Lubricating oil composition

Abstract

The present invention provides a lubricating oil composition that, while having low viscosity, improves extreme pressure resistance, wear resistance, and fatigue resistance, which tend to deteriorate with lower viscosity lubricants, while suppressing a decrease in oxidation stability and satisfying the wet clutch performance required for transmissions. [Solution] A lubricating oil base oil comprising a mineral oil-based base oil and / or a synthetic base oil, (A) a thiadiazole compound, (B) a phosphorus compound, (C) a calcium-based detergent, (D) a succinimide dispersant containing a boron-containing succinimide dispersant, and (E) an oily friction modifier, wherein the sulfur content is 0.050% by mass or less, the boron content is less than 0.030% by mass, and the kinematic viscosity at 100°C is 6.2 mm. 2 A lubricating oil composition having a volume of 0.0 / s or less, a mass ratio of sulfur content MS to phosphorus content MP MS / MP of 1.00 or less, and a mass ratio of boron content MB to calcium content MCa MB / MCa of 0.80 to 1.20.

Description

[Technical Field]

[0001] The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition that can be suitably used for lubricating a transmission having a wet clutch, such as a wet multi-plate clutch, and especially an automatic transmission having a wet clutch or a continuously variable transmission having a wet clutch. [Background technology]

[0002] One way to conserve energy in gear systems such as transmissions and final drive units is to reduce the viscosity of the lubricating oil. For example, transmissions and final drive units have gear bearing mechanisms, and by reducing the viscosity of the lubricating oil used in them, the stirring resistance and drag torque caused by the viscous resistance of the lubricating oil are reduced, which is thought to improve power transmission efficiency and, as a result, improve fuel efficiency. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-196396 [Patent Document 2] International Publication No. 2014 / 142231 [Patent Document 3] Special Publication No. 2021-515061 [Patent Document 4] Special Publication No. 2020-531618 [Patent Document 5] Japanese Patent Publication No. 2021-147521 [Patent Document 6] Japanese Patent Publication No. 2021-147517 [Patent Document 7] Japanese Patent Publication No. 2020-111736 [Patent Document 8] Japanese Patent Publication No. 2011-132551 [Patent Document 9] Patent No. 4822684 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Generally, reducing the viscosity of lubricating oil improves fuel efficiency, but it tends to decrease lubrication performance such as extreme pressure resistance, wear resistance, and fatigue resistance due to the reduction in oil film thickness. To compensate for or improve these performance aspects that decrease with lower viscosity lubricating oil, one option is to add or increase the content of additives that function as extreme pressure agents and / or wear inhibitors, such as sulfur-based additives, phosphorus-based additives, and phosphorus-sulfur-based additives. However, adding or increasing these additives creates new problems, such as worsening the oxidation stability of the lubricating oil and degrading the friction characteristics of wet clutches. Therefore, there remains a demand for solutions to the problems associated with lower viscosity lubricating oil.

[0005] The present invention aims to provide a lubricating oil composition that, while having low viscosity, improves extreme pressure properties, wear resistance, and fatigue resistance, which tend to deteriorate with lower viscosity lubricating oils, and also satisfies the wet clutch performance required for transmissions while suppressing a decrease in oxidation stability. [Means for solving the problem]

[0006] The present invention encompasses the following embodiments [1] to

[11] . [1] A lubricating oil base oil comprising one or more mineral oil-based base oils, one or more synthetic base oils, or a combination thereof, (A) One or more thiadiazole compounds, (B) One or more phosphorus compounds, (C) One or more calcium-based cleaning agents, (D) One or more succinimide dispersants containing one or more boron-containing succinimide dispersants, (E) One or more oil-based friction modifiers, It contains, The sulfur content in the composition is 0.050% by mass or less based on the total amount of the composition. The boron content in the composition is less than 0.030% by mass on a basis of the total composition. The kinematic viscosity of the composition at 100°C is 6.2 mm². 2 It is less than or equal to / s, The ratio MS / MP of the sulfur content MS (unit: mass%) in the composition to the phosphorus content MP (unit: mass%) in the composition is 1.00 or less. A lubricating oil composition characterized in that the ratio MB / MCa of the boron content in the composition to the calcium content in the composition (MCa, mass%) is 0.80 to 1.20.

[0007] [2] The lubricating oil composition according to [1], wherein the content of component (A) is 0.010 to 0.050% by mass as sulfur content on a basis of the total composition.

[0008] [3] The lubricating oil composition according to [1] or [2], wherein the content of component (B) is 0.010 to 0.100% by mass as phosphorus on a basis of the total composition.

[0009] [4] The lubricating oil composition according to any one of [1] to [3], wherein the boron content MB in the composition is 0.010% by mass or more and less than 0.030% by mass on a basis of the total amount of the composition.

[0010] [5] The lubricating oil composition according to any one of [1] to [4], wherein the content of component (C) is 0.008 to 0.040% by mass as calcium on a basis of the total composition.

[0011] [6] The lubricating oil composition according to any one of [1] to [5], wherein the content of component (D) is 0.010% by mass or more and less than 0.030% by mass as boron content on a basis of the total composition.

[0012] [7] The lubricating oil composition according to any one of [1] to [6], wherein the component (E) contains 0.10 to 3.00% by mass of one or more N-acylated nitrogen-containing compounds, based on the total amount of the composition, wherein component (E1) has one or more aliphatic hydrocarbyl groups having 8 to 30 carbon atoms and / or one or more aliphatic hydrocarbyl carbonyl groups having 8 to 30 carbon atoms and one or more amide bonds and / or one or more imide bonds in one molecule, and the aliphatic hydrocarbyl carbonyl groups may constitute part of the amide bonds and / or imide bonds.

[0013] [8] (F) A lubricating oil composition according to any one of [1] to [7], further comprising one or more poly(meth)acrylates having a weight-average molecular weight of 10,000 to 100,000.

[0014] [9] (G) A lubricating oil composition according to any one of [1] to [8], containing 0.10 to 1.00% by mass of one or more amine-based antioxidants and / or one or more phenol-based antioxidants based on the total amount of the composition.

[0015]

[10] The kinematic viscosity of the lubricating oil base oil at 100°C is 4.2 mm 2 A lubricating oil composition according to any one of [1] to [9], wherein the viscosity index is 120 or higher and the viscosity index is 1 / s or higher.

[0016]

[11] The lubricating oil composition according to any one of [1] to

[10] , wherein the viscosity index of the lubricating oil composition is 155 or higher.

[0017]

[12] A lubricating oil shear stability test in accordance with JPI-5S-29-88 showed that the kinematic viscosity of the lubricating oil composition at 100°C after irradiating it with ultrasonic waves at a frequency of 10 kHz and a transducer amplitude of 28 μm for 10 hours was 5.5 mm². 2 A lubricating oil composition according to any of [1] to

[11] , wherein the value is / s or greater.

[0018]

[13] A lubricating oil composition according to any one of [1] to

[12] , used for lubricating a transmission equipped with a wet clutch. [Effects of the Invention]

[0019] According to the present invention, there is provided a lubricating oil composition which, while having a low viscosity, improves extreme pressure properties, anti-wear properties, and fatigue resistance, which tend to deteriorate with the reduction of the viscosity of the lubricating oil, and satisfies the wet clutch performance required for a transmission while suppressing a decrease in oxidation stability.

Mode for Carrying Out the Invention

[0020] Hereinafter, the present invention will be described in detail. In this specification, unless otherwise specified, the notation "A to B" for numerical values A and B is equivalent to "A or more and B or less". In such a notation, when a unit is attached only to numerical value B, the unit is also applied to numerical value A. In this specification, the words "or" and "or" mean logical disjunction unless otherwise specified. In this specification, the notation "E1 and / or E2" for elements E1 and E2 is equivalent to "E1, or E2, or a combination thereof", and for N elements E1,..., E i ,..., E N (where N is an integer of 3 or more) the notation "E1,..., and / or E N " is equivalent to "E1,..., or E i ,..., or E N (where i is a variable taking values of all integers satisfying 1 < i < N). Also, in this specification, "alkaline earth metal" includes magnesium.

[0021] In this specification, unless otherwise specified, the content of calcium, magnesium, zinc, phosphorus, sulfur, boron, barium, and molybdenum in oil shall be measured by inductively coupled plasma atomic emission spectrometry (intensity ratio method (internal standard method)) in accordance with JIS K0116. The content of nitrogen in oil shall be measured by chemiluminescence in accordance with JIS K2609. In this specification, "weight-average molecular weight" refers to the weight-average molecular weight on a standard polystyrene basis, measured by gel permeation chromatography (GPC). The measurement conditions for GPC are as follows. [GPC measurement conditions] Equipment: Waters Corporation ACQUITY® APC UV RI system Columns: Two Waters Corporation ACQUITY® APC XT900A columns (gel particle size 2.5 μm, column size (inner diameter x length) 4.6 mm x 150 mm) and one Waters Corporation ACQUITY® APC XT200A column (gel particle size 2.5 μm, column size (inner diameter x length) 4.6 mm x 150 mm) are connected in series from upstream to downstream. Column temperature: 40℃ Sample solution: 1.0% by mass tetrahydrofuran solution of the sample. Eluent: Tetrahydrofuran Solution injection volume: 20.0μL Detection device: Differential refractive index detector Reference material: Standard polystyrene (Agilent EasiCal® PS-1, manufactured by Agilent Technologies) 8 points (molecular weight: 2,698,000, 597,500, 290,300, 133,500, 70,500, 30,230, 95,90, 2970) If the weight-average molecular weight measured under the above conditions is less than 10,000, the column and reference material will be changed to the following conditions and the measurement will be repeated. Columns: From upstream to downstream, one Waters Corporation ACQUITY® APC XT125A (gel particle size 2.5 μm, column size (inner diameter x length) 4.6 mm x 150 mm) and two Waters Corporation ACQUITY® APC XT45A (gel particle size 1.7 μm, column size (inner diameter x length) 4.6 mm x 150 mm) are connected in series. Reference material: Standard polystyrene (Agilent EasiCal® PS-1, manufactured by Agilent Technologies) 10 samples (molecular weight: 30230, 9590, 2970, 890, 786, 682, 578, 474, 370, 266)

[0022] <Lubricant base oil> The lubricating oil composition of the present invention (hereinafter sometimes referred to as "lubricating oil composition" or "composition") comprises a main amount of lubricating oil base oil and one or more additives other than the base oil. In the lubricating oil composition of the present invention, the lubricating oil base oil used is a lubricating oil base oil comprising one or more mineral oil-based base oils, one or more synthetic base oils, or a combination thereof.

[0023] As the lubricating oil base oil, one or more mineral oil-based base oils, one or more synthetic base oils, or a mixture thereof can be used. In one embodiment, as the lubricating oil base oil, a Group I base oil (hereinafter sometimes referred to as "API Group I base oil"), a Group II base oil (hereinafter sometimes referred to as "API Group II base oil"), a Group III base oil (hereinafter sometimes referred to as "API Group III base oil"), a Group IV base oil (hereinafter sometimes referred to as "API Group IV base oil"), or a Group V base oil (hereinafter sometimes referred to as "API Group V base oil") of the API base oil classification can be used. API Group I base oil is a mineral oil-based base oil having a sulfur content of more than 0.03% by mass and / or a saturation content of less than 90% by mass, and a viscosity index of 80 or more and less than 120. API Group II base oil is a mineral oil-based base oil having a sulfur content of 0.03% by mass or less, a saturation content of 90% by mass or more, and a viscosity index of 80 or more and less than 120. API Group III base oils are mineral oil-based base oils with a sulfur content of 0.03% by mass or less, a saturation content of 90% by mass or more, and a viscosity index of 120 or higher. API Group IV base oils are poly-α-olefin base oils. API Group V base oils are base oils other than those in Groups I to IV, and a preferred example of such a base oil is an ester-based base oil.

[0024] In one embodiment, component (A) may preferably be one or more API group II base oils, one or more API group III base oils, one or more API group IV base oils, or one or more API group V base oils, or a combination thereof.

[0025] Examples of mineral oil-based base oils include paraffinic base oils obtained by subjecting lubricating oil fractions obtained by atmospheric distillation and / or vacuum distillation of crude oil to one or more combinations selected from purification processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment, and normal paraffinic base oils, isoparaffinic base oils, and mixtures thereof. API Group II base oils and Group III base oils are usually produced through a hydrocracking process.

[0026] %C of mineral oil-based base oil P is preferably 60 or more, more preferably 65 or more, from the viewpoint of further enhancing the viscosity-temperature characteristics and fuel economy of the composition, and is preferably 99 or less, more preferably 95 or less, even more preferably 94 or less, from the viewpoint of enhancing the solubility of additives, and can be 60 - 99, or 60 - 95, or 65 - 95, or 65 - 94 in one embodiment.

[0027] %C of mineral oil-based base oil A is preferably 2 or less, more preferably 1 or less, even more preferably 0.8 or less, particularly preferably 0.5 or less, from the viewpoint of further enhancing the viscosity-temperature characteristics and fuel economy of the composition.

[0028] %C of mineral oil-based base oil N is preferably 1 or more, more preferably 4 or more, from the viewpoint of enhancing the solubility of additives, and is preferably 40 or less, more preferably 35 or less, from the viewpoint of further enhancing the viscosity-temperature characteristics and fuel economy of the composition, and can be 1 - 40, or 4 - 35 in one embodiment.

[0029] In this specification, %C P , %C N and %C A respectively mean the percentages of paraffinic carbon number, naphthenic carbon number, and aromatic carbon number with respect to the total carbon number, determined by the method (n-d-M ring analysis) in accordance with ASTM D 3238-85. That is, the above-mentioned %C P, %C N and %C A The preferred range is based on the value obtained by the above method, and even for lubricating oil base oils that do not contain naphthenes, the %C obtained by the above method is also applicable. N This can represent a value greater than 0.

[0030] From the viewpoint of improving the viscosity-temperature characteristics of the composition, the saturation content in the mineral oil-based base oil is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more, based on the total amount of base oil. In this specification, saturation content refers to the value measured in accordance with ASTM D 2007-93.

[0031] The aromatic content in the mineral oil-based base oil is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, and particularly preferably 0 to 1% by mass, based on the total amount of base oil, and in one embodiment it may be 0.1% by mass or more. By keeping the aromatic content below the above upper limit, it is possible to improve the low-temperature viscosity characteristics and viscosity-temperature characteristics in the new oil state, further improve fuel efficiency, and reduce the amount of lubricant consumed by reducing evaporation loss of the lubricant. In addition, when additives are blended into the lubricant base oil, it becomes possible to effectively exert the effects of the additives. Furthermore, the lubricant base oil may not contain aromatics, but by keeping the aromatic content above the above lower limit, the solubility of the additives can be improved.

[0032] In this specification, the term "aromatic content" refers to values ​​measured in accordance with ASTM D 2007-93. Aromatic content typically includes alkylbenzenes, alkylnaphthalenes, anthracenes, phenanthrenes and their alkylates, as well as compounds in which four or more benzene rings are fused, pyridines, quinolines, phenols, naphthols, and other aromatic compounds containing heteroatoms.

[0033] Examples of API Group IV base oils include oligomers and co-oligomers of α-olefins having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms, such as ethylene-propylene copolymers, polybutene, 1-octene oligomers, 1-decene oligomers, and their hydrogenation products, as well as their hydrogenation products.

[0034] Preferred examples of API Group V base oils include ester-based base oils such as monoesters (e.g., butyl stearate, octyl laurate, 2-ethylhexyl oleate, etc.); diesters (e.g., ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, etc.); polyesters (e.g., trimellitic acid esters, etc.); and polyol esters (e.g., trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, etc.). Other examples of API Group V base oils include aromatic synthetic base oils such as alkylbenzenes, alkylnaphthalenes, polyoxyalkylene glycols, dialkyldiphenyl ethers, and polyphenyl ethers.

[0035] The kinematic viscosity of the lubricating oil base oil (whole base oil) at 40°C is preferably 40 mm², from the viewpoint of energy saving and improving the low-temperature viscosity characteristics of the lubricating oil composition. 2 / s or less, or 30mm 2 / s or less, or 22mm 2 It is less than or equal to / s. In this specification, "kinematic viscosity at 40°C" means the kinematic viscosity at 40°C measured in accordance with JIS K 2283-2000 using an automatic viscometer (product name "CAV-2100", manufactured by Cannon Instruments).

[0036] The kinematic viscosity of the lubricating oil base oil (whole base oil) at 100°C is preferably 6.0 mm from the viewpoint of further improving energy efficiency and the low-temperature viscosity characteristics of the lubricating oil composition. 2 / s or less, or 5.5mm 2 / s or less, or 5.0mm 2 The length should be less than or equal to / s, and preferably 3.5 mm from the viewpoint of improving wear resistance and seizure resistance. 2 / s or more, or 4.0mm 2 / s or more, or 4.2mm 2 It is 1 / s or more, and in one embodiment it is 3.5 to 6.0 mm 2 / s, or 4.0~5.5mm 2 / s, or 4.0~5.0mm 2 / s, or 4.2-5.0 mm 2 It may be / s. In this specification, "kinematic viscosity at 100°C" means the kinematic viscosity at 100°C measured in accordance with JIS K 2283-2000 using an automatic viscometer (product name "CAV-2100", manufactured by Cannon Instruments).

[0037] The viscosity index of the lubricating oil base oil (whole base oil) is preferably 100 or higher, more preferably 105 or higher, even more preferably 110 or higher, particularly preferably 115 or higher, and most preferably 120 or higher, from the viewpoint of improving the viscosity-temperature characteristics of the composition, as well as further improving fuel efficiency and wear resistance. In this specification, the viscosity index refers to the viscosity index measured using an automatic viscometer (product name "CAV-2100", manufactured by Cannon Instruments) as the measuring device, in accordance with JIS K 2283-2000.

[0038] The pour point of the lubricating oil base oil (whole base oil) is preferably -10°C or lower, more preferably -12.5°C or lower, even more preferably -15°C or lower, particularly preferably -17.5°C or lower, and most preferably -20.0°C or lower, from the viewpoint of the low-temperature fluidity of the entire lubricating oil composition. In this specification, the pour point refers to the pour point measured in accordance with JIS K 2269-1987.

[0039] The sulfur content in the base oil depends on the sulfur content of its raw materials. For example, when using substantially sulfur-free raw materials such as synthetic wax components obtained by the Fischer-Tropsch reaction, a substantially sulfur-free base oil can be obtained. On the other hand, when using sulfur-containing raw materials such as slack wax obtained in the base oil refining process or microwax obtained in the refining process, the sulfur content in the resulting base oil is usually 100 ppm by mass or more. The sulfur content in lubricating oil base oil (total base oil) is usually 0.03% by mass or less, and preferably 0.01% by mass or less from the viewpoint of oxidation stability. In this specification, the sulfur content in the base oil refers to the amount of sulfur measured in accordance with JIS K 2541-2003.

[0040] In one embodiment, the lubricating oil base oil may contain 80-100% by mass, 90-100% by mass, 95-100% by mass, or 98-100% by mass, or 98-100% by mass, based on the total amount of base oil, of one or more API Group II base oils, one or more API Group III base oils, one or more API Group IV base oils, or one or more API Group V base oils, or a combination thereof. The lubricating oil base oil may or may not contain API group V base oils, but the content of one or more API group V base oils in the lubricating oil base oil is preferably 0 to 50% by mass, 0 to 20% by mass, or 0 to 10% by mass based on the total amount of base oil, from the viewpoint of enhancing oxidation stability in one embodiment.

[0041] The content of lubricating oil base oil (whole base oil) in the lubricating oil composition is usually 60% by mass or more on a basis of the total amount of the lubricating oil composition, and in one embodiment it may be 85-98.5% by mass, 90-98.5% by mass, or 93-97% by mass.

[0042] <(A) Thiadiazole compounds> The lubricating oil composition of the present invention contains (A) one or more thiadiazole compounds (hereinafter sometimes referred to as "component (A)"). Component (A) may be one thiadiazole compound used alone, or two or more thiadiazole compounds may be used in combination.

[0043] Examples of component (A) include 1,3,4-thiadiazole represented by the following general formula (1), 1,2,4-thiadiazole compounds represented by the following general formula (2), and 1,2,3-thiadiazole compounds represented by the following general formula (3).

[0044] [ka]

[0045] [ka]

[0046] [ka] (In general formulas (1) to (3), R 1 and R 2 a and b may be the same or different, and each independently represents a hydrogen atom or a hydrocarbyl (preferably alkyl) group having 1 to 20 carbon atoms (preferably 6 to 18, or 9 to 12, e.g., 9); a and b may be the same or different, and each independently represents an integer from 0 to 8.

[0047] (A) The component is represented by any of the above general formulas (1) to (3), where a and b are 2, and R 1 and R 2Bis(alkyldithio)thiadiazole compounds in which each of the alkyl groups has 6 to 18 carbon atoms can be used particularly preferably. In one embodiment, the number of carbon atoms in the alkyl group may be 9 to 12 or 9. In one embodiment, such a bis(alkyldithio)thiadiazole compound may be used in combination with a mono(alkyldithio)thiadiazole compound. The mono(alkyldithio)thiadiazole compound is represented by any of the general formulas (1) to (3) and -S a -R 1 Base and -S b -R 2 A mono(alkyldithio)thiadiazole compound is preferred in which one of the groups is an alkyldithio group having 6 to 18 carbon atoms, and the other is an -SSH group or an -SH group. The preferred number of carbon atoms for the alkyl group is the same as for bis(alkyldithio)thiadiazole compounds.

[0048] The content of component (A) in the lubricating oil composition is 0.050% by mass or less, preferably 0.045% by mass or less, or 0.040% by mass or less, as sulfur content on a basis of the total composition, from the viewpoint of improving the transmission torque capacity and fastening performance of the wet clutch and improving the wear resistance of the gears. Furthermore, the content of component (A) is preferably 0.010% by mass or more, as sulfur content on a basis of the total composition, from the viewpoint of further improving the wear resistance, fatigue resistance of the gears, and oxidation stability of the lubricating oil, as well as further improving the transmission torque capacity and fastening performance of the wet clutch. In one embodiment, the content of component (A) may be 0.010 to 0.050% by mass, or 0.010 to 0.045% by mass, or 0.010 to 0.040% by mass, as sulfur content on a basis of the total composition.

[0049] <(B) Sulfur-free phosphorus compounds> The lubricating oil composition of the present invention contains (B) one or more sulfur-free phosphorus compounds (hereinafter sometimes referred to as "component (B)"). Component (B) may be a single phosphorus compound or a combination of two or more phosphorus compounds.

[0050] (B) Preferred examples of component (B) include compounds represented by the following general formula (4), compounds represented by the following general formula (5), and metal salts and ammonium salts of phosphite monoesters represented by the following general formula (4) and phosphate partial esters represented by the following general formula (5).

[0051] [ka] (In general formula (4), R 3 R represents a hydrocarbon group with 1 to 30 carbon atoms; 4 R represents a hydrocarbon group or hydrogen atom with 1 to 30 carbon atoms; 3 and R 4 These elements may be identical or mutually distinct. The compound of general formula (4) encompasses any of its tautomers.

[0052] [ka] (In general formula (5), R 5 R represents a hydrocarbon group with 1 to 30 carbon atoms; 6 and R 7 Each of these independently represents a hydrocarbon group or hydrogen atom having 1 to 30 carbon atoms; R 5 , R 6 , and R 7 They may be the same or they may be different from one another.

[0053] Examples of hydrocarbon groups having 1 to 30 carbon atoms in general formulas (4) and (5) include alkyl groups, cycloalkyl groups, alkenyl groups, alkyl-substituted cycloalkyl groups, aryl groups, alkyl-substituted aryl groups, and arylalkyl groups. The hydrocarbon group is preferably an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 24 carbon atoms, and in one embodiment, it is an alkyl group, aryl group, or alkylaryl group having 3 to 18 carbon atoms, more preferably 4 to 12 carbon atoms.

[0054] In one embodiment, preferred examples of hydrocarbon groups include linear or branched alkyl groups having 4 to 18 carbon atoms. Examples of alkyl groups include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. Other preferred examples of hydrocarbon groups include aryl groups having 6 to 10 carbon atoms, such as phenyl and naphthyl groups; and alkylaryl groups having 7 to 9 carbon atoms, such as tolyl, xylyl, and mesityl groups.

[0055] Examples of metals that form metal salts with phosphorus compounds represented by general formula (4) or (5) include alkali metals such as lithium, sodium, potassium, and cesium; alkaline earth metals such as calcium, magnesium, and barium; and heavy metals such as zinc, copper, iron, lead, nickel, silver, and manganese. Among these, alkaline earth metals such as calcium and magnesium, or zinc, or combinations thereof are preferred.

[0056] Examples of nitrogen-containing compounds that form ammonium salts with phosphorus compounds represented by general formula (4) or (5) include ammonia, monoamines, diamines, polyamines, and alkanolamines. More specifically, examples include nitrogen-containing compounds represented by the following general formula (6); alkylenediamines such as methylenediamine, ethylenediamine, propylenediamine, and butylenediamine; polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine; and combinations thereof.

[0057] [ka] (In general formula (6), R 8 ~R 10Each of these independently represents a hydrogen atom, a C1-C8 hydrocarbyl group, or a C1-C8 hydrocarbyl group having a hydroxyl group; R 8 ~R 10 At least one of these is a hydroxyl group having 1 to 8 carbon atoms, or a hydroxyl group having 1 to 8 carbon atoms.

[0058] A preferred example of a compound represented by the above general formula (4) is one in which R 3 and R 4 Examples of diphosphorite ester compounds include those in which each is independently an alkyl group, aryl group (e.g., phenyl group, naphthyl group, etc.), or alkylaryl group (e.g., methylphenyl group, dimethylphenyl group, trimethylphenyl group (e.g., mesityl group, etc.), isopropylphenyl group, isopropylmethylphenyl group (e.g., thymyl group, etc.), and other alkylphenyl groups). 3 and R 4 They may be different, but it is more preferable that they be the same group. A preferred example of a compound represented by the above general formula (5) is one in which R 5 ~R 7 Examples of triester phosphite compounds include those in which each is independently an alkyl group, aryl group (e.g., phenyl group, naphthyl group, etc.), or alkylaryl group (e.g., methylphenyl group, dimethylphenyl group, trimethylphenyl group (e.g., mesityl group, etc.), isopropylphenyl group, isopropylmethylphenyl group (e.g., thymyl group, etc.), and other alkylphenyl groups). 5 ~R 7 These may be different from each other, but it is more preferable that they be the same group. These compounds may be used individually or in combination of two or more.

[0059] The content of component (B) in the lubricating oil composition is preferably 0.010% by mass or more, or 0.025% by mass or more, or 0.030% by mass or more, as phosphorus, based on the total amount of the composition, from the viewpoint of further improving wear resistance, seizure resistance, and oxidation stability. Furthermore, the content of component (B) is preferably 0.100% by mass or less, or 0.085% by mass or less, or 0.075% by mass or less, as phosphorus, based on the total amount of the composition, from the viewpoint of further improving seizure resistance, fatigue resistance, and oxidation stability, as well as further improving the transmission torque capacity of the wet clutch. In one embodiment, the content of component (B) may be 0.010 to 0.100% by mass, or 0.025 to 0.085% by mass, or 0.030 to 0.75% by mass, as phosphorus, based on the total amount of the composition.

[0060] <(C) Calcium-based cleaning agent> The lubricating oil composition of the present invention contains one or more calcium-based detergents (hereinafter sometimes referred to as "component (C)"), including one or more calcium phenate detergents. By including a calcium phenate detergent in component (C), it is possible to increase the transmission torque capacity of the wet clutch. Component (C) may be one calcium-based detergent alone, or two or more calcium-based detergents may be used in combination. Furthermore, component (C) may consist of one or more calcium phenate detergents, or it may contain one or more calcium phenate detergents and one or more calcium detergents other than calcium phenate detergents. Examples of calcium detergents other than calcium phenate detergents include calcium sulfonate detergents and calcium salicylate detergents.

[0061] Examples of calcium phenate cleaning agents include the overbasic calcium salts of compounds having the structure shown in the following general formula (7).

[0062] [ka] In general formula (7), R 11R represents a linear or branched, saturated or unsaturated alkyl or alkenyl group with 6 to 21 carbon atoms, m represents an integer from 0 to 9, A represents a sulfide (-S-) group or a methylene (-CH2-) group, and x represents an integer from 1 to 3. 11 x may be a combination of two or more different groups, and x may be a combination of multiple different integers. When A is a methylene group, x is preferably 1. -A in each aromatic ring x - The substitution site of the group is typically the orthogonal or para-position relative to the hydroxyl group, usually the orthogonal position.

[0063] R in general formula (7) 11 The carbon number is preferably 9 or more from the viewpoint of increasing solubility in the base oil, and preferably 18 or less, more preferably 15 or less from the viewpoint of ease of manufacture, and in one embodiment it may be 9 to 18 or 9 to 15.

[0064] In general formula (2), m is preferably between 0 and 3.

[0065] Preferred examples of calcium sulfonate-based detergents include calcium salts of alkyl aromatic sulfonic acids obtained by sulfonating alkyl aromatic compounds, or their basic or overbasic salts. The weight-average molecular weight of the alkyl aromatic compound is preferably 400 to 1500, and more preferably 700 to 1300. Examples of alkyl aromatic sulfonic acids include so-called petroleum sulfonic acids and synthetic sulfonic acids. Examples of petroleum sulfonic acids include alkyl aromatic compounds obtained by sulfonating the lubricating oil fraction of mineral oil, and so-called mahogany acid, which is a by-product during the production of white oil. Examples of synthetic sulfonic acids include alkylbenzenes having linear or branched alkyl groups, obtained by recovering by-products in alkylbenzene production plants that are raw materials for detergents, or by alkylating benzene with polyolefins. Another example of synthetic sulfonic acids is obtained by sulfonating alkylnaphthalenes such as dinonylnaphthalene. Furthermore, there are no particular restrictions on the sulfonating agent used when sulfonating these alkyl aromatic compounds; for example, fuming sulfuric acid or anhydrous sulfuric acid can be used.

[0066] Examples of calcium salicylate cleaning agents include calcium salicylate or its basic or overbasic salts. A preferred example of calcium salicylate is the calcium salicylate represented by the following general formula (8).

[0067] [ka] In general formula (8), R 12 Each of these independently represents an alkyl or alkenyl group having 14 to 30 carbon atoms (preferably 14 to 24, or 14 to 20, or 14 to 18), and a represents 1 or 2, preferably 1. When a = 2, R 12 This can be a combination of different bases.

[0068] A preferred form of the calcium salicylate-based cleaning agent is a calcium salicylate or its basic or overbasic salt, where a=1 in the general formula (8) above.

[0069] The method for producing calcium salicylate is not particularly limited, and known methods for producing monoalkyl salicylate can be used. For example, calcium salicylate can be obtained by reacting a monoalkyl salicylic acid, obtained by alkylating with an olefin using phenol as a starting material and then carboxylating with carbon dioxide, or by reacting a monoalkyl salicylic acid, obtained by alkylating with an equivalent amount of the above olefin using salicylic acid as a starting material, with a metal base such as calcium oxide or hydroxide, or by first converting these monoalkyl salicylic acids into alkali metal salts such as sodium salts or potassium salts and then performing metal exchange with a calcium salt.

[0070] The method for obtaining overbasicated calcium phenate, sulfonate, or salicylate is not particularly limited, but for example, overbasicated calcium phenate, sulfonate, or salicylate can be obtained by reacting calcium phenate, sulfonate, or salicylate with a calcium base such as calcium hydroxide in the presence of carbon dioxide.

[0071] The base number of component (C) is not particularly limited, but is preferably 50 to 500 mg KOH / g, more preferably 100 to 400 mg KOH / g, and especially preferably 200 to 350 mg KOH / g. In this specification, the base number refers to the base number measured by the perchloric acid method in accordance with ASTM D 2896.

[0072] The content of component (C) in the lubricating oil composition is preferably 0.008% by mass or more, or 0.009% by mass or more, or 0.010% by mass or more, as calcium content, on a basis of the total composition, from the viewpoint of further improving wear resistance, seizure resistance, oxidation stability, and the transmission torque capacity and fastening performance of the wet clutch. Furthermore, the content of component (C) is preferably 0.040% by mass or less, or 0.038% by mass or less, or 0.036% by mass or less, as calcium content, on a basis of the total composition, from the viewpoint of facilitating the reduction of the ratio MB / MCa of boron content (MB) to calcium content (MCa) in the composition, as described later, to an upper limit or less. In one embodiment, the content of component (C) may be 0.008 to 0.040% by mass, or 0.009 to 0.040% by mass, or 0.010 to 0.040% by mass, or 0.009 to 0.038% by mass, or 0.010 to 0.036% by mass, based on the total amount of the composition, as calcium.

[0073] Component (C) may contain only one or more calcium phenate cleaning agents, or it may further contain one or more calcium-based cleaning agents other than calcium phenate cleaning agents (e.g., calcium sulfonate cleaning agent, calcium phenate cleaning agent, etc.). However, from the viewpoint of further increasing the transmission torque capacity of the wet clutch, the ratio of phenate to the total soap groups of component (C), that is, the ratio of the total soap groups of the phenate cleaning agent in terms of organic acids to the total soap groups of component (C) in terms of organic acids, is preferably 65 to 100% by mass, more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, and in one embodiment it may be 95 to 100% by mass. In this specification, the soap group of a metal-based detergent means the conjugate base of the organic acid constituting the soap component of the metal-based detergent (for example, an alkyl salicylate anion in the case of a salicylate detergent, an alkylbenzene sulfonate anion in the case of a sulfonate detergent, and an alkylphenate anion in the case of a phenate detergent). Generally, in the field of lubricants, metal-based detergents used are organic acid metal salts capable of forming micelles in the base oil (for example, alkali or alkaline earth metal alkyl salicylates, alkali or alkaline earth metal alkylbenzene sulfonates, and alkali or alkaline earth metal alkyl phenates, etc.), or mixtures of said organic acid metal salts and basic metal salts (for example, hydroxides, carbonates, borates, etc. of the alkali or alkaline earth metals constituting said organic acid metal salts). Such organic acids typically have in one molecule at least one polar group (e.g., a carboxyl group, a sulfo group, a phenolic hydroxyl group, etc.) that has Brønsted acidity and can form salts with a metal base, and at least one lipophilic group such as a linear or branched alkyl group (e.g., a linear or branched alkyl group having 6 or more carbon atoms, etc.).

[0074] <(D) Succinimide dispersant> The lubricating oil composition of the present invention contains one or more succinimide dispersants (hereinafter sometimes referred to as "component (D)"), which include one or more boron-containing succinimide dispersants. By including a boron-containing succinimide dispersant in component (D), wear resistance and seizure resistance are improved, and the transmission torque capacity of the wet clutch can be increased. Component (D) may be one succinimide dispersant used alone, or two or more succinimide dispersants may be used in combination. Furthermore, component (D) may consist of one or more boron-containing succinimide dispersants, or it may contain one or more boron-containing succinimide dispersants and one or more boron-free succinimide dispersants.

[0075] Preferred examples of succinimide ashless dispersants include succinimides and / or modified succinimides having at least one alkyl group or alkenyl group in the molecule.

[0076] Examples of succinimides having at least one alkyl or alkenyl group in the molecule include compounds represented by the following general formulas (9) or (10).

[0077] [ka]

[0078] In general formula (9), R 13 R represents an alkyl or alkenyl group having 40 to 400 carbon atoms, and d represents an integer from 1 to 5, preferably from 2 to 4. 13 The number of carbon atoms is preferably 40 or more, more preferably 60 or more, from the viewpoint of solubility in the lubricating oil base oil, and preferably 400 or less, more preferably 350 or less, from the viewpoint of improving the low-temperature fluidity of the lubricating oil composition, and in one embodiment it may be 40 to 400 or 60 to 350. 13 The most preferred group is a polybutenyl group.

[0079] In general formula (10), R 14 and R15 Each of these independently represents an alkyl or alkenyl group having 40 to 400 carbon atoms, and may be a combination of different groups. Also, e represents an integer from 0 to 4, preferably 1 to 4, and more preferably 1 to 3. 14 and R 15 The number of carbon atoms is preferably 40 or more, more preferably 60 or more, from the viewpoint of solubility in the lubricating oil base oil, and preferably 400 or less, more preferably 350 or less, from the viewpoint of improving the low-temperature fluidity of the lubricating oil composition, and in one embodiment it may be 40 to 400 or 60 to 350. 14 and R 15 The most preferred group is a polybutenyl group.

[0080] The alkyl or alkenyl group (R) in formulas (9) and (10) 13 ~R 15 The group may be linear or branched, and preferably, for example, branched alkyl groups or branched alkenyl groups derived from olefin oligomers such as propylene, 1-butene, and isobutene, or from co-oligomers of ethylene and propylene. Among these, branched alkyl groups or alkenyl groups derived from isobutene oligomers, commonly called polyisobutylene, or polybutenyl groups are most preferred. The alkyl or alkenyl group (R) in formulas (9) and (10) 13 ~R 15 The preferred number-average molecular weight of ) is 800 to 3500, more preferably 1000 to 3500.

[0081] Succinimides having at least one alkyl or alkenyl group in the molecule include so-called monotype succinimides represented by general formula (9), in which succinic anhydride is attached to only one end of the polyamine chain, and so-called bistype succinimides represented by general formula (10), in which succinic anhydride is attached to both ends of the polyamine chain. The lubricating oil composition may contain either monotype succinimides or bistype succinimides, or both may be included as a mixture. The content of bistype succinimides or their derivatives (modified products) in component (C) is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total amount of component (C) (100% by mass).

[0082] The method for producing succinimide having at least one alkyl or alkenyl group in the molecule is not particularly limited. For example, succinimide can be obtained as a condensation reaction product (condensation product) by reacting alkyl or alkenyl succinic acid or its anhydride having an alkyl or alkenyl group having 40 to 400 carbon atoms with a polyamine. Alkyl or alkenyl succinic acid or its anhydride can be obtained by reacting a compound having an alkyl or alkenyl group having 40 to 400 carbon atoms with maleic anhydride at 100 to 200°C. As component (C), the condensation product may be used as is, or it may be converted into a derivative (modified product) described later and used. The condensation product of alkyl or alkenyl succinic acid or its anhydride with a polyamine may be a bis-type succinimide (see general formula (10)) in which both ends of the polyamine chain are imidized, or a mono-type succinimide (see general formula (9)) in which only one end of the polyamine chain is imidized, or a mixture thereof. Examples of polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine, as well as mixtures thereof, and a polyamine raw material containing one or more selected from these can preferably be used. The polyamine raw material may or may not further contain ethylenediamine, but from the viewpoint of improving the performance of the condensation product or its derivative as a dispersant, the ethylenediamine content in the polyamine raw material is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, based on the total amount of the polyamine raw material. Succinimide obtained as a condensation reaction product of alkyl or alkenyl succinic acid having an alkyl or alkenyl group having 40 to 400 carbon atoms, or their anhydrides, and a mixture of two or more polyamines is a mixture of compounds having different d or e in general formula (9) or (10).

[0083] Component (D) contains one or more boron-containing succinimide dispersants. The boron-containing succinimide dispersant can be obtained as boric acid-modified succinimide (boron-modified succinimide, or borated succinimide) by reacting the above-mentioned unmodified succinimide with boric acid, thereby neutralizing or amidating some or all of the remaining amino groups and / or imino groups.

[0084] Examples of modified succinimides include: (i) Boron-modified succinimide (boronated succinimide), in which some or all of the remaining amino and / or imino groups are neutralized or amidated by reacting succinimide with boric acid; (ii) Oxygen-containing organic compound modified succinimide in which some or all of the remaining amino groups and / or imino groups are neutralized or amidated by reacting the above succinimide with a monocarboxylic acid having 1 to 30 carbon atoms such as fatty acids, a polycarboxylic acid having 2 to 30 carbon atoms (e.g., oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc.), anhydrides or ester compounds thereof, alkylene oxide having 2 to 6 carbon atoms, or a hydroxy(poly)oxyalkylene carbonate; (iii) Phosphate-modified succinimide in which some or all of the remaining amino groups and / or imino groups are neutralized or amidated by reacting the succinimide with phosphoric acid; (iv) Sulfur-modified succinimide obtained by reacting the above succinimide with a sulfur compound; and (v) Modified succinimide obtained by applying a combination of two or more modifications selected from modification with an oxygen-containing organic compound, boron modification, phosphate modification, and sulfur modification to the above succinimide, We can list some examples.

[0085] (D) The weight-average molecular weight of component (D) is preferably 1,000 to 20,000, more preferably 1,000 to 15,000, and particularly preferably 2,000 to 9,000. If component (C) contains two or more succinimide dispersants, it is preferable that the weight-average molecular weight of each succinimide dispersant is within the above range.

[0086] The boron content of component (D) in the lubricating oil composition is preferably 0.010% by mass or more on a basis of the total composition, from the viewpoint of further improving wear resistance, seizure resistance, and the transmission torque capacity of the wet clutch. Furthermore, the boron content of component (D) is less than 0.030% by mass, preferably 0.029% by mass or less, from the viewpoint of improving fatigue resistance. In one embodiment, the boron content of component (D) may be 0.010% by mass or more and less than 0.030% by mass, or 0.010 to 0.029% by mass, on a basis of the total composition.

[0087] The nitrogen content of component (D) in the lubricating oil composition is preferably 0.030% by mass or more, or 0.035% by mass or more, or 0.040% by mass or more, based on the total amount of the composition, from the viewpoint of further enhancing oxidation stability (base number maintenance). Furthermore, the nitrogen content of component (D) is preferably 0.055% by mass or less, or 0.050% by mass or less, or 0.045% by mass or less, based on the total amount of the composition, from the viewpoint of further enhancing gear lubrication performance (seizure resistance and fatigue resistance). In one embodiment, the nitrogen content of component (D) may be 0.030 to 0.055% by mass, or 0.035 to 0.050% by mass, or 0.040 to 0.045% by mass.

[0088] <(E) Oil-based friction modifiers> The lubricating oil composition of the present invention contains one or more oil-based friction modifiers (hereinafter sometimes referred to as "component (E)"). Component (E) may be one oil-based friction modifier used alone, or two or more oil-based friction modifiers may be used in combination.

[0089] Examples of oily friction modifiers include compounds with 6 to 50 carbon atoms that contain one or more heteroatoms selected from oxygen, nitrogen, and sulfur atoms in their molecules. Preferred examples of oily friction modifiers include aliphatic amines, fatty acid amides, fatty acid hydrazides, aliphatic imide compounds, aliphatic ureas, fatty acid esters, fatty acid metal salts, aliphatic alcohols, aliphatic ethers, etc., which have at least one linear or branched alkyl or alkenyl group with 6 to 30 carbon atoms in their molecules.

[0090] Examples of amide-based friction modifiers include condensation products (fatty acid amide friction modifiers) of fatty acids having 7 to 30 carbon atoms, preferably 8 to 30, 10 to 30, 12 to 24, 12 to 20, or 12 to 18 carbon atoms, with aliphatic primary or secondary amine compounds, aliphatic primary or secondary alkanolamine compounds, aliphatic polyamines, or ammonia. The above aliphatic primary or secondary amine compounds preferably have an alkyl or alkenyl group having 1 to 30 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 4 carbon atoms, and in one embodiment have a methyl group or an ethyl group. The above aliphatic primary or secondary alkanolamine compounds preferably have an alkylene or alkenylene group having 1 to 30 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 4 carbon atoms, and in one embodiment have a methylene or ethylene group. Preferred examples of the above-mentioned aliphatic polyamines include linear or branched aliphatic polyamines having 3 to 11 nitrogen atoms, such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine. Branched polyamines are structural isomers of linear polyamines and have one or more tertiary amino groups. Aliphatic polyamines may also be mixtures of two or more types. The number of nitrogen atoms in the aliphatic polyamine is preferably 3 to 6, and particularly preferably 4 to 6. The above fatty acids may be straight-chain fatty acids or branched-chain fatty acids. Preferred examples of straight-chain fatty acids include enanthic acid, caproic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, vaccenic acid, elaidic acid, linoleic acid, linolenic acid, eleostearic acid, stearidonic acid, arachidic acid, gadoleic acid, eicosenoic acid, eicosapentaenoic acid, behenic acid, erucic acid, sardine acid, docosahexaenoic acid, lignoceric acid, herringic acid, and mixtures thereof. As a mixture containing two or more of the above fatty acids, fatty acids derived from natural oils and fats may be used. Examples of fatty acids derived from natural oils and fats include coconut oil fatty acids, palm kernel oil fatty acids, palm oil fatty acids, tuni oil fatty acids, tall oil fatty acids, corn oil fatty acids, rapeseed oil fatty acids, olive oil fatty acids, sesame oil fatty acids, soybean oil fatty acids, rice bran oil fatty acids, sunflower oil fatty acids, castor oil fatty acids, linseed oil fatty acids, fish oil fatty acids, beef tallow fatty acids, hydrogenated versions thereof, and mixtures thereof. Preferred examples of branched-chain fatty acids include those having a tertiary or quaternary carbon atom (i.e., branched) at the α, β, or γ position of the carbonyl carbon. In one embodiment, the branched-chain fatty acid has a tertiary or quaternary carbon atom at the α or β position of the carbonyl carbon. In one embodiment, the branched-chain fatty acid has a tertiary or quaternary carbon atom at the α position of the carbonyl carbon. Preferred examples of such branched-chain fatty acids include those represented by the following general formula (11).

[0091] [ka] (In general formula (11), f is an integer between 0 and 2, preferably 0 or 1, more preferably 0; R 16 R is a linear or branched alkyl group having 3 to 19 carbon atoms, preferably 4 to 19 carbon atoms; 17 R is a linear or branched alkyl group having 1 to 10 carbon atoms, preferably 2 to 10 carbon atoms; 18is a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom; (R 16 has a carbon number of) ≥ (R 17 has a carbon number of) ≥ (R 18 has a carbon number of); (R 16 has a carbon number of) + (R 17 has a carbon number of) + (R 18 has a carbon number of) + k + 2 is equal to the total carbon number of the branched fatty acid.) In one preferred embodiment, in the general formula (11), f is 0, R 16 is a linear or branched alkyl group having 3 to 19 carbon atoms, R 17 is a linear or branched alkyl group having 1 to 10 carbon atoms, and R 18 can be a hydrogen atom. Preferred examples of the branched fatty acid represented by the general formula (11) include 2-ethylhexanoic acid, 2-butyloctanoic acid, 2-decyltetradecanoic acid, 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl) octanoic acid (alias isostearic acid), and the like. Specific examples of the fatty acid amide friction modifier include lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, coconut oil fatty acid amide, synthetic mixed fatty acid amide having 12 to 13 carbon atoms, and the like.

[0092] Other examples of amide-based friction modifiers include hydrazides and ureids of fatty acids having 7 to 30 carbon atoms; aliphatic semicarbazides, aliphatic ureas, and aliphatic allophanic acid amides having alkyl or alkenyl groups having 7 to 30 carbon atoms; and their derivatives (modified products). An example of a derivative (modified product) of an amide-based friction modifier is a boron-modified product obtained by reacting the above amide compounds with boric acid or a borate. In these compounds, preferred examples of fatty acids having 7 to 30 carbon atoms include the fatty acids described above in relation to fatty acid amide friction modifiers, and preferred examples of alkenyl or alkenyl groups having 7 to 30 carbon atoms include alkyl or alkenyl groups corresponding to the fatty acids described above in relation to fatty acid amide friction modifiers. In this specification, "alkyl or alkenyl group corresponding to a fatty acid" refers to fatty acids (R 19 Aliphatic alcohols (R) obtained by reducing the carboxyl group of -CO2H 19 The alkyl or alkenyl group (R) obtained by removing the hydroxyl group from -CH2-OH) is obtained. 19 This refers to a -CH2- group. In the above explanation, "reducing the carboxyl group" and "removing the hydroxyl group" refer to conceptual operations and do not necessarily mean that the alkyl or alkenyl group corresponding to the fatty acid must be obtained from the fatty acid in the manner described above.

[0093] Examples of fatty acid hydrazide friction modifiers include condensation products of fatty acids having 7 to 30 carbon atoms, preferably straight-chain fatty acids, and unsubstituted or aliphatic-substituted hydrazines; and acid-modified derivatives thereof (for example, boron-modified products obtained by the reaction of the condensation product with boric acid or a borate). Preferred examples of fatty acids include the fatty acids described above in relation to fatty acid amide friction modifiers. Specific examples of fatty acid hydrazide friction modifiers include lauric acid hydrazide, tridecanoic acid hydrazide, myristic acid hydrazide, pentadecanoic acid hydrazide, palmitic acid hydrazide, heptadecanoic acid hydrazide, stearate hydrazide, oleic acid hydrazide, and erucic acid hydrazide.

[0094] Examples of aliphatic urea friction modifiers include aliphatic urea compounds having linear or branched (preferably linear) alkyl or alkenyl groups with 7 to 30 carbon atoms, preferably 10 to 30, 12 to 24, 12 to 20, or 12 to 18 carbon atoms, and acid-modified derivatives thereof (for example, boron-modified products obtained by the reaction of the urea compound with boric acid or a borate). Preferred examples of alkenyl or alkenyl groups with 7 to 30 carbon atoms include alkyl or alkenyl groups corresponding to the fatty acids described above in relation to fatty acid amide friction modifiers. Specific examples of aliphatic urea friction modifiers include dodecylurea, tridecylurea, tetradecylurea, pentadecylurea, hexadecylurea, heptadecylurea, octadecylurea, and oleylurea.

[0095] Other examples of amide-based friction modifiers include amide compounds of aliphatic hydroxy acids having a hydroxysubstituted alkyl or alkenyl group having 1 to 30 carbon atoms. These amide compounds can be obtained, for example, as condensation products of the aliphatic hydroxy acid with an aliphatic primary or secondary amine compound, or an aliphatic primary or secondary alkanolamine compound. The number of carbon atoms in the hydroxysubstituted alkyl or alkenyl group of the aliphatic hydroxy acid is preferably 1 to 10, more preferably 1 to 4, and in one embodiment, 1 or 2. The aliphatic hydroxy acid is preferably a linear aliphatic α-hydroxy acid, and in one embodiment, glycolic acid. The amine compound and alkanolamine compound preferably have an aliphatic hydrocarbon group having 1 to 30 carbon atoms, more preferably 10 to 30, or 12 to 24, or 12 to 20, or 12 to 18 carbon atoms. The aliphatic hydrocarbon group is preferably a linear saturated aliphatic hydrocarbon group.

[0096] Other examples of amide-based friction modifiers include amide compounds of fatty acids having 7 to 30 carbon atoms and amino acids (N-acylated amino acid friction modifiers). Preferred examples of fatty acids include the fatty acids described above in relation to fatty acid amide friction modifiers. Preferred examples of amino acids include N-methyl amino acids such as N-methylglycine, N-methyl-β-alanine, N-methylvaline, N-methylleucine, and N-methylisoleucine, among which N-methylglycine or N-methyl-β-alanine are particularly preferred. Specific examples of N-acylated amino acid friction modifiers include N-acylated N-methylglycine (e.g., N-oleoyl-N-methylglycine, etc.) and N-acylated N-methyl-β-alanine (e.g., N-oleoyl-N-methyl-β-alanine, etc.).

[0097] Examples of aliphatic imide-based friction modifiers include succinimides having linear or branched alkyl or alkenyl groups with 6 to 30 carbon atoms, and modified versions thereof with carboxylic acids, boric acid, phosphoric acid, or sulfuric acid. Examples of succinimide-based friction modifiers include bis(succinimide) compounds and mono(succinimide) compounds having an alkyl or alkenyl group with 8 to 30 carbon atoms, and their derivatives (modified products). Such succinimide compounds are represented, for example, by the following general formula (12) or (13).

[0098]

Chemical formula

[0099] The method for producing a succinimide compound that can be used as a succinimide-based friction modifier is not particularly limited. For example, an alkyl or alkenyl succinic acid or its anhydride having an alkyl or alkenyl group with 8 to 30 carbon atoms, preferably 12 to 22 carbon atoms, and a polyamine, its N-mono C 1-30 alkylated product or N-mono C 1-30The succinimide compound can be obtained as a condensation product by reaction with an alkenylate or a mixture thereof. As a succinimide-based friction modifier, the condensation product may be used as is, or it may be converted into a derivative (modified product) as described later. The condensation product of alkyl or alkenyl succinic acid or its anhydride and a polyamine may be a bis-type succinimide (see general formula (12)) in which both ends of the polyamine chain are imidized, or a mono-type succinimide (see general formula (13)) in which only one end of the polyamine chain is imidized, or a mixture thereof. Here, examples of polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and mixtures thereof, and a polyamine raw material containing one or more selected from these can preferably be used. The polyamine raw material may or may not contain ethylenediamine, but from the viewpoint of improving the performance of the condensation product or its derivative as a friction modifier, the ethylenediamine content in the polyamine raw material is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, based on the total amount of the polyamine raw material. 1-30 As an alkylated compound, a carbon atom is placed on the nitrogen atom at the end of the chain of the above polyamine. 1-30 N-mono-C having an alkyl group 1-30 Alkylated polyamines can preferably be used. N-monoC polyamines 1-30 As an alkenylated compound, C is located on the nitrogen atom at the end of the chain of the above polyamine. 1-30 N-monocarbon with alkenyl group 1-30 Alkenylated polyamines can preferably be used. In this specification, "C i-j "(i and j are integers)" means that the number of carbon atoms is between i and j.

[0100] Examples of derivatives (modified products) of succinimide compounds that can be used as succinimide-based friction modifiers include modified compounds obtained by reacting the above-mentioned succinimide compound with one or more selected from boric acid, phosphoric acid, carboxylic acids having 1 to 20 carbon atoms, and sulfur-containing compounds. Among these, boron-modified products obtained by reaction with boric acid or borate salts are preferably used.

[0101] Component (E) preferably contains one or more N-acylated nitrogen-containing compounds (hereinafter referred to as "component (E1)") having one or more aliphatic hydrocarbyl groups having 8 to 30 carbon atoms and / or one or more aliphatic hydrocarbyl carbonyl groups having 8 to 30 carbon atoms, and one or more amide bonds and / or one or more imide bonds in one molecule, wherein the aliphatic hydrocarbyl carbonyl groups may constitute part of the amide bonds and / or imide bonds. Preferred examples of aliphatic hydrocarbyl groups include alkyl or alkenyl groups corresponding to the fatty acids described above in relation to the above fatty acid amide friction modifier. Preferred examples of aliphatic hydrocarbyl carbonyl groups include aliphatic acyl groups corresponding to the fatty acids described above in relation to the above fatty acid amide friction modifier. In this specification, "aliphatic acyl group corresponding to a fatty acid" means fatty acid (R 19 Aliphatic acyl group (R) obtained by removing the -OH group from -CO2H) 19 This means -CO- group. Component (E) may consist of component (E1), or it may contain component (E1) and one or more other oily friction modifiers.

[0102] In one embodiment, component (E) preferably contains an amine-based friction modifier. The amine-based friction modifier may be used in combination with component (E1), for example. Examples of amine-based friction modifiers include aliphatic monoamines having linear or branched alkyl or alkenyl groups having 7 to 30 carbon atoms, preferably 10 to 30, or 12 to 24, more preferably 12 to 20 carbon atoms, preferably linear alkyl or alkenyl groups; aliphatic polyamines having linear or branched alkyl or alkenyl groups having 10 to 30 carbon atoms, preferably 12 to 24, more preferably 12 to 20 carbon atoms, preferably linear alkyl or alkenyl groups; and alkylene oxide adducts of these aliphatic amines. Preferred examples of the alkyl or alkenyl groups include alkyl or alkenyl groups corresponding to the fatty acids described above in relation to fatty acid amide friction modifiers. A preferred form of the amine-based friction modifier is an alkyl or alkenyl dialkanolamine represented by the following general formula (14).

[0103] [ka] In general formula (14), R 25 represents an alkyl or alkenyl group corresponding to the fatty acid described above in relation to the fatty acid amide friction modifier. i and j each independently represent an integer from 1 to 4, preferably an integer from 2 to 4, or an integer from 2 to 3, and may be 2 in one embodiment.

[0104] Examples of fatty acid ester-based friction modifiers include esters of linear or branched (preferably linear) fatty acids having 7 to 30 carbon atoms, preferably 10 to 30, or 12 to 24, or 12 to 20, or 12 to 18 carbon atoms, with aliphatic monohydric alcohols (e.g., methanol, ethanol, etc.) or aliphatic polyhydric alcohols (e.g., glycerin, trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol, erythritol, diglycerin, sorbitan, adonitol, arabitol, xylitol, allose, talose, triglycerin, dipentaerythritol, sorbitol, mannitol, isitol, inositol, dalucitol, polyglycerin, etc.). Preferred examples of fatty acids include the fatty acids described above in relation to fatty acid amide friction modifiers.

[0105] Examples of fatty acid metal salt-based friction modifiers include alkaline earth metal salts (magnesium salts, calcium salts, etc.) and zinc salts of straight-chain or branched fatty acids having 7 to 30 carbon atoms, preferably 10 to 30, 12 to 24, 12 to 20, or 12 to 18 carbon atoms, preferably straight-chain fatty acids. Preferred examples of fatty acids include the fatty acids described above in relation to fatty acid amide friction modifiers.

[0106] Examples of aliphatic alcohol-based friction modifiers include linear or branched alkyl or alkenyl alcohols having 7 to 30 carbon atoms, preferably 10 to 30, 12 to 24, 12 to 20, or 12 to 18 carbon atoms, preferably linear. Preferred examples of alkyl or alkenyl groups include alkyl or alkenyl groups corresponding to the fatty acids described above in relation to fatty acid amide friction modifiers.

[0107] The preferred content of component (E) in the lubricating oil composition may vary depending on the type of compound, but may be, for example, 0.10 to 3.00% by mass.

[0108] For example, if component (E) contains component (E1), the content of component (E1) is preferably 0.10% by mass or more, or 0.40% by mass or more, or 0.80% by mass or more, based on the total amount of the lubricating oil composition, from the viewpoint of improving the stick-slip prevention (shutder prevention) of the wet clutch, and preferably 3.00% by mass or less, or 2.00% by mass or less, or 1.50% by mass or less, from the viewpoint of ensuring a higher level of transmission torque capacity of the wet clutch, and in one embodiment it may be 0.10 to 3.00% by mass, or 0.40 to 2.00% by mass, or 0.80 to 1.50% by mass.

[0109] Furthermore, for example, if component (E) contains component (E1) and an oily friction modifier other than component (E1), the content of the oily friction modifier other than component (E1) is preferably 0.001% by mass or more, or 0.005% by mass or more, or 0.010% by mass or more, based on the total amount of the lubricating oil composition, from the viewpoint of improving the judder prevention performance of the wet clutch, and also preferably 0.100% by mass or less, or 0.080% by mass or less, or 0.050% by mass or less, from the viewpoint of ensuring a higher level of transmission torque capacity of the wet clutch, and in one embodiment it may be 0.001 to 0.100% by mass, or 0.005 to 0.080% by mass, or 0.010 to 0.050% by mass.

[0110] <(F) Poly(meth)acrylate viscosity index improver> In one preferred embodiment, the lubricating oil composition of the present invention may further contain one or more poly(meth)acrylates (hereinafter sometimes referred to as "component (F)") having a weight-average molecular weight of 10,000 to 100,000. In this specification, "(meth)acrylate" means "acrylate and / or methacrylate". Component (F) may be a single poly(meth)acrylate or a mixture of two or more poly(meth)acrylates.

[0111] (F) Component may be either a dispersed polyalkyl (meth)acrylate or a non-dispersed polyalkyl (meth)acrylate. From the viewpoint of further improving the transmission torque capacity and fastening performance of the wet clutch, dispersed polyalkyl (meth)acrylate can be more preferably used.

[0112] The weight-average molecular weight of component (F) is preferably 10,000 or more, or 20,000 or more, or 30,000 or more, from the viewpoint of improving the low-temperature fluidity of the lubricating oil composition, and preferably 100,000 or less, or 70,000 or less, or 50,000 or less, from the viewpoint of improving shear stability, and in one embodiment it may be 10,000 to 100,000, or 20,000 to 70,000, or 30,000 to 50,000. If component (F) is a mixture of multiple poly(meth)acrylates, it is preferable that the weight-average molecular weight of each poly(meth)acrylate is within the above range.

[0113] Component (F) acts as a viscosity index improver and / or pour point depressant. The content (total content) of component (F) in the lubricating oil composition is preferably 0.5% by mass or more, or 1.0% by mass or more, or 2.0% by mass or more, as resin content on a basis of the total lubricating oil composition, from the viewpoint of improving the low-temperature fluidity of the lubricating oil composition, and preferably 6.0% by mass or less, or 5.0% by mass or less, or 4.0% by mass or less, from the viewpoint of improving shear stability, and in one embodiment it may be 0.5 to 6.0% by mass, or 1.0 to 5.0, or 2.0 to 4.0. In this specification, resin content means polymer components with a molecular weight of 1,000 or more.

[0114] <(G) Antioxidant> In one preferred embodiment, the lubricating oil composition may further contain one or more amine-based antioxidants and / or one or more phenol-based antioxidants (hereinafter sometimes referred to as "component (G)"). Component (G) may be a single compound or a combination of two or more compounds.

[0115] Examples of amine-based antioxidants include aromatic amine-based antioxidants and hindered amine-based antioxidants. Examples of aromatic amine-based antioxidants include primary aromatic amine compounds such as alkylated α-naphthylamine; and secondary aromatic amine compounds such as diphenylamine, alkylated diphenylamine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, phenyl-β-naphthylamine, and alkylated phenyl-β-naphthylamine. As aromatic amine-based antioxidants, alkylated diphenylamine, alkylated phenyl-α-naphthylamine, or combinations thereof can be preferably used.

[0116] Examples of phenolic antioxidants include: 4,4'-methylenebis(2,6-di-tert-butylphenol); 4,4'-bis(2,6-di-tert-butylphenol); 4,4'-bis(2-methyl-6-tert-butylphenol); 2,2'-methylenebis(4-ethyl-6-tert-butylphenol); 2,2'-methylenebis(4-methyl-6-tert-butylphenol); 4,4'-butylidenebis(3-methyl-6-tert-butylphenol); 4,4'-isopropylidenebis(2,6-di-tert-butylphenol); 2,2'-methylenebis(4-methyl-6-nonylphenol); 2,2'-isobutylidenebis(4,6-dimethylphenol); 2,2'-methylenebis(4-methyl-6-cyclohexylphenol); 2,6-di-tert-butyl-4- Examples include methylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,4-dimethyl-6-tert-butylphenol; 2,6-di-tert-butyl-4-(N,N'-dimethylaminomethyl)phenol; 4,4'-thiobis(2-methyl-6-tert-butylphenol); 4,4'-thiobis(3-methyl-6-tert-butylphenol); 2,2'-thiobis(4-methyl-6-tert-butylphenol); bis(3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide; bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide; 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid esters; 3-methyl-5-tert-butyl-4-hydroxyphenol fatty acid esters, etc.Examples of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionates include octyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; decyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; dodecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; tetradecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate Examples include: hexadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; 2,2'-thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], etc.

[0117] If the lubricating oil composition contains an amine-based antioxidant as component (G), its content is preferably 0.1 to 1.0% by mass, more preferably 0.2 to 1.0% by mass, and even more preferably 0.3 to 0.9% by mass, based on the total amount of the lubricating oil composition, from the viewpoint of thermal oxidation stability. If the lubricating oil composition contains a phenol-based antioxidant as component (G), its content is preferably 0.1 to 1.0% by mass, more preferably 0.2 to 0.9% by mass, and even more preferably 0.3 to 0.8% by mass, based on the total amount of the lubricating oil composition, from the viewpoint of thermal oxidation stability.

[0118] <Other additives> In one embodiment, the lubricating oil composition may further include one or more selected from components (A) and (B) other than anti-wear agents or extreme pressure agents, polymers other than component (F), oil-soluble organic molybdenum compounds, corrosion inhibitors other than component (A), rust inhibitors, metal deactivators other than component (A), seal swelling agents, defoaming agents, anti-emulsifiers, and colorants.

[0119] Examples of anti-wear agents or extreme pressure agents other than components (A) and (B) include sulfur-based additives that do not fall under component (A), such as disulfides, polysulfides, sulfurized olefins, and sulfurized oils (sulfur-based extreme pressure agents); and sulfur-containing phosphorus compounds (phosphorus-sulfur-based anti-wear agents), such as thiophosphites, dithiophosphites, trithiophosphites, thiophosphates, dithiophosphates, trithiophosphates, and tetrathiophosphates. The lubricating oil composition may or may not contain anti-wear agents or extreme pressure agents other than components (A) and (B). If the lubricating oil composition contains anti-wear agents or extreme pressure agents other than components (A) and (B), the total content thereof is preferably more than 0% by mass and less than 0.020% by mass, or more than 0% by mass and less than 0.015% by mass, or more than 0% by mass and less than 0.010% by mass, based on the total amount of the lubricating oil composition.

[0120] Other polymers besides component (F) can be polymers known as additives for lubricating oils, other than poly(meth)acrylate. Examples of polymers other than component (F) include ethylene-α-olefin copolymers and their hydrides, copolymers of α-olefins and ester monomers having polymerizable unsaturated bonds, polyisobutylene and its hydrides, styrene-diene copolymers, styrene-maleic anhydride copolymers, ethylene-vinyl acetate copolymers and their hydrides, and polyalkylstyrene. Among these, ethylene-α-olefin copolymers or their hydrides are preferably used. In one embodiment, ethylene propylene copolymer or its hydride is preferably used as the ethylene-α-olefin copolymer or its hydride. In one embodiment, the weight-average molecular weight of the polymer other than component (F) may be, for example, 2,000 to 30,000, preferably 5,000 to 15,000. The lubricating oil composition may or may not contain polymers other than component (F). If the lubricating oil composition contains polymers other than component (F), the amount thereof is preferably more than 0% by mass and less than 5.0% by mass, or more than 0% by mass and less than 4.0% by mass, or more than 0% by mass and less than 2.0% by mass, based on the total amount of the lubricating oil composition.

[0121] Examples of oil-soluble organic molybdenum compounds include organic molybdenum compounds containing sulfur and organic molybdenum compounds that do not contain sulfur as a constituent element. Examples of organic molybdenum compounds containing sulfur include molybdenum dithiocarbamate compounds; molybdenum dithiophosphate compounds; molybdenum compounds (for example, molybdenum oxides such as molybdenum dioxide and molybdenum trioxide, molybdic acids such as orthomolybdic acid, paramolybdic acid, and (poly)molybdic acid, molybdates such as metal salts and ammonium salts of these molybdic acids, molybdenum sulfide such as molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, and polymolybdenum sulfide, molybdic acid, and metal salts or amine salts of molybdic acid) Examples of organic molybdenum compounds include those containing sulfur (e.g., molybdenum halides such as molybdenum chloride) and sulfur-containing organic compounds (e.g., alkyl(thio)xanthetes, thiadiazoles, mercaptothiadiazoles, thiocarbonates, tetrahydrocarbyl thiuram disulfide, bis(di(thio)hydrocarbyl dithiophosphonate) disulfide, organic(poly)sulfides, sulfur esters, etc.) or other organic compounds; and complexes of sulfur-containing molybdenum compounds such as the above-mentioned molybdenum sulfide and molybdic acid sulfide with alkenyl succinimide. The organic molybdenum compound may be a mononuclear molybdenum compound, or a polynuclear molybdenum compound such as a dinuclear molybdenum compound or a trinuclear molybdenum compound. Examples of organic molybdenum compounds that do not contain sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, and molybdenum salts of alcohols. The lubricating oil composition may or may not contain an oil-soluble organic molybdenum compound. If the lubricating oil composition contains an oil-soluble organic molybdenum compound, its content is preferably more than 0% by mass and less than 0.05% by mass, or more than 0% by mass and less than 0.03% by mass, or more than 0% by mass and less than 0.02% by mass, based on the total amount of the composition as molybdenum.

[0122] Other corrosion inhibitors besides component (A) include, for example, known corrosion inhibitors such as benzotriazole, tolyltriazole, and imidazole compounds. If the lubricating oil composition contains corrosion inhibitors other than component (A), the content is usually 0.005 to 5% by mass on a basis of the total amount of the lubricating oil composition.

[0123] As rust inhibitors, known rust inhibitors such as petroleum sulfonates, alkylbenzene sulfonates, dinonylnaphthalene sulfonates, alkenyl succinate esters, and polyhydric alcohol esters can be used. When a lubricating oil composition contains a rust inhibitor, its content is usually 0.005 to 5% by mass based on the total amount of the lubricating oil composition.

[0124] Other metal deactivators besides component (A) include, for example, known metal deactivators such as imidazoline, pyrimidine derivatives, mercaptobenzothiazole, benzotriazole and its derivatives, 2-(alkyldithio)benzimidazole, and β-(o-carboxybenzylthio)propionnitrile. When the lubricating oil composition contains metal deactivators other than component (A), the content thereof is usually 0.005 to 1% by mass on a basis of the total amount of the lubricating oil composition.

[0125] As the seal swelling agent, any compound commonly used as a seal swelling agent for lubricating oils can be used without particular limitations, such as ester-based, sulfur-based, and aromatic seal swelling agents. For example, known seal swelling agents that cause swelling of elastomer materials, such as alcohols, alkylbenzenes, substituted sulfolanes, and mineral oils, can be used. Alcohol-based seal swelling agents are low-volatility linear alkyl alcohols, and preferred examples include decyl alcohol, tridecyl alcohol, and tetradecyl alcohol. In this specification, if an alcohol-based seal swelling agent also corresponds to component (E), the content of the alcohol-based seal swelling agent shall also be counted as contributing to the content of component (E). Examples of alkylbenzenes that can be used as sealing swelling agents include dodecylbenzene, tetradecylbenzene, dinonylbenzene, and di(2-ethylhexyl)benzene. Examples of substituted sulfolanes that can be used as sealing swelling agents include substituted sulfolane compounds represented by the following general formula (15).

[0126] [ka] In general formula (15), R 26 R is a hydrocarbon group having 4 or more carbon atoms, preferably an alkyl or alkenyl group having 4 to 25 carbon atoms, more preferably 4 to 10 carbon atoms. 27 and R 28 Each is a hydrogen atom or an alkyl group having 7 or fewer carbon atoms (preferably a linear chain), preferably R 27 and R 28 One side is a hydrogen atom, the other side (preferably R 28 ) is a hydrogen atom or a methyl group, more preferably R 27 and R 28 Both are hydrogen atoms. 1 is an oxygen atom or a sulfur atom, preferably an oxygen atom. Mineral oils that can be used as seal swelling agents are typically low-viscosity mineral oils with a high naphthenic or aromatic content. The lubricating oil composition may or may not contain a seal swelling agent. If the lubricating oil composition contains a seal swelling agent, the amount is usually 0.01 to 3.0% by mass based on the total amount of the composition.

[0127] As the defoaming agent, known defoaming agents such as silicones, fluorosilicones, and fluoroalkyl ethers can be used. When the lubricating oil composition contains a defoaming agent, its content is usually 0.0005 to 1% by mass based on the total amount of the lubricating oil composition.

[0128] As an anti-emulsifier, known anti-emulsifiers such as polyalkylene glycol-based nonionic surfactants can be used. When the lubricating oil composition contains an anti-emulsifier, its content is usually 0.005 to 5% by mass based on the total amount of the lubricating oil composition.

[0129] As a coloring agent, known coloring agents such as azo compounds can be used.

[0130] <Lubricating oil composition> The kinematic viscosity of the lubricating oil composition at 100°C is 6.2 mm² from the viewpoint of improving energy efficiency. 2 The value is less than or equal to / s, and is preferably 4.5 mm from the viewpoint of further improving wear resistance, seizure resistance, and fatigue life. 2 / s or more, or 5.0mm 2 / s or more, or 5.5mm 2 It is 1 / s or more, and in one embodiment it is 4.5~6.2 mm 2 / s, or 5.0-6.2mm 2 / s, or 5.5-6.2mm 2 It could be / s.

[0131] The kinematic viscosity of the lubricating oil composition at 40°C is preferably 35.0 mm² from the viewpoint of further enhancing energy efficiency. 2 / s or less, or 32.5mm 2 / s or less, or 30.0mm 2 It is less than or equal to / s.

[0132] The viscosity index of the lubricating oil composition is preferably 155 or higher, or 156 or higher, or 157 or higher, from the viewpoint of improving the temperature-viscosity characteristics of the composition and further enhancing energy saving, wear resistance, seizure resistance, and fatigue life.

[0133] The sulfur content in the lubricating oil composition is preferably 0.050% by mass or less, more preferably 0.048% by mass or less, or 0.045% by mass or less, based on the total amount of the composition, from the viewpoint of improving wear resistance and the transmission torque capacity and fastening performance of the wet clutch. Furthermore, from the viewpoint of further improving gear lubrication performance (seizure resistance and fatigue resistance), the sulfur content in the lubricating oil composition is preferably 0.005% by mass or more, more preferably 0.010% by mass or more, or more preferably 0.015% by mass or more, based on the total amount of the composition. In one embodiment, the sulfur content in the lubricating oil composition may be 0.005% by mass to 0.050% by mass, or 0.010% to 0.048% by mass, or 0.015% to 0.045% by mass.

[0134] The phosphorus content in the lubricating oil composition is preferably 0.010% by mass or more, or 0.025% by mass or more, or 0.030% by mass or more, based on the total amount of the composition, from the viewpoint of further improving wear resistance and seizure resistance. Furthermore, the phosphorus content in the lubricating oil composition is preferably 0.100% by mass or less, or 0.085% by mass or less, or 0.075% by mass or less, based on the total amount of the composition, from the viewpoint of further improving seizure resistance, fatigue resistance, and oxidation stability, as well as further improving the transmission torque capacity of the wet clutch. In one embodiment, the phosphorus content in the lubricating oil composition may be 0.010 to 0.100% by mass, or 0.025 to 0.085% by mass, or 0.030 to 0.75% by mass, based on the total amount of the composition.

[0135] The ratio MS / MP of sulfur content MS (unit: mass%) in the lubricating oil composition to phosphorus content MP (unit: mass%) in the lubricating oil composition is 1.00 or less, preferably 0.95 or less, or 0.90 or less, from the viewpoint of improving wear resistance and seizure resistance. Furthermore, the ratio MS / MP is preferably 0.30 or more, 0.35 or more, or 0.40 or more, from the viewpoint of further improving seizure resistance, fatigue resistance, oxidation stability, and the transmission torque capacity of the wet clutch. In one embodiment, the ratio MS / MP may be 0.30 to 0.100, or 0.35 to 0.95, or 0.40 to 0.90.

[0136] From the viewpoint of improving fatigue resistance, the boron content in the lubricating oil composition is less than 0.030% by mass, preferably 0.029% by mass or less, based on the total amount of the composition. Furthermore, from the viewpoint of further improving wear resistance, seizure resistance, and the transmission torque capacity of the wet clutch, the boron content in the lubricating oil composition is preferably 0.010% by mass or more, based on the total amount of the composition. In one embodiment, the boron content in the lubricating oil composition may be 0.010% by mass or more and less than 0.030% by mass, or 0.010 to 0.029% by mass, based on the total amount of the composition.

[0137] The calcium content in the lubricating oil composition is preferably 0.008% by mass or more, or 0.009% by mass or more, on a total basis of the composition, from the viewpoint of further improving wear resistance, seizure resistance, oxidation stability, and the transmission torque capacity and fastening performance of the wet clutch. Furthermore, the calcium content in the lubricating oil composition is preferably 0.050% by mass or less, or 0.045% by mass or less, or 0.040% by mass or less, on a total basis of the composition, from the viewpoint of facilitating the reduction of the ratio of boron content (MB) to calcium content (MCa) in the composition, MB / MCa, to an upper limit or less, as described later. In one embodiment, the content of component (C) may be 0.008 to 0.050% by mass, or 0.008 to 0.045% by mass, or 0.009 to 0.040% by mass, on a total basis of the composition, as calcium.

[0138] The ratio MB / MCa of boron content MB (unit: mass%) in the lubricating oil composition to calcium content MCa (unit: mass%) in the lubricating oil composition is 0.800 or higher, preferably 0.805 or higher, or 0.810 or higher, from the viewpoint of improving wear resistance, seizure resistance, and the transmission torque capacity of the wet clutch. Furthermore, the ratio MB / MCa is 1.200 or lower, preferably 1.170 or lower, or 1.160 or lower, from the viewpoint of improving wear resistance, seizure resistance, fatigue resistance, oxidation stability, and the transmission torque capacity and fastening performance of the wet clutch. In one embodiment, the ratio MB / MCa may be 0.800 to 1.200, or 0.805 to 1.170, or 0.810 to 1.160.

[0139] From the viewpoint of further improving wear resistance, seizure resistance, and fatigue life in the endurance stage, the kinematic viscosity of the lubricating oil composition at 100°C after irradiating it with ultrasonic waves at a frequency of 10 kHz and a transducer amplitude of 28 μm for 10 hours, as measured by a lubricating oil shear stability test in accordance with JPI-5S-29-88, is preferably 5.5 mm². 2 It is / s or greater.

[0140] (Application) The lubricating oil composition of the present invention can be preferably used for lubricating transmissions equipped with a wet clutch (e.g., automatic transmissions, continuously variable transmissions, etc.), and can be preferably used for lubricating such transmissions mounted in automobiles, for example. [Examples]

[0141] The present invention will be described in more detail below based on examples and comparative examples. However, the present invention is not limited to these examples.

[0142] <Examples 1-12 and Comparative Examples 1-8> As shown in Tables 1 to 4, lubricating oil compositions of the present invention (Examples 1 to 12) and comparative lubricating oil compositions (Comparative Examples 1 to 8) were prepared. In the tables, "mass%" in the "Base Oil Composition" column means mass% based on the total amount of base oil (100% by mass), and in other columns, "mass%" means mass% based on the total amount of the lubricating oil composition (100% by mass). Also, "mass ppm" means mass ppm based on the total amount of the lubricating oil composition, and for element X, the notation "mass ppm / X" means mass ppm of element X based on the total amount of the composition. Details of each component are as follows.

[0143] (Lubricant base oil) O-1: API Group III base oil, kinematic viscosity (100°C): 3.883 mm 2 / s, kinematic viscosity (40℃): 15.65mm 2 / s, viscosity index: 142, sulfur content: 4 mass ppm, %C P :92.5, %C N :7.5, %CA :0 O-2: API Group III base oil, kinematic viscosity (100°C): 6.208 mm 2 / s, kinematic viscosity (40℃): 33.97mm 2 / s, viscosity index: 133, sulfur content: less than 10 ppm by mass, %C P :80.6, %C N :19.4, %C A :0 O-3: API Group II base oil, kinematic viscosity (100°C): 3.12 mm 2 / s, kinematic viscosity (40℃): 12.43mm 2 / s, viscosity index: 112, sulfur content: less than 10 ppm by mass, %C P :75.1, %C N :24.9, %C A :0 O-4: API Group IV base oil (SpectraSyn® 6, manufactured by Exxon Mobil Chemical), kinematic viscosity (100°C): 5.8 mm 2 / s, kinematic viscosity (40℃): 31mm 2 / s, viscosity index: 138, pour point: -57℃, flash point: 246℃ O-5: API Group IV base oil (SpectraSyn® 4, manufactured by Exxon Mobil Chemical), kinematic viscosity (100°C): 4.1 mm 2 / s, kinematic viscosity (40℃): 19mm 2 / s, viscosity index: 126, pour point: -66℃, flash point 220℃

[0144] ((A) Sulfur compounds) A-1: Thiadiazole compound (in general formula (1), a=b=2, R 1 =R 2 = nonyl group), sulfur content 35.0% by mass A-2 * Sulfurized olefin / sulfurized oil mixture, sulfur content 30.5% by mass

[0145] ((B) Phosphorus compounds) B-1: Diphenylhydrogen phosphite (in general formula (4), R 3 =R 4= Phosphite diester containing a phenyl group (including tautomer), phosphorus content 13.2% by mass B-2 * Dithiophosphate ester, phosphorus content 9.0% by mass, sulfur content 19.4% by mass

[0146] ((C) Calcium-based cleaning agent) C-1: Calcium sulfide phenate cleaning agent, base number 255 mg KOH / g, Ca content 0.25% by mass, sulfur content 3.5% by mass

[0147] ((D) Succinimide dispersant) D-1: Boron-containing succinimide ashless dispersant, nitrogen content 1.48% by mass, boron content 1.30% by mass D-2: Non-boron modified succinimide ashless dispersant, nitrogen content 1.44% by mass

[0148] ((E) Oil-based friction modifiers) E-1: Fatty acid amide friction modifier, condensation reaction product of isostearic acid and tetraethylenepentamine, nitrogen content 6.20% by mass, total base number (perchloric acid method) 81.0 mg KOH / g E-2: Aliphatic amine friction modifier, oleyldiethanolamine (in general formula (14), R 25 (=oleyl group, i=j=2)

[0149] (F) Poly(meth)acrylate: Dispersed poly(meth)acrylate, weight-average molecular weight: 40,000

[0150] (G) Antioxidants: Amine-based antioxidants, diphenylamine

[0151] Other performance additives: sealant swelling agent, defoaming agent (dimethyl silicone, kinematic viscosity (25℃): 160,000 mm) 2 / s)

[0152] [Table 1]

[0153] [Table 2]

[0154] [Table 3]

[0155] [Table 4]

[0156] (High-speed walk test) For each lubricating oil composition, the Last Non-Seizure Load (LNSL) was measured at a rotational speed of 1800 rpm using a high-speed four-ball test in accordance with JPI-5S-40-93. The results are shown in Tables 1-4. A higher LNSL value measured in this test indicates better seizure resistance. The wear resistance of each lubricating oil composition was evaluated by a high-speed four-ball test in accordance with JPI-5S-40-93. The diameter of the wear marks was measured after 30 minutes of operation at a rotational speed of 1200 rpm, a load of 392 N, and an oil temperature of 80°C. The results are shown in Tables 1 to 4. A smaller wear mark diameter measured in this test indicates better wear resistance.

[0157] (FALEX seizure test) The seizure resistance of each lubricating oil composition was evaluated using the FALEX seizure test in accordance with ASTM D3233 A. Under conditions of an oil temperature of 110°C, a steel pin sandwiched between two stationary steel V-blocks was rotated at 290 rpm, and the load at which seizure occurred (seizure load) was measured. The results are shown in Tables 1 to 4. A higher seizure load value measured in this test indicates better seizure resistance.

[0158] (Unisteel Test) For each lubricating oil composition, the rolling fatigue life of thrust bearings was measured using the Unisteel rolling fatigue testing machine (triple-type high-temperature rolling fatigue testing machine (TRF-1000 / 3-01H), manufactured by Tokyo Testing Machine Co., Ltd.) according to the Unisteel test (British Petroleum Institute method: IP305 / 79). For test bearings in which one raceway of a thrust needle bearing (NSK FNTA-2542C) was replaced with a flat test piece (material: SUJ2), the time until fatigue failure occurred in either the roller or the test piece was measured under conditions of a load of 7000N, surface pressure of 2GPa, rotation speed of 1450rpm, and oil temperature of 120℃. The vibration acceleration of the test section measured by the vibration accelerometer installed in the Unisteel rolling fatigue testing machine was 1.5m / s². 2 Fatigue damage was determined to have occurred when the time to fatigue damage was reached. From the time to fatigue damage in 10 repeated tests, the fatigue life was calculated as the 50% life (L50: the time when the cumulative probability reaches 50%) using a Weibull plot. The results are shown in Tables 1-4. A longer 50% life measured in this test indicates better fatigue resistance.

[0159] (ISOT oxidation stability test) The oxidation stability of each lubricating oil composition was evaluated using the ISOT test in accordance with JIS K2514. The test was conducted at an oil temperature of 165°C for 144 hours, and the increase in acid value (mgKOH / g) after the test was measured. The results are shown in Tables 1 to 4. A smaller increase in acid value after the test indicates better oxidation stability.

[0160] (SAE No. 2 friction test: Evaluation of the shift shock index) For each lubricating oil composition, dynamic friction tests were conducted using an SAE No. 2 testing machine (manufactured by Shinko Seiki) in accordance with JASO M348:2002. The static friction coefficient μ between the friction plate (NW461E material) and the steel plate after 10,000 cycles was measured. t and the coefficient of dynamic friction μ d The coefficient of static friction μ was measured. The results are shown in Tables 1-4. t A higher value indicates a larger torque transmission capacity for the wet clutch. Also, the dynamic friction coefficient μd A higher value indicates better tightening performance of the wet clutch.

[0161] (Evaluation results) The lubricating oil compositions of Examples 1 to 12 showed good results in terms of shear stability, seizure resistance, wear resistance, fatigue resistance, oxidation stability, and the transmission torque capacity and fastening performance of wet clutches. Comparative Example 1, which had an excessive sulfur content and an excessive ratio of sulfur content MS to phosphorus content MP MS / MP, showed inferior results in terms of wear resistance and the transmission torque capacity and fastening performance of the wet clutch. The composition of Comparative Example 2, which contained a sulfur-based additive (sulfurized olefin / sulfurized oil mixture) instead of component (A) (thiadiazole compound), showed inferior results in terms of wear resistance, fatigue resistance, oxidation stability, and the transmission torque capacity and fastening performance of the wet clutch. Comparative Example 3, in which the ratio of sulfur content MS to phosphorus content MP MS / MP was excessively high, showed inferior results in terms of wear resistance and seizure resistance. Comparative Example 4, which contained a sulfur-containing phosphorus compound (dithiophosphate ester) instead of component (B) (sulfur-free phosphorus compound), had an excessive sulfur content in the composition, and an excessive ratio of sulfur content MS to phosphorus content MP MS / MP in the composition, showed inferior results in terms of wear resistance, fatigue resistance, oxidation stability, and the transmission torque capacity and fastening performance of the wet clutch. Comparative Example 5, in which component (D) did not contain a boron-containing succinimide dispersant and the ratio of boron MB to calcium MCa in the composition MB / MCa was too low, showed inferior results in terms of wear resistance, seizure resistance, and transmission torque capacity of the wet clutch. The composition of Comparative Example 6, in which the ratio of boron MB to calcium MCa (MB / MCa) in the composition was excessively high, showed inferior results in terms of wear resistance, seizure resistance, oxidation stability, and the transmission torque capacity and fastening performance of the wet clutch. Comparative Example 7, in which the ratio of boron MB to calcium MCa (MB / MCa) in the composition was excessively high, showed inferior fatigue resistance.

Claims

1. A lubricating oil base oil comprising one or more mineral oil-based base oils, one or more synthetic base oils, or a combination thereof, (A) One or more thiadiazole compounds, (B) One or more phosphorus compounds, (C) One or more calcium-based cleaning agents, (D) One or more succinimide dispersants containing one or more boron-containing succinimide dispersants, (E) One or more oil-based friction modifiers, It contains, The sulfur content in the composition is 0.050% by mass or less based on the total amount of the composition. The boron content in the composition is less than 0.030% by mass on a basis of the total composition. The kinematic viscosity of the composition at 100°C is 6.2 mm². ２ / s or less, The ratio MS / MP of the sulfur content MS (unit: mass%) in the composition to the phosphorus content MP (unit: mass%) in the composition is 1.00 or less. A lubricating oil composition characterized in that the ratio MB / MCa of the boron content in the composition to the calcium content in the composition (MCa, mass%) is 0.80 to 1.

20.

2. The lubricating oil composition according to claim 1, wherein the content of component (A) is 0.010 to 0.050% by mass as sulfur content on a basis of the total composition.

3. The lubricating oil composition according to claim 1 or 2, wherein the content of component (B) is 0.010 to 0.100% by mass as phosphorus on a basis of the total composition.

4. The lubricating oil composition according to claim 1 or 2, wherein the boron content MB in the composition is 0.010% by mass or more and less than 0.030% by mass on a basis of the total amount of the composition.

5. The lubricating oil composition according to claim 1 or 2, wherein the content of component (C) is 0.008 to 0.040% by mass as calcium content based on the total amount of the composition.

6. The lubricating oil composition according to claim 1 or 2, wherein the content of component (D) is 0.010% by mass or more and less than 0.030% by mass as boron content on a basis of the total composition.

7. The lubricating oil composition according to claim 1 or 2, wherein the component (E) contains 0.10 to 3.00% by mass of one or more N-acylated nitrogen-containing compounds, based on the total amount of the composition, each compound having (E1) one or more aliphatic hydrocarbyl groups having 8 to 30 carbon atoms and / or one or more aliphatic hydrocarbyl carbonyl groups having 8 to 30 carbon atoms and one or more amide bonds and / or one or more imide bonds in one molecule, and the aliphatic hydrocarbyl carbonyl groups may constitute part of the amide bonds and / or imide bonds.

8. (F) The lubricating oil composition according to claim 1 or 2, further comprising one or more poly(meth)acrylates having a weight-average molecular weight of 10,000 to 100,000.

9. (G) The lubricating oil composition according to claim 1 or 2, which contains 0.01 to 1.00% by mass of one or more amine-based antioxidants and / or one or more phenol-based antioxidants based on the total amount of the composition.

10. The kinematic viscosity of the aforementioned lubricating oil base oil at 100°C is 4.2 mm². ２ The lubricating oil composition according to claim 1 or 2, wherein the viscosity index is 120 or higher and the viscosity index is 120 or higher.

11. The lubricating oil composition according to claim 1 or 2, wherein the viscosity index of the lubricating oil composition is 155 or higher.

12. According to a lubricating oil shear stability test in accordance with JPI-5S-29-88, the kinematic viscosity of the lubricating oil composition at 100°C after irradiating it with ultrasonic waves at a frequency of 10 kHz and a transducer amplitude of 28 μm for 10 hours was 5.5 mm². ２ The lubricating oil composition according to claim 1 or 2, wherein the ratio is 1 / s or more.

13. A lubricating oil composition according to claim 1 or 2, used for lubricating a transmission equipped with a wet clutch.

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