JP4963558B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition suitably used in the field of internal combustion engine or transmission lubricating oil.

  In the field of lubricating oil used in internal combustion engines, transmissions, etc., demands for longer drains of lubricating oil are increasing from the viewpoint of effective utilization of resources in recent years, reduction of waste oil, cost reduction of lubricating oil users, etc. .

  Therefore, in conventional lubricating oils, in order to meet the above requirements, reaction of phenol-based or amine-based antioxidants or the like with highly refined base oils such as mineral oil or synthetic oil whose aromatic content has been reduced by highly refined treatment. By incorporating a large amount of a sulfur-containing compound having a peroxide resolution such as a chain terminator, zinc dithiophosphate (ZDTP), molybdenum dithiocarbamate (MoDTC), etc., the antioxidant property of the lubricating oil is improved (for example, , See Patent Document 1).

  However, when using a large amount of a sulfur-containing compound such as the above-mentioned lubricating oil, it is necessary to achieve a practically sufficient long drain, that is, antioxidation property, base number maintenance property, high temperature cleanability and NOx. It is difficult to sufficiently improve all of the resistance.

In view of this, studies have been made to reduce the content of the above-described sulfur-containing compound or to achieve a long drain without using it. For example, Patent Document 2 discloses a lubricating oil that has improved properties such as wear prevention, base number maintenance, and high-temperature cleanliness by using a thiophosphate ester or phosphate ester or a salt thereof. .
JP-A-8-302378 JP 2002-294271 A

  In the case of the lubricating oil described in Patent Document 2, since the content of sulfur-containing additives such as ZDTP can be reduced or not used, the drain oil has a longer drain than the lubricating oil described in Patent Document 1. This is advantageous. However, according to the study of the present inventor, even in the case of the lubricating oil described in Patent Document 2, in order to achieve a practically sufficient long drain, further improvement particularly in terms of acid value increase suppression. Turned out to be necessary

  This invention is made | formed in view of such a situation, and it aims at providing the lubricating oil composition which is excellent in acid value increase inhibitory property and can achieve sufficient long drain formation.

  As a result of intensive studies to achieve the above object, the present inventor mixed two types of lubricating base oils each containing a specific amount of total aromatics, and contained sulfur as a constituent element in the mixed base oil. The present inventors have found that the above problems can be solved by a lubricating oil composition containing no organic tungsten compound, and have completed the present invention.

That is, the lubricating oil composition of the present invention includes a first lubricating base oil having a total aromatic content of 20 to 100% by mass, a second lubricating base oil having a total aromatic content of 10% by mass or less, And a ratio of the first lubricating base oil to the total amount of the first lubricating base oil and the second lubricating base oil is 5 to 90% by mass. It is characterized by that.

  In the present invention, the “total aromatic content” means the content of an aromatic fraction measured according to ASTM D2549. Usually, this aromatic fraction includes alkylbenzene, alkylnaphthalene, anthracene, phenanthrene and alkylated products thereof, compounds in which four or more benzene rings are condensed, pyridines, quinolines, phenols, naphthols, etc. Compounds having a heteroaromatic ring are included.

  According to the lubricating oil composition of the present invention, by using the first lubricating base oil, the second lubricating base oil and the organic tungsten compound in combination, the antioxidant property, the acid value increase inhibitory property, the base Price maintenance, high temperature cleanliness, and resistance to NOx can be achieved at a high level in a well-balanced manner, and in particular, the first lubrication can be achieved as compared with the case where only the second lubricating base oil is used as the lubricating base oil. By using the oil base oil and the second lubricating oil base oil in combination, the acid value increase inhibitory property can be dramatically improved. Such an effect of the present invention can be said to be an extremely unexpected effect in view of the prior art level in which it is desirable to reduce the aromatic content of the lubricating base oil as much as possible by highly refined treatment or the like.

  Moreover, the lubricating oil composition of the present invention can be suitably used for an internal combustion engine in which a fuel having a sulfur content of 50 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 Therefore, it is possible to achieve an extremely high level of acid number increase inhibitory property, base number maintainability, high temperature cleanability and resistance to NOx. Therefore, the lubricating oil composition of the present invention and the low sulfur fuel are applied to an internal combustion engine. By using it, the benefits (exhaust gas purification, longer life of catalyst, longer drain of lubricating oil, cost / waste oil reduction and resource saving, etc. based on them) can be maximized. .

  The organic tungsten compound contained in the lubricating oil composition of the present invention includes an organic tungsten compound containing no sulfur as a constituent element, and an organic tungsten compound containing sulfur as a constituent element such as tungsten dithiocarbamate (a sulfur-containing organic tungsten compound). However, organic tungsten compounds containing no sulfur as a constituent element are preferable from the viewpoint of lowering sulfur and further improving long drain performance, and tungsten-amine complexes, tungsten salts of organic acids and tungsten salts of alcohols. More preferably, at least one selected from the group consisting of:

Further, in the lubricating oil composition of the present invention, various additives containing sulfur as a constituent element can be contained unless the effect of the present invention is significantly inhibited, but the content is based on the total amount of the composition. It is preferable that it is 0.2 mass% or less in terms of sulfur element. Here, the “additive containing sulfur as a constituent element” includes, in addition to an organic tungsten compound containing sulfur as a constituent element, an organic molybdenum compound containing sulfur as a constituent element, a general formula (3-a) or ( 3-b) a phosphorus compound in which part or all of X ^{5 to} X ¹¹ is a sulfur atom, or a metal salt or amine salt thereof, ZDTP, a metal salt of dithiophosphate, a dithiocarbamate ester or a metal salt thereof, sulfurized oil or fat, disulfide And sulfur-containing antiwear agents such as sulfurized olefins. In addition, these sulfur-containing additives may be blended as a mixture of diluent oil or the like, but "content of additives containing sulfur as a constituent element" is the active ingredient excluding diluent oil and the like Means content. Furthermore, “the content of the additive containing sulfur as a constituent element is 0.2% by mass or less in terms of sulfur element based on the total amount of the composition” means that the lubricating oil composition of the present invention is configured. This means that the total amount of sulfur contained in the components other than the lubricating base oil and the diluent oil of the additive is 0.2% by mass or less in terms of elemental sulfur, based on the total amount of the composition. , [(Sulfur content of the whole composition) − (sulfur content derived from lubricating base oil and diluent oil)] (unit: mass%).

  In the lubricating oil composition of the present invention, the sulfur content of the lubricating base oil is preferably 0 to 0.4 mass%, more preferably 0.05 to 0.35 mass, based on the total amount of the lubricating base oil. %, More preferably 0.1 to 0.3% by mass. By using the lubricating base oil whose sulfur content satisfies the above conditions, the above-described effects of the present invention can be achieved at a higher level.

  The “sulfur content” in the present invention means JIS K 2541-4 “radiation type excitation method” (usually in a range of 0.01 to 5% by mass) or JIS K 2541-5 “bomb type mass method, attached. Value (standard), inductively coupled plasma emission method "(usually 0.05% by mass or more), and the content in terms of sulfur element of an additive containing sulfur as a constituent element Is obtained by measuring [the sulfur content of the entire lubricating oil composition] and [the sulfur content derived from the lubricating base oil and diluent oil], respectively, and subtracting the latter measured value from the former 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 the active ingredient is sulfur in accordance with the above method. There is a way to measure minutes.

  Separation of the active ingredient in the lubricating oil composition or additive from the lubricating base oil and diluent oil can be performed by conventional methods such as rubber membrane dialysis and chromatography (for example, Yagishita et al. 41 卷 No. 4, pp. 25-34 (issued October 1999)). 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.

  As described above, the lubricating oil composition of the present invention can achieve a high level of good balance between antioxidant properties, acid value increase inhibitory properties, base number maintainability, high temperature cleanability and resistance to NOx, and in particular. In addition, since it has excellent acid value increase inhibitory properties, a sufficiently long drain can be realized by the lubricating oil composition of the present invention.

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

  The lubricating oil composition of the present invention includes a first lubricating base oil having a total aromatic content of 20% by mass or more, a second lubricating base oil having a total aromatic content of 10% by mass or less, and an organic tungsten compound. Containing.

  As the first lubricating base oil, the following mineral base oil or synthetic base 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, Of the base oils that have been refined by one or more treatments such as solvent dewaxing, hydrorefining, etc., or base oils produced by the isomerization of wax isomerized mineral oil or GTL WAX (gas to liquid wax), etc. Those having an aromatic content of 20% by mass or more can be used. Among these mineral oil-based base oils, solvent refined mineral oil obtained by performing solvent refining treatment such as solvent deburring, solvent extraction, and solvent dewaxing is preferable.

  When a mineral base oil is used as the first lubricating base oil, the total aromatic content is 20 to 100% by mass, preferably 25 to 100% as described above, based on the total amount of the mineral oil base oil. %, More preferably 28 to 100% by mass. When the total aromatic content of the first lubricating base oil is less than 20% by mass, the long drain property improving effect due to the combination of the second lubricating base oil and the organic tungsten compound tends to be insufficient.

  The upper limit of the total aromatic content of the first lubricating base oil is not particularly limited, but mineral oil having a total aromatic content of 20 to 40% by mass can be expected from the availability and the stability improvement effect by refining. A base oil is more preferable, and a mineral oil base oil of 25 to 35 mass% is more preferable.

  In addition, when a mineral base oil is used as the first lubricating base oil, the breakdown of total aromatics, that is, the content of monocyclic aromatics and polycyclic aromatics is not particularly limited, but a higher level. From the viewpoint of achieving a long drain property, the polycyclic aromatic content is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the total amount of the mineral oil base oil. It is more preferable that it is 1 mass% or more. Further, from the viewpoint of high temperature cleanliness, the polycyclic aromatic content of the mineral oil base oil is preferably 20% by mass or less, more preferably 10% by mass or less, and more preferably 5% by mass based on the total amount of the mineral oil base oil. The following is more preferable, and 2% by mass or less is particularly preferable.

  On the other hand, the monocyclic aromatic content of the mineral base oil as the first lubricating base oil is preferably 40% by mass or less, more preferably 30% by mass or less, based on the total amount of the mineral oil base oil. When the monocyclic aromatic component of the mineral oil base oil exceeds the upper limit, the viscosity index of the lubricating oil composition tends to be low.

  In the present invention, “polycyclic aromatic moiety” and “monocyclic aromatic moiety” refer to Hirsch, D. et al. E. , Anal. Chem. , 44, p915 (1972) means a polycyclic aromatic component and a monocyclic aromatic component measured in accordance with the method disclosed below (the same applies hereinafter).

  Further, when a mineral base oil is used as the first lubricating base oil, the sulfur content is not particularly limited, but is preferably 0.05% by mass or more, and 0.1% by mass or more. Is more preferably 0.2% by mass or more, particularly preferably 0.4% by mass or more, and preferably 1% by mass or less, and 0.9% by mass or less. It is more preferable that the content is 0.8% by mass or less. By using a mineral oil base oil that has a slightly higher sulfur content and a low refining cost such as desulfurization, the long drain property is improved by the sulfur compound that is originally contained in the mineral oil base oil. A lubricating oil composition advantageous in terms of properties can be obtained. On the other hand, when priority is given to reducing sulfur in consideration of the influence on the exhaust gas purification treatment apparatus in the present invention, it is preferable to use a mineral oil base oil having a sulfur content of less than 0.2% by mass. It is more preferable to use a mineral oil base oil of 0.15% by mass or less.

  On the other hand, as the synthetic base oil as the first lubricating base oil, specifically, alkylbenzene, alkylnaphthalene, anthracene, phenanthrene and alkylated products thereof, compounds in which four or more benzene rings are condensed, and pyridines And aromatic synthetic oils such as compounds having a heteroaromatic ring such as quinolines, phenols and naphthols. A mixed base oil of these aromatic synthetic oils and other synthetic oils having a total aromatic content of 20% by mass or more can also be used. By using the above synthetic oil substantially free of sulfur as the lubricating base oil, the sulfur content of the lubricating base oil of the present invention is preferably 0.05% by mass or less, more preferably 0.01% by mass or less. More preferably, it can be 0.005% by mass or less, particularly preferably 0.001% by mass or less, and a lubricating oil composition containing low sulfur or substantially no sulfur can also be obtained.

  In the present invention, as the first lubricating base oil, one of those mineral base oils or synthetic base oils having a total aromatic content of 20% by mass or more is used alone, or two or more kinds are mixed. Can be used. Further, if the total aromatic content of the mixed base oil is 20% by mass or more, a base oil having a total aromatic content of 20% by mass or more and a base oil having a total aromatic content exceeding 10% by mass and less than 20% by mass The mixed base oil may be used as the first lubricating base oil. Furthermore, a lubricating base oil in which an aromatic compound is added to a lubricating base oil having a total aromatic content of more than 10% by mass and less than 20% by mass and a total aromatic content of 20% by mass or more may be used. . The aromatic compounds to be added include alkylbenzene, alkylnaphthalene, anthracene, phenanthrene and alkylated products thereof, compounds in which four or more benzene rings are condensed, and heterogeneous compounds such as pyridines, quinolines, phenols and naphthols. A compound having an aromatic ring is preferred.

The kinematic viscosity of the first lubricating base oil is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 50 mm ² / s or less, more preferably 25 mm ² / s or less, and still more preferably. 15 mm ² / s or less. On the other hand, the kinematic viscosity at 100 ° C. of the lubricating base oil is preferably 4 mm ² / s or more, more preferably 5 mm ² / s or more. When the kinematic viscosity at 100 ° C. of the first lubricating base oil exceeds the upper limit value, the low-temperature viscosity characteristics deteriorate, whereas when the kinematic viscosity is less than the lower limit value, an oil film is formed at the lubricating location. Is inadequate in lubricity, and the evaporation loss of the lubricating base oil is increased.

  Further, the viscosity index of the first lubricating base oil is not particularly limited, but the value is preferably 50 to 120, and preferably 80 to 105 so that excellent viscosity characteristics from low temperature to high temperature can be obtained. Is more preferable, and it is still more preferable that it is 90-98. When the viscosity index of the lubricating base oil is less than the lower limit, the low temperature viscosity characteristics tend to deteriorate.

  Further, the evaporation loss amount of the first lubricating base oil is preferably NOACK evaporation amount of 25% by mass or less, more preferably 16% by mass or less, and more preferably 10% by mass or less. Particularly preferred. When the NOACK evaporation amount of the lubricating base oil exceeds the upper limit, not only the evaporation loss of the lubricating oil is large, but also when used as a lubricating oil for an internal combustion engine, 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. The NOACK evaporation amount in the present invention is measured in accordance with ASTM D5800 (the same applies hereinafter).

  On the other hand, as the second lubricating base oil, the following mineral oil base oil or synthetic base 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, Refined by one or more treatments such as solvent dewaxing, hydrorefining, etc., or base oils produced by isomerizing wax isomerized mineral oil, GTL WAX (Gas Liquid Liquid or Fischer-Tropsch Wax), etc. Among them, those having a total aromatic content of 10% by mass or less can be used.

  As the second lubricating base oil according to the present invention, among the mineral base oils and synthetic base oils, the lubricating oil obtained by subjecting the atmospheric residual oil obtained by atmospheric distillation to vacuum distillation. Hydrocracked mineral oil obtained by hydrocracking the fraction is preferred.

Preferred examples of the method for producing hydrocracked mineral oil include vacuum distillation distillate (WVGO), WVGO mild hydrocracking (MHC) treated oil, debris oil (DAO), DAO MHC treated oil, or a mixed oil thereof. In the presence of a hydrocracking catalyst under the reaction conditions of a total pressure of 150 kg / cm ² or less, a temperature of 360 to 440 ° C., and a LHSV of 0.5 hr ⁻¹ or less so that the decomposition rate is 40% by weight or more. The product may be used as it is or after the lubricating fraction is separated and recovered and then dewaxed and then dearomatized or dearomatized and then dewaxed.

  When a mineral base oil is used as the second lubricating base oil, the total aromatic content must be 10% by mass or less as described above, preferably based on the total amount of the mineral base oil, and preferably It is 0.1-10 mass%, More preferably, it is 1-8 mass%, More preferably, it is 3-8 mass%, Most preferably, it is 4-7 mass%. By making the total aromatic content of the second lubricating base oil within the above range, when the content of the first lubricating base oil is small, the long drain property improving effect according to the present invention, in particular, the acid value is increased. Inhibiting effect can be obtained at a high level, and when a monocyclic aromatic synthetic oil such as alkylbenzene is used as the first lubricating oil base oil, a higher level of long drain property improvement effect, particularly an increase in acid value An inhibitory effect can be obtained.

  In the present invention, a lubricating base oil having a total aromatic content of less than 1% by mass can also be used as the second lubricating base oil, but the first lubricating used in combination with such a lubricating base oil. The oil base oil is preferably a mineral base oil having a total aromatic content of 20 to 100% by mass. When a mineral base oil having a total aromatic content of 20 to 100% by mass and a lubricating base oil having a total aromatic content of less than 1% by mass are used in combination, a monocyclic aromatic synthetic oil such as alkylbenzene and the total aromatic content However, it is possible to obtain a higher long drain property improvement effect, especially an acid value increase suppression effect than when a lubricant base oil of less than 1% by mass is used in combination.

  When a mineral base oil is used as the second lubricating base oil, the breakdown of total aromatics, that is, the content of monocyclic aromatics and polycyclic aromatics is not particularly limited. From the viewpoint of achieving the effect of suppressing the increase in acid value, particularly the acid value, the polycyclic aromatic component is preferably 0.01% by mass or more, preferably 0.03% by mass or more, based on the total amount of the mineral oil base oil. Is more preferable, and it is more preferable that it is 0.04 mass% or more. Moreover, the polycyclic aromatic content of the mineral oil base oil is 2% by mass based on the total amount of the mineral oil base oil from the point that the effect of combined use with the high temperature cleanliness and the first lubricating base oil increases. The following is preferable, and 0.5% by mass or less is more preferable.

  In the present invention, a lubricating base oil having a polycyclic aromatic content of less than 0.01% by mass can be used as the second lubricating base oil. The first lubricating base oil used in combination is preferably a mineral oil system having a polycyclic aromatic content of 0.01 to 100% by mass, more preferably 1 to 100% by mass, and particularly preferably 2 to 100% by mass. Or a synthetic base oil is preferable. When a mineral oil base oil having a polycyclic aromatic content of 0.01 to 100% by mass and a mineral oil system and / or a synthetic base oil having a polycyclic aromatic content of less than 0.01% by mass are used in combination, a unit such as alkylbenzene is used. Higher drainage improvement effect, especially acid value increase suppression effect than when combined with a ring aromatic synthetic oil and a mineral oil system and / or a synthetic base oil having a polycyclic aromatic content of less than 0.01% by mass Obtainable.

  On the other hand, the monocyclic aromatic component of the mineral base oil as the second lubricating base oil is preferably 10% by mass or less, more preferably 7% by mass or less, based on the total amount of the mineral oil base oil. When the monocyclic aromatic component of the mineral oil base oil exceeds the upper limit, the combined effect with the first lubricating base oil tends to be small.

  Further, when a mineral base oil is used as the second lubricating base oil, the sulfur content is not particularly limited, but is preferably 0.05% by mass or less, and 0.01% by mass or less. Is more preferably 0.005% by mass or less, and particularly preferably 0.001% 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.

  On the other hand, as the synthetic base oil as the second lubricating base oil, specifically, polybutene or a hydride thereof; poly-α-olefin such as a 1-octene oligomer or 1-decene oligomer or a hydride thereof; Diesters such as ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, and di-2-ethylhexyl sebacate; neopentyl glycol ester, trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol Polyol ester such as 2-ethylhexanoate and pentaerythritol pelargonate; a mixture of two or more of the above synthetic base oils; and the above synthetic base oils and other synthetic oils (aromatic synthetic oils, etc.) Mixed base oil with total aromatic content of 1 Or the like can be exemplified mass% or less.

  In the present invention, as the second lubricating base oil, one of those mineral base oils or synthetic base oils having a total aromatic content of 10% by mass or less is used alone, or two or more kinds are mixed. Can be used. Further, if the total aromatic content of the mixed base oil is 10% by mass or less, a base oil having a total aromatic content of 10% by mass or less and a base oil having a total aromatic content exceeding 10% by mass and less than 20% by mass The mixed base oil may be used as the first lubricating base oil.

The kinematic viscosity of the second lubricating base oil is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 20 mm ² / s or less, more preferably 6 mm ² / s or less. On the other hand, the kinematic viscosity is preferably 1 mm ² / s or more, more preferably 3 mm ² / s or more. When the kinematic viscosity at 100 ° C. of the second lubricating base oil exceeds the upper limit value, the low temperature viscosity characteristics deteriorate, whereas when the kinematic viscosity is less than the lower limit value, an oil film is formed at the lubrication point. Is inadequate in lubricity, and the evaporation loss of the lubricating base oil is increased.

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

  Further, the evaporation loss amount of the second lubricating base oil is preferably NOACK evaporation amount of 25% by mass or less, more preferably 20% by mass or less, and more preferably 16% by mass or less. More preferred is 10% by mass or less. When the NOACK evaporation amount of the lubricating base oil exceeds the upper limit, not only the evaporation loss of the lubricating oil is large, but also when used as a lubricating oil for an internal combustion engine, 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.

  In the lubricating oil composition of the present invention, the ratio of the first lubricating base oil to the total amount of the first and second lubricating base oils is preferably 1% by mass or more, and 5 to 90% by mass. %, More preferably 15 to 85% by mass, still more preferably 20 to 80% by mass, and particularly preferably 30 to 80% by mass. When the ratio is less than 1% by mass, the effect of improving the long drain property by the combination of the first and second lubricating base oils and the organic tungsten compound becomes insufficient, and in particular, both high temperature cleanliness and oxidation stability are compatible. Tend to be difficult to do. Moreover, when the ratio exceeds 90% by mass, the viscosity index of the lubricating oil composition tends to be low.

  Further, when a mineral base oil having a sulfur content of 0.2% by mass or more is used as the first lubricating base oil, the first and second lubricating base oils are used in terms of high-temperature cleanliness and low sulfur content. The ratio of the first lubricating base oil to the total amount is preferably 10 to 60% by mass, and more preferably 20 to 50% by mass.

  The total aromatic content after mixing the first and second lubricating base oils is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably based on the total amount of the mixed base oil. It is 10 mass% or more, Most preferably, it is 15 mass% or more. When the total aromatic content of the mixed base oil is less than the lower limit, the long drain property improving effect, particularly the acid value increase suppressing effect due to the combination of the first and second lubricating base oils and the organic tungsten compound becomes insufficient. There is a tendency. Further, the total aromatic content of the mixed base oil is preferably 30% by mass or less, more preferably 25% by mass or less, based on the total amount of the mixed base oil, from the viewpoint that the viscosity index of the lubricating oil composition can be further increased. More preferably, it is 20 mass% or less.

  The total aromatic content after mixing the first and second lubricating base oils, that is, the content of monocyclic aromatics and polycyclic aromatics is not particularly limited, but a higher level of long drain The polycyclic aromatic component is preferably 0.01% by mass or more, more preferably 0.05% by mass or more based on the total amount of the mineral oil base oil. It is more preferable that it is 1 mass% or more. From the viewpoint of high-temperature cleanliness, the polycyclic aromatic content of the mixed base oil is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 2% by mass or less, based on the total amount of the mixed base oil. 1% by mass or less is particularly preferable.

  On the other hand, the monocyclic aromatic content of the mixed base oil of the first and second lubricating base oils is preferably 30% by mass or less, more preferably 25% by mass or less, and more preferably 20% by mass based on the total amount of the mixed base oil. The following is more preferable. When the monocyclic aromatic content of the mixed base oil exceeds the above upper limit, the viscosity index of the lubricating oil composition tends to be low.

  Further, the sulfur content of the mixed base oil of the first and second lubricating base oils is not particularly limited, but is preferably 0.005 to 0.6% by mass, and 0.05 to 0.5% by mass. % Is more preferable, 0.1 to 0.4% by mass is further preferable, and 0.2 to 0.3% by mass is particularly preferable. By setting the sulfur content of the mixed base oil within the above range, it is possible to obtain a lubricating base oil that is advantageous in terms of cost and has improved long drainage due to the sulfur compound inherently contained in the mineral base oil. Furthermore, a low-sulfur or essentially sulfur-free lubricating base oil is selected, and the sulfur content of the mixed base oil is preferably 0.05% by mass or less, more preferably 0.01% by mass or less, and still more preferably 0. When it is used as a lubricating oil for internal combustion engines, a low-sulfur lubricating oil composition that can avoid adverse effects on exhaust gas aftertreatment devices as much as possible is also obtained. Obtainable.

The kinematic viscosity of the mixed base oil of the first and second lubricating base oils 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, more preferably 8 mm ² / s or less. On the other hand, the kinematic viscosity is preferably 3 mm ² / s or more, more preferably 4 mm ² / s or more, and still more preferably 5 mm ² / s or more. When the kinematic viscosity at 100 ° C. of the mixed base oil exceeds the upper limit, the low-temperature viscosity characteristics are deteriorated. On the other hand, when the kinematic viscosity is less than the lower limit, the formation of an oil film at the lubrication point is insufficient. Therefore, the lubricity is inferior, and the evaporation loss of the lubricating base oil is increased, which is not preferable.

  Further, the viscosity index of the mixed base oil of the first and second lubricating base oils is not particularly limited, but the value is preferably 80 or more so that excellent viscosity characteristics can be obtained from low temperature to high temperature. , 95 or more, more preferably 110 or more. When the viscosity index of the lubricating base oil is less than the lower limit, the low temperature viscosity characteristics tend to deteriorate.

  Further, the evaporation loss amount of the mixed base oil of the first and second lubricating base oils is preferably NOACK evaporation amount of 20% by mass or less, more preferably 16% by mass or less. It is particularly preferable that the content is not more than mass%. When the NOACK evaporation amount of the lubricating base oil exceeds the upper limit, not only the evaporation loss of the lubricating oil is large, but also when used as a lubricating oil for an internal combustion engine, 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.

  In the lubricating oil composition of the present invention, an organic tungsten compound is blended with the first and second lubricating base oils. Examples of organic tungsten compounds include organic tungsten compounds that do not contain sulfur as a constituent element, and sulfur-containing tungsten compounds such as tungsten dithiocarbamate. In the present invention, a sulfur-containing organic tungsten compound may be used, but from the viewpoint of lowering sulfur and further improving long drain performance, it is preferable to use an organic tungsten compound that does not contain sulfur as a constituent element.

  Specific examples of the organic tungsten compound containing no sulfur as a constituent element include a tungsten-amine complex, a tungsten-succinimide complex, a tungsten salt of an organic acid, a tungsten salt of an alcohol, and the like. Complexes, tungsten salts of organic acids and alcohols are preferred.

Examples of the tungsten compound constituting the organic tungsten compound containing no sulfur as a constituent element include tungsten oxide (for example, tungsten dioxide), tungsten trioxide or a hydrate thereof (for example, WO ₃ · nH ₂ O), and tungstic acid (for example, Tungstic acid metal salts such as orthotungstic acid (H ₂ WO ₄ ), paratungstic acid, polytungstic acid, isopolytungstic acid, heteropolytungstic acid, etc., alkali metal tungstic acid salts (for example, M ₂ WO4; M is alkali Metal), ammonium tungstate (eg, (NH ₄ ) 2 WO ₄ , (NH ₄ ) ₆ [W ₇ O ₂₄ ] · 4H ₂ O), tungsten halide (eg, WCl ₅ , WCl ₆ , WOCl ₄ , WO ₂ Cl ₂ , WO ₂ Br ₂ , W ₂ O ₃ Cl _6, etc.), tungsten nitride _(e.g., WN _{2, W} 2 N) tungsten compound containing no sulfur and the like. Further, the tungsten compound can be many tungsten compounds having various structures depending on the valence and constituent elements of tungsten other than those exemplified above. Among these tungsten compounds, tetravalent to hexavalent, particularly hexavalent tungsten compounds are preferable from the viewpoint of the yield of the organic tungsten compound. Further, from the viewpoint of availability, among the hexavalent tungsten compounds, tungsten trioxide or a hydrate thereof, tungstic acid, alkali metal tungstate, and ammonium tungstate are preferable.

  The amine compound constituting the tungsten-amine complex is not particularly limited, and specific examples of the nitrogen compound include monoamine, diamine, polyamine, and alkanolamine. 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 tungsten-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 tungsten content in the tungsten-amine complex can be relatively increased, and the effects of the present invention can be further enhanced with a small amount of compounding.

  Further, as the tungsten-succinimide complex, a complex of a tungsten compound containing no sulfur as exemplified in the description of the tungsten-amine complex and a succinimide having an alkyl group or an 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. In addition, 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, tungsten-succinimide is obtained. The tungsten content in the complex can be relatively increased, and the effect of the present invention can be further enhanced with a small amount of the compound.

  Examples of the tungsten salt of an organic acid include salts of a tungsten base such as tungsten oxide or tungsten hydroxide, tungsten carbonate or tungsten chloride exemplified in the description of the tungsten-amine complex with an organic acid. It is done. As the organic acid, a phosphorus compound, a carboxylic acid and a carbamic acid represented by the general formula (3-c) or (3-d) exemplified in the explanation of the phosphorus-based additive in the latter stage, or a derivative thereof is preferable. Here, about the preferable aspect of general formula (3-c) and (3-d) in the tungsten salt of a phosphorus compound, it can be made the same as that of the case of the phosphorus additive mentioned later.

  Moreover, as carboxylic acid which comprises the tungsten 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 tungsten salt of the alcohol include a salt of a tungsten compound containing no sulfur as exemplified in the description of the tungsten-amine complex and an alcohol. The alcohol includes a monohydric alcohol, a polyhydric alcohol, Any of a partial ester or partial ether compound of a monohydric alcohol, a nitrogen compound having a hydroxyl group (alkanolamine, etc.), etc. may be used. Tungstic acid is a strong acid and forms an ester by reaction with alcohol. The ester of tungstic acid and alcohol is also included in the tungsten 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 tungsten-amine complex, and alkanolamides (diethanolamide, etc.) in which the amino group of the alkanol is amidated. Polyethylene glycol stearylamine, polyethylene glycol dioleylamine, hydroxyethyl laurylamine, oleic acid diethanolamide and the like are preferable.

  Moreover, as an organic tungsten compound, a sulfur compound such as carbon disulfide or elemental sulfur is added to the tungsten compound containing no sulfur as the above-described constituent element and the above amine, succinimide, organic acid, alcohol, or the like to react. A sulfur-containing organic tungsten compound such as a tungsten-amine complex, a tungsten-succinimide complex, a tungsten salt of an organic acid, or a tungsten salt of an alcohol can be used. Further, in place of a tungsten compound that does not contain sulfur as a constituent element, a sulfur-containing organic tungsten compound (for example, a sulfur-containing tungsten compound such as a tungsten oxysulfide compound or a tungsten sulfide compound) partially or wholly sulfurized, and the above A sulfur-containing organic tungsten compound obtained by reacting amine, succinimide, organic acid, alcohol or the like may be used. Further, in place of the organic acid, a sulfur-containing organic acid compound such as dithiocarbamic acid, dithiophosphoric acid, sulfonic acid, xanthogenic acid, and derivatives thereof is used. In addition, a tungsten salt of a sulfur-containing organic acid obtained by adding a sulfur source such as carbon disulfide or elemental sulfur and reacting as necessary.

  The dithiocarbamic acid tungsten salt (tungsten dithiocarbamate compound) can have various structures depending on the valence and constituent elements of the tungsten compound. For example, the compound represented by the following general formula (1), more specifically, , Tungsten dithiocarbamate, oxytungsten dithiocarbamate, tungsten oxysulfide dithiocarbamate, tungsten dithiocarbamate, and the like.

［式中、Ｒ^１及びＲ^２はそれぞれ独立に炭素数１〜３０の炭化水素基を示し、Ｘは酸素原子及び／又は硫黄原子を示し、ａは１又は２を示し、ｂは０〜４の整数を示し、ｍは１〜６の整数を示し、ｎは１〜６の整数を示す。］

[Wherein, R ¹ and R ² each independently represent a hydrocarbon group having 1 to 30 carbon atoms, X represents an oxygen atom and / or a sulfur atom, a represents 1 or 2, and b represents 0 to 4] M represents an integer of 1 to 6, and n represents an integer of 1 to 6. ]

  Moreover, although the dithiophosphate tungsten salt (tungsten dithiophosphate compound) may have various structures depending on the valence and constituent elements of the tungsten compound, for example, a tungsten dithiophosphate compound represented by the following general formula (2), More specifically, examples include tungsten dithiophosphate, oxytungsten dithiophosphate, tungsten oxysulfide dithiophosphate, tungsten dithiophosphate, and the like.

［式中、Ｒ^３及びＲ^４はそれぞれ独立に炭素数１〜３０の炭化水素基を示し、Ｘは酸素原子及び／又は硫黄原子を示し、ａは１又は２を示し、ｂは０〜４の整数を示し、ｍは１〜６の整数を示し、ｎは１〜６の整数を示す。］

[Wherein, R ³ and R ⁴ each independently represent a hydrocarbon group having 1 to 30 carbon atoms, X represents an oxygen atom and / or a sulfur atom, a represents 1 or 2, and b represents 0 to 4] M represents an integer of 1 to 6, and n represents an integer of 1 to 6. ]

  In addition, as the sulfonic acid tungsten salt, a sulfonic acid tungsten salt having a hydrocarbon group having 1 to 30 carbon atoms such as tungsten alkyl sulfonate, tungsten alkyl benzene sulfonate, tungsten alkyl naphthalene sulfonate, or the like can be used.

  Moreover, as a xanthogenic acid tungsten salt, the xanthogenic acid tungsten salt which has a C1-C30 hydrocarbon group can be used.

  In addition, as the organic tungsten compound, a compound in which some or all of the sulfur atoms in the molecule in the above dithiocarbamic acid tungsten salt, xanthogenic acid tungsten salt, and dithiophosphoric acid tungsten salt are substituted with oxygen atoms can be used.

  In addition, the C1-C30 hydrocarbon group in the said organotungsten compound is C1-C30 described in description of general formula (4-a) and (4-b) in the term of the phosphorus system additive mentioned later. It is synonymous with the hydrocarbon group.

  Moreover, you may use the polytungstate which is a hydrated polymer compound as an organic tungsten compound. Here, the polytungstate can be used as a colloidal suspension composed of a dispersed phase containing polytungstate and an oil phase containing a dispersion aid and a diluent oil. Dispersing aids include polyalkylene succinic anhydrides, non-nitrogen-containing derivatives of polyalkylene succinic anhydrides, as well as succinimides, carboxylic amides, hydrocarbon monoamines, hydrocarbon polyamines, Mannich bases, phosphonamides, thiophosphones Examples thereof include basic nitrogen compounds selected from the group consisting of amides and phosphorus amides, and mixtures thereof. The diluent oil is not particularly limited as long as it can form a stable emulsion having an aqueous phase containing a polytungstate and a dispersion aid and an oil phase containing a diluent oil. Oil is preferably used.

The method for preparing the colloidal suspension is not particularly limited. For example, a monomer compound containing tungsten (WO ₂ , WO ₃ etc.) and an effective amount capable of at least partially polymerizing the monomer compound. An aqueous solution containing an acid, a dispersant, and a diluent oil are stirred and mixed to form a microemulsion, and the microemulsion is heated to remove water to obtain the desired colloidal suspension. it can. In addition, it is preferable that the aqueous solution in the stirring and mixing step further contains a hydroxide such as an alkali metal hydroxide, an alkaline earth hydroxide, ammonium hydroxide, or thallium hydroxide.

  In the lubricating oil composition of the present invention, the content of the organic tungsten compound is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably, in terms of tungsten element, based on the total amount of the composition. Is 0.04% by mass or more, particularly preferably 0.1% by mass or more, preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and further preferably 0.2% by mass or less. It is. When the content of the organotungsten compound is less than 0.001% by mass in terms of tungsten element, the combination of the organotungsten compound and the first and second lubricating base oils prevents oxidation and increases the acid value. , Base number maintainability, high temperature cleanliness, and resistance to NOx tend to be insufficient, and even if it exceeds 0.5% by mass, the above improvement effect commensurate with the increase in content tends not to be obtained. is there.

In producing the lubricating oil composition of the present invention, the first and second lubricating oils are used as long as the finally obtained lubricating oil composition contains the first and second lubricating base oils and the organic tungsten compound. The order of mixing the oil base oil and the organic tungsten compound or the mixing method thereof is not particularly limited, and for example, they can be mixed in the order shown in the following (A) to (D).
(A) After mixing the organotungsten compound with the first lubricating base oil, the mixture and the second lubricating base oil or the mixed base oil of the first and second lubricating base oils are mixed.
(B) After mixing the organotungsten compound with the second lubricating base oil, the mixture is mixed with the first lubricating base oil or the mixed base oil of the first and second lubricating base oils.
(C) After mixing the first and second lubricating base oils, the mixed base oil and the organic tungsten compound are mixed.
(D) A 1st lubricating base oil, a 2nd lubricating base oil, and an organic tungsten compound are mixed simultaneously.

  Here, the organotungsten compound tends to exhibit higher solubility in the first lubricating base oil than in the second lubricating base oil. Therefore, by mixing the components in the order shown in (A) above, the time required for dissolution of the organic tungsten compound in the base oil can be sufficiently shortened, and the lubricating oil group of the organic tungsten compound can be reduced. Uniformity and stability in oil can be improved.

  It is preferable to perform the mixing process shown to said (A)-(D) under stirring, and 20-100 degreeC is suitable for the temperature conditions at the time of mixing.

  The lubricating oil composition of the present invention may be composed only of the first and second lubricating base oils and the organic tungsten compound, but if necessary, further contains various additives shown below. In each mixing step (A) to (D), a part or all of the first and second lubricating base oils and organic tungsten compounds and various additives may be mixed in advance or simultaneously. Also good.

  The lubricating oil composition of the present invention can further improve the antioxidant property, the acid value increase inhibitory property, the base number maintainability, the high-temperature cleanability and the resistance to NOx, particularly the NOx increase inhibitory property against NOx, It is preferable to further contain an organomolybdenum compound from the viewpoint that a level of long draining can be achieved. The organic molybdenum compound 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.

  Preferable examples of the organic molybdenum compound include a molybdenum-amine complex, a molybdenum-succinimide complex, an organic acid, in which the tungsten atom in the organic tungsten compound described in the section of the organic tungsten compound is replaced with a molybdenum atom. Molybdenum salts of alcohols, molybdenum salts of alcohols, etc. Among them, molybdenum-amine complexes, molybdenum salts of organic acids and molybdenum salts of alcohols are preferable, and sulfur is included as a constituent element from the viewpoint of low sulfur and long drain properties. More preferred are the above organomolybdenum compounds.

  In the lubricating oil composition of the present invention, the content of the organomolybdenum compound is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and still more preferably in terms of molybdenum element based on the total amount of the composition. Is 0.01% by mass or more, preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0.06% by mass or less. When the content of the organomolybdenum compound is less than 0.001% by mass in terms of molybdenum element, the addition of the organomolybdenum compound can prevent oxidation, increase acid value, maintain base number, maintain high temperature, and clean up NOx. The improvement effect of resistance tends to be insufficient, and even if it exceeds 0.2% 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 can further contain a phosphorus-based additive (phosphorus-containing wear inhibitor). Examples of phosphorus additives include phosphorus compounds represented by the following general formula (3-a), phosphorus compounds represented by the following general formula (3-b), and metal salts thereof (however, tungsten salts and molybdenum salts) Or at least one phosphorus-based additive selected from amine salts is preferred.

［式中、Ｒ^５は炭素数１〜３０の炭化水素基を示し、Ｒ^６及びＲ^７はそれぞれ独立に水素原子又は炭素数１〜３０の炭化水素基を示し、Ｘ^１、Ｘ^２及びＸ^３はそれぞれ酸素原子又は硫黄原子を示し、ｐは０又は１を示す。］

[Wherein, R ⁵ represents a hydrocarbon group having 1 to 30 carbon atoms, R ⁶ and R ⁷ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and X ¹ , X ² and X ³ represents an oxygen atom or a sulfur atom, respectively, and p represents 0 or 1. ]

［式中、Ｒ^８は炭素数１〜３０の炭化水素基を示し、Ｒ^９及びＲ^１０はそれぞれ独立に水素原子又は炭素数１〜３０の炭化水素基を示し、Ｘ^４、Ｘ^５、Ｘ^６及びＸ^７はそれぞれ酸素原子又は硫黄原子を示し、ｑは０又は１を示す。］

[Wherein R ⁸ represents a hydrocarbon group having 1 to 30 carbon atoms, R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and X ⁴ , X ⁵ , X ⁶ and X ⁷ each represents an oxygen atom or a sulfur atom, and q represents 0 or 1. ]

Specific examples of the hydrocarbon group having 1 to 30 carbon atoms represented by R ^{5 to} R ¹⁰ in the general formulas (3-a) and (3-b) include an alkyl group, a cycloalkyl group, and an alkenyl group. Groups, alkyl-substituted 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).

The hydrocarbon group having 1 to 30 carbon atoms represented by R ^{5 to} R ¹⁰ is preferably an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 24 carbon atoms, and 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 (3-a) include phosphorous acid monoester, monothiophosphorous acid monoester, and dithiophosphorous acid monoester having one hydrocarbon group having 1 to 30 carbon atoms. Ester, (hydrocarbyl) phosphonous acid, (hydrocarbyl) monothiophosphonous acid, (hydrocarbyl) dithiophosphonic acid; phosphorous diester having two hydrocarbon groups having 1 to 30 carbon atoms, monothiophosphorous diester, dithio Phosphorous acid diester, (hydrocarbyl) phosphonous acid monoester, (hydrocarbyl) monothiophosphonous acid monoester, (hydrocarbyl) dithiophosphonous acid monoester; phosphorous having three hydrocarbon groups having 1 to 30 carbon atoms Acid triester, monothiophosphite triester, dithiophosphite triester (Hydrocarbyl) phosphonous acid diesters, (hydrocarbyl) monothio phosphonous acid diester, (hydrocarbyl) dithiophosphoric phosphonous acid diester; and the like and mixtures thereof.

In the present invention, the formula (3-a) a compound represented by, X ¹ at least one compound is an oxygen atom are preferable to X ^3, compounds all X ¹ to X ³ is an oxygen atom, That is, a compound represented by the following general formula (3-c) is more preferable.

［式中、Ｒ^５は炭素数１〜３０の炭化水素基を示し、Ｒ^６及びＲ^７は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜３０の炭化水素基を示し、ｐは０又は１を示す。］

[Wherein, R ⁵ represents a hydrocarbon group having 1 to 30 carbon atoms, R ⁶ and R ⁷ 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-b) include phosphoric acid monoesters, monothiophosphoric acid monoesters, dithiophosphoric acid monoesters having one hydrocarbon group having 1 to 30 carbon atoms (hydrocarbyl). Phosphonic acid, (hydrocarbyl) monothiophosphonic acid, (hydrocarbyl) dithiophosphonic acid; phosphoric acid diester, monothiophosphoric acid diester, dithiophosphoric acid diester having two hydrocarbon groups having 1 to 30 carbon atoms, (hydrocarbyl) phosphonic acid mono Ester, (hydrocarbyl) monothiophosphonic acid monoester, (hydrocarbyl) dithiophosphonic acid monoester; phosphoric acid triester having three hydrocarbon groups having 1 to 30 carbon atoms, monothiophosphoric acid triester, dithiophosphoric acid triester, (Hydrocarbyl) phosphon Diesters, (hydrocarbyl) Monochiohosuhon diester (hydrocarbyl) dithiophosphoric acid diester; and the like and mixtures thereof.

In the present invention, the compound represented by the general formula (3-b), X ⁴ at least two compounds is an oxygen atom are preferable to X ^7, compounds all X ⁴ to X ⁷ is an oxygen atom, That is, a compound represented by the following general formula (3-d) is more preferable.

［式中、Ｒ^８は炭素数１〜３０の炭化水素基を示し、Ｒ^９及びＲ^１０は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜３０の炭化水素基を示し、ｑは０又は１を示す。］

[Wherein R ⁸ represents a hydrocarbon group having 1 to 30 carbon atoms, R ⁹ and R ¹⁰ 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. ]

  In addition, the metal salt or amine salt of the phosphorus compound represented by the general formula (3-a) or (3-b) is converted into the phosphorus compound represented by the general formula (3-a) or (3-b), Metal bases such as metal oxides, metal hydroxides, metal carbonates and metal chlorides, ammonia, nitrogen such as amine compounds having in the molecule only hydrocarbon groups having 1 to 30 carbon atoms or hydroxyl group-containing hydrocarbon groups It can be obtained by allowing a compound or the like to act to neutralize part or all of the remaining 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 tungsten salts). Among these, alkaline earth metals such as calcium and magnesium, molybdenum 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 having one OH group) are reacted, a compound having a structure represented by the following formula (3-e) is considered to be obtained as a main component. It is thought that the molecules that existed exist.

［式中、Ｒはそれぞれ独立に水素原子又は炭素数１〜３０の炭化水素基を示す。］

[In formula, R shows a hydrogen atom or a C1-C30 hydrocarbon group each independently. ]

  For example, when 1 mol of zinc oxide and 1 mol of phosphoric acid monoester (compound having two OH groups) are reacted, a compound having a structure represented by the following formula (3-f) is considered to be obtained as a main component. However, it is thought that polymerized molecules exist.

［式中、Ｒは水素原子又は炭素数１〜３０の炭化水素基を示す。］

[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 tungsten-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 a phosphorus additive concerning this invention, the phosphorus compound represented by the said general formula (3-c) or (3-d) or its metal salt (however, except a tungsten salt) is preferable, and especially carbon number Salts of phosphite diester having two 3 to 18 alkyl groups or aryl groups and zinc or calcium, 3 to 18 alkyl groups or aryl groups, preferably 3 to 6 to 12 alkyl groups Phosphorous acid triester, salt of phosphoric acid monoester having 1 to 3 to 18 carbon atoms or aryl group and zinc or calcium, 2 to 3 to 18 alkyl group or aryl group Phosphoric acid having a salt of a diester of phosphoric acid and zinc or calcium, or an alkyl group or aryl group having 3 to 18 carbon atoms, preferably 3 alkyl groups having 6 to 12 carbon atoms Reester, salt of phosphonous acid and zinc or calcium having one alkyl group or aryl group having 1 to 18 carbon atoms (hydrocarbyl), two alkyl group or aryl group having 1 to 18 carbon atoms (hydrocarbyl) Phosphonic acid monoester and zinc or calcium salt, 3 to 1 alkyl group or aryl group having 1 to 18 carbon atoms (hydrocarbyl) phosphonous acid diester, 1 to 1 carbon group having 1 alkyl group or aryl group (Hydrocarbyl) salt of phosphonic acid and zinc or calcium, salt of (hydrocarbyl) phosphonic acid monoester having two C1-18 alkyl groups or aryl groups, zinc or calcium, alkyl of 1 to 18 carbon atoms (Hydrocarbyl) phosphonic acid diesters having three groups or aryl groups are 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, wear resistance tends to be insufficient. 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. And the lubricating oil composition of this invention does not contain the compound containing sulfur as a phosphorus additive, ie, the phosphorus additive is represented by the general formula (3-c) or (3-d). Most preferably, it is composed only of a compound or a metal salt thereof (excluding a tungsten 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 particularly preferable to use an alkali metal or alkaline earth metal sulfonate from the viewpoint of further suppressing an increase in acid value and viscosity with respect to NOx.

  The metal ratio of the metal-based detergent is not particularly limited, and usually 40 or less, preferably 20 or less can be used, but the metal ratio is preferably from the point that the friction reduction effect and the long drain property can be further improved. It is preferable that it consists of 1 type, 2 types or more chosen from 1-15, more preferably 2-12 metal type detergents. 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.

  In the present invention, it is preferable to use an alkali metal or alkaline earth metal sulfonate from the viewpoint of further suppressing an increase in the acid value with respect to NOx, and an alkali or alkali having a metal ratio of preferably 2 to 20, more preferably 5 to 15. Particular preference is given to using earth metal sulfonates.

  The upper limit of the content of the metal detergent in the lubricating oil composition of the present invention is not particularly limited, but usually the sulfated ash content of the composition is 1.0% by mass or less based on the total amount of the composition. It is preferable to adjust together with other additives. From such a viewpoint, the content of the metallic detergent is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and more preferably 0.3% by mass or less, based on the total amount of the composition in terms of metal element. Preferably it is 0.23 mass% or less. 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.

  Moreover, 0.1-500 are preferable and, as for mass ratio (M / W) of the metal (M) contained in a metal type cleaning agent, and tungsten (W) contained in an organic tungsten compound, 0.5-100 are preferable. More preferably, 1-10 are still more preferable, and 2-5 are especially 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 unpreferable 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 group 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 (4-a) or (4-b).

［式中、Ｒ^１１は炭素数４０〜４００、好ましくは６０〜３５０のアルキル基又はアルケニル基を示し、ｒは１〜５、好ましくは２〜４の整数を示す。］

[Wherein, R ¹¹ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and r represents an integer of 1 to 5, preferably 2 to 4. ]

［式中、Ｒ^１２及びＲ^１３は、それぞれ独立に炭素数４０〜４００、好ましくは６０〜３５０のアルキル基又はアルケニル基、更に好ましくはポリブテニル基を示し、ｓは０〜４、好ましくは１〜３の整数を示す。］

[Wherein, R ¹² and R ¹³ 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 s is 0 to 4, preferably 1 to An integer of 3 is shown. ]

  The succinimide includes a so-called mono-type succinimide represented by the formula (7) in which succinic anhydride is added to one end of the polyamine, and a formula in which succinic anhydride is added to both ends of the polyamine (4- The so-called bis-type succinimide represented by b) is included, but the lubricating oil composition of the present invention may include only one of them or a mixture thereof. Good.

  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 (4-c).

［式中、Ｒ^２１は、炭素数４０〜４００、好ましくは６０〜３５０のアルキル基又はアルケニル基を示し、ｔは１〜５、好ましくは２〜４の整数を示す。］

[Wherein, R ²¹ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and t 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 (4-d).

R ²² —NH— (CH ₂ CH ₂ NH) _u —H (4-d)
[Wherein, R ²² represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and u 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 also in the lubricating oil composition of the present invention, antioxidant properties, acid value increase inhibitory properties, base number maintenance properties, high temperature cleanliness properties. And it is effective to further increase the resistance to NOx.

  In the present invention, when a boron-containing ashless dispersant, particularly a boron-containing succinimide-based ashless dispersant, is used, the mass ratio (B / N ratio) between the boron content and the nitrogen content is not particularly limited, and is usually 0.8. Although it is 01-2, Preferably it is 0.1-1, More preferably, it is 0.2-0.8, More preferably, it is 0.3-0.6, Most preferably, it is 0.3-0.5.

  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 suppressing the increase in the acid value in the presence of NOx is small. On the other hand, when the content exceeds 20% by mass, the low-temperature fluidity of the lubricating oil composition is low. Since it deteriorates significantly, each is not preferable. Further, when the lubricating oil composition of the present invention contains a boron-containing ashless dispersant, the content is preferably 0.005 to 0.2% by mass, more preferably, as the boron content, based on the total amount of the composition. It is 0.01-0.1 mass%, More preferably, it is 0.02-0.04 mass%. By containing a boron-containing ashless dispersant, particularly a boron-containing succinimide in the above range, not only the viscosity increase suppressing effect but also heat resistance and wear resistance can be further improved.

  Moreover, it is preferable that the lubricating oil composition of the present invention further contains a chain termination type antioxidant. Thereby, the antioxidant property of the lubricating oil composition is further improved, and not only the acid value increase suppressing effect in the present invention can be further improved, but also the base number maintaining property, the high temperature cleanability and the resistance to NOx can be further improved.

  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 based on the total amount of the lubricating oil composition in order to further increase the antioxidant property, the acid value increase inhibitory property, the base value maintainability, the high temperature cleanability and the resistance to NOx. It is above, Preferably it is 1 mass% or more.

  The phosphorus-based additive used in the present invention includes a compound that does not dissolve in the lubricating base oil or a compound that has low solubility (for example, zinc dialkyl phosphate that is solid at room temperature). In the case of using such a compound as a nitrogen-containing compound (for example, an amine compound as an ashless dispersant) from the viewpoint of improving the solubility of the phosphorus-based additive in the lubricating base oil and shortening the production time of the lubricating oil composition And amine-based antioxidants or their mixtures as chain-stopping antioxidants) and phosphorus additives are mixed and dissolved or reacted to lubricate the dissolved or reaction products as oil-soluble additives. It is particularly preferable to blend in the oil composition. 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 0.01 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, fluorosilicone, 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 antifoaming agent is usually selected in the range of 0.0005 to 1% by mass.

  In the lubricating oil composition of the present invention, the content of the additive containing sulfur as a constituent component is preferably 0.2% by mass or less as the sulfur content of the active ingredient based on the total amount of the composition. More preferably, it is 0.16% by mass or less, still more preferably 0.1% by mass or less, and particularly preferably 0.05% by mass or less.

  Further, the sulfur content in the lubricating oil composition of the present invention is derived from the sulfur content of the lubricating base oil in addition to the additive containing sulfur as a constituent component. The sulfur content in the composition can be 0.005 to 0.4% by mass, and further includes a lubricating base oil, an organic tungsten compound that does not contain sulfur as a constituent element, and various additives used as necessary. By selection, a sulfur content in the composition is 0.3% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and a low-sulfur composition excellent in long draining properties. Is also possible.

  Further, in order to enhance the long drain property of the lubricating oil composition of the present invention and to reduce the adverse effect on the exhaust gas aftertreatment device as much as possible, an additive containing an organic tungsten compound not containing sulfur as a constituent element and other metals, By optimizing the content, the sulfated ash content of the lubricating oil composition is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, and 0.6% by mass or less. Is more preferable, 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 kinematic viscosity of the lubricating oil composition of the present invention is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 25 mm ² / s or less, more preferably 15 mm ² / s or less. On the other hand, the kinematic viscosity at 100 ° C. is preferably 4 mm ² / s or more, and more preferably 5 mm ² / s or more. When the kinematic viscosity at 100 ° C. of the lubricating oil composition exceeds the upper limit, the low-temperature viscosity characteristics are deteriorated. On the other hand, when the kinematic viscosity is less than the lower limit, the formation of an oil film at the lubricating portion is insufficient. Therefore, the lubricity is inferior and the evaporation loss of the lubricating base oil is increased, which is not preferable.

  Further, the viscosity index of the lubricating oil composition of the present invention is not particularly limited, but the value is preferably 80 or more, and preferably 120 or more so that excellent viscosity characteristics from low temperature to high temperature can be obtained. More preferably, it is 150 or more. When the viscosity index of the lubricating base oil is less than the lower limit, the low temperature viscosity characteristics tend to deteriorate.

  Further, the evaporation loss amount of the lubricating oil composition of the present invention is preferably NOACK evaporation amount of 25% by mass or less, more preferably 20% by mass or less, and more preferably 16% by mass or less. More preferred is 10% by mass or less. When the NOACK evaporation amount of the lubricating oil composition exceeds the upper limit, not only the evaporation loss of the lubricating oil composition is large, but also when used as a lubricating oil for an internal combustion engine, the sulfur compound or phosphorus compound in the composition, or There is a possibility that the metal component is deposited on 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.

  The lubricating oil composition of the present invention has excellent long draining properties (antioxidant property, acid value increase inhibitory property, base number maintainability, high temperature cleanability and resistance to NOx), and particularly excellent acid value increase inhibitory property in the presence of NOx. It is. 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., and especially when exhaust gas is treated with low sulfur and low ash content. It is suitable for an internal combustion engine equipped with the device. 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 4, Comparative Example 1]
In Examples 1 to 4 and Comparative Example 1, lubricating oil compositions having the compositions shown in Table 1 were prepared using the lubricating base oils and additives shown below, respectively.

  Table 1 also shows the sulfur content in the mixed base oil in each example or comparative example, and the tungsten content and sulfur content (both element conversion values) of the lubricating oil composition.

(Lubricant base oil)
Base oil 1: solvent refined mineral oil (kinematic viscosity at 100 ° C .: 4.0 mm ² / s, viscosity index: 100, polycyclic aromatic content: 0.5 mass%, total aromatic content: 22 mass%, sulfur content: 0.09% by mass)
Base oil 2: Solvent refined mineral oil (kinematic viscosity at 100 ° C .: 7.1 mm ² / s, viscosity index: 95, polycyclic aromatic content: 1.0 mass%, total aromatic content: 30 mass%, sulfur content: 0.5% by mass)
Base oil 3: hydrocracked mineral oil (kinematic viscosity at 100 ° C .: 5.3 mm ² / s, viscosity index: 125, polycyclic aromatic content: 0.04 mass%, total aromatic content: 5.0 mass%, Sulfur content: less than 0.0005 mass%)
(Organic tungsten compound)
A1: Tungstic acid ditridecylamine salt (tungsten content: 24.4% by mass, sulfur content: 0% by mass, nitrogen content: 1.8% by mass)
A2: Oxytungsten ditridecyl dithiocarbamate (tungsten content: 29.1% by mass, sulfur content: 6.4% by mass, nitrogen content: 1.8% by mass)
(Metal-based detergent)
B1: Calcium sulfonate (base number: 300 mgKOH / g, calcium content: 11.9% by mass, sulfur content: 1.7% by mass, metal ratio: 10)
(Ashless dispersant)
C1: 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)
(Viscosity index improver)
D1: Ethylene-propylene copolymer-based viscosity index improver (weight average molecular weight: 150,000).

[NOx absorption test]
About each lubricating oil composition of Examples 1-4 and the comparative example 1, the NOx absorption test was implemented as follows.

The change with time of the acid value was measured when NOx-containing gas was blown into the test oil and forcedly deteriorated by a method in accordance with 1992, 10, 465 of the Japanese Tribology Conference Proceedings. The test temperature in this test was 140 ° C., and the NOx concentration in the NOx-containing gas was 1185 ppm. Table 1 shows the increase in acid value after 40 hours from the start of NOx gas blowing. In the table, the smaller the increase in the acid value, the longer the drain oil that can be used for a longer time even in the presence of NOx used in an internal combustion engine.

From the results of Table 1, the lubricating oil compositions of Examples 1 to 4 containing the first and second lubricating base oils and the organotungsten compound according to the present invention did not contain the first lubricating base oil. Compared to the lubricating oil composition of Example 1, it can be seen that the acid value increase suppression effect is excellent. Although not shown in Table 1, the lubricating oil compositions of Examples 1 and 4 were measured together with the change over time in the base number (hydrochloric acid method) in the NOx absorption test. It was confirmed that the composition was superior in the base number maintenance property.

Claims (2)

The first and the lubricating oil base oil a total aromatic content of 20 to 100 wt%, the total aromatic content is contained and a second lubricating base oil of 10 wt% or less, and an organic tungsten compound, the said first The lubricating oil composition, wherein a ratio of the first lubricating base oil to a total amount of the first lubricating base oil and the second lubricating base oil is 5 to 90% by mass . The total aromatic content of the mixed base oil of the first lubricating base oil and the second lubricating base oil is 15% by mass or more and 30% by mass or less based on the total amount of the mixed base oil. The lubricating oil composition according to claim 1.