Lubricating oil composition

Abstract

To provide a novel lubricating oil composition that has properties suitable for lubrication properties (for example, scuffing resistance, copper elution inhibitory effect, oxidation stability, insulation, and the like) according to various mechanisms incorporated in a device.SOLUTION: There is provided a lubricating oil composition containing a base oil (A), a thiadiazole-based compound (B), and boron-modified alkenyl succinic acid imide (C), and a content of the component (B) is less than 0.60 mass% based on the total amount of the lubricating oil composition, a content ratio [B / N] of boron atoms and nitrogen atoms derived from the component (C) is 0.35 or more in terms of mass ratio, and a content of boron atoms derived from the component (C) is 300 mass ppm or less based on the total amount of the lubricating oil composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a lubricating oil composition, a reducer, and the use of the lubricating oil composition. [Background technology]

[0002] Various devices such as engines, transmissions, reducers, compressors, hydraulic devices, etc. have mechanisms such as torque converters, wet clutches, gear bearing mechanisms, oil pumps, hydraulic control mechanisms, etc. Lubricating oil compositions are used in these mechanisms, and lubricating oil compositions that can meet various requirements have been developed. For example, Patent Document 1 discloses a gear oil composition that aims to provide a gear oil composition that combines fuel-saving performance with sufficient durability of gears, bearings, etc., and that is obtained by blending a low-viscosity mineral oil-based lubricating base oil and a high-viscosity solvent-refined mineral oil-based lubricating oil in a predetermined ratio with a zinc dialkyldithiophosphate and an alkaline earth metal-based detergent in predetermined blending amounts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-193255 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, lubricating oil compositions used in various devices such as electric motors may be required to have, in addition to insulating properties, properties such as anti-scuffing properties, copper elution inhibiting effect, oxidation stability, etc. In other words, there is a demand for new lubricating oil compositions that have properties (e.g., anti-scuffing properties, copper elution inhibiting effect, oxidation stability, insulating properties, etc.) suitable for lubrication according to the various mechanisms incorporated within the devices. [Means for solving the problem]

[0005] The present invention provides a lubricating oil composition that contains a base oil, a thiadiazole compound, and a boron-modified alkenyl succinimide, in which the content of the thiadiazole compound and the contents of boron atoms and nitrogen atoms derived from the boron-modified alkenyl succinimide are adjusted to fall within predetermined ranges. Specifically, the present invention provides a lubricating oil composition, a reducer, and use of the lubricating oil composition according to the following aspects [1] to

[14] . [1] A lubricating oil composition comprising a base oil (A), a thiadiazole compound (B), and a boron-modified alkenyl succinimide (C), The content of component (B) is less than 0.60 mass% based on the total amount of the lubricating oil composition, the content ratio [B / N] of boron atoms and nitrogen atoms derived from component (C) is 0.35 or more in mass ratio; The content of boron atoms derived from component (C) is 300 ppm by mass or less based on the total amount of the lubricating oil composition. Lubricating oil composition. [2] The lubricating oil composition according to [1] above, wherein the content of nitrogen atoms derived from component (C) is 320 mass ppm or less based on the total amount of the lubricating oil composition. [3] The lubricating oil composition according to the above [1] or [2], wherein the content of nitrogen atoms derived from component (C) is 5.0 to 320 ppm by mass based on the total amount of the lubricating oil composition. [4] The lubricating oil composition according to any one of the above [1] to [3], wherein the content ratio [B / N] of boron atoms and nitrogen atoms derived from component (C) is 0.35 to 2.0 in mass ratio. [5] The lubricating oil composition according to any one of the above [1] to [4], wherein the content of boron atoms derived from component (C) is 3.0 to 300 ppm by mass based on the total amount of the lubricating oil composition. [6] The lubricating oil composition according to any one of the above [1] to [5], wherein component (C) comprises a boron-modified alkenyl succinic acid bisimide (C1). [7] The lubricating oil composition according to any one of the above [1] to [6], wherein component (B) comprises a thiadiazole-based compound (B1) having a branched alkyl group. [8] The lubricating oil composition according to any one of the above [1] to [7], wherein the content of the sulfurized olefin is less than 0.20 mass % based on the total amount of the lubricating oil composition. [9] The kinematic viscosity of the lubricating oil composition at 100 ° C. is 2.1 mm 2 / s or more 5.0mm 2 The lubricating oil composition according to any one of the above [1] to [8], wherein the viscosity is less than 1 / s.

[10] The lubricating oil composition according to any one of the above [1] to [9], further comprising one or more phosphorus compounds (D) selected from phosphates and phosphites.

[11] The lubricating oil composition according to the above

[10] , wherein component (D) comprises one or more sulfur-phosphorus compounds (D1) selected from sulfur-containing phosphate esters and sulfur-containing phosphites.

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

[11] , which is used for lubricating a reducer.

[13] A reducer to which the lubricating oil composition according to any one of the above [1] to

[12] is applied.

[14] Use of the lubricating oil composition according to any one of the above [1] to

[12] for lubricating a reducer. [Effects of the Invention]

[0006] A preferred embodiment of the lubricating oil composition of the present invention has properties suitable for various mechanisms incorporated in equipment, and a more preferred embodiment of the lubricating oil composition can improve properties such as scuffing resistance, copper elution suppression effect, oxidation stability, and insulating properties in a well-balanced manner. Therefore, these lubricating oil compositions can be suitably used for lubricating reducers and the like. DETAILED DESCRIPTION OF THE INVENTION

[0007] Regarding the numerical ranges described herein, the upper and lower limits can be combined in any combination. 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, when a numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described herein. In addition, as a numerical range described in this specification, for example, "60 to 100" means a range of "60 or more and 100 or less."

[0008] In this specification, the kinematic viscosity and viscosity index refer to values ​​measured or calculated in accordance with JIS K2283:2000. In this specification, the contents of boron atoms and phosphorus atoms refer to values ​​measured in accordance with JPI-5S-38-92. In this specification, the nitrogen atom content refers to a value measured in accordance with JIS K2609. In this specification, the content of sulfur atoms means a value measured in accordance with JIS K2541-6:2013.

[0009] [Constitution of lubricating oil composition] A lubricating oil composition according to one embodiment of the present invention contains a base oil (A) (hereinafter also referred to as "component (A)"), a thiadiazole-based compound (hereinafter also referred to as "component (B)"), and a boron-modified alkenyl succinimide (hereinafter also referred to as "component (C)"). In the lubrication of sliding contact surfaces such as tooth surfaces of various mechanisms incorporated in equipment, the occurrence of localized surface damage due to solid-phase adhesion, known as scuffing, is a problem. According to the inventors' studies, it has been found that scuffing is more likely to occur in lubricating oil compositions with lower kinematic viscosity. Furthermore, lubricating oil compositions with low kinematic viscosity also exhibit a decrease in volume resistivity, which can easily cause problems with insulation. The present inventors have found that a lubricating oil composition containing a thiadiazole compound improves scuffing resistance, but at the same time, they have found that new problems arise, such as an increased amount of copper elution and a decrease in oxidation stability. As a result of extensive investigations to solve these problems, the present inventors have discovered that a lubricating oil composition in which the content of the thiadiazole compound and the content of boron atoms and nitrogen atoms derived from the boron-modified alkenyl succinimide are adjusted within predetermined ranges can be produced, resulting in a lubricating oil composition with a well-balanced improvement in properties such as scuffing resistance, copper elution suppression effect, oxidation stability, and insulating properties. The lubricating oil composition of one embodiment of the present invention has been developed based on this finding.

[0010] From the viewpoint of providing a lubricating oil composition with further improved wear resistance, the lubricating oil composition of one embodiment of the present invention preferably further contains one or more phosphorus-based compounds (D) (hereinafter also referred to as "component (D)") selected from phosphate esters and phosphites. Furthermore, the lubricating oil composition of one embodiment of the present invention may further contain various additives other than components (B) to (D) as needed, provided that the effects of the present invention are not impaired.

[0011] 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 70 mass% or more, still more preferably 75 mass% or more, and particularly preferably 80 mass% or more. It may also be 85 mass% or more, 90 mass% or more, or 92 mass% or more, and may also be 100 mass% or less, 99.5 mass% or less, 99.0 mass% or less, 98.5 mass% or less, 98.0 mass% or less, 97.5 mass% or less, 97.0 mass% or less, 96.5 mass% or less, or 96.0 mass% or less.

[0012] In the lubricating oil composition of one embodiment of the present invention, the total content of components (A), (B), (C) and (D) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably greater than 50 mass%, more preferably greater than 60 mass%, even more preferably greater than 70 mass%, still more preferably greater than 75 mass%, and particularly preferably greater than 80 mass%. It may also be greater than 83 mass%, greater than 85 mass%, greater than 87 mass%, greater than 90 mass%, greater than 92 mass%, or 94 mass% or more, or may be 100 mass% or less, 99.9 mass% or less, 99.5 mass% or less, 99.0 mass% or less, 98.5 mass% or less, 98.0 mass% or less, 97.5 mass% or less, 97.0 mass% or less, 96.5 mass% or less, or 96.0 mass% or less. Hereinafter, each component contained in the lubricating oil composition of one embodiment of the present invention will be described in detail.

[0013] <Component (A): Base oil> The base oil, which is component (A) used in one embodiment of the present invention, 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 paraffinic crude oil, intermediate crude oil, and naphthenic crude oil; distillates obtained by vacuum distillation of these atmospheric residues; and refined oils obtained by subjecting the distillates to one or more refining processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining (hydrocracking).

[0014] Examples of synthetic oils include poly-α-olefins such as α-olefin homopolymers or α-olefin copolymers (e.g., 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)).

[0015] Component (A) used in one embodiment of the present invention preferably contains one or more selected from mineral oils classified into Group 2 and Group 3 of the API (American Petroleum Institute) base oil category and synthetic oils.

[0016] The kinematic viscosity at 100°C of the component (A) used in one embodiment of the present invention is preferably 1.9 mm 2 / s or more, preferably 2.0 mm 2 / s or more, preferably 2.1 mm 2 / s or more, more preferably 2.2 mm 2 / s or more, and 2.3 mm 2 / s or more, 2.5mm 2 / s or more, 2.7mm 2 / s or more, 2.9 mm 2 / s or more, 3.0mm 2 / s or more, 3.2mm 2 / s or more, 3.4mm 2 / s or more, or 3.6 mm 2 / s or more, and preferably 5.0 mm 2 / s or less, preferably 4.8 mm 2 / s or less, preferably 4.6 mm 2 / s or less, more preferably 4.5 mm 2 / s or less, and even more preferably 4.3 mm 2 / s or less, particularly preferably 4.2 mm 2 / s or less, and further, 4.0 mm 2 / s or less, 3.8mm 2 / s or less, 3.7mm 2 / s or less, 3.6mm 2 / s or less, 3.5mm 2 / s or less, 3.4mm 2 / s or less, 3.3mm 2 / s or less, 3.2mm 2 / s or less, 3.0mm 2 / s or less, 2.8mm 2 / s or less, or 2.6 mm 2 / s or less may be used.

[0017] Furthermore, the viscosity index of the component (A) used in one embodiment of the present invention is preferably 70 or greater, more preferably 80 or greater, even more preferably 90 or greater, and even more preferably 100 or greater.

[0018] In one embodiment of the present invention, when a mixed oil of two or more base oils is used as component (A), the mixed oil preferably has a kinematic viscosity and viscosity index within the above ranges. Therefore, a low-viscosity base oil and a high-viscosity base oil may be used in combination to adjust the kinematic viscosity and viscosity index within the above ranges.

[0019] 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 45 mass% or more, more preferably 50 mass% or more, more preferably 55 mass% or more, even more preferably 60 mass% or more, still more preferably 65 mass% or more, particularly preferably 70 mass% or more, and may further be 75 mass% or more, 80 mass% or more, 85 mass% or more, 90 mass% or more, or 92 mass% or more. Also, it is preferably 99.99 mass% or less, more preferably 99.90 mass% or less, more preferably 99.50 mass% or less, even more preferably 99.00 mass% or less, still more preferably 98.50 mass% or less, particularly preferably 98.00 mass% or less, and may further be 97.50 mass% or less, 97.00 mass% or less, 96.50 mass% or less, or 96.00 mass% or less.

[0020] <Component (B): Thiadiazole-based compound> The lubricating oil composition of one embodiment of the present invention can be a lubricating oil composition with improved scuffing resistance by containing a thiadiazole compound as component (B). The effect of improving scuffing resistance by component (B) can be more effectively exhibited even in lubricating oil compositions with reduced viscosity. The component (B) may be used alone or in combination of two or more types. However, component (B) can also cause an increase in copper elution and a decrease in oxidation stability, and therefore, in the lubricating oil composition of one embodiment of the present invention, the content of component (B) is limited to less than 0.60 mass % based on the total amount (100 mass %) of the lubricating oil composition.

[0021] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of obtaining a lubricating oil composition having good copper elution inhibiting effect and oxidation stability, the content of component (B) is less than 0.60% by mass, preferably 0.57% by mass or less, more preferably 0.55% by mass or less, more preferably 0.52% by mass or less, more preferably 0.50% by mass or less, even more preferably 0.47% by mass or less, even more preferably 0.45% by mass or less, even more preferably 0.42% by mass or less, still more preferably 0.40% by mass or less, particularly preferably 0.39% by mass or less, and may even be 0.38% by mass or less, 0.37% by mass or less, 0.36% by mass or less, 0.35% by mass or less, 0.34% by mass or less, 0.33% by mass or less, or 0.32% by mass or less, based on the total amount (100% by mass) of the lubricating oil composition.

[0022] Furthermore, in the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with further improved scuffing resistance, the content of component (B) 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 0.07 mass% or more, more preferably 0.10 mass% or more, even more preferably 0.12 mass% or more, even more preferably 0.15 mass% or more, even more preferably 0.17 mass% or more, still more preferably 0.20 mass% or more, particularly preferably 0.22 mass% or more, and may even be 0.23 mass% or more, 0.24 mass% or more, 0.25 mass% or more, 0.26 mass% or more, 0.27 mass% or more, or 0.28 mass% or more.

[0023] In the lubricating oil composition of one aspect of the present invention, the content of component (B) in terms of sulfur atoms, based on the total amount (100% by mass) of the lubricating oil composition, is preferably 30 ppm by mass or more, more preferably 50 ppm by mass or more, more preferably 100 ppm by mass or more, more preferably 150 ppm by mass or more, even 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, still more preferably 400 ppm by mass or more, particularly preferably 500 ppm by mass or more, and even more preferably 600 ppm by mass or more, 650 ppm by mass or more, 700 ppm by mass or more, 750 ppm by mass or more, 800 ppm by mass or more, 850 ppm by mass or more, It may be 900 ppm by mass or more, 950 ppm by mass or more, or 1000 ppm by mass or more, and from the viewpoint of obtaining a lubricating oil composition with good copper elution suppression effect and oxidation stability, it is preferably 2500 ppm by mass or less, more preferably 2000 ppm by mass or less, more preferably 1900 ppm by mass or less, more preferably 1800 ppm by mass or less, even more preferably 1700 ppm by mass or less, even more preferably 1600 ppm by mass or less, even more preferably 1500 ppm by mass or less, still more preferably 1400 ppm by mass or less, particularly preferably 1300 ppm by mass or less, and may further be 1250 ppm by mass or less, 1200 ppm by mass or less, 1150 ppm by mass or less, 1100 ppm by mass or less, or 1050 ppm by mass or less.

[0024] In the lubricating oil composition of one aspect of the present invention, the content of component (B) calculated as nitrogen atoms, based on the total amount (100 mass%) of the lubricating oil composition, is preferably 10 ppm by mass or more, more preferably 30 ppm by mass or more, more preferably 50 ppm by mass or more, more preferably 60 ppm by mass or more, even more preferably 70 ppm by mass or more, even more preferably 80 ppm by mass or more, even more preferably 90 ppm by mass or more, still more preferably 100 ppm by mass or more, particularly preferably 120 ppm by mass or more, and even more preferably 130 ppm by mass or more, 140 ppm by mass or more, 150 ppm by mass or more, 160 ppm by mass or more, 170 ppm by mass or more, 180 ppm by mass or more, and pm or more, or 190 ppm by mass or more, and from the viewpoint of obtaining a lubricating oil composition with good copper elution suppression effect and oxidation stability, the copper content is preferably 500 ppm by mass or less, more preferably 450 ppm by mass or less, more preferably 400 ppm by mass or less, more preferably 350 ppm by mass or less, even more preferably 320 ppm by mass or less, even more preferably 300 ppm by mass or less, even more preferably 290 ppm by mass or less, still more preferably 280 ppm by mass or less, particularly preferably 270 ppm by mass or less, and may further be 260 ppm by mass or less, 250 ppm by mass or less, 240 ppm by mass or less, 230 ppm by mass or less, 220 ppm by mass or less, 210 ppm by mass or less, or 200 ppm by mass or less.

[0025] The thiadiazole compound, component (B) used in one embodiment of the present invention, may be any compound having a thiadiazole ring. From the viewpoint of obtaining a lubricating oil composition with improved scuffing resistance, it preferably contains a compound represented by any one of the following general formulas (b-1) to (b-4), and more preferably contains a compound represented by the following general formula (b-1): The component (B) may be used alone or in combination of two or more types.

[0026] [ka]

[0027] In the above formula, R 1 and R 2 are each independently a hydrocarbon group. m and n are each independently an integer of 1 to 10, but from the viewpoint of obtaining a lubricating oil composition with further improved scuffing resistance, they are preferably integers of 1 to 6, more preferably integers of 1 to 4, even more preferably integers of 2 or 3, and still more preferably 2.

[0028] R 1 and R 2 Examples of the hydrocarbon group that can be selected include linear or branched alkyl groups such as methyl, ethyl, propyl (n-propyl, isopropyl), butyl (n-butyl, s-butyl, t-butyl, isobutyl), pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, 1,1-dimethylheptyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups; ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecyl groups; Examples of such groups include linear or branched alkenyl groups such as decenyl, tridecenyl, tetradecenyl, and pentadecenyl; cycloalkyl groups which may have an alkyl group such as cyclohexyl, dimethylcyclohexyl, ethylcyclohexyl, propylcyclohexyl, butylcyclohexyl, and heptylcyclohexyl; aryl groups such as phenyl, naphthyl, anthracenyl, biphenyl, and terphenyl; alkylaryl groups such as tolyl, dimethylphenyl, butylphenyl, nonylphenyl, methylbenzyl, and dimethylnaphthyl; and arylalkyl groups such as phenylmethyl, phenylethyl, and diphenylmethyl.

[0029] R 1 and R 2From the viewpoint of obtaining a lubricating oil composition with further improved scuffing resistance, the number of carbon atoms in the hydrocarbon group that can be selected as above is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and still more preferably 5 or more, and is preferably 30 or less, more preferably 20 or less, even more preferably 16 or less, and still more preferably 12 or less.

[0030] Among these, R 1 and R 2 are each independently preferably an alkyl group from the viewpoint of providing a lubricating oil composition with improved scuffing resistance, and are more preferably branched-chain alkyl groups, and even more preferably branched-chain alkyl groups having 5 or more carbon atoms, from the viewpoint of providing a lubricating oil composition that can improve copper corrosion prevention properties as well as scuffing resistance and effectively suppress copper elution. From the above viewpoints, the number of carbon atoms in the branched chain alkyl group is preferably 5 or more, more preferably 7 or more, even more preferably 8 or more, and still more preferably 9 or more, and is preferably 30 or less, more preferably 20 or less, even more preferably 16 or less, and still more preferably 12 or less.

[0031] In one embodiment of the lubricating oil composition of the present invention, from the viewpoint of providing a lubricating oil composition with further improved scuffing resistance, the total content of the compounds represented by any one of the general formulas (b-1) to (b-4) is preferably 60 to 100 mass%, 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.

[0032] From the above viewpoints, the content of the compound represented by general formula (b-1) in the lubricating oil composition of one embodiment of the present invention is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, still more preferably 80 to 100 mass%, and particularly preferably 90 to 100 mass%, based on the total amount (100 mass%) of component (B) contained in the lubricating oil composition.

[0033] In the lubricating oil composition of one embodiment of the present invention, the content of the compound represented by the following general formula (bx) is preferably less than 10 mass%, more preferably less than 8 mass%, even more preferably less than 5 mass%, still more preferably less than 3 mass%, and particularly preferably less than 1 mass%, based on the total amount (100 mass%) of component (B) contained in the lubricating oil composition. [ka] [In the above formula, R a is a hydrogen atom or a methyl group, and R b is an alkyl group having 1 to 4 carbon atoms. p is 0 or 1.

[0034] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of further improving scuffing resistance and providing a lubricating oil composition with a good copper elution suppression effect, it is preferred that component (B) contains a thiadiazole-based compound (B1) having a branched alkyl group (hereinafter also referred to as "component (B1)"). From the above viewpoints, the content of component (B1) is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, 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.

[0035] From the viewpoint of further improving scuffing resistance and providing a lubricating oil composition with a good copper elution suppression effect, the carbon number of the branched alkyl group in component (B1) is preferably 5 or more, more preferably 7 or more, even more preferably 8 or more, and still more preferably 9 or more; and is preferably 30 or less, more preferably 20 or less, even more preferably 16 or less, and still more preferably 12 or less.

[0036] From the viewpoint of providing a lubricating oil composition with improved scuffing resistance and a good copper elution suppression effect, component (B1) is represented by any one of the general formulas (b-1) to (b-4), and R in each formula is 1 and R 2 are each independently a branched chain alkyl group, and are preferably compounds represented by the general formula (b-1), 1 and R 2 are each independently a branched chain alkyl group. The preferred range of the carbon number of the branched chain alkyl group is as described above.

[0037] <Olefin sulfide> The lubricating oil composition of one embodiment of the present invention may contain a sulfurized olefin to the extent that the effects of the present invention are not impaired, however, from the viewpoint of obtaining a lubricating oil composition with good scuffing resistance, copper elution suppression effect, oxidation stability, and insulating properties, the lower the content of the sulfurized olefin, the better. In view of the above, in the lubricating oil composition of one embodiment of the present invention, the content of sulfurized olefin is, based on the total amount (100 mass%) of the lubricating oil composition, preferably less than 0.20 mass%, more preferably less than 0.18 mass%, more preferably less than 0.15 mass%, even more preferably less than 0.12 mass%, still more preferably less than 0.10 mass%, particularly preferably less than 0.07 mass%, and may even be less than 0.05 mass%, less than 0.04 mass%, less than 0.03 mass%, less than 0.02 mass%, less than 0.01 mass%, or less than 0.001 mass%.

[0038] Examples of sulfurized olefins include compounds represented by the following general formula (i). R-(S) q -R' (i) In the above formula (i), R is an alkenyl group having 2 to 20 carbon atoms, R' is an alkenyl group having 2 to 20 carbon atoms or an alkyl group having 2 to 20 carbon atoms, and q is an integer of 1 to 10.

[0039] <Component (C): Boron-modified alkenyl succinimide> A lubricating oil composition according to one embodiment of the present invention contains a boron-modified alkenyl succinimide as component (C). As described above, component (B) contributes to improving scuffing resistance, but at the same time, it also contributes to increasing the amount of copper elution and reducing oxidation stability. Therefore, a lubricating oil composition according to one embodiment of the present invention contains component (C) in addition to component (B), thereby achieving a lubricating oil composition that exhibits excellent scuffing resistance, copper elution suppression effect, and oxidation stability. The component (C) may be used alone or in combination of two or more types.

[0040] In the lubricating oil composition of one embodiment of the present invention, component (C) satisfies the following requirements (I) and (II). Requirement (I): The ratio of the content of boron atoms to nitrogen atoms [B / N] derived from component (C) is 0.35 or more in mass ratio. Requirement (II): The content of boron atoms derived from component (C) is 300 mass ppm or less based on the total amount of the lubricating oil composition. By setting the content ratio [B / N] to 0.35 or more so as to satisfy requirement (I), it is possible to obtain a lubricating oil composition with improved copper elution suppression effect and oxidation stability. Furthermore, by adjusting the content of boron atoms derived from component (C) so as to satisfy requirement (II), it is possible to obtain a lubricating oil composition that maintains good anti-scuffing properties and insulating properties.

[0041] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with improved copper elution suppression effect and improved oxidation stability, the content ratio [B / N] of boron atoms to nitrogen atoms derived from component (C) is, in mass ratio, 0.35 or more as required by requirement (I) above, preferably 0.40 or more, more preferably 0.45 or more, more preferably 0.50 or more, more preferably 0.55 or more, even more preferably 0.60 or more, even more preferably 0.65 or more, even more preferably 0.70 or more, still more preferably 0.75 or more, particularly preferably 0.80 or more, and may even be 0.85 or more, or 0.90 or more. The content ratio [B / N] of boron atoms to nitrogen atoms derived from component (C) may be 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, or 1.3 or less by mass.

[0042] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition that maintains good scuffing resistance and insulating properties, the content of boron atoms derived from component (C) is 300 ppm by mass or less, preferably 280 ppm by mass or less, more preferably 250 ppm by mass or less, more preferably 220 ppm by mass or less, more preferably 200 ppm by mass or less, even more preferably 180 ppm by mass or less, even more preferably 160 ppm by mass or less, even more preferably 150 ppm by mass or less, still more preferably 140 ppm by mass or less, particularly preferably 130 ppm by mass or less, and may even be 125 ppm by mass or less, 120 ppm by mass or less, 115 ppm by mass or less, or 110 ppm by mass or less, based on the total amount (100% by mass) of the lubricating oil composition. Furthermore, from the viewpoint of obtaining a lubricating oil composition having excellent copper elution suppression effect and oxidation stability, the content of boron atoms derived from component (C) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 3.0 ppm by mass or more, more preferably 5.0 ppm by mass or more, more preferably 7.0 ppm by mass or more, more preferably 10.0 ppm by mass or more, even more preferably 12.0 ppm by mass or more, even more preferably 15.0 ppm by mass or more, even more preferably 17.0 ppm by mass or more, still more preferably 20.0 ppm by mass or more, particularly preferably 22.0 ppm by mass or more, and even further, 25.0 ppm by mass or more, 30.0 ppm by mass or more, 35.0 ppm by mass or more, 40.0 ppm by mass or more, 45.0 ppm by mass or more, 50.0 ppm by mass or more, 55.0 ppm by mass or more, 60.0 ppm by mass or more, 65.0 ppm by mass or more, 70.0 ppm by mass or more, or 75.0 ppm by mass or more.

[0043] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of better maintaining anti-scuffing properties and insulating properties and providing a lubricating oil composition that is excellent in copper elution suppression effect and oxidation stability, the content of nitrogen atoms derived from component (C) is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 5.0 ppm by mass or more, more preferably 7.0 ppm by mass or more, more preferably 9.0 ppm by mass or more, more preferably 10.0 ppm by mass or more, even more preferably 12.0 ppm by mass or more, even more preferably 15.0 ppm by mass or more, even more preferably 17.0 ppm by mass or more, still more preferably 20.0 ppm by mass or more, particularly preferably 22.0 ppm by mass or more, and even more preferably 25.0 ppm by mass or more, 30.0 ppm by mass or more, 35.0 ppm by mass or more, 40.0 ppm by mass or more, 45.0 ppm by mass or more, 50 ... It may be 5.0 ppm by mass or more, 60.0 ppm by mass or more, 65.0 ppm by mass or more, 70.0 ppm by mass or more, 75.0 ppm by mass or more, 80 ppm by mass or more, or 85 ppm by mass or more, and is preferably 320 ppm by mass or less, more preferably 300 ppm by mass or less, more preferably 280 ppm by mass or less, more preferably 250 ppm by mass or less, even more preferably 220 ppm by mass or less, even more preferably 200 ppm by mass or less, even more preferably 180 ppm by mass or less, still more preferably 160 ppm by mass or less, particularly preferably 150 ppm by mass or less, and may also be 140 ppm by mass or less, 135 ppm by mass or less, 130 ppm by mass or less, 125 ppm by mass or less, 120 ppm by mass or less, 115 ppm by mass or less, 110 ppm by mass or less, 105 ppm by mass or less, or 100 ppm by mass or less.

[0044] The component (C) used in one embodiment of the present invention may be at least one selected from boron-modified alkenyl succinic acid bisimides (C1) and boron-modified alkenyl succinic acid monoimides (C2). From the viewpoint of providing a lubricating oil composition that exhibits excellent anti-scuffing properties, copper elution suppression effect, and oxidation stability, it is preferable that component (C) used in one embodiment of the present invention contains a boron-modified alkenyl succinic acid bisimide (C1). From the above viewpoints, the content of component (C1) is preferably 20 to 100 mass%, more preferably 40 to 100 mass%, more preferably 50 to 100 mass%, even more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, still more preferably 80 to 100 mass%, and particularly preferably 90 to 100 mass%, based on the total amount (100 mass%) of component (C) contained in the lubricating oil composition.

[0045] Component (C1) includes a boron-modified compound represented by the general formula (c-1) above, and component (C2) includes a boron-modified compound represented by the general formula (c-2) above.

[0046] [ka]

[0047] In the above general formulas (c-1) and (c-2), R a1 , R a2 and R a3 are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 3000 (preferably 900 to 2500). R a1 , R a2 and R a3 Examples of the alkenyl group that can be selected 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. R b1 , R b2 and R b3 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.

[0048] <Ashless dispersants other than component (C)> The lubricating oil composition of one embodiment of the present invention may contain an ashless dispersant other than component (C) to the extent that the effects of the present invention are not impaired. Ashless dispersants other than component (C) include non-boron-modified alkenyl succinimides and alkenyl succinimides modified with other than boron. Examples of non-boron-modified alkenyl succinimides include alkenyl succinic acid bisimides represented by the general formula (c-1) and alkenyl succinic acid monoimides represented by the general formula (c-2). Examples of the alkenyl succinimide modified with a compound other than boron include reaction products obtained by reacting a compound represented by the general formula (c-1) or (c-2) with one or more compounds selected from the group consisting of alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, and organic acids.

[0049] In the lubricating oil composition of one embodiment of the present invention, the content of ashless dispersants other than component (C) may be, based on the total amount (100 mass%) of the lubricating oil composition, 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, 2.0 mass% or less, 1.0 mass% or less, 0.7 mass% or less, 0.5 mass% or less, 0.3 mass% or less, 0.2 mass% or less, or 0.1 mass% or less, or may be 0 mass% or more, 0.001 mass% or more, or 0.01 mass% or more.

[0050] <Component (D): Phosphorus-based compound> From the viewpoint of providing a lubricating oil composition with further improved wear resistance, the lubricating oil composition of one embodiment of the present invention preferably further contains one or more phosphorus-based compounds (D) selected from phosphate esters and phosphites.

[0051] Examples of the phosphate ester used as component (D) in one embodiment of the present invention include a neutral phosphate ester represented by the following general formula (d-1) and an acidic phosphate ester represented by the following general formula (d-2) or (d-3). Furthermore, examples of the phosphite ester used as component (D) in one embodiment of the present invention include acid phosphites represented by the following general formula (d-4) or (d-5).

[0052] [ka]

[0053] In the above formula, R A are each independently an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 18 carbon atoms which may be substituted with an alkyl group having 1 to 6 carbon atoms, a group having a sulfide bond, etc. A may be the same or different from each other.

[0054] R A 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, a hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a hexadecyl group, and an octadecyl group. These alkyl groups may be straight-chain alkyl groups or branched-chain alkyl groups. The alkyl group has 1 to 30 carbon atoms, preferably 3 to 20 carbon atoms, more preferably 5 to 16 carbon atoms, even more preferably 6 to 14 carbon atoms, and even more preferably 8 to 12 carbon atoms.

[0055] R A Examples of the alkenyl group that can be selected as the alkenyl group include an ethenyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, and an octadecenyl group. These alkenyl groups may be straight-chain alkenyl groups or branched-chain alkenyl groups. The alkenyl group has 2 to 20 carbon atoms, preferably 3 to 16 carbon atoms, and more preferably 6 to 12 carbon atoms.

[0056] R A Examples of the aryl group that can be selected as include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a biphenyl group, a terphenyl group, and a phenylnaphthyl group, with a phenyl group being preferred. Examples of the "alkyl group having 1 to 6 carbon atoms" that can substitute for these aryl groups include the alkyl groups having 1 to 6 carbon atoms mentioned above.

[0057] R A As the group having a sulfide bond that can be selected as the group, a group represented by the following general formula (ii) is preferred. [ka] In the above formula (ii), R A01 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. A02 is a divalent organic group. x is an integer of 1 or more, preferably an integer of 1 to 10, more preferably an integer of 1 to 5, even more preferably an integer of 1 to 3, still more preferably 1 or 2, and particularly preferably 1. * indicates a bonding position.

[0058] R A01 Examples of the monovalent organic group that can be selected as aryl include an alkyl group, an alkenyl group, and an aryl group. An alkyl group having 1 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms in which at least one -CH2- structure is substituted with -O-, -S-, -COO-, -OCO-, -CSO-, -OCS-, -CH=CH-, or -C≡C- is preferred, and an alkyl group is more preferred. R A01 The alkyl group that can be selected as may be a straight-chain alkyl group or a branched-chain alkyl group, but is preferably a straight-chain alkyl group. The alkyl group has 1 to 20 carbon atoms, preferably 2 to 18, more preferably 4 to 16, even more preferably 6 to 12, and even more preferably 8 to 10 carbon atoms.

[0059] R A02 Examples of the divalent organic group that can be selected as are alkylene groups having 1 to 20 carbon atoms, cycloalkylene groups, alkenylene groups having 1 to 20 carbon atoms, cycloalkenylene groups, and arylene groups. An alkylene group having 1 to 20 carbon atoms or an alkylene group having 1 to 20 carbon atoms in which at least one -CH2- structure is substituted with -O-, -S-, -COO-, -OCO-, -CSO-, -OCS-, -CH=CH-, or -C≡C- is preferred, and an alkylene group having 2 to 20 carbon atoms is more preferred. R A02 The alkylene group that can be selected as may be a straight-chain alkylene group or a branched-chain alkylene group, but is preferably a straight-chain alkylene group. The alkylene group has 1 to 20 carbon atoms, preferably 1 to 12, more preferably 1 to 8, even more preferably 1 to 4, still more preferably 1, 2 or 4, and particularly preferably 2.

[0060] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with further improved wear resistance, it is preferred that component (D) contains one or more sulfur-phosphorus compounds (D1) selected from sulfur-containing phosphate esters and sulfur-containing phosphites.

[0061] In one embodiment of the lubricating oil composition of the present invention, from the viewpoint of providing a lubricating oil composition with further improved wear resistance, the content of component (D1) is preferably 60 to 100 mass%, more preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, still more preferably 95 to 100 mass%, and particularly preferably 98 to 100 mass%, based on the total amount (100 mass%) of component (D) contained in the lubricating oil composition.

[0062] Examples of the sulfur atom-containing phosphate ester and sulfur atom-containing phosphite ester include sulfur atom-containing phosphate esters and sulfur atom-containing phosphites having a group represented by the above formula (ii). From the viewpoint of providing a lubricating oil composition with further improved wear resistance, component (D1) used in one embodiment of the present invention is preferably a sulfur atom-containing phosphite ester having a group represented by formula (ii) above, and more preferably at least one selected from compound (D11) represented by general formula (d-11) below and compound (D12) represented by general formula (d-12) below:

[0063] [ka]

[0064] In the formulas (d-11) and (d-12), R A11 , R A21 and R A22 are each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. The alkyl group may be a straight-chain alkyl group or a branched-chain alkyl group, but is preferably a straight-chain alkyl group. The alkyl group has 1 to 20 carbon atoms, preferably 2 to 18, more preferably 4 to 16, even more preferably 6 to 12, and even more preferably 8 to 10 carbon atoms. Furthermore, a1, a2, and a3 are each independently an integer of 1 to 20, preferably an integer of 1 to 12, more preferably an integer of 1 to 8, even more preferably an integer of 1 to 4, still more preferably 1, 2, or 4, and particularly preferably 2.

[0065] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with further improved wear resistance, it is further preferred that component (D) contains both a compound (D11) represented by general formula (d-11) above and a compound (D12) represented by general formula (d-12) above. In one embodiment of the present invention, the content ratio of compound (D11) to compound (D12) [(D11) / (D12)] is, in mass ratio, preferably 1 / 20 to 20 / 1, more preferably 1 / 16 to 10 / 1, more preferably 1 / 14 to 5 / 1, even more preferably 1 / 12 to 2 / 1, still more preferably 1 / 11 to 1 / 1, and particularly preferably 1 / 10 to 1 / 2.

[0066] The acidic phosphate ester and acidic phosphite ester used as component (D) in one embodiment of the present invention may be in the form of an amine salt. The amine that forms the amine salt is preferably a compound represented by the following general formula (di): The amine may be used alone or in combination of two or more kinds. [ka]

[0067] In the above general formula (di), r is an integer of 1 to 3, and is preferably 1. R x are each independently an alkyl group having 6 to 18 carbon atoms, an alkenyl group having 6 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a hydroxyalkyl group having 6 to 18 carbon atoms. In addition, R x If there are multiple R x may be the same or different from each other.

[0068] R x The alkyl group having 6 to 18 carbon atoms, the alkenyl group having 6 to 18 carbon atoms, and the aryl group having 6 to 18 carbon atoms that can be selected as R 11 ~R 13 and R 21 ~R 23 Among the groups exemplified as the alkyl group, alkenyl group, and aryl group that can be selected as the aryl group, groups having a carbon number within the above ranges can be mentioned. Furthermore, examples of the hydroxyalkyl group having 6 to 18 carbon atoms include groups in which a hydrogen atom in an alkyl group having 6 to 18 carbon atoms has been substituted with a hydroxy group, and specific examples thereof include a hydroxyhexyl group, a hydroxyoctyl group, a hydroxydodecyl group, and a hydroxytridecyl group.

[0069] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with further improved wear resistance, the content of component (D) 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, even more preferably 0.07 mass% or more, still more preferably 0.10 mass% or more, particularly preferably 0.15 mass% or more, and even further preferably 0.17 mass% or more, 0.20 mass% or more, 0.23 mass% or more, 0.25 mass% or more, 0.27 mass% or more, or 0.30% by mass or more, and is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, even more preferably 2.0% by mass or less, still more preferably 1.5% by mass or less, particularly preferably 1.2% by mass or less, and may further be 1.0% by mass or less, 0.95% by mass or less, 0.90% by mass or less, 0.85% by mass or less, 0.80% by mass or less, 0.75% by mass or less, 0.70% by mass or less, 0.65% by mass or less, 0.60% by mass or less, 0.55% by mass or less, or 0.50% by mass or less.

[0070] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with further improved wear resistance, the content of component (D) in terms of phosphorus atoms is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 30 ppm by mass or more, more preferably 50 ppm by mass or more, more preferably 70 ppm by mass or more, more preferably 100 ppm by mass or more, even more preferably 120 ppm by mass or more, even more preferably 150 ppm by mass or more, even more preferably 180 ppm by mass or more, still more preferably 200 ppm by mass or more, still more preferably 220 ppm by mass or more, still more preferably 250 ppm by mass or more, particularly preferably 270 ppm by mass or more, and is preferably 800 ppm by mass or less, more preferably 700 ppm by mass or less, even more preferably 600 ppm by mass or less, still more preferably 500 ppm by mass or less, and particularly preferably 450 ppm by mass or less.

[0071] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with further improved wear resistance, the content of component (D) in terms of sulfur atoms is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 50 ppm by mass or more, more preferably 70 ppm by mass or more, more preferably 100 ppm by mass or more, more preferably 120 ppm by mass or more, even more preferably 150 ppm by mass or more, even more preferably 180 ppm by mass or more, even more preferably 200 ppm by mass or more, still more preferably 220 ppm by mass or more, even more preferably 250 ppm by mass or more, still more preferably 270 ppm by mass or more, particularly preferably 300 ppm by mass or more, and is preferably 800 ppm by mass or less, more preferably 700 ppm by mass or less, even more preferably 600 ppm by mass or less, still more preferably 500 ppm by mass or less, and particularly preferably 450 ppm by mass or less.

[0072] In the lubricating oil composition of one embodiment of the present invention, the content of the sulfur-atom-free acidic phosphate ester, calculated as phosphorus atoms, may be less than 100 ppm by mass, less than 50 ppm by mass, less than 10 ppm by mass, less than 8 ppm by mass, less than 5 ppm by mass, less than 3 ppm by mass, or less than 1 ppm by mass, based on the total amount (100% by mass) of the lubricating oil composition.

[0073] In addition, in the lubricating oil composition of one embodiment of the present invention, the content of the sulfur-atom-free neutral phosphate ester, calculated as phosphorus atoms, based on the total amount (100 mass%) of the lubricating oil composition may be less than 50 ppm by mass, less than 10 ppm by mass, less than 8 ppm by mass, less than 5 ppm by mass, less than 3 ppm by mass, or less than 1 ppm by mass.

[0074] <Various additives other than components (B) to (D)> The lubricating oil composition of one embodiment of the present invention may contain various additives other than components (B) to (D) as needed, provided that the effects of the present invention are not impaired. Examples of such various additives include pour point depressants, antioxidants, metal detergents, metal deactivators, friction modifiers, rust inhibitors, and antifoaming agents. These lubricating oil additives may be used alone or in combination of two or more.

[0075] 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.

[0076] [Pour point depressants] 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 paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, and polyalkylstyrenes.

[0077] [Antioxidants] The lubricating oil composition of one embodiment of the present invention may further contain an antioxidant. The antioxidants may be used alone or in combination of two or more. Examples of antioxidants used in one embodiment of the present invention include amine-based antioxidants such as alkylated diphenylamine, phenylnaphthylamine, and alkylated phenylnaphthylamine; and phenol-based antioxidants such as 2,6-di-t-butylphenol, 4,4'-methylenebis(2,6-di-t-butylphenol), isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate. In the lubricating oil composition of one embodiment of the present invention, it is preferred to use an amine-based antioxidant and a phenol-based antioxidant in combination.

[0078] [Metallic detergents] The lubricating oil composition of one embodiment of the present invention may further contain a metallic detergent. The metallic detergent may be used alone or in combination of two or more kinds. Examples of the metal-based detergent used in one embodiment of the present invention include metal salts such as metal sulfonates, metal salicylates, and metal phenates. The metal atom constituting the metal salt is preferably a metal atom selected from alkali metals and alkaline earth metals, more preferably sodium, calcium, magnesium, or barium, and even more preferably calcium.

[0079] In the lubricating oil composition of one embodiment of the present invention, the metallic detergent preferably contains one or more selected from calcium sulfonate, calcium salicylate, and calcium phenate, and more preferably contains calcium sulfonate. The calcium sulfonate content is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, and still more preferably 80 to 100 mass%, based on the total amount (100 mass%) of metallic detergents contained in the lubricating oil composition.

[0080] The base number of the metallic detergent is preferably 0 to 600 mgKOH / g. However, in the lubricating oil composition of one embodiment of the present invention, the metallic detergent is preferably an overbased metallic detergent having a base number of 100 mgKOH / g or more. The base number of the overbased metallic detergent is 100 mgKOH / g or more, preferably 150 to 500 mgKOH / g, and more preferably 200 to 450 mgKOH / g. In this specification, the term "base number" refers to the base number measured by the perchloric acid method in accordance with 7. of JIS K2501:2003 "Petroleum products and lubricants - Test method for neutralization number."

[0081] [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-based compounds, tolyltriazole-based compounds, imidazole-based compounds, and pyrimidine-based compounds.

[0082] [Friction modifier] The lubricating oil composition of one embodiment of the present invention may further contain a friction modifier. The friction modifier may be used alone or in combination of two or more types. Examples of friction modifiers used in one embodiment of the present invention include molybdenum-based friction modifiers such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid; ashless friction modifiers such as aliphatic amines, fatty acid esters, fatty acid amides, fatty acids, fatty alcohols, and aliphatic ethers, each having at least one alkyl or alkenyl group having 6 to 30 carbon atoms in the molecule; oils and fats, amines, amides, and sulfurized esters.

[0083] [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 kinds. 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.

[0084] [Antifoaming agent] The lubricating oil composition of one embodiment of the present invention may further contain an antifoaming agent. The antifoaming agents 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 silicone oil, fluorosilicone oil, and fluoroalkyl ether.

[0085] <Method of manufacturing 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 preferable to have a step of blending component (A) with components (B) and (C), and, if necessary, component (D) and the various additives described above other than components (B) to (D). The preferred compounds and amounts of the components (A) to (D) and various additives are as described above.

[0086] [Properties of lubricating oil composition] The kinematic viscosity at 100°C of the lubricating oil composition of one embodiment of the present invention is preferably 2.1 mmHg, from the viewpoint of further improving the insulating properties, increasing the flash point, and providing a lubricating oil composition with excellent handleability. 2 / s or more, preferably 2.2 mm 2 / s or more, preferably 2.4 mm 2 / s or more, more preferably 2.5 mm 2 / s or more, and even more preferably 2.7 mm 2 / s or more, particularly preferably 2.8 mm 2 / s or more, and from the viewpoint of providing a lubricating oil composition with excellent cooling properties, it is preferably 5.0 mm 2 / s, preferably less than 4.8 mm 2 / s or less, preferably 4.5 mm 2 / s or less, preferably 4.2 mm 2 / s or less, more preferably 4.1 mm 2 / s or less, more preferably 3.9 mm 2 / s or less, and even more preferably 3.7 mm 2 / s or less, and even more preferably 3.5 mm 2 / s or less, particularly preferably 3.2 mm 2 / s or less, and further, 3.0 mm 2 / s or less, 2.8mm 2 / s or less, or 2.6 mm 2 / s or less may be used.

[0087] The viscosity index of the lubricating oil composition of one embodiment of the present invention is preferably 80 or greater, more preferably 90 or greater, even more preferably 100 or greater, still more preferably 110 or greater, and particularly preferably 117 or greater.

[0088] For the lubricating oil composition of one embodiment of the present invention, the load stage at which scuffing occurs, measured in accordance with ASTM D5182 under the conditions described in the Examples below, is preferably 5 or higher, more preferably 6 or higher, even more preferably 7 or higher, and still more preferably 8 or higher.

[0089] When the ISOT test conforming to JIS K2514 is carried out for 72 hours at 150°C using copper flakes as a catalyst as described in the Examples below, the amount of copper eluted from the lubricating oil composition of one embodiment of the present invention is preferably less than 15 ppm by mass, more preferably 14 ppm by mass or less, even more preferably 13 ppm by mass or less, still more preferably 12 ppm by mass or less, and particularly preferably 11 ppm by mass or less. In this specification, the amount of copper elution means a value measured in accordance with JPI-5S-38-92.

[0090] For a lubricating oil composition according to one embodiment of the present invention, when an oxidation stability test in accordance with CEC L-48-A-00(B) is carried out at a temperature of 160°C for 192 hours as described in the Examples below, the increase in kinematic viscosity at 100°C before and after the test is preferably less than 12%, more preferably 10% or less, more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, still more preferably 6% or less, and particularly preferably 5% or less. The 100°C kinematic viscosity increase rate is a value calculated from the following formula, and the kinematic viscosity is a value measured in accordance with JIS K2283:2000. · [100°C kinematic viscosity thickening rate (%)] = ([100°C kinematic viscosity of the lubricating oil composition after the test (mm 2 / s)]-[100°C kinematic viscosity of the lubricating oil composition before the test (mm 2 / s)]) / [100°C kinematic viscosity of the lubricating oil composition before the test (mm 2 / s)] × 100

[0091] The lubricating oil composition according to one embodiment of the present invention preferably has a volume resistivity of 1.7×10, measured in accordance with JIS C2101 under the conditions described in the Examples below. 7 Ω·m or more, preferably 1.9×10 7 Ω·m or more, preferably 2.0×10 7 Ω·m or more, more preferably 2.2×10 7 Ω·m or more, more preferably 2.3×10 7 Ω·m or more, and even more preferably 2.5×10 7 Ω·m or more, particularly preferably 2.7×10 7 Ω·m or more, and is usually 1.0×10 9 Ω·m or less.

[0092] [Uses of lubricating oil composition] The lubricating oil composition of a preferred embodiment of the present invention can improve properties such as scuffing resistance, copper elution suppression effect, oxidation stability, and insulating properties in a well-balanced manner. In particular, the lubricating oil composition of a preferred embodiment of the present invention can maintain these properties well even when the viscosity is reduced, and therefore is also excellent in terms of cooling properties. Considering these properties, the lubricating oil composition of one embodiment of the present invention can be suitably used for lubricating mechanisms such as torque converters, wet clutches, gear bearing mechanisms, oil pumps, and hydraulic control mechanisms that are incorporated into various devices such as engines, transmissions, reducers, compressors, and hydraulic devices. Of these, the lubricating oil composition of one embodiment of the present invention is preferably used for lubricating reducers.

[0093] Furthermore, in consideration of the above-mentioned properties of the lubricating oil composition of one embodiment of the present invention, the present invention can also provide the following [1] and [2]. [1] A lubricating oil composition comprising a base oil (A), a thiadiazole compound (B), and a boron-modified alkenyl succinimide (C), wherein the content of component (B) is less than 0.60 mass% based on the total amount of the lubricating oil composition, the content ratio [B / N] of boron atoms and nitrogen atoms derived from component (C) is 0.35 or more by mass, and the content of boron atoms derived from component (C) is 300 mass ppm or less based on the total amount of the lubricating oil composition. A reducer using a lubricating oil composition. [2] A lubricating oil composition comprising a base oil (A), a thiadiazole compound (B), and a boron-modified alkenyl succinimide (C), wherein the content of component (B) is less than 0.60 mass% based on the total amount of the lubricating oil composition, the content ratio [B / N] of boron atoms and nitrogen atoms derived from component (C) is 0.35 or more by mass, and the content of boron atoms derived from component (C) is 300 mass ppm or less based on the total amount of the lubricating oil composition. Use of a lubricating oil composition, wherein the lubricating oil composition is applied to lubricate a reducer. The preferred embodiments of the lubricating oil compositions described in [1] and [2] above are as described above. [Example]

[0094] 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.

[0095] (1)Kinematic viscosity, viscosity index Measurements and calculations were made in accordance with JIS K2283:2000. (2) Boron atom and phosphorus atom content Measurements were performed in accordance with JPI-5S-38-92. (3) Nitrogen atom content Measurements were made in accordance with JIS K2609. (4) Sulfur atom content Measurements were performed in accordance with JIS K2541-6:2013.

[0096] Examples 1 to 4, Comparative Examples 1 to 4 Lubricating oil compositions were prepared by adding and mixing the types of base oils and various additives shown in Table 1 in the amounts shown in Table 1. Details of the components used in preparing the lubricating oil compositions are as follows. Note that the molybdenum atom content in each lubricating oil composition was less than 2 ppm by mass.

[0097] <Component (A): Base oil> "Mineral oil (1)": 60N hydrocracked mineral oil, kinematic viscosity at 100°C = 2.2 mm 2 / s, viscosity index=108. "Mineral oil (2)": 100N hydrocracked mineral oil, kinematic viscosity at 100°C = 4.2 mm 2 / s, viscosity index=122.

[0098] <Component (B): Thiadiazole-based compound> "Thiadiazole (branched chain)": 2,5-bis(1,1-dimethylheptyldithio)-1,3,4-thiadiazole, in the general formula (b-1), m=n=2, R 1 and R 2 Thiadiazole in which the group is a 1,1-dimethylheptyl group. Sulfur atom content = 33.3 mass%, nitrogen atom content = 6.4 mass%.

[0099] <Component (C): Boron-modified alkenyl succinimide> "B-modified polybutenyl succinic acid bisimide (1)": A boron-modified polybutenyl succinic acid bisimide having polybutenyl groups. "B-modified polybutenyl succinic acid bisimide (2)": A boron-modified polybutenyl succinic acid bisimide having polybutenyl groups. "B-modified polybutenyl succinic acid bisimide (3)": A boron-modified polybutenyl succinic acid bisimide having polybutenyl groups. "B-modified polybutenyl succinic acid bisimide (4)": A boron-modified polybutenyl succinic acid bisimide having polybutenyl groups.

[0100] <Component (D): Phosphorus-based compound> "Sulfur-phosphorus compound": a compound in which a1=2, R A11 a sulfur atom-containing phosphite ester in which a2 = a3 = 2, R = n-octyl group, and A21 , R A22 = Mixture of sulfur atom-containing phosphite ester with n-octyl group. Phosphorus atom content = 10 mass %, sulfur atom content = 10.7 mass %.

[0101] <Ashless dispersant> "Unmodified polybutenyl succinic acid bisimide": Polybutenyl succinic acid bisimide having polybutenyl groups. <Other additives> · "Additive Blend": A blend of pour point depressants, antioxidants, metal detergents, dispersants, metal deactivators, friction modifiers, and antifoam agents.

[0102] The kinematic viscosity and viscosity index of the prepared lubricating oil compositions were measured and calculated, and the following tests were also carried out. The results are shown in Tables 1 and 2.

[0103] (1) FZG scuffing test (A10 / 16.6R / 90) In accordance with ASTM D5182, an A10 type gear was used, and the load was increased stepwise in accordance with the regulations under the conditions of a sample oil temperature of 90°C, a rotation speed of 2900 rpm, and an operating time of approximately 7.5 minutes, and the load stage at which scuffing occurred was determined. The higher the stage value, the better the lubricating oil composition's gear scuffing resistance.

[0104] (2) Copper elution test The ISOT test conforming to JIS K2514 was carried out using copper and iron pieces as catalysts at a temperature of 150°C for 72 hours to degrade the sample oil. The amount of copper eluted from the aged sample oil (unit: ppm by mass) was measured using a method conforming to JPI-5S-38-92. The lower the value of the copper elution amount, the more effective the lubricating oil composition in inhibiting copper elution.

[0105] (3) Oxidation stability test An oxidation stability test was conducted in accordance with CEC L-48-A-00(B) at 160°C for 192 hours. After the test, the 100°C kinematic viscosity of the lubricating oil composition was measured in accordance with JIS K2283:2000, and the 100°C kinematic viscosity thickening rate was calculated using the following formula: · [100°C kinematic viscosity thickening rate (%)] = ([100°C kinematic viscosity of the lubricating oil composition after the test (mm 2 / s)]-[100°C kinematic viscosity of the lubricating oil composition before the test (mm 2 / s)]) / [100°C kinematic viscosity of the lubricating oil composition before the test (mm 2 / s)] × 100

[0106] (4) Insulation test The volume resistivity of the sample oil was measured in accordance with JIS C2101 under test conditions of a measurement temperature of 80°C, an applied voltage of 250 V, and a measurement time of 1 minute. The higher the volume resistivity value, the more excellent the insulating properties of the lubricating oil composition.

[0107] [Table 1]

[0108] [Table 2]

[0109] As can be seen from Table 1, the lubricating oil compositions of Examples 1 to 13 exhibited excellent results in terms of well-balanced properties of anti-scuffing properties, copper elution inhibiting effect, oxidation stability, and insulating properties. On the other hand, as can be seen from Table 2, the lubricating oil composition of Comparative Example 1 had poor oxidation stability, and the lubricating oil compositions of Comparative Examples 2 to 3 and 6 to 7 had poor copper elution suppression effects. Furthermore, the lubricating oil compositions of Comparative Examples 4 and 5 had poor scuffing resistance and insulating properties.

Claims

1. A lubricating oil composition comprising a base oil (A), a thiadiazole compound (B), and a boron-modified alkenyl succinimide (C), Component (B) contains a thiadiazole-based compound (B1) having a branched alkyl group, The content of component (B) is less than 0.60 mass% based on the total amount of the lubricating oil composition, The component (C) contains a boron-modified alkenyl succinic acid bisimide (C1), the content ratio [B / N] of boron atoms and nitrogen atoms derived from component (C) is 0.35 or more in mass ratio; the content of boron atoms derived from component (C) is 300 ppm by mass or less based on the total amount of the lubricating oil composition; The composition further contains one or more phosphorus-based compounds (D) selected from phosphate esters and phosphites, and the component (D) contains one or more sulfur-phosphorus compounds (D1) selected from sulfur-containing phosphate esters and sulfur-containing phosphites. Lubricating oil composition.

2. 2. The lubricating oil composition according to claim 1, wherein the content of nitrogen atoms derived from component (C) is 320 ppm by mass or less based on the total amount of the lubricating oil composition.

3. 3. The lubricating oil composition according to claim 1, wherein the content of nitrogen atoms derived from component (C) is 5.0 to 320 ppm by mass based on the total amount of the lubricating oil composition.

4. The lubricating oil composition according to any one of claims 1 to 3, wherein the content ratio [B / N] of boron atoms to nitrogen atoms derived from component (C) is 0.35 to 2.0 in mass ratio.

5. The lubricating oil composition according to any one of claims 1 to 4, wherein the content of boron atoms derived from component (C) is 3.0 to 300 ppm by mass, based on the total amount of the lubricating oil composition.

6. 6. The lubricating oil composition according to any one of claims 1 to 5, wherein the content of sulfurized olefin is less than 0.20 mass % based on the total amount of the lubricating oil composition.

7. The lubricating oil composition has a kinematic viscosity of 2.1 mm at 100°C. ２ / s or more 5.0mm ２ The lubricating oil composition according to any one of claims 1 to 6, wherein the viscosity is less than 1000 kJ / s.

8. The lubricating oil composition according to any one of claims 1 to 7, wherein the content ratio [B / N] of boron atoms and nitrogen atoms derived from component (C) is 0.60 or more in mass ratio.

9. The lubricating oil composition according to any one of claims 1 to 8, wherein the content of boron atoms derived from component (C) is 150 ppm by mass or less, based on the total amount of the lubricating oil composition.

10. The lubricating oil composition according to any one of claims 1 to 9, which is used to lubricate a reducer.

11. A reducer to which the lubricating oil composition according to any one of claims 1 to 10 is applied.

12. Use of the lubricating oil composition according to any one of claims 1 to 10 for lubricating a reducer.

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