Lubricating oil composition

Abstract

To provide a lubricant composition that has a low viscosity and can improve extreme pressure properties, wear resistance, and fatigue resistance tend to deteriorate as viscosity of lubricating oil decreases, and that can satisfy wet clutch performance required for transmissions while suppressing a decline in oxidation stability.SOLUTION: A lubricant composition comprises: a lubricant base oil comprising a mineral based base oil and / or a synthetic base oil; (A) a thiadiazole compound; (B) a sulfur-free phosphorus compound; (C) a calcium-based detergent including a calcium phenate detergent; (D) a succinimide dispersant containing a boron-containing succinimide dispersant; and (E) an oily agent based friction modifier, wherein a sulfur content is 0.050 mass% or less, a boron content is less than 0.030 mass%, kinematic viscosity at 100°C is 6.2 mm2 / s or less, a mass ratio MS / MP of the sulfur content MS to a phosphorus content MP is 1.00 or less, and a mass ratio MB / MCa of the boron content MB to a calcium content MCa is 0.80 to 1.20.SELECTED DRAWING: None

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, in particular an automatic transmission having a wet clutch or a continuously variable transmission having a wet clutch. [Background technology]

[0002] One of the means for saving energy in gear devices such as transmissions and final reduction gears is to reduce the viscosity of the lubricating oil. For example, transmissions and final reduction gears have gear bearing mechanisms, and by reducing the viscosity of the lubricating oil used in these devices, the stirring resistance and drag torque caused by the viscous resistance of the lubricating oil are reduced, improving the power transmission efficiency and, as a result, improving fuel economy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open 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] Patent Publication No. 2021-147521 [Patent Document 6] Patent Publication No. 2021-147517 [Patent Document 7] Japanese Patent Publication No. 2020-111736 [Patent Document 8] Japanese Patent Application Laid-Open No. 2011-132551 [Patent Document 9] Patent No. 4822684 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, reducing the viscosity of a lubricating oil improves fuel economy, but the resulting decrease in oil film thickness tends to reduce lubrication performance, such as extreme pressure, wear resistance, and fatigue resistance. One possible way to compensate for or improve these performance issues associated with lowering the viscosity of a lubricating oil is to add or increase the content of additives that function as extreme pressure agents and / or antiwear agents, such as sulfur-based additives, phosphorus-based additives, and phosphorus-sulfur-based additives. However, adding or increasing the amount of these additives can cause new problems, such as worsening the oxidation stability of the lubricating oil and worsening the friction characteristics of wet clutches. Therefore, there remains a need to solve the problems associated with lowering the viscosity of lubricating oils.

[0005] The present invention aims to provide a lubricating oil composition that has a low viscosity, yet improves the extreme pressure properties, wear resistance, and fatigue resistance that tend to deteriorate as the viscosity of lubricating oils decreases, and that is capable of suppressing a decrease in oxidation stability while also satisfying the wet clutch performance required for transmissions. [Means for solving the problem]

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

[11] . [1] A lubricating base oil comprising one or more mineral base oils, one or more synthetic base oils, or a combination thereof; (A) one or more thiadiazole compounds; (B) one or more non-sulfur containing phosphorus compounds; (C) one or more calcium-based detergents, including one or more calcium phenate detergents; and (D) one or more succinimide dispersants, including one or more boron-containing succinimide dispersants; and (E) one or more oily agent-based friction modifiers; 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 based on the total amount of the composition, The kinematic viscosity of the composition at 100°C is 6.2 mm 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 MB (unit: mass%) in the composition to the calcium content MCa (unit: mass%) in the composition is 0.80 to 1.20.

[0007] [2] The lubricating oil composition according to [1], wherein the content of the component (A) is 0.010 to 0.050 mass % in terms of sulfur content based on the total amount of the composition.

[0008] [3] The lubricating oil composition according to [1] or [2], wherein the content of the component (B) is 0.010 to 0.100 mass % in terms of phosphorus content based on the total amount of the 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 mass % or more and less than 0.030 mass % based on the total amount of the composition.

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

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

[0012] [7] The lubricating oil composition according to any one of [1] to [6], wherein the component (E) contains (E1) 0.10 to 3.00 mass% based on the total amount of the composition of one or more N-acylated nitrogen-containing compounds each 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 form part of the amide bonds and / or imide bonds.

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

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

[0015]

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

[0016]

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

[10] , wherein the lubricating oil composition has a viscosity index of 155 or more.

[0017]

[12] In a lubricating oil shear stability test in accordance with JPI-5S-29-88, the lubricating oil composition was irradiated with ultrasonic waves having a frequency of 10 kHz and an oscillator amplitude of 28 μm for 10 hours, and the kinematic viscosity of the composition at 100 ° C was 5.5 mm 2 The lubricating oil composition according to any one of [1] to

[11] , wherein the lubricating oil composition has a viscosity of 1000 saturates.

[0018]

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

[12] , which is used to lubricate a transmission equipped with a wet clutch. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a lubricating oil composition that has a low viscosity, improves extreme pressure properties, wear resistance, and fatigue resistance, which tend to deteriorate with the reduction in 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". When only the numerical value B is provided with a unit in such notation, the unit is also applied to the numerical value A. In this specification, the words "or" and "or" mean logical sum 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 (N is an integer of 3 or more.) for "E1,..., and / or E N " is equivalent to "E1,..., or E[[ID=1�]] i 、…、or E N 、or a combination thereof" (i is a variable that takes 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 contents of calcium, magnesium, zinc, phosphorus, sulfur, boron, barium, and molybdenum in oil are 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 is measured by chemiluminescence in accordance with JIS K2609. In addition, in this specification, "weight average molecular weight" means the weight average molecular weight measured by gel permeation chromatography (GPC) in terms of standard polystyrene. The GPC measurement conditions are as follows: [GPC measurement conditions] Equipment: Waters Corporation ACQUITY (registered trademark) APC UV RI system Columns: From the upstream side, two Waters Corporation ACQUITY® APC XT900A (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 (gel particle size 2.5 μm, column size (inner diameter x length) 4.6 mm x 150 mm) were connected in series. Column temperature: 40℃ Sample solution: tetrahydrofuran solution with a sample concentration of 1.0% by mass Eluent: tetrahydrofuran Solution injection volume: 20.0μL Detector: Differential refractive index detector Reference material: 8 standard polystyrenes (Agilent EasiCal (registered trademark) PS-1, manufactured by Agilent Technologies) (molecular weights: 2,698,000, 597,500, 290,300, 133,500, 70,500, 30,230, 9,590, 2,970) If the weight-average molecular weight measured under the above conditions is less than 10,000, change the column and standard substance to the following conditions and perform the measurement again. Columns: From the upstream side, 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) were connected in series. Reference material: 10 standard polystyrene samples (Agilent EasiCal (registered trademark) PS-1, manufactured by Agilent Technologies) (molecular weights: 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 major amount of a lubricating base oil and one or more additives other than the base oil. In the lubricating oil composition of the present invention, the lubricating base oil used comprises one or more mineral base oils, one or more synthetic base oils, or a combination thereof.

[0023] The lubricant base oil may be one or more mineral base oils, one or more synthetic base oils, or a mixture thereof. In one embodiment, the lubricant base oil may be API Group I base oil (hereinafter referred to as "API Group I base oil"), Group II base oil (hereinafter referred to as "API Group II base oil"), Group III base oil (hereinafter referred to as "API Group III base oil"), Group IV base oil (hereinafter referred to as "API Group IV base oil"), or Group V base oil (hereinafter referred to as "API Group V base oil"), or a mixture thereof. API Group I base oils are mineral base oils having a sulfur content of more than 0.03 mass% and / or less than 90 mass% saturates and a viscosity index of 80 or greater but less than 120. API Group II base oils are mineral base oils having a sulfur content of 0.03 mass% or less, a saturates content of 90 mass% or greater, and a viscosity index of 80 or greater but less than 120. API Group III base oils are mineral base oils with a sulfur content of 0.03% by mass or less, a saturates content of 90% by mass or more, and a viscosity index of 120 or more. 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 preferred examples thereof include ester-based base oils.

[0024] In one embodiment, component (A) can be preferably 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 base oils include paraffinic base oils, which are obtained by refining lubricating oil fractions obtained by atmospheric and / or vacuum distillation of crude oil through one or a combination of two or more refining processes selected from solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay treatment, etc., as well as 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 base oil P is preferably 60 or more, more preferably 65 or more, from the viewpoint of further improving 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 improving the solubility of the additives, and in one embodiment, may be 60 to 99, or 60 to 95, or 65 to 95, or 65 to 94.

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

[0028] %C of mineral base oil N is preferably 1 or more, more preferably 4 or more, from the viewpoint of enhancing the solubility of the additive, 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 in one embodiment, may be 1 to 40, or 4 to 35.

[0029] In this specification, %C P , %C N and %C A The percentages of paraffin carbon number to the total carbon number, naphthenic carbon number to the total carbon number, and aromatic carbon number to the total carbon number are determined by a method (ndM ring analysis) in accordance with ASTM D 3238-85. P, %C N and %C A The preferred range of %C is based on the value determined by the above method. For example, even in the case of a lubricating base oil that does not contain naphthenes, the %C determined by the above method is N can have a value greater than 0.

[0030] From the viewpoint of improving the viscosity-temperature characteristics of the composition, the content of saturated components in the mineral 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 the base oil. In this specification, saturated components refer to values ​​measured in accordance with ASTM D 2007-93.

[0031] The aromatic content of the mineral 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 the base oil. In one embodiment, it may be 0.1% by mass or more. By having the aromatic content be equal to or less than the above upper limit, it is possible to improve the low-temperature viscosity characteristics and viscosity-temperature characteristics in a fresh oil state, further improve fuel economy, and reduce evaporation loss of the lubricating oil, thereby reducing lubricating oil consumption. Furthermore, when additives are blended into the lubricating base oil, the effects of the additives can be effectively exerted. Furthermore, although the lubricating base oil may be free of aromatics, by having the aromatic content be equal to or greater than the above lower limit, the solubility of the additives can be improved.

[0032] In this specification, the aromatic content refers to a value measured in accordance with ASTM D 2007-93. The aromatic content typically includes alkylbenzenes, alkylnaphthalenes, anthracene, phenanthrene, and alkylated products thereof, as well as compounds having four or more fused benzene rings, pyridines, quinolines, phenols, naphthols, and other aromatic compounds having heteroatoms.

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

[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 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 base oil (all base oils) at 40°C is preferably 40mm from the viewpoint of improving energy saving and low temperature viscosity characteristics of the lubricating oil composition. 2 / s or less, or 30 mm 2 / s or less, or 22 mm 2 In this specification, the term "kinematic viscosity at 40°C" refers to the kinematic viscosity at 40°C measured in accordance with JIS K 2283-2000 using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument) as the measuring device.

[0036] The kinematic viscosity at 100°C of the lubricating base oil (all base oils) is preferably 6.0 mmHg from the viewpoint of further improving the energy saving and low temperature viscosity characteristics of the lubricating oil composition. 2 / s or less, or 5.5 mm 2 / s or less, or 5.0 mm 2 / s or less, and from the viewpoint of improving the wear resistance and seizure resistance, it is preferably 3.5 mm 2 / s or more, or 4.0 mm 2 / s or more, or 4.2 mm 2 / s or more, and in one embodiment, 3.5 to 6.0 mm 2 / s, or 4.0 to 5.5 mm 2 / s, or 4.0 to 5.0 mm 2 / s, or 4.2 to 5.0 mm 2 In this specification, the term "kinematic viscosity at 100°C" refers to the kinematic viscosity at 100°C measured in accordance with JIS K 2283-2000 using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument) as the measuring device.

[0037] From the viewpoint of improving the viscosity-temperature characteristics of the composition and further improving fuel economy and wear resistance, the viscosity index of the lubricating base oil (total base oil) is preferably 100 or more, more preferably 105 or more, even more preferably 110 or more, particularly preferably 115 or more, and most preferably 120 or more. In this specification, viscosity index means a viscosity index measured in accordance with JIS K 2283-2000 using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument) as the measuring device.

[0038] From the viewpoint of low-temperature fluidity of the entire lubricating oil composition, the pour point of the lubricating base oil (total 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. In this specification, pour point means the pour point measured in accordance with JIS K 2269-1987.

[0039] The sulfur content of a base oil depends on the sulfur content of the raw material. For example, when a raw material containing substantially no sulfur, such as a synthetic wax component obtained by the Fischer-Tropsch reaction, is used, a base oil containing substantially no sulfur can be obtained. Furthermore, when a raw material containing sulfur, such as slack wax obtained in the base oil refining process or microwax obtained in the refined wax process, is used, the sulfur content of the resulting base oil is usually 100 ppm by mass or more. The sulfur content of a lubricating 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 of a base oil refers to the amount of sulfur measured in accordance with JIS K 2541-2003.

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

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

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

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

[0044] [ka]

[0045] [ka]

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

[0047] The component (A) is represented by any one of the above general formulas (1) to (3), a and b are 2, and R 1 and R 2are each independently an alkyl group having 6 to 18 carbon atoms. 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 one of general formulas (1) to (3), and is preferably a bis(alkyldithio)thiadiazole compound having -S a -R 1 Group and -S b -R 2 A mono(alkyldithio)thiadiazole compound 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 is preferred. The preferred number of carbon atoms in the alkyl group is the same as in the bis(alkyldithio)thiadiazole compound.

[0048] The content of component (A) in the lubricating oil composition is 0.050 mass% or less, preferably 0.045 mass% or less, or 0.040 mass% or less, calculated as sulfur, based on the total amount of the composition, from the viewpoint of improving the transmission torque capacity and engagement performance of a wet clutch and the wear resistance of gears. Furthermore, the content of component (A) is preferably 0.010 mass% or more, calculated as sulfur, based on the total amount of the composition, from the viewpoint of further improving the wear resistance and fatigue resistance of gears and the oxidation stability of the lubricating oil, and from the viewpoint of further improving the transmission torque capacity and engagement performance of a wet clutch. In one embodiment, the content of component (A) may be 0.010 to 0.050 mass%, 0.010 to 0.045 mass%, or 0.010 to 0.040 mass%, calculated as sulfur, based on the total amount of the 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)"). As component (B), one type of phosphorus compound may be used alone, or two or more types of phosphorus compounds may be used in combination.

[0050] 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 represents a hydrocarbon group having 1 to 30 carbon atoms; R 4 represents a hydrocarbon group having 1 to 30 carbon atoms or a hydrogen atom; R 3 and R 4 may be the same or different from each other. The compound of general formula (4) is intended to include any tautomers thereof.)

[0052] [ka] (In general formula (5), R 5 represents a hydrocarbon group having 1 to 30 carbon atoms; R 6 and R 7 each independently represents a hydrocarbon group having 1 to 30 carbon atoms or a hydrogen atom; R 5 , R 6 , and R 7 may be the same or different from each other.)

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

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

[0055] Specific examples of metals that form metal salts with the 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. Of these, alkaline earth metals such as calcium and magnesium, zinc, or a combination thereof are preferred.

[0056] Examples of nitrogen-containing compounds that form ammonium salts with the 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 10 each independently represents a hydrogen atom, a hydrocarbyl group having 1 to 8 carbon atoms, or a hydrocarbyl group having 1 to 8 carbon atoms and a hydroxyl group; R8 ~R 10 At least one of the groups is a hydrocarbyl group having 1 to 8 carbon atoms or a hydrocarbyl group having 1 to 8 carbon atoms and a hydroxyl group.)

[0058] Preferable examples of the compound represented by the general formula (4) include compounds represented by the general formula (4) in which R 3 and R 4 are each independently an alkyl group having 3 to 18 carbon atoms (preferably 4 to 12), an aryl group (e.g., a phenyl group, a naphthyl group, etc.), or an alkylaryl group (e.g., an alkylphenyl group such as a methylphenyl group, a dimethylphenyl group, a trimethylphenyl group (e.g., a mesityl group, etc.), an isopropylphenyl group, an isopropylmethylphenyl group (e.g., a thymyl group, etc.)). 3 and R 4 may be different from each other, but it is more preferable that they are the same group. Preferable examples of the compound represented by the general formula (5) include compounds represented by the general formula (5) in which R 5 ~R 7 are each independently an alkyl group having 3 to 18 carbon atoms (preferably 4 to 12), an aryl group (e.g., a phenyl group, a naphthyl group, etc.), or an alkylaryl group (e.g., an alkylphenyl group such as a methylphenyl group, a dimethylphenyl group, a trimethylphenyl group (e.g., a mesityl group, etc.), an isopropylphenyl group, an isopropylmethylphenyl group (e.g., a thymyl group, etc.)). 5 ~R 7 may be different from each other, but are preferably the same group. These compounds may be used alone or in combination of two or more.

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

[0060] <(C) Calcium-based detergent> 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. The inclusion of a calcium phenate detergent in component (C) makes it possible to increase the transmission torque capacity of a wet clutch. As component (C), one calcium-based detergent may be used 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 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 detergents include overbased calcium salts of compounds having the structure shown in general formula (7) below.

[0062] [ka] In general formula (7), R 11represents a linear or branched, saturated or unsaturated alkyl or alkenyl group having 6 to 21 carbon atoms, m represents an integer of 0 to 9, A represents a sulfide (-S-) group or a methylene (-CH2-) group, and x represents an integer of 1 to 3. 11 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 position of the - group is typically the o- or p-position relative to the hydroxy group, typically the o-position.

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

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

[0065] A preferred example of the calcium sulfonate detergent is a calcium salt of an alkyl aromatic sulfonic acid, or a basic salt or overbased salt thereof, obtained by sulfonating an alkyl aromatic compound. The weight-average molecular weight of the alkyl aromatic compound is preferably 400 to 1500, 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 sulfonated alkyl aromatic compounds from the lubricating oil fraction of mineral oil, and so-called mahogany acid, which is a by-product produced during the production of white oil. An example of a synthetic sulfonic acid is a sulfonated alkylbenzene having a linear or branched alkyl group, which is obtained by recovering by-products from an alkylbenzene production plant used as a raw material for detergents, or by alkylating benzene with polyolefins. Another example of a synthetic sulfonic acid is a sulfonated alkylnaphthalene such as dinonylnaphthalene. The sulfonating agent used to sulfonate these alkyl aromatic compounds is not particularly limited, and for example, fuming sulfuric acid or sulfuric anhydride can be used.

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

[0067] [ka] In general formula (8), R 12 each 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 may be a combination of different groups.

[0068] A preferred embodiment of the calcium salicylate detergent is calcium salicylate, or a basic salt or overbased salt thereof, in which a=1 in the above general formula (8).

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

[0070] The method for obtaining an overbased calcium phenate, sulfonate, or salicylate is not particularly limited. For example, the overbased 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 gas.

[0071] The base number of component (C) is not particularly limited, but is preferably 50 to 500 mgKOH / g, more preferably 100 to 400 mgKOH / g, and particularly preferably 200 to 350 mgKOH / 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, in terms of calcium content based on the total amount of the composition, from the viewpoints of further improving wear resistance, seizure resistance, oxidation stability, and the transmission torque capacity and engagement performance of wet clutches. 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, in terms of calcium content based on the total amount of the composition, in terms of facilitating the ratio MB / MCa of the boron content (MB) to the calcium content (MCa) in the composition, as described below, to be equal to or less than the upper limit. In one embodiment, the content of component (C) may be 0.008 to 0.040 mass%, or 0.009 to 0.040 mass%, or 0.010 to 0.040 mass%, or 0.009 to 0.038 mass%, or 0.010 to 0.036 mass%, in terms of calcium content, based on the total mass of the composition.

[0073] Component (C) may contain only one or more calcium phenate detergents, or may further contain one or more calcium-based detergents other than calcium phenate detergents (e.g., calcium sulfonate detergents, calcium phenate detergents, etc.). However, from the viewpoint of further increasing the transmission torque capacity of a wet clutch, the proportion of phenate to all soap groups in component (C), i.e., the proportion of the mass of all soap groups of the phenate detergent, calculated as organic acids, to the mass of all soap groups in component (C), calculated as organic acids, is preferably 65 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, and in one embodiment, it may be 95 to 100 mass%. In this specification, the soap group of a metallic detergent refers to the conjugate base of the organic acid that constitutes the soap component of the metallic detergent (e.g., an alkyl salicylate anion in the case of a salicylate detergent, an alkyl benzene sulfonate anion in the case of a sulfonate detergent, or an alkyl phenate anion in the case of a phenate detergent). Generally, in the field of lubricating oils, the metallic detergents used are organic acid metal salts that can form micelles in the base oil (e.g., alkali or alkaline earth metal alkyl salicylates, alkali or alkaline earth metal alkyl benzene sulfonates, and alkali or alkaline earth metal alkyl phenates), or mixtures of such organic acid metal salts with basic metal salts (e.g., hydroxides, carbonates, borates, etc. of the alkali or alkaline earth metals that constitute the organic acid metal salts). Such organic acids usually have, in one molecule, at least one polar group (e.g., a carboxy group, a sulfo group, a phenolic hydroxy group, etc.) having Bronsted acidity capable of forming a salt 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)"), including one or more boron-containing succinimide dispersants. The inclusion of a boron-containing succinimide dispersant in Component (D) improves wear resistance and seizure resistance, and also increases the torque transmission capacity of wet clutches. Component (D) may be a single succinimide dispersant, or two or more succinimide dispersants may be used in combination. Component (D) may also consist of one or more boron-containing succinimide dispersants, or it may contain one or more boron-containing succinimide dispersants and one or more non-boron-containing 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 formula (9) or (10).

[0077] [ka]

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

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

[0080] The alkyl group or alkenyl group (R 13 ~R 15 ) may be linear or branched, and preferably includes, for example, a branched alkyl group or alkenyl group derived from an olefin oligomer such as propylene, 1-butene, or isobutene, or a cooligomer of ethylene and propylene. Among these, a branched alkyl group or alkenyl group derived from an oligomer of isobutene commonly called polyisobutylene, or a polybutenyl group, is most preferred. The alkyl group or alkenyl group (R 13 ~R 15 The number average molecular weight of the hydroxybenzoate is preferably 800 to 3,500, more preferably 1,000 to 3,500.

[0081] Succinimides having at least one alkyl or alkenyl group per molecule include so-called mono-type succinimides, represented by general formula (9), in which succinic anhydride is attached to only one end of the polyamine chain, and so-called bis-type 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 mono-type succinimides or bis-type succinimides, or a mixture of both. The content of bis-type 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 a succinimide having at least one alkyl or alkenyl group in the molecule is not particularly limited. For example, the succinimide can be obtained as a condensation reaction product (condensation product) by reacting an alkyl or alkenyl succinic acid or anhydride thereof having an alkyl or alkenyl group having 40 to 400 carbon atoms with a polyamine. The alkyl or alkenyl succinic acid or anhydride thereof 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 the condensation product may be converted into a derivative (modified product) as described below. The condensation product of an alkyl or alkenyl succinic acid or anhydride thereof 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, pentaethylenehexamine, and mixtures thereof. A polyamine raw material containing one or more selected from these is preferably used. The polyamine raw material may or may not further contain ethylenediamine. However, from the viewpoint of improving the performance of the condensation product or its derivative as a dispersant, the content of ethylenediamine in the polyamine raw material is preferably 0 to 10 mass %, more preferably 0 to 5 mass %, based on the total amount of the polyamine raw material. Succinimide obtained as a condensation reaction product between an alkyl or alkenyl succinic acid or anhydride thereof having an alkyl or alkenyl group having 40 to 400 carbon atoms 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 dispersants can be obtained as boric acid-modified succinimides (boron-modified succinimides or boronated succinimides) by reacting the unmodified succinimides with boric acid to neutralize or amidate some or all of the remaining amino and / or imino groups.

[0084] Examples of modified succinimides include: (i) the boron-containing succinimide, i.e., a boron-modified succinimide (boronated succinimide) in which the remaining amino groups and / or imino groups are partially or entirely neutralized or amidated by reacting boric acid with succinimide; (ii) Oxygen-containing organic compound-modified succinimide, in which the remaining amino groups and / or imino groups are partially or entirely neutralized or amidated by reacting the succinimide with a monocarboxylic acid having 1 to 30 carbon atoms such as a fatty acid, a polycarboxylic acid having 2 to 30 carbon atoms (for example, oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc.), an anhydride or ester compound thereof, an alkylene oxide having 2 to 6 carbon atoms, or a hydroxy(poly)oxyalkylene carbonate; (iii) a phosphoric acid-modified succinimide in which the remaining amino and / or imino groups are partially or entirely neutralized or amidated by reacting the succinimide with phosphoric acid; (iv) a sulfur-modified succinimide obtained by reacting the succinimide with a sulfur compound; and (v) A modified succinimide obtained by subjecting the above succinimide to a combination of two or more modifications selected from modification with an oxygen-containing organic compound, boron modification, phosphoric acid modification, and sulfur modification. Examples include:

[0085] The weight average molecular weight of component (D) is preferably 1000 to 20000, more preferably 1000 to 15000, and particularly preferably 2000 to 9000. When 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 based on the total amount of the composition, from the viewpoint of further improving wear resistance, seizure resistance, and the transmission torque capacity of wet clutches. 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 but less than 0.030% by mass, or 0.010 to 0.029% by mass, based on the total amount of the 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 improving oxidation stability (base number retention). 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 improving 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 modifier> The lubricating oil composition of the present invention contains one or more oiliness-based friction modifiers (hereinafter sometimes referred to as "component (E)"). As component (E), one oiliness-based friction modifier may be used alone, or two or more oiliness-based friction modifiers may be used in combination.

[0089] Examples of oil-based friction modifiers include compounds having 6 to 50 carbon atoms and containing one or more heteroatoms selected from oxygen, nitrogen, and sulfur atoms in the molecule. Preferred examples of oil-based 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, and aliphatic ethers, all of which have at least one linear or branched alkyl or alkenyl group having 6 to 30 carbon atoms in the molecule.

[0090] An example of an amide-based friction modifier is a condensation product (fatty acid amide friction modifier) ​​of a fatty acid having 7 to 30 carbon atoms, preferably 8 to 30, or 10 to 30, or 12 to 24, or 12 to 20, or 12 to 18 carbon atoms, with an aliphatic primary or secondary amine compound, an aliphatic primary or secondary alkanolamine compound, an aliphatic polyamine, or ammonia. The aliphatic primary or secondary amine compound preferably has 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 has a methyl group or an ethyl group. The aliphatic primary or secondary alkanolamine compound preferably has 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 has a methylene or ethylene group. Preferred examples of the aliphatic polyamine 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. The aliphatic polyamines may be a mixture 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 fatty acids may be straight-chain 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, herring acid, and mixtures thereof. Fatty acids derived from natural fats and oils may also be used as mixtures containing two or more of the above fatty acids. Examples of fatty acids derived from natural fats and oils include coconut oil fatty acids, palm kernel oil fatty acids, palm oil fatty acids, tung 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 products thereof, and mixtures thereof. Preferred examples of branched-chain fatty acids include branched-chain fatty acids having a tertiary or quaternary carbon atom (i.e., branched) at the α-, β-, or γ-position relative to the carbonyl carbon. In one embodiment, the branched-chain fatty acid has a tertiary or quaternary carbon atom at the α- or β-position relative to the carbonyl carbon. In one embodiment, the branched-chain fatty acid has a tertiary or quaternary carbon atom at the α-position relative to the carbonyl carbon. Preferred examples of such branched-chain fatty acids include branched-chain fatty acids represented by the following general formula (11):

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

[0092] Other examples of amide-based friction modifiers include hydrazides and ureidos 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 derivatives (modified products) thereof. Examples of derivatives (modified products) of amide-based friction modifiers include boron-modified products obtained by reacting the above-mentioned amide compounds with boric acid or borate salts. Among these compounds, preferred examples of the fatty acids having 7 to 30 carbon atoms include the fatty acids described above in connection with the fatty acid amide friction modifiers, and preferred examples of the alkenyl or alkenyl group having 7 to 30 carbon atoms include the alkyl or alkenyl group corresponding to the fatty acid described above in connection with the fatty acid amide friction modifiers. In this specification, the term "alkyl or alkenyl group corresponding to a fatty acid" refers to a fatty acid (R 19 Aliphatic alcohols (R 19 an alkyl or alkenyl group (R) obtained by removing the hydroxy group from 19 In the above explanation, "reducing a carboxy group" and "removing a hydroxy group" refer to conceptual operations, and do not necessarily mean that "an alkyl or alkenyl group corresponding to a fatty acid" must be obtained from a fatty acid in the manner explained 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, with unsubstituted or aliphatic-substituted hydrazine; and acid-modified derivatives thereof (for example, boron-modified products obtained by reacting the condensation products with boric acid or borate). Preferred examples of fatty acids include the fatty acids described above in relation to the fatty acid amide friction modifier. 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, stearic acid hydrazide, oleic acid hydrazide, and erucic acid hydrazide.

[0094] Examples of aliphatic urea friction modifiers include aliphatic urea compounds having a linear or branched (preferably linear) alkyl or alkenyl group having 7 to 30 carbon atoms, preferably 10 to 30, or 12 to 24, or 12 to 20, or 12 to 18 carbon atoms, and acid-modified derivatives thereof (for example, boron-modified products obtained by reacting the urea compound with boric acid or a borate salt). Preferred examples of the alkenyl or alkenyl group having 7 to 30 carbon atoms include alkyl or alkenyl groups corresponding to the fatty acids described above in connection with the fatty acid amide friction modifier. Specific examples of the aliphatic urea friction modifier include dodecyl urea, tridecyl urea, tetradecyl urea, pentadecyl urea, hexadecyl urea, heptadecyl urea, octadecyl urea, and oleyl urea.

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

[0096] Other examples of amide friction modifiers include amide compounds (N-acylated amino acid friction modifiers) of a fatty acid having 7 to 30 carbon atoms with an amino acid. Preferred examples of fatty acids include the fatty acids described above in relation to the fatty acid amide friction modifier. Preferred examples of amino acids include N-methylamino acids such as N-methylglycine, N-methyl-β-alanine, N-methylalanine, N-methylvaline, N-methylleucine, and N-methylisoleucine, with N-methylglycine or N-methyl-β-alanine being particularly preferred. Specific examples of N-acylated amino acid friction modifiers include N-acylated N-methylglycine (e.g., N-oleoyl-N-methylglycine), N-acylated-N-methyl-β-alanine (e.g., N-oleoyl-N-methyl-β-alanine), and the like.

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

[0098] [ka] In general formulas (12) and (13), R 20 and R 21 R each independently represents an alkyl or alkenyl group having 8 to 30 carbon atoms, preferably 12 to 22 or 12 to 18 carbon atoms. 22 and R 23 R each independently represents an alkylene group having 1 to 4 carbon atoms, preferably an alkylene group having 2 to 3 carbon atoms, or an ethylene group. 24 represents a hydrogen atom or an alkyl or alkenyl group having 1 to 30 carbon atoms, preferably a hydrogen atom. g represents an integer of 1 to 7, preferably 1 to 4 or 1 to 3. h represents an integer of 1 to 7, preferably 1 to 5, or 2 to 5, or 2 to 4.

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

[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 compounds with one or more compounds 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] The component (E) preferably contains (E1) one or more N-acylated nitrogen-containing compounds 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 imido bonds in one molecule, wherein the aliphatic hydrocarbyl carbonyl groups may constitute part of the amide bonds and / or imido bonds (hereinafter sometimes referred to as "component (E1)"). Preferred examples of the aliphatic hydrocarbyl groups include alkyl or alkenyl groups corresponding to the fatty acids described above in connection with the fatty acid amide friction modifier. Preferred examples of the aliphatic hydrocarbyl carbonyl groups include aliphatic acyl groups corresponding to the fatty acids described above in connection with the fatty acid amide friction modifier. In this specification, the term "aliphatic acyl group corresponding to a fatty acid" refers to a group of a fatty acid (R 19 aliphatic acyl groups (R 19 The component (E) may consist of the component (E1), or may contain the component (E1) and one or more other oily agent-based 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 a linear or branched alkyl or alkenyl group, preferably a linear alkyl or alkenyl group, having 7 to 30 carbon atoms, preferably 10 to 30 or 12 to 24, more preferably 12 to 20 carbon atoms; aliphatic polyamines having a linear or branched alkyl or alkenyl group, preferably a linear alkyl or alkenyl group, having 10 to 30 carbon atoms, preferably 12 to 24, more preferably 12 to 20 carbon atoms; and alkylene oxide adducts of these aliphatic amines. Preferred examples of the alkyl or alkenyl group include alkyl or alkenyl groups corresponding to the fatty acids described above in connection with the fatty acid amide friction modifier. A preferred embodiment 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 connection with the fatty acid amide friction modifier. i and j each independently represent an integer of 1 to 4, preferably an integer of 2 to 4, or an integer of 2 to 3, and in one embodiment may be 2.

[0104] Examples of fatty acid ester 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, iditol, inositol, dulcitol, polyglycerin, etc.). Preferred examples of fatty acids include the fatty acids described above in connection with the fatty acid amide friction modifier.

[0105] Examples of fatty acid metal salt friction modifiers include alkaline earth metal salts (magnesium salts, calcium salts, etc.) and zinc salts of straight-chain or branched-chain, preferably straight-chain, 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. Preferred examples of fatty acids include the fatty acids described above in relation to the fatty acid amide friction modifier.

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

[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 mass %.

[0108] For example, when component (E) includes 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 (shudder prevention) properties of the wet clutch, and is 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 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, when component (E) contains component (E1) and an oily agent-based friction modifier other than component (E1), the content of the oily agent-based friction modifier other than component (E1) is, from the viewpoint of improving the anti-shudder properties of the wet clutch, 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; and from the viewpoint of ensuring a higher level of transmission torque capacity of the wet clutch, preferably 0.100% by mass or less, or 0.080% by mass or less, or 0.050% by mass or less, and in one embodiment 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." As component (F), one type of poly(meth)acrylate may be used alone, or a mixture of two or more types of poly(meth)acrylates may be used.

[0111] The component (F) may be either a dispersion-type polyalkyl(meth)acrylate or a non-dispersion-type polyalkyl(meth)acrylate. From the viewpoint of further improving the transmission torque capacity and engagement performance of the wet clutch, the dispersion-type polyalkyl(meth)acrylate is 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 is 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 may be 10,000 to 100,000, or 20,000 to 70,000, or 30,000 to 50,000. When 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, expressed as resin content based on the total amount of the lubricating oil composition, from the viewpoint of improving the low-temperature fluidity of the lubricating oil composition; from the viewpoint of improving shear stability, it is preferably 6.0% by mass or less, or 5.0% by mass or less, or 4.0% by mass or less, and in one embodiment, it may be 0.5 to 6.0% by mass, or 1.0 to 5.0% by mass, or 2.0 to 4.0% by mass. In this specification, resin content refers to a polymer component having a molecular weight of 1,000 or more.

[0114] <(G) Antioxidants> 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)"). As Component (G), one type of compound may be used alone, or two or more types of compounds may be used in combination.

[0115] Examples of amine antioxidants include aromatic amine antioxidants and hindered amine antioxidants. Examples of aromatic amine 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 the aromatic amine antioxidant, alkylated diphenylamine, alkylated phenyl-α-naphthylamine, or a combination 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, and the like.Examples of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid esters 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. 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], and the like.

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

[0118] <Other additives> In one embodiment, the lubricating oil composition may further contain one or more selected from an antiwear or extreme pressure agent other than Component (A) and Component (B), a polymer other than Component (F), an oil-soluble organomolybdenum compound, a corrosion inhibitor other than Component (A), a rust inhibitor, a metal deactivator other than Component (A), a seal swelling agent, an antifoaming agent, a demulsifier, and a colorant.

[0119] Examples of antiwear or extreme pressure agents other than component (A) and component (B) include sulfur-based additives (sulfur-based extreme pressure agents) that do not fall under component (A), such as disulfides, polysulfides, sulfurized olefins, and sulfurized oils and fats; and sulfur-containing phosphorus compounds (phosphorus-sulfur-based antiwear agents), such as thiophosphites, dithiophosphites, trithiophosphites, thiophosphates, dithiophosphates, trithiophosphates, and tetrathiophosphates. The lubricating oil composition may or may not contain antiwear or extreme pressure agents other than component (A) and component (B). When the lubricating oil composition contains antiwear or extreme pressure agents other than component (A) and component (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] As the polymer other than component (F), polymers known as lubricating oil additives other than poly(meth)acrylates can be used. Examples of polymers other than component (F) include ethylene-α-olefin copolymers and hydrogenated products thereof, copolymers of α-olefins and ester monomers having polymerizable unsaturated bonds, polyisobutylene and hydrogenated products thereof, hydrogenated styrene-diene copolymers, styrene-maleic anhydride ester copolymers, ethylene-vinyl acetate copolymers and hydrogenated products thereof, and polyalkylstyrenes. Among these, ethylene-α-olefin copolymers or hydrogenated products thereof are preferably used. In one embodiment, ethylene-propylene copolymers or hydrogenated products thereof are preferably used as the ethylene-α-olefin copolymers or hydrogenated products thereof. 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 a polymer other than component (F). When the lubricating oil composition contains a polymer other than component (F), the content thereof is preferably more than 0 mass% and less than 5.0 mass%, or more than 0 mass% and less than 4.0 mass%, or more than 0 mass% and less than 2.0 mass%, based on the total amount of the lubricating oil composition.

[0121] Examples of oil-soluble organomolybdenum compounds include sulfur-containing organomolybdenum compounds and organomolybdenum compounds that do not contain sulfur as a constituent element. Examples of sulfur-containing organomolybdenum compounds include molybdenum dithiocarbamate compounds; molybdenum dithiophosphate compounds; molybdenum compounds (e.g., molybdenum oxides such as molybdenum dioxide and molybdenum trioxide; molybdic acids such as orthomolybdic acid, paramolybdic acid, and (poly)molybdic sulfide; metal salts of these molybdic acids; molybdates such as ammonium salts; molybdenum sulfides such as molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, and polymolybdenum sulfide; molybdic acid; and metal or amine salts of molybdic sulfide. and molybdenum halides such as molybdenum chloride.) with sulfur-containing organic compounds (e.g., alkyl(thio)xanthates, thiadiazoles, mercaptothiadiazoles, thiocarbonates, tetrahydrocarbylthiuram disulfides, bis(di(thio)hydrocarbyldithiophosphonate)disulfides, organic (poly)sulfides, sulfurized esters, etc.) or other organic compounds; and complexes of sulfur-containing molybdenum compounds such as the above molybdenum sulfide and molybdic acid with alkenyl succinimides. 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 organo-molybdenum compound. When the lubricating oil composition contains an oil-soluble organo-molybdenum compound, the content thereof is preferably more than 0 mass% and less than 0.05 mass%, more than 0 mass% and less than 0.03 mass%, or more than 0 mass% and less than 0.02 mass%, in terms of molybdenum amount, based on the total amount of the composition.

[0122] As the corrosion inhibitor other than component (A), for example, known corrosion inhibitors such as benzotriazole-based, tolyltriazole-based, and imidazole-based compounds can be used. When the lubricating oil composition contains a corrosion inhibitor other than component (A), the content thereof is usually 0.005 to 5 mass% based on the total amount of the lubricating oil composition.

[0123] Examples of the rust inhibitor that can be used include known rust inhibitors such as petroleum sulfonates, alkylbenzene sulfonates, dinonylnaphthalene sulfonates, alkenyl succinic acid esters, polyhydric alcohol esters, etc. When the lubricating oil composition contains a rust inhibitor, the content thereof is usually 0.005 to 5 mass % based on the total amount of the lubricating oil composition.

[0124] Examples of metal deactivators that can be used other than component (A) include known metal deactivators such as imidazoline, pyrimidine derivatives, mercaptobenzothiazole, benzotriazole and its derivatives, 2-(alkyldithio)benzimidazole, and β-(o-carboxybenzylthio)propionitrile. When the lubricating oil composition contains a metal deactivator other than component (A), the content thereof is typically 0.005 to 1 mass% based on the total amount of the lubricating oil composition.

[0125] The seal swelling agent may be any compound commonly used as a seal swelling agent for lubricating oils, without any particular limitation, and examples thereof include ester-based, sulfur-based, aromatic-based seal swelling agents, etc. For example, known seal swelling agents that cause swelling of elastomer materials, such as alcohols, alkylbenzenes, substituted sulfolane, and mineral oils, may be used. The alcohol-based seal swelling agent is a low-volatility linear alkyl alcohol, and preferred examples thereof include decyl alcohol, tridecyl alcohol, and tetradecyl alcohol. In this specification, if the alcohol-based seal swelling agent also falls under component (E), the content of the alcohol-based seal swelling agent is also counted as the content of component (E). Examples of alkylbenzenes that can be used as seal swelling agents include dodecylbenzene, tetradecylbenzene, dinonylbenzene, and di(2-ethylhexyl)benzene. Examples of the substituted sulfolane that can be used as a seal swelling agent 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 are each a hydrogen atom or a (preferably linear) alkyl group having 7 or less carbon atoms, and preferably R 27 and R 28 one of which is a hydrogen atom and the other (preferably R 28 ) is a hydrogen atom or a methyl group, and 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 swell agents are typically low viscosity mineral oils with high naphthenic or aromatic content. The lubricating oil composition may or may not contain a seal swelling agent, but when the lubricating oil composition contains a seal swelling agent, the content thereof is usually 0.01 to 3.0 mass % based on the total amount of the composition.

[0127] Examples of the antifoaming agent that can be used include known antifoaming agents such as silicone, fluorosilicone, and fluoroalkyl ether. When the lubricating oil composition contains an antifoaming agent, the content thereof is usually 0.0005 to 1 mass% based on the total amount of the lubricating oil composition.

[0128] The demulsifier may be a known demulsifier such as a polyalkylene glycol-based nonionic surfactant. When the lubricating oil composition contains a demulsifier, the content thereof is usually 0.005 to 5 mass% based on the total amount of the lubricating oil composition.

[0129] As the colorant, known colorants 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 mmHg from the viewpoint of enhancing energy saving. 2 / s or less, and from the viewpoint of further improving the wear resistance, seizure resistance, and fatigue life, it is preferably 4.5 mm 2 / s or more, or 5.0 mm 2 / s or more, or 5.5 mm 2 / s or more, and in one embodiment, 4.5 to 6.2 mm 2 / s, or 5.0 to 6.2 mm 2 / s, or 5.5 to 6.2 mm 2 / s.

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

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

[0133] The sulfur content of the lubricating oil composition is 0.050% by mass or less, 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 transmission torque capacity and engagement performance of a wet clutch. Furthermore, the sulfur content of the lubricating oil composition is preferably 0.005% by mass or more, or 0.010% by mass or more, or 0.015% by mass or more, based on the total amount of the composition, from the viewpoint of further improving gear lubrication performance (seizure resistance and fatigue resistance). In one embodiment, the sulfur content of the lubricating oil composition may be 0.005 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 of 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 of 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, and further increasing the transmission torque capacity of a wet clutch. In one embodiment, the phosphorus content of 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 the sulfur content MS (unit: mass%) in the lubricating oil composition to the 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, from the viewpoint of further improving seizure resistance, fatigue resistance, oxidation stability, and the transmission torque capacity of wet clutches, the ratio MS / MP is preferably 0.30 or more, or 0.35 or more, or 0.40 or more. 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] The boron content in the lubricating oil composition is less than 0.030 mass%, preferably 0.029 mass% or less, based on the total amount of the composition, from the viewpoint of improving fatigue resistance. Furthermore, the boron content in the lubricating oil composition is preferably 0.010 mass% or more, based on the total amount of the composition, from the viewpoint of further improving wear resistance, seizure resistance, and the transmission torque capacity of a wet clutch. In one embodiment, the boron content in the lubricating oil composition may be 0.010 mass% or more and less than 0.030 mass%, or 0.010 to 0.029 mass%, based on the total amount of the composition.

[0137] The calcium content of the lubricating oil composition is preferably 0.008% by mass or more, or 0.009% by mass or more, based on the total amount of the composition, in order to further improve wear resistance, seizure resistance, and oxidation stability, as well as the transmission torque capacity and engagement performance of wet clutches. Furthermore, the calcium content of 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, based on the total amount of the composition, in order to facilitate maintaining the ratio MB / MCa of the boron content (MB) to the calcium content (MCa) in the composition (described below) at or below the upper limit. 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, based on the total amount of the composition, in terms of calcium.

[0138] The ratio MB / MCa of the boron content MB (unit: mass%) in the lubricating oil composition to the calcium content MCa (unit: mass%) in the lubricating oil composition is 0.800 or more, preferably 0.805 or more, or 0.810 or more, from the viewpoint of improving wear resistance, seizure resistance, fatigue resistance, and oxidation stability, as well as the transmission torque capacity and engagement performance of a wet clutch. Furthermore, the ratio MB / MCa is 1.200 or less, preferably 1.170 or less, or 1.160 or less, from the viewpoint of improving wear resistance, seizure resistance, fatigue resistance, and oxidation stability, as well as the transmission torque capacity and engagement performance of a 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 the wear resistance, seizure resistance, and fatigue life in the durability stage, the lubricating oil composition preferably has a kinematic viscosity of 5.5 mm at 100°C after irradiating the composition with ultrasonic waves having a frequency of 10 kHz and an oscillator amplitude of 28 μm for 10 hours in a lubricating oil shear stability test in accordance with JPI-5S-29-88. 2 / s or more.

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

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

[0142] <Examples 1 to 12 and Comparative Examples 1 to 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, in the "Base Oil Composition" section, "% by mass" refers to % by mass relative to the total amount of base oil (100% by mass), and in other sections, "% by mass" refers to % by mass relative to the total amount of the lubricating oil composition (100% by mass). Furthermore, "ppm by mass" refers to ppm by mass relative to the total amount of the lubricating oil composition, and the notation "ppm by mass / X" for element X refers to the amount of element X in ppm by mass relative to 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℃): 6.208mm 2 / s, kinematic viscosity (40℃): 33.97mm 2 / s, viscosity index: 133, sulfur content: less than 10 mass ppm, %C P :80.6, %C N :19.4, %C A :0 O-3: API Group II base oil, kinematic viscosity (100℃): 3.12mm 2 / s, kinematic viscosity (40℃): 12.43mm 2 / s, viscosity index: 112, sulfur content: less than 10 mass ppm, %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 Co.), 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 Co.), 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-based 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: Diphenyl hydrogen phosphite (in general formula (4), R 3 =R 4= phenyl group phosphite diester; 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 detergent) C-1: Sulfurized calcium phenate detergent, base number 255 mg KOH / g, Ca content 0.25 mass%, sulfur content 3.5 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 modifier) E-1: Fatty acid amide friction modifier, condensation product of isostearic acid and tetraethylenepentamine, nitrogen content 6.20 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: Dispersion-type poly(meth)acrylate, weight-average molecular weight: 40,000

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

[0151] Other performance additives: seal swelling agent, antifoaming agent (dimethyl silicone, kinematic viscosity (25°C): 160,000mm 2 / s)

[0152] [Table 1]

[0153] [Table 2]

[0154] [Table 3]

[0155] [Table 4]

[0156] (Fast walk test) For each lubricating oil composition, the ultimate non-seizure load (LNSL) was measured at 1800 rpm using a high-speed four-ball test in accordance with JPI-5S-40-93. The results are shown in Tables 1 to 4. A higher LNSL value measured in this test indicates better seizure resistance. The wear resistance of each lubricating oil composition was evaluated using a high-speed four-ball test in accordance with JPI-5S-40-93. The wear scar diameter was measured after 30 minutes of operation at a rotation 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. The smaller the wear scar diameter measured in this test, the better the 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 Method A. At 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. The higher the value of the seizure load measured in this test, the better the seizure resistance.

[0158] (Unisteel Test) For each lubricating oil composition, the rolling fatigue life of a thrust bearing was measured using a Unisteel rolling fatigue tester (a triple-barrel high-temperature rolling fatigue tester (TRF-1000 / 3-01H), manufactured by Tokyo Test Instruments Co., Ltd.) according to the Unisteel test (British Institute of Petroleum method: IP305 / 79). A test bearing was prepared by replacing one raceway of a thrust needle bearing (FNTA-2542C manufactured by NSK) with a flat test piece (material: SUJ2). The time until fatigue damage occurred to either the roller or the test piece was measured under conditions of a load of 7000 N, a surface pressure of 2 GPa, a rotational speed of 1450 rpm, and an oil temperature of 120°C. The vibration acceleration of the test section measured by a vibration accelerometer attached to the Unisteel rolling fatigue tester was 1.5 m / s. 2 It was determined that fatigue damage had occurred when the fatigue life reached 50%. The fatigue life was calculated as the 50% life (L50: the time when the cumulative probability reaches 50%) using a Weibull plot from the time to fatigue damage in 10 repeated tests. The results are shown in Tables 1 to 4. The longer the 50% life measured in this test, the better the fatigue resistance.

[0159] (ISOT oxidation stability test) The oxidation stability of each lubricating oil composition was evaluated by the ISOT test in accordance with JIS K2514. The test was carried out 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. The smaller the increase in acid value after the test, the better the oxidation stability.

[0160] (SAE No. 2 friction test: Evaluation of shift shock index) For each lubricating oil composition, a dynamic friction test was carried out in accordance with JASO M348:2002 using an SAE No. 2 testing machine (manufactured by Shinko Engineering Co., Ltd.). The static friction coefficient μ between the friction plate (NW461E material) and the steel plate after 10,000 cycles was t and the coefficient of dynamic friction μ d The results are shown in Tables 1 to 4. Static friction coefficient μ t The higher the coefficient of dynamic friction μd The higher the value, the higher the engagement performance of the wet clutch.

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

Claims

1. a lubricating base oil comprising one or more mineral base oils, or one or more synthetic base oils, or a combination thereof; (A) one or more thiadiazole compounds; (B) one or more non-sulfur containing phosphorus compounds; (C) one or more calcium-based detergents, including one or more calcium phenate detergents; and (D) one or more succinimide dispersants, including one or more boron-containing succinimide dispersants; and (E) one or more oily agent-based friction modifiers; Contains The sulfur content in the composition is 0.050% by mass or less based on the total amount of the composition, The content of boron in the composition is less than 0.030% by mass based on the total amount of the composition, The kinematic viscosity of the composition at 100°C is 6.2 mm 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 MB (unit: mass%) in the composition to the calcium content MCa (unit: mass%) in the composition is 0.80 to 1.

20.

2. 2. The lubricating oil composition according to claim 1, wherein the content of component (A) is 0.010 to 0.050 mass % in terms of sulfur content based on the total amount of the composition.

3. 3. The lubricating oil composition according to claim 1, wherein the content of component (B) is 0.010 to 0.100 mass % in terms of phosphorus content based on the total amount of the composition.

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

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

6. 3. The lubricating oil composition according to claim 1, wherein the content of component (D) is 0.010 mass % or more and less than 0.030 mass % in terms of boron content, based on the total amount of the composition.

7. 3. The lubricating oil composition according to claim 1 or 2, wherein component (E) contains (E1) 0.10 to 3.00 mass % based on the total amount of the composition of one or more N-acylated nitrogen-containing compounds each 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.

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

9. 3. The lubricating oil composition according to claim 1, further comprising (G) 0.01 to 1.00 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 lubricating base oil has a kinematic viscosity of 4.2 mm at 100 ° C. ２ 3. The lubricating oil composition according to claim 1, wherein the viscosity of the lubricating oil composition is 1 / s or more and the viscosity index is 120 or more.

11. 3. The lubricating oil composition according to claim 1, wherein the lubricating oil composition has a viscosity index of 155 or greater.

12. In a lubricating oil shear stability test in accordance with JPI-5S-29-88, the lubricating oil composition was irradiated with ultrasonic waves having a frequency of 10 kHz and an oscillator amplitude of 28 μm for 10 hours, and the kinematic viscosity of the composition at 100°C was 5.5 mm ２ 3. The lubricating oil composition according to claim 1, wherein the .gamma.-to-.alpha ...beta.

13. 3. The lubricating oil composition according to claim 1, which is used to lubricate a transmission equipped with a wet clutch.

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