JP2012504175A - Lubricating oil composition - Google Patents

Abstract

A lubricating oil composition is provided.
A lubricating oil composition comprises (a) an oil having a major amount of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent, (d) an antioxidant, and (E) Contains an antiwear agent, does not contain a zinc dialkyldithiophosphate, and does not substantially contain phosphorus.
[Selection figure] None

Description

  The present invention relates generally to lubricating oil compositions for reducing wear within an engine.

  Automotive spark ignition and diesel engines have a valve system including, for example, valves, cams, and rocker arms. These are particularly related to lubricity. It is crucial that the lubricant, ie engine oil, protect these parts from wear. For engine oils, it is also important to suppress the formation of deposits in the engine. Such deposits are caused by non-combustible and incomplete combustion of hydrocarbon fuels (eg, gasoline and diesel fuel oils) due to deterioration of the engine oil used.

  Typical engine oils use mineral oil or synthetic oil as the base oil. However, a simple base oil alone cannot provide a function for realizing wear prevention, accumulation control, and the like required for protecting an internal combustion engine. Therefore, base oils share auxiliary functions such as ashless dispersants, metal detergents (metal-containing detergents), antiwear agents, antioxidants (antioxidants), viscosity index improvers, etc. Various additives are formulated, and a pre-defined oil (lubricating oil composition) is supplied.

  Many such engine oil additives are known and used in practice. For example, zinc dialkyldithiophosphates are commonly included in commercial internal combustion engine oils, particularly engine oils used in automobiles, because of their desirable properties as antiwear agents and performance as antioxidants.

  On the other hand, a problem with the use of zinc dialkyldithiophosphates is that their phosphorus and sulfur derivatives harm the catalytic components of the catalytic converter. This means that an effective catalytic converter is needed, and the catalytic converter reduces pollution and harmful gases in the exhaust emitted by internal combustion engines such as hydrocarbons, carbon monoxide, and nitrogen oxides. It has a lot to do with what is needed to comply with government regulations enacted to reduce Such catalytic converters generally use a combination of a catalytic metal (eg, platinum) and a metal oxide. Catalytic converters are installed in exhaust airflow (eg, automobile exhaust pipes) to convert toxic gases to non-toxic gases. As already mentioned, these catalyst components are damaged by the phosphorus and sulfur components of zinc dialkyldithiophosphates or by phosphorus and sulfur decomposition products. Thus, the use of engine oils containing phosphorus and sulfur additives significantly reduces the life and effectiveness of the catalytic converter.

  There is also pressure from the government and the automotive industry on reducing the phosphorus and sulfur content. For example, current GF-4 automotive oil specifications require that the pre-defined oil have a content of less than 0.08% by weight of phosphorus and less than 0.7% by weight of sulfur. . The specification for CJ-4 automotive oil is less than 0.12% by weight phosphorus, less than 0.4% by weight sulfur, and less than 1.0% by weight sulfated ash for the latest generation of durable diesel engine oils. It is demanding that the amount. It is widely believed that reducing to such limits can have a serious impact on engine performance, engine durability, and engine oil oxidation. This is because most of the phosphorus content in engine oil has historically originated from zinc dialkyldithiophosphate. Accordingly, it is desirable to reduce the amount of zinc dialkyldithiophosphate from the lubricating oil, thereby inhibiting catalyst deactivation and further improving the life and effectiveness of the catalytic converter. At the same time, it is also desirable to match the phosphorus and sulfur content in engine oils to the proposed future industry standards. However, simply reducing the amount of zinc dialkyldithiophosphate causes problems. This is because it is inevitable that the anti-wear and anti-oxidation performance of the lubricating oil will be reduced. Therefore, there is a need to find a way to reduce or eliminate phosphorus and sulfur content while still maintaining anti-wear properties in engine oils with high phosphorus and sulfur content.

  As described above, since the demand for further reducing the phosphorus content of the lubricating oil and limiting the sulfur content is very high, the current practical method cannot satisfy such a reduction demand. . Not only that, it still fails to meet the stringent wear resistance requirements of today's engine oils. Accordingly, it is desirable to develop a lubricating oil composition that provides relatively low levels of phosphorus and sulfur, but provides the required anti-wear performance. However, their performance is still provided by lubricating oils that still contain zinc dialkyldithiophosphates. Therefore, an improved lubricating oil that does not contain zinc and is relatively low or absent in phosphorus and / or sulfur content, but exhibits improved wear resistance when used in an internal combustion engine. It would also be desirable to develop a composition.

  The lubricating oil composition provided according to the first aspect of the present invention comprises (a) an oil having a major amount of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent. (D) an antioxidant, and (e) an antiwear agent, and the lubricating oil composition is free of a zinc dialkyldithiophosphate compound and is substantially free of phosphorus (i.e., has a substantial phosphorus content). not exist).

  The lubricating oil composition provided according to the second aspect of the present invention comprises (a) an oil having a major amount of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent. (D) an antioxidant, and (e) an antiwear agent, and the lubricating oil composition is free of zinc dialkyldithiophosphate compound and substantially free of phosphorus, and the lubricating oil composition is a lubricating oil composition. It has a greater wear reduction function than a corresponding composition in which a zinc dialkyldithiophosphate compound is present in the product.

  A method for improving the wear reducing function of a lubricating oil composition provided according to the third aspect of the present invention comprises: (a) an oil having a major amount of lubricating viscosity, (b) an ashless dispersant, (c) Producing a lubricating oil composition comprising at least one metal-containing detergent, (d) an antioxidant, and (e) an antiwear agent, wherein the lubricating oil composition does not comprise a zinc dialkyldithiophosphate compound; Contains substantially no phosphorus.

  In a fourth aspect of the invention, (a) an oil having a major amount of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent, (d) an antioxidant, and (E) A lubricating oil composition comprising an anti-wear agent, further comprising operating the internal combustion engine using a lubricating oil composition that does not contain a zinc dialkyldithiophosphate compound and substantially does not contain phosphorus. A method of reducing internal wear is provided.

  In a fifth aspect of the invention, (a) an oil having a major amount of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent, (d) an antioxidant, and (E) An internal combustion engine having a lubricating action using a lubricating oil composition containing an antiwear agent and further containing no zinc dialkyldithiophosphate compound and substantially free of phosphorus. Provided.

  The lubricating oil composition of the present invention does not contain a zinc dialkyldithiophosphate compound, but advantageously has improved wear reduction compared to a corresponding lubricating oil composition in which the zinc dialkyldithiophosphate compound is present in the lubricating oil composition. It has a function. This is an unexpected result considering that zinc dialkyldithiophosphate is a known anti-wear agent commonly used in lubricating oil compositions. In addition, an improved wear reduction function is achieved with the lubricating oil composition of the present invention that further has a relatively low or absent phosphorus content and a relatively low level of sulfur.

3 is a bar graph comparing the antiwear performance of the lubricating oil composition of Example 1 against the lubricating oil compositions of Comparative Examples A and B.

  The present invention comprises at least (a) an oil having a major amount of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent, (d) an antioxidant, and (e) a dialkyl. The present invention relates to a lubricating oil composition comprising an antiwear agent other than a zinc dithiophosphate compound, and the lubricating oil composition is free of a zinc dialkyldithiophosphate compound and is substantially free of phosphorus content (ie, substantially contains phosphorus). do not do). For example, the phosphorus content is 0.08% by mass or less, more preferably 0.05% by mass or less, and most preferably 0% by mass with respect to the total mass of the lubricating oil. In another aspect, the lubricating oil composition of the present invention has a relatively low level of sulfur, for example 0.7% by weight or less, preferably 0.2% by weight or less. The amount of phosphorus and sulfur in the lubricating oil composition of the present invention is measured according to ASTM D4951.

  The oil having a lubricating viscosity used in the lubricating oil composition of the present invention is also referred to as a base oil and is generally present in large amounts relative to the total weight of the composition, specifically more than 50% by weight, Preferably more than about 70% by weight, more preferably about 80 to about 99.5% by weight, and most preferably about 85 to about 98% by weight. As used herein, the expression “base oil” should be understood to mean a base stock or a combination of base stocks. This base stock is produced by a single manufacturer based on the same specification (regardless of where the raw material is supplied or where it is manufactured); conforms to the same manufacturer's specification, and also has a unique recipe, product identification number or It is a lubricious component identified by both of them. The base oil used here may be a base oil discovered in the future in addition to those already known. This base oil is used in formulating lubricating oil compositions in some or all applications, such as engine oils, marine cylinder oils, functional liquids (eg, hydraulic oils, gear oils, transmission fluids), etc. Has a lubricating viscosity. In addition, the base oil used here is a viscosity index such as alkyl methacrylate polymers, olefin copolymers (eg, ethylene-propylene copolymers, styrene-butadiene copolymers) and the like, and mixtures thereof. An enhancer can optionally be included.

  As will be readily appreciated by those skilled in the art, the viscosity of the base oil depends on the application. That is, the viscosity of the base oil used here is typically in the range of about 2 to about 2000 centistokes (cSt) at 100 ° C. The individual base oils used as engine oils generally have a kinematic viscosity at 100 ° C. in the range of about 2 cSt to about 30 cSt, preferably about 3 cSt to about 16 cSt, and most preferably about 4 cSt to about 12 cSt. Also, the base oil is selected and formulated according to the required end use and the additives ultimately included in the oil so as to give the required grade for the engine oil. The grade of the engine oil is, for example, that the lubricating oil composition is 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, 10W-50, 15W, 15W-20, 15W-30, or 15W-40. The oil used as the gear oil can have a viscosity of about 2 cSt to about 2000 cSt at 100 ° C.

  The base stock can be manufactured using a variety of different methods. These methods include, but are not limited to, distillation methods, solvent purification methods, hydrotreating methods, oligomerization methods, esterification methods, and repurification methods. The re-purified stock should be substantially free of material added by manufacturing, contamination, or previous use. The base oil of the lubricating oil composition of the present invention is a natural or synthetic lubricating base oil. Suitable hydrocarbon synthetic oils include, but are not limited to, an ethylene polymerization reaction or a 1-olefin polymerization reaction, or carbon monoxide and hydrogen gas to produce a polymer such as polyalphaolefin (PAO) oil. It includes oils synthesized by the hydrocarbon synthesis method used (eg, Fischer-Tropsch process). Examples of suitable base oils contain very little if any heavy fractions are present. For example, a lubricating oil fraction having a viscosity at 100 ° C. of 20 cSt or more is very small even if it exists.

  Base oils can be obtained from natural lubricating oils, synthetic lubricating oils, or mixtures thereof. Suitable base oils are produced by hydrocracking (rather than solvent extraction) aromatic and polar components in the crude product in addition to the base stock obtained by isomerization of synthetic and slack waxes. Includes decomposed base stock. Suitable base oils include those belonging to all of API categories I, II, III, IV, and V as defined in API publication 1509 (14th edition, Addendum I, December, 1998). Group IV base oils are polyalphaolefins (PAO). Group V base oils include all other base oils not included in Groups I, II, III, and IV. In this invention, Group II, III, and IV base oils are preferably used, but the base oil is produced by combining base stocks or base oils belonging to one or more of Group I, II, III, IV, and V. You can also.

  Useful natural oils include mineral lubricating oils (eg, liquid petroleum-derived oils, paraffinic, naphtha or paraffin-naphtha mixed or oil-treated mineral lubricating oils, oils obtained from coal or shale oil), Includes animal or vegetable oils (eg, rapeseed oil, castor oil, lard oil) and others.

  Useful synthetic lubricating oils include, but are not limited to, hydrocarbon oils such as polymerized or copolymerized olefins and halogen-substituted hydrocarbon oils (eg, polybutylenes, polypropylenes, propylene-isobutylene copolymers). , Chlorinated polybutylenes, poly 1-hexenes, poly 1-octenes, poly 1-decenes), and mixtures thereof; dodecyl benzenes, tetradecyl benzenes, dinonyl benzenes, di (2- Alkyl benzenes such as ethylhexyl) benzenes: polyphenyls such as biphenyls, terphenyls, alkylated polyphenyls, etc .; alkylated diphenyl ethers, alkylated diphenyl sulfides, and their derivatives, analogs, And homologs and others.

  Other useful synthetic lubricating oils are obtained by polymerizing, but not limited to, olefins having 5 or less carbon atoms (eg, ethylene, propylene, butylenes, isobutene, pentene, and mixtures thereof). Contains oil. Methods for producing such polymer oils are well known to those skilled in the art.

Another useful synthetic hydrocarbon oil comprises a liquid polymer of alpha olefins with moderate viscosity. Particularly useful synthetic hydrocarbon oils are hydrogenated liquid oligomers (eg, 1-decent trimer) of C _{6 to} C ₁₂ alpha olefins.

Another class of useful synthetic lubricating oils includes, but is not limited to, alkylene oxide polymers, i.e. homopolymers, copolymers, and derivatives thereof. These terminal hydroxyl groups may be modified, for example, by esterification or etherification. Examples of these oils are oils produced by polymerization of ethylene oxide or propylene oxide, alkyl or phenyl ethers of these polyoxyalkylene polymers (eg, methyl polypropylene glycol ether having an average molecular weight of 1000, polyethylene having a molecular weight of 500 to 1000). Diphenyl ether of glycol, diethyl ether of polypropylene glycol having a molecular weight of 1000 to 1500, or the like, or a mono- or polycarboxylic acid ester thereof (eg, acetate ester, mixed C _{3 to} C ₈ fatty acid ester), or tetraethylene glycol Including diesters of C ₁₃ with oxo acids.

  Yet another useful class of synthetic lubricating oils includes, but is not limited to, dicarboxylic acids (eg, phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacin Acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acid, alkenylmalonic acid, etc.) and various alcohols (eg, butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, And esters with 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, sebacin And diester of 2-ethylhexyl linoleic acid dimer, complex ester formed by reacting 1 mol of sebacic acid with 2 mol of tetraethylene glycol and 2 mol of 2-ethylhexanoic acid, and others.

  Esters useful as synthetic oils include, but are not limited to, carboxylic acids and alcohols having about 5 to about 12 carbon atoms (eg, methanol, ethanol, etc.), polyols, and polyol ethers (eg, neopentyl). Glycols, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, and others).

  Silicon-derived oils such as polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils constitute another useful class of synthetic lubricating oils. Specific examples of these include, but are not limited to, tetraethyl silicate, tetraisopropyl silicate, tetra (2-ethylhexyl) silicate, tetra (4-methylhexyl) silicate, tetra (p-tert-butylphenyl) silicate, hexyl. (4-methyl-2-pentoxy) disiloxane, poly (methyl) siloxanes, poly (methylphenyl) siloxanes and others.

  Lubricating oils can be obtained from unrefined, refined and rerefined oils. These oils may be natural, synthetic or a mixture of those belonging to two or more classes disclosed above. Unrefined oil is obtained from natural or synthetic raw materials (eg, coal, shale, or tar sand bitumen) without refining or processing. Examples of unrefined oils include, but are not limited to, shale oil obtained directly by a dry distillation operation, petroleum oil obtained directly by distillation, or ester oil obtained directly by an esterification process. Both of these examples are used without further processing. Refined oils are similar to unrefined oils, except that they have been treated with one or more refining steps to further improve one or more properties. Such purification techniques are known to those skilled in the art and include, for example, solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, hydrotreatment, dewaxing and the like. Rerefined oil is obtained by treating spent oil in a manner similar to that used to obtain refined oil. Such rerefined oils, also known as reclaimed oils or reprocessed oils, are often further processed by techniques to remove spent additives and oil breakdown products.

  Lubricating oil base stocks obtained by hydroisomerization of waxes may be used alone or in combination with the natural and / or synthetic base stocks described above. Such wax isomerate oil is produced by hydroisomerizing a natural or synthetic wax or a mixture thereof in the presence of a hydroisomerization catalyst.

  A typical natural wax is slack wax recovered by solvent dewaxing of mineral oil. A typical synthetic wax is a wax produced by the Fischer-Tropsch process.

  The ashless dispersant compounds used in the lubricating oil compositions of the present invention are generally used to maintain insoluble materials in the dispersion resulting from oxidation during use. Use of an ashless dispersant compound prevents sludge aggregation and precipitation or deposition on the metal surface. The lubricating oil composition of the present invention can include one or more ashless dispersants. Nitrogen-containing ashless (metal-free) dispersants are basic, and if no sulfated ash is introduced, the major base index (measured by TBN, ASTM D2896) of the lubricating composition to which they are added. It becomes an element. As used herein, the total base index (TBN) means the amount of base equivalent to milligrams of KOH per gram of sample. That is, a higher TBN index reflects more alkaline product, ie higher alkalinity. TBN was determined using the ASTM D2896 test. Ashless dispersants generally include an oil-soluble polymeric hydrocarbon backbone having functional groups. Functional groups can be attached to the particles and dispersed. Various types of ashless dispersants are known in the art.

  Exemplary ashless dispersants include, but are not limited to, a polar moiety consisting of an amine, alcohol, amide, or ester attached to the polymer backbone through a linking group. Ashless dispersants of the present invention include, for example, oil-soluble salts, esters, aminoesters, amides, imides, and oxazolines of mono- and dicarboxylic acids or their anhydrides substituted with long-chain hydrocarbons; A thiocarboxylate derivative of hydrogen, a long chain aliphatic hydrocarbon having a directly bonded polyamine; and a Mannich condensation product formed by condensing a long chain substituted phenol with formaldehyde and a polyalkylene polyamine.

  Carboxylic acid dispersants include carboxylic acid acylating agents (eg, acids, anhydrides, esters, etc.) and nitrogen-containing compounds (eg, amines), organic hydroxy compounds containing at least about 34, preferably at least about 54 carbon atoms. (For example, aliphatic compounds such as monohydric and polyhydric alcohols, or aromatic compounds including phenols and naphthols) and / or reaction products with basic inorganic substances. These reaction products include imides, amides, and esters.

  The succinimide dispersant is a kind of carboxylic acid dispersant. The succinimide dispersant is obtained by reacting a hydrocarbon-substituted succinic acylating agent with an organic hydroxy compound, an amine containing at least one hydrogen atom bonded to a nitrogen atom, or a mixture of a hydroxy compound and an amine. Generated. The term “succinic acylating agent” means a hydrocarbon-substituted succinic acid or a succinic acid-producing compound, the latter including the acid itself. Such typical materials include hydrocarbon-substituted succinic acids, anhydrides, esters (including half esters), and halides.

  Dispersants derived from succinic acid have various types of chemical structures. A succinic acid-derived dispersant belonging to one class can be represented by the following formula.

In the formula, R ¹ is independently a hydrocarbon group such as a group derived from a polyolefin. Typical hydrocarbon groups are alkyl groups such as polyisobutyl groups. Viewed another way, the R ¹ group can contain from about 40 to about 500 carbon atoms, which can be present in an aliphatic state. R ² is an alkylene group, generally an ethylene (C ₂ H ₄ ) group. Examples of succinimide dispersants include those described, for example, in US Pat. Nos. 3,172,892, 4,234,435, and 6,165,235.

  Typical polyalkenes from which substituents can be derived are homopolymers and copolymers of polymerizable olefin monomers of 2 to about 16 carbon atoms, and usually 2 to 6 carbon atoms. The amine that reacts with the succinic acylating agent to form the carboxylic acid dispersant composition may be either a monoamine or a polyamine.

  Since the succinimide dispersant usually contains a large number of nitrogen atoms in a form that functions as an imide, even though it can function as an amine in the form of amine salts, amides, imidazolines, and mixtures thereof, it is called a succinimide dispersant. When preparing succinimide dispersants, one or more succinic acid-forming substances and one or more amines are heated, usually in a substantially inert organic liquid solvent / diluent, usually to remove water. . The reaction temperature can be set from about 80 ° C. to below the decomposition temperature of the mixture or product, and is generally between about 100 ° C. and about 300 ° C. Other details and examples of methods for preparing the succinimide dispersants of the present invention include, for example, U.S. Pat. Nos. 3,172,892, 3,219,666, 3,272,746, 4,234,435, 6,165,235, and The contents described in each specification of 6440905 are included.

  Suitable ashless dispersants can include amine dispersants. The amine dispersant is the reaction product of a relatively high molecular weight aliphatic halide and an amine, preferably a polyalkylene polyamine. Examples of such amine dispersants include, for example, those described in US Pat. Nos. 3,275,554, 3,438,757, 3,454,555, and 3,565,804.

  Suitable ashless dispersants can further comprise “Mannic dispersants”. Mannich dispersants are reaction products of alkylphenols whose alkyl groups contain at least about 30 carbon atoms with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines). Examples of such dispersants include, for example, those described in US Pat. Nos. 3,306,003, 3,586,629, 3,591,598, and 3,980,569.

  A suitable ashless dispersant may be a post-treated ashless dispersant such as a post-treated succinimide. The post-treatment is, for example, treatment containing borate or ethylene carbonate, and includes, for example, those described in the specifications of US Pat. Nos. 4,612,132 and 4,746,446, or other post-treatments. The carbonated alkenyl succinimide is a polybutene having a molecular weight of about 450 to about 3000, preferably about 900 to about 2500, more preferably about 1300 to about 2300, and most preferably about 2000 to about 2400, or a mixture of these molecular weights. It is a derived polybutene succinimide. Preferably, under reactive conditions, a polybutene succinic acid derivative, an unsaturated acidic reagent copolymer of an unsaturated acidic reagent and an olefin, and, for example, US Pat. No. 5,716,912 (the contents of which are hereby incorporated by reference) Produced by reacting a mixture of polyamines as described in (incorporated herein).

  A suitable ashless dispersant may be a polymer. The polymer is a copolymer of an oil-solubilizing monomer such as decyl methacrylate, vinyl decyl ether, and a high molecular weight olefin and a monomer containing a polar substituent. Examples of polymer dispersants include those described in, for example, U.S. Pat. Nos. 3,329,658, 3,449,250 and 3,666,730.

  In a preferred embodiment of the invention, the ashless dispersant used in the lubricating oil composition is a bissuccinimide derived from polyisobutenyl groups having a number average molecular weight of about 2300 and treated with ethylene carbonate. The dispersant used in the lubricating oil composition of the present invention is preferably a non-polymer (eg, mono- or bissuccinimide).

  The ashless dispersant is generally present in the lubricating oil composition in an amount ranging from about 3 to about 10 weight percent, preferably from about 4 to about 8 weight percent, based on the total weight of the lubricating oil composition.

  At least one metal-containing detergent used in the lubricating oil composition of the present invention reduces or removes deposits as a detergent and also functions as an acid neutralizer or rust inhibitor, thereby reducing wear and corrosion. Reduce the life of the engine. The detergent generally has a polar head with a long hydrophobic tail, the polar head consisting of a metal salt of an acid organic compound.

  The lubricating oil composition of the present invention can include one or more detergents. The detergent is usually a salt, in particular an overbased salt. An overbased salt or overbased material is a single-phase, homogeneous material characterized by an excess of metal content over the stoichiometric abundance of the metal and the particular acidic organic compound that reacts with the metal. Newtonian. Overbased substances are acidic substances (typically in the presence of a stoichiometric excess of metal base and promoter in at least one inert organic solvent (eg, mineral oil, naphtha, toluene, xylene). And an inorganic acid such as carbon dioxide or a lower carboxylic acid) with a mixture containing an acidic organic compound.

  Acidic organic compounds useful for preparing overbased compositions include carboxylic acids, sulfonic acids, phosphorus-containing acids, phenols, and mixtures thereof. Preferably, the acidic organic compound is a carboxylic acid or a sulfonic acid with a sulfonic acid group or a thiosulfonic acid group (eg, a hydrocarbon-substituted benzene sulfonic acid), and a hydrocarbon-substituted salicylic acid.

  Carboxylate detergents (eg, salicylates) can be prepared by reacting an aromatic carboxylic acid with a suitable metal compound such as an oxide or hydroxide. The aromatic portion of the aromatic carboxylic acid can contain one or more heteroatoms such as nitrogen and oxygen atoms. Preferably, the aromatic moiety is only carbon atoms. More preferably, the aromatic moiety contains 6 or more carbon atoms, such as a benzene moiety. The aromatic carboxylic acid can contain one or more aromatic moieties, such as one or more benzene moieties, and may optionally be linked to each other via a fused or alkylene bond. Representative examples of aromatic carboxylic acids include salicylic acids and their sulfurized derivatives (eg, hydrocarbon substituted salicylic acid and its derivatives). For example, the sulfurization treatment of hydrocarbon-substituted salicylic acid can be performed by a method known to those skilled in the art. Salicylic acid is generally prepared by carboxylation of phenoxide (eg, Kolbe-Schmidt method). In that case, salicylic acid is usually obtained from the diluent in a mixture with uncarboxylated phenol.

  The metal salt of phenol and sulfurized phenol is prepared by reaction with a suitable metal compound such as an oxide or hydroxide. Neutral or overbased products can be obtained by methods well known in the art. For example, sulfurized phenols are produced as a mixture of compounds in which two or more phenols are joined by a sulfur-containing bond by reacting the phenol with sulfur or a hydrogen-containing compound such as hydrogen sulfide, monohalogenated sulfur, or dihalogenated sulfur. Can be prepared.

  Metal compounds useful for the production of overbased salts are generally compounds of Group I or Group II metals of the Periodic Table of Elements. Group I metals that serve as metal bases include not only Group Ia alkali metals (eg, sodium, potassium, lithium) but also Group Ib metals such as copper. The Group I metal is preferably sodium, potassium, lithium and copper, more preferably sodium or potassium, and particularly preferably sodium. Group II metals that serve as metal bases include not only Group IIa alkaline earth metals (eg, magnesium, calcium, strontium, barium) but also Group IIb metals such as zinc and cadmium. The Group II metal is preferably magnesium, calcium, barium, or zinc, more preferably magnesium or calcium, and most preferably calcium.

  Examples of overbased detergents include, but are not limited to, calcium sulfonate, calcium phenate, calcium salicylate, calcium stearate, and mixtures thereof. Overbased detergents suitable for use in the lubricating oil compositions of the present invention can be made low overbased (eg, overbased detergents having a TBN of less than about 100). The TBN of such a low overbased detergent can be about 5 to about 50, or about 10 to about 30, or about 15 to about 20. Alternatively, an overbased detergent suitable for use in the lubricating oil composition of the present invention can be highly overbased (eg, an overbased detergent having a TBN greater than about 100). The TBN of such highly overbased detergents can be about 150 to about 450, or about 200 to about 350, or about 250 to about 280. A low overbased calcium sulfonate detergent having a TBN of about 17 and a high overbased sulfurized calcium phenate having a TBN of about 400 are used for the overbased detergent used in the lubricating oil composition of the present invention. These are two representative examples. The lubricating oil composition of the present invention may contain more than one overbased detergent. The plurality of overbased detergents may all be low TBN detergents, all high TBN detergents, or a mixture of both. For example, the lubricating oil composition of the present invention may comprise a first metal-containing detergent that is an overbased alkane earth metal sulfonate detergent having a TBN of about 150 to about 450 and a superb having a TBN of about 10 to about 50. And a second metal-containing detergent that is a basic alkaline earth metal sulfonate detergent.

  Suitable detergents for the lubricating oil compositions of the present invention also include “hybrid” detergents such as, for example, phenate / salicylate, sulfonate / phenate, sulfonate / salicylate, sulfonate / phenate / salicylate and the like. Hybrid detergents include, for example, those described in US Pat. Nos. 6,153,565, 6,281,179, 6,429,178, and 6,429,179.

  The metal-containing detergent is generally in the lubricating oil composition in an amount ranging from about 0.25 to about 3% by weight, and preferably from about 0.5 to about 2% by weight, based on the total weight of the lubricating oil composition. Exists.

  The antioxidant compounds used in the lubricating oil composition of the present invention reduce the tendency of the base stock to degrade during use. Such degradation is evidenced by the formation of oxides such as sludge and varnish deposits on metal surfaces and increased viscosity. Such antioxidants include hindered phenols, ashless oil-soluble phenates and sulfurized phenates, alkyl-substituted diphenylamines, alkyl-substituted phenyl and naphthylamines, and the like, and mixtures thereof. Suitable diphenylamine antioxidants include, but are not limited to, monoalkylated diphenylamine, dialkylated diphenylamine, trialkylated diphenylamine, and the like, and mixtures thereof. Examples of representative diphenylamine antioxidants include butyldiphenylamine, dibutyldiphenylamine, octyldiphenylamine, dioctyldiphenylamine, nonyldiphenylamine, dinonyldiphenylamine, t-butyl-t-octyldiphenylamine and the like, and mixtures thereof.

  The antioxidant compound is generally present in the lubricating oil composition in an amount ranging from about 0.2 to about 4 weight percent, and preferably from about 0.3 to about 1 weight percent, based on the total weight of the lubricating oil composition. Exists.

  Antiwear agents other than the zinc dialkyldithiophosphate compounds used in the lubricating oil composition of the present invention include, for example, molybdenum-containing complexes such as molybdenum / nitrogen-containing complexes. Such complexes are known in the art and are described, for example, in US Pat. No. 4,263,152. The contents of this specification are incorporated herein for reference.

The structure of the molybdenum / nitrogen complex is certainly not known. However, a molybdenum / nitrogen complex is one in which the valence of molybdenum is saturated with oxygen or sulfur atoms and the molybdenum is one or more nitrogens of the basic nitrogen-containing compound used in the preparation of the composition as in the present invention. It is believed to be a compound that forms a complex with an atom or is in a salt state. The molybdenum compounds used in the preparation of molybdenum and molybdenum / nitrogen complexes are acidic molybdenum compounds. Acidity means that the molybdenum compound can react with the basic nitrogen compound as measured by the titration procedure of ASTM test D-664 or D-2896. Typically, these molybdenum compounds are hexavalent. Suitable molybdenum compounds include molybdate, ammonium molybdate, sodium molybdate, potassium molybdate, and other alkali metal molybdates, and other molybdates such as hydrogen salts (eg, sodium hydrogen molybdate), MoOCl ₄ , MoO ₂ Br ₂ , Mo ₂ O ₃ Cl ₆ , molybdenum trioxide and others and mixtures thereof. Preferred acidic molybdenum compounds are molybdic acid, ammonium molybdate, and alkali metal molybdate. Particularly preferred are molybdic acid and ammonium molybdate.

  The basic nitrogen-containing compound used to prepare the molybdenum / nitrogen complex contains at least one basic nitrogen atom and is preferably oil-soluble. Representative examples of basic nitrogen-containing compounds include succinimide, carboxylic acid amide, hydrocarbon monoamine, hydrocarbon polyamine, Mannich base, phosphoric acid amide, thiophosphoric acid amide, phosphonic acid amide, dispersible viscosity index improver, and others. Including mixtures thereof. Any nitrogen-containing compound can be post-treated, for example with boron. The post-treatment can employ methods well known in the art as long as the composition continues to contain basic nitrogen atoms. Post-treatment is particularly suitable for compositions of succinimide and Mannich base.

  Succinimides that can be used to prepare the molybdenum complexes described herein are described in numerous references and are well known in the art. Related substances included in the technical terms of several basic succinimides and “succinimides” are described in US Pat. Nos. 3,172,892, 3,219,666, and 3,272,746. The contents of each specification are incorporated herein for reference. The term “succinimide” is understood to include numerous types of amides, imides, and amidines that can be prepared simultaneously by those skilled in the art. However, the major product is succinimide, and this term is generally taken to mean the reaction product of an alkenyl-substituted succinic acid or anhydride and a nitrogen-containing compound. A preferred succinimide is a succinimide prepared from a hydrocarbon succinic anhydride and ethyleneamine because commercial products are available. The hydrocarbon group of the hydrocarbon succinic anhydride contains from about 24 to about 350 carbon atoms. Examples of ethyleneamine include ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine and others. Particularly preferred are succinimides prepared from polyisobutenyl succinic anhydride having from about 70 to about 128 carbon atoms and tetraethylenepentamine or triethylenetetraamine and mixtures thereof.

  Included in the term “succinimide” is a hydrocarbon succinic acid or anhydride and a poly secondary amine containing at least one tertiary amino nitrogen atom in addition to two or more secondary amino groups. It is an oligomer. This composition generally has an average molecular weight of about 1500 to about 50,000. A typical compound would be a compound prepared by reaction of polyisobutenyl succinic anhydride with ethylene dipiperazine.

Carboxamide compounds are also suitable starting materials for the preparation of molybdenum complexes. Examples of such compounds include, for example, those disclosed in US Pat. No. 3,405,064. The contents of this specification are incorporated herein for reference. These compounds are generally prepared by reacting a carboxylic acid, its anhydride, or ester thereof with an amine such as ethyleneamine or a hydrocarbon polyamine to produce a mono- or polycarboxylic amide. The carboxylic acid, anhydride, or ester thereof has at least about 12 to about 350 aliphatic carbon atoms in the aliphatic backbone and sufficient side chains to make the molecule oil-soluble if necessary. Has an aliphatic group. Preferably, these amines are (1) a carboxylic acid of the formula R ¹ COOH (R ¹ is a C _{12 to} C ₂₀ alkyl group) or a polyisobutenyl carboxylic acid (polyisobutenyl group is about 72 to about 128). And (2) ethyleneamine, especially triethylenetetraamine, tetraethylenepentamine, or a mixture thereof.

  Another class of basic nitrogen compounds useful for the preparation of molybdenum / nitrogen complexes are hydrocarbon monoamines and hydrocarbon polyamines. Examples of these are disclosed in US Pat. No. 3,574,576. The contents of this specification are incorporated herein for reference. The hydrocarbon group (eg, an alkyl group or an olefinic group having one or two unsaturation positions) usually has from about 9 to about 350 carbon atoms, preferably from about 20 to about 200 carbon atoms. Particularly preferred hydrocarbon polyamines are, for example, polyalkylene polyamines such as polyisobutenyl chloride and ethyleneamine (eg, ethylenediamine, diethylenetriamine, tetraethylenepentamine, 2-aminoethylpiperazine, 1,3-propylenediamine, 1,2-propylene). It is obtained by reacting with a diamine or the like).

Another class of basic nitrogen compounds useful for supplying basic nitrogen are Mannich base compounds. Such compounds are prepared from phenol or C _{9 to} C ₂₀₀ alkylphenols, aldehydes such as formaldehyde or formaldehyde precursors such as paraformaldehyde, and amine compounds. The amine may be a monoamine or a polyamine. Typical compositions are prepared from alkylamines such as methylamine or ethyleneamine (eg, diethylenetriamine or tetraethylenepentamine) and others. Phenolic material may be sulfurized and preferably alkylphenol dodecylphenol or C ₈₀ to C _100. Representative Mannich bases are disclosed in US Pat. Nos. 3,368,972, 3,539,663, 3,649,229, and 4,157,309. The contents of each specification are incorporated herein for reference. Mannich bases can be prepared by reacting an alkylphenol having at least about 50 carbon atoms, preferably from about 50 to about 200 carbon atoms, with formaldehyde and an alkylene polyamine of H ₂ N (ANH) _e H. Where A is a divalent saturated alkyl hydrocarbon of from about 2 to about 6 carbon atoms and e is from 1 to about 10. The condensation product of the alkylene polyamine may be further reacted with urea or thiourea. The usefulness of these Mannich bases as starting materials for preparing lubricating oil additives can be significantly improved by treating the Mannich base using general techniques and introducing boron into the compound. Many.

The molybdenum-containing complex may be sulfided or not sulfided. Typical sulfur sources for preparing molybdenum / sulfur complexes are sulfur, hydrogen sulfide, sulfur monochloride, sulfur dichloride, phosphorus pentasulfide, R ² S _f (R ² is a C _{1 to} C ₄₀ alkyl, etc. Hydrocarbon groups, and f is at least 2), inorganic sulfides and polysulfides such as (NH ₄ ) ₂ S _g (g is at least 1), thioacetamide, thiourea, and the formula R ² SH ( R ² includes mercaptans as defined above. Also useful as sulfurizing agents are traditional sulfur-containing antioxidants such as sulfurized waxes and polysulfides, sulfurized olefins, sulfurized carboxylic acids and esters and sulfurized ester-olefins, and sulfurized alkylphenols and their metal salts.

  Molybdenum / nitrogen-containing complexes can generally be prepared using an organic solvent containing a polarity promoter in the complexing stage. Regarding the preparation of such a complex, for example, U.S. Pat. Nos. 4,259,194, 4,259,195, 4,261,843, 4,263,152, 4,265,773, 4,283,295, 4,285,822, No. 4,369,119, No. 4,370,246, No. 4,394,279, No. 4,402,840, No. 6,682,896, and US Patent Application Publication No. 2005/0209111. The contents of each specification are incorporated herein for reference. As described in these specifications, the molybdenum / nitrogen containing complexes can be further sulfurized.

  In some embodiments, the antiwear compound used herein is substantially free of phosphorus and / or sulfur content. In another aspect, the antiwear compound used herein is free of phosphorus and / or sulfur content.

  The antiwear compound other than the zinc dialkyldithiophosphate compound is generally about 0.25 to about 5% by weight and preferably about 0.3 to about 5% by weight, based on the total weight of the lubricating oil composition in the lubricating oil composition. Present in an amount ranging from 2% by weight.

  The lubricating oil composition of the present invention comprises an ashless dispersant, at least one metal-containing detergent, an antioxidant, and an antiwear agent other than a zinc dialkyldithiophosphate compound, optionally using other additives, It can be suitably produced by simply blending or mixing with oil having a lubricating viscosity. Also, in order to facilitate the formulation of a lubricating oil composition containing an additive of a desired concentration, an anti-wear agent other than an ashless dispersant, a metal-containing detergent, an antioxidant, and a zinc dialkyldithiophosphate compound is added. It may be pre-formulated as a concentrate or package in an appropriate ratio with various other additives. Ashless dispersants, at least one metal-containing detergent, antioxidants, and anti-wear agents other than zinc dialkyldithiophosphate compounds provide improved wear resistance and dissolve in oil in the desired formulated lubricant. And in a concentration that can be mixed with other additives. Compatibility in this case generally means that the compound, which is oil-soluble to some extent at the applicable processing ratio, does not precipitate other additives under normal conditions. Suitable oil solubility / compatibility ranges in certain compound lubricating oil formulations can be determined using routine solubility testing methods by those having ordinary skill in the art. For example, lubricating oil compositions formulated at ambient conditions (approximately 20 ° C. to 25 ° C.), either by actual precipitation from the oil composition or by formulation of a “cloudy” solution that is evidence of insoluble wax particle formation. Precipitation can be measured.

  The lubricating oil composition of the present invention may further contain known additives to add additional auxiliary functions, so that the final lubricating oil composition in which these additives are dispersed or dissolved is added. can get. For example, lubricating oil compositions include friction modifiers, rust inhibitors, antifogging agents, demulsifiers, metal deactivators, pour point depressants, defoamers, auxiliary solvents, package compatibilizers, corrosion inhibitors, dyes. , Extreme pressure agents, etc., and mixtures thereof. Various additives are known and are commercially available. Additives and their similar compounds can be used in the preparation of the lubricating oil composition of the present invention by common compounding methods.

Examples of friction modifiers include, but are not limited to, alkoxylated aliphatic amines; boronated aliphatic epoxides; aliphatic phosphorous acid, aliphatic epoxides, aliphatic amines, boronated alkoxylated aliphatic amines, fatty acids Metal salts, fatty acid amides, glycerol esters, boronated glycerol esters; and aliphatic imidazolines as disclosed in US Pat. No. 6,372,696, the contents of which are incorporated herein by reference. Obtained from the reaction product of a fatty acid ester of C _{4 to} C ₇₅ , preferably C _{6 to} C ₂₄ , most preferably C _{6 to} C ₂₀ and a nitrogen-containing compound selected from the group consisting of ammonia and alkanolamines. Other friction modifiers, and mixtures thereof. The friction modifier is in the lubricating oil composition from about 0.02 to about 2.0%, preferably from about 0.05 to about 1.0%, more preferably from about 0.1 to about 2.0% by weight of the lubricating oil composition. It can be added in an amount in the range of about 0.5% by weight.

  Examples of the rust inhibitor include, but are not limited to, nonionic polyoxyalkylene agents (eg, polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, Polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate); stearic acid and other fatty acids; dicarboxylic acids; metal soap Fatty acid amine salt; metal salt of strong sulfonic acid; partial carboxylic acid ester of polyhydric alcohol; phosphate ester; (short chain) alkenyl succinic acid; partial ester thereof And their nitrogen-containing derivatives, synthetic alkaryl sulfonic acids (e.g., dinonyl naphthalene sulfonic acid metal salts) and the like; and mixtures thereof.

  Examples of antifoaming agents include, but are not limited to, polymers of alkyl methacrylate; polymers of dimethyl silicone, and the like, and mixtures thereof.

  The lubricating composition of the present invention can also contain a viscosity index improver. Examples of viscosity index improvers include poly (alkyl methacrylate), ethylene-propylene copolymer, styrene-butadiene copolymer, and polyisoprene. Dispersed (increased dispersibility) or multifunctional viscosity index improvers are also used. These viscosity index improvers can be used alone or in combination. The amount of viscosity index improver blended into the engine oil will vary depending on the desired blended engine oil viscosity, but is generally in the range of about 0.5 to about 20 weight percent based on the total amount of engine oil.

  The lubricating oil composition of the present invention has a wear reduction function that is superior to a corresponding composition in which a dihydrocarbyl zinc phosphate such as a zinc dialkyldithiophosphate compound is present in the lubricating oil composition. In certain embodiments of the present invention, the lubricating oil composition of the present invention has a friction at least about 20% greater than a corresponding composition in which a zinc dihydrocarbyl phosphate such as a zinc dialkyldithiophosphate compound is present in the lubricating oil composition. Has a mitigation function. In another aspect of the present invention, the lubricating oil composition of the present invention has a friction reducing function that is at least about 25% greater than a corresponding composition in which a zinc dialkyldithiophosphate compound is present in the lubricating oil composition.

  The final application fields of the lubricating oil composition of the present invention include, for example, marine cylinder lubricating oils used in crosshead diesel engines, automobile and railway crankcase lubricating oils, heavy machinery (for example, steelworks) lubricating oils, and the like. Or bearing grease etc. are possible. In certain embodiments, a lubricating oil composition of the present invention is compressed with a compression ignition diesel engine (eg, a durable diesel engine or exhaust gas recirculation (EGR) system; a catalytic converter; and a compression ignition diesel engine fitted with at least one particulate trap). Used to lubricate internal combustion engines such as

  Whether the lubricating oil composition is liquid or solid generally depends on the presence or absence of a thickener. Exemplary thickeners include polyurea acetate, lithium stearate, and others.

  The invention will be further described in the following examples, which are not intended to limit the invention.

[Example 1]
3.858% by weight of bissuccinimide prepared from polyisobutenyl succinic anhydride having an average molecular weight of 2300 and heavy polyamine and post-treated with ethylene carbonate, 0.286% by weight of boronized monooleate glycerol friction modifier, molybdenum succinimide 0.487% by weight of a dispersant / antiwear agent, 0.490% by weight of diphenylamine antioxidant, 0.593% by weight of 17TBN calcium sulfonate detergent, 1.141% by weight of 410TBN calcium sulfonate detergent, derived from silicone Lubricating oil containing 0.050% by mass of antifoaming agent, 0.537% by mass of Exon 100N diluent oil and 4.800% by mass of an ethylene-propylene copolymer viscosity index improver in 87.46% by mass of Group II base oil A composition was prepared. The resulting lubricating oil composition had a phosphorus content of 0% by mass and a sulfur content of 0.051% by mass.

[Comparative Example A]
To the lubricating oil composition of Example 1, 0.64% by weight zinc dihydrocarbyl dithiophosphate was added. The resulting lubricating oil composition had a phosphorus content of 0.048% by mass and a sulfur content of 0.151% by mass.

[Comparative Example B]
2.35% by weight of succinimide dispersant, 6% by weight of boronated succinimide dispersant, 2.84% by weight of 260 TBN calcium phenate detergent, 1.02% by weight of 17 TBN calcium sulfonate detergent, 410 TBN of calcium sulfonate detergent 0.22 wt%, diphenylamine antioxidant 0.3 wt%, hindered phenol antioxidant 0.6 wt%, bissuccinimide terephthalate dispersant 0.4 wt% (manufactured from 1300 MW PIBSA and heavy polyamine) %, Molybdenum succinimide complex dispersant / antiwear agent 0.5% by mass, antifoaming agent 10 ppm, functional group-containing viscosity index improver 5.75% by mass, pour point depressant 0.3% by mass, functional group 0.75% by weight of a viscosity index improver having no dihydrocarbyl dithiophosphate 1.89% by weight of lead, 24.5% by weight of Group II base oil having a kinematic viscosity (kv) at 100 ° C. of 4.7 to 4.9 cSt, and kv at 100 ° C. of 7.8 to 7.9 cSt A lubricating oil composition contained in 76.17% by mass of base oil consisting of 75.5% by mass of Group II base oil was prepared. The resulting lubricating oil composition had a phosphorus content of 0.150% by mass and a sulfur content of 0.445% by mass.

[test]
(Mini traction machine evaluation)
The lubricating oil composition of Example 1 and the lubricating oil compositions of Comparative Examples A and B were evaluated using a mini-traction machine (MTM) bench test (PCS Instruments, London, UK). The PCS MTM device was modified to replace the pin holder that was associated with the device with a 1/4 inch test ball made of Farex 52100 steel (along with a special holder) (eg, Yamaguchi, ES. "Measurement of friction and wear using a modified MTM tribometer", IP Com Journal 7, 2, 9, 57-58 (August 2002), IPCOM No. 0000009117D; and Yamaguchi, ES, (See “Wear due to soot in diesel engine”, Journal of Friction Engineering, Journal of Mechanical Engineering, Part J, Volume 220, J5, pages 463-469 (2006)). The device was used in a pin-on-disk manner and operated under sliding conditions. The ball was held firmly in a special holder so that the ball stayed underneath as the disc slid. The conditions are shown in Table 1.

Table 1 ────────────────────
MTM test conditions ────────────────────
Load 14N
Initial contact pressure 1.53 GPa
116 ° C
Friction combination 52100/52100
────────────────────
Speed mm / sec min ────────────────────
3800 10
2000 10
1000 10
100 10
20 10
10 10
5 10
────────────────────
Adjuster length at ignition 70 minutes Diesel engine soot 9%
────────────────────

  Engine soot from the engine test facility overhead recovery unit was used for this test. Mineral oil was added to the soot before removal. Soot must be cleaned before testing. The soot was made into a thin slurry using pentane. The slurry was stirred for several minutes before being filtered through Wattsman No. 2 filter paper on a Buchner funnel. The precipitate was again made into a thin slurry and again filtered through Wattsman No. 2 filter paper. The precipitate was then dried in a vacuum oven at 20 inches of vacuum and 90 ° C. over 16 hours. The dried soot was then passed through a 50 mesh (up to 300 μm) sieve before use. The purpose of this operation is to remove oil and other impurities, thereby forming reproducible particles and increasing abrasive wear due to particles as found in modern exhaust gas recirculation (EGR) engines. .

To prepare the test sample, the corrosion resistant coating was removed from _a PCS Instruments 52100 smooth (0.02 micron _Ra ) steel disc using heptane, hexane, and isooctane. The disc was then wiped clean with a soft tissue and submerged in a beaker containing a cleaning solvent until the coating on the disc track was removed and the disc track appeared shiny. The disc and test ball were placed in separate containers and immersed in chevron 450 thinner. Finally, the test sample was placed in a sonicator and subjected to ultrasonic cleaning for 30 minutes.

  The result of this evaluation is shown in FIG. FIG. 1 shows the wear scar diameter (WSD) and standard deviation (STD) for the lubricating oil compositions of Example 1 and Comparative Examples A and B. As the data show, the lubricating oil composition of Example 1 without zinc dihydrocarbyl dithiophosphate is significantly better compared to the lubricating oil composition of Comparative Example A treated with zinc dihydrocarbyl dithiophosphate. Abrasion resistance was shown. This is an unexpected result given that zinc dihydrocarbyl dithiophosphate is a known antiwear agent and is expected to improve the antiwear properties of lubricating oil compositions. Indeed, the MTM wear in the lubricating oil composition of Example 1 has been lower than the lubricating oil composition of Comparative Example B, which contains a relatively large amount of relatively large amounts of zinc dihydrocarbyl dithiophosphate.

  Various modifications can be made to the aspect disclosed herein. Accordingly, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. For example, the functions performed above and as the best mode for carrying out the invention are for illustrative purposes only. Other modifications and schemes may be implemented by those skilled in the art without departing from the scope and spirit of the present invention. Further, those skilled in the art will be able to make other modifications within the scope and spirit of the claims appended hereto.

Claims (15)

  A lubrication comprising (a) an oil having a major amount of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent, (d) an antioxidant, and (e) an antiwear agent. An oil composition, wherein the lubricating oil composition is free of zinc dialkyldithiophosphate compounds and is substantially free of phosphorus.   The lubricating oil composition of claim 1, wherein the ashless dispersant is a bissuccinimide derived from one or more polyalkylene succinic anhydrides.   The lubricating oil composition of claim 2, wherein the polyalkylene group is a polyisobutenyl group having an average molecular weight of about 900 to about 2300.   The lubricating oil composition of claim 3, wherein the bissuccinimide is post-treated with ethylene carbonate.   The lubricating oil composition of claim 1, wherein the at least one metal-containing detergent is an overbased alkal earth metal sulfonate detergent having a total base number (TBN) of from about 10 to about 450.   The lubricating oil composition of claim 1, wherein the at least one metal-containing detergent comprises two metal-containing detergents.   The two metal-containing detergents are a first metal-containing detergent that is an overbased alkal earth metal sulfonate detergent having a TBN of about 150 to about 450 and an overbased alkal having a TBN of about 10 to about 50. The lubricating oil composition of claim 6 comprising a second metal-containing detergent that is an earth metal sulfonate detergent.   The lubricating oil composition of claim 1, wherein the antioxidant is a diphenylamine compound.   The lubricating oil composition of claim 1, wherein the antiwear agent comprises a molybdenum-containing complex.   The lubricating oil composition of claim 9, wherein the molybdenum-containing complex is a molybdenum / nitrogen complex. About 3% to about 10% by weight of an ashless dispersant relative to the total weight of the lubricating oil composition;
From about 0.5% to about 2% by weight of at least one metal-containing detergent based on the total weight of the lubricating oil composition;
From about 0.2% to about 1% by weight of antioxidants relative to the total weight of the lubricating oil composition; and from about 0.1% to about 2% of antiwear agents relative to the total weight of the lubricating oil composition; The lubricating oil composition of claim 1 comprising:   The lubricating oil composition of claim 1, further comprising at least one additive selected from the group consisting of friction modifiers, extreme pressure agents, viscosity index improvers, pour point depressants, and mixtures thereof.   The lubricating oil composition of claim 1, having a wear reducing function that is at least about 20% greater than a corresponding composition in which the zinc dihydrocarbyl dithiophosphate compound is present in the lubricating oil composition.   The lubricating oil composition of claim 1, having a wear reduction function that is at least about 25% greater than a corresponding composition in which the zinc dihydrocarbyl dithiophosphate compound is present in the lubricating oil composition.   15. A method for reducing wear in an internal combustion engine, comprising operating the internal combustion engine with a lubricating oil composition according to claims 1-14.

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