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OF THE INVENTION
The present invention relates to a low sulfur, low ash, low phosphorous lubricant composition and method for lubricating an internal combustion engine, providing improved fuel economy and retention of fuel economy and wear and friction reduction.
Fuel economy is of great importance, and lubricants which can foster improved fuel economy by, for instance, reducing friction within an engine, are of significant value. The present invention provides a low sulfur, low ash, low phosphorous lubricant composition, including an additive package, which leads to improved fuel economy in an internal combustion engine. This improvement is effected by providing an additive package in which the friction modifier component is exclusively or predominantly a tartrimide or a tartramide or combinations thereof.
U.S. Pat. No. 4,237,022, Barrer, Dec. 2, 1980, discloses tartrimides useful as additives in lubricants and fuels for effective reduction in squeal and friction as well as improvement in fuel economy.
U.S. Pat. No. 4,952,328, Davis et al., Aug. 28, 1990, discloses lubricating oil compositions for internal combustion engines, comprising (A) oil of lubricating viscosity, (B) a carboxylic derivative produced by reacting a succinic acylating agent with certain amines, and (C) a basic alkali metal salt of sulfonic or carboxylic acid. An illustrative lubricant composition (Lubricant III) includes base oil including viscosity index modifier; a basic magnesium alkylated benzene sulfonate; an overbased sodium alkylbenzene sulfonate; a basic calcium alkylated benzene sulfonate; succinimide dispersant; and zinc salts of a phosphorodithioic acids.
U.S. Pat. No. 4,326,972, Chamberlin, Apr. 27, 1982, discloses lubricant compositions for improving fuel economy of internal combustion engines. The composition includes a specific sulfurized composition (based on an ester of a carboxylic acid) and a basic alkali metal sulfonate. Additional ingredients may include at least one oil-dispersible detergent or dispersant, a viscosity improving agent, and a specific salt of a phosphorus acid.
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OF THE INVENTION
The present invention provides a low-sulfur, low-phosphorus, low-ash lubricant composition suitable for lubricating an internal combustion engine, comprising the following components:
(a) an oil of lubricating viscosity, and
(b) a condensation product of a material represented by formula I and an alcohol or amine having about 8 to about 30 carbon atoms and combinations thereof;
wherein each R is independently H or a hydrocarbyl group, or wherein the R groups together form a ring; and wherein if R is H, the condensation product is optionally further functionalized by acylation or reaction with a boron compound;
wherein said lubricant composition has a sulfated ash value of up to about 1.0, a phosphorus content of up to about 0.08 percent by weight and a sulfur content of up to about 0.4 percent by weight.
It further provides a method of lubricating an internal combustion engine, comprising supplying the lubricant composition to the engine.
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OF THE INVENTION
Various preferred features and embodiments will be described below by way of non-limiting illustration.
The present invention provides a composition as described above. Often the composition has total sulfur content in one aspect below 0.4 percent by weight, in another aspect below 0.3 percent by weight, in yet another aspect 0.2 percent by weight or less and in yet another aspect 0.1 percent by weight or less. Often the major source of sulfur in the composition of the invention is derived from conventional diluent oil. A typical range for the total sulfur content is 0.1 to 0.01 percent by weight.
Often the composition has a total phosphorus content of less than or equal to 800 ppm, in another aspect equal to or less than 500 ppm, in yet another aspect equal to or less than 300 ppm, in yet another aspect equal to or less than 200 ppm and in yet another aspect equal to or less than 100 ppm of the composition. A typical range for the total phosphorus content is 500 to 100 ppm.
Often the composition has a total sulfated ash content as determined by ASTM D-874 of below 1.0 percent by weight, in one aspect equal to or less than 0.7 percent by weight, in yet another aspect equal to or less than 0.4 percent by weight, in yet another aspect equal to or less than 0.3 percent by weight and in yet another aspect equal to or less than 0.05 percent by weight of the composition. A typical range for the total sulfate ash content is 0.7 to 0.05 percent by weight.
Oil of Lubricating Viscosity
The low-sulfur, low-phosphorus, low-ash lubricating oil composition is comprised of one or more base oils which are generally present in a major amount (i.e. an amount greater than about 50 percent by weight). Generally, the base oil is present in an amount greater than about 60 percent, or greater than about 70 percent, or greater than about 80 percent by weight of the lubricating oil composition. The base oil sulfur content is typically less than 0.2 percent by weight.
The low-sulfur, low-phosphorus, low-ash lubricating oil composition may have a viscosity of up to about 16.3 mm2/s at 100° C., and in one embodiment 5 to 16.3 mm2/s (cSt) at 100° C., and in one embodiment 6 to 13 mm2/s (cSt) at 100° C. In one embodiment, the lubricating oil composition has an SAE Viscosity Grade of 0W, 0W-20, 0W-30, 0W-40, 0W-50, 0W-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50, 5W-60, 10W, 10W-20, 10W-30, 10W-40 or 10W-50.
The low-sulfur, low-phosphorus, low-ash lubricating oil composition may have a high-temperature/high-shear viscosity at 150° C. as measured by the procedure in ASTM D4683 of up to 4 mm2/s (cSt), and in one embodiment up to 3.7 mm2/s (cSt), and in one embodiment 2 to 4 mm2/s (cSt), and in one embodiment 2.2 to 3.7 mm2/s (cSt), and in one embodiment 2.7 to 3.5 mm2/s (cSt).
The base oil used in the low-sulfur low-phosphorus, low-ash lubricant composition may be a natural oil, synthetic oil or mixture thereof, provided the sulfur content of such oil does not exceed the above-indicated sulfur concentration limit required for the inventive low-sulfur, low-phosphorus, low-ash lubricating oil composition. The natural oils that are useful include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as mineral lubricating oils such as liquid petroleum oils and solvent treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils derived from coal or shale are also useful. Synthetic lubricating oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene isobutylene copolymers, etc.); poly(1-hexenes), poly-(1-octenes), poly(1-decenes), etc. and mixtures thereof; alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls, etc.); alkylated diphenyl ethers and the derivatives, analogs and homologs thereof and the like.
Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils that can be used. These are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having an average molecular weight of about 1000, diphenyl ether of polyethylene glycol having a molecular weight of about 500-1000, diethyl ether of polypropylene glycol having a molecular weight of about 1000-1500, etc.) or mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C3-8 fatty acid esters, or the carboxylic acid diester of tetraethylene glycol.
Another suitable class of synthetic lubricating oils that can be used comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc.) Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid and the like.
Esters useful as synthetic oils also include those made from C5 to C12 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol, etc.
The oil can be a poly-alpha-olefin (PAO). Typically, the PAOs are derived from monomers having from 4 to 30, or from 4 to 20, or from 6 to 16 carbon atoms. Examples of useful PAOs include those derived from octene, decene, mixtures thereof, and the like. These PAOs may have a viscosity from 2 to 15, or from 3 to 12, or from 4 to 8 mm2/s (cSt), at 100° C. Examples of useful PAOs include 4 mm2/s (cSt) at 100° C. poly-alpha-olefins, 6 mm2/s (cSt) at 100° C. poly-alpha-olefins, and mixtures thereof. Mixtures of mineral oil with one or more of the foregoing PAOs may be used.
Unrefined, refined and rerefined oils, either natural or synthetic (as well as mixtures of two or more of any of these) of the type disclosed hereinabove can be used in the lubricants of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from primary distillation or ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those skilled in the art such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products.
Additionally, oils prepared by a Fischer-Tropsch gas to liquid synthetic procedure are known and can be used.
The tartrimides, tartramides or combinations thereof of the present invention can be prepared by the reaction of tartaric acid and one or more amines, for example, having the formula RR′NH wherein R and R′ each independently represent H, a hydrocarbon-based radical of 1 to 150 carbon atoms provided that the sum of carbon atoms in R and R′ is at least 8, or —R″OR″′ in which R″ is a divalent alkylene radical of 2 to 6 carbon atoms and R″′ is a hydrocarbyl radical of 5 to 150 carbon atoms.
Amines suitable for the present tartrimide, tartramides or combinations thereof include those represented by the formula or RR′NH wherein R and R′ represent H or a long chain hydrocarbyl radical of 1 to 150 carbon atoms provided that the sum of the carbon atoms in R and R′ is at least 8. In one embodiment R or R′ contain 8 to 26 carbons and in another embodiment from 12 to 18 carbon atoms.