JP5258143B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition, and more particularly, to a lubricating oil composition that is suitably used for applications such as a lubricating oil for an internal combustion engine.

  In the field of lubricating oils used in internal combustion engines and automatic transmissions, demands for longer drains of lubricating oils are increasing further from the viewpoint of effective resource utilization, reduction of waste oil, and cost reduction of lubricating oil users in recent years. Yes.

  Therefore, in the conventional lubricating oil, in order to meet the above-mentioned requirements, a mineral oil (highly refined mineral oil) whose aromatic content has been reduced by highly refined treatment is used as a base oil, and this is a hindered phenol type having a t-butyl group. Or by containing a large amount of a reaction chain terminator such as an amine-based antioxidant or a sulfur-containing compound having a peroxide resolution such as zinc dithiophosphate (ZDTP) or molybdenum dithiocarbamate (MoDTC), the antioxidant property of the lubricating oil Improvements are being made.

  However, there is a limit in maintaining the oxidation stability by increasing the amount of the reaction chain terminator, and there is a problem that the degradation product of the reaction chain terminator becomes insoluble. In addition, sulfur-containing compounds such as ZDTP can themselves be oxidized or thermally decomposed to produce acidic substances such as sulfuric acid as a price for decomposing peroxides. In lubricating oil for internal combustion engines and the like in which an ash dispersant is blended, it causes a decrease in base number and high temperature cleanliness, which are indicators of acid neutralization characteristics.

  On the other hand, in order to suppress the accumulation of ash on an internal combustion engine piston, a catalyst such as a three-way catalyst, an oxidation catalyst, a NOx occlusion reduction catalyst, or an exhaust gas purification device such as DPF, a metal in lubricating oil is generally used. Although it is necessary to reduce the blending amount of the system detergent, simply reducing the blending amount of the metal detergent will impair the acid neutralization characteristics and the high temperature cleanability.

  Further, with respect to the above-mentioned catalyst, particularly a NOx occlusion reduction type catalyst, in order to reduce poisoning by sulfur, the fuel is reduced in sulfur (for example, light oil having a sulfur content of 50 mass ppm or less, gasoline having a sulfur content of 10 mass ppm or less, etc.). However, in an internal combustion engine using such a low sulfur fuel, the influence of the sulfur content in the lubricating oil on the catalyst becomes relatively large. Therefore, further increase of the sulfur-containing compound in the lubricating oil is not preferable, and it is important to reduce the sulfur content in the lubricating oil.

In view of this, studies have been made to solve the problems in the conventional lubricating oil and achieve a sufficiently long drain. For example, Patent Document 1 includes a lubricating oil composition containing a specific phosphorus compound, and Patent Document 2 includes a lubricating oil composition that reduces the content of ZDTP and uses salicylate, sulfonate, and a phosphorus-containing antiwear agent in combination. However, Patent Document 3 discloses a lubricating oil composition in which a specific phosphorus compound and a sulfur-containing organic molybdenum complex are used in combination.
JP 2002-294271 A JP 2003-277781 A JP 2004-83891 A

  The lubricating oil compositions described in Patent Documents 1 to 3 can achieve a significantly longer drain than conventional lubricating oils containing ZDTP, but according to the study by the present inventors. Even in these lubricating oil compositions, there is still room for improvement in order to improve all of the antioxidant property, the base number maintenance property, the high temperature cleanability and the resistance to NOx in a well-balanced and sufficient manner.

  The present invention has been made in view of such circumstances, and can achieve a high level of anti-oxidation property, base number maintenance property, high-temperature cleanability, and resistance to NOx in a well-balanced manner, and particularly resistance to NOx. An object of the present invention is to provide a lubricating oil composition that is excellent and capable of realizing a high level of long drain in applications such as lubricating oil for internal combustion engines.

  As a result of intensive studies to achieve the above object, the present inventor has found that the above problems can be solved by a lubricating oil composition using an organic molybdenum compound and a specific aromatic compound in combination. It came to be completed.

［式中、Ａは芳香族環を示し、ＸはＳＨ基又はＯＨ基を示し、Ｒは炭素数４〜３０の直鎖状又は分枝状のアルキル基（但し、ｔｅｒｔ−ブチル基を除く）を示し、ａは１以上の整数を示し、Ａが芳香族炭素環のときｂは１以上の整数を示し、Ａが芳香族複素環のときｂは０又は１以上の整数を示す。］ That is, the lubricating oil composition of the present invention is characterized by containing a lubricating base oil, an organic molybdenum compound, and an aromatic compound having a structure represented by the following general formula (1).

[In the formula, A represents an aromatic ring, X represents an SH group or OH group , and R represents a linear or branched alkyl group having 4 to 30 carbon atoms (excluding a tert-butyl group). A represents an integer of 1 or more, b represents an integer of 1 or more when A is an aromatic carbocycle, and b represents an integer of 0 or 1 when A is an aromatic heterocyclic ring. ]

  In the present invention, the “aromatic ring” includes both aromatic carbocycles and aromatic heterocycles.

  In the lubricating oil composition of the present invention, the combined use of the organic molybdenum compound and the aromatic compound represented by the above general formula eliminates the need to combine a sulfur-containing peroxide decomposer or a specific metal detergent. In addition, the antioxidant property, the base number maintaining property, the high-temperature cleanability and the resistance to NOx can be achieved at a high level in a well-balanced manner, and in particular, the resistance to NOx can be dramatically improved.

  Further, the lubricating oil composition of the present invention can be suitably used for an internal combustion engine in which a low sulfur fuel, particularly a fuel having a sulfur content of 100 mass ppm or less is used. That is, in an internal combustion engine using such a low-sulfur fuel, the SOx content in the combustion gas can be reduced, and sulfur poisoning to a catalyst such as an oxidation catalyst, a three-way catalyst, or a NOx occlusion reduction catalyst is reduced. In addition, the deterioration of the lubricating oil can be suppressed by reducing the SOx content in the lubricating oil. Therefore, if the lubricating oil composition of the present invention, which can be reduced in sulfur compared with the conventional ZDTP blended oil, sulfur poisoning to the catalyst derived from the lubricating oil can be further reduced, and oxidation stability , Base number maintenance, high temperature cleanliness and resistance to NOx can all be achieved at a very high level, and therefore the advantages of using the lubricating oil composition of the present invention and the low sulfur fuel in an internal combustion engine. (Exhaust gas purification, longer life of the catalyst, longer drain of the lubricating oil, cost / waste oil reduction and resource saving based on them) can be maximized.

  In the lubricating oil composition of the present invention, the organic molybdenum compound preferably does not contain sulfur as a constituent element. By using such an organic molybdenum compound, it is possible to achieve a higher level of long drainage.

  In the lubricating oil composition of the present invention, the sulfur content of the lubricating base oil is preferably 0.005% by mass or less based on the total amount of the lubricating base oil. By using a lubricating base oil having a sulfur content of 0.005% by mass or less, the above-described effects of the present invention can be achieved at a higher level.

  The “sulfur content” in the present invention means a value measured in accordance with JIS K 2541-4 “Radiation Excitation Method” (usually in a range of 0.01 to 5% by mass). The content of an additive containing sulfur as an element in terms of elemental sulfur was measured by measuring [the sulfur content of the entire lubricating oil composition] and [the sulfur content derived from the lubricating base oil and diluent], respectively. It is obtained by subtracting the latter measured value from the measured value. In addition, as a method for directly obtaining the sulfur content of an additive containing sulfur as a constituent element, the active ingredient of the additive is separated from the lubricating oil and the diluent oil, and JIS K 2541-5 “bomb type is used for the active ingredient. There is a method for measuring the sulfur content in accordance with the “mass method, appendix (normative), inductively coupled plasma emission method” (usually 0.05 mass% or more).

  The active ingredient in the lubricating oil composition or additive can be separated from the lubricating base oil and diluent oil by a conventional method such as rubber membrane dialysis. In addition, when the sulfur content is below the normal measurement limit of the above method, it can be easily obtained from a calibration curve obtained by measurement in which the concentration of the standard substance is appropriately changed.

  According to the present invention, it is possible to achieve a high level of good balance between antioxidant properties, base number maintenance, high temperature cleanability and resistance to NOx, and in particular, a sulfur-containing peroxide decomposer effective for resistance to NOx. Even if it is not used, and it is not used in combination with a specific metal-based detergent as in Patent Document 2, it is very excellent in resistance to NOx. Therefore, even when the lubricating oil composition of the present invention is used for an internal combustion engine using a low sulfur fuel, an internal combustion engine equipped with an exhaust gas purification device, or an internal combustion engine (such as a gas engine) having a high NOx concentration, Excellent long drain performance, especially in internal combustion engines using low-sulfur fuel and equipped with exhaust gas purification devices (merits of exhaust gas purification, longer catalyst life and long drain of lubricating oil) As well as cost / waste oil reduction and resource saving based on them).

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The lubricating base oil used in the present invention is not particularly limited, and a mineral base oil or a synthetic base oil used for ordinary lubricating oil can be used.

  Specifically, as the mineral base oil, the lubricating oil fraction obtained by subjecting the crude oil to atmospheric distillation obtained under reduced pressure is subjected to solvent removal, solvent extraction, hydrocracking, Examples include those refined by performing one or more treatments such as solvent dewaxing, hydrorefining, etc., or base oils produced by a method of isomerizing wax isomerized mineral oil, GTL WAX (Gas Liquid Wax).

  Further, the sulfur content in the mineral oil base oil is not particularly limited, but is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and 0.01% by mass or less. More preferably, it is particularly preferably 0.005% by mass or less. By reducing the sulfur content of the mineral oil base oil in this way, it is superior in long draining properties, and when used as a lubricating oil for internal combustion engines, it has low sulfur that can avoid adverse effects on exhaust gas aftertreatment devices as much as possible. A lubricating oil composition can be obtained.

  Specific examples of synthetic base oils include polybutene or hydrides thereof; poly-α-olefins such as 1-octene oligomers and 1-decene oligomers or hydrides thereof; ditridecyl glutarate, di-2-ethylhexyl adipate , Diisodecyl adipate, ditridecyl adipate, and di-2-ethylhexyl sebacate, etc .; neopentyl glycol ester, trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, and pentaerythritol Examples thereof include polyol esters such as pelargonate; aromatic synthetic oils such as alkyl naphthalene, alkyl benzene, and aromatic esters, or mixtures thereof.

  In the present invention, one of the mineral base oil and the synthetic base oil may be used alone, or two or more kinds may be used in combination. Mixed base oils that combine two or more types of lubricating base oils include mixed base oils of two or more mineral base oils, mixed base oils of two or more synthetic base oils, and one or more mineral oil bases A mixed base oil of oil and one or more synthetic base oils is included.

The kinematic viscosity of the lubricating base oil is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 20 mm ² / s or less, more preferably 10 mm ² / s or less. On the other hand, the kinematic viscosity is preferably 1 mm ² / s or more, more preferably 2 mm ² / s or more. When the kinematic viscosity at 100 ° C. of the lubricating base oil exceeds 20 mm ² / s, the low-temperature viscosity characteristic deteriorates. On the other hand, when the kinematic viscosity is less than 1 mm ² / s, an oil film is formed at the lubrication site. Insufficient lubrication results in poor lubricity and increases the evaporation loss of the lubricating base oil, which is not preferable.

  Further, the evaporation loss amount of the lubricating base oil is preferably 20% by mass or less, more preferably 16% by mass or less, and particularly preferably 10% by mass or less in terms of NOACK evaporation. When the NOACK evaporation amount of the lubricating base oil exceeds 20% by mass, not only the evaporation loss of the lubricating oil is large, but also when used as a lubricating oil for internal combustion engines, the sulfur compound, phosphorus compound, or metal content in the composition May accumulate in the exhaust gas purification device together with the lubricating base oil, and there is a concern about the adverse effect on the exhaust gas purification performance. Here, the NOACK evaporation amount is measured in accordance with ASTM D5800.

  Further, the viscosity index of the lubricating base oil is not particularly limited and is usually 200 or less, but the value is preferably 80 or more, so that excellent viscosity characteristics from low temperature to high temperature can be obtained, and 100 or more. More preferably, it is more preferably 120 or more. When the viscosity index of the lubricating base oil is less than 80, the low temperature viscosity characteristics tend to deteriorate. The viscosity index of the lubricating base oil is preferably 160 or less.

  The organic molybdenum compound used in the present invention may be a sulfur-containing molybdenum compound such as molybdenum dithiocarbamate, but is preferably an organic molybdenum compound that does not contain sulfur as a constituent element.

  Specific examples of organic molybdenum compounds that do not contain sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, and molybdenum salts of alcohols. Complexes, molybdenum salts of organic acids and molybdenum salts of alcohols are preferred.

Examples of the molybdenum compound constituting the molybdenum-amine complex include molybdenum trioxide or a hydrate thereof (MoO ₃ · nH ₂ O), molybdic acid (H ₂ MoO ₄ ), and an alkali metal molybdate (M ₂ MoO ₄ ; M Represents an alkali metal), ammonium molybdate ((NH ₄ ) 2 MoO ₄ or (NH ₄ ) ₆ [Mo ₇ O ₂₄ ] · 4H ₂ O), MoCl ₅ , MoOCl ₄ , MoO ₂ Cl ₂ , MoO ₂ Br ₂ And molybdenum compounds containing no sulfur such as Mo ₂ O ₃ Cl ₆ . Among these molybdenum compounds, hexavalent molybdenum compounds are preferable from the viewpoint of the yield of the molybdenum-amine complex. Further, from the viewpoint of availability, among the hexavalent molybdenum compounds, molybdenum trioxide or a hydrate thereof, molybdic acid, alkali metal molybdate, and ammonium molybdate are preferable.

  The amine compound constituting the molybdenum-amine complex is not particularly limited, and specific examples of the nitrogen compound include monoamines, diamines, polyamines, and alkanolamines. More specifically, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine , Hexadecylamine, heptadecylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine Decylamine, ditetradecylamine, dipentadecylamine, dihexadecylamine, diheptadecylamine, dioctadecylamine, methyl ethyl Alkylamines having an alkyl group having 1 to 30 carbon atoms such as amine, methylpropylamine, methylbutylamine, ethylpropylamine, ethylbutylamine, and propylbutylamine (these alkyl groups may be linear or branched); Alkenyl amines having 2 to 30 carbon atoms such as ethenylamine, propenylamine, butenylamine, octenylamine, and oleylamine (these alkenyl groups may be linear or branched); methanolamine, ethanolamine, propanolamine , Butanolamine, pentanolamine, hexanolamine, heptanolamine, octanolamine, nonanolamine, methanol ethanolamine, methanol propanolamine, methanol butanol amine Alkanolamines having 1 to 30 carbon atoms such as ethanolpropanolamine, ethanolbutanolamine, and propanolbutanolamine (these alkanol groups may be linear or branched); methylenediamine, ethylenediamine, Alkylene diamines having 1-30 carbon atoms such as propylene diamine and butylene diamine; polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine; undecyl diethylamine, undecyl diethanolamine, dodecyl dipropanol Amine, oleyl diethanolamine, oleyl propylene diamine, stearyl tetraethylene pentamine, etc. Examples thereof include compounds having an alkyl group or alkenyl group having 8 to 20 carbon atoms in the amine and heterocyclic compounds such as imidazoline; alkylene oxide adducts of these compounds; and mixtures thereof. Of these amine compounds, primary amines, secondary amines and alkanolamines are preferred.

  Carbon number of the hydrocarbon group which the amine compound which comprises a molybdenum-amine complex has becomes like this. Preferably it is 4 or more, More preferably, it is 4-30, Most preferably, it is 8-18. When the number of carbon atoms of the hydrocarbon group of the amine compound is less than 4, the solubility tends to deteriorate. Moreover, by setting the number of carbon atoms of the amine compound to 30 or less, the molybdenum content in the molybdenum-amine complex can be relatively increased, and the effects of the present invention can be further enhanced with a small amount of compounding.

  The molybdenum-succinimide complex is a complex of a sulfur-free molybdenum compound as exemplified in the description of the molybdenum-amine complex and a succinimide having an alkyl group or alkenyl group having 4 or more carbon atoms. Is mentioned. As the succinimide, a succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms or an alkenyl group in the molecule described in the ashless dispersant, or a carbon number of 4 to 39, preferably carbon number. Examples thereof include succinimide having 8 to 18 alkyl groups or alkenyl groups. If the alkyl group or alkenyl group in the succinimide has less than 4 carbon atoms, the solubility tends to deteriorate. A succinimide having an alkyl group or an alkenyl group having more than 30 carbon atoms and not more than 400 carbon atoms can also be used. By setting the alkyl group or alkenyl group to 30 or less carbon atoms, molybdenum-succinimide is obtained. The molybdenum content in the complex can be relatively increased, and the effects of the present invention can be further enhanced with a small amount of compounding.

  Examples of the molybdenum salt of an organic acid include salts of molybdenum bases such as molybdenum oxide or molybdenum hydroxide, molybdenum carbonate or molybdenum chloride exemplified in the description of the molybdenum-amine complex with an organic acid. It is done. As an organic acid, the phosphorus compound and carboxylic acid which are represented by General formula (3) or (4) are preferable. Here, about the preferable aspect of General formula (3) in the molybdenum salt of the phosphorus compound represented by General formula (3) or (4), (4) shall be the same as that of the case of the phosphorus additive mentioned later. Can do.

  Moreover, as carboxylic acid which comprises the molybdenum salt of carboxylic acid, either a monobasic acid or a polybasic acid may be sufficient.

  As the monobasic acid, a fatty acid having 2 to 30 carbon atoms, preferably 4 to 24 carbon atoms, is used. The fatty acid may be linear or branched, and may be saturated or unsaturated. . Specifically, for example, acetic acid, propionic acid, linear or branched butanoic acid, linear or branched pentanoic acid, linear or branched hexanoic acid, linear or branched heptane Acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched decanoic acid, linear or branched undecanoic acid, linear or branched dodecane Acid, linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched hexadecanoic acid, linear or branched heptadecane Acid, linear or branched octadecanoic acid, linear or branched hydroxyoctadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, linear or branched Henicosanoic acid, linear or branched Saturated fatty acids such as cosanoic acid, linear or branched tricosanoic acid, linear or branched tetracosanoic acid, acrylic acid, linear or branched butenoic acid, linear or branched pentenoic acid, Linear or branched hexenoic acid, linear or branched heptenoic acid, linear or branched octenoic acid, linear or branched nonenoic acid, linear or branched decenoic acid, Linear or branched undecenoic acid, linear or branched dodecenoic acid, linear or branched tridecenoic acid, linear or branched tetradecenoic acid, linear or branched pentadecenoic acid, Linear or branched hexadecenoic acid, linear or branched heptadecenoic acid, linear or branched octadecenoic acid, linear or branched hydroxyoctadecenoic acid, linear or branched nonadecene Acid, linear or branched Unsaturated fatty acids such as cocenoic acid, linear or branched heicosenoic acid, linear or branched docosenoic acid, linear or branched tricosenoic acid, linear or branched tetracosenoic acid, and the like And the like.

  Moreover, as a monobasic acid, in addition to the above fatty acid, a monocyclic or polycyclic carboxylic acid (which may have a hydroxyl group) may be used, and the carbon number thereof is preferably 4 to 30, and more preferably. Is 7-30. The monocyclic or polycyclic carboxylic acid is an aromatic carboxylic acid having 0 to 3, preferably 1 to 2 linear or branched alkyl groups having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms. Or cycloalkyl carboxylic acid etc. are mentioned, More specifically, (alkyl) benzene carboxylic acid, (alkyl) naphthalene carboxylic acid, (alkyl) cycloalkyl carboxylic acid, etc. can be illustrated. Preferable examples of the monocyclic or polycyclic carboxylic acid include benzoic acid, salicylic acid, alkylbenzoic acid, alkylsalicylic acid, and cyclohexanecarboxylic acid.

  Examples of polybasic acids include dibasic acids, tribasic acids, and tetrabasic acids. The polybasic acid may be a chain polybasic acid or a cyclic polybasic acid. Further, in the case of a chain polybasic acid, it may be either linear or branched, and may be either saturated or unsaturated. As the chain polybasic acid, a chain dibasic acid having 2 to 16 carbon atoms is preferable. Specifically, for example, ethanedioic acid, propanedioic acid, linear or branched butanedioic acid, linear Or branched pentanedioic acid, linear or branched hexanedioic acid, linear or branched heptanedioic acid, linear or branched octanedioic acid, linear or branched nonane diacid Acid, linear or branched decanedioic acid, linear or branched undecanedioic acid, linear or branched dodecanedioic acid, linear or branched tridecanedioic acid, linear or Branched tetradecanedioic acid, linear or branched heptadecanedioic acid, linear or branched hexadecanedioic acid, linear or branched hexenedioic acid, linear or branched heptenedioic acid Linear or branched octene diacid, linear or branched nonene diacid, linear or branched Branched decenedioic acid, linear or branched undecenedioic acid, linear or branched dodecenedioic acid, linear or branched tridecenedioic acid, linear or branched tetradecenedioic acid And linear or branched heptadecene diacid, linear or branched hexadecene diacid, alkenyl succinic acid, and mixtures thereof. As the cyclic polybasic acid, 1,2-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid alicyclic dicarboxylic acid, phthalic acid or other aromatic dicarboxylic acid, trimellitic acid or other aromatic Examples thereof include aromatic tetracarboxylic acids such as tricarboxylic acid and pyromellitic acid.

  Examples of the molybdenum salt of the alcohol include a salt of a molybdenum compound not containing sulfur as exemplified in the description of the molybdenum-amine complex with an alcohol. The alcohol may be a monohydric alcohol, a polyhydric alcohol, Any of a partial ester or partial ester compound of a monohydric alcohol, a nitrogen compound having a hydroxyl group (alkanolamine, etc.), etc. may be used. Molybdic acid is a strong acid and forms an ester by reaction with alcohol. The ester of molybdic acid and alcohol is also included in the molybdenum salt of alcohol in the present invention.

  As the monohydric alcohol, those having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms are usually used. Such alcohols may be linear or branched, and saturated. Or may be unsaturated. Specific examples of the alcohol having 1 to 24 carbon atoms include methanol, ethanol, linear or branched propanol, linear or branched butanol, linear or branched pentanol, and linear Linear or branched hexanol, linear or branched heptanol, linear or branched octanol, linear or branched nonanol, linear or branched decanol, linear or branched Undecanol, linear or branched dodecanol, linear or branched tridecanol, linear or branched tetradecanol, linear or branched pentadecanol, linear or branched hexadecane Decanol, linear or branched heptadecanol, linear or branched octadecanol, linear or branched nonadecanol, linear or branched icosa Lumpur, linear or branched Hen'ikosanoru, linear or branched Torikosanoru, such as linear or branched tetracosanol, and mixtures thereof.

  Moreover, as a polyhydric alcohol, the thing of 2-10 valence is preferable, Preferably it is 2-6 valence. Specific examples of the 2 to 10 polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, polyethylene glycol (3 to 15 mer of ethylene glycol), propylene glycol, dipropylene glycol, and polypropylene glycol (3 to 15 of propylene glycol). Monomer), 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3 -Dihydric alcohols such as propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentylglycol; glycerin, polyglycerin (glycerin 2- Octamers such as diglycerin, triglyceride Phosphorus, tetraglycerin, etc.), trimethylolalkanes (trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) and their 2- to 8-mer, pentaerythritol and their 2- to 4-mer, 1,2,4- Butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol, etc. Polyhydric alcohols; sugars such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, and mixtures thereof That.

  Examples of the partial ester of the polyhydric alcohol include compounds in which a part of the hydroxyl group of the polyhydric alcohol exemplified in the description of the polyhydric alcohol has been hydrocarbyl esterified, among which glycerin monooleate and glycerin dioleate. Sorbitan monooleate, sorbitandiolate, pentaerythritol monooleate, polyethylene glycol monooleate, polyglycerin monooleate and the like are preferable.

  Moreover, as the partial ether of the polyhydric alcohol, an ether bond is formed by condensation of polyhydric alcohols, a compound in which a part of the hydroxyl groups of the polyhydric alcohol exemplified in the description of the polyhydric alcohol is hydrocarbyl etherified. Compounds (such as sorbitan condensate) and the like, among which 3-octadecyloxy-1,2-propanediol, 3-octadecenyloxy-1,2-propanediol, polyethylene glycol alkyl ether and the like are preferable.

  Examples of the nitrogen compound having a hydroxyl group include alkanolamines exemplified in the description of the molybdenum-amine complex, and alkanolamides (diethanolamide, etc.) in which the amino group of the alkanol is amidated. Among them, stearyldiethanolamine Polyethylene glycol stearylamine, polyethylene glycol dioleylamine, hydroxyethyl laurylamine, oleic acid diethanolamide and the like are preferable.

  In the lubricating oil composition of the present invention, the content of the organic molybdenum compound not containing sulfur as a constituent element is preferably 10 ppm by mass or more, more preferably 30 ppm by mass or more, in terms of molybdenum element, based on the total amount of the composition. More preferably, it is 100 mass ppm or more, preferably 1000 mass ppm or less, more preferably 600 mass ppm or less, and still more preferably 400 mass ppm or less. When the content of the organomolybdenum compound is less than 10 ppm by mass in terms of molybdenum element, the combination of the molybdenum compound and the lubricating base oil provides antioxidant properties, base number maintenance, high temperature cleanliness, and resistance to NOx. The improvement effect tends to be insufficient, and even if it exceeds 1000 ppm by mass, the above improvement effect commensurate with the increase in content tends not to be obtained.

  The lubricating oil composition of the present invention contains an aromatic compound having a nitrogen atom, an oxygen atom or a sulfur atom in addition to the organic molybdenum compound. As such an aromatic compound, an aromatic compound represented by the following general formula (1) is preferably used.

[Wherein, A represents an aromatic ring, X represents a monovalent functional group having at least one nitrogen atom, oxygen atom or sulfur atom, and R represents an organic group having 1 to 40 carbon atoms (provided that tert- A is an integer of 1 or more, b is an integer of 1 or more when A is an aromatic carbocyclic ring, and b is an integer of 0 or 1 when A is an aromatic heterocyclic ring. Indicates. ]
The aromatic ring represented by A in the general formula (1) is not particularly limited as long as it has aromaticity, and may be either an aromatic carbocyclic ring or an aromatic heterocyclic ring.

  The aromatic ring represented by A may be either an aromatic carbocyclic ring or an aromatic heterocyclic ring. Specifically, a benzene ring, naphthalene ring, fluorene ring, anthracene ring, phenanthrene ring, fluoranthene ring, pyrene ring Perylene ring, pyrrole ring, imidazole ring, pyrazole ring, pyridine ring, pyrazine ring, pyrimidine ring, indole ring, quinoline ring, isoquinoline ring, quinolidine ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, triazine ring , Furan ring, thiophene ring, imidazoline ring, pyrrolidine ring, piperidine ring, piperazine ring, pyridazine ring, purine ring, quinazoline ring, acridine ring, carbazole ring, phenothiazine ring, phenoxazine ring, phenanthroline ring, benzotriazole ring, indazole ring Ben Imidazole ring, a porphyrin ring, phthalocyanine ring, and the like derivatives thereof. Among these, examples of the aromatic ring represented by A include a benzene ring, naphthalene ring, fluorene ring, anthracene ring, phenanthrene ring, quinoline ring, biquinoline ring, pyridine ring, bipyridine ring, terpyridine ring, phenanthroline ring, pyrrole ring and Indole rings are preferred.

Examples of the organic group having 1 to 40 carbon atoms represented by R include an alkyl group having 1 to 40 carbon atoms (excluding a tert-butyl group), an SH group at the side chain or the terminal of these alkyl groups, A group having an OH group or NH ₂ group bonded thereto is preferred. Specific examples of the alkyl group having 1 to 40 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a linear or branched butyl group, and a linear or branched pentyl. Group, linear or branched hexyl group, linear or branched heptyl group, linear or branched octyl group, linear or branched nonyl group, linear or Branched decyl group, linear or branched undecyl group, linear or branched dodecyl group, linear or branched tridecyl group, linear or branched tetradecyl group , Linear or branched pentadecyl group, linear or branched hexadecyl group, linear or branched heptadecyl group, linear or branched octadecyl group, linear or branched Branched nonadecyl group, linear or branched icosyl group, straight Linear or branched docosyl group, linear or branched tricosyl group, linear or branched tetracosyl group, linear or branched Pentacosyl group, linear or branched hexacosyl group, linear or branched heptacosyl group, linear or branched octacosyl group, linear or branched nonacosyl group, linear Or a branched triacontyl group, a linear or branched hentriacontyl group, a linear or branched dotriacontyl group, a linear or branched tritriacontyl group, a linear or branched group Branched tetratriacontyl group, linear or branched pentatriacontyl group, linear or branched hexatriacontyl group, linear or branched heptatriacontyl group , Linear or minute Jo oct triacontyl group, straight or branched nonadecyl triacontyl group, straight or branched tetracontyl group (including all isomers). Among these, the organic group represented by R is preferably a linear or branched alkyl group having preferably 4 to 30, more preferably 6 to 24, and still more preferably 8 to 18 carbon atoms.

X in the general formula (1) represents a monovalent functional group having at least one sulfur atom, oxygen atom or nitrogen atom. Examples of the functional group represented by X include mercapto group (—SH), hydroxyl group (—OH), amino group (—NH ₂ ), imino group, azo group, diazo group, oxyimino group, oxyamino group, hydrazo group, hydrazide. Group, diazoamino group, carbamoyl group, carbonyl group, thiocarbonyl group, isocyanic group and the like. Among them, mercapto group, amino group and oxy group are preferable. From the viewpoint of reducing sulfur in the lubricating oil composition, oxy group or amino group is preferable. Groups are more preferred.

  A in general formula (1) is an integer greater than or equal to 1, Preferably it is an integer of 1-3. When a is 2 or more, a R may be the same or different. It is preferable that a is 1 or 2 from the point which is excellent in the combined use effect with an organic molybdenum compound.

  When A is an aromatic carbocycle, b is an integer of 1 or more, and when A is an aromatic heterocycle, b is 0 or an integer of 1 or more. When b is 2 or more, b pieces of X may be the same or different. It is preferable that b is 1 or 2 from the point which is excellent in the combined effect with an organic molybdenum compound.

  The molecular weight of the aromatic compound represented by the general formula (1) is not particularly limited, but is preferably 150 to 1000, and more preferably 250 to 500. When the molecular weight of the aromatic compound is less than the lower limit, the oxidation stability at high temperatures tends to be inferior. On the other hand, when the upper limit is exceeded, the effect on the blending amount tends to be small.

  Of the aromatic compounds represented by the general formula (1), preferred examples of the aromatic carbocyclic compound include benzoyl group, phenylacetyl group, phenacyl group, benzyloxy group, benzoyloxy group, p -Aromatic carbon having toluoyl group, anilino group, phenylimino group, phenylazo group, benzamide group, benzenesulfinyl group, benzenesulfonyl group, benzenesulfonamide group, sulfanyl group, naphthyloxy group, naphthoyl group, naphthoyloxy group, etc. Examples thereof include compounds derived from ring compounds and alkylated products thereof. More specifically, triazine, salicylaldehyde, 2-oxyazo compound, 2-hydroxynaphthalaldehyde-1,2-hydroxyhaphthalide-3, C-methylbenzoylacetone, cis or trans-α-benzoin oxime, salicylaldoxime Bissalicylaldoxime, bissalicylaldehyde ethylenediimine, bisbenzoylacetonate, eriochrome black T, alizarin, o-aminophenol, isophthalsan dihydrazide and its polymer with chloride in isophthalic acid, glyoxal bishydroxyanil and its Examples thereof include compounds derived from thio derivatives and alkylated products thereof.

  Further, among the aromatic compounds represented by the general formula (1), preferred examples of the compound having an aromatic heterocycle include, specifically, indole, indazole, benzimidazole, methylbenzotriazole, quinoline, isoquinoline, Quinazoline, acridine, carbazole, phenothiazine, phenoxazine, oxine, quinaldic acid, picolinic acid, 2,2'-bipyridine, 3,3'-dimethyl-2,2'-bipyridine, 6,6'-dimethyl-2,2 '-Bipyridine, 1,10-phenanthroline, terpyridine, biquinoline, phthalocyanine, 8-oxyquinoline, 8-mercaptoquinoline, 2-methyloxine, 8,8'-dioxy-5,5'-biquinolyl, and alkylated products thereof And the like.

  Among these, as the aromatic compound represented by the general formula (1), alkylphenol, alkylcatechol, alkylaniline, alkylsalicylaldehyde, alkylnaphthol, alkylnaphthylaldehyde, alkylnaphthylamine, alkylpyridine, alkylbipyridine, alkylindole, Alkyloxyquinolinoline, alkylmercaptoquinolinoline, alkylquinazoline, alkylacridine, alkylcarbazole, and alkylphenoxazine are preferable. Moreover, as for carbon number of the alkyl group which these aromatic compounds have, 1-40 are preferable.

  In the lubricating oil composition of the present invention, the content of the aromatic compound represented by the general formula (1) is preferably 0.01% by mass or more, more preferably 0.1% by mass, based on the total amount of the composition. More preferably, it is 0.5% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass or less. When the content of the compound represented by the general formula (1) is less than the lower limit, the effect of improving the anti-oxidation property, the base number maintenance property, the high-temperature cleanability and the resistance to NOx by the combined use with the organic molybdenum compound is insufficient. In addition, even if the upper limit is exceeded, the above improvement effect commensurate with the increase in content tends not to be obtained.

  The lubricating oil composition of the present invention may be composed only of the above lubricating base oil, an organic molybdenum compound, and the aromatic compound represented by the general formula (1). An additive can be further contained. For example, when the lubricating oil composition of the present invention is used as a lubricating oil for an internal combustion engine, it is preferable to further contain the following additives.

  The lubricating oil composition of the present invention comprises a phosphorus compound represented by the general formula (2), a phosphorus compound represented by the general formula (3), and metal salts thereof (excluding molybdenum salts) or amine salts. It is preferable to further contain at least one selected phosphorus additive (phosphorus-containing antiwear agent).

[Wherein, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, R ² and R ³ may be the same or different, and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; ¹ , X ² and X ³ may be the same or different and each represents an oxygen atom or a sulfur atom, n represents 0 or 1, and when n is 0, at least one of X ² or X ³ is oxygen An atom, and when n is 1, at least one of X ¹ , X ² or X ³ is an oxygen atom. ]

[Wherein, R ⁴ represents a hydrocarbon group having 1 to 30 carbon atoms, R ⁵ and R ⁶ may be the same or different, and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; ⁴ , X ⁵ , X ⁶ and X ⁷ may be the same or different and each represents an oxygen atom or a sulfur atom, n represents 0 or 1, and when n is 0, X ⁵ , X ⁶ or X ⁷ At least two of them are oxygen atoms, and when n is 1, at least three of X ⁴ , X ⁵ , X ⁶ or X ⁷ are oxygen atoms. ]
Specific examples of the hydrocarbon group having 1 to 30 carbon atoms represented by R ^{1 to} R ⁶ in the general formulas (2) and (3) include an alkyl group, a cycloalkyl group, an alkenyl group, and alkyl substitution. Mention may be made of cycloalkyl groups, aryl groups, alkyl-substituted aryl groups, and arylalkyl groups.

  Examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and the like. Group, hexadecyl group, heptadecyl group, octadecyl group and other alkyl groups (these alkyl groups may be linear or branched).

  As said cycloalkyl group, C5-C7 cycloalkyl groups, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, can be mentioned, for example. Examples of the alkylcycloalkyl group include a methylcyclopentyl group, a dimethylcyclopentyl group, a methylethylcyclopentyl group, a diethylcyclopentyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a methylethylcyclohexyl group, a diethylcyclohexyl group, a methylcycloheptyl group, Examples thereof include an alkylcycloalkyl group having 6 to 11 carbon atoms such as a dimethylcycloheptyl group, a methylethylcycloheptyl group, and a diethylcycloheptyl group (the substitution position of the alkyl group with the cycloalkyl group is also arbitrary).

  Examples of the alkenyl group include butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, An alkenyl group such as an octadecenyl group (these alkenyl groups may be linear or branched, and the position of the double bond is also optional).

  As said aryl group, aryl groups, such as a phenyl group and a naphthyl group, can be mentioned, for example. Examples of the alkylaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, and decylphenyl. A C7-C18 alkylaryl group such as a group, undecylphenyl group, dodecylphenyl group, etc. (the alkyl group may be linear or branched, and the substitution position on the aryl group is arbitrary) Can do.

  Examples of the arylalkyl group include arylalkyl groups having 7 to 12 carbon atoms such as benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, phenylpentyl group, and phenylhexyl group. It may be branched).

^R 1 above hydrocarbon group having 1 to 30 carbon atoms represented by the to R ^6, preferably an alkyl group or an aryl group having 6 to 24 carbon atoms having 1 to 30 carbon atoms, more preferably 3 carbon atoms -18, more preferably an alkyl group having 4 to 12 carbon atoms.

  Examples of the phosphorus compound represented by the general formula (2) include phosphorous acid monoester, monothiophosphorous acid monoester, (hydrocarbyl) phosphonous acid having one hydrocarbon group having 1 to 30 carbon atoms, (Hydrocarbyl) monothiophosphonous acid; phosphorous diester having two hydrocarbon groups having 1 to 30 carbon atoms, monothiophosphorous diester, (hydrocarbyl) phosphonous monoester, (hydrocarbyl) monothiophosphonous mono Esters; phosphorous acid triesters having three hydrocarbon groups having 1 to 30 carbon atoms, monothiophosphorous acid triesters, (hydrocarbyl) phosphonic acid diesters, (hydrocarbyl) monothiophosphonic acid diesters; and mixtures thereof Etc.

In the present invention, the compound represented by the general formula (2) is preferably a compound in which all of X ^{1 to} X ³ are oxygen atoms, that is, a compound represented by the following general formula (4).

[Wherein, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, R ² and R ³ may be the same or different, and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; Represents 0 or 1. ]
Examples of the phosphorus compound represented by the general formula (3) include phosphoric acid monoester, monothiophosphoric acid monoester, (hydrocarbyl) phosphonic acid, and (hydrocarbyl) mono having one hydrocarbon group having 1 to 30 carbon atoms. Thiophosphonic acid; phosphoric acid diester having two hydrocarbon groups having 1 to 30 carbon atoms, monothiophosphoric acid diester, (hydrocarbyl) phosphonic acid monoester, (hydrocarbyl) monothiophosphonic acid monoester; And phosphoric acid triesters having three hydrocarbon groups, monothiophosphoric acid triesters, (hydrocarbyl) phosphonic acid diesters, (hydrocarbyl) monothiophosphonic acid diesters, and mixtures thereof.

In the present invention, the compound represented by the general formula (3) is preferably a compound in which all of X ^{4 to} X ⁷ are oxygen atoms, that is, a compound represented by the following general formula (5).

[Wherein, R ⁴ , R ⁵ and R ⁶ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and n represents 0 or 1. ]
In addition, the metal salt or amine salt of the phosphorus compound represented by the general formula (2) or (3) is obtained by adding a metal oxide or metal hydroxide to the phosphorus compound represented by the general formula (2) or (3). A metal base such as a metal carbonate, metal chloride, ammonia, a nitrogen compound such as an amine compound having only a hydrocarbon group having 1 to 30 carbon atoms or a hydroxyl group-containing hydrocarbon group in the molecule, and the like. It can be obtained by neutralizing part or all of the acidic hydrogen.

  Specific examples of the metal in the metal base include alkali metals such as lithium, sodium, potassium and cesium, alkaline earth metals such as calcium, magnesium and barium, zinc, copper, iron, lead, nickel, silver and manganese. And heavy metals (excluding molybdenum). Among these, alkaline earth metals such as calcium and magnesium and zinc are preferable, and zinc is particularly preferable.

  The structure of the metal salt of the phosphorus compound differs depending on the valence of the metal or the number of OH groups or SH groups of the phosphorus compound, and therefore the structure of the metal salt of the phosphorus compound is not limited at all. For example, when 1 mol of zinc oxide and 2 mol of phosphoric diester (compound with one OH group) are reacted, it is considered that a compound having a structure represented by the following formula (6) is obtained as a main component. Is also considered to exist.

[In formula, R shows a hydrogen atom or a C1-C30 hydrocarbon group each independently. ]
Further, for example, when 1 mol of zinc oxide and 1 mol of phosphoric acid monoester (a compound having two OH groups) are reacted, it is considered that a compound having a structure represented by the following formula (7) is obtained as a main component. Polymerized molecules are also thought to exist.

[In formula, R shows a hydrogen atom or a C1-C30 hydrocarbon group. ]
Specific examples of the nitrogen compound include monoamines, diamines, polyamines, and alkanolamines exemplified in the description of the molybdenum-amine complex. In addition, heterocyclic compounds such as N-hydroxyethyloleylimidazoline, amine alkylene oxide adducts to amine compounds, and the like can also be used.

  Among these nitrogen compounds, aliphatic amines having an alkyl group or alkenyl group having 10 to 20 carbon atoms such as decylamine, dodecylamine, tridecylamine, heptadecylamine, octadecylamine, oleylamine and stearylamine A branched example) may be mentioned as a preferred example.

  In the present invention, the phosphorus additives may be used alone or in combination of two or more.

  As the phosphorus-based additive according to the present invention, a phosphorus compound represented by the above general formula (3) or (4) or a metal salt thereof (excluding molybdenum salt) is preferable. Phosphorous acid diester having two alkyl groups or aryl groups and zinc or calcium salt, phosphorous acid having 3 to 18 carbon atoms or preferably 3 to 6 carbon atoms Triester, salt of phosphoric acid monoester having one alkyl group or aryl group having 3 to 18 carbon atoms and zinc or calcium, diester of phosphoric acid having two alkyl groups or aryl group having 3 to 18 carbon atoms Salt of zinc and calcium, or phosphoric acid triester having 3 alkyl groups or aryl groups having 3 to 18 carbon atoms, preferably 3 alkyl groups having 6 to 12 carbon atoms , A salt of a phosphonous acid having one alkyl group or aryl group having 1 to 18 carbon atoms (hydrocarbyl) and zinc or calcium, a phosphonone having two alkyl groups or aryl groups having 1 to 18 carbon atoms (hydrocarbyl) Salt of acid monoester and zinc or calcium, 3 alkyl group having 1 to 18 carbon atoms or aryl group (hydrocarbyl) phosphonous acid diester, 1 alkyl group having 1 to 18 carbon atoms or aryl group ( (Hydrocarbyl) salt of phosphonic acid and zinc or calcium, salt of alkyl group or aryl group having 1 to 18 carbon atoms (hydrocarbyl) phosphonic acid monoester and zinc or calcium, alkyl group of 1 to 18 carbon atoms Alternatively, (hydrocarbyl) phosphonic acid diester having three aryl groups is preferred.

  The above (hydrocarbyl) (sub) phosphonic acid, metal salt thereof, (hydrocarbyl) (sub) phosphonic acid monoester, metal salt thereof, and (hydrocarbyl) (sub) phosphonic acid diester have oil solubility and extreme pressure. Therefore, the total carbon number of the hydrocarbon group is preferably 12 to 30, more preferably 14 to 24, and still more preferably 16 to 20.

  In the lubricating oil composition of the present invention, the phosphorus additive content is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and more preferably 0.01% by mass or more, in terms of phosphorus element, based on the total amount of the composition. Preferably it is 0.02 mass% or more, preferably 0.5 mass% or less, more preferably 0.2 mass% or less, still more preferably 0.1 mass% or less, particularly preferably 0.08. It is below mass%. When the content of the phosphorus-based additive is less than 0.005% by mass in terms of phosphorus element, the wear prevention property is insufficient, and a long drain tends to be hardly achieved. On the other hand, even if the content of the phosphorus additive exceeds 0.5% by mass in terms of phosphorus element, the above improvement effect commensurate with the increase in content tends not to be obtained, and the lubricating oil composition of the present invention When using as a lubricating oil for internal combustion engines, there is a concern about the adverse effect of phosphorus on the exhaust gas aftertreatment device. From the point that the influence on the exhaust gas aftertreatment device can be remarkably reduced, the content of the phosphorus-based additive is 0.08% by mass or less, particularly 0.05% by mass or less in terms of phosphorus element. Is preferred.

  Of the phosphorus-based additives in the present invention, the sulfur-containing compound can also be contained within the range of the phosphorus element amount, but the content of the compound is preferably in terms of sulfur element, preferably It is 0.1 mass% or less, More preferably, it is 0.08 mass% or less. The lubricating oil composition of the present invention does not contain a sulfur-containing compound as a phosphorus additive, that is, the phosphorus compound represented by the general formula (4) or (5) or a metal thereof Most preferably, it is composed only of a salt (excluding molybdenum salt) or an amine salt.

  In addition, the lubricating oil composition of the present invention preferably further contains a metallic detergent in order to further improve its acid neutralization characteristics, high temperature cleanability and wear resistance.

  Examples of the metal detergent include alkali metal sulfonate or alkaline earth metal sulfonate, alkali metal phenate or alkaline earth metal phenate, alkali metal salicylate or alkaline earth metal salicylate, alkali metal phosphonate or alkaline earth metal phosphonate, or These mixtures etc. are mentioned.

  More specifically, the alkali metal or alkaline earth metal sulfonate is an alkali metal salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a molecular weight of 100 to 1500, preferably 200 to 700, for example. Alternatively, alkaline earth metal salts, particularly magnesium salts and / or calcium salts are preferably used. Specific examples of the alkyl aromatic sulfonic acids include so-called petroleum sulfonic acids and synthetic sulfonic acids.

  As the petroleum sulfonic acid, those obtained by sulfonating an alkyl aromatic compound of a lubricating oil fraction of mineral oil or so-called mahoganic acid which is produced as a by-product when white oil is produced is used. As the synthetic sulfonic acid, for example, an alkylbenzene having a linear or branched alkyl group obtained as a by-product from an alkylbenzene production plant that is a raw material for detergents or by alkylating polyolefin with benzene is used as a raw material. , Sulfonated ones thereof, sulfonated ones of dinonylnaphthalene, and the like are used. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, but usually fuming sulfuric acid or sulfuric acid is used.

  More specifically, the alkali metal or alkaline earth metal phenate is an alkylphenol having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms, and the alkylphenol and element. Alkyl metal salts or alkaline earth metal salts, especially magnesium salts and / or calcium salts of Mannich reaction products of alkylphenols obtained by reacting sulfur with alkylphenols obtained by reacting this alkylphenol with formaldehyde are preferably used. .

  More specifically, the alkali metal or alkaline earth metal salicylate is an alkali metal salt of an alkyl salicylic acid having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms. Alternatively, alkaline earth metal salts, particularly magnesium salts and / or calcium salts are preferably used.

  Alkali metal or alkaline earth metal sulfonate, alkali metal or alkaline earth metal phenate and alkali metal or alkaline earth metal salicylate include alkyl aromatic sulfonic acid, alkylphenol, alkylphenol sulfide, Mannich reaction product of alkylphenol, alkyl Salicylic acid or the like is directly reacted with a metal base such as an oxide or hydroxide of an alkali metal or alkaline earth metal, or once converted to an alkali metal salt such as a sodium salt or potassium salt and then replaced with an alkaline earth metal salt In addition to the neutral salt (normal salt) obtained by, etc., these neutral salt (normal salt) and excess alkali metal or alkaline earth metal salt or alkali metal or alkaline earth metal base (alkali metal or Alkali earth metal hydroxides and acids Product) heated in the presence of water, or neutral salt (normal salt) of alkali metal or alkaline earth metal in the presence of carbon dioxide, boric acid or borate. An overbased salt (superbasic salt) obtained by reacting with a base such as a product is also included. These reactions are usually carried out in a solvent (an aliphatic hydrocarbon solvent such as hexane, an aromatic hydrocarbon solvent such as xylene, a light lubricating base oil).

  In addition, metal detergents are usually marketed in a state diluted with a light lubricating base oil or the like, and are available, but generally the metal content is 1.0 to 20% by mass. It is desirable to use 2.0 to 16% by mass. The total base number of the metal detergent is usually 0 to 500 mgKOH / g, preferably 20 to 450 mgKOH / g. The total base number referred to here is JIS K2501 “Petroleum products and lubricating oils—Test method for neutralization number”. It means the total base number measured by the perchloric acid method based on

  In the present invention, one selected from sulfonates, phenates, salicylates and the like of alkali metals or alkaline earth metals can be used alone or in combination of two or more. In the present invention, an alkali metal or alkaline earth metal salicylate is particularly preferable as the metal detergent because it has a large friction reducing effect and / or wear prevention effect due to low ashing and is excellent in long drain properties. Moreover, it is especially preferable to use an alkali metal or alkaline earth metal sulfonate from the point which can suppress a viscosity increase more.

  The metal ratio of the metal-based detergent is not particularly limited, and usually 20 or less can be used. However, a metal having a metal ratio of 1 to 10 is preferable because it can further improve the friction reduction effect and the long drain property. It is preferable that it consists of 1 type (s) or 2 or more types chosen from a type | system | group detergent. The metal ratio here is represented by the valence of the metal element in the metal detergent × the metal element content (mol%) / the soap group content (mol%). The metal elements are calcium and magnesium. Etc., a soap group means a sulfonic acid group, a salicylic acid group, and the like.

  As the metal detergent, alkali metal or alkaline earth metal salicylate is particularly preferable in that it has a large friction reducing effect due to low ashing and is excellent in long drain properties.

  The upper limit of the content of the metallic detergent in the lubricating oil composition of the present invention is not particularly limited and is usually 0.5% by mass or less based on the total amount of the composition, but the composition based on the total amount of the composition It is preferable to adjust together with other additives so that the sulfated ash content of the product is 1.0% by mass or less. From such a viewpoint, the content of the metal detergent is preferably 0.3% by mass or less, more preferably 0.23% by mass or less, in terms of metal element, based on the total amount of the composition. Further, the content of the metal detergent is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and further preferably 0.15% by mass or more. When the content of the metal detergent is less than 0.01% by mass, it is difficult to obtain long drain performance such as high temperature cleanability, oxidation stability, and base number maintenance, which is not preferable.

  Moreover, 0.1-500 are preferable and, as for mass ratio (M / Mo) of the metal (M) contained in a metal type cleaning agent, and molybdenum (Mo) contained in an organic molybdenum compound, 2-100 are more preferable. 3 to 60 are more preferable, 5 to 50 are more preferable, and 10 to 40 are particularly preferable.

  The lubricating oil composition of the present invention preferably further contains an ashless dispersant.

  As the ashless dispersant, any ashless dispersant used in lubricating oils can be used. For example, at least one linear or branched alkyl group or alkenyl group having 40 to 400 carbon atoms is included in the molecule. Examples thereof include nitrogen-containing compounds or derivatives thereof, or modified products of alkenyl succinimide. One type or two or more types arbitrarily selected from these can be blended.

  The alkyl group or alkenyl group has 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms. When the carbon number of the alkyl group or alkenyl group is less than 40, the solubility of the compound in the lubricating base oil decreases. On the other hand, when the carbon number of the alkyl group or alkenyl group exceeds 400, the low temperature of the lubricating oil composition Since fluidity | liquidity deteriorates, it is not preferable respectively. This alkyl group or alkenyl group may be linear or branched, but specifically, preferred are derived from olefin oligomers such as propylene, 1-butene and isobutylene, and co-oligomers of ethylene and propylene. And a branched alkyl group and a branched alkenyl group.

Specific examples of the ashless dispersant include the following compounds. One or more compounds selected from these can be used.
(I) Succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof (II) At least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule A benzylamine having a derivative thereof (III) A polyamine having at least one alkyl or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof.

  More specifically, examples of the (I) succinimide include compounds represented by the following general formula (8) or (9).

[Wherein, R ⁷ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and m represents an integer of 1 to 5, preferably 2 to 4. ]

[Wherein R ⁸ and R ⁹ each independently represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, more preferably a polybutenyl group, and m is 0 to 4, preferably 1 to 1. An integer of 3 is shown. ]
The succinimide is represented by the formula (8) in which succinic anhydride is added to one end of the polyamine, and the formula (9) in which so-called monotype succinimide is added to both ends of the polyamine. The so-called bis-type succinimide represented by the formula (1) is included, but the lubricating oil composition of the present invention may contain only one of them or a mixture thereof.

  The method for producing the succinimide is not particularly limited. For example, an alkyl or alkenyl succinic acid obtained by reacting a compound having an alkyl group or alkenyl group having 40 to 400 carbon atoms with maleic anhydride at 100 to 200 ° C. is a polyamine. It can obtain by making it react. Specific examples of the polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

  More specifically, examples of (II) benzylamine include compounds represented by the following general formula (9).

[Wherein, R ¹⁰ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and p represents an integer of 1 to 5, preferably 2 to 4. ]
Although the manufacturing method of the said benzylamine is not limited at all, For example, after making polyolefin, such as a propylene oligomer, polybutene, and an ethylene-alpha-olefin copolymer, react with phenol to make alkylphenol, this is made into formaldehyde and It can be obtained by reacting polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine by Mannich reaction.

More specifically, examples of the (III) polyamine include compounds represented by the following general formula (11).
R ¹¹ —NH— (CH ₂ CH ₂ NH) _q —H (11)
[Wherein, R ¹¹ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and q represents an integer of 1 to 5, preferably 2 to 4. ]
The method for producing the polyamine is not limited in any way. For example, after chlorinating a polyolefin such as propylene oligomer, polybutene, and ethylene-α-olefin copolymer, ammonia, ethylenediamine, diethylenetriamine, and triethylene are added thereto. It can be obtained by reacting polyamines such as tetramine, tetraethylenepentamine, and pentaethylenehexamine.

  Moreover, as a derivative of the nitrogen-containing compound mentioned as an example of the ashless dispersant, specifically, for example, the above-mentioned nitrogen-containing compound is a monocarboxylic acid having 1 to 30 carbon atoms (fatty acid, etc.), oxalic acid, phthalic acid, So-called acid modification in which a part or all of the remaining amino group and / or imino group is neutralized or amidated by the action of a polycarboxylic acid having 2 to 30 carbon atoms such as trimellitic acid or pyromellitic acid Compound: A so-called boron-modified compound obtained by allowing boric acid to act on the aforementioned nitrogen-containing compound to neutralize or amidate part or all of the remaining amino group and / or imino group; And a modified compound obtained by combining two or more kinds of modifications selected from acid modification, boron modification, and sulfur modification with the above-mentioned nitrogen-containing compound. Among these derivatives, boron-modified compounds of alkenyl succinimide are excellent in heat resistance and antioxidant properties, and are also effective in the lubricating oil composition of the present invention to further enhance base number maintenance and high temperature cleanability.

  When the ashless dispersant is contained in the lubricating oil composition of the present invention, the content is usually 0.01 to 20% by mass, preferably 0.1 to 10% by mass, based on the total amount of the lubricating oil composition. is there. When the content of the ashless dispersant is less than 0.01% by mass, the effect of maintaining the base number at high temperatures is small. On the other hand, when the content exceeds 20% by mass, the low-temperature fluidity of the lubricating oil composition is greatly increased. Since it deteriorates, it is not preferable respectively.

  Moreover, it is preferable that the lubricating oil composition of the present invention further contains a chain termination type antioxidant. Thereby, since the antioxidant property of a lubricating oil composition is improved more, the base number maintenance property and high temperature detergency in this invention can be improved more.

  Any chain-stopping antioxidant can be used as long as it is generally used in lubricating oils such as phenol-based antioxidants, amine-based antioxidants, and metal-based antioxidants.

  Examples of phenolic antioxidants include 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert-butylphenol), 4,4 ′. -Bis (2-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-methyl-6) -Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl) 6-cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2, 6-di-tert-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4 (N, N′-dimethylaminomethylphenol), 4,4′-thiobis (2-methyl-6) -Tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 2,2'-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4- Hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide 2,2′-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tridecyl-3- (3,5-di-tert-butyl-4-hydroxy Phenyl) propionate, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3-methyl-5-tert-butyl-4-hydroxyphenyl substituted fatty acid esters and the like are preferable examples. Can do. These may be used individually by 1 type, or may mix and use 2 or more types.

  Examples of amine-based antioxidants include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, and dialkyldiphenylamine. These may be used individually by 1 type, or may mix and use 2 or more types.

  Further, the phenolic antioxidant and the amine antioxidant may be used in combination.

  When the chain-stopping antioxidant is contained in the lubricating oil composition of the present invention, the content is usually 5.0% by mass or less, preferably 3.0% by mass or less, based on the total amount of the lubricating oil composition. Yes, more preferably 2.5% by mass or less. When the content exceeds 5.0% by mass, it is not preferable because sufficient antioxidant properties corresponding to the content cannot be obtained. On the other hand, the content is preferably 0.1% by mass or more, preferably 1% by mass, based on the total amount of the lubricating oil composition, in order to further improve the base number maintenance property and high temperature cleanability in the process of lubricating oil deterioration. That's it.

  The phosphorus-based additives mentioned above include compounds that do not dissolve in the lubricating base oil or compounds that have low solubility (for example, zinc dialkyl phosphate that is solid at room temperature). When using such compounds, nitrogen-containing compounds (for example, amine compounds and chain terminations as ashless dispersants) can be used to improve the solubility of phosphorus additives in lubricating base oils and shorten the production time of lubricating oil compositions. Lubricating oil composition using dissolved product or reaction product obtained by mixing amine-type antioxidant as mixture type antioxidant or mixture thereof) and phosphorus-based additive and dissolving or reacting them as oil-soluble additive It is particularly preferable to blend in As a production example of such an oil-soluble additive, for example, a phosphorus-based additive and the above nitrogen-containing compound are preferably 15 to 150 ° C., preferably 30 to 120 in an organic solvent such as hexane, toluene, decalin and the like. ℃, particularly preferably at 40 to 90 ° C. for 10 minutes to 5 hours, preferably 20 minutes to 3 hours, particularly preferably 30 minutes to 1 hour to dissolve or react, and the solvent is distilled off by distillation under reduced pressure or the like. can get.

  In order to further improve the performance of the lubricating oil composition of the present invention, any additive commonly used in lubricating oils can be added depending on the purpose. Examples of such additives include wear inhibitors, friction modifiers, viscosity index improvers, corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, antifoaming agents, and colorants. An agent etc. can be mentioned.

  Antiwear agents include, for example, disulfides, sulfurized olefins, sulfurized fats and oils, dithiophosphoric acid metal salts (zinc salts, molybdenum salts, etc.), dithiocarbamic acid metal salts (zinc salts, molybdenum salts, etc.), dithiophosphates and their derivatives (olefins). Reaction products with cyclopentadiene, (methyl) methacrylic acid, propionic acid, etc .; in the case of propionic acid, those added to the β-position are preferred.), Sulfur-containing compounds such as trithiophosphates and dithiocarbamates. These can usually be contained in the range of 0.005 to 5% by mass as long as the performance of the composition of the present invention is not significantly impaired, but from the viewpoint of low sulfur and long drain properties, the content thereof Is a sulfur conversion value, preferably 0.1% by mass or less, and more preferably 0.05% by mass or less.

  As the friction modifier, any compound usually used as a friction modifier for lubricating oils can be used. For example, molybdenum-based friction modifier such as molybdenum disulfide, molybdenum dithiocarbamate, molybdenum dithiophosphate, carbon number 6 An amine compound, a fatty acid ester, a fatty acid amide, a fatty acid, a fatty alcohol, a fat having at least one alkyl group or alkenyl group of -30, in particular, a straight-chain alkyl group or straight-chain alkenyl group having 6 to 30 carbon atoms in the molecule. Ashless friction modifiers such as group ethers, hydrazides (eg oleyl hydrazide), semicarbazides, ureas, ureidos, biurets and the like. The content of these friction modifiers is usually 0.1 to 5% by mass.

  As the viscosity index improver, specifically, a so-called non-dispersed viscosity index improver such as a polymer or copolymer of one or more monomers selected from various methacrylates or a hydrogenated product thereof, Or a so-called dispersion-type viscosity index improver obtained by copolymerizing various methacrylic esters containing a nitrogen compound, a non-dispersion type or a dispersion type ethylene-α-olefin copolymer (propylene, 1-butene, 1 -Pentene, etc.) or a hydride thereof, polyisobutylene or a hydrogenated product thereof, a hydride of a styrene-diene copolymer, a styrene-maleic anhydride copolymer, and a polyalkylstyrene.

  The molecular weight of these viscosity index improvers needs to be selected in consideration of shear stability. Specifically, the number average molecular weight of the viscosity index improver is usually 5,000 to 1,000,000, preferably 100,000 to 900,000 in the case of dispersed and non-dispersed polymethacrylates, for example. In the case of polyisobutylene or a hydride thereof, usually 800 to 5,000, preferably 1,000 to 4,000, and in the case of an ethylene-α-olefin copolymer or a hydride thereof, usually 800 to 500. 3,000, preferably 3,000 to 200,000 are used.

  Further, among these viscosity index improvers, when an ethylene-α-olefin copolymer or a hydride thereof is used, a lubricating oil composition particularly excellent in shear stability can be obtained. One or two or more compounds arbitrarily selected from the above viscosity index improvers can be contained in any amount. The content of the viscosity index improver is usually 0.1 to 20% by mass based on the lubricating oil composition.

  Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiadiazole, and imidazole compounds.

  Examples of the rust inhibitor include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester.

  Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.

  Examples of metal deactivators include imidazoline, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis. Examples include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and β- (o-carboxybenzylthio) propiononitrile.

  Examples of the antifoaming agent include silicone, fluorosilicol, and fluoroalkyl ether.

  When these additives are contained in the lubricating oil composition of the present invention, the content is based on the total amount of the lubricating oil composition, and 0.005 to 5% by mass for each of the corrosion inhibitor, rust inhibitor, and demulsifier. The metal deactivator is usually selected in the range of 0.005 to 1% by mass, and the defoamer is usually selected in the range of 0.0005 to 1% by mass.

  In the lubricating oil composition of the present invention, the lubricating oil base oil, the organic molybdenum compound, the aromatic compound represented by the general formula (1), and various additives used as necessary, A low-sulfur lubricating oil composition having an excellent long drain property having a sulfur content of 0.3% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less is also possible.

  In addition, in order to enhance the long drain property of the lubricating oil composition of the present invention and reduce the adverse effects on the exhaust gas aftertreatment device as much as possible, the types and contents of additives containing organic molybdenum compounds and other metals are optimized. Therefore, the sulfated ash content of the composition is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, more preferably 0.6% by mass or less, and 0.5% by mass. % Or less is particularly preferable. Here, the sulfated ash is JIS K 2272 5. The value measured by the method specified in “Testing method for sulfated ash” is mainly attributable to the metal-containing additive.

  The lubricating oil composition of the present invention has excellent long drain properties (oxidation stability, base number maintenance, high temperature cleanability, and resistance to NOx). Therefore, it can be preferably used as a lubricating oil for internal combustion engines such as motorcycles, automobiles, power generation, marine gasoline engines, diesel engines, gas engines, etc. Suitable for an internal combustion engine equipped with Also, low sulfur fuel, for example, gasoline, light oil or kerosene having a sulfur content of 50 mass ppm or less, more preferably 30 mass ppm or less, particularly preferably 10 mass ppm or less, or fuel having a sulfur content of 1 mass ppm or less (LPG). , Natural gas, hydrogen substantially free of sulfur, dimethyl ether, alcohol, GTL (gas-liquid) fuel, and the like).

  Further, the lubricating composition of the present invention is a lubricating oil that requires oxidation stability, such as a lubricating oil for a drive system such as an automatic or manual transmission, grease, wet brake oil, hydraulic fluid, turbine oil. Also, it can be suitably used as a lubricating oil such as compressor oil, bearing oil, and refrigerator oil.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.
[Examples 1 to 5, Comparative Examples 1 to 4]
In Examples 1 to 5 and Comparative Examples 1 to 4, lubricating oil compositions having the compositions shown in Tables 1 and 2 were prepared using the lubricating base oil and additives shown below, respectively. Tables 1 and 2 also show the sulfur content, the phosphorus content, and the molybdenum content (all in terms of element) of the lubricating oil compositions obtained in each Example or Comparative Example.
(Base oil)
Base oil 1: poly α-olefin (kinematic viscosity at 100 ° C .: 6.0 mm ² / s, polycyclic aromatic content: less than 0.001 mass%, total aromatic content: less than 0.1 mass%, sulfur content: (Less than 0.01% by mass)
Base oil 2: hydrocracked mineral oil (kinematic viscosity at 100 ° C .: 5.3 mm ² / s, viscosity index: 120, polycyclic aromatic content: 0.04 mass%, total aromatic content: 5.0 mass%, Sulfur content: less than 0.01% by mass)
(Organic molybdenum compounds)
A1: Ditridecylamine complex of molybdenum (molybdenum content: 9.7% by mass, sulfur content: 0% by mass)
(Aromatic compound represented by general formula (1))
B1: 4-octylphenol (molecular weight: 178)
B2: Hexadecylphenol (molecular weight: 318)
B3: Hexadecyl catechol (molecular weight: 334)
B4: 4-octylaniline (molecular weight: 179)
(Phosphorus additive)
C1: di-n-butyl zinc phosphate (phosphorus content: 13.2% by mass, sulfur content: 0% by mass, zinc content: 13% by mass)
(Metal-based detergent)
D1: Calcium sulfonate (base number: 300 mg KOH / g, calcium content: 11.9% by mass, sulfur content: 1.7% by mass, metal ratio: 10)
(Ashless dispersant)
E1: Mixture of polybutenyl succinimide (number average molecular weight of polybutenyl group: 1300, nitrogen content: 1.8% by mass) and its boride (boron content: 0.77% by mass) (mass ratio 1: 4) .

Next, the following tests were conducted using the lubricating oil compositions of Examples 1 to 3 and Comparative Examples 1 to 4.
[NOx absorption test]
Changes in the base number (hydrochloric acid method) and the acid value over time were measured when a NOx-containing gas was blown into the test oil by a method based on the Japanese Tribology Conference Proceedings 1992, 10, 465 and forcedly deteriorated. The test temperature in this test was 140 ° C., and the NOx concentration in the NOx-containing gas was 1185 ppm. Tables 1 and 2 show the base values and acid values 40 hours after the start of NOx gas blowing. In the table, the smaller the base number decrease or the smaller the acid number increase, the higher the base number maintaining performance even in the presence of NOx used in internal combustion engines, and the longer drain oil that can be used for a longer time. It is shown that.

Claims (4)

Lubricating oil base oil, organic molybdenum compound not containing sulfur as a constituent element, aromatic compound having a structure represented by the following general formula (1), phosphorus-based additive, metal-based detergent, ashless component A lubricating oil composition containing a powder ,
The phosphorus-based additive is a phosphorus compound represented by the following general formula (2), a phosphorus compound represented by the following general formula (3), and metal salts thereof (excluding molybdenum salts) or amine salts. A lubricating oil composition, which is at least one phosphorus-based additive selected .

[In the formula, A represents an aromatic ring, X represents an OH group, R represents a linear or branched alkyl group having 4 to 30 carbon atoms (excluding a tert-butyl group), a represents an integer of 1 or more, and b represents an integer of 1 or more. ]

[Wherein, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, R ² and R ³ may be the same or different, and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; ¹ , X ² and X ³ may be the same or different and each represents an oxygen atom or a sulfur atom, n represents 0 or 1, and when n is 0 , at least one of X ² or X ³ is oxygen An atom, and when n is 1 , at least one of X ¹ , X ² or X ³ is an oxygen atom. ]

[Wherein, R ⁴ represents a hydrocarbon group having 1 to 30 carbon atoms, R ⁵ and R ⁶ may be the same or different, and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; ^{4, X} 5, ^{X 6} and ^{X 7} may be the same or different, each represents an oxygen atom or a sulfur atom, n represents 0 or 1, n is of ^X 5, ^{X 6} or ^{X 7} when 0 At least two of them are oxygen atoms, and when n is 1, at least three of X ⁴ , X ⁵ , X ⁶ or X ⁷ are oxygen atoms. ]   The lubricating oil composition according to claim 1, wherein the lubricating oil composition is used in an internal combustion engine in which a fuel having a sulfur content of less than 100 mass ppm is used.   The lubricating oil composition according to claim 1 or 2, wherein a sulfur content of the lubricating base oil is 0.005 mass% or less based on the total amount of the lubricating base oil.   The organic molybdenum compound is at least one selected from a molybdenum-amine complex, a molybdenum-succinimide complex, a molybdenum salt of an organic acid, and a molybdenum salt of an alcohol. The lubricating oil composition according to any one of the above.