Lubricant composition

Abstract

Provided is a lubricant composition comprising a base oil (A), a hindered amine compound (B), and organic zinc dithiophosphate (C) having at least one primary alkyl group.

Description

lubricating oil composition

[0001] The present invention relates to a lubricating oil composition, an internal combustion engine filled with said lubricating oil composition, and a method of using said lubricating oil composition.

[0002] In recent years, environmental regulations have become increasingly stringent on a global scale, and regulations on fuel economy and exhaust gas emissions, particularly for automobiles, are becoming increasingly stringent. The background to this is environmental issues such as global warming and the need to protect resources due to concerns about the depletion of oil resources. In light of these recent circumstances, the production rate of hybrid vehicles, which are equipped with both internal combustion engines and electric motors, has increased in order to reduce air pollution caused by automobile exhaust gases. While the lubricating oil used in the internal combustion engines of hybrid vehicles is the same as that used in conventional automobiles powered solely by internal combustion engines, progress is being made in the development of lubricating oils for internal combustion engines that are suited to the operating environment of hybrid vehicles.

[0003] For example, Patent Document 1 discloses a lubricating oil composition for the internal combustion engine of a hybrid vehicle, which contains a 100N hydrorefined mineral oil, a hindered amine compound, an amine-based antioxidant, a metal-based detergent, and an organic zinc dithiophosphate, with the hindered amine compound and the amine-based antioxidant contained in a predetermined ratio.

[0004] JP 2016-180069 A

[0005] In this situation, there is a demand for a lubricating oil composition that has an improved effect of suppressing copper elution and that can be suitably used in an internal combustion engine of a hybrid system having an internal combustion engine and an electric motor as a power source.

[0006] After extensive research, the present inventors have found that the above-mentioned problems can be solved by preparing a lubricating oil composition containing a base oil, a hindered amine compound, and an organic zinc dithiophosphate having at least one primary alkyl group. Specifically, the present invention discloses the following aspects: [1] A lubricating oil composition containing a base oil (A), a hindered amine compound (B), and an organic zinc dithiophosphate having at least one primary alkyl group (C). [2] An internal combustion engine mounted on a hybrid system, filled with the lubricating oil composition described in [1] above. [3] A method for lubricating an internal combustion engine mounted on a hybrid system, using the lubricating oil composition described in [1] above.

[0007] A lubricating oil composition according to a preferred embodiment of the present invention has an excellent effect of inhibiting copper elution and can maintain good long-drain properties for a long period of time. Furthermore, a lubricating oil composition according to a more preferred embodiment of the present invention has excellent high-temperature detergency in addition to the effect of inhibiting copper elution. Because of these properties, the lubricating oil composition according to one embodiment of the present invention can be suitably used for lubricating the internal combustion engine of a hybrid system. Hereinafter, the performance of inhibiting copper elution may also be referred to as copper elution resistance.

[0008] The upper and lower limit values ​​of the numerical ranges described herein can be arbitrarily combined. For example, when a numerical range is described as "preferably 30 to 100, more preferably 40 to 80," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described herein. Furthermore, a numerical range described herein, such as "60 to 100," means a range of "60 or more (more than 60) and 100 or less (less than 100)." Furthermore, in defining the upper and lower limit values ​​described herein, the numerical range from the lower limit value to the upper limit value can be defined by appropriately selecting from the respective options and combining them arbitrarily. In addition, multiple combinations of the various requirements described as preferred aspects in the present specification can be used.

[0009] In this specification, kinematic viscosity and viscosity index refer to values ​​measured and calculated in accordance with JIS K2283:2000. The contents of alkali metals, alkaline earth metals, zinc atoms (Zn), molybdenum atoms (Mo), phosphorus atoms (P), and boron atoms (B) refer to values ​​measured in accordance with JPI-5S-38-92. The content of nitrogen atoms (N) refers to a value measured in accordance with JIS K2609:1998. The base number refers to the base number measured by the hydrochloric acid method in accordance with JIS K2501 "Petroleum products and lubricants - Neutralization number test method".

[0010] [Constitution of Lubricating Oil Composition] The lubricating oil composition of one embodiment of the present invention contains a base oil (A), a hindered amine compound (B), and an organic zinc dithiophosphate having at least one primary alkyl group (C).

[0011] Compared to the internal combustion engines of conventional automobiles, the internal combustion engines of hybrid automobiles, which are equipped with both an internal combustion engine and an electric motor, are often stopped for longer periods of time during use, making condensation more likely to occur in the crankcase. Therefore, lubricating oil compositions used in hybrid systems, such as hybrid automobiles, are prone to moisture contamination, which can lead to a decrease in long-drain properties. However, copper-containing alloys may be used in various components of internal combustion engines. The inventors have found that copper elution from alloys composing various components into a lubricating oil composition can cause corrosion and wear. In order to suppress copper elution, the inventors have conducted extensive research and discovered that the above problem can be solved by using a lubricating oil composition containing a hindered amine compound (B) in combination with an organic zinc dithiophosphate (C) having at least one primary alkyl group. The lubricating oil composition of one embodiment of the present invention was developed based on this finding.

[0012] The lubricating oil composition of one embodiment of the present invention may further contain molybdenum dithiocarbamate (D). The lubricating oil composition of one embodiment of the present invention may further contain an antioxidant (E) that does not fall under component (B). The lubricating oil composition of one embodiment of the present invention may further contain an imide compound (F). The lubricating oil composition of one embodiment of the present invention may further contain a metal-based detergent (G). The lubricating oil composition of one embodiment of the present invention may further contain lubricating oil additives other than the above components (B) to (G), as long as the effects of the present invention are not impaired.

[0013] In the lubricating oil composition of one embodiment of the present invention, the total content of components (A), (B), and (C) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 65 mass% or more, still more preferably 70 mass% or more, and particularly preferably 75 mass% or more, and may also be 100 mass% or less, 99.99 mass% or less, 99.90 mass% or less, 99.50 mass% or less, 99.0 mass% or less, 98.0 mass% or less, 97.0 mass% or less, 95.0 mass% or less, 92.0 mass% or less, or 91.0 mass% or less.

[0014] In the lubricating oil composition of one embodiment of the present invention, the total content of components (A), (B), (C), (D), (E), (F), and (G) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 60 mass% or more, more preferably 65 mass% or more, even more preferably 70 mass% or more, still more preferably 75 mass% or more, and particularly preferably 80 mass% or more, and may also be 100 mass% or less, 99.99 mass% or less, 99.90 mass% or less, 99.50 mass% or less, or 99.0 mass% or less.

[0015] Hereinafter, each component contained in the lubricating oil composition of one embodiment of the present invention will be described in detail.

[0016] <Component (A): Base Oil> In the lubricating oil composition of one embodiment of the present invention, the base oil used as component (A) may be one or more selected from mineral oils and synthetic oils. Examples of mineral oils include atmospheric residues obtained by atmospheric distillation of crude oils such as paraffin-based crude oils, intermediate-based crude oils, and naphthene-based crude oils; distillates obtained by vacuum distillation of these atmospheric residues; and refined oils obtained by subjecting the distillates to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0017] Examples of synthetic oils include poly-α-olefins such as α-olefin homopolymers or α-olefin copolymers (for example, α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffins; polyalkylene glycols; ester-based oils such as polyol esters, dibasic acid esters, and phosphate esters; ether-based oils such as polyphenyl ethers; alkylbenzenes; alkylnaphthalenes; and synthetic oils (GTL) obtained by isomerizing wax produced from natural gas by the Fischer-Tropsch process or the like (GTL wax (Gas To Liquids WAX)).

[0018] Component (A) used in one embodiment of the present invention is preferably one or more selected from mineral oils classified into Group II and Group III of the API (American Petroleum Institute) base oil category and synthetic oils.

[0019] The kinematic viscosity at 40°C of the component (A) used in one embodiment of the present invention is preferably 3.0 to 120 mm ２ / s, more preferably 3.5 to 100 mm ２ / s, more preferably 4.0 to 70 mm ２ / s, and even more preferably 4.5 to 50 mm ２ / s, particularly preferably 5.0 to 30 mm ２ / s.

[0020] The viscosity index of component (A) used in one embodiment of the present invention is preferably at least 70, more preferably at least 90, even more preferably at least 100, still more preferably at least 110, and particularly preferably at least 120. When a mixed oil comprising two or more base oils is used as component (A) in one embodiment of the present invention, the kinematic viscosity and viscosity index of the mixed oil are preferably within the above-mentioned ranges.

[0021] In the lubricating oil composition of one embodiment of the present invention, the content of component (A) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 40 mass% or more, more preferably 50 mass% or more, even more preferably 60 mass% or more, still more preferably 65 mass% or more, and particularly preferably 70 mass% or more. It may also be 75 mass% or more or 80 mass% or more, and may also be 99.4 mass% or less, 99.0 mass% or less, 97.0 mass% or less, 95.0 mass% or less, 92.0 mass% or less, or 90.0 mass% or less.

[0022] <Component (B): Hindered Amine Compound> The lubricating oil composition of one embodiment of the present invention contains a hindered amine compound as component (B). By containing component (B), it is possible to obtain a lubricating oil composition with improved long drain properties. Component (B) used in one embodiment of the present invention may be used alone or in combination of two or more types.

[0023] In one embodiment of the present invention, the hindered amine compound used as component (B) may be a compound containing a structure represented by the following formula (b-0). In the above formula, *1 and *2 indicate the bonding positions to other atoms.

[0024] Component (B) used in one embodiment of the present invention preferably includes at least one compound selected from the group consisting of a compound (B1) represented by the following general formula (b-1) and a compound (B2) represented by the following general formula (b-2):

[0025] In the above general formulas (b-1) and (b-2), R ｂ１ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.ｂ２ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an aryl group having 6 to 18 ring carbon atoms, a hydroxyl group, an amino group, or —O—CO—R ｂ３ A group represented by R ｂ３ In the general formula (b-2), Z represents an alkylene group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 18 ring carbon atoms, an arylene group having 6 to 18 ring carbon atoms, an oxygen atom, a sulfur atom, or —O—CO—(CH ２ ) ｎ It is a group represented by —CO—O— (n is an integer of 1 to 20).

[0026] R ｂ１ Examples of the alkyl group that can be selected as R include a methyl group, an ethyl group, a propyl group (n-propyl group, isopropyl group), a butyl group (n-butyl group, s-butyl group, t-butyl group, isobutyl group), a pentyl group, a hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. The alkyl group may be a linear alkyl group or a branched alkyl group. ｂ１ The alkyl group that can be selected as the alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms.

[0027] R ｂ１ Examples of the alkoxy group that can be selected from include a methoxy group, an ethoxy group, a propoxy group (n-propoxy group, isopropoxy group), a butoxy group (n-butoxy group, s-butoxy group, t-butoxy group, isobutoxy group), a pentyloxy group, a hexyloxy group, a 2-ethylhexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, and -(CH ２ ) ｎ - (n is an integer of 1 to 20). The alkoxy group may be a linear alkoxy group or a branched alkoxy group. ｂ１ The alkoxy group that can be selected as above preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms.

[0028] R ｂ２ The alkyl group that can be selected as R ｂ１ In addition to the above-mentioned alkyl groups having 1 to 10 carbon atoms that can be selected as R, examples thereof include undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl, and octadecyl groups. The alkyl group may be a linear or branched alkyl group. ｂ２ The alkyl group that can be selected as the alkyl group preferably has 1 to 20 carbon atoms, more preferably 3 to 18 carbon atoms, even more preferably 6 to 16 carbon atoms, and even more preferably 8 to 14 carbon atoms.

[0029] R ｂ２ Examples of the cycloalkyl group that can be selected as R include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and an adamantyl group. ｂ２ The cycloalkyl group that can be selected as the cycloalkyl group preferably has 3 to 18 ring carbon atoms, more preferably 5 to 15 ring carbon atoms, and even more preferably 6 to 12 ring carbon atoms.

[0030] R ｂ２ Examples of the aryl group that can be selected as R include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a biphenyl group, a terphenyl group, and a phenylnaphthyl group. ｂ２ The number of ring carbon atoms of the aryl group that can be selected as above is preferably 6 to 18, more preferably 6 to 15, and even more preferably 6 to 12.

[0031] Examples of the alkylene group that can be selected as Z include methylene, 1,1-ethylene, 1,2-ethylene, 1,3-propylene, 1,2-propylene, 2,2-propylene, and other propylene groups, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, and octadecylene groups. Examples of the cycloalkylene group that can be selected as Z include cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, and adamantylene groups. Examples of the arylene group that can be selected as Z include a phenylene group, a naphthylene group, an anthrylene group, a phenanthrylene group, a biphenylene group, and a terphenylene group.

[0032] Component (B) used in one embodiment of the present invention more preferably includes at least one compound selected from the group consisting of compound (B11) represented by general formula (b-11) below and compound (B21) represented by general formula (b-21) below:

[0033] In the above general formulae (b-11) and (b-21), R ｂ１ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. ｂ１ Specific examples of the alkyl group that can be selected as R and the range of the preferred number of carbon atoms are as described above. ｂ３ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. In the above general formula (b-21), n ​​represents an integer of 1 to 20.

[0034] R ｂ３Examples of the hydrocarbon group that can be selected as the alkyl group include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms which may be substituted with an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 18 ring carbon atoms which may be substituted with an alkyl group having 1 to 10 carbon atoms, and an arylalkyl group having 7 to 19 carbon atoms. The alkyl group may be a linear alkyl group or a branched alkyl group. The alkenyl group may be a linear alkenyl group or a branched alkenyl group.

[0035] R ｂ３ The alkyl group, the cycloalkyl group, and the aryl group that can be selected as R ｂ２ Examples of groups that can be selected as R include the same as alkyl groups, cycloalkyl groups, and aryl groups. ｂ３ Examples of the alkenyl group that can be selected as R include ethenyl group (vinyl group), propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, and octadecenyl group (oleyl group). ｂ３ Examples of the arylalkyl group that can be selected as the aryl group include a phenylmethyl group, a phenylethyl group, a naphthylmethyl group, and a naphthylethyl group.

[0036] Among these, R ｂ３ is preferably an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, and more preferably an alkyl group having 1 to 20 carbon atoms. ｂ３ The number of carbon atoms in the alkyl group that can be selected as R is preferably 3 to 20, more preferably 4 to 18, even more preferably 6 to 16, and even more preferably 8 to 14. ｂ３ The alkenyl group that can be selected as above preferably has 2 to 20 carbon atoms, more preferably 3 to 18 carbon atoms, and even more preferably 6 to 16 carbon atoms.

[0037] From the viewpoint of obtaining a lubricating oil composition with improved high-temperature detergency, component (B) used in one embodiment of the present invention preferably contains at least a compound (B1) represented by the general formula (b-1), and more preferably contains at least a compound (B11) represented by the general formula (b-11). In the lubricating oil composition of one embodiment of the present invention, the content of component (B1) or (B11) in component (B) is preferably 40 to 100 mass% or more, more preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, even more preferably 80 to 100 mass%, still more preferably 90 to 100 mass%, and particularly preferably 95 to 100 mass%, based on the total amount (100 mass%) of component (B) contained in the lubricating oil composition, from the viewpoint of obtaining a lubricating oil composition with further improved high-temperature detergency.

[0038] From the above viewpoints, in the lubricating oil composition of one embodiment of the present invention, the content of component (B) is preferably 0.60 mass% or more, more preferably 0.65 mass% or more, more preferably 0.70 mass% or more, more preferably 0.85 mass% or more, more preferably 1.00 mass% or more, even more preferably 1.20 mass% or more, even more preferably 1.40 mass% or more, even more preferably 1.70 mass% or more, even more preferably 2.00 mass% or more, even more preferably 2.10 mass% or more, still more preferably 2.20 mass% or more, still more preferably 2.50 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint of obtaining a lubricating oil composition with even better long drain properties. % by mass or more, particularly preferably 2.55% by mass or more, and from the viewpoint of obtaining a lubricating oil composition that can better maintain high-temperature detergency, it is preferably 10.0% by mass or less, more preferably 9.5% by mass or less, more preferably 9.0% by mass or less, even more preferably 8.5% by mass or less, even more preferably 8.0% by mass or less, still more preferably 7.5% by mass or less, particularly preferably 7.0% by mass or less, and may even be 6.5% by mass or less, 6.0% by mass or less, 5.5% by mass or less, 5.0% by mass or less, 4.5% by mass or less, 4.0% by mass or less, less than 3.5% by mass, 3.4% by mass or less, 3.2% by mass or less, or 3.0% by mass or less, or may be less than 3.0% by mass.

[0039] In the lubricating oil composition of one embodiment of the present invention, the content of component (B) calculated as nitrogen atoms, based on the total amount (100% by mass) of the lubricating oil composition, is preferably 0.020% by mass or more, more preferably more than 0.050% by mass, more preferably 0.055% by mass or more, more preferably 0.060% by mass or more, even more preferably 0.070% by mass or more, even more preferably 0.080% by mass or more, still more preferably 0.090% by mass or more, and particularly preferably 0.100% by mass or more, from the viewpoint of obtaining a lubricating oil composition with superior long drain properties. From the viewpoint of obtaining a lubricating oil composition that can better maintain high-temperature detergency, the content is preferably 0.60 mass % or less, more preferably 0.50 mass % or less, more preferably 0.45 mass % or less, even more preferably 0.42 mass % or less, even more preferably 0.40 mass % or less, still more preferably 0.37 mass % or less, particularly preferably 0.35 mass % or less, and may further be 0.32 mass % or less, 0.30 mass % or less, 0.27 mass % or less, 0.25 mass % or less, 0.22 mass % or less, or 0.20 mass % or less.

[0040] <Component (C): Zinc Organic Dithiophosphate> The lubricating oil composition of one embodiment of the present invention contains, as component (C), an organic zinc dithiophosphate (hereinafter also referred to as "ZnDTP") having at least one primary alkyl group. By containing component (C), it is possible to obtain a lubricating oil composition with improved resistance to copper elution. In one embodiment of the present invention, component (C) may be used alone or in combination of two or more types.

[0041] Component (C) used in one embodiment of the present invention may be ZnDTP having at least one primary alkyl group, or may be ZnDTP having an alkyl group other than a primary alkyl group or a hydrocarbon group other than an alkyl group. However, from the viewpoint of obtaining a lubricating oil composition with improved copper elution resistance, component (C) used in one embodiment of the present invention preferably contains compound (C1) represented by the following general formula (c-1):

[0042] In the above general formula (c-1), R ｃ１ ~R ｃ４ are each independently a primary alkyl group.ｃ１ ~R ｃ４ In view of the above, the content of component (C1) in component (C) used in one embodiment of the present invention is preferably 60 to 100 mass%, more preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 85 to 100 mass%, still more preferably 90 to 100 mass%, and particularly preferably 95 to 100 mass%, based on the total amount (100 mass%) of component (C) contained in the lubricating oil composition.

[0043] R ｃ１ ~R ｃ４ The number of carbon atoms in the primary alkyl group that can be selected as the alkyl group is preferably 1 to 7, more preferably 2 to 7, even more preferably 3 to 7, and still more preferably 4 to 7, from the viewpoint of obtaining a lubricating oil composition with further improved copper elution resistance.

[0044] R ｃ１ ~R ｃ４ Examples of the primary alkyl group that can be selected as the alkyl group include groups represented by the following general formula (ci):

[0045] In the above formula (ci), R ｃ R is a hydrogen atom or an alkyl group, and the alkyl group may be a linear alkyl group or a branched alkyl group. ｃ The number of carbon atoms in the alkyl group that can be selected as R is preferably 1 to 6, more preferably 2 to 6, and even more preferably 3 to 5. ｃ Examples of the alkyl group that can be selected as the alkyl group include a methyl group, an ethyl group, a propyl group (n-propyl group, isopropyl group), a butyl group (n-butyl group, s-butyl group, t-butyl group, isobutyl group), a pentyl group (n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group), a hexyl group (n-hexyl group, 2-methylpentyl group, 3-methylpentyl group, 2,2-dimethylbutyl group, 2,3-dimethylbutyl group), and the like.

[0046] In the lubricating oil composition of one embodiment of the present invention, the content of component (C) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.01 mass% or more, more preferably 0.05 mass% or more, more preferably 0.10 mass% or more, even more preferably 0.30 mass% or more, even more preferably 0.50 mass% or more, still more preferably 0.70 mass% or more, still more preferably 0.80 mass% or more, and particularly preferably 0.90 mass% or more, from the viewpoint of obtaining a lubricating oil composition with improved copper elution resistance; and from the viewpoint of obtaining a lubricating oil composition with good high-temperature detergency, preferably 7.0 mass% or less, more preferably 6.0 mass% or less, more preferably 5.0 mass% or less, even more preferably 4.0 mass% or less, still more preferably 3.0 mass% or less, and particularly preferably 2.0 mass% or less.

[0047] In the lubricating oil composition of one embodiment of the present invention, the content of component (C) in terms of zinc atoms, based on the total amount (100% by mass) of the lubricating oil composition, is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.03% by mass or more, still more preferably 0.05% by mass or more, and particularly preferably 0.07% by mass or more, from the viewpoint of obtaining a lubricating oil composition with further improved copper elution resistance; and is preferably 0.70% by mass or less, more preferably 0.50% by mass or less, even more preferably 0.30% by mass or less, still more preferably 0.20% by mass or less, and particularly preferably 0.15% by mass or less, from the viewpoint of obtaining a lubricating oil composition with good high-temperature detergency.

[0048] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition having further improved high-temperature detergency and further improved copper elution resistance, the content ratio of component (B) to component (C) [(B) / (C)], in mass ratio, is preferably 0.5 or more, more preferably 0.7 or more, more preferably 1.0 or more, even more preferably 1.2 or more, still more preferably 1.5 or more, still more preferably 1.7 or more, still more preferably 2.0 or more, and particularly preferably 2.2 or more, and is also preferably 10.0 or less, more preferably 8.00 or less, more preferably 7.00 or less, more preferably 6.00 or less, even more preferably 5.50 or less, still more preferably 5.00 or less, still more preferably 4.50 or less, still more preferably 4.00 or less, and particularly preferably 3.50 or less.

[0049] <Zinc organic dithiophosphate not corresponding to component (C)> The lubricating oil composition of one embodiment of the present invention may contain an organic zinc dithiophosphate not corresponding to component (C), to the extent that the effects of the present invention are not impaired. The organic zinc dithiophosphate not corresponding to component (C) is ZnDTP that does not have a primary alkyl group, such as ZnDTP in which all of the substituents are secondary alkyl groups.

[0050] However, from the viewpoint of obtaining a lubricating oil composition with better copper elution resistance, the lower the content of zinc organic dithiophosphate that does not fall under component (C), the better, and it is even more preferable that it is substantially free of such zinc organic dithiophosphate. In this specification, the phrase "substantially free of zinc organic dithiophosphate that does not fall under component (C)" stipulates that the zinc organic dithiophosphate is blended and contained for a specific purpose, but does not stipulate that the zinc organic dithiophosphate is unintentionally or unavoidably mixed in or present in the composition.

[0051] In the lubricating oil composition of one embodiment of the present invention, the content of the zinc organic dithiophosphate that does not fall under component (C) is preferably less than 0.001 mass %, more preferably less than 0.0001 mass %, and even more preferably less than 0.00001 mass %, based on the total amount (100 mass %) of the lubricating oil composition.

[0052] In the lubricating oil composition of one embodiment of the present invention, the content of the zinc organic dithiophosphate that does not fall under component (C) is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, more preferably less than 1 part by mass, even more preferably less than 0.1 part by mass, even more preferably less than 0.01 part by mass, still more preferably less than 0.001 part by mass, and particularly preferably less than 0.0001 part by mass, per 100 parts by mass of the total amount of component (C) contained in the lubricating oil composition.

[0053] <Component (D): Molybdenum dithiocarbamate> The lubricating oil composition of one embodiment of the present invention may contain molybdenum dithiocarbamate as component (D). By containing component (D), it is possible to obtain a lubricating oil composition with further improved copper elution resistance. In one embodiment of the present invention, component (D) may be used alone or in combination of two or more types.

[0054] Examples of component (D) used in one embodiment of the present invention include a dinuclear molybdenum dithiocarbamate containing two molybdenum atoms per molecule and a trinuclear molybdenum dithiocarbamate containing three molybdenum atoms per molecule, with a dinuclear molybdenum dithiocarbamate being preferred. Component (D) used in one embodiment of the present invention preferably includes one or more compounds selected from compound (D1) represented by general formula (d-1) below and compound (D2) represented by general formula (d-2) below:

[0055]

[0056] In the above general formulas (d-1) and (d-2), R ｄ１ ~R ｄ４ each independently represents a hydrocarbon group, and may be the same as or different from each other. １ ~X ８ each independently represents an oxygen atom or a sulfur atom, and may be the same as or different from each other. １ ~X ８ In one embodiment of the present invention, at least one of X in formula (d-1) is a sulfur atom. １ and X ２ is an oxygen atom, and X ３ ~X８ is preferably a sulfur atom. １ ~X ４ is preferably an oxygen atom.

[0057] In the above general formula (d-1), from the viewpoint of improving solubility, X １ ~X ８ The molar ratio of sulfur atoms to oxygen atoms [sulfur atoms / oxygen atoms] in the alkylene oxide is preferably 1 / 4 to 4 / 1, more preferably 1 / 3 to 3 / 1.

[0058] In the above general formulas (d-1) and (d-2), R ｄ１ ~R ｄ４ Examples of the hydrocarbon group that can be selected include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, isooctyl, nonyl, decyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl; alkenyl groups such as octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, and pentadecenyl; cyclohexyl, dimethylcyclohexyl, and dimethylcyclohexyl; cycloalkyl groups such as cyclohexyl, ethylcyclohexyl, methylcyclohexylmethyl, cyclohexylethyl, propylcyclohexyl, butylcyclohexyl, and heptylcyclohexyl groups; aryl groups such as phenyl, naphthyl, anthracenyl, biphenyl, and terphenyl groups; alkylaryl groups such as tolyl, dimethylphenyl, butylphenyl, nonylphenyl, methylbenzyl, and dimethylnaphthyl groups; and arylalkyl groups such as phenylmethyl, phenylethyl, and diphenylmethyl groups. ｄ１ ~R ｄ４ The hydrocarbon group that can be selected as is preferably an alkyl group or an alkenyl group, more preferably an alkyl group.

[0059] R ｄ１ ~R ｄ４The number of carbon atoms in the hydrocarbon group that can be selected as above is preferably 1 to 20, more preferably 3 to 18, even more preferably 5 to 16, still more preferably 8 to 14, and particularly preferably 8 or 13, from the viewpoint of obtaining a lubricating oil composition with further improved copper elution resistance.

[0060] From the viewpoint of obtaining a lubricating oil composition with improved resistance to copper elution, R in the above general formulas (d-1) and (d-2) used as component (D) in one embodiment of the present invention is ｄ１ ~R ｄ４ In the compound in which is an alkyl group, the molar ratio of the alkyl group (α) having 10 or less carbon atoms (preferably 3 to 10, more preferably 5 to 10, and even more preferably 7 to 10) to the alkyl group (β) having 11 or more carbon atoms (preferably 11 to 20, more preferably 11 to 16, and even more preferably 12 to 14) [(α) / (β)] is preferably 1 / 7 to 7 / 1, more preferably 1 / 6 to 6 / 1, more preferably 1 / 5 to 5 / 1, even more preferably 1 / 4 to 4 / 1, still more preferably 1 / 3 to 3 / 1, and particularly preferably 1 / 2 to 2 / 1.

[0061] In the lubricating oil composition of one embodiment of the present invention, the content of component (D) is, from the viewpoint of obtaining a lubricating oil composition with further improved copper elution resistance, preferably 0.05% by mass or more, more preferably 0.10% by mass or more, even more preferably 0.20% by mass or more, still more preferably 0.30% by mass or more, and particularly preferably 0.50% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition, and may also be 5.0% by mass or less, 4.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less.

[0062] In the lubricating oil composition of one embodiment of the present invention, the content of component (D) in terms of molybdenum atoms, based on the total amount (100 mass%) of the lubricating oil composition, is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, even more preferably 0.03 mass% or more, still more preferably 0.04 mass% or more, and particularly preferably 0.05 mass% or more, from the viewpoint of obtaining a lubricating oil composition with further improved copper elution resistance, and may also be 0.70 mass% or less, 0.50 mass% or less, 0.30 mass% or less, 0.20 mass% or less, or 0.10 mass% or less.

[0063] <Molybdenum dithiophosphate> The lubricating oil composition of one embodiment of the present invention may contain molybdenum dithiophosphate within a range that does not impair the effects of the present invention. Examples of molybdenum dithiophosphate include compounds represented by the following general formula (d'-i) and compounds represented by the following general formula (d'-ii):

[0064] In the above general formulas (d'-i) and (d'-ii), R ｄ１１ ~R ｄ１４ each independently represents a hydrocarbon group, and may be the same as or different from each other. １１ ~X １８ each independently represents an oxygen atom or a sulfur atom, and may be the same as or different from each other. １１ ~X １８ At least two of the groups are sulfur atoms.

[0065] From the viewpoint of obtaining a lubricating oil composition with improved copper elution resistance, the lower the content of molybdenum dithiophosphate, the more preferable, and it is even more preferable that it is substantially free of molybdenum dithiophosphate. In this specification, the phrase "substantially free of molybdenum dithiophosphate" denies embodiments in which the molybdenum dithiophosphate is blended and contained for a specific purpose, but does not negate embodiments in which the molybdenum dithiophosphate is unintentionally or unavoidably mixed in or present.

[0066] In the lubricating oil composition of one embodiment of the present invention, the content of molybdenum dithiophosphate is preferably less than 0.001 mass %, more preferably less than 0.0001 mass %, and even more preferably less than 0.00001 mass %, based on the total amount (100 mass %) of the lubricating oil composition.

[0067] In the lubricating oil composition of one embodiment of the present invention, the content of molybdenum dithiophosphate is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, more preferably less than 1 part by mass, even more preferably less than 0.1 part by mass, even more preferably less than 0.01 part by mass, still more preferably less than 0.001 part by mass, and particularly preferably less than 0.0001 part by mass, per 100 parts by mass of the total amount of component (C) contained in the lubricating oil composition.

[0068] <Component (E): Antioxidant not corresponding to component (B)> From the viewpoint of obtaining a lubricating oil composition with further improved high-temperature detergency, the lubricating oil composition of one embodiment of the present invention may contain, as component (E), an antioxidant not corresponding to component (B). Examples of component (E) used in one embodiment of the present invention include amine-based antioxidants other than hindered amine compounds, phenol-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. In one embodiment of the present invention, component (E) may be used alone or in combination of two or more types.

[0069] Component (E) used in one embodiment of the present invention preferably contains one or more selected from the group consisting of an amine-based antioxidant (E1) and a phenol-based antioxidant (E2) that do not fall under component (B), and more preferably contains both component (E1) and component (E2).

[0070] The total content of components (E1) and (E2) in component (E) used in one embodiment of the present invention is preferably 60 to 100 mass%, more preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 85 to 100 mass%, still more preferably 90 to 100 mass%, and particularly preferably 95 to 100 mass%, based on the total amount (100 mass%) of component (E) contained in the lubricating oil composition.

[0071] When component (E) used in one embodiment of the present invention contains both components (E1) and (E2), the content ratio of component (E1) to component (E2) [(E1) / (E2)], expressed by mass, is preferably 0.10 to 5.0, more preferably 0.30 to 4.5, more preferably 0.50 to 4.0, even more preferably 0.75 to 3.5, still more preferably 1.0 to 3.0, and particularly preferably 1.2 to 2.7.

[0072] Examples of the component (E1) used in one embodiment of the present invention include diphenylamine-based antioxidants such as diphenylamine and alkylated diphenylamines having an alkyl group containing 3 to 20 carbon atoms (preferably 6 to 16, and more preferably 8 to 12 carbon atoms); and naphthylamine-based antioxidants such as α-naphthylamine, phenyl-α-naphthylamine, and substituted phenyl-α-naphthylamines having an alkyl group containing 3 to 20 carbon atoms (preferably 6 to 16, and more preferably 8 to 12 carbon atoms).

[0073] Examples of component (E2) used in one embodiment of the present invention include monophenol-based antioxidants such as 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and benzenepropanoic acid-3,5-bis(1,1-dimethylethyl)-4-hydroxyalkyl ester; and diphenol-based antioxidants such as 4,4'-methylenebis(2,6-di-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), and thiodiethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate].

[0074] In the lubricating oil composition of one embodiment of the present invention, the content of component (E) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.01 mass% or more, more preferably 0.05 mass% or more, more preferably 0.10 mass% or more, even more preferably 0.30 mass% or more, even more preferably 0.50 mass% or more, still more preferably 0.70 mass% or more, and particularly preferably 1.00 mass% or more, and may also be 10.0 mass% or less, 8.0 mass% or less, 6.0 mass% or less, 5.0 mass% or less, 4.0 mass% or less, 3.0 mass% or less, or 2.0 mass% or less.

[0075] In the lubricating oil composition of one embodiment of the present invention, the ratio of component (E) to component (B) [(E) / (B)], expressed by mass, is preferably 0.10 or more, more preferably 0.20 or more, even more preferably 0.30 or more, still more preferably 0.40 or more, and particularly preferably 0.45 or more; and is preferably 6.0 or less, more preferably 5.0 or less, even more preferably 4.0 or less, still more preferably 3.0 or less, and particularly preferably 2.0 or less.

[0076] In the lubricating oil composition of one embodiment of the present invention, the content of component (E1) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.01 mass% or more, more preferably 0.05 mass% or more, more preferably 0.10 mass% or more, even more preferably 0.20 mass% or more, even more preferably 0.30 mass% or more, still more preferably 0.50 mass% or more, and particularly preferably 0.70 mass% or more, and may also be 5.0 mass% or less, 4.0 mass% or less, 3.0 mass% or less, 2.0 mass% or less, or 1.5 mass% or less.

[0077] In the lubricating oil composition of one embodiment of the present invention, the ratio of component (E1) to component (B) [(E1) / (B)], expressed by mass, is preferably 0.05 or more, more preferably 0.10 or more, even more preferably 0.20 or more, still more preferably 0.25 or more, and particularly preferably 0.30 or more; and is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, still more preferably 2.0 or less, and particularly preferably 1.0 or less.

[0078] In the lubricating oil composition of one embodiment of the present invention, the content of component (E2) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.01 mass% or more, more preferably 0.05 mass% or more, more preferably 0.10 mass% or more, even more preferably 0.20 mass% or more, still more preferably 0.30 mass% or more, and particularly preferably 0.40 mass% or more, and may also be 5.0 mass% or less, 4.0 mass% or less, 3.0 mass% or less, 2.0 mass% or less, or 1.0 mass% or less.

[0079] In the lubricating oil composition of one embodiment of the present invention, the ratio of component (E2) to component (B) [(E2) / (B)], expressed by mass, is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.10 or more, still more preferably 0.12 or more, and particularly preferably 0.15 or more; and is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.0 or less, still more preferably 0.70 or less, and particularly preferably 0.50 or less.

[0080] <Component (F): Imide-Based Compound> The lubricating oil composition of one embodiment of the present invention may contain an imide-based compound as component (F). By containing component (F), it is possible to obtain a lubricating oil composition that can suppress sludge deposition. In one embodiment of the present invention, component (F) may be used alone or in combination of two or more types.

[0081] In this specification, the term "imide-based compound" means a compound having an imide structure represented by the following formula (f-0), and also includes a chain compound having the imide structure and a cyclic compound having the imide structure. (In the above formula, * indicates the bond position.)

[0082] Component (F) used in one embodiment of the present invention may be a modified imide-based compound reacted with one or more compounds selected from the group consisting of boron compounds, alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, and organic acids, or may be a non-modified imide-based compound.

[0083] Component (F) used in one embodiment of the present invention preferably contains one or more selected from alkenyl succinimides and modified products thereof, more preferably contains one or more selected from non-boron-modified alkenyl succinimides (F1) and boron-modified alkenyl succinimides (F2), and even more preferably contains both components (F1) and (F2).

[0084] The total content of components (F1) and (F2) in component (F) used in one embodiment of the present invention is preferably 60 to 100 mass%, more preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 85 to 100 mass%, still more preferably 90 to 100 mass%, and particularly preferably 95 to 100 mass%, based on the total amount (100 mass%) of component (F) contained in the lubricating oil composition.

[0085] The non-boron-modified alkenyl succinimide (F1) is preferably at least one selected from the group consisting of alkenyl succinic acid bisimides (F11) represented by the following general formula (f-1) and alkenyl succinic acid monoimides (F12) represented by the following general formula (f-2):

[0086] In the above general formulas (f-1) and (f-2), R ｆ１ , R ｆ２ and R ｆ３ are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 3000 (preferably 900 to 2500). ｆ１ , R ｆ２ and R ｆ３ Examples of the alkenyl group that can be selected as A include a polybutenyl group, a polyisobutenyl group, an ethylene-propylene copolymer, and the like. Among these, a polybutenyl group or a polyisobutenyl group is preferred. ｆ１ , A ｆ２ and A ｆ３ are each independently an alkylene group having 2 to 5 carbon atoms. z1 is an integer of 0 to 10, preferably an integer of 1 to 4, and more preferably 2 or 3. z2 is an integer of 1 to 10, preferably an integer of 2 to 5, and more preferably 3 or 4.

[0087] Examples of the boron-modified alkenyl succinimide (F2) used in one embodiment of the present invention include a boron-modified alkenyl succinic acid bisimide represented by the general formula (f-1) above and a boron-modified alkenyl succinic acid monoimide represented by the following general formula (f-2):

[0088] In one embodiment of the present invention, the ratio of boron atoms to nitrogen atoms [B / N] constituting component (F2) is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, still more preferably 0.5 or more, and particularly preferably 0.7 or more.

[0089] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of high-temperature detergency, the content ratio of component (F1) to component (F2) [(F1) / (F2)], expressed as a mass ratio, is preferably 0.10 or more, more preferably 0.50 or more, even more preferably 0.70 or more, still more preferably 1.00 or more, and particularly preferably 1.20 or more, and is also preferably less than 5.00, more preferably less than 4.00, even more preferably less than 3.00, still more preferably less than 2.50, and particularly preferably less than 2.00.

[0090] In the lubricating oil composition of one embodiment of the present invention, the ratio of the content of boron atoms derived from component (F2) to the content of nitrogen atoms derived from component (F) [B / N], expressed by mass, is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.10 or more, still more preferably 0.20 or more, and particularly preferably 0.30 or more, and is preferably 0.90 or less, more preferably 0.80 or less, even more preferably 0.70 or less, still more preferably 0.60 or less, and particularly preferably 0.55 or less.

[0091] In the lubricating oil composition of one embodiment of the present invention, the content of component (F) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.50 mass% or more, more preferably 1.0 mass% or more, even more preferably 2.0 mass% or more, still more preferably 3.0 mass% or more, particularly preferably 4.0 mass% or more, and is preferably 12.0 mass% or less, more preferably 10.0 mass% or less, even more preferably 9.0 mass% or less, still more preferably 8.5 mass% or less, particularly preferably 8.0 mass% or less.

[0092] In the lubricating oil composition of one embodiment of the present invention, the content of component (F) calculated as nitrogen atoms is preferably 0.010 to 0.200 mass%, more preferably 0.020 to 0.170 mass%, even more preferably 0.030 to 0.130 mass%, still more preferably 0.040 to 0.100 mass%, and particularly preferably 0.050 to 0.090 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0093] In the lubricating oil composition of one embodiment of the present invention, the content of component (F1) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.10 mass% or more, more preferably 0.50 mass% or more, even more preferably 1.0 mass% or more, still more preferably 1.5 mass% or more, particularly preferably 2.0 mass% or more, and is preferably 10.0 mass% or less, more preferably 8.0 mass% or less, even more preferably 7.0 mass% or less, still more preferably 6.5 mass% or less, particularly preferably 6.0 mass% or less.

[0094] In the lubricating oil composition of one embodiment of the present invention, the content of component (F1) calculated as nitrogen atoms is preferably 0.005 to 0.150 mass%, more preferably 0.010 to 0.120 mass%, even more preferably 0.015 to 0.100 mass%, still more preferably 0.020 to 0.080 mass%, and particularly preferably 0.025 to 0.070 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0095] In the lubricating oil composition of one embodiment of the present invention, the content of component (F2) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.10 mass% or more, more preferably 0.30 mass% or more, even more preferably 0.50 mass% or more, still more preferably 1.0 mass% or more, particularly preferably 1.5 mass% or more, and is preferably 8.0 mass% or less, more preferably 7.0 mass% or less, even more preferably 6.0 mass% or less, still more preferably 5.0 mass% or less, particularly preferably 4.0 mass% or less.

[0096] In the lubricating oil composition of one embodiment of the present invention, the content of component (F2) calculated as boron atoms is preferably 0.001 to 0.100 mass%, more preferably 0.005 to 0.090 mass%, even more preferably 0.010 to 0.080 mass%, still more preferably 0.015 to 0.070 mass%, and particularly preferably 0.020 to 0.060 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0097] <Component (G): Metallic Detergent> The lubricating oil composition of one embodiment of the present invention may contain a metallic detergent as component (G). By containing component (G), a lubricating oil composition with better high-temperature detergency can be obtained. In one embodiment of the present invention, component (G) may be used alone or in combination of two or more types.

[0098] Component (G) used in one embodiment of the present invention includes metal salts such as metal sulfonates, metal salicylates, and metal phenates. The metal atoms constituting the metal salts are preferably selected from alkali metals and alkaline earth metals, more preferably sodium, calcium, magnesium, or barium, and even more preferably calcium.

[0099] Component (G) used in one embodiment of the present invention preferably contains one or more selected from calcium sulfonate, calcium salicylate, and calcium phenate, and more preferably contains calcium salicylate. The calcium salicylate content is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, and even more preferably 80 to 100 mass%, based on the total amount (100 mass%) of metallic detergents contained in the lubricating oil composition.

[0100] The base number of the metallic detergent is preferably 0 to 600 mgKOH / g. Note that, component (G) used in one embodiment of the present invention may be a neutral metallic detergent or an overbased metallic detergent. Note that, a neutral metallic detergent means a metallic detergent having a base number of 0 to 100 mgKOH / g or more, whereas an overbased metallic detergent means a metallic detergent having a base number of more than 100 mgKOH / g.

[0101] In the lubricating oil composition of one embodiment of the present invention, the content of component (G) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 0.10 mass% or more, more preferably 0.30 mass% or more, more preferably 0.50 mass% or more, more preferably 0.70 mass% or more, even more preferably 1.00 mass% or more, even more preferably 1.20 mass% or more, even more preferably 1.50 mass% or more, still more preferably 1.70 mass% or more, particularly preferably 1.90 mass% or more, and is preferably 10.0 mass% or less, more preferably 8.0 mass% or less, more preferably 7.0 mass% or less, even more preferably 6.0 mass% or less, still more preferably 5.0 mass% or less, and particularly preferably 4.0 mass% or less.

[0102] In the lubricating oil composition of one embodiment of the present invention, the content of component (G) in terms of calcium atoms, based on the total amount (100 mass%) of the lubricating oil composition, is preferably at least 50 ppm by mass, more preferably at least 100 ppm by mass, more preferably at least 150 ppm by mass, more preferably at least 200 ppm by mass, even more preferably at least 250 ppm by mass, even more preferably at least 300 ppm by mass, even more preferably at least 350 ppm by mass, still more preferably at least 400 ppm by mass, particularly preferably at least 450 ppm by mass; and is preferably at most 3000 ppm by mass, more preferably at most 2500 ppm by mass, more preferably at most 2000 ppm by mass, even more preferably at most 1500 ppm by mass, still more preferably at most 1000 ppm by mass, particularly preferably at most 800 ppm by mass.

[0103] <Lubricating Oil Additives> The lubricating oil composition of one embodiment of the present invention may further contain lubricating oil additives other than components (B) to (G), as necessary, to the extent that the effects of the present invention are not impaired. Examples of such lubricating oil additives include pour point depressants, viscosity index improvers, friction modifiers, anti-wear agents, extreme pressure agents, metal deactivators, oiliness agents, rust inhibitors, and anti-foaming agents. These lubricating oil additives may be used alone or in combination of two or more.

[0104] The content of each of these lubricating oil additives can be adjusted as appropriate within a range that does not impair the effects of the present invention, but is typically 0.001 to 15 mass %, preferably 0.005 to 10 mass %, and more preferably 0.01 to 5 mass %, for each additive independently, based on the total amount (100 mass %) of the lubricating oil composition.

[0105] [Pour Point Depressant] The lubricating oil composition of one embodiment of the present invention may further contain a pour point depressant. The pour point depressants may be used alone or in combination of two or more. Examples of pour point depressants used in one embodiment of the present invention include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffins and naphthalene, condensates of chlorinated paraffins and phenols, polymethacrylates, polyalkylstyrenes, etc. The weight average molecular weight (Mw) of the pour point depressant used in one embodiment of the present invention may be 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, 20,000 or more, 25,000 or more, 30,000 or more, 35,000 or more, 40,000 or more, 45,000 or more, 50,000 or more, 55,000 or more, or 60,000 or more, and may be 150,000 or less, 120,000 or less, 100,000 or less, 90,000 or less, or 80,000 or less.

[0106] [Viscosity Index Improver] The lubricating oil composition of one embodiment of the present invention may further contain a viscosity index improver. The viscosity index improver may be used alone or in combination of two or more types. Examples of viscosity index improvers used in one embodiment of the present invention include polymers such as non-dispersant polymethacrylate, dispersant polymethacrylate, olefin copolymers (e.g., ethylene-propylene copolymers, etc.), dispersant olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers, etc.). The weight average molecular weight (Mw) of the viscosity index improver used in one embodiment of the present invention may be 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, or 20,000 or more, or may be 1,000,000 or less, 700,000 or less, 500,000 or less, 300,000 or less, 200,000 or less, 100,000 or less, or 50,000 or less.

[0107] [Friction modifiers and anti-wear agents] The lubricating oil composition of one embodiment of the present invention may further contain a friction modifier or anti-wear agent. The friction modifiers or anti-wear agents may be used alone or in combination of two or more. Examples of the friction modifiers and anti-wear agents used in one embodiment of the present invention include sulfur-based compounds such as sulfurized olefins, dialkyl polysulfides, diaryl alkyl polysulfides, and diaryl polysulfides; phosphorus-based compounds such as phosphate esters, thiophosphate esters, phosphites, alkyl hydrogen phosphites, phosphate ester amine salts, and phosphites ester amine salts; ashless friction modifiers such as fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea-based compounds, and hydrazide-based compounds.

[0108] [Extreme Pressure Agent] The lubricating oil composition of one embodiment of the present invention may further contain an extreme pressure agent. The extreme pressure agent may be used alone or in combination of two or more. Examples of the extreme pressure agent used in one embodiment of the present invention include sulfur-based compounds such as sulfurized olefins, dialkyl polysulfides, diaryl alkyl polysulfides, and diaryl polysulfides, and phosphorus-based compounds such as phosphate esters, thiophosphate esters, phosphite esters, alkyl hydrogen phosphites, phosphate ester amine salts, and phosphite ester amine salts.

[0109] [Metal Deactivator] The lubricating oil composition of one embodiment of the present invention may further contain a metal deactivator. The metal deactivators may be used alone or in combination of two or more. Examples of the metal deactivator used in one embodiment of the present invention include benzotriazole, triazole derivatives, benzotriazole derivatives, and thiadiazole derivatives.

[0110] [Oilability Agent] The lubricating oil composition of one embodiment of the present invention may further contain an oiliness agent. The oiliness agent may be used alone or in combination of two or more types. Examples of oiliness agents used in one embodiment of the present invention include saturated and unsaturated aliphatic monocarboxylic acids such as stearic acid and oleic acid, polymerized fatty acids such as dimer acid and hydrogenated dimer acid, hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid, saturated and unsaturated aliphatic monoalcohols such as lauryl alcohol and oleyl alcohol, saturated and unsaturated aliphatic monoamines such as stearylamine and oleylamine, and saturated and unsaturated aliphatic monocarboxylic acid amides such as lauric acid amide and oleic acid amide.

[0111] [Rust inhibitor] The lubricating oil composition of one embodiment of the present invention may further contain a rust inhibitor. The rust inhibitor may be used alone or in combination of two or more. Examples of the rust inhibitor used in one embodiment of the present invention include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, and alkyl polyoxyethylene ethers.

[0112] [Antifoaming Agent] The lubricating oil composition of one embodiment of the present invention may further contain an antifoaming agent. The antifoaming agent may be used alone or in combination of two or more. Examples of the antifoaming agent used in one embodiment of the present invention include alkylsilicone-based antifoaming agents, fluorosilicone-based antifoaming agents, and fluoroalkyl ether-based antifoaming agents.

[0113] <Method for producing lubricating oil composition> There are no particular limitations on the method for producing the lubricating oil composition of one embodiment of the present invention, but from the viewpoint of productivity, it is preferred that the method comprises a step of blending the above-mentioned components (B) and (C) into base oil (A), as well as components (D) to (G) and other lubricating oil additives, as necessary.

[0114] [Properties of Lubricating Oil Composition] The kinematic viscosity of the lubricating oil composition of one embodiment of the present invention at 40°C is preferably 10 to 120 mm ２ / s, more preferably 15 to 100 mm ２ / s, more preferably 20 to 80 mm ２ / s, and even more preferably 25 to 70 mm ２ / s, particularly preferably 27 to 60 mm ２ / s.

[0115] The kinematic viscosity at 100°C of the lubricating oil composition of one embodiment of the present invention is preferably 2.5 to 20.0 mm ２ / s, more preferably 4.0 to 18.0 mm ２ / s, more preferably 5.0 to 15.0 mm ２ / s, and even more preferably 6.0 to 12.0 mm ２ / s, particularly preferably 7.0 to 10.0 mm ２ / s.

[0116] The viscosity index of the lubricating oil composition of one embodiment of the present invention is preferably 80 or more, more preferably 100 or more, more preferably 120 or more, even more preferably 150 or more, still more preferably 170 or more, and particularly preferably 200 or more.

[0117] In the lubricating oil composition of one embodiment of the present invention, the calcium atom content is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 50 ppm by mass or more, more preferably 100 ppm by mass or more, more preferably 150 ppm by mass or more, more preferably 200 ppm by mass or more, even more preferably 250 ppm by mass or more, even more preferably 300 ppm by mass or more, even more preferably 350 ppm by mass or more, still more preferably 400 ppm by mass or more, particularly preferably 450 ppm by mass or more; and is preferably 3000 ppm by mass or less, more preferably 2500 ppm by mass or less, more preferably 2000 ppm by mass or less, even more preferably 1500 ppm by mass or less, still more preferably 1000 ppm by mass or less, particularly preferably 800 ppm by mass or less.

[0118] In the lubricating oil composition of one embodiment of the present invention, the content of zinc atoms is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 50 ppm by mass or more, more preferably 100 ppm by mass or more, even more preferably 300 ppm by mass or more, still more preferably 500 ppm by mass or more, particularly preferably 700 ppm by mass or more, and is preferably 7000 ppm by mass or less, more preferably 5000 ppm by mass or less, even more preferably 3000 ppm by mass or less, still more preferably 2000 ppm by mass or less, particularly preferably 1500 ppm by mass or less.

[0119] In the lubricating oil composition of one embodiment of the present invention, the content of molybdenum atoms is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 100 ppm by mass or more, more preferably 200 ppm by mass or more, even more preferably 300 ppm by mass or more, still more preferably 400 ppm by mass or more, particularly preferably 500 ppm by mass or more, and is preferably 7000 ppm by mass or less, more preferably 5000 ppm by mass or less, even more preferably 3000 ppm by mass or less, still more preferably 2000 ppm by mass or less, particularly preferably 1000 ppm by mass or less.

[0120] In the lubricating oil composition of one embodiment of the present invention, the phosphorus atom content, based on the total amount (100 mass%) of the lubricating oil composition, is preferably at least 50 ppm by mass, more preferably at least 100 ppm by mass, even more preferably at least 200 ppm by mass, still more preferably at least 300 ppm by mass, and particularly preferably at least 400 ppm by mass; and is preferably at most 1000 ppm by mass, more preferably at most 950 ppm by mass, even more preferably at most 900 ppm by mass, still more preferably at most 850 ppm by mass, and particularly preferably at most 750 ppm by mass.

[0121] In the lubricating oil composition of one embodiment of the present invention, the content of boron atoms is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 10 ppm by mass or more, more preferably 50 ppm by mass or more, even more preferably 100 ppm by mass or more, still more preferably 150 ppm by mass or more, and particularly preferably 200 ppm by mass or more; and is preferably 1000 ppm by mass or less, more preferably 900 ppm by mass or less, even more preferably 800 ppm by mass or less, still more preferably 700 ppm by mass or less, and particularly preferably 600 ppm by mass or less.

[0122] In the lubricating oil composition of one embodiment of the present invention, the nitrogen atom content, based on the total amount (100 mass%) of the lubricating oil composition, is preferably 100 ppm by mass or more, more preferably 500 ppm by mass or more, even more preferably 1000 ppm by mass or more, still more preferably 1500 ppm by mass or more, particularly preferably 1800 ppm by mass or more, and is preferably 8000 ppm by mass or less, more preferably 6000 ppm by mass or less, even more preferably 5000 ppm by mass or less, still more preferably 4000 ppm by mass or less, particularly preferably 3000 ppm by mass or less.

[0123] The amount of copper elution measured in a copper elution resistance test described in the Examples below for a lubricating oil composition according to one embodiment of the present invention is preferably less than 250 ppm by mass, more preferably less than 220 ppm by mass, more preferably less than 200 ppm by mass, even more preferably less than 185 ppm by mass, even more preferably less than 170 ppm by mass, still more preferably less than 120 ppm by mass, and particularly preferably less than 100 ppm by mass.

[0124] The lubricating oil composition of one embodiment of the present invention is subjected to a hot tube test described in the Examples below to evaluate the degree of discoloration, and the merit score is preferably 7.0 or more, more preferably 7.5 or more, even more preferably 8.0 or more, still more preferably 8.5 or more, and particularly preferably 9.0 or more.

[0125] [Uses of the lubricating oil composition] The lubricating oil composition of one embodiment of the present invention has excellent copper elution resistance and can maintain good long-drain properties for a long period of time. Therefore, the lubricating oil composition of one embodiment of the present invention can be applied to various devices that can exhibit the above properties, and can be suitably used for lubricating the components in an internal combustion engine, and in particular, can be suitably used for lubricating the components in an internal combustion engine of a hybrid system having an internal combustion engine and an electric motor as a power source.

[0126] Furthermore, in consideration of the above-described properties of the lubricating oil composition of one embodiment of the present invention, the present invention can also provide the following [I] and [II]: [I] An internal combustion engine mounted on a hybrid system, filled with the lubricating oil composition of one embodiment of the present invention described above. [II] A method for lubricating an internal combustion engine, in which the lubricating oil composition of one embodiment of the present invention described above is applied to an internal combustion engine mounted on a hybrid system.

[0127] The hybrid systems described in [I] and [II] above are mechanisms having an internal combustion engine and an electric motor as power sources. Examples of the hybrid systems described in [I] and [II] above include hybrid automobiles, hybrid motorcycles, hybrid trains, and hybrid ships. The internal combustion engine described in [I] above is filled with the lubricating oil composition of one embodiment of the present invention described above, and is a device installed in the hybrid system together with an electric motor, which is an electric motor. Furthermore, the method for lubricating an internal combustion engine described in [II] above specifies that the lubricating oil composition of one embodiment of the present invention is applied to the internal combustion engine installed in the hybrid system, but the lubricating oil composition may also be applied to an electric motor, which is an electric motor.

[0128] As described above, the present invention discloses the following aspects: [1] A lubricating oil composition containing a base oil (A), a hindered amine compound (B), and an organic zinc dithiophosphate (C) having at least one primary alkyl group. [2] The lubricating oil composition according to the above item [1], wherein component (C) includes a compound (C1) represented by the following general formula (c-1): [In the above formula, R ｃ１ ~R ｃ４are each independently a primary alkyl group.] [3] The lubricating oil composition according to [2] above, wherein the primary alkyl group has 1 to 7 carbon atoms. [4] The lubricating oil composition according to any one of [1] to [3] above, wherein the content of component (C) is 0.01 to 7.0 mass% based on the total amount of the lubricating oil composition. [5] The lubricating oil composition according to any one of [1] to [4] above, wherein the content of component (B) is 0.60 to 10.0 mass% based on the total amount of the lubricating oil composition. [6] The lubricating oil composition according to any one of [1] to [5] above, wherein the content ratio of component (B) to component (C) [(B) / (C)] is 0.5 to 10.0 by mass. [7] The lubricating oil composition according to any one of the above [1] to [6], wherein component (B) comprises one or more compounds selected from the group consisting of a compound (B1) represented by the following general formula (b-1) and a compound (B2) represented by the following general formula (b-2): [In the above formula, R ｂ１ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. ｂ２ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an aryl group having 6 to 18 ring carbon atoms, a hydroxyl group, an amino group, or —O—CO—R ｂ３ A group represented by R ｂ３ is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. Z is an alkylene group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 18 ring carbon atoms, an arylene group having 6 to 18 ring carbon atoms, an oxygen atom, a sulfur atom, or —O—CO—(CH ２ ) ｎ-CO-O- (where n is an integer of 1 to 20).] [8] The lubricating oil composition according to any one of the above [1] to [7], further comprising molybdenum dithiocarbamate (D). [9] The lubricating oil composition according to any one of the above [1] to [8], further comprising an antioxidant (E) that does not fall under the category of component (B), wherein component (E) comprises one or more selected from an amine-based antioxidant (E1) and a phenol-based antioxidant (E2) that do not fall under the category of component (B).

[10] The lubricating oil composition according to any one of the above [1] to [9], further comprising an imide compound (F), wherein component (F) comprises one or more selected from a non-boron-modified alkenyl succinimide (F1) and a boron-modified alkenyl succinimide (F2).

[11] The lubricating oil composition according to the above

[10] , wherein component (F) comprises component (F1) and component (F2), and the content ratio of component (F1) to component (F2) [(F1) / (F2)] is less than 5.00 by mass.

[12] The lubricating oil composition according to any one of the above [1] to

[11] , which is used for lubricating an internal combustion engine of a hybrid system.

[13] An internal combustion engine mounted in a hybrid system, which is filled with the lubricating oil composition according to any one of the above [1] to

[12] .

[14] A method for lubricating an internal combustion engine mounted in a hybrid system, in which the lubricating oil composition according to any one of the above [1] to

[12] is applied to an internal combustion engine mounted in a hybrid system.

[0129] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are as follows.

[0130] (1) Content of calcium atom (Ca), zinc atom (Zn), molybdenum atom (Mo), phosphorus atom (P), and boron atom (B): Measured in accordance with JPI-5S-38-92. (2) Content of nitrogen atom (N): Measured in accordance with JIS K2609:1998.

[0131] (3) Weight-average molecular weight (Mw) Measurement was performed using a gel permeation chromatograph (Agilent Technologies, "1260 HPLC") under the following conditions, and the value measured in terms of standard polystyrene was used. (Measurement conditions) Column: Two "Shodex LF404" columns connected in series. Column temperature: 35°C. Developing solvent: chloroform. Flow rate: 0.3 mL / min.

[0132] Lubricating oil compositions were prepared by adding and mixing the base oil and various additives in the amounts shown in Table 1. Details of the components used in preparing the lubricating oil compositions are as follows:

[0133] <Component (A): Base Oil> "100N mineral oil": paraffinic mineral oil classified in Group III of the API base oil category, kinematic viscosity at 40°C = 20 mm ２ / s, viscosity index = 122, corresponds to component (A). <Component (B): Hindered amine compound> "Hindered amine compound": 2,2,6,6-tetramethylpiperidin-4-yl dodecanoate, in the general formula (b-11), R ｂ１ = hydrogen atom, R ｂ３ =-C １１ H ２３ The nitrogen atom content is 4.13% by mass, and the compound corresponds to component (B11). <Component (C): ZnDTP> "Primary zinc dialkyldithiophosphate": a compound represented by the formula (c-1) above, ｃ１ ~R ｃ４ are all primary alkyl groups having 6 carbon atoms, the phosphorus atom content is 7.5% by mass, the zinc atom content is 8.5% by mass, and this corresponds to component (C). <ZnDTP not corresponding to component (C)> "Secondary zinc dialkyldithiophosphate": a compound in which R ｃ１ ~R ｃ４ are all secondary alkyl groups. Phosphorus atom content = 7.1 mass %, zinc atom content = 8.2 mass %. <Component (D): Molybdenum dithiocarbamate> "Molybdenum dithiocarbamate (1)": a compound represented by the general formula (d-2) above, ｄ１ ~R ｄ４are all alkyl groups having 8 or 13 carbon atoms (alkyl group having 8 carbon atoms (α) / alkyl group having 13 carbon atoms (β)=1 / 1 (molar ratio)), which corresponds to component (D2). ｄ１ ~R ｄ４ are all alkyl groups having 14 carbon atoms, and corresponds to component (D2). <Component (E): Antioxidant not corresponding to component (B)> - "Amine-based antioxidant not corresponding to component (B)": Dinonyldiphenylamine, nitrogen atom content = 3.6 mass%, corresponds to component (E1). - "Phenol-based antioxidant": Benzenepropanoic acid 3,5-bis(1,1-dimethylethyl)-4-hydroxyalkyl ester, corresponds to component (E2). <Component (F): Imide-based compound> - "Non-boron-modified alkenyl succinimide": Polybutenyl succinic acid bisimide, nitrogen atom (N) content = 1.0 mass%, corresponds to component (F1). "Boron-modified alkenyl succinimide": boron-modified polybutenyl succinic acid monoimide, boron atom (B) content = 1.3 mass%, nitrogen atom (N) content = 1.2 mass%, B / N = 1.08, corresponds to component (F2). <Metal-based detergent> "Neutral Ca salicylate": calcium salicylate with a base number = 64 mg KOH / g, Ca content = 2.3 mass%. <Other additives> "Additive mixture": an additive mixture consisting of a viscosity index improver (Mw = 400,000), a pour point depressant (Mw = 70,000), glycerin monooleate, and a silicone-based antifoaming agent.

[0134] The lubricating oil compositions thus prepared were measured for the content of each element and were subjected to the following evaluation tests. The results are shown in Table 1.

[0135] (1) Copper elution resistance test 100 mL of the prepared lubricating oil composition was added to a glass test tube (diameter 40 mm x length 300 mm) as the test oil, and a polished copper plate (25 mm x 25 mm x 1 mm) was placed in the test oil and immersed. With the copper plate immersed in the test oil, the oil was left to stand for 62 hours at an oil temperature of 140 ° C. while blowing in 2000 ppm by volume of NOx gas relative to the total amount of gas supplied at a flow rate of 12 L / h. The amount of copper eluted in the test oil (unit: mass ppm) was then measured in accordance with JPI-5S-38-2003. The lower the amount of copper elution, the better the lubricating oil composition's resistance to copper elution. In this example, if the amount of copper elution was less than 250 ppm by mass, it was determined that the lubricating oil composition had good copper elution resistance.

[0136] (2) Hot Tube Test Using the prepared lubricating oil composition, an ISOT test was performed for 168 hours under the following test conditions, in which pure water was added while blowing in NOx gas, to prepare a deteriorated oil. <Test Conditions> - Testing machine: ISOT TESTER, manufactured by Yoshida Scientific Instruments Co., Ltd. - Test vessel internal volume: 500 mL - Amount of lubricating oil composition used: 300 mL - NOx gas amount: 2,000 volume ppm based on the total amount of gas supplied - Amount of pure water added: 5 volume % based on the total amount of lubricating oil composition added every 24 hours - Stirring speed: 800 r / min - Test temperature (cycle): (1) 60°C for 4 hours, (2) 95°C for 2 hours, (3) 120°C for 12 hours, and (4) 60°C for 6 hours, and this cycle was repeated. Using the deteriorated oil prepared as described above, a hot tube test was carried out in accordance with JPI-5S-55-99 at a test temperature of 240°C. The degree of discoloration of the glass tube after the test was evaluated using a 21-point scale ranging from 0 (black) to 10 (colorless) (merit score) in increments of 0.5. The higher the score, the better the lubricating oil composition's high-temperature detergency. In this example, a score of 7.0 or higher was determined to be a lubricating oil composition with good high-temperature detergency.

[0137]

[0138] As can be seen from Table 1, the lubricating oil compositions prepared in Examples 1 to 7 contain components (A) to (C), and therefore are considered to have excellent copper elution resistance and to be able to maintain good long-drain properties for a long period of time. The lubricating oil compositions prepared in Examples 1 to 7 also had excellent high-temperature detergency. On the other hand, the lubricating oil compositions prepared in Comparative Examples 1 and 2 contained secondary zinc dialkyldithiophosphate instead of primary zinc dialkyldithiophosphate, but the amount of copper eluted exceeded 250 ppm by mass, resulting in problems with copper elution resistance.

Claims

1. A lubricating oil composition comprising a base oil (A), a hindered amine compound (B), and an organic zinc dithiophosphate (C) having at least one primary alkyl group.

2. The lubricating oil composition according to claim 1, wherein component (C) comprises a compound (C1) represented by the following general formula (c-1). 【Chemistry 1】 [In the above formula, R ｃ１ ~R ｃ４ Each of these is independently a primary alkyl group.

3. The lubricating oil composition according to claim 2, wherein the primary alkyl group has 1 to 7 carbon atoms.

4. The lubricating oil composition according to claim 1 or 2, wherein the content of component (C) is 0.01 to 7.0% by mass on a basis of the total amount of the lubricating oil composition.

5. The lubricating oil composition according to claim 1 or 2, wherein the content of component (B) is 0.60 to 10.0% by mass on a basis of the total amount of the lubricating oil composition.

6. The lubricating oil composition according to claim 1 or 2, wherein the content ratio of component (B) to component (C) [(B) / (C)] is 0.5 to 10.0 by mass.

7. The lubricating oil composition according to claim 1 or 2, wherein component (B) comprises one or more compounds selected from a compound (B1) represented by the following general formula (b-1) and a compound (B2) represented by the following general formula (b-2). 【Chemistry 2】 [In the above formula, R ｂ１ Each of these is independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. R ｂ２ This includes a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring-forming carbon atoms, an aryl group having 6 to 18 ring-forming carbon atoms, a hydroxyl group, an amino group, or -O-CO-R. ｂ３ The group represented by (R ｂ３ (This refers to a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.) Z is an alkylene group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 18 ring-forming carbon atoms, an arylene group having 6 to 18 ring-forming carbon atoms, an oxygen atom, a sulfur atom, or -O-CO-(CH ２ ) ｎ This is a base represented by -CO-O- (where n is an integer from 1 to 20).

8. Furthermore, the lubricating oil composition according to claim 1 or 2 further contains molybdenum dithiocarbamate (D).

9. Furthermore, it contains antioxidant (E), which is not included in ingredient (B). The lubricating oil composition according to claim 1 or 2, wherein component (E) comprises one or more amine-based antioxidants (E1) and phenol-based antioxidants (E2) that do not fall under component (B).

10. Furthermore, it contains an imide compound (F), The lubricating oil composition according to claim 1 or 2, wherein component (F) comprises one or more selected from non-boron-modified alkenyl succinimide (F1) and boron-modified alkenyl succinimide (F2).

11. Component (F) contains component (F1) and component (F2), The lubricating oil composition according to claim 10, wherein the content ratio of component (F1) to component (F2) [(F1) / (F2)] is less than 5.00 by mass.

12. A lubricating oil composition according to claim 1 or 2, used for lubricating an internal combustion engine in a hybrid system.

13. An internal combustion engine, installed in a hybrid system, filled with the lubricating oil composition according to claim 1 or 2.

14. A method for lubricating an internal combustion engine, wherein the lubricating oil composition according to claim 1 or 2 is applied to the internal combustion engine mounted in a hybrid system.

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