated to have a specific thermal history, which can include heating, slow cooling, and soak cycles. The MRV test measures the apparent yield stress and viscosity, which, if greater than a threshold, indicate potential lubricant pumpability problems.

[0005] Summary of the Invention and Terminology

[0006] In one method or embodiment, described herein is a low-temperature stable lubricating composition that exhibits good pumpability, wherein the pumpability is measured at about -40 °C in accordance with the MRV test of ASTM D4684. In the method, the composition comprises a base oil having lubricating viscosity and a polymer additive that effectively maintains a pumpable fluid, including a blend of a modified styrene-maleic anhydride copolymer and a poly(meth)acrylate copolymer.

[0007] In other methods, the low-temperature stable lubricating composition of the previous paragraph may also include any combination of a number of optional features. These optional features include one or more of the following: wherein the lubricating composition further comprises one or more of a succinimide dispersant, a borated succinimide dispersant, a highly basic calcium sulfonate, a highly basic magnesium sulfonate, a zinc dialkyldithiophosphate, an alkylated diphenylamine antioxidant, an antifoaming agent, or a combination thereof; and / or wherein the modified styrene-maleic anhydride copolymer is an esterified styrene-maleic anhydride copolymer; and / or wherein the esterified styrene-maleic anhydride copolymer is esterified with a long-chain alcohol having an alkyl chain length of 10 to 24 carbons; and / or wherein the esterified styrene-maleic anhydride copolymer has a number average molecular weight of about 10,000 to about 100,000; and / or wherein the poly(meth)acrylate copolymer comprises a reactant selected from C1 to C24 linear or branched (meth)acrylate alkyl ester reactants; and / or wherein the poly(meth)acrylate copolymer has a number average molecular weight of about 20,000 or higher; and / or wherein the lubricating composition comprises about 1 wt% or less, preferably about 0.5 wt% to about 0.6 wt% of a polymer additive blend; and / or wherein the ratio of the modified styrene-maleic anhydride copolymer to the poly(meth)acrylate copolymer is about 1:2 to about 1:0.7; and / or wherein the polymer additive blend comprises about 40 wt% to about 60 wt% of the modified styrene-maleic anhydride copolymer based on the total weight of the modified styrene-maleic anhydride copolymer and the poly(meth)acrylate copolymer.

[0008] In other methods or embodiments, a method for maintaining the pumpable viscosity of a lubricating composition using the MRV test according to ASTM D4684 is also described herein. In the method, the method includes adding an additive of any of the foregoing paragraphs of the present disclosure that effectively maintains a pumpable fluid to the lubricating composition, as demonstrated by the measured MRV performance at temperatures as low as about -40°C. In other methods or embodiments, the use of a polymer additive as described in the present disclosure for achieving a passing MRV pumpability according to ASTM D4684 is described herein.

[0009] The following term definitions are provided to clarify the meaning of certain terms as used herein.

[0010] The terms "oil composition", "lubricating composition", "lubricating oil composition", "lubricating oil", "lubricant composition", "lubricating composition", "fully formulated lubricant composition", "lubricant", "crankcase oil", "crankcase lubricant", "engine oil", "engine lubricant", "motor oil", and "motor lubricant" are considered to be fully interchangeable synonymous terms and refer to a finished lubricating product that contains a large amount of base oil plus a small amount of additive composition.

[0011] As used herein, the terms "additive package", "additive concentrate", "additive composition", "engine oil additive package", "engine oil additive concentrate", "crankcase additive package", "crankcase additive concentrate", "motor oil additive package", "motor oil concentrate" are considered to be fully interchangeable synonymous terms and refer to the portion of a lubricating oil composition that excludes the large amount of base oil feedstock mixture. The additive package may or may not include a viscosity index improver or a pour point depressant.

[0012] The term "overbased" relates to metal salts, such as sulfonates, carboxylates, salicylates, and / or phenates, in which the metal content exceeds the stoichiometric amount. Such salts may have a conversion level of greater than 100% (i.e., they may contain more than 100% of the theoretical amount of metal required to convert the acid to its "normal", "neutral" salt). The expression "metal ratio" is commonly abbreviated as MR and is used to represent the ratio of the total chemical equivalents of metal in an overbased salt to the chemical equivalents of metal in the neutral salt, based on known chemical reactivity and stoichiometry. In a normal or neutral salt, the metal ratio is one, while in an overbased salt, the MR is greater than one. They are commonly referred to as overbased, superbased, or hyperbased salts and may be salts of organic sulfuric acids, carboxylic acids, salicylic acids, and / or phenols.

[0013] As used herein, the terms "hydrocarbyl substituent" or "hydrocarbyl group" are used in their ordinary meaning, 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 predominantly having hydrocarbon character. Each hydrocarbyl group is independently selected from hydrocarbon substituents and substituted hydrocarbon substituents containing one or more halogen groups, hydroxy groups, alkoxy groups, mercapto groups, nitro groups, nitroso groups, amino groups, pyridyl groups, furyl groups, imidazolyl groups, oxygen, and nitrogen, and in which there are no more than two non-hydrocarbon substituents for every ten carbon atoms in the hydrocarbyl group.

[0014] As used herein, the term "alkylene substituent" or "alkylene group" is used in its ordinary meaning, which is well known to those skilled in the art. Specifically, it refers to a group that is directly attached to the remainder of the molecule at two positions in the molecule through carbon atoms and that predominantly has a hydrocarbon character. Each alkylene group is independently selected from divalent hydrocarbon substituents and substituted divalent hydrocarbon substituents containing: halogen groups, alkyl groups, aryl groups, alkaryl groups, aralkyl groups, hydroxyl groups, alkoxy groups, mercapto groups, nitro groups, nitroso groups, amino groups, pyridyl groups, furyl groups, imidazolyl groups, oxygen, and nitrogen, and wherein there are no more than two non-hydrocarbon substituents per ten carbon atoms in the alkylene group.

[0015] Unless otherwise expressly stated, as used herein, the term "percent by weight" means the percentage of the component in the weight of the entire composition.

[0016] The terms "soluble", "oil-soluble", or "dispersible" as used herein may but do not necessarily mean that the compound or additive is soluble, dissolvable, miscible, or capable of being suspended in oil in all proportions. However, the foregoing terms do mean that they are, for example, soluble, suspendable, dissolvable, or stably dispersible in oil to an extent sufficient to perform their intended function in an environment employing oil. Additionally, if desired, the incorporation of other additives may also permit the incorporation of higher levels of a particular additive.

[0017] The term "TBN" as used herein is used to denote the total base number in mg KOH / g as measured by the method of ASTM D2896 or ASTM D4739 or DIN 51639-1.

[0018] The term "alkyl" as used herein refers to straight-chain, branched-chain, cyclic, and / or substituted saturated chain moieties having from about 1 to about 100 carbon atoms.

[0019] The term "alkenyl" as used herein refers to straight-chain, branched-chain, cyclic, and / or substituted unsaturated chain moieties having from about 3 to about 10 carbon atoms.

[0020] The term "aryl" as used herein refers to monocyclic and polycyclic aromatic compounds, which may include alkyl, alkenyl, alkaryl, amino, hydroxyl, alkoxy, halogen substituents, and / or heteroatoms, including but not limited to nitrogen, oxygen, and sulfur.

[0021] The lubricants, combinations of components or individual components of this specification may be suitable for use in various types of internal combustion engines. Suitable engine types may include, but are not limited to, heavy-duty diesel engines, passenger vehicles, light-duty diesel engines, medium-speed diesel engines or marine engines. The internal combustion engine may be a diesel fuel engine, a gasoline fuel engine, a natural gas fuel engine, a biofuel engine, a hybrid diesel / biofuel engine, a hybrid gasoline / biofuel engine, an alcohol fuel engine, a hybrid gasoline / alcohol fuel engine, a compressed natural gas (CNG) fuel engine or a mixture thereof. The diesel engine may be a compression ignition engine. The gasoline engine may be a spark ignition engine. The internal combustion engine may also be used in combination with a power supply or a battery power source. An engine so constructed is commonly referred to as a hybrid engine. The internal combustion engine may be a two-stroke, four-stroke or rotary engine. Suitable internal combustion engines include marine diesel engines (such as inland marine), aircraft piston engines, low-load diesel engines and motorcycle, automobile, locomotive and truck engines.

[0022] The internal combustion engine may contain components of one or more of aluminum alloy, lead, tin, copper, cast iron, magnesium, ceramics, stainless steel, composites and / or mixtures thereof. The components may be coated with, for example, a diamond-like carbon coating, a lubricating coating, a phosphorus-containing coating, a molybdenum-containing coating, a graphite coating, a nanoparticle-containing coating and / or mixtures thereof. The aluminum alloy may include aluminum silicate, alumina or other ceramic materials. In one embodiment, the aluminum alloy is an aluminum silicate surface. As used herein, the term "aluminum alloy" is intended to be synonymous with "aluminum composite material" and describes a component or surface containing aluminum and another component that is mixed or reacted with each other at the microscopic or near-microscopic level, regardless of its specific structure. This will include any conventional alloy having a composite or alloy-like structure with a metal other than aluminum and having a non-metallic element or compound (such as a ceramic-like material).

[0023] Regardless of the sulfur, phosphorus, or sulfate ash (ASTM D-874) content, the lubricating oil composition for internal combustion engines can be suitable for any engine lubricant. The sulfur content of the engine oil lubricant can be about 1 wt% or less, or about 0.8 wt% or less, or about 0.5 wt% or less, or about 0.3 wt% or less, or about 0.2 wt% or less. In one embodiment, the sulfur content can be in the range of about 0.001 wt% to about 0.5 wt%, or about 0.01 wt% to about 0.3 wt%. The phosphorus content can be about 0.2 wt% or less, or about 0.1 wt% or less, or about 0.085 wt% or less, or about 0.08 wt% or less, or even about 0.06 wt% or less, about 0.055 wt% or less, or about 0.05 wt% or less. In one example, the phosphorus content can be about 50 ppm to about 1000 ppm, or about 325 ppm to about 850 ppm. The total sulfated ash content can be about 2 wt% or less, or about 1.5 wt% or less, or about 1.1 wt% or less, or about 1 wt% or less, or about 0.8 wt% or less, or about 0.5 wt% or less. In one example, the sulfate ash content can be from about 0.05 wt% to about 0.9 wt%, or from about 0.1 wt% or about 0.2 wt% to about 0.45 wt%. In another example, the sulfur content can be about 0.4 wt% or less, the phosphorus content can be about 0.08 wt% or less, and the sulfate ash is about 1 wt% or less. In yet another example, the sulfur content can be about 0.3 wt% or less, the phosphorus content is about 0.05 wt% or less, and the sulfate ash can be about 0.8 wt% or less.

[0024] In one embodiment, the lubricating oil composition is an engine oil, wherein the lubricating oil composition can have (i) a sulfur content of about 0.5 wt% or less, (ii) a phosphorus content of about 0.1 wt% or less, and (iii) a sulfate ash content of about 1.5 wt% or less.

[0025] In one embodiment, the lubricating oil composition is suitable for 2-stroke or 4-stroke marine diesel internal combustion engines. In one embodiment, the marine diesel internal combustion engine is a 2-stroke engine. In some embodiments, the lubricating oil composition is not suitable for 2-stroke or 4-stroke marine diesel internal combustion engines for one or more reasons, including but not limited to the high sulfur content of the fuel used to power the marine engine and the high TBN required for marine-appropriate engine oils (e.g., above about 40 TBN in marine-appropriate engine oils).

[0026] In some embodiments, the lubricating oil composition is suitable for engines powered by low-sulfur fuels (such as fuels containing about 1 to about 5% sulfur). Highway vehicle fuel contains about 15 ppm sulfur (or about 0.0015% sulfur).

[0027] Low-speed diesel engines generally refer to marine engines, medium-speed diesel engines generally refer to railway locomotives, and high-speed diesel engines generally refer to highway vehicles. The lubricant composition can be applicable to only one or all of these types.

[0028] In addition, the lubricants of this specification can be suitable for meeting one or more industrial specification requirements, such as ILSAC GF-3, GF-4, GF-5, GF-6, PC-11, CF, CF-4, CH-4, CK-4, FA-4, CJ-4, CI-4Plus, CI-4, API SG, SJ, SL, SM, SN, SN PLUS, ACEA A1 / B1, A2 / B2, A3 / B3, A3 / B4, A5 / B5, C1, C2, C3, C4, C5, E4 / E6 / E7 / E9, Euro 5 / 6, JASO DL-1, Low SAPS, Mid SAPS, or original equipment manufacturer specifications, such as Dexos1 TM , Dexos2 TM , MB-Approval 229.1, 229.3, 229.5, 229.51 / 229.31, 229.52, 229.6, 229.71, 226.5, 226.51, 228.0 / .1, 228.2 / .3, 228.31, 228.5, 228.51, 228.61, VW 501.01, 502.00, 503.00 / 503.01, 504.00, 505.00, 505.01, 506.00 / 506.01, 507.00, 508.00, 509.00, 508.88, 509.99, BMW Longlife-01, Longlife-01FE, Longlife-04, Longlife-12FE, Longlife-14FE+, Longlife-17FE+, Porsche A40, C30, Peugeot Automobiles B71 2290, B71 2294, B71 2295, B71 2296, B71 2297, B712300, B71 2302, B71 2312, B71 2007, B71 2008, Renault RN0700, RN0710, RN0720, Ford WSS-M2C153-H, WSS-M2C930-A, WSS-M2C945-A, WSS-M2C913A, WSS-M2C913-B, WSS-M2C913-C, WSS-M2C913-D, WSS-M2C948-B, WSS-M2C948-A, GM 6094-M, Chrysler MS-6395, Fiat 9.55535G1, G2, M2, N1, N2, Z2, S1, S2, S3, S4, T2, DS1, DSX, GH2, GS1, GSX, CR1, Jaguar Land Rover STJLR.03.5003, STJLR.03.5004, STJLR.03.5005, STJLR.03.5006, STJLR.03.5007, STJLR.51.5122 or any past or future PCMO or HDD specifications not mentioned herein. In some embodiments, for passenger car motor oil (PCMO) applications, the amount of phosphorus in the finished fluid is 1000 ppm or less, or 900 ppm or less, or 800 ppm or less.

[0029] Other hardware may not be suitable for the disclosed lubricants. "Functional fluid" is a term encompassing a variety of fluids, including but not limited to tractor hydraulic fluids, power transmission fluids including automatic transmission fluids, continuously variable transmission fluids, and manual transmission fluids, hydraulic fluids including tractor hydraulic fluids, some gear oils, power steering fluids, fluids for wind turbines, compressors, some industrial fluids, and fluids related to driveline components. It should be noted that within each of these fluids, for example, within an automatic transmission fluid, there are various different types of fluids because various transmissions have different designs, which results in a need for fluids with significantly different functional characteristics. In contrast to this is the term "lubricating fluid", which is not used to generate or transmit power.

[0030] Regarding tractor hydraulic fluids, for example, these fluids are general-purpose products for all lubricant applications in tractors other than lubricating the engine. These lubrication applications can include the lubrication of gearboxes, power take-offs and clutches, rear axles, reduction gears, wet brakes, and hydraulic accessories.

[0031] When the functional fluid is an automatic transmission fluid, the automatic transmission fluid must have sufficient friction for the clutch plates to transfer power. However, when the fluid gets hot during operation, the friction coefficient of the fluid has a tendency to decrease due to the temperature effect. Importantly, tractor hydraulic fluid or automatic transmission fluid will maintain its high friction coefficient at elevated temperatures, otherwise the braking system or the automatic transmission may fail. This is not a function of engine oil.

[0032] Tractor fluids, such as Super Tractor Universal Oil (STUO) or Universal Tractor Transmission Oil (UTTO), can combine the performance of engine oil with that of transmissions, differentials, final drive planetary gears, wet brakes, and hydraulics. Although many of the additives used to formulate UTTO or STUO fluids are functionally similar, if not added properly, these additives can have harmful effects. For example, some anti-wear and extreme pressure additives used in engine oil can be highly corrosive to copper components in hydraulic pumps. Detergents and dispersants used for gasoline or diesel engine performance can be detrimental to wet brake performance. Friction modifiers specifically designed to eliminate wet brake noise may lack the thermal stability required for engine oil performance. Each of these fluids, whether functional, tractor, or lubricating, is designed to meet specific and stringent manufacturer requirements.

[0033] The present disclosure provides novel lubricating oil blends formulated to be used as automotive crankcase lubricants. The present disclosure provides novel lubricating oil blends formulated to be used as 2T and / or 4T motorcycle crankcase lubricants. Embodiments of the present disclosure can provide lubricating oils suitable for crankcase applications and having improvements in the following characteristics: air intake, alcohol fuel compatibility, antioxidant properties, anti-wear performance, biofuel compatibility, defoaming characteristics, friction reduction, fuel economy, pre-ignition prevention, rust prevention, sludge and / or soot dispersibility, piston cleanliness, deposit formation, and water tolerance.

[0034] The engine oils of the present disclosure can be formulated by adding one or more additives (as described in detail below) to a suitable base oil formulation. The additives can be combined with the base oil in the form of an additive package (or concentrate) or alternatively, can be combined individually with the base oil (or a mixture of both). Based on the additives added and their respective proportions, the fully formulated engine oils can exhibit improved performance characteristics.

[0035] As used herein, polymerizable reactants and / or monomers that form a polymer or copolymer are described. Unless the context dictates otherwise, a polymer generally refers to a polymer of one type of monomer, while a copolymer refers to a polymer of more than one type of monomer. A reactant or monomer generally refers to a compound within a reaction mixture prior to polymerization, while a monomer unit or (alternatively) repeating unit refers to a reactant or monomer that has polymerized within a polymer chain. The various monomers herein typically polymerize randomly within the backbone as monomer units or repeating units. If the discussion refers to a reactant or monomer, then the resulting monomer unit or its repeating unit derived therefrom in the polymer is also implied. Similarly, if the discussion refers to a monomer unit or repeating unit, then the reactant mixture or monomer mixture used to form the polymer and the associated monomer or repeating unit therein are also implied.

[0036] Other details and advantages of the present disclosure will be set forth in part in the following description, and / or may be learned by practice of the present disclosure. The details and advantages of the present disclosure may be realized and obtained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure as claimed. Detailed Description

[0037] Engine or crankcase lubricant compositions are typically used in vehicles containing spark ignition and compression ignition engines to provide reduced friction and other benefits. Such engines can be used in automotive, truck, and / or train applications to name just a few, and can operate on fuels including but not limited to gasoline, diesel, alcohol, biofuels, compressed natural gas, etc. These engines can include hybrid electric engines that include an internal combustion engine and an electric or battery power source; and / or advanced hybrid or internal combustion engines that include an engine auto-stop function when the vehicle is stationary.

[0038] The present disclosure describes unique blends of polymer additives and lubricating compositions comprising such polymer blends that are suitable for use as engine lubricants, such as automotive crankcase lubricants, that in some cases can meet or exceed the ILSAC GF-6 and / or API CK lubricant standards and provide robust functionality at temperatures as low as about -40°C, and in particular meet or exceed the pumpability performance of the industrial MRV test (ASTM D4684). Other lubricating compositions that are expected to operate at extreme low temperatures, such as but not limited to automotive transmissions or gearboxes, industrial or personal machines, metalworking, turbines, gear oils, etc., may also benefit from the polymer surfactants of the present disclosure.

[0039] In one aspect, the present disclosure provides a blend of at least two different polymer additives in a finished lubricating composition at a low treatment rate, such as a treatment rate of about 1 wt% or less (or about 0.8 wt% or less, about 0.6 wt% or less, or about 0.5 wt% or higher), and provides acceptable low-temperature pumpability as measured by the MRV test from ASTM D4684. Specifically, the finished lubricating composition of the present disclosure comprises a blend of one or more poly(meth)acrylate copolymers and one or more modified styrene-maleic anhydride copolymers in amounts and ratios effective to achieve passing MRV parameters, including an MRV viscosity of less than 60,000 cP at the test temperature and an MRV yield stress of less than 35, depending on the oil grade.

[0040] Modified styrene-maleic anhydride copolymer : In one aspect, the first copolymer of the polymer blend that achieves good low-temperature pumpability comprises a modified styrene-maleic anhydride copolymer, and in particular an esterified styrene-maleic anhydride copolymer that is partially or fully esterified with one or more long-chain straight-chain or branched-chain alcohols having an alkyl chain length of 10 to 24 carbons. In some methods, the copolymer has repeating units of formula I derived from styrene residues and repeating units of formula IIa and / or IIb derived from fully or partially esterified maleic anhydride residues, where R is independently a C12 to C18 straight-chain or branched-chain alkyl group:

[0041]

[0042] In some methods, the modified styrene-maleic anhydride copolymer has a polymer backbone of a styrene-maleic anhydride copolymer that comprises from about 30 wt% to about 70 wt% of repeating units derived from styrene, and in other methods from about 40 wt% to about 60 wt% of units derived from styrene.

[0043] The modified styrene-maleic anhydride copolymer can be prepared by first polymerizing styrene and maleic anhydride (or maleic acid) under conditions suitable for forming the copolymer. The polymerization can be continued until a desired molecular weight is reached, such as a number-average molecular weight of about 10,000 to about 100,000, and in other methods about 30,000 to about 50,000. The polymer can also have a polydispersity index ranging from about 4 or less, about 3 or less, or about 2.5 or less to about 2 or greater, or about 2.5 or greater. As used herein, the polydispersity index is the weight-average molecular weight divided by the number-average molecular weight. In some methods, the polymerization can be initiated by a suitable catalyst, such as a free-radical initiator, including peroxide catalysts such as benzoyl peroxide, butyl peroxide, or di-tert-butyl peroxide. If desired, a solvent or diluent can be used in the polymerization.

[0044] The styrene-maleic anhydride copolymer is then esterified with a long-chain alcohol, and in some methods, with a mixture of long-chain alcohols. Generally, suitable alcohols are straight-chain or branched-chain alcohols having 10 or more carbons, such as straight-chain or branched-chain alcohols having 18 to 30 carbons, in other methods, straight-chain or branched-chain alcohols having 20 to 28 carbons, and in still other methods, straight-chain or branched-chain alcohols having 12 to 20 carbons. Generally, for each mole of maleic anhydride in the polymer, about two moles of alcohol are used for esterification. Esterification is well known to those skilled in the art, and an exemplary reaction can be carried out at a temperature of about 160 °C to 200 °C for about 3 hours to about 6 hours. An esterification catalyst, such as methanesulfonic acid or dodecylbenzenesulfonic acid, can be added. The reaction can also be carried out in the presence of a suitable solvent or diluent, such as a heavy aromatic solvent. Although maleic anhydride is usually esterified after polymerization, it can also be esterified before polymerization. In some methods, the copolymer is at least about 90% esterified.

[0045] The molecular weight of any of the examples herein can be measured using an instrument such as a gel permeation chromatography (GPC) instrument obtained from Waters, and the data can be 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). The GPC operating conditions can include a guard column, 4 Agilent PLgel columns (length 300 × 7.5 mm; particle size 5 μ, and pore size range 100- ), the column temperature is about 40 °C. Unstabilized HPLC grade tetrahydrofuran (THF) can be used as the solvent, and the flow rate is 1.0 mL / min. The GPC instrument can be calibrated with commercially available polystyrene (PS) standards having a narrow molecular weight distribution in the range of 500 g / mol to 380,000 g / mol. For samples with a mass less than 500 g / mol, the calibration curve can be extrapolated. The samples and PS standards can be dissolved in THF and prepared at a concentration of 0.1 to 0.5 wt.%, and 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, W.W. Yau, J.J. Kirkland, and D.D. Bly, “Modern Size Exclusion Liquid Chromatography”, John Wiley and Sons, New York, 1979, which is also incorporated herein by reference.

[0046] Poly(meth)acrylate copolymer:On the other hand, the second copolymer of the polymer blend that achieves good low-temperature pumpability includes one or more poly(meth)acrylate copolymers, and in particular copolymers derived from linear or branched alkyl esters of (meth)acrylic acid. Suitable (meth)acrylic acid alkyl ester reactants can have an alkyl chain length of 1 to 20 carbons. As used herein, “(meth)acrylate” refers to both methacrylate and / or acrylate monomers or monomer units (or mixtures). Generally, the number-average molecular weight of the poly(meth)acrylate polymer is about 20,000 or higher, and the polydispersity index is about 3 or lower, or 2 or lower.

[0047] The poly(meth)acrylate copolymers suitable as polymer additives herein can be prepared by any suitable conventional or controlled radical polymerization techniques. Examples include conventional radical polymerization (FRP), reversible addition-fragmentation chain transfer (RAFT), atom transfer radical polymerization (ATRP), and other controlled types of polymerization known in the art. The polymerization procedures are known to those skilled in the art and include the use of, for example, common polymerization initiators (such as Vazo TM 67 (2,2’-azobis(2-methylbutyronitrile)), a chain transfer agent (such as dodecyl mercaptan) if conventional FRP is used, or a RAFT agent (such as 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, etc.) if RAFT polymerization is used. Depending on the specific application requirements, other initiators, chain transfer agents, RAFT agents, ATRP catalysts, and initiator systems can be used as known in the art.

[0048] In one method, the copolymers herein include the reaction product in the form of a linear random polymer of a selected amount of long-chain, medium-chain, and short-chain (meth)acrylic acid alkyl ester monomers. In some methods, the short-chain (meth)acrylic acid alkyl ester monomer (or monomer unit) has an alkyl chain length of 1 to 4 carbons, the medium-chain (meth)acrylic acid alkyl ester monomer (or monomer unit) has an alkyl chain length of 6 to 16 carbons, and the long-chain (meth)acrylic acid alkyl ester monomer (or monomer unit) has an alkyl chain length of 16 to 20 carbons. These monomers and monomer units are further described below and include linear and / or branched alkyls in the chain.

[0049] In one embodiment, the poly(meth)acrylate copolymer can include short-chain (meth)acrylate units derived from methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and / or butyl (meth)acrylate. Preferably, the short-chain units are derived from methyl (meth)acrylate.

[0050] In another embodiment, the poly(meth)acrylate copolymer may further include mid-chain (meth)acrylate units derived from (meth)acrylate monomers having an alkyl group with 6 to 16 carbons and preferably 12 to 16 carbons or a total alkyl chain length (including any branches). Exemplary mid-chain (meth)acrylate alkyl esters may be LMA or lauryl (meth)acrylate, which may include blends of (meth)acrylate monomers or monomer units having an alkyl chain length in the range of C12 to C16, and in particular alkyl chains of 12, 14, and 16 carbons in the blend, where the C12 (meth)acrylate alkyl ester is in the majority.

[0051] In another embodiment, the poly(meth)acrylate copolymer may further include long-chain (meth)acrylate alkyl ester units derived from (meth)acrylate monomers having an alkyl group with 16 to 20 carbons and preferably 18 to 20 carbons or a total alkyl chain length (including any branches). Exemplary mid-chain (meth)acrylate alkyl esters may be CEMA or cetyl-eicosyl (meth)acrylate, which may include blends of (meth)acrylate monomers or monomer units having an alkyl chain length in the range of C16 to C20, and in particular alkyl chains of 16, 18, and 20 carbons. For example, the CEMA monomer blend or monomer unit blend may include a majority of C16 and C18 chains and a minor amount of C20 chains.

[0052] The poly(meth)acrylate copolymers herein may also include other optional monomers and monomer units, including, for example, hydroxyalkyl (meth)acrylates and / or various dispersant monomers and monomer units. The poly(meth)acrylate copolymers herein may also optionally be functionalized with one or more dispersant monomers or monomer units. In one method, the dispersant monomer or monomer unit may be a nitrogen-containing monomer or its unit. If used, these monomers can impart polymer dispersant functionality. In some methods, the nitrogen-containing monomer may be a (meth)acrylic acid monomer, such as a methacrylate, methacrylamide, etc. In some methods, the connection of the nitrogen-containing moiety to the acrylic moiety can be through a nitrogen atom or an oxygen atom, in which case the nitrogen of the monomer will be located at other positions of the monomer. The nitrogen-containing monomer can also be other than a (meth)acrylic acid monomer, such as a vinyl-substituted azacycle monomer and a vinyl-substituted amine. Nitrogen-containing monomers include, for example, those in US 6,331,603. Other suitable dispersant monomers include, but are not limited to, dialkylaminoalkyl acrylates, (meth)acrylic acid dialkylaminoalkyl esters, dialkylaminoalkylacrylamides, dialkylaminoalkylmethacrylamides, N-tert-alkylacrylamides, and N-tert-alkylmethacrylamides, where the alkyl or aminoalkyl may independently contain 1 to 8 carbon atoms. For example, the dispersant monomer can be dimethylaminoethyl (meth)acrylate. The nitrogen-containing monomer can be, for example, tert-butylacrylamide, dimethylaminopropyl (meth)acrylamide, dimethylaminoethyl methacrylamide, N-vinylpyrrolidone, N-vinylimidazole, or N-vinylcaprolactam. It can also be a (meth)acrylamide based on any aromatic amine disclosed in WO2005 / 087821, including 4-phenylazoaniline, 4-aminodiphenylamine, 2-aminobenzimidazole, 3-nitroaniline, 4-(4-nitrophenylazo)aniline, N-(4-amino-5-methoxy-2-methyl-phenyl)-benzamide, N-(4-amino-2,5-dimethoxy-phenyl)-benzamide, N-(4-amino-2,5-diethoxy-phenyl)-benzamide, N-(4-amino-phenyl)-benzamide, 4-amino-2-hydroxy-benzoic acid.

[0053] The PMA copolymers of the present disclosure are generally synthesized to have a number average molecular weight of 20,000 or higher, and in other methods, about 30,000 or higher. Suitable ranges of the number average molecular weight include from about 10,000 to about 100,000, in other methods from about 20,000 to about 80,000, and in still other methods from about 30,000 to about 50,000. Such copolymers herein generally have a polydispersity index in the range of about 1 to about 3, in other methods from about 1.2 to about 3, in still other methods from about 1.2 to about 2, and in still other methods from about 2 to about 3.

[0054] The poly(meth)acrylate copolymer can be prepared by any suitable conventional or controlled free radical polymerization technique. Examples include conventional free radical polymerization (FRP), reversible addition-fragmentation chain transfer (RAFT), atom transfer radical polymerization (ATRP), and other controlled types of polymerization known in the art. The polymerization procedures are known to those skilled in the art and include the use of, for example, common polymerization initiators (such as Vazo TM 67 (2,2'-azobis(2-methylbutyronitrile)), and if conventional FRP is used, a chain transfer agent such as dodecyl mercaptan, or if RAFT polymerization is used, a RAFT agent such as 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, etc. Depending on the specific application requirements, other initiators, chain transfer agents, RAFT agents, ATRP catalysts, and initiator systems can be used as known in the art.

[0055] Polymer blend : On the other hand, it has surprisingly been found that only the blend of the modified styrene-maleic anhydride copolymer and the poly(meth)acrylate copolymer herein achieves improved MRV performance, since neither polymer alone can achieve effective low-temperature performance. In one method, based on the total weight of the two copolymers in the blend, the blend contains at least about 40 wt% of the modified styrene-maleic anhydride copolymer, and in some methods contains up to about 60 wt% of the modified styrene-maleic anhydride copolymer. The weight percentages of the copolymers include the active polymer and any solvent / diluent. The amount of the active polymer of the modified styrene-maleic anhydride copolymer ranges from about 30 wt% to about 50 wt% of this component. In other methods, it has also surprisingly been found that a specific ratio of the two copolymers in the blend achieves the desired results. For example and in some methods, the ratio of the modified styrene-maleic anhydride copolymer to the poly(meth)acrylate copolymer that effectively achieves good MRV performance is from about 1:2 to about 1:0.7.

[0056] Lubricating oil composition : The polymer additive blend of the two polymers described herein can be combined with a major amount of one or more base oils having lubricating viscosity (described below) and one or more other optional additives to prepare a lubricating oil composition having robust low-temperature viscosity characteristics including the MRV characteristics passed. In a method, based on the total weight of the lubricant composition, the lubricating oil composition herein can contain a polymer blend in the range of from about 0.5 wt% or more to about 1 wt% or less, and in other methods, an amount of the polymer blend of from about 0.5 wt% to about 0.6 wt%.

[0057] Base oil: The base oil used in the lubricating oil composition herein may be optionally any one of the base oils in Groups I-V as specified in the "American Petroleum Institute (API) Base Oil Interchangeability Guidelines". The five groups of base oils are as follows:

[0058] Table 1 :

[0059]

[0060] Groups I, II, and III are mineral oil processing feedstocks. Group IV base oils contain true synthetic molecular species, which are prepared by the polymerization of olefinically unsaturated hydrocarbons. Many Group V base oils are also true synthetic products and may include diesters, polyol esters, polyalkylene glycols, alkylated aromatics, polyphosphates, polyethylene ethers, and / or polyphenylene ethers, etc., but may also be naturally occurring oils such as vegetable oils. It should be noted that although Group III base oils are derived from mineral oils, the rigorous processing these fluids undergo results in their physical properties being very similar to some true synthetic oils such as PAO. Therefore, oils derived from Group III base oils can be referred to as synthetic fluids in the industry. Group II+ may include Group II with a high viscosity index.

[0061] The base oil used in the disclosed lubricating oil composition can be mineral oil, animal oil, vegetable oil, synthetic oil, synthetic oil blend, or a mixture thereof. Suitable oils can be derived from hydrocracked, hydrogenated, hydrorefined, unrefined, refined, and re-refined oils, and mixtures thereof.

[0062] Unrefined oils are those oils derived from natural, mineral, or synthetic sources without or with very little further purification treatment. Refined oils are similar to unrefined oils, except that they have been treated with one or more purification steps, which may result in the improvement of one or more properties. Examples of suitable purification techniques 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 can also be called white oils. In some embodiments, the lubricating oil composition does not contain edible oils or white oils.

[0063] Re-refined oils are also called recycled oils or reprocessed oils. Similar to refined oils, these oils are obtained using the same or similar processing. Usually, these oils are further processed by techniques aimed at removing waste additives and oil decomposition products.

[0064] Mineral oils can include oils obtained by drilling or oils from plants and animals or any mixtures thereof. For example, such oils can include, but are not limited to, castor oil, lard, olive oil, peanut oil, corn oil, soybean oil, and linseed oil, as well as mineral lubricating oils such as liquid petroleum and solvent-treated or acid-treated paraffinic, naphthenic, or mixed paraffinic-naphthenic type mineral lubricating oils. If desired, such oils can be partially or fully hydrogenated. Oils derived from coal or shale can also be suitable.

[0065] Useful synthetic lubricating oils can include hydrocarbon oils such as polymerized, oligomerized, or copolymerized olefins (e.g., polybutene, polypropylene, propylene-isobutylene copolymer); poly(1-hexene), poly(1-octene), trimers or oligomers of 1-decene such as poly(1-decene), such materials are commonly 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 polyphenyl); diphenylalkanes, alkylated diphenylalkanes, alkylated diphenyl ethers, and alkylated diphenyl sulfides and their derivatives, analogs, and homologs or mixtures thereof. Poly-α-olefins are typically hydrogenated materials.

[0066] Other synthetic lubricating oils include polyol esters containing phosphoric acid, diesters, liquid esters (e.g., tolyl phosphate, trioctyl phosphate, and diethyl decylphosphonate), or polytetrahydrofuran. Synthetic oils can be produced by the Fischer-Tropsch reaction and can typically be hydroisomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, the oil can be prepared by a Fischer-Tropsch gas-liquid synthesis process as well as other gas-liquid oils.

[0067] The major amount of base oil contained in the lubricating composition can be selected from Group I, Group II, Group III, Group IV, Group V, and combinations of two or more of the foregoing, and wherein the major amount of base oil is different from the base oil produced by providing additive components or viscosity index improvers in the composition. In another embodiment, the major amount of base oil contained in the lubricating composition can be selected from Group II, Group III, Group IV, Group V, and combinations of two or more of the foregoing, and wherein the major amount of base oil is different from the base oil produced by providing additive components or viscosity index improvers in the composition.

[0068] The amount of oil having lubricating viscosity can be the balance remaining after subtracting from 100% by weight the total amount of performance additives, including viscosity index improvers and / or pour point depressants and / or other top treatment additives. For example, the oil having lubricating viscosity that can be present in the finished fluid can be the major amount, such as 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, or greater than about 90% by weight.

[0069] Optional additive : The engine oil or lubricating oil compositions herein may also optionally include a variety of optional additives as needed to meet performance criteria. Those optional additives are described in the following paragraphs.

[0070] Antioxidant : The lubricating oil compositions herein may also optionally contain one or more antioxidants. Antioxidant compounds are known and include, for example, phenolates, phenol sulfides, sulfurized olefins, sulfurized terpenes, sulfurized 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 can be used alone or in combination.

[0071] The hindered phenol antioxidant may contain secondary butyl and / or tertiary butyl as the sterically hindered group. The phenolic group may be further substituted with a hydrocarbon group and / or a bridging group attached 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 can be an ester and can include, for example, Irganox TM L-135 or an 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 can be an ester and can include Ethanox TM 4716.

[0072] Available antioxidants can include diarylamines and high molecular weight phenols. In one embodiment, the lubricating oil composition can contain a mixture of diarylamines and high molecular weight phenols such that each antioxidant can be present in an amount sufficient to provide up to about 5 wt% based on the final weight of the lubricating oil composition. In one example, based on the final weight of the lubricating oil composition, the antioxidant can be a mixture of about 0.3 to about 1.5 wt% diarylamine and about 0.4 to about 2.5 wt% high molecular weight phenol.

[0073] 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 example, hexadecene, heptadecene, octadecene, nonadecene, eicosene, or mixtures thereof, and their dimers, trimers, and tetramers 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).

[0074] Another class of sulfurized olefins includes sulfurized fatty acids and their esters. Fatty acids are typically obtained from vegetable or animal oils and typically contain 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. Generally, the fatty acids are obtained from lard, pine 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 alpha - olefins).

[0075] In another alternative embodiment, in addition to the phenolic and / or amine antioxidants discussed above, the antioxidant composition further contains a molybdenum - containing antioxidant. When using a combination of these three antioxidants, preferably, the ratio of the phenolic antioxidant to the amine antioxidant to the molybdenum - containing antioxidant is (0 to 2):(0 to 2):(0 to 1).

[0076] 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%.

[0077] Antiwear agent: The lubricating oil composition herein may also optionally contain one or more antiwear agents. Examples of suitable antiwear agents include, but are not limited to, metal thiophosphates; metal dialkyldithiophosphates; phosphate esters or their salts; phosphate esters; phosphite esters; phosphorus-containing carboxylic acid esters, ethers or amides; sulfurized olefins; compounds containing thiocarbamates, including thiocarbamates, alkylene-coupled thiocarbamates and bis(S-alkyldithiocarbamoyl) disulfides; and mixtures thereof. A suitable antiwear agent may be molybdenum dithiocarbamate. Phosphorus-containing antiwear agents are more fully described in European Patent 612 839. The metal in the dialkyldithiophosphate may be an alkali metal, alkaline earth metal, aluminum, lead, tin, molybdenum, manganese, nickel, copper, titanium or zinc. A suitable antiwear agent may be zinc dialkyldithiophosphate.

[0078] Another embodiment of suitable antiwear agents includes titanium compounds, tartrate esters, tartramides, oil-soluble amine salts of phosphorus compounds, sulfurized olefins, phosphite esters (such as dibutyl phosphite), phosphonate esters, compounds containing thiocarbamates (such as thiocarbamates, thiocarbamate amides, thiocarbamate ethers, alkylene-coupled thiocarbamates and bis(S-alkyldithiocarbamoyl) disulfides). The tartrate ester or tartramide may contain alkyl ester groups, where the total number of carbon atoms in the alkyl group may be at least 8. In one embodiment, the antiwear agent may include citrate esters.

[0079] The antiwear agent 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.

[0080] Boron-containing compound : The lubricating oil composition herein may optionally contain one or more boron-containing compounds. Examples of boron-containing compounds include borate esters, boronated fatty amines, boronated epoxides, boronated detergents and boronated dispersants, such as boronated succinimide dispersants, as disclosed in U.S. Patent No. 5,883,057. The boron-containing compound, if present, may be used in an amount sufficient to provide up to about 8 wt%, about 0.01 wt% to about 7 wt%, about 0.05 wt% to about 5 wt%, or about 0.1 wt% to about 3 wt% of the lubricating oil composition.

[0081] Detergent:The lubricating oil composition may optionally further comprise one or more neutral, low-alkalinity or high-alkalinity detergents and mixtures thereof. Suitable detergent bases include benzoates, sulfur-containing benzoates, sulfonates, calixates, salicylates, saligenins, carboxylic acids, phosphoric acids, monothiophosphoric acids and / or dithiophosphoric acids, alkylphenols, sulfur-coupled alkylphenol compounds or methylene-bridged phenols. Suitable detergents and methods for their preparation are described in more detail in a number of patent publications, including US 7,732,390 and the references cited therein.

[0082] The detergent base may be salified with, for example but not limited to, the following alkali or alkaline earth metals: calcium, magnesium, potassium, sodium, lithium, barium or mixtures thereof. In some embodiments, the detergent is barium-free. In some embodiments, the detergent may contain trace amounts of other metals, such as magnesium or calcium, in an amount of 50 ppm or less, 40 ppm or less, 30 ppm or less, 20 ppm or less, or 10 ppm or less. Suitable detergents may include alkali or alkaline earth metal salts of petroleum sulfonic acids and long-chain mono- or dialkylarylsulfonic acids, wherein the aryl group is benzyl, tolyl and xylyl. Examples of suitable detergents include, but are not limited to: calcium phenate, sulfur-containing calcium phenate, calcium sulfonate, calcium calixarates, calcium salixarates, calcium salicylate, calcium carboxylate, calcium phosphate, calcium monothiophosphate and / or calcium dithiophosphate, calcium alkylphenate, sulfur-coupled calcium alkylphenol compound, methylene-bridged calcium phenol, magnesium phenate, sulfur-containing magnesium phenate, magnesium sulfonate, magnesium calixarates, magnesium salixarates, magnesium salicylate, magnesium carboxylate, magnesium phosphate, magnesium monothiophosphate and / or magnesium dithiophosphate, magnesium alkylphenate, sulfur-coupled magnesium alkylphenol compound, methylene-bridged magnesium phenol, sodium phenate, sulfur-containing sodium phenate, sodium sulfonate, sodium calixarates, sodium salixarates, sodium salicylate, sodium carboxylate, sodium phosphate, sodium monothiophosphate and / or sodium dithiophosphate, sodium alkylphenate, sulfur-coupled sodium alkylphenol compound, or methylene-bridged sodium phenol.

[0083] Overbased detergent additives are well known in the art and may be alkali or alkaline earth metal overbased detergent additives. Such detergent additives can be prepared by reacting a metal oxide or metal hydroxide with a base and carbon dioxide gas. The base is typically an acid, such as the following acids: sulfonic acids substituted with aliphatic groups, carboxylic acids substituted with aliphatic groups or phenols substituted with aliphatic groups.

[0084] The term "overbased" relates to metal salts, such as metal salts of sulfonic acid, carboxylic acid, and phenol, in which the amount of metal present exceeds the stoichiometric amount. Such salts can have a conversion level of more than 100% (i.e., they can contain more than 100% of the theoretical amount of metal required to convert the acid to its "normal," "neutral" salt). The expression "metal ratio" is usually abbreviated as MR, which is used to represent the ratio of the total chemical equivalent of the metal in the overbased salt to the chemical equivalent of the metal in the neutral salt according to known chemical reactivity and stoichiometry. In a normal or neutral salt, the metal ratio is one, while in an overbased salt, the MR is greater than one. They are commonly referred to as overbased, superbasic, or hyperbasic salts and can be salts of organic sulfuric acid, carboxylic acid, or phenol.

[0085] The total base number (TBN) of an overbased detergent in a lubricating oil composition can be about 200 mg KOH / gram or greater, or in other examples, about 250 mg KOH / gram or greater, or about 350 mg KOH / gram or greater, or about 375 mg KOH / gram or greater, or about 400 mg KOH / gram or greater.

[0086] Examples of suitable overbased detergents include, but are not limited to: overbased calcium phenate, overbased sulfur-containing calcium phenate, overbased calcium sulfonate, overbased calixarboxylate calcium, overbased salicylate calcium, overbased calcium carboxylate, overbased calcium phosphate, overbased calcium monothiophosphate and / or dithiophosphate, overbased alkyl calcium phenate, overbased sulfur-coupled alkyl calcium phenate compound, overbased methylene-bridged calcium phenate, overbased magnesium phenate, overbased sulfur-containing magnesium phenate, overbased magnesium sulfonate, overbased calixarboxylate magnesium, overbased salicylate magnesium, overbased magnesium carboxylate, overbased magnesium phosphate, overbased magnesium monothiophosphate and / or dithiophosphate, overbased alkyl magnesium phenate, overbased sulfur-coupled alkyl magnesium phenate compound, or overbased methylene-bridged magnesium phenate.

[0087] The total base number of an overbased calcium phenate detergent is at least about 150 mg KOH / g, at least about 225 mg KOH / g, at least about 225 mg KOH / g to about 400 mg KOH / g, at least about 225 mg KOH / g to about 350 mg KOH / g, or about 230 mg KOH / to about 350 mg KOH / g, all as measured by the method of ASTM D-2896. When such a detergent composition is formed in an inert diluent (such as process oil, usually mineral oil), the total base number reflects the alkalinity of the entire composition, which includes the diluent and any other materials (such as promoters, etc.) that may be contained in the detergent composition.

[0088] The metal-to-substrate ratio of the overbased detergent can be 1.1:1, or 2:1, or 4:1, or 5:1, or 7:1, or 10:1. In some embodiments, the detergent is effective in reducing or preventing rust in an engine. The detergent can be present at about 0 wt% to about 10 wt%, or about 0.1 wt% to about 8 wt%, or about 1 wt% to about 4 wt%, or greater than about 4 wt% to about 8 wt%.

[0089] Dispersant : The lubricating oil composition may optionally further comprise one or more dispersants or mixtures thereof. Dispersants are commonly referred to as ashless dispersants because they do not contain ash-forming metals prior to being mixed in the lubricating oil composition and generally do not contribute any ash when added to a lubricant. Ashless dispersants are characterized by having a polar group attached to a relatively high molecular weight hydrocarbon chain. Typical ashless dispersants include N-substituted long-chain alkenyl succinimides. Examples of N-substituted long-chain alkenyl succinimides include polyisobutylene succinimide, wherein the number average molecular weight of the polyisobutylene substituent, as measured by GPC, is in the range of about 350 to about 50,000 or to about 5,000 or to about 3,000. Succinimide dispersants and their preparation are disclosed, for example, in U.S. Patent No. 7,897,696 or U.S. Patent No. 4,234,435. Polyolefins can be prepared from polymerizable monomers containing about 2 to about 16, or about 2 to about 8, or about 2 to about 6 carbon atoms. Succinimide dispersants are generally imides formed from polyamines, typically poly(ethylene amines).

[0090] Preferred amines are selected from polyamines and hydroxylamines. Examples of polyamines that can be used include, but are not limited to, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), and higher homologues such as pentaethylenehexamine (PEHA), etc.

[0091] Suitable heavy polyamines are mixtures of polyalkylene-polyamines that contain small amounts of lower polyamine oligomers such as TEPA and PEHA (pentaethylenehexamine) but are mainly oligomers having 6 or more nitrogen atoms per molecule, 2 or more primary amines, and a more extensive branching than conventional polyamine mixtures. The heavy polyamines preferably include polyamine oligomers containing 7 or more nitrogen per molecule and having 2 or more primary amines per molecule. The heavy polyamines contain greater than 28 wt.% (e.g., >32 wt.%) total nitrogen and an equivalent weight of primary amine groups of 120 - 160 grams / equivalent.

[0092] Suitable polyamines are commonly referred to as PAM and contain a mixture of ethylene amines, wherein TEPA and pentaethylenehexamine (PEHA) are the major portions of the polyamines, usually less than about 80%.

[0093] Typically, the PAM has a primary amine content of 8.7 - 8.9 milliequivalents per gram (the equivalent weight of each milliequivalent of primary amine is 115 to 112 grams) and a total nitrogen content of about 33 - 34 wt.%. A heavy fraction of PAM oligomers with little to no TEPA and only very small amounts of PEHA but mainly containing oligomers with more than 6 nitrogens and more extensive branching can produce a dispersant with improved dispersibility.

[0094] In one embodiment, the present disclosure further includes at least one polyisobutylene succinimide dispersant derived from polyisobutylene having a number average molecular weight in the range of about 350 to about 50,000 or to about 5,000 or to about 3,000, as determined by GPC. The polyisobutylene succinimide can be used alone or in combination with other dispersants.

[0095] In some embodiments, the polyisobutylene (when included) can have a terminal double bond content greater than 50 mol%, greater than 60 mol%, greater than 70 mol%, greater than 80 mol%, or greater than 90 mol%. Such PIB is also referred to as highly reactive PIB (“HR-PIB”). HR-PIB having a number average molecular weight in the range of about 800 to about 5,000, as determined by GPC, is suitable for the embodiments of the present disclosure. Conventional PIB typically has a terminal double bond content less than 50 mol%, less than 40 mol%, less than 30 mol%, less than 20 mol%, or less than 10 mol%.

[0096] As determined by GPC, HR-PIB having a number average molecular weight in the range of about 900 to about 3,000 can be suitable. Such HR-PIB is commercially available or can be synthesized by polymerizing isobutylene in the presence of a non-chlorinated catalyst such as boron trifluoride, as described in U.S. Patent No. 4,152,499 to Boerzel et al. and U.S. Patent No. 5,739,355 to Gateau et al. When used in the aforementioned thermal ene reaction, due to enhanced reactivity, HR-PIB can increase the conversion rate in the reaction and reduce the amount of sediment formation. Suitable methods are described in U.S. Patent No. 7,897,696.

[0097] In one embodiment, the present disclosure further includes at least one dispersant derived from polyisobutylene succinic anhydride (“PIBSA”). The PIBSA can have an average of about 1.0 to about 2.0 succinic acid moieties per polymer.

[0098] Chromatographic techniques can be used to determine the active % of alkenyl or alkyl succinic anhydrides. This method is described in columns 5 and 6 of U.S. Patent No. 5,334,321.

[0099] Calculate the conversion percentage of the polyolefin from the activity % using the equations in columns 5 and 6 of U.S. Patent No. 5,334,321.

[0100] Unless otherwise indicated, all percentages are by weight and all molecular weights are number average molecular weights determined by gel permeation chromatography (GPC) using commercially available polystyrene standards (with number average molecular weights from 180 to about 18,000 as calibration references).

[0101] In one embodiment, the dispersant can be derived from polyalphaolefin (PAO) succinic anhydride. In one embodiment, the dispersant can be derived from an olefin maleic anhydride copolymer. As an example, the dispersant can be described as polyPIBSA. In one embodiment, the dispersant can be derived from an anhydride grafted to an ethylene-propylene copolymer.

[0102] Suitable classes of nitrogen-containing dispersants can be derived from olefin copolymers (OCPs), more specifically, ethylene-propylene dispersants that can be grafted with maleic anhydride. A more complete list of nitrogen-containing compounds that can react with the functionalized OCP is described in U.S. Patents 7,485,603; 7,786,057; 7,253,231; 6,107,257; and 5,075,383; and / or are commercially available.

[0103] The hydrocarbyl portion of the hydrocarbyl-dicarboxylic acid or anhydride of component A) can alternatively be derived from an ethylene-alpha olefin copolymer. These copolymers contain multiple ethylene units and multiple one or more C3-C 10 alpha-olefin units. The C3-C 10 alpha-olefin units can include propylene units.

[0104] As measured by GPC using polystyrene as a calibration reference, the ethylene-alpha olefin copolymer typically has a number average molecular weight of less than 5,000 g / mol; or the number average molecular weight of the copolymer can be less than 4,000 g / mol, or less than 3,500 g / mol, or less than 3,000 g / mol, or less than 2,500 g / mol, or less than 2,000 g / mol, or less than 1,500 g / mol, or less than 1,000 g / mol. In some embodiments, the number average molecular weight of the copolymer can be between 800 and 3,000 g / mol.

[0105] The ethylene content of the ethylene-α-olefin copolymer can be less than 80 mol%; less than 70 mol%, or less than 65 mol%, or less than 60 mol%, or less than 55 mol%, or less than 50 mol%, or less than 45 mol%, or less than 40 mol%. The ethylene content of the copolymer can be at least 10 mol% and less than 80 mol%, or at least 20 mol% and less than 70 mol%, or at least 30 mol% and less than 65 mol%, or at least 40 mol% and less than 60 mol%.

[0106] The C3-C of the ethylene-α-olefin copolymer 10 The α-olefin content can be at least 20 mol%, or at least 30 mol%, or at least 35 mol%, or at least 40 mol%, or at least 45 mol%, or at least 50 mol%, or at least 55 mol%, or at least 60 mol%.

[0107] In some embodiments, at least 70 mol% of the molecules of the ethylene-α-olefin copolymer can have an unsaturated group, and at least 70 mol% of the unsaturated groups can be located in the terminal vinylidene or a trisubstituted isomer of the terminal vinylidene, or at least 75 mol% of the copolymer terminates in the terminal vinylidene or a trisubstituted isomer of the terminal vinylidene, or at least 80 mol% of the copolymer terminates in the terminal vinylidene or a trisubstituted isomer of the terminal vinylidene, or at least 80 mol% of the copolymer terminates in the terminal vinylidene or a trisubstituted isomer of the terminal vinylidene, or at least 85 mol% of the copolymer terminates in the terminal vinylidene or a trisubstituted isomer of the terminal vinylidene, or at least 90 mol% of the copolymer terminates in the terminal vinylidene or a trisubstituted isomer of the terminal vinylidene, or at least 95 mol% of the copolymer terminates in the terminal vinylidene or a trisubstituted isomer of the terminal vinylidene. The terminal vinylidene and the trisubstituted isomer of the terminal vinylidene of the copolymer have one or more of the following structural formulas (A)-(C):

[0108]

[0109] wherein, R represents a C1-C8 alkyl group, and The indicated bond is attached to the remainder of the copolymer.

[0110] As determined by 13 13C NMR spectroscopy, the ethylene-α-olefin copolymer can have an average ethylene unit run length (n C2 ) of less than 2.8, and also satisfy the relationship shown by the following expression:

[0111]

[0112] where

[0113] EEE = (x C2 ) 3 ,

[0114] EEA = 2(x C2 ) 2 (1 - x C2 ),

[0115] AEA = x C2 (1 - x C2 ) 2 ,

[0116] x C2 is the mole fraction of ethylene incorporated into the polymer as measured by 1 H-NMR spectroscopy, E represents an ethylene unit, and A represents an α-olefin unit. The average ethylene unit run length of the copolymer can be less than 2.6, or less than 2.4, or less than 2.2, or less than 2. The average ethylene run length n c2 can also satisfy the relationship shown by the following expression:

[0117] where n C2,实际 < n C2,统计 .

[0118] The crossover temperature of the ethylene-α-olefin copolymer can be -20 °C or lower, or -25 °C or lower, or -30 °C or lower, or -35 °C or lower, or -40 °C or lower. The polydispersity index of the copolymer can be less than or equal to 4, or less than or equal to 3, or less than or equal to 2. Less than 20% of the unit triples in the copolymer can be ethylene-ethylene-ethylene triples, or less than 10% of the unit triples in the copolymer are ethylene-ethylene-ethylene triples, or less than 5% of the unit triples in the copolymer are ethylene-ethylene-ethylene triples. Other details of the ethylene-α-olefin copolymer and the dispersant made therefrom can be found in PCT / US18 / 37116 filed with the US Receiving Office, the disclosure of which is incorporated herein by reference in its entirety.

[0119] One class of suitable dispersants can be Mannich bases. Mannich bases are materials formed by the condensation of a higher molecular weight, alkyl-substituted phenol, a polyalkylene polyamine, and an aldehyde (such as formaldehyde). Mannich bases are described in more detail in U.S. Patent 3,634,515.

[0120] Suitable classes of dispersants can be high molecular weight esters or semi-ester amides. Suitable dispersants can also be post-treated by conventional methods by reaction with any of a variety of reagents. Among these are boron, urea, thiourea, dimercaptothiadiazole, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, maleic anhydrides, nitriles, epoxides, carbonates, cyclic carbonates, hindered phenol esters, and phosphorus compounds. US 7,645,726; US 7,214,649; and US 8,048,831 are hereby incorporated by reference in their entireties.

[0121] In addition to carbonate and borate aftertreatments, both compounds can be post-treated or further post-treated with a variety of post-treatment methods designed to improve or impart different properties. Such post-treatments include those outlined in columns 27 to 29 of U.S. Patent No. 5,241,003, which are incorporated herein by reference. Such treatments include treatment with: inorganic phosphorous acid or anhydrides (e.g., U.S. Patents 3,403,102 and 4,648,980); organic phosphorus compounds (e.g., U.S. Patent No. 3,502,677); phosphorus pentasulfide; boron compounds as already mentioned above (e.g., U.S. Patents 3,178,663 and 4,652,387); carboxylic acids, polycarboxylic acids, acid anhydrides, and / or acid halides (e.g., U.S. Patents 3,708,522 and 4,948,386); epoxides, polyepoxides, or thioepoxides (e.g., U.S. Patents 3,859,318 and 5,026,495); aldehydes or ketones (e.g., U.S. Patent No. 3,458,530); carbon disulfide (e.g., U.S. Patent No. 3,256,185); glycidol (e.g., U.S. Patent No. 4,617,137); ureas, thioureas, or guanidines (e.g., U.S. Patents 3,312,619; 3,865,813; and British Patent GB 1,065,595); organic sulfonic acids (e.g., U.S. Patent No. 3,189,544 and British Patent GB 2,140,811); vinyl cyanides (e.g., U.S. Patents 3,278,550 and 3,366,569); diketenes (e.g., U.S. Patent No. 3,546,243); diisocyanates (e.g., U.S. Patent No. 3,573,205); alkane sultones (e.g., U.S. Patent No. 3,749,695); 1,3-dicarbonyl compounds (e.g., U.S. Patent No. 4,579,675); sulfates of alkoxylated alcohols or phenols (e.g., U.S. Patent No. 3,954,639); cyclic lactones (e.g., U.S. Patents 4,617,138; 4,645,515; 4,668,246; 4,963,275; and 4,971,711); cyclic carbonates or thiocarbonates, linear monocarbonates or polycarbonates, or chloroformates (e.g., U.S. Patents 4,612,132; 4,647,390; 4,648,886; 4,670,170); nitrogen-containing carboxylic acids (e.g., U.S. Patent No. 4,971,598 and British Patent GB 2,140,811); hydroxy-protected chlorodicarbonyl-oxy compounds (e.g., U.S. Patent No. 4,614,522); lactams, thiolactams, thiolactones, or dithiolactones (e.g., U.S. Patents 4,614,603 and 4,666,460); cyclic carbonates or thiocarbonates, linear monocarbonates or polycarbonates, or chloroformates (e.g., U.S. Patents 4,612,132; 4,647,390; 4,646,860; and 4,670,170);Nitrogen-containing carboxylic acids (e.g., U.S. Patent No. 4,971,598 and British Patent GB 2,440,811); hydroxy-protected chlorodicarbonyl oxy compounds (e.g., U.S. Patent No. 4,614,522); lactams, thiolactams, thiolactones or dithiolactones (e.g., U.S. Patents Nos. 4,614,603 and 4,666,460); cyclic carbamates, cyclic thiocarbamates or cyclic dithiocarbamates (e.g., U.S. Patents Nos. 4,663,062 and 4,666,459); hydroxyaliphatic carboxylic acids (e.g., U.S. Patents 4,482,464; 4,521,318; 4,713,189); oxidizing agents (e.g., U.S. Patent No. 4,379,064); combinations of phosphorus pentasulfide and polyalkylene polyamines (e.g., U.S. Patent No. 3,185,647); combinations of carboxylic acids or aldehydes or ketones and sulfur or sulfur monochloride (e.g., U.S. Patents 3,390,086; 3,470,098); combinations of hydrazine and carbon disulfide (e.g., U.S. Patent No. 3,519,564); combinations of aldehydes and phenols (e.g., U.S. Patents 3,649,229; 5,030,249; 5,039,307); combinations of aldehydes and O-diesters of dithiophosphoric acid (e.g., U.S. Patent No. 3,865,740); combinations of hydroxyaliphatic carboxylic acids and boric acid (e.g., U.S. Patent No. 4,554,086); hydroxyaliphatic carboxylic acids, then combinations of formaldehyde and phenols (e.g., U.S. Patent No. 4,636,322); combinations of hydroxyaliphatic carboxylic acids with then aliphatic dicarboxylic acids (e.g., U.S. Patent No. 4,663,064); combinations of formaldehyde and phenols with then glycolic acid (e.g., U.S. Patent No. 4,699,724); combinations of hydroxyaliphatic carboxylic acids or oxalic acid, and then diisocyanates (e.g., U.S. Patent No. 4,713,191); combinations of inorganic acids or anhydrides of phosphorus or their partial or total sulfur analogs with boron-containing compounds (e.g., U.S. Patent No. 4,857,214); combinations of organic diacids, then unsaturated fatty acids with then nitrosoaromatic amines, optionally followed by boron compounds and then ethanolic acidifying reagents (e.g., U.S. Patent No. 4,973,412); combinations of aldehydes and triazoles (e.g., U.S. Patent No. 4,963,278); combinations of aldehydes and triazoles, then boron compounds (e.g., U.S. Patent No. 4,981,492); combinations of cyclic lactones and boron compounds (e.g., U.S. Patents Nos. 4,963,275 and 4,971,711). The patents mentioned above are incorporated herein by reference in their entirety.;

[0122] The TBN of a suitable dispersant can be about 10 to about 65 mg KOH / g of the dispersant on an oil-free basis, which is equivalent to about 5 TBN to about 30 TBN if measured on a dispersant sample containing about 50% diluent oil. TBN is measured by the method of ASTM D2896.

[0123] A dispersant, if present, may be used in an amount sufficient to provide up to about 20 wt% based on the final weight of the lubricating oil composition. Another amount of the dispersant that may be used may be from about 0.1 wt% to about 15 wt%, or from about 0.1 wt% to about 10 wt%, or from about 3 wt% to about 10 wt%, or from about 1 wt% to about 6 wt%, or from about 7 wt% to about 12 wt% based on the final weight of the lubricating oil composition. In some embodiments, the lubricating oil composition utilizes a mixed dispersant system. A single type of dispersant or a mixture of two or more types of dispersants may be used in any desired ratio.

[0124] Extreme pressure agent : The lubricating oil compositions herein may also optionally contain one or more extreme pressure agents. Extreme pressure (EP) agents soluble in oil include sulfur- and chlorosulfur-containing EP agents, chlorinated hydrocarbon EP agents, and phosphorus EP agents. Examples of such EP agents include chlorinated waxes; organic sulfides and polysulfides such as bis(dibenzyl) disulfide, bis(chlorobenzyl) disulfide, dibutyl tetrasulfide, methyl oleate sulfide, alkylphenol sulfide, dipentene sulfide, terpinene sulfide, sulfurized Diels-Alder adducts; phosphorothiohydrocarbons such as reaction products of phosphorus sulfide with turpentine or methyl oleate; phosphites such as dialkyl phosphites and trialkyl phosphites, e.g., dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, amylphenyl phosphite; dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite, and polypropylene-substituted phenyl phosphite; metal thiocarbamates such as zinc dioctyldithiocarbamate and barium heptylphenate diacid; amine salts of alkyl and dialkyl phosphoric acids, including for example amine salts of reaction products of dialkyl dithiophosphoric acid with propylene oxide; and mixtures thereof.

[0125] Friction modifier : The lubricating oil compositions herein may also optionally contain one or more friction modifiers. Suitable friction modifiers may include metal-containing and metal-free friction modifiers and may include, but are not limited to, imidazolines, amides, amines, succinimides, alkoxylated amines, alkoxylated ether amines, amine oxides, amidoamines, nitriles, betaines, quaternary amines, imines, amine salts, aminoguanidines, alkanolamides, phosphonates, metal-containing compounds, glycerol esters, sulfurized fatty compounds and olefins, sunflower oil, other naturally occurring vegetable or animal oils, dicarboxylic esters, esters or partial esters of polyols, and one or more aliphatic or aromatic carboxylic acids, etc.

[0126] Suitable friction modifiers may contain a hydrocarbon group selected from linear, branched or aromatic hydrocarbon groups or mixtures thereof, and may be saturated or unsaturated. The hydrocarbon group may consist of carbon and hydrogen or heteroatoms such as sulfur or oxygen. The hydrocarbon group may range from about 12 to about 25 carbon atoms. In some embodiments, the friction modifier may be a long-chain fatty acid ester. In another embodiment, the long-chain fatty acid ester may be a monoester or diester or (tri)glyceride. The friction modifier may be a long-chain fatty amide, long-chain fatty ester, long-chain fatty epoxide derivative or long-chain imidazoline.

[0127] Other suitable friction modifiers may include organic, ashless (metal-free), nitrogen-free organic friction modifiers. Such friction modifiers may include esters formed by reacting carboxylic acids and anhydrides with alkanols and generally contain a polar end group (e.g., carboxyl or hydroxyl) covalently bonded to a lipophilic hydrocarbon chain. Examples of organic ashless nitrogen-free friction modifiers are generally known as glycerol monooleate (GMO), which may contain mono-, di- and triesters of oleic acid. Other suitable friction modifiers are described in U.S. Patent No. 6,723,685, which is incorporated herein by reference in its entirety.

[0128] Amine friction modifiers may include amines or polyamines. Such compounds may have linear, saturated or unsaturated hydrocarbon groups, or mixtures thereof, and may contain from about 12 to about 25 carbon atoms. Other examples of suitable friction modifiers include alkoxylated amines and alkoxylated ether amines. Such compounds may have linear, saturated or unsaturated hydrocarbon groups, or mixtures thereof. They may contain from about 12 to about 25 carbon atoms. Examples include ethoxylated amines and ethoxylated ether amines.

[0129] Amines and amides may be used as such or in the form of an adduct or reaction product with a boron compound such as boron oxide, boron halide, boric acid ester, boric acid or monoalkyl, dialkyl or trialkyl borate. Other suitable friction modifiers are described in U.S. Patent No. 6,300,291.

[0130] The friction improver may optionally be present in a range of about 0 wt% to about 10 wt%, or about 0.01 wt% to about 8 wt%, or about 0.1 wt% to about 4 wt%.

[0131] Molybdenum-containing component: The lubricating oil composition herein may also optionally contain one or more molybdenum-containing compounds. The oil-soluble molybdenum compounds may have the functional properties of an anti-wear agent, an antioxidant, a friction modifier, or a mixture thereof. The oil-soluble molybdenum compounds may include molybdenum dithiocarbamate, molybdenum dialkyldithiophosphate, molybdenum dithiophosphite, amine salts of molybdenum compounds, molybdenum xanthate, molybdenum thioxanthate, molybdenum sulfide, molybdenum carboxylate, molybdenum alkanol, trinuclear organomolybdenum compounds, and / or mixtures thereof. Molybdenum sulfide includes molybdenum disulfide. Molybdenum disulfide may be in the form of a stable dispersion. In one embodiment, the oil-soluble molybdenum compound may be selected from molybdenum dithiocarbamate, molybdenum dialkyldithiophosphate, amine salts of molybdenum compounds, and mixtures thereof. In one embodiment, the oil-soluble molybdenum compound may be molybdenum dithiocarbamate.

[0132] Suitable examples of molybdenum compounds that can be used include commercial substances sold under the following trade names: Molyvan 822 from R.T. Vanderbilt Co., Ltd. TM , Molyvan TM A, Molyvan 2000 TM and Molyvan 855 TM and Sakura-Lube TM S-165, S-200, S-300, S-310G, S-525, S-600, S-700 and S-710, and mixtures thereof. Suitable molybdenum components are described in US5,650,381; US RE 37,363E1; US RE 38,929E1; and US RE 40,595E1, the entire contents of which are incorporated herein by reference.

[0133] Additionally, the molybdenum compound may be an acidic molybdenum compound. This includes molybdic acid, ammonium molybdate, sodium molybdate, potassium molybdate, and other molybdenum alkali metal salts, as well as other molybdenum salts, such as sodium hydrogen molybdate, MoOCl4, MoO2Br2, Mo2O3Cl6, molybdenum trioxide, or similar acidic molybdenum compounds. Alternatively, these compositions may provide molybdenum through a molybdenum / sulfur complex of a basic nitrogen compound, as described, for example, in U.S. Patents 4,263,152; 4,285,822; 4,283,295; 4,272,387; 4,265,773; 4,261,843; 4,259,195 and 4,259,194; and WO 94 / 06897, the entire contents of which are incorporated herein by reference.

[0134] Another suitable class of organomolybdenum compounds are trinuclear molybdenum compounds such as those having the formula Mo3SkLnQz and mixtures thereof, where S represents sulfur, L represents a ligand independently selected having an organic group having a number of carbon atoms sufficient to confer solubility or dispersibility of the compound in oil, n ranges from 1 to 4, k varies in the range from 4 to 7, Q is selected from the group of neutral electron donor compounds such as water, amines, alcohols, phosphines and ethers, and z ranges from 0 to 5 and includes non-stoichiometric values. There may be a total of at least 21 carbon atoms present in the organic groups of all ligands, such as at least 25, at least 30 or at least 35 carbon atoms. Other suitable molybdenum compounds are described in U.S. Patent 6,723,685, the entire contents of which are incorporated herein by reference.

[0135] The oil-soluble molybdenum compound may be present in an amount sufficient to provide from about 0.5 ppm to about 2000 ppm, about 1 ppm to about 700 ppm, about 1 ppm to about 550 ppm, about 5 ppm to about 300 ppm, or about 20 ppm to about 250 ppm of molybdenum.

[0136] Compound containing transition metal : In another embodiment, the oil-soluble compound may be a transition metal-containing compound or a metalloid. Transition metals may include, but are not limited to: titanium, vanadium, copper, zinc, zirconium, molybdenum, tantalum, tungsten, etc. Suitable metalloids include, but are not limited to: boron, silicon, antimony, tellurium, etc.

[0137] In one embodiment, the oil-soluble transition metal-containing compound can function as an antiwear agent, friction modifier, antioxidant, deposit control additive, or more than one of these functions. In one embodiment, the oil-soluble transition metal-containing compound can be an oil-soluble titanium compound, such as titanium(IV) alkoxide. There are various Ti(IV) compounds among the titanium-containing compounds that can be used in the disclosed technology or can be used to prepare the oil-soluble materials of the disclosed technology, such as titanium(IV) oxide; titanium(IV) sulfide; titanium(IV) nitrate; titanium(IV) alkoxides, such as titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, titanium 2-ethylhexoxide; and other titanium compounds or complexes, including but not limited to titanium phenoxide; titanium carboxylates, such as titanium(IV) 2-ethyl-1,3-hexanedioate or titanium citrate or titanium oleate; and titanium(IV) (triethanolamine) isopropoxide. Other forms of titanium covered within the disclosed technology include titanium phosphates, such as titanium dithiophosphate (e.g., dialkyldithiophosphate titanium), and titanium sulfonates (e.g., alkylbenzenesulfonate titanium), or generally, the reaction products of titanium compounds with various acidic materials to form salts (such as oil-soluble salts). Titanium compounds can thus be derived in particular from organic acids, alcohols, and diols. Ti compounds can also exist in dimeric or oligomeric forms, containing a Ti--O--Ti structure. Such titanium materials are commercially available or can be readily prepared by suitable synthetic techniques obvious to those skilled in the art. They exist in solid or liquid form at room temperature, depending on the specific compound. They can also be provided in the form of a solution in a suitable inert solvent.

[0138] In one embodiment, titanium can be supplied as a Ti-modified dispersant, such as a succinimide dispersant. Such materials can be prepared by forming a titanium mixed anhydride between a titanium alkoxide and a hydrocarbyl-substituted succinic anhydride (such as an alkenyl (or alkyl) succinic anhydride). The resulting titanate-succinate intermediate can be used directly, or it can be reacted with any of a number of materials, such as (a) a polyamine-based succinimide / amide dispersant having a free, condensable --NH functional group; (b) components of a polyamine-based succinimide / amide dispersant, namely an alkenyl-(or alkyl-)succinic anhydride and a polyamine, (c) a hydroxy-containing polyester dispersant prepared by reacting a substituted succinic anhydride with a polyol, an amino alcohol, a polyamine, or a mixture thereof. Alternatively, the titanate-succinate intermediate can be reacted with other reagents, such as an alcohol, an amino alcohol, an ether alcohol, a polyether alcohol, or a polyol or a fatty acid, and the product can be used directly to impart Ti to a lubricant, or alternatively, as described herein, further reacted with a succinic acid dispersant. As an example, 1 part (by mole) of titanium tetraisopropoxide can be reacted with about 2 parts (by mole) of polyisobutylene-substituted succinic anhydride at 140 °C - 150 °C for 5 to 6 hours to provide a Ti-modified dispersant or intermediate. The resulting material (30 g) can be further reacted with a succinimide dispersant and a mixture of polyethylene polyamine from polyisobutylene-substituted succinic anhydride (127 g + diluent oil) at 150 °C for 1.5 hours to produce a Ti-modified succinimide dispersant.

[0139] Another titanium-containing compound can be the reaction product of a titanium alkoxide and a C6 to C 25 carboxylic acid. The reaction product can be represented by the formula:

[0140]

[0141] where n is an integer selected from 2, 3, and 4, and R is a hydrocarbyl group containing from about 5 to about 24 carbon atoms, or is represented by the formula:

[0142]

[0143] where m + n = 4 and n ranges from 1 to 3, R4 is an alkyl moiety having from 1 to 8 carbon atoms, R1 is selected from hydrocarbyl groups containing from about 6 to 25 carbon atoms, and R2 and R3 are the same or different and are selected from hydrocarbyl groups containing from about 1 to 6 carbon atoms, or the titanium compound can be represented by the formula:

[0144]

[0145] where x ranges from 0 to 3, R1 is selected from hydrocarbyl groups containing from about 6 to 25 carbon atoms, R2 and R3 are the same or different and are selected from hydrocarbyl groups containing from about 1 to 6 carbon atoms, and R4 is selected from the group consisting of H, or a C6 to C 25 carboxylic acid moiety.

[0146] Suitable carboxylic acids can include, but are not limited to, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, oleic acid, erucic acid, linoleic acid, linolenic acid, cyclohexanecarboxylic acid, phenylacetic acid, benzoic acid, neodecanoic acid, etc.

[0147] In one embodiment, the oil-soluble titanium compound can be present in the lubricating oil composition in an amount of 0 to 3000 ppm titanium by weight, or 25 to about 1500 ppm titanium by weight, or about 35 ppm to 500 ppm titanium by weight, or about 50 ppm to about 300 ppm.

[0148] Viscosity index improver : The lubricating oil compositions herein may also optionally contain one or more viscosity index improvers. Suitable viscosity index improvers can include polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutylene, hydrogenated styrene-isoprene polymers, styrene / maleate copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkylstyrenes, hydrogenated vinyl aromatic conjugated diene copolymers, or mixtures thereof. The viscosity index improver may include star polymers, and suitable examples are described in U.S. Publication No. 20120101017A1.

[0149] The lubricating oil compositions herein may also optionally contain one or more dispersant viscosity index improvers in addition to or in place of the viscosity index improvers. Suitable viscosity index improvers can include functionalized polyolefins, such as 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 an amine, or esterified maleic anhydride-styrene copolymers reacted with an amine.

[0150] The total amount of the viscosity index improver and / or the dispersant viscosity index improver can 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% of the lubricating oil composition.

[0151] Other optional additives : Other additives can be selected to perform one or more functions required of the lubricating fluid. Additionally, one or more of the additives mentioned can be multifunctional and provide functions other than or different from the functions specified herein.

[0152] The lubricating oil composition according to the present disclosure may optionally contain other performance additives. The other performance additives may be additives other than the specified additives of the present disclosure and / or may include one or more of the following: metal deactivators, viscosity index improvers, detergents, ashless TBN boosters, friction modifiers, antiwear agents, corrosion inhibitors, rust inhibitors, dispersants, dispersant viscosity index improvers, extreme pressure agents, antioxidants, foam inhibitors, demulsifiers, emulsifiers, pour point depressants, seal swell agents, and mixtures thereof. Generally, a full-formulation lubricating oil will contain one or more of these performance additives.

[0153] Suitable metal deactivators may include derivatives of benzotriazole (usually tolyltriazole), dimercaptothiadiazole 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 glycols, polyethylene oxides, polypropylene oxides, and (ethylene oxide - propylene oxide) polymers; pour point depressants, including esters of maleic anhydride - styrene, polymethacrylates, polyacrylates, or polyacrylamides.

[0154] Suitable foam inhibitors include silicon-based compounds such as siloxanes.

[0155] 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.%, 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.

[0156] Suitable rust inhibitors may be a single compound or a mixture of compounds having the property of inhibiting corrosion of iron metal surfaces. Non-limiting examples of rust inhibitors useful herein include: oil-soluble high molecular weight organic acids such as 2-ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, and cerotic acid; and oil-soluble polycarboxylic acids including dimer acids and trimer acids such as those produced from tall oil fatty acids, oleic acid, and linoleic acid. Other suitable corrosion inhibitors include long-chain α,ω-dicarboxylic acids having a molecular weight in the range of about 600 to about 3000, and alkenyl succinic acids in which the alkenyl group contains about 10 or more carbon atoms, such as tetrapropenyl succinic acid, tetradecenyl succinic acid, and hexadecenyl succinic acid. Another type of acidic corrosion inhibitor useful 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 polyethylene glycol). The corresponding semi-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.

[0157] An anti-rust agent (if present) may be used in an amount sufficient to provide from about 0 wt% to about 5 wt%, from about 0.01 wt% to about 3 wt%, or from about 0.1 wt% to about 2 wt% based on the final weight of the lubricating oil composition.

[0158] Generally, suitable crankcase lubricants may include additive components within the ranges listed in the following table.

[0159] Table 2: Suitable lubricating compositions

[0160]

[0161] Based on the weight of the final lubricating oil composition, the percentages of each of the above components represent the weight percentages of each component. The remainder of the lubricating oil composition consists of one or more base oils. The additives used to formulate the compositions described herein may be blended into the base oil individually or in various sub-combinations. However, it may be appropriate to use an additive concentrate (i.e., an additive plus a diluent, such as a hydrocarbon solvent) to blend all components simultaneously.

[0162] Example

[0163] The following examples are illustrative of 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.

[0164] Example 1

[0165] Engine oils formulated for 0W-20 oil grades and including a modified styrene-maleic anhydride copolymer (PSMA) or a poly(meth)acrylate copolymer (PMA) are evaluated separately according to the MRV test (ASTM D4684, at -40 °C), as shown in Table 3 below. Even with a treatment rate of 0.5 wt% of the copolymer, the formulation fails the MRV test using only the PSMA or PMA polymer. The base formulation remains unchanged, and the only variation is the polymer as described in Table 3 below. The base formulation is prepared to meet ILSAC GF-6 and contains appropriate amounts of succinimide dispersant, borated succinimide dispersant, overbased calcium sulfonate, overbased magnesium sulfonate, zinc dialkyldithiophosphate, alkylated diphenylamine antioxidant, antifoaming agent, organic friction modifier, and DI packaging of base oil. Base oil 1 and base oil 2 are Group III base oils. The viscosity modifier is an olefin copolymer. The polymers considered for this example are further described in Table 4 below. The MRV viscosity and yield stress are measured according to ASTM D4684, and the kinematic viscosity is measured according to ASTM D445. Acceptable MRV includes a viscosity of less than 60,000 cP and a yield stress of less than 35. According to the resplit convention of the test method, a resplit yield stress of <70 means the yield stress is between 35 and 75.

[0166] Table 3: Comparative examples of single polymer formulations 。

[0167]

[0168] Table 4: Polymers

[0169] PSMA PMA-1 PMA-2 PMA-3 Polymer Esterified styrene-maleic anhydride* PMA** PMA** PMA** Mn 42000 39000 34000 39000 PDI 2.9 1.8 1.9 1.8 Active polymer % 32 64.4 65.5 68.9

[0170] *The esterified styrene-maleic anhydride copolymer is esterified with a long-chain alcohol having a chain length of 10 to 20 carbons

[0171] **The PMA polymer is a poly(meth)acrylate polymer that is a blend including one or more of C1-C4 (meth)acrylate; C12-C16 (meth)acrylate; and / or C16-

[0172] C20 (meth)acrylate.

[0173] Example 2

[0174] This example combines the PSMA polymer and the PMA copolymer of Example 1. It was surprisingly found that such copolymer mixtures can contribute to passing the MRV test when different chemicals are combined. Table 5 below shows that Examples I1, I2, and I3 of the present invention having a combination of PSMA and PMA polymers contribute to passing the MRV test.

[0175] Table 5: Examples of the present invention of polymer mixture formulations 。

[0176]

[0177] Example 3

[0178] This example only combines different PMA copolymers of Example 1. Examples C5 and C6 in Table 6 show that the combination of PMA-1, PMA-2, and PMA-3 cannot pass the MRV test.

[0179] Table 6: Comparative examples of polymer mixture formulations 。

[0180]

[0181] Example 4

[0182] This example evaluates different ratios of PSMA and PMA copolymers of Example 1. Comparative Examples C7 and C8 in Table 7 show the ratios that cannot pass the MRV test, while the ratios in the samples I4-I7 of the present invention can achieve passing MRV performance. The fluid in this example includes the lubricant composition as described in Example 1, except as noted in Table 7 below.

[0183] Table 7: Comparative examples and examples of the present invention of polymer mixture formulations 。

[0184] C7 C8 I4 I5 I6 I7 Polymer blend treatment rate (%) 0.5 0.5 0.5 0.5 0.5 0.55 PSMA % in the blend 0％ 20％ 40％ 50％ 60％ 55％ PSMA (%) 0.1 0.2 0.25 0.3 0.3 PMA-3 (%) 0.5 0.4 0.3 0.25 0.2 0.25 KV100℃ (cSt) 8.3 8.4 8.2 8.4 8.1 8.2 MRV TP-1 viscosity (cP) 30800 36900 28465 27725 25200 24900 MRV TP-1 yield stress <70 <70 <35 <35 <35 <35 MRV Pass / Fail Fail Fail Pass Pass Pass Pass

[0185] Example 5

[0186] This example evaluates different treatment rates of the total PSMA and PMA polymer blends using the polymers of Example 1. Comparative Examples C9 and C11 in Table 8 show that the lower total treatment rates of the two polymers cannot pass the MRV test, while the samples I8-I12 of the present invention can achieve passing MRV performance. The fluid in this example includes the lubricant composition as described in Example 1, except as noted in Table 8 below.

[0187] Table 8: Comparative examples and examples of the present invention of polymer mixture formulations 。

[0188]

[0189] Note that, unless explicitly and affirmatively limited to one referent, the singular forms "a / an" and "the" as used in this specification and the appended claims include plural referents. Thus, for example, reference to "an antioxidant" includes two or more different antioxidants. The term "comprising" and its grammatical variants as used herein are intended to be non-limiting, such that recitation of items in a list does not preclude other similar items that may be substituted or added to the listed items.

[0190] For this specification and the appended claims, unless otherwise indicated, all numbers expressing quantities, percentages, or proportions, and other numerical values used in the specification and claims shall be understood to be modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by this 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.

[0191] It should be understood that each component, compound, substituent, or parameter disclosed herein is to be interpreted as being disclosed for use alone or in combination with one or more of each of the other components, compounds, substituents, or parameters disclosed herein.

[0192] It should be further understood that each range disclosed herein is to be interpreted as an open disclosure of every specific value within the range having the same numerical value of significant digits. Thus, for example, a range of 1 to 4 is to be interpreted as an express disclosure of the values 1, 2, 3, and 4 and any range of such values.

[0193] It should be further understood that each lower limit of each range disclosed herein is to be interpreted as being disclosed in combination with each upper limit of each range and each specific value within each range for the same component, compound, substituent, or parameter disclosed herein. Thus, this disclosure is to be interpreted as an open disclosure of 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 to say, it should be further understood that any range between the endpoint values within the broad ranges is also discussed herein. Thus, a range of 1 to 4 also means ranges of 1 to 3, 1 to 2, 2 to 4, 2 to 3, etc.

[0194] In addition, the specific amounts / values of components, compounds, substituents, or parameters disclosed in this specification or the examples should be interpreted as the disclosure of the lower or upper limit of a certain range, and thus can be combined with any other lower or upper limit or specific amount / value of the range of the same components, compounds, substituents, or parameters disclosed elsewhere in this disclosure to form the range of that component, compound, substituent, or parameter.

[0195] Although particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently foreseen or that may not currently be foreseen by the applicant or other skilled artisans in the art may be contemplated. Accordingly, 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 low-temperature stable lubricating composition that exhibits pumpability measured at -40 °C in an MRV test according to ASTM D4684, the low-temperature stable lubricating composition comprising: a base oil having a lubricating viscosity; 0.5 to 1.0 wt% of a polymer additive that effectively maintains a pumpable fluid, the polymer additive comprising a blend of an esterified styrene-maleic anhydride copolymer and a poly(meth)acrylate copolymer, wherein the weight ratio of the esterified styrene-maleic anhydride copolymer to the poly(meth)acrylate copolymer is from 1:2 to 1:0.7, wherein the esterified styrene-maleic anhydride copolymer is esterified with a long-chain alcohol having an alkyl chain length of 10 to 22 carbons, and wherein the poly(meth)acrylate copolymer comprises one or more of C1-C4 (meth)acrylate; C12-C16 (meth)acrylate; and / or C16-C20 (meth)acrylate.

2. The low-temperature stable lubricating composition according to claim 1, wherein the lubricating composition further comprises one or more of a succinimide dispersant, a borated succinimide dispersant, a highly basic calcium sulfonate, a highly basic magnesium sulfonate, a zinc dialkyldithiophosphate, an alkylated diphenylamine antioxidant, an antifoaming agent, or a combination thereof.

3. The low-temperature stable lubricating composition according to claim 1 or 2, wherein the esterified styrene-maleic anhydride copolymer has a number average molecular weight of 10,000 to 100,000.

4. The low-temperature stable lubricating composition according to claim 1, wherein the poly(meth)acrylate copolymer has a number average molecular weight of 20,000 or higher.

5. A method for maintaining the pumpable viscosity of a lubricating composition, the method comprising adding to the lubricating composition an additive according to claims 1 to 4 that effectively maintains a pumpable fluid, as demonstrated by passing MRV performance at temperatures as low as -40 °C.

6. Use of the polymer additive according to claims 1 to 4 for achieving passing MRV pumpability at -40 °C according to ASTM D4684.

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