CN116323879A - Lubricating oil composition - Google Patents

Abstract

A lubricating oil composition comprising a kinematic viscosity at 40 ℃ of 6.0 to 12.0mm ² A lubricating base oil of/s, 80 mass ppm or more and 2.7 mass% or less in terms of nitrogen component of (A) a succinimide dispersant having a polyisobutenyl group with a number average molecular weight of 800 or more, and 50 to 1300 mass ppm in terms of nitrogen component of (B) a condensation reaction product of an alkyl or alkenyl succinic acid having an alkyl or alkenyl group with a carbon number of 8 to 30 or an anhydride thereof with a polyamine or a modified product thereof, or a combination thereof, wherein the product of the weight average molecular weight of the component (A) and the content (mass%) in terms of the compound is 16,000 or less.

Description

Lubricating oil composition

Technical Field

The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition which can be preferably used for lubricating an automatic transmission and/or an electric engine.

Background Art

As one of the energy-saving measures in gear devices such as transmissions and final reducers, the lowering of the viscosity of lubricating oil can be cited. For example, transmissions and final reducers have gear bearing mechanisms, and by lowering the viscosity of the lubricating oil used, the stirring resistance and drag torque caused by the viscosity resistance of the lubricating oil can be reduced, and the power transmission efficiency can be improved, which makes it possible to improve fuel efficiency.

Prior art literature

Patent Literature

[Patent Document 1] Japanese Patent Application Publication No. 2009-249496

[Patent Document 2] Japanese Patent Application Publication No. 2014-159496

[Patent Document 3] Japanese Patent Application Publication No. 2016-003258

[Patent Document 4] Japanese Patent Application Publication No. 2016-020454

[Patent Document 5] International Publication No. 2020/095968

[Patent Document 6] International Publication No. 2020/095969

[Patent Document 7] International Publication No. 2020/095970

[Patent Document 8] International Publication No. 2020/171188

Summary of the invention

Problem that the invention aims to solve

In recent years, from the perspective of energy efficiency and environmental compatibility, electric vehicles that use electric engines as driving power sources, and hybrid vehicles that use electric engines and internal combustion engines as driving power sources have attracted much attention. Electric engines generate heat as they run, and electric engines contain heat-sensitive parts such as coils and magnets. Therefore, in these cars that use electric engines as driving power sources, a unit for cooling the electric engines is provided. As units for cooling electric engines, air cooling, water cooling, and oil cooling are known. Among these, the oil cooling method is to circulate oil inside the electric engine so that the heating parts in the electric engine (such as coils, cores, magnets, etc.) are in direct contact with the cooling medium (oil), thereby achieving a high cooling effect. In an oil-cooled electric engine, by circulating oil (lubricating oil) inside the electric engine, the electric engine can be lubricated and cooled at the same time. The lubricating oil (electric engine oil) of the electric engine is required to have electrical insulation properties.

Electric motors and transmissions are usually lubricated with different lubricants. If the electric motor and transmission (gear mechanism) can be lubricated with the same lubricant, it will be possible to simplify the lubricant circulation mechanism. However, the electrical insulation of existing transmission oils is insufficient when used for electric motor lubrication. In addition, the durability of existing electric motor oils against oxidation deterioration is insufficient when used for transmission (gear mechanism) lubrication.

For lubricants such as transmission oil and motor oil that are exposed to high temperatures above a certain level, oxidation deterioration is a factor that determines the life of the lubricant. The highly polar components produced by oxidation deterioration of the lubricant are not only easily precipitated as insoluble components, but also reduce the electrical insulation of the lubricant. In addition, as oxidation deterioration progresses, the increase in acid value can also lead to corrosion of metal parts.

Detergents and dispersants are important ingredients that alleviate these problems caused by oxidative deterioration of lubricating oils and improve the long-term effectiveness of lubricating oils. Detergents and dispersants are a concept that includes ashless dispersants and metal-based detergents. Metal-based detergents are metal salts of organic acids that can form micelles in oil (e.g., alkaline earth metal salicylates, alkaline earth metal sulfonates, alkaline earth metal phenolates, etc.), or mixtures of the metal salts and metal bases (e.g., oxides, hydroxides, etc.). Ashless dispersants usually have a polar group (e.g., an amine group, etc.) that interacts with highly polar components in one molecule, and a long-chain alkyl or alkenyl group (e.g., a polyisobutylene group, etc.) that has sufficient oiliness to disperse highly polar components in the oil. Examples of specific compounds used as ashless dispersants include condensation reaction products of alkyl or alkenyl succinic acid or its anhydride and polyamines, Mannich reaction products of alkyl or alkenyl phenols, formaldehyde, and polyamines, and the like. Since the ashless dispersant does not form micelles in oil, in order to ensure the oiliness necessary for the function of the ashless dispersant, an alkyl or alkenyl group with a longer chain than the oily group possessed by the organic acid constituting the metal-based detergent is required. As such an alkyl or alkenyl group, for example, an alkyl or alkenyl group derived from a polyolefin obtained by polymerization of an olefin such as isobutylene (polyisobutylene group) is preferably used. Therefore, the ashless dispersant generally has a larger molecular weight than the metal-based detergent.

If the content of metal-based detergents in lubricating oil is increased, the electrical insulation of new oil tends to be significantly reduced. Therefore, based on the viewpoint of ensuring the electrical insulation required for the lubrication of electric motors, the content of metal-based detergents in lubricating oil is preferably less. In lubricating oils with reduced metal-based detergents or without metal-based detergents, in order to alleviate the problems caused by oxidation and deterioration of lubricating oils and improve long-term effectiveness, it is necessary to increase the content of ashless dispersants. Nevertheless, although ashless dispersants do not reduce the electrical insulation of new oil like metal-based detergents, they are more likely to increase the viscosity of lubricating oils than metal-based detergents. Therefore, based on the viewpoint of improving the energy-saving performance of lubricating oils, it is preferred that the content of ashless dispersants is less.

The present invention is not only a low-viscosity lubricating oil composition with improved energy saving performance, but also aims to provide a lubricating oil composition that has electrical insulation required for lubricating electric motors and can alleviate problems caused by oxidation deterioration in the lubrication of automatic transmissions and electric motors, thereby improving long-term performance.

Technical means of solving problems

The present invention includes the following embodiments [1] to [10].

[1] A lubricating oil composition comprising

(O) a lubricating oil base oil containing one or more mineral oil-based base oils or one or more synthetic base oils or a combination thereof, and having a kinematic viscosity at 40° C. of 6.0 to 12.0 mm ² /s,

(A) a condensation reaction product of polyisobutenylsuccinic acid or its anhydride and polyamine having a polyisobutenyl group with a number average molecular weight of 800 or more, or a modified product thereof, or a combination thereof, in an amount of 80 ppm by mass or more in terms of nitrogen content and 2.7 % by mass or less in terms of compounds, based on the total amount of the composition,

and 50 to 1300 ppm by mass of (B) a condensation reaction product of an alkyl or alkenyl succinic acid or its anhydride having an alkyl or alkenyl group having 8 to 30 carbon atoms and a polyamine, or a modified product thereof, or a combination thereof, in terms of nitrogen content based on the total amount of the composition,

The product of the weight average molecular weight (unit: Da) of the component (A) and the content (unit: mass %) of the component (A) in terms of compound is 16,000 or less.

[2] The lubricating oil composition of [1], which contains (C) one or more calcium carbonate overbased calcium sulfonate detergents or one or more calcium carbonate overbased calcium salicylate detergents, or a combination thereof, in an amount of 10 ppm by mass to less than 100 ppm by mass in terms of calcium based on the total amount of the composition.

[3] The lubricating oil composition according to [1] or [2], comprising (D) one or more amine antioxidants and one or more phenolic antioxidants in a total amount of 0.1 to 3.0 mass % based on the total amount of the composition.

[4] The lubricating oil composition according to any one of [1] to [3], which contains or does not contain (E) one or more phosphorus-containing compounds or one or more sulfur-containing compounds containing at least one sulfur atom with a formal oxidation number of +II or less in one molecule, or a combination thereof, in an amount of 1000 ppm by mass or less in terms of the total content of phosphorus and sulfur components based on the total amount of the composition.

[5] The lubricating oil composition according to any one of [1] to [4], wherein the content A (unit: mass ppm) of the component (A) as a nitrogen component based on the total amount of the composition and the content B (unit: mass ppm) of the component (B) as a nitrogen component based on the total amount of the composition satisfy the relationship represented by the following formula (1).

【Number 1】

B≥max(50,f(A))

[6] The lubricating oil composition according to any one of [1] to [5], which may or may not contain 5.0 mass % or less of (F) one or more polyalkyl (meth)acrylates having a weight average molecular weight of more than 25,000, based on the total amount of the composition.

In this specification, "(meth)acrylate" means "acrylate and/or methacrylate".

[7] The lubricating oil composition according to any one of [1] to [6], which may or may not contain less than 0.1% by mass of one or more polymers having a weight average molecular weight of 25,000 or less based on the total amount of the composition.

[8] The lubricating oil composition according to any one of [1] to [7], which is used for lubrication of an automatic transmission.

[9] The lubricating oil composition according to any one of [1] to [8], which is used for lubricating an electric motor.

[10] A method for lubricating an automatic transmission and an electric engine, comprising supplying the lubricating oil composition described in any one of [1] to [9] to the automatic transmission of an automobile having the automatic transmission and the electric engine, and supplying the lubricating oil composition to the electric engine of the automobile.

Effects of the Invention

The present invention provides a low-viscosity lubricating oil composition with improved energy saving performance, which has the electrical insulation required for lubricating electric motors and can alleviate the problems caused by oxidative deterioration in lubricating automatic transmissions and electric motors to improve long-term performance.

DETAILED DESCRIPTION

The present invention will be described in detail below. It should be noted that, in this specification, unless otherwise specified, the expression "A to B" for numerical values A and B is equivalent to "A or more and B or less. In the case where only numerical value B has a unit in this expression, the unit also applies to numerical value A. In this specification, "or" and "or" mean or unless otherwise specified. In this specification, regarding elements _E1 and _E2 , the expression " _E1 and/or _E2 " is equivalent to " _E1 or _E2 , or a combination thereof", and regarding N elements _E1 , ..., _Ei , ..., _EN (N is an integer greater than 3), the expression " _E1 , ..., and/or _EN " is equivalent to " _E1 , ..., or Ei, _... , or _EN , or a combination thereof" (i is a variable whose values can be all integers satisfying 1＜i＜N.). In addition, the "alkaline earth metal" in this specification also includes magnesium.

It should be noted that, in this specification, unless otherwise specified, the content of each element of calcium, magnesium, zinc, phosphorus, sulfur, boron, barium and molybdenum in the oil is measured based on JIS K0116 by inductively coupled plasma atomic emission spectroscopy (intensity contrast method (internal standard method)). In addition, the content of nitrogen in the oil is measured by chemiluminescence method based on JIS K2609. In addition, the "weight average molecular weight" and "number average molecular weight" in this specification refer to the weight average molecular weight and number average molecular weight converted to standard polystyrene measured by gel permeation chromatography (GPC). The measurement conditions of GPC are as follows.

[GPC measurement conditions]

Equipment: ACQUITY (registered trademark) APC UV RI system manufactured by Waters Corporation

Chromatographic columns: 2 ACQUITY (registered trademark) APC XT900A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation and 1 ACQUITY (registered trademark) APC XT200A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation, connected in series from the upstream side

Column temperature: 40°C

Sample solution: Tetrahydrofuran solution with a sample concentration of 1.0 mass %

Solution injection volume: 20.0μL

Eluent: Tetrahydrofuran

Detection device: Differential refractive index detector

Standard substances: 8 types of standard polystyrene (Agilent EasiCal (registered trademark) PS-1 manufactured by Agilent Technologies) (molecular weights: 2698000, 597500, 290300, 133500, 70500, 30230, 9590, 2970)

When the weight average molecular weight measured under the above conditions is less than 10,000, the column and standard substance are changed to the following conditions and the measurement is performed again.

Chromatographic columns: From the upstream side, one Waters Corporation ACQUITY (registered trademark) APC XT125A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) and two Waters Corporation ACQUITY (registered trademark) APC XT45A (gel particle size 1.7 μm, column size (inner diameter × length) 4.6 mm × 150 mm) were connected in series.

Standard substances: 10 types of standard polystyrene (Agilent EasiCal (registered trademark) PS-1 manufactured by Agilent Technologies) (molecular weight: 30230, 9590, 2970, 890, 786, 682, 578, 474, 370, 266)

＜(O) Lubricant base oil＞

The lubricating oil composition of the present invention (hereinafter also referred to as "lubricating oil composition" or "composition") comprises a lubricating base oil and one or more additives other than the base oil as a main amount. In the lubricating oil composition of the present invention, a lubricating base oil containing one or more mineral base oils or one or more synthetic base oils or a combination thereof and having a kinematic viscosity at 40°C of 6.0 to 12.0 ^mm2 /s (hereinafter referred to as "component (O)") is used as the lubricating base oil.

As the lubricating oil base oil, one or more mineral oil base oils or one or more synthetic base oils, or mixed base oils thereof can be used. In one embodiment, as the lubricating oil base oil, group I base oil (hereinafter also referred to as "API group I base oil"), group II base oil (hereinafter also referred to as "API group II base oil"), group III base oil (hereinafter also referred to as "API group III base oil"), group IV base oil (hereinafter also referred to as "API group IV base oil"), or group V base oil (hereinafter also referred to as "API group V base oil") or mixed base oils thereof can be used. API group I base oil is a mineral oil base oil having a sulfur content greater than 0.03% by mass and/or a saturated content less than 90% by mass, and a viscosity index of 80 or more and less than 120. API group II base oil is a mineral oil base oil having a sulfur content of less than 0.03% by mass, a saturated content of more than 90% by mass, and a viscosity index of more than 80 and less than 120. API Group III base oil is a mineral oil base oil with a sulfur content of less than 0.03% by mass, a saturated content of more than 90% by mass, and a viscosity index of more than 120. API Group IV base oil is an α-polyolefin base oil. API Group V base oil is a base oil other than the above-mentioned Groups I to IV, and ester base oils can be cited as preferred examples. It should be noted that in this specification, the viscosity index refers to the viscosity index measured based on JIS K 2283-2000. In addition, in this specification, the "sulfur content in the lubricating base oil" is measured based on JIS K 2541-2003. In addition, in this specification, the "saturated content in the lubricating base oil" is a value measured based on ASTM D 2007-93.

In one embodiment, as the component (O), one or more API Group II base oils, one or more API Group III base oils, one or more API Group IV base oils, one or more API Group V base oils, or a combination thereof can be preferably used.

Examples of mineral oil-based base oils include paraffinic mineral oils obtained by subjecting lubricating oil fractions obtained by atmospheric distillation and/or vacuum distillation of crude oil to purification by one or more purification treatments selected from solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrofining, 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 by a hydrocracking process.

Preferred examples of the mineral oil-based base oil include base oils obtained by using the base oils (1) to (8) shown below as raw materials, refining the raw material oil and/or the lubricating oil fraction recovered from the raw material oil by a predetermined refining method, and recovering the lubricating oil fraction.

(1) Distillate oil obtained by atmospheric distillation of paraffinic crude oil and/or mixed crude oil

(2) Distillate oil obtained by vacuum distillation of atmospheric distillation residue oil of paraffinic crude oil and/or mixed crude oil (WVGO)

(3) Waxes obtained through a lubricating oil dewaxing process (slack wax, etc.) and/or synthetic waxes obtained through a Fischer-Tropsch (FT) synthesis process, etc. (FT wax, natural gas synthesis (GTL) wax, etc.)

(4) One base oil selected from the base oils (1) to (3), or a mixed oil of two or more base oils selected from the base oils (1) to (3), or a lightly hydrocracked oil thereof, or a mixed oil thereof

(5) A mixed oil of two or more selected from the base oils (1) to (4)

(6) Deasphalted oil (DAO) of base oil (1), (2), (3), (4) or (5)

(7) Mildly hydrocracked oil (MHC) of base oil (6)

(8) A mixed oil of two or more selected from the base oils (1) to (7).

It should be noted that, as the above-mentioned refining method, preferred are hydrorefining such as hydrocracking and hydrofinishing; solvent refining such as furfural solvent extraction; dewaxing such as solvent dewaxing and catalytic dewaxing; clay refining by acid clay, activated clay, etc.; chemical (acid or alkali) washing such as sulfuric acid washing and caustic soda washing, etc. These refining methods may be performed alone or in combination of two or more. In addition, when combining two or more refining methods, the order thereof is not particularly limited and may be appropriately selected.

As the mineral oil-based base oil, the following base oil (9) or (10) obtained by subjecting a base oil selected from the above base oils (1) to (8) or a lubricating oil fraction recovered from the base oil to a predetermined treatment is particularly preferred.

(9) Hydrocracking a base oil selected from the above base oils (1) to (8) or a lubricating oil fraction recovered from the base oil, and subjecting the product or the lubricating oil fraction recovered from the product by distillation or the like to a dewaxing treatment such as solvent dewaxing or catalytic dewaxing, or subjecting the dewaxing treatment to distillation to obtain a hydrocracked base oil

(10) A base oil selected from the above base oils (1) to (8) or a lubricating oil fraction recovered from the base oil is hydroisomerized, and the product or the lubricating oil fraction recovered from the product by distillation or the like is subjected to a dewaxing treatment such as solvent dewaxing or catalytic dewaxing, or the dewaxing treatment is followed by distillation to obtain a hydroisomerized base oil. Preferably, the base oil is produced by a catalytic dewaxing step as the dewaxing step.

When the lubricating base oil of (9) or (10) is obtained, a solvent refining treatment and/or a hydrofinishing treatment step may be further performed as necessary at an appropriate stage.

In addition, the catalyst that can be used for the above-mentioned hydrocracking and hydroisomerization is not particularly limited, and it is preferred to use: a hydrocracking catalyst in which a metal having a hydrogenation ability (for example, one or more metals of Group VIa of the periodic table, metals of Group VIII, etc.) is loaded on a composite oxide having a decomposition activity (for example, silica·alumina, alumina·boria, silica·zirconia, etc.) or a combination of one or more of the composite oxides bonded with a binder as a carrier; or a hydroisomerization catalyst in which at least one metal having a hydrogenation ability among metals of Group VIII is loaded on a carrier including zeolite (for example, ZSM-5, beta zeolite, SAPO-11, etc.). The hydrocracking catalyst and the hydroisomerization catalyst can be used in combination by stacking or mixing.

The reaction conditions for hydrocracking and hydroisomerization are not particularly limited, but preferably the hydrogen partial pressure is 0.1 to 20 MPa, the average reaction temperature is 150 to 450°C, the LHSV is 0.1 to 3.0 hr ^-1 , and the hydrogen/oil ratio is 50 to 20,000 scf/b.

From the viewpoint of further improving the viscosity-temperature characteristics and fuel efficiency of the composition, the % _CP of the mineral oil-based base oil is preferably 60 or more, more preferably 65 or more. From the viewpoint of improving the solubility of the additive, it is preferably 99 or less, more preferably 95 or less, and further preferably 94 or less. In one embodiment, it can be 60 to 99, 60 to 95, 65 to 95, or 65 to 94.

From the viewpoint of further improving the viscosity-temperature characteristics and fuel efficiency of the composition, the % _CA of the mineral oil-based base oil is preferably 2 or less, more preferably 1 or less, further preferably 0.8 or less, and particularly preferably 0.5 or less.

From the viewpoint of improving the solubility of additives, the % _CN of the mineral oil-based base oil is preferably 1 or more, more preferably 4 or more. From the viewpoint of further improving the viscosity-temperature characteristics and fuel efficiency of the composition, it is preferably 40 or less, more preferably 35 or less. In one embodiment, it can be 1 to 40 or 4 to 35.

In the present specification, % _CP , % _CN and % _CA respectively mean the percentage of the number of paraffinic carbon atoms relative to the total number of carbon atoms, the percentage of the number of cycloparaffinic carbon atoms relative to the total number of carbon atoms, and the percentage of the number of aromatic carbon atoms relative to the total number of carbon atoms determined by the method (ndM ring analysis) according to ASTM D 3238-85. That is, the preferred ranges of the above % _CP , % _CN and % _CA are based on the values determined by the above methods. For example, even for a lubricating base oil containing no cycloparaffin components, the % _CN determined by the above method may show a value exceeding 0.

The content of saturated components in the mineral oil-based base oil is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more, based on the total amount of the base oil, from the viewpoint of improving the viscosity-temperature characteristics of the composition. It should be noted that the saturated components in this specification refer to values measured in accordance with ASTM D 2007-93.

In addition, as a separation method for saturated fractions, similar methods that can obtain the same results can be used. For example, in addition to the method described in ASTM D 2007-93, there can also be mentioned the method described in ASTM D 2425-93, the method described in ASTM D 2549-91, a method via high performance liquid chromatography (HPLC), or a method obtained by improving these methods.

The aromatic component in the mineral oil 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, and in one embodiment can be 0.1% by mass or more. By making the content of the aromatic component below the above upper limit, the low-temperature viscosity characteristics and viscosity-temperature characteristics in the new oil state can be improved, and the fuel economy can be further improved. At the same time, the evaporation loss of the lubricating oil can be further reduced, and the consumption of the lubricating oil can be further reduced. In addition, when the additive is mixed into the lubricating oil base oil, the effect of the additive can be effectively exerted. In addition, the lubricating oil base oil can also be a base oil that does not contain aromatic components, but by making the content of the aromatic component above the above lower limit, the solubility of the additive can be further improved.

It should be noted that the aromatic component in this specification refers to the value measured according to ASTM D 2007-93. The aromatic component generally includes anthracene, phenanthrene and their alkylated products in addition to alkylbenzenes and alkylnaphthalenes, and further includes compounds formed by condensing four or more benzene rings, pyridines, quinolines, phenols, naphthols and other aromatic compounds having heteroatoms.

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

Preferred examples of API Group V base oils include ester 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.); polycarboxylic acid esters (e.g., trimellitic acid esters, etc.); polyol esters (e.g., trimethylolpropane octanoate, trimethylolpropane nonanoate, pentaerythritol-2-ethylhexanoate, pentaerythritol nonanoate, etc.). Other examples of API Group V base oils include aromatic synthetic base oils such as alkylbenzenes, alkylnaphthalenes, polyoxyalkylene glycols, dialkyldiphenyl ethers, and polyphenylene ethers.

The kinematic viscosity at 40°C of the lubricating base oil (total base oil) is 6.0 mm ^{2 /s or more, preferably 6.5 mm 2 /} s or more, and more preferably 7.0 mm ² /s or more from the viewpoint of improving the electrical insulation of the new oil and from the viewpoint of forming an oil film sufficiently at the lubricating position to improve the wear resistance. In addition, from the viewpoint of fuel efficiency and the low-temperature viscosity characteristics of the lubricating oil composition, it is 12.0 mm ² /s or less, and in one embodiment, it may be 6.0 to 12.0 mm ² /s, 6.5 to 12.0 mm ² /s, or 7.0 to 12.0 mm ² /s. It should be noted that the "kinematic viscosity at 40°C" in this specification refers to the kinematic viscosity at 40°C measured using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument Co., Ltd.) as a measuring device in accordance with JIS K2283-2000.

From the viewpoint of further improving the electrical insulation of the new oil and from the viewpoint of forming an oil film sufficiently at the lubricating position to further improve the wear resistance, the kinematic viscosity at 100°C of the lubricating base oil (total base oil) is preferably 1.9 mm ² /s or more, more preferably 2.0 mm ² /s or more, and even more preferably 2.1 mm ² /s or more, and from the viewpoint of further improving the fuel efficiency, it is preferably 3.5 mm ² /s or less, more preferably 3.4 mm ² /s or less, and even more preferably 3.3 mm ² /s or less, and in one embodiment, it may be 1.9 to 3.5 mm ² /s, or 2.0 to 3.4 mm ² /s, or 2.1 to 3.3 mm ² /s. It should be noted that the "kinematic viscosity at 100°C" in this specification refers to the kinematic viscosity at 100°C measured using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument Co., Ltd.) as a measuring device in accordance with JIS K 2283-2000.

From the viewpoint of improving the viscosity-temperature characteristics of the composition and further improving the fuel efficiency and wear resistance, the viscosity index of the lubricating base oil (total base oil) is preferably 100 or more, more preferably 105 or more, further preferably 110 or more, particularly preferably 115 or more, and most preferably 120 or more. It should be noted that the viscosity index in this specification refers to a viscosity index measured using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument Co., Ltd.) as a measuring device based on JIS K 2283-2000.

From the viewpoint of the 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, further preferably -15°C or lower, particularly preferably -17.5°C or lower, and most preferably -20.0°C or lower. In addition, the pour point in this specification means the pour point measured in accordance with JIS K2269-1987.

The content of sulfur in the base oil depends on the sulfur content of its raw material. For example, when using a substantially sulfur-free raw material such as a synthetic wax component obtained by a Fischer-Tropsch reaction, a substantially sulfur-free base oil can be obtained. In addition, when using sulfur-containing raw materials such as slack wax obtained through the refining process of the base oil and microcrystalline wax obtained in the refined wax process, the sulfur content in the obtained base oil is usually more than 100 mass ppm. The sulfur content in the lubricating base oil (total base oil) is usually less than 0.03 mass%, and based on the viewpoint of oxidation stability, it is preferably less than 0.01 mass%. It should be noted that the content of sulfur in the base oil in this specification refers to the sulfur amount measured based on JIS K 2541-2003.

As long as the kinematic viscosity of the lubricating base oil as a whole (total base oil) at 40° C. is 6.0 to 12.0 mm ² /s, the lubricating base oil may be composed of a single base oil component or may contain a plurality of base oil components.

In one embodiment, the lubricating base oil may contain 80 to 100% by mass, or 90 to 100% by mass, or 90 to 99% by mass, or 95 to 99% by mass 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, based on the total amount of the base oil. In one embodiment, the lubricating base oil may contain 80 to 100% by mass, or 90 to 100% by mass, or 90 to 99% by mass, or 95 to 99% by mass of one or more API Group III base oils, or one or more API Group IV base oils, or a combination thereof, based on the total amount of the base oil. The lubricating base oil may contain or may not contain an API Group V base oil. In one embodiment, based on the viewpoint of improving oxidation stability, the content of one or more API Group V base oils in the lubricating base oil is preferably 0 to 20% by mass or 0 to 10% by mass based on the total amount of the base oil, and further, based on the viewpoint of improving fatigue resistance, it may be 1 to 10% by mass, or 1 to 5% by mass. The lubricating base oil may contain or not contain an API Group IV base oil. In one embodiment, the content of one or more API Group IV base oils in the lubricating base oil may be 0 to 60 mass %, or 0 to 50 mass %, or 1 to 60 mass %, or 1 to 50 mass % based on the total amount of the base oil.

The content of the lubricating base oil (total base oil) in the lubricating oil composition is 60% by mass or more, preferably 60 to 98.5% by mass, more preferably 70 to 98.5% by mass, and in one embodiment, 75 to 97% by mass, based on the total amount of the lubricating oil composition.

<(A) First succinimide compound>

The lubricating oil composition of the present invention contains 80 mass ppm or more of nitrogen content and 2.7 mass % or less of compounds, based on the total amount of the composition, of a condensation reaction product of polyisobutenyl succinic acid or its anhydride and polyamine having a polyisobutenyl group with a number average molecular weight of 800 or more, or a modified product thereof, or a combination thereof (hereinafter also referred to as "component (A)"). The condensation reaction product (condensation product) is polyisobutenyl succinimide, which can be represented by the following general formula (2) or (3). Examples of the modified product are described below.

【Chemistry 1】

In the general formula (2), ^R1 represents a polyisobutylene group having a number average molecular weight of 800 or more, and a represents an integer of 1 to 10, preferably 2 to 6. In a typical embodiment, the compound represented by the general formula (2) is obtained as a mixture of compounds having different a. In one embodiment, from the viewpoint of solubility in the base oil, the number of carbon atoms of ^R1 is preferably 40 or more, more preferably 60 or more, and from the viewpoint of low temperature fluidity of the composition, it is preferably 400 or less, more preferably 350 or less, and further preferably 250 or less, and in one embodiment, it may be 40 to 400, or 60 to 350, or 60 to 250.

In the general formula (3), ^R2 and ^R3 each independently represent a polyisobutylene group having a number average molecular weight of 800 or more, and may be a combination of different groups. In addition, b represents an integer of 0 to 15, preferably 1 to 13, and more preferably 1 to 11. In a typical embodiment, the compound represented by the general formula (3) is obtained as a mixture of compounds having different b. In one embodiment, from the viewpoint of solubility in the base oil, the number of carbon atoms of ^R2 and ^R3 is preferably 40 or more, more preferably 60 or more, and from the viewpoint of low temperature fluidity of the composition, it is preferably 400 or less, more preferably 350 or less, and further preferably 250 or less. In one embodiment, it may be 40 to 400, or 60 to 350, or 60 to 250.

The polyisobutenyl groups (R ¹ to R ³ ) in the component (A) are branched alkyl or alkenyl groups derived from an oligomer of isobutylene (polyisobutylene). Polyisobutenyl succinic anhydride can be obtained, for example, by reacting polyisobutylene having a C=C double bond with maleic anhydride at 100 to 200° C. The polyisobutenyl groups in the polyisobutenyl succinic anhydride obtained by the reaction are alkenyl groups having a C=C double bond. By further subjecting the alkenyl succinic anhydride to a hydrogenation reaction, polyisobutenyl succinic anhydride in which the polyisobutenyl groups are in the form of an alkyl group can be obtained.

From the viewpoint of improving oil solubility, the number average molecular weight of the polyisobutene groups (R ¹ to R ³ ) in the component (A) is 800 or more, preferably 900 or more, and from the viewpoint of improving low temperature fluidity of the lubricating oil, it is preferably 3500 or less, and in one embodiment, it may be 800 to 3500 or 900 to 3500. The number average molecular weight Mn ^PIB of the polyisobutene groups in the component (A) can be calculated by the following formula (4) based on the number average molecular weight Mn ^SA of the corresponding polyisobutenyl succinic acid.

Mn ^PIB = Mn ^SA -117.08…(4)

In this specification, the number average molecular weight of polyisobutenyl succinic acid refers to the number average molecular weight based on standard polystyrene measured by gel permeation chromatography (GPC), and the determination method thereof is as described above. When a certain component (A) is given, the number average molecular weight of the polyisobutenyl group in the component (A) can be determined by the following steps.

(1) a step of hydrolyzing component (A) into polyisobutenyl succinic acid and polyamine by reacting component (A) (e.g., 100 mg) in an organic solvent (e.g., 0.5 ml of methanol) with water and a strong base (e.g., 5 ml of a 6N sodium hydroxide solution) (e.g., at 160° C. for 5 hours);

(2) adding a strong acid (e.g. 6N hydrochloric acid) to the mixture after the reaction in (1) to make the solution acidic, and then extracting with a hydrophobic organic solvent (e.g. hexane, toluene, etc.);

(3) a step of washing the organic phase obtained in (2) with an acidic aqueous solution (e.g., dilute hydrochloric acid, etc.) to remove the polyamine and its base (if any) from the organic phase to obtain an organic solvent solution of polyisobutenyl succinic acid;

(4) a step of measuring the number average molecular weight Mn ^SA of the polyisobutenyl succinic acid obtained in (3) by GPC;

(5) A step of calculating the number average molecular weight Mn ^PIB of polyisobutenyl groups by the above formula (4) based on the number average molecular weight Mn ^SA of the polyisobutenyl succinic acid obtained in (4).

The polyisobutylene succinimide includes monosuccinimide represented by the general formula (2) in which only one end of the polyamine chain is imidized, and bissuccinimide represented by the general formula (3) in which both ends of the polyamine chain are imidized. The lubricating oil composition may contain either monosuccinimide or bissuccinimide, or a mixture thereof. The content of bissuccinimide or a modified product thereof in component (A) is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, based on the total amount (100% by mass) of component (A).

As component (A), the above condensation product (i.e., non-modified succinimide) can be used directly, or the condensation product can be used by changing it to a modified product (derivative) described later. The condensation product of polyisobutenyl succinic acid or its anhydride and polyamine can be a bis-succinimide in which both ends of the polyamine chain are imidized (see general formula (3).), or a mono-succinimide in which only one end of the polyamine chain is imidized (see general formula (2).), or a mixture of these. Examples of polyamines include polyethylene polyamines having 3 to 17 nitrogen atoms, such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, heptaethyleneoctamine, octaethylenenonamine, nonaethylenedecamine, decaethyleneundecamine, undecaethylenedodecamine, dodecaethylenetridecamine, tridecaethylenetetradecamine, tetradecaethylenepentadecanamine, pentaethylenehexadecamine, and hexadeceneethyleneheptadecamine, and mixtures thereof. Polyamine raw materials containing one or more selected from these can be preferably used. In one embodiment, polyamine raw materials containing one or more polyethylene polyamines having 3 to 17 nitrogen atoms, or 3 to 15, or 3 to 13 nitrogen atoms can be preferably used. In another embodiment, polyamine raw materials containing one or more polyethylene polyamines having 3 to 11 nitrogen atoms, or 3 to 7 nitrogen atoms can be preferably used. It should be noted that commercially available polyethylene polyamines are generally mixtures of two or more polyethylene polyamines having consecutive nitrogen atoms, and such polyethylene polyamine mixtures can also be preferably used as polyamine raw materials when manufacturing component (A). In addition, although the above general formulas (2) and (3) represent the structure of the condensation reaction product of polyisobutenyl succinic acid or its anhydride and linear polyethylene polyamine, commercially available polyethylene polyamines having 4 or more nitrogen atoms generally contain branched polyethylene polyamines having the same number of nitrogen atoms as structural isomers in addition to linear polyethylene polyamines. The common point between branched polyethylene polyamines and linear polyethylene polyamines is that each group of two adjacent amine groups is connected by an ethylene group. Compared with linear polyethylene polyamines having n nitrogen atoms (n is an integer greater than 2) having 2 primary amine groups and n-2 secondary amine groups, branched polyethylene polyamines having k (k is an integer greater than 1 and less than n-3) branches having n nitrogen atoms have 2+k primary amine groups, n-2-2k secondary amine groups, and k tertiary amine groups. A polyethylene polyamine mixture containing such branched structural isomers can also be preferably used as a polyamine raw material when producing component (A). The condensation reaction product of such branched polyethylene polyamine and polyisobutenyl succinic acid or its anhydride and its modified product are also included in component (A). It should be noted that the general formulas (2) and (3) represent succinimide in which one or two primary amine groups are imidized, but in the condensation reaction of a branched polyethylene polyamine having k branches and polyisobutenyl succinic acid or its anhydride, a maximum of 2+k primary amine groups can be imidized. Such condensation reaction products (succinimide compounds) in which three or more primary amine groups are imidized and their modified products are also included in component (A). The polyamine raw material may further contain ethylenediamine or may not contain it. From the viewpoint of improving the performance of the condensation product or its modified product as a dispersant, the content of ethylenediamine in the polyamine raw material is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, based on the total amount of polyamine. The succinimide obtained as a condensation reaction product of a mixture of polyisobutenyl succinic acid or its anhydride and two or more polyamines is a mixture containing two or more compounds having different a or b in the general formula (2) or (3). The condensation reaction of polyisobutenyl succinic acid or its anhydride and polyamine can be carried out, for example, in an organic solvent (for example, toluene) that forms an azeotropic mixture with water. That is, the condensation reaction product can be easily obtained by removing water generated as the condensation reaction proceeds with the solvent while reflux stirring. The reaction molar ratio in the condensation reaction of polyisobutenyl succinic acid or its anhydride and polyamine can be, for example, polyisobutenyl succinic acid or its anhydride:polyamine=1:10 to 10:1, or 1:5 to 5:1.

The weight average molecular weight of the component (A) is preferably 1,000 to 20,000, more preferably 2,000 to 20,000, further preferably 3,000 to 15,000, and in one embodiment, may be 4,000 to 15,000.

Examples of modified products (modified compounds, derivatives) of polyisobutenyl succinimide include (i) products modified by oxygen-containing organic compounds, (ii) products modified by boric acid, (iii) products modified by phosphoric acid, (iv) products modified by sulfur, and (v) products modified by a combination of two or more of these.

(i) The modified product via an oxygen-containing organic compound is a modified compound obtained by reacting the above-mentioned polyisobutylene 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 oxyalkylene or hydroxy (poly)oxyalkylene carbonate having 2 to 6 carbon atoms, so that part or all of the remaining amino groups and/or imine groups are neutralized or amidated.

(ii) The boric acid-modified product is a modified compound obtained by reacting boric acid with the above-mentioned polyisobutylene succinimide to neutralize or amidate a part or all of the remaining amine groups and/or imine groups.

(iii) The phosphoric acid-modified product is a modified compound obtained by reacting phosphoric acid with the above-mentioned polyisobutylene succinimide to neutralize or amidate a part or all of the remaining amine groups and/or imine groups.

(iv) The sulfur-modified product is a modified compound obtained by reacting the above-mentioned polyisobutenyl succinimide with a sulfur compound.

(v) The modified compound obtained by a combination of two or more modifications can be obtained by subjecting the polyisobutenyl succinimide to a combination of two or more modifications selected from the group consisting of modification with an oxygen-containing organic compound, boric acid modification, phosphoric acid modification, and sulfur modification.

Among the modified products (derivatives) of (i) to (v), boric acid-modified compounds, particularly boric acid-modified products of bis-polyisobutenyl succinimide, can be preferably used.

From the viewpoint of improving the electrical insulation of the composition after oxidative degradation and reducing the increase in the acid value of the composition after oxidative degradation, the content of the component (A) in the lubricating oil composition is 80 mass ppm or more, preferably 100 mass ppm or more, as a nitrogen component based on the total amount of the composition. From the viewpoint of reducing the viscosity of the composition and improving fuel efficiency, the content of the component (A) in the lubricating oil composition is 2.7 mass % or less, preferably 2.5 mass % or less, as a whole compound based on the total amount of the composition. In one embodiment, it can be 2.3 mass % or less.

From the viewpoint of reducing the viscosity of the composition and improving fuel efficiency, the product of the weight average molecular weight (unit: Da, i.e., g/mol) of the component (A) and the content (unit: mass %) of the component (A) in the lubricating oil composition based on the total compound is 16,000 or less, preferably 15,000 or less, and in one embodiment may be 14,000 or less. When the component (A) is composed of a plurality of components, the product is calculated using the weight average molecular weight (Da) based on the total component (A) and the content (mass %) of the total component (A).

<(B) Second succinimide compound>

The lubricating oil composition of the present invention comprises a condensation reaction product of an alkyl or alkenyl succinic acid or its anhydride having an alkyl or alkenyl group with 8 to 30 carbon atoms and a polyamine, or a modified product thereof, or a combination thereof (hereinafter also referred to as "component (B)"). The condensation reaction product (condensation product) is an alkyl or alkenyl succinimide, which can be represented by the following general formula (5) or (6).

【Chemistry 2】

In the general formulae (5) and (6), ^R4 to ^R6 each independently represent an alkyl or alkenyl group having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms, and in one embodiment, 12 to 18 carbon atoms. ^R7 and ^R8 each independently represent an alkylene group having 1 to 4 carbon atoms, preferably an alkylene group having 2 to 3 carbon atoms, and particularly preferably an ethylene group. c represents an integer of 1 to 7, preferably 1 to 6, more preferably 1 to 5, and even more preferably 1 to 4. d represents an integer of 1 to 7, preferably 1 to 4, and even more preferably 1 to 3.

The component (B) is a condensation reaction product (condensation product) obtained by reacting an alkyl or alkenyl succinic acid or its anhydride having an alkyl or alkenyl group with 8 to 30 carbon atoms, preferably 12 to 28 carbon atoms, with a polyamine. As the component (B), the condensation product (i.e., unmodified succinimide) can be used directly, or the condensation product can be converted into a modified product (derivative) described below. The condensation product of the alkyl or alkenyl succinic acid or its anhydride and the polyamine can be a bis-succinimide in which both ends of the polyamine chain are imidized (see general formula (6)), a mono-succinimide in which only one end of the polyamine chain is imidized (see general formula (5)), or a mixture of these. Examples of polyamines include polyethylene polyamines having 3 to 9 nitrogen atoms, such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexethyleneheptamine, heptaethyleneoctamine, and octaethylenenonamine, and mixtures thereof. Polyamine raw materials containing one or more selected from these can be preferably used. In one embodiment, polyamine raw materials containing one or more polyethylene polyamines having 3 to 9 nitrogen atoms, or 3 to 6, or 3 to 5 nitrogen atoms can be preferably used. In another embodiment, polyamine raw materials containing one or more polyethylene polyamines or ethylenediamines having 3 to 8 nitrogen atoms, or 3 to 7, or 3 to 6, or 3 to 5 nitrogen atoms, or combinations thereof can be preferably used. It should be noted that commercially available polyethylene polyamines are generally mixtures of two or more polyethylene polyamines having consecutive nitrogen atoms, and such polyethylene polyamine mixtures can also be preferably used as polyamine raw materials when manufacturing component (B). In addition, the above general formulas (5) and (6) represent the structure of the condensation reaction product of alkyl or alkenyl succinic acid or its anhydride and linear polyethylene polyamine. As described above with respect to component (A), commercially available polyethylene polyamine having 4 or more nitrogen atoms may generally contain branched polyethylene polyamine having the same number of nitrogen atoms as a structural isomer in addition to linear polyethylene polyamine. A polyethylene polyamine mixture containing such branched structural isomers may also be preferably used as a polyamine raw material when manufacturing component (B). The condensation reaction product of such branched polyethylene polyamine and alkyl or alkenyl succinic acid or its anhydride and its modified product are also included in component (B). It should be noted that the general formulas (5) and (6) represent succinimide in which one or two primary amine groups are imidized, but in the condensation reaction of a branched polyethylene polyamine having k branches with alkyl or alkenyl succinic acid or its anhydride, up to 2+k primary amine groups may be imidized. The condensation reaction product (succinimide compound) in which three or more primary amine groups are imidized and its modified product are also included in the (B) component. The polyamine raw material may or may not contain ethylenediamine. Based on the viewpoint of improving the performance of the condensation product or its modified product as a friction modifier and improving the oxidation degradation resistance, the content of ethylenediamine in the polyamine raw material is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, based on the total amount of polyamine. The succinimide obtained as a condensation reaction product of a mixture of an alkyl or alkenyl succinic acid or its anhydride and two or more polyamines is a mixture of two or more compounds having different c or d in the general formula (5) or (6). The condensation reaction of the alkyl or alkenyl succinic acid or its anhydride and the polyamine can be carried out in an organic solvent (such as toluene) that forms an azeotropic mixture with water. That is, the solution of the mixture of alkyl or alkenyl succinic acid or its anhydride and polyamine is stirred under reflux while removing water generated with the progress of the condensation reaction by azeotropic removal with the solvent, so that the condensation reaction product can be easily obtained. The reaction molar ratio in the condensation reaction of alkyl or alkenyl succinic acid or its anhydride and polyamine can be, for example, alkyl or alkenyl succinic acid or its anhydride:polyamine=1:10 to 10:1, or 1:5 to 5:1.

Examples of modified products (derivatives) of succinimide compounds that can be used as component (B) include modified products obtained by reacting the above-mentioned succinimide compounds (condensation reaction products) with boric acid, phosphoric acid, carboxylic acids having 1 to 20 carbon atoms, and one or more compounds selected from sulfur-containing compounds. Among these, boric acid modified products can be preferably used.

Highly polar components such as component (B) and metallic detergents tend to reduce the electrical insulation of new oil and compositions that have undergone oxidation and deterioration. However, the present inventors have found that by using components (A) and (B) together within their respective prescribed content ranges, it is possible to reduce the content of component (A) and improve energy saving, while reducing the increase in acid value of oxidatively deteriorated oil without significantly reducing the electrical insulation of new oil and compositions that have undergone oxidation and deterioration.

The content of the component (B) in the lubricating oil composition is 50 ppm by mass or more as a nitrogen component based on the total amount of the composition from the viewpoint of reducing the increase in the acid value of the oxidatively degraded oil, and is 1300 ppm by mass or less from the viewpoint of improving the electrical insulation properties of the oxidatively degraded oil.

Based on the viewpoint that reducing the content of component (A) improves energy saving performance while reducing the increase in acid value of oxidatively deteriorated oil without significantly losing the electrical insulation of the new oil and the composition after oxidative deterioration, the content A (unit: mass ppm) of component (A) as a nitrogen component based on the total amount of the composition and the content B (unit: mass ppm) of component (B) as a nitrogen component based on the total amount of the composition preferably satisfy the relationship represented by the following formula (1). The function max in the following formula (1) is a function of the maximum value of the independent variable. That is, when f(A)>50, max(50, f(A))=f(A), when f(A)<50, max(50, f(A))=50, and when f(A)=50, max(50, f(A))=50.

【Number 2】

B≥max 50,f(A))

＜(C) Calcium-based cleaners＞

In a preferred embodiment, the lubricating oil composition may further contain one or more calcium carbonate overbased calcium sulfonate detergents (hereinafter also referred to as "(C1) component") or one or more calcium carbonate overbased calcium salicylate detergents (hereinafter also referred to as "(C2) component"), or a combination thereof (hereinafter also referred to as "(C) component".). The (C) component may contain only the (C1) component, only the (C2) component, or both the (C1) component and the (C2) component.

Preferred examples of the (C1) calcium carbonate overbased calcium sulfonate detergent include overbased salts of calcium salts of alkyl aromatic sulfonic acids obtained by sulfonating alkyl aromatic compounds. The weight average molecular weight of the alkyl aromatic compound is preferably 300 to 1500, more preferably 400 to 1300.

As examples of alkyl aromatic sulfonic acids, so-called petroleum sulfonic acids and synthetic sulfonic acids can be cited. As examples of petroleum sulfonic acids described herein, sulfonated products of alkyl aromatic compounds in the lubricating oil fraction of mineral oil and by-products when manufacturing white oil, namely petroleum sulfonic acid (mahogany acid), etc. can be cited. In addition, as an example of synthetic sulfonic acid, by-product recovery in the manufacturing equipment of alkylbenzene, a raw material for detergent, or the product after sulfonation of alkylbenzene with a linear or branched alkyl group obtained by alkylation of benzene by polyolefin can be cited. As other examples of synthetic sulfonic acids, products of sulfonation of alkylnaphthalenes such as dinonylnaphthalene can be cited. In addition, as the sulfonating agent for these alkyl aromatic compounds during sulfonation, there is no particular restriction, for example, oleum or anhydrous sulfuric acid can be used.

(C2) Calcium carbonate overbased calcium salicylate detergent is an overbased salt of calcium salicylate. Preferred examples of calcium salicylate include calcium salicylate represented by the following general formula (7).

【Chemistry 3】

In the general formula (7), R ⁹ each independently represents an alkyl group or alkenyl group having 14 to 30 carbon atoms, and e represents 1 or 2, preferably 1. It should be noted that when e=2, R ⁹ may be a combination of different groups.

The method for producing calcium salicylate is not particularly limited, and a known method for producing monoalkyl salicylate can be used. For example, phenol is used as a starting material and alkylated with an olefin, followed by carboxylation with carbon dioxide or the like to obtain monoalkyl salicylic acid, or salicylic acid is used as a starting material and alkylated with an equivalent amount of the above olefin to obtain monoalkyl salicylic acid, and these are reacted with a calcium base such as calcium oxide or hydroxide, or these monoalkyl salicylic acids are first formed into an alkali metal salt such as a sodium salt or potassium salt and then metal exchanged with a calcium salt, thereby obtaining calcium salicylate.

The method for obtaining calcium carbonate overbased calcium sulfonate or calcium salicylate is not particularly limited. For example, calcium carbonate overbased calcium sulfonate or calcium salicylate can be obtained by reacting calcium sulfonate or calcium salicylate with a base such as calcium hydroxide in the presence of carbon dioxide.

Based on the viewpoint of improving wear resistance, seizure resistance and the transmission torque capacity of the wet clutch, the base value of the component (C1) and the component (C2) is preferably 200 mgKOH/g or more, more preferably 250 mgKOH/g or more, and based on the same viewpoint, it is preferably 600 mgKOH/g or less, more preferably 550 mgKOH/g or less, and in one embodiment, it can be 200 to 600 mgKOH/g, or 250 to 550 mgKOH/g. It should be noted that when the component (C1) contains two or more calcium carbonate high-based calcium sulfonate detergents, the base value of each calcium carbonate high-based calcium sulfonate detergent is preferably within the above range. Similarly, when the component (C2) contains two or more calcium carbonate high-based calcium salicylate detergents, the base value of each calcium carbonate high-based calcium salicylate detergent is preferably within the above range. It should be noted that the base value in this specification refers to the base value measured based on the JIS K2501 perchloric acid method. In addition, metal-based detergents are generally obtained by reaction in a diluent such as a solvent or a lubricating base oil. For this reason, metal-based detergents are commercially circulated in a state diluted with a diluent such as a lubricating base oil. In this specification, the base value of a metal-based detergent refers to the base value in a state containing a diluent.

When the lubricating oil composition contains component (C), the content thereof (when component (C) contains two or more detergents, the content is the total content) is preferably less than 100 mass ppm, more preferably 95 mass ppm or less, or 90 mass ppm or less, and in one embodiment may be 80 mass ppm or less in terms of calcium content based on the total amount of the composition, from the viewpoint of further improving the electrical insulation and fuel efficiency of the new oil and improving the fatigue resistance. In addition, from the viewpoint of improving the wear resistance, seizure resistance, fatigue resistance and the transmission torque capacity of the wet clutch, it is preferably 10 mass ppm or more, more preferably 15 mass ppm or more, and in one embodiment it is 20 mass ppm or more. In one embodiment, it may be 10 mass ppm or more and less than 100 mass ppm, or 10 to 95 mass ppm, or 15 to 90 mass ppm, or 20 to 80 mass ppm.

In the field of lubricating oils, metal salts of organic acids (e.g., alkali metal or alkaline earth metal alkyl salicylates, alkali metal or alkaline earth metal alkylbenzene sulfonates, and alkali metal or alkaline earth metal alkylphenol salts) that can form micelles in base oils or mixtures of the organic acid metal salts and alkaline metal salts (e.g., hydroxides, carbonates, borates, etc. of alkali metal or alkaline earth metals constituting the organic acid metal salts) are generally used as metal detergents. Such organic acids generally have in one molecule at least one polar group having Bronsted acidity (e.g., carboxyl, sulfonic, phenolic hydroxyl, etc.) that can form a salt with a metal base (typically, a metal oxide and/or a metal hydroxide), and at least one lipophilic group such as a straight-chain or branched alkyl group (e.g., a straight-chain or branched alkyl group having more than 6 carbon atoms, etc.). The soap group of the metal-based detergent refers to the conjugate base of the organic acid constituting the soap component of the metal-based detergent (for example, alkyl salicylate anion in salicylate detergents, alkylbenzene sulfonate anion in sulfonate detergents, and alkylphenol anion in phenate detergents).

The lubricating oil composition of the present invention may further contain one or more metal-based detergents other than component (C), or may not contain any of them. However, from the viewpoint of further improving the electrical insulation, fuel efficiency and fatigue resistance of the new oil, the total content of all metal-based detergents including component (C) in the lubricating oil composition is preferably less than 100 mass ppm, more preferably 95 mass ppm or less, or 90 mass ppm or less, and in one embodiment, 80 mass ppm or less in terms of the metal amount based on the total amount of the composition. From the viewpoint of further improving the seizure resistance, fatigue resistance and the transmission torque capacity of the wet clutch, and from the viewpoint of further improving the wear resistance, it is preferably 10 mass ppm or more, and in one embodiment, 20 mass ppm or more. In one embodiment, it may be 10 mass ppm or more and less than 100 mass ppm, or 10 to 95 mass ppm, or 15 to 95 mass ppm, or 20 to 80 mass ppm. In one embodiment, the lubricating oil composition of the present invention may be a lubricating oil composition that does not contain a metal-based detergent other than component (C).

＜(D) Antioxidant＞

In a preferred embodiment, the lubricating oil composition may further contain one or more amine antioxidants (hereinafter also referred to as "component (D1)") and one or more phenolic antioxidants (hereinafter also referred to as "component (D2)") as antioxidants (hereinafter also referred to as "component (D)").

Examples of the component (D1) include aromatic amine antioxidants and hindered amine antioxidants. Examples of aromatic amine antioxidants include aromatic primary amine compounds such as alkylated α-naphthylamine, and aromatic secondary amine compounds such as alkylated diphenylamine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, and phenyl-β-naphthylamine. As aromatic amine antioxidants, alkylated diphenylamine, alkylated phenyl-α-naphthylamine, or a combination thereof can be preferably used.

As examples of hindered amine antioxidants, compounds having a 2,2,6,6-tetraalkylpiperidine skeleton (2,2,6,6-tetraalkylpiperidine derivatives) can be cited. As 2,2,6,6-tetraalkylpiperidine derivatives, 2,2,6,6-tetraalkylpiperidine derivatives having a substituent at the 4-position are preferred. In addition, two 2,2,6,6-tetraalkylpiperidine skeletons may be bonded to each other via their respective substituents at the 4-position. In addition, the N-position of the 2,2,6,6-tetraalkylpiperidine skeleton may be unsubstituted or may be substituted with an alkyl group having 1 to 4 carbon atoms. The 2,2,6,6-tetraalkylpiperidine skeleton is preferably a 2,2,6,6-tetramethylpiperidine skeleton.

Examples of the substituent at the 4-position of the 2,2,6,6-tetraalkylpiperidine skeleton include acyloxy (R ¹⁰ COO-), alkoxy (R ¹⁰ O-), alkylamino (R ¹⁰ NH-), acylamino (R ¹⁰ CONH-), etc. ^{R 10} is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably 1 to 24 carbon atoms, and even more preferably 1 to 20 carbon atoms. Examples of the hydrocarbon group include alkyl, alkenyl, cycloalkyl, alkylcycloalkyl, aryl, alkylaryl, arylalkyl, etc.

When two 2,2,6,6-tetraalkylpiperidine skeletons are bonded via the substituent at their respective 4-positions, examples of the substituent include alkylenebis(carbonyloxy) (-OOC-R ¹¹ -COO-), alkylenediamino (-HN-R ¹¹ -NH-), alkylenebis(carbonylamino) (-HNCO-R ¹¹ -CONH-), etc. ^{R 11} is preferably an alkylene group having 1 to 30 carbon atoms, and more preferably an alkylene group.

As a substituent at the 4-position of the 2,2,6,6-tetraalkylpiperidine skeleton, an acyloxy group is preferred. As an example of a compound having an acyloxy group at the 4-position of the 2,2,6,6-tetraalkylpiperidine skeleton, an ester formed by 2,2,6,6-tetramethyl-4-piperidinol and a carboxylic acid can be cited. As an example of the carboxylic acid, a linear or branched aliphatic carboxylic acid having 8 to 20 carbon atoms can be cited.

Examples of the component (D2) (phenolic antioxidant) 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′-butylenebis(3-methyl-6-tert-butylphenol); 4,4′-isopropylidenebis(2,6-di-tert-butylphenol); 2,2′-methylenebis(4-methyl-6-nonylphenol); 2,2′-isobutylenebis(4,6-dimethylphenol); 2,2′-methylenebis(4-methyl-6-cyclohexylphenol); 2 ,6-di-tert-butyl-4-methylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,4-dimethyl-6-tert-butylphenol; 2,6-di-tert-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) propionate; 3-methyl-5-tert-butyl-4-hydroxyphenol fatty acid esters and other hindered phenol compounds and bisphenol compounds. Examples of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionates include octyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; decyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; dodecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; tetradecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 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'-thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the like.

When the lubricating oil composition contains the component (D), the content thereof is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and in one embodiment 0.3% by mass or more, based on the total amount of the composition, as the total amount of the components (D1) and (D2), from the viewpoint of reducing the increase in the acid value of the composition after oxidative degradation. Furthermore, from the viewpoint of further improving the electrical insulation properties of the new oil and the composition after oxidative degradation, the content thereof is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and in one embodiment 2.3% by mass or less. In one embodiment, it may be 0.1 to 3.0% by mass, or 0.2 to 2.5% by mass, or 0.3 to 2.3% by mass.

＜(E) Additives containing phosphorus or sulfur＞

In a preferred embodiment, the lubricating oil composition may further contain one or more phosphorus-containing compounds (hereinafter also referred to as component (E1)), or one or more sulfur-containing compounds containing at least one sulfur atom with a formal oxidation number of +II or less in one molecule (hereinafter also referred to as component (E2)), or a combination thereof (hereinafter also referred to as component (E)).

As the component (E1), a phosphorus-containing compound that functions as an anti-wear agent or an extreme pressure agent in lubricating oil can be used. As the component (E1), one phosphorus-containing compound can be used alone or two or more phosphorus-containing compounds can be used in combination.

Examples of the component (E1) include phosphites, thiophosphites, dithiophosphites, trithiophosphites, phosphates, thiophosphoric acid esters, dithiophosphoric acid esters, trithiophosphoric acid esters, amine salts thereof, and metal salts thereof.

These phosphoric acid-containing esters usually have a hydrocarbon group having 2 to 30 carbon atoms, preferably 3 to 20 carbon atoms. Examples of the hydrocarbon group having 2 to 30 carbon atoms include alkyl, cycloalkyl, alkyl-substituted cycloalkyl, alkenyl, aryl, alkyl-substituted aryl, and aryl-substituted alkyl. These alkyl groups may be linear or branched.

In addition, as examples of ester salts containing phosphoric acid, there can be listed salts in which a part or all of the residual acidic hydrogen is neutralized by allowing a metal base, or a nitrogen-containing compound such as an amine compound containing only ammonia, a hydrocarbon group having 1 to 8 carbon atoms, or a hydroxyl-containing hydrocarbon group in the molecule to act on a partial phosphate ester, a monothiophosphate partial ester, a dithiophosphate partial ester, a trithiophosphate partial ester, a phosphite partial ester, a thiophosphite partial ester, or a dithiophosphite partial ester.

As the component (E1), a phosphite compound represented by the following general formula (8) can be particularly preferably used.

【Chemistry 4】

In the general formula (8), R ¹² and R ¹³ each independently represent a linear hydrocarbon group having 1 to 18 carbon atoms or a group having 4 to 20 carbon atoms represented by the following general formula (9).

【Chemistry 5】

In the general formula (9), R ¹⁴ is a straight-chain hydrocarbon group having 2 to 17 carbon atoms, preferably an ethylene group or a propylene group, and in one embodiment, may be an ethylene group. R ¹⁵ is a straight-chain hydrocarbon group having 2 to 17 carbon atoms, preferably a straight-chain hydrocarbon group having 2 to 16 carbon atoms, and particularly preferably a straight-chain hydrocarbon group having 6 to 10 carbon atoms. ^{X 1} is an oxygen atom or a sulfur atom, preferably a sulfur atom. The number of carbon atoms of the group represented by the general formula (9) is preferably 5 to 20.

In this specification, "phosphorous acid" refers to phosphorus oxo acid H ₃ PO ₃ with an oxidation number of +III. It should be noted that the phosphite compound represented by the general formula (8) generally has tautomerism, and in this specification, any tautomer of the compound represented by the general formula (8) belongs to the component (E1).

In one embodiment, preferred examples of ^R12 and ^R13 include linear alkyl groups having 4 to 18 carbon atoms. Examples of linear alkyl groups include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl.

In one embodiment, preferred examples of R ¹² and R ¹³ include 3-thiapentyl, 3-thiahexyl, 3-thiaheptyl, 3-thiaoctyl, 3-thianonyl, 3-thiadecyl, 3-thiaundecyl, 4-thiahexyl, 3-oxapentyl, 3-oxaheptyl, 3-oxaoctyl, 3-oxanononyl, 3-oxadecyl, 3-oxaundecyl, 3-oxadodecyl, 3-oxatridecyl, 3-oxatetradecyl, 3-oxapentadecyl, 3-oxahexadecyl, 3-oxaheptyl, 3-oxaheptyl, 3-oxanonyl, 3-oxadecyl, 3-oxaundecyl, 3-oxadodecyl, 3-oxatridecyl, 3-oxatetradecyl, 3-oxapentadecyl, 3-oxahexadecyl, 3-oxaheptadecyl, 3-oxaheptadecyl, 3-oxanonadecyl, 4-oxahexyl, 4-oxaheptyl and 4-oxaoctyl.

As component (E2), a sulfur-containing compound that functions as an anti-wear agent or extreme pressure agent in a lubricating oil can be used. Such a sulfur-containing compound contains at least one sulfur atom with a formal oxidation number of +II or less in one molecule. In this specification, the formal oxidation number of the sulfur atom is determined based on the relationship between the electronegativity of the atom bonded to the sulfur atom and the electronegativity of the sulfur atom. That is, in the bond between the sulfur atom and the atom X, if the electronegativity of the element X is greater than the electronegativity of sulfur, it is considered that all the electrons involved in the bond between the two atoms belong to the atom X. Conversely, in the bond between the sulfur atom and the atom X, if the electronegativity of the element X is smaller than the electronegativity of sulfur, it is considered that all the electrons involved in the bond between the two atoms belong to the sulfur atom. The oxidation number of the bond between sulfur atoms does not change. In this specification, the electronegativity of all elements including sulfur is subject to the electronegativity of Allred-Rochow.

Examples of the component (E2) include thiadiazole compounds, sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dialkyl (poly) sulfides, alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, dialkyl thiodipropionate compounds, sulfurized mineral oils, zinc dithiocarbamate compounds, molybdenum dithiocarbamate compounds, sulfolane compounds, etc. As the component (E2), one sulfur-containing compound may be used alone, or two or more sulfur-containing compounds may be used in combination.

Preferred examples of the thiadiazole compound include 1,3,4-thiadiazole compounds represented by the following general formula (10), 1,2,4-thiadiazole compounds represented by the following general formula (11), and 1,2,3-thiadiazole compounds represented by the following general formula (12).

【Chemistry 6】

【Chemistry 7】

【Chemistry 8】

(In general formulae (10) to (12), ^R16 and ^R17 may be the same or different and each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms; f and g may be the same or different and each independently represents an integer of 0 to 8.)

Among the above-mentioned thiadiazole compounds, thiadiazole compounds represented by any one of the above-mentioned general formulas (10) to (12) and having a hydrocarbyl disulfide group are particularly preferably used.

Sulfurized fats and oils are products obtained by the reaction of sulfur or sulfur-containing compounds with fats and oils (lard, whale oil, vegetable oil, fish oil, etc.) The sulfur content in the sulfurized fats and oils is not particularly limited, but is usually 5 to 30% by weight.

As the sulfurized fatty acid, a product obtained by sulfurizing an unsaturated fatty acid by any method can be used, and examples thereof include sulfurized oleic acid.

As the sulfided ester, a product obtained by sulfiding an unsaturated fatty acid ester by any method (for example, a product obtained by reacting an unsaturated fatty acid (oleic acid, linoleic acid or a fatty acid extracted from the above-mentioned animal and plant oils and fats) with various alcohols) can be used. Examples thereof include methyl oleate sulfide and octyl rice bran fatty acid sulfide.

Examples of sulfided olefins include compounds represented by the following general formula (13). The compounds can be obtained by reacting an olefin having 2 to 15 carbon atoms or dimers to tetramers thereof with a sulfiding agent such as sulfur or sulfur chloride. As the olefin, propylene, isobutylene, diisobutylene, etc. can be preferably used.

【Chemistry 9】

^R18 - _Sh - ^R19 (13)

(In the general formula (13), ^R18 represents an alkenyl group having 2 to 15 carbon atoms, ^R19 represents an alkyl group or alkenyl group having 2 to 15 carbon atoms, and h represents an integer of 1 to 8.)

The dihydrocarbyl (poly)sulfide is a compound represented by the following general formula (14): When R ¹⁵ and R ¹⁶ are alkyl groups, it is referred to as an alkyl sulfide.

【Chemistry 10】

^R20 - _Si - ^R21 (14)

(In the general formula (14), ^R20 and ^R21 may be the same or different, and each independently represents an alkyl group having 1 to 20 carbon atoms (which may be linear or branched, or may have a cyclic structure), an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, and i represents an integer of 1 to 8.)

Examples of the alkylthiocarbamoyl compound include compounds represented by the following general formula (15).

【Chemistry 11】

(In the general formula (15), R ²² to R ²⁵ may be the same or different, and each independently represents an alkyl group having 1 to 20 carbon atoms, and k represents an integer of 1 to 8.)

Examples of the alkylthiocarbamate compound include compounds represented by the following general formula (16).

【Chemistry 12】

(In the general formula (16), R ²⁶ to R ²⁹ may be the same or different and each represents an alkyl group having 1 to 20 carbon atoms, and R ³⁰ represents an alkylene group having 1 to 10 carbon atoms.)

Examples of the thioterpene compound include a reaction product of phosphorus pentasulfide and pinene.

Examples of the dialkyl thiodipropionate compound include dilauryl thiodipropionate and distearyl thiodipropionate.

Sulfurized mineral oil is a substance obtained by dissolving elemental sulfur in mineral oil. The mineral oil used in the sulfided mineral oil is not particularly limited, and examples thereof include paraffinic mineral oils, cycloparaffinic mineral oils, etc., which are refined by applying an appropriate combination of known refining treatments to the lubricating oil fractions obtained by applying atmospheric distillation and vacuum distillation to crude oil. In addition, as elemental sulfur, any form such as block, powder, molten liquid, etc. can be used. The sulfur content in the sulfided mineral oil is not particularly limited, and is usually 0.05 to 1.0% by weight based on the total amount of the sulfided mineral oil.

As the zinc dithiocarbamate compound, a compound represented by the following general formula (17) can be used, and as examples of the molybdenum dithiocarbamate compound, a compound represented by the following general formula (18) can be mentioned.

【Chemistry 13】

(In the general formula (17), R ³¹ to R ³⁴ may be the same or different, and each independently represents a hydrocarbon group having 1 or more carbon atoms.)

【Chemistry 14】

(In the general formula (18), R ³⁵ to R ³⁸ may be the same or different, and each independently represents a hydrocarbon group having 1 or more carbon atoms, and Y ¹ to Y ⁴ each independently represents an oxygen atom or a sulfur atom.)

It should be noted that although the dithiocarbamate molybdenum compound of the general formula (18) is a binuclear complex having two molybdenum atoms in one molecule, a mononuclear molybdenum complex having one molybdenum atom in one molecule or a polynuclear molybdenum complex having three or more molybdenum atoms in one molecule may also be used as the dithiocarbamate molybdenum compound.

As the sulfolane compound, for example, a compound represented by the following general formula (19) can be used.

【Chemistry 15】

(In the general formula (19), l represents an integer of 1 or 2, m represents an integer of 0 or 1, and when m=1, ^R39 represents a hydrocarbon group having 1 or more carbon atoms.)

The lubricating oil composition may contain component (E) or may not contain it. From the viewpoint of further improving the electrical insulation of the new oil and the composition after oxidation and deterioration, the content of component (E) in the lubricating oil composition is preferably 0 to 1000 mass ppm, more preferably 0 to 900 mass ppm, and further preferably 0 to 800 mass ppm, based on the total content of the phosphorus component and the sulfur component, and from the viewpoint of improving the wear resistance, it is preferably 300 mass ppm or more, more preferably 400 mass ppm or more, and further preferably 500 mass ppm or more, and in one embodiment, it may be 300 to 1000 mass ppm, or 400 to 900 mass ppm, or 500 to 800 mass ppm. It should be noted that in this specification, any phosphorus-containing additive should be included in the content of component (E1), and additives containing only sulfur with a formal oxidation number of +II or less but no phosphorus are included in the content of component (E2). In addition, when the component (E1) contains both phosphorus and sulfur with a formal oxidation number of +II or less, the component (E1) is included in both the content calculated as the phosphorus component and the content calculated as the sulfur component in the component (E). It should be noted that the component (E) is a compound containing a phosphorus atom or a sulfur atom with a formal oxidation number of +II or less, but when the component (E) further contains a sulfur atom with a formal oxidation number of +III or more, the sulfur atom with any formal oxidation number in the component (E) is also included in the content calculated as the sulfur component in the component (E).

<(F) Poly(meth)acrylate>

In one embodiment, the lubricating oil composition of the present invention may further contain one or more poly(meth)acrylic acid alkyl esters having a weight average molecular weight of greater than 25,000 (hereinafter also referred to as "component (F)"). As component (F), one poly(meth)acrylic acid alkyl ester may be used alone, or two or more poly(meth)acrylic acid alkyl esters may be used in combination. It should be noted that "(meth)acrylic acid" in this specification means "acrylic acid and/or methacrylic acid".

As component (F), a poly(meth)acrylic acid alkyl ester used as a viscosity index improver or pour point depressant in lubricating oil can be used without particular limitation. Any of non-dispersible poly(meth)acrylate and dispersed poly(meth)acrylate can be used as component (F), or a combination thereof. Based on the viewpoint of improving sintering resistance, non-dispersible poly(meth)acrylate is preferably used. In this specification, "dispersible poly(meth)acrylate" refers to a poly(meth)acrylate compound having a functional group containing a nitrogen atom, and "non-dispersible poly(meth)acrylate" refers to a poly(meth)acrylate compound not having a functional group containing a nitrogen atom.

From the viewpoint of improving fatigue resistance and further improving the electrical insulation of the new oil, the weight average molecular weight of the component (F) is preferably greater than 25,000, more preferably greater than 27,000. From the viewpoint of improving seizure resistance, it is preferably 100,000 or less, more preferably 80,000 or less. In one embodiment, it may be greater than 25,000 and 100,000 or less, or 27,000 to 80,000.

The lubricating oil composition may or may not contain the component (F). From the viewpoint of further improving fuel efficiency, the content of the component (G) in the lubricating oil composition is preferably 0 to 5.0% by mass, more preferably 0 to 4.0% by mass, based on the total amount of the composition. From the viewpoint of further improving the low-temperature fluidity of the new oil, the content is preferably 0.01% by mass or more, more preferably 0.015% by mass or more. In one embodiment, the content may be 0.01 to 5.0% by mass, or 0.015 to 4.0% by mass.

＜Other additives＞

In one embodiment, the lubricating oil composition may further contain a friction modifier other than the components (B) and (E), a viscosity index improver other than the component (F), a pour point depressant other than the component (F), a corrosion inhibitor and a rust inhibitor other than the component (E), and one or more additives selected from the group consisting of a metal deactivator, a defoamer, an anti-emulsifier and a colorant other than the component (E).

As the friction modifier other than the component (B) and the component (E), for example, one or more friction modifiers selected from the group consisting of an oil-soluble organic molybdenum compound other than the component (E) and an ashless friction modifier other than the component (B) can be used. The lubricating oil composition may not contain a friction modifier, but from the viewpoint of further improving the electrical insulation of the new oil and the composition after oxidation and deterioration, the content of the friction modifier in the lubricating oil composition is preferably 0 to 2 mass %, more preferably 0 to 1 mass %, based on the total amount of the composition. The lower limit of the content is not particularly limited, and in one embodiment, it may be 0.005 mass % or more.

Examples of oil-soluble organic molybdenum compounds other than component (E) include organic molybdenum compounds that do not contain sulfur as a constituent element. Examples of organic molybdenum compounds that do not contain sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, organic acid molybdenum salts, alcohol molybdenum salts, etc. It should be noted that 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.

The lubricating oil composition may contain metal-containing additives (e.g., organic molybdenum compounds or zinc dialkyl dithiophosphates) other than the metal detergent, or may not contain them. From the viewpoint of further improving the electrical insulation of new oil and the composition after oxidative degradation, the total content of metal elements in the lubricating oil composition is preferably less than 100 mass ppm in terms of metal amount based on the total amount of the composition. In one embodiment, the total content of metal-containing additives other than the component (C) in the lubricating oil composition is preferably 0 to 50 mass ppm, more preferably 0 to 30 mass ppm, and even more preferably 0 to 10 mass ppm in terms of metal amount based on the total amount of the composition.

As the ashless friction modifier other than the component (B), known oiliness-based friction modifiers can be used without limitation. Examples of ashless friction modifiers include compounds having 6 to 50 carbon atoms and containing one or more heteroelements selected from oxygen atoms, nitrogen atoms, and sulfur atoms in the molecule. More specifically, ashless friction modifiers such as aliphatic amine compounds, aliphatic imide compounds, fatty acid esters, fatty acid amides, fatty acid hydrazides, fatty acid metal salts, aliphatic alcohols, aliphatic ethers, and aliphatic urea compounds having at least one alkyl or alkenyl group having 6 to 30 carbon atoms, preferably a linear or branched alkyl or alkenyl group having 6 to 30 carbon atoms in the molecule can be preferably used.

As the viscosity index improver other than the component (F), known viscosity index improvers used in lubricating oils can be used without limitation. Examples thereof include ethylene-α-olefin copolymers and hydrogenates thereof, copolymers of α-olefins and ester monomers having polymerizable unsaturated bonds, polyisobutylene and hydrogenates thereof, hydrogenates of styrene-diene copolymers, styrene-maleic anhydride ester copolymers, and polyalkylstyrene. Among these, ethylene-α-olefin copolymers or hydrogenates thereof, or combinations thereof, can be preferably used. The viscosity index improver can be a dispersed type or a non-dispersed type. In one embodiment, the weight average molecular weight of the viscosity index improver can be, for example, 3000 to 100,000. The lubricating oil composition may contain a viscosity index improver or may not contain one. From the viewpoint of further improving the electrical insulation of the composition after oxidative degradation, the total content of the viscosity index improver in the lubricating oil composition is preferably 0 to 5.0% by mass, more preferably 0 to 4.0% by mass, based on the total amount of the composition. The lower limit of the total content is not particularly limited, and in one embodiment, it can be 0.1% by mass or more.

As the pour point depressant other than the component (F), for example, a known pour point depressant such as ethylene-vinyl acetate copolymer can be used depending on the properties of the lubricating base oil used. The lubricating oil composition may contain a pour point depressant other than the component (F), or may not contain it. From the viewpoint of further improving the electrical insulation of the composition after oxidative degradation, the content of the pour point depressant other than the component (F) in the lubricating oil composition is preferably 0 to 1% by mass, more preferably 0 to 0.8% by mass, based on the total amount of the composition. The lower limit of the content is not particularly limited, and in one embodiment, it may be 0.015% by mass or more.

The lubricating oil composition may or may not contain a polymer component other than the component (F) (e.g., a viscosity index improver or a pour point depressant). From the viewpoint of further improving the electrical insulation properties of the composition after oxidative degradation, the content of the polymer component having a weight average molecular weight of 25,000 or less in the lubricating oil composition is preferably 0 mass % or more and less than 0.1 mass %, more preferably 0 to 0.05 mass %, and particularly preferably 0 to 0.01 mass %.

As the anticorrosive agent other than the component (E), for example, known anticorrosive agents such as benzotriazole, methylbenzotriazole and imidazole compounds can be used. The lubricating oil composition may contain or not contain an anticorrosive agent other than the component (E). From the viewpoint of further improving the electrical insulation of the new oil and the composition after oxidation and deterioration, the content of the anticorrosive agent other than the component (E) in the lubricating oil composition is preferably 0 to 1% by mass, more preferably 0 to 0.5% by mass, based on the total amount of the composition. The lower limit of the content is not particularly limited, and in one embodiment, it may be 0.01% by mass or more.

As the rust inhibitor, for example, known rust inhibitors such as petroleum sulfonates, alkylbenzene sulfonates, dinonylnaphthalene sulfonates, alkenyl succinates, and polyol esters can be used. The lubricating oil composition may contain a rust inhibitor or may not contain one. From the viewpoint of further improving the electrical insulation of new oil and the composition after oxidation and deterioration, the content of the rust inhibitor in the lubricating oil composition is preferably 0 to 1% by mass, more preferably 0 to 0.5% by mass or less based on the total amount of the composition. The lower limit of the content is not particularly limited, and in one embodiment, it may be 0.01% by mass or more.

As metal deactivators other than component (E), for example, known metal deactivators such as imidazoline, pyrimidine derivatives, mercaptobenzothiazole, 2-(alkyldisulfide)benzimidazole, and β-(o-carboxybenzylthio)propionitrile can be used. The lubricating oil composition may contain or not contain metal deactivators other than component (E). From the viewpoint of further improving the electrical insulation of the new oil and the composition after oxidative degradation, the content of metal deactivators other than component (E) in the lubricating oil composition is preferably 0 to 1% by mass, more preferably 0 to 0.5% by mass, based on the total amount of the composition. The lower limit of the content is not particularly limited, and in one embodiment, it may be 0.01% by mass or more.

As the defoaming agent, for example, known defoaming agents such as silicone, fluorosilicone, and fluoroalkyl ether can be used. The lubricating oil composition may contain a defoaming agent or not. From the viewpoint of further improving the electrical insulation of new oil and the composition after oxidation and deterioration, the content of the defoaming agent in the lubricating oil composition is preferably 0 to 0.5 mass%, more preferably 0 to 0.1 mass%. The lower limit of the content is not particularly limited, and in one embodiment, it can be 0.0001 mass% or more.

As the demulsifier, for example, a known demulsifier such as a polyalkylene glycol-based nonionic surfactant (e.g., polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylnaphthyl ether, etc.) can be used. The lubricating oil composition may contain a demulsifier or not. From the viewpoint of further improving the electrical insulation of the new oil and the composition after oxidation deterioration, the content of the demulsifier in the lubricating oil composition is preferably 5% by mass or less, more preferably 3% by mass or less, based on the total amount of the composition. The lower limit of the content is not particularly limited, and in one embodiment, it may be 1% by mass or more.

As the colorant, for example, a known colorant such as an azo compound can be used.

<Lubricating oil composition>

The kinematic viscosity of the lubricating oil composition at 100°C is preferably 1.8 mm ² /s or more, preferably 2.0 mm 2 /s or more, more preferably 2.2 mm ² /s or more, and in one embodiment, 2.3 mm ² /s or more, from the viewpoint of further improving the electrical insulation of new oil and the composition after oxidative degradation and from the viewpoint of sufficiently forming an oil film at the lubrication site to improve the wear resistance. From the viewpoint of improving fuel efficiency, it is preferably 4.0 ^{mm 2 /} s or less, preferably 3.8 mm ² /s or less, and in one embodiment, it may be 1.8 to 4.0 mm ² /s, or 2.0 to 4.0 mm ² /s, or 2.2 to 4.0 mm ² /s, or 2.3 to 3.8 mm ² /s.

From the viewpoint of further improving the electrical insulation properties of new oil and the composition after oxidative degradation and the wear resistance, the kinematic viscosity of the lubricating oil composition at 40°C is preferably 6.8 mm ² /s or more, more preferably 7.2 mm ² /s or more, and in one embodiment, 8.0 mm ² /s or more. From the viewpoint of further improving the fuel economy, the kinematic viscosity is preferably 14.5 mm ² /s or less, more preferably 13.7 mm ² /s or less, and in one embodiment, 13.0 mm ² /s or less. In one embodiment, it may be 6.8 to 14.5 mm ² /s, 7.2 to 13.7 mm ² /s, or 8.0 to 13.0 mm ² /s.

From the perspective of improving energy efficiency, the lower the kinematic viscosity of the lubricating oil composition, the better. However, generally, if an additive is added to the base oil ((O) component), the overall kinematic viscosity of the lubricating oil composition increases. This means that the critical point for improving energy efficiency by reducing the viscosity of the lubricating oil is determined based on the kinematic viscosity of the total base oil ((O) component). Therefore, from the perspective of improving energy efficiency, the lower the kinematic viscosity of the total base oil, the better. On the other hand, from the perspective of wear resistance, oxidation stability, and new oil and improving the electrical insulation of the composition after oxidation and deterioration, the kinematic viscosity of the total base oil is preferably above a certain level. Under the constraint of maintaining the kinematic viscosity of the total base oil above a specified level, it is the thickening effect of the additive that hinders the low viscosity of the lubricating oil. From the viewpoint of further improving energy saving performance, the difference _{( KV40Comp} ^- _KV40BO ⁾ between the kinematic viscosity at ⁴⁰ °C of the lubricating oil composition and the kinematic viscosity at 40°C of the total base oil ((O) component), ^i.e. _, the viscosity increasing effect of the additive, is preferably 2.5 ^mm2 /s or less, and in one embodiment, 2.4 ^mm2 /s or less. From the viewpoint of further improving the durability against oxidative degradation, it is preferably 1.0 ^mm2 /s or more, more preferably 1.5 ^mm2 /s or more, and in one embodiment, 1.8 ^mm2 /s or more. In one embodiment, it may be 1.0 to 2.5 ^mm2 /s, 1.5 to 2.5 ^mm2 /s, or 1.8 to 2.4 ^mm2 /s.

From the viewpoint of further improving fuel efficiency and wear resistance, the viscosity index of the lubricating oil composition is preferably 100 or more, more preferably 110 or more, and in one embodiment, may be 115 or more, or 120 or more.

In one embodiment, the volume resistivity of the new oil of the lubricating oil composition at 80°C is preferably 0.21×10 ¹⁰ Ω·cm or more. The upper limit of the volume resistivity of the new oil at 80°C is not particularly limited, and in one embodiment, the volume resistivity may be 0.21×10 ¹⁰ to 0.60×10 ¹⁰ Ω·cm, or 0.21×10 ¹⁰ to 0.45×10 ¹⁰ Ω·cm. In this specification, the volume resistivity of the new oil is measured at an oil temperature of 80°C based on the volume resistivity test specified in JIS C2101.

In one embodiment, the volume resistivity of the oxidatively degraded oil of the lubricating oil composition at 80°C is preferably 0.10×10 ¹⁰ Ω·cm or more. The upper limit of the volume resistivity of the oxidatively degraded oil at 80°C is not particularly limited, and in one embodiment, the volume resistivity may be 0.10×10 ¹⁰ to 0.40×10 ¹⁰ Ω·cm, or 0.10×10 ¹⁰ to 0.25×10 ¹⁰ Ω·cm. In the present specification, the volume resistivity of the oxidatively degraded oil is obtained by oxidatively treating new oil at 165°C for 150 hours according to the ISOT method (Indiana Stirring Oxidation Test) specified in JIS K2514-1, and measuring the oxidatively degraded oil at an oil temperature of 80°C according to the volume resistivity test specified in JIS C2101.

In one embodiment, the content of any of the metal detergents (e.g., metal salicylic acid detergents, metal sulfonic acid detergents, metal phenolate detergents, etc. such as component (C)), phosphite diester compounds having no O/N-based active hydrogen-containing groups on the alcohol residue (e.g., phosphite compounds represented by general formula (8) (component (E1)), etc.), the first succinimide compound (component (A)), the second succinimide compound (component (B)), the amine antioxidant or the phenolic antioxidant (component (D)), and the poly (meth)acrylate (e.g., component (F)), having a non-phenolic OH group (the OH group may be a part of other functional groups (e.g., carboxyl group, phosphate group)) or a salt thereof, >NH group, or -NH The total content of compounds containing ₂ groups (hereinafter referred to as "O/N-based active hydrogen groups") (hereinafter referred to as "O/N-based active hydrogen compounds") is preferably 0 to 500 mass ppm, in terms of the total amount of oxygen and nitrogen elements based on the total amount of the composition, from the viewpoint of further improving the electrical insulation properties of the new oil and the composition after oxidative degradation, and is 0 to 300 mass ppm in one embodiment, and can be 0 to 150 mass ppm in another embodiment. Examples of such O/N active hydrogen compounds include phosphoric acid and partial esters thereof and salts thereof; phosphorous acid and partial esters thereof and salts thereof (however, phosphorous acid diesters which do not have the above-mentioned O/N active hydrogen-containing groups on the alcohol residue do not belong to the O/N active hydrogen compounds); nitrogen-containing oily agent friction modifiers having NH bonds (for example, aliphatic primary amines, aliphatic secondary amines, fatty acid primary amides, fatty acid secondary amides, aliphatic ureas having N-H bonds, fatty acid hydrazides, etc.); nitrogen-containing oily agent friction modifiers having hydroxyl groups (for example, amides formed between fatty acids and primary or secondary alkanolamines, amides formed between aliphatic primary or secondary amines and aliphatic hydroxy acids, etc.); nitrogen-containing oily agent friction modifiers having carboxyl groups (which can form salts) (for example, N-acylated amino acids, etc.); oily agent friction modifiers having hydroxyl groups (for example, glycerol monooleate, etc.); and oily agent friction modifiers having carboxyl groups (which can form salts) (for example, fatty acids and fatty acid metal salts, etc.). When an O/N-based active hydrogen compound contains both oxygen and nitrogen, regardless of whether each oxygen atom of the compound is bonded to a hydrogen atom and whether each nitrogen atom of the compound is bonded to a hydrogen atom, both the amount of oxygen and the amount of nitrogen from the compound are included in the total content of the above-mentioned O/N-based active hydrogen compound (the total amount of oxygen and nitrogen).

(use)

The lubricating oil composition of the present invention has low viscosity and electrical insulation required for lubricating electric engines, thereby alleviating the problems caused by oxidation deterioration in the lubrication of automatic transmissions and electric engines. In addition to being preferably used for lubrication of automatic transmissions as a lubricating oil with improved fuel efficiency, it can also be preferably used for lubrication and cooling of electric engines as a lubricating oil with improved energy efficiency. In addition, the lubricating oil composition of the present invention can also be used to lubricate both automatic transmissions and electric engines. Such a lubricating method, for example, can include supplying the lubricating oil composition of the present invention to an automatic transmission of a car having an automatic transmission and an electric engine, and supplying the lubricating oil composition to the electric engine of the car.

[Example]

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

<Examples 1 to 20 and Comparative Examples 1 to 8>

As shown in Tables 1 to 6, the lubricating oil compositions of the present invention (Examples 1 to 20) and comparative lubricating oil compositions (Comparative Examples 1 to 8) were prepared, respectively. In the table, "mass %" in the "base oil composition" item means mass % based on the total amount of the base oil (100 mass %), and "mass %" in other items means mass % based on the total amount of the lubricating oil composition (100 mass %). In addition, "mass ppm" means mass ppm based on the total amount of the lubricating oil composition, and the expression of "mass ppm/X" of element X means mass ppm based on the total amount of the composition as the amount of element X. The details of each component are as follows.

((O) Lubricant base oil)

O-1: API Group III base oil (hydrogenated cracked mineral oil base oil), kinematic viscosity (40°C): 7.0 mm ² /s, kinematic viscosity (100°C): 2.2 mm ² /s, viscosity index: 121, saturation content: 99.6, sulfur content: less than 1 mass ppm, % _CP : 77.4, % _CN : 22.0, % _CA : 0.6

O-2: API Group III base oil (hydrogenated cracked mineral oil base oil), kinematic viscosity (40°C): 19.2 mm ² /s, kinematic viscosity (100°C): 4.2 mm ² /s, viscosity index: 124, saturated content: 99.7, sulfur content: less than 1 mass ppm, % _CP : 79.4, % _CN : 20.6, % _CA : 0.0

O-3: API Group III base oil (hydrogenated cracked mineral oil base oil), kinematic viscosity (40°C): 18.2 mm ² /s, kinematic viscosity (100°C): 4.2 mm ² /s, viscosity index: 135, saturated content: 99.8, sulfur content: less than 1 mass ppm, % _CP : 86.6, % _CN : 13.4, % _CA : 0.0

O-4: API Group III base oil (wax isomerized mineral oil-based base oil), kinematic viscosity (40°C): 9.2 mm ² /s, kinematic viscosity (100°C): 2.6 mm ² /s, viscosity index: 126, saturated content: 99.8, sulfur content: less than 1 mass ppm, % _CP : 91.8, % _CN : 8.2, % _CA : 0.0

O-5: API Group IV base oil, kinematic viscosity (40°C): 18.4 mm ² /s, kinematic viscosity (100°C): 4.1 mm ² /s, viscosity index: 124

O-6: API Group V base oil (2-ethylhexyl oleate), kinematic viscosity (40°C): 8.2 mm ² /s, kinematic viscosity (100°C): 2.7 mm ² /s, viscosity index: 186

((A) First Succinimide Compound)

A-1: condensation reaction product of polyisobutenyl succinic anhydride and polyamine (unmodified polyisobutenyl succinimide dispersant), weight average molecular weight: 5200, N: 1.3 mass %, number average molecular weight of polyisobutenyl group: 1600

A-2: boric acid-modified product of the condensation reaction product of polyisobutenyl succinic anhydride and polyamine (boric acid-modified polyisobutenyl succinimide dispersant), weight average molecular weight: 9100, N: 0.73 mass%, B: 0.19 mass%, number average molecular weight of polyisobutenyl group: 2500

((B) Second succinimide compound)

B-1: condensation reaction product of octadecenylsuccinic anhydride and polyamine, N: 5.3 mass %

((C) Metal Cleaner)

C-1: calcium carbonate overbased calcium sulfonate, base value 300 mgKOH/g, Ca: 12.0 mass%

((D) Antioxidant)

D-1: Amine antioxidant (alkylated diphenylamine)

D-2: Phenolic antioxidant (3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)

((E) Phosphorus/Sulfur Additives)

E-1: bis(3-thiaundecyl)phosphite, P: 7.3 mass%

E-2: a thiadiazole compound represented by the general formula (10) to (12) having an alkyl group bonded to the thiadiazole ring via a disulfide bond (f, g = 2), S: 36 mass%

【Table 1】

【Table 2】

【Table 3】

【Table 4】

【Table 5】

【Table 6】

(Viscosity increase due to additives)

For each lubricating oil composition, the viscosity increase due to the additive was evaluated by calculating the increase (KV _{40 Comp - KV 40 BO ) of the composition's kinematic viscosity at 40°C (KV 40 Comp ) relative to the kinematic viscosity at 40°C (KV 40} ^BO ₎ ^of _the ^total base oil ((O) ^component ). The results are shown in Tables 1 to 6. The smaller the value, the smaller the reduction in energy saving due to the viscosity increasing effect of the additive. The increase in 40°C kinematic viscosity due to the additive is preferably 2.5 mm ² /s or less.

(ISOT oxidation test)

For each lubricating oil composition, based on the ISOT (Indiana Stirring Oxidation Test) method in JIS K2514-1, the new oil was subjected to an oxidation treatment at an oil temperature of 165°C for 150 hours to obtain an oxidatively deteriorated oil. For the new oil and the oxidatively deteriorated oil, the acid value was measured by the potentiometric titration method based on JIS K2501-2003, and the increase in the acid value after oxidative deterioration was evaluated. The results are shown in Tables 1 to 6. The smaller the increase in the acid value in this test, the better the durability against oxidative deterioration. The increase in the acid value in this test is preferably 1.5 mgKOH/g or less.

(Volume resistivity)

For each lubricating oil composition, the volume resistivity of the new oil and the volume resistivity of the oxidatively deteriorated oil measured by the above-mentioned ISOT oxidation test were measured. For each new oil and oxidatively deteriorated oil, the volume resistivity was measured based on the volume resistivity test specified in JIS C2101 and was performed at an oil temperature of 80°C. The results are shown in Tables 1 to 6. The higher the volume resistivity in this test, the better the electrical insulation. The volume resistivity of the new oil at 80°C in this test is preferably 0.21×10 ¹⁰ Ω·cm or more. In addition, the volume resistivity of the oxidatively deteriorated oil at 80°C in this test is preferably 0.10×10 ¹⁰ Ω·cm or more.

(Evaluation results)

The lubricating oil compositions of Examples 1 to 20 had low viscosity due to a small increase in viscosity caused by the additives, and showed good results in terms of the increase in acid value of the oxidatively degraded oil, the electrical insulation of the new oil, and the electrical insulation of the composition after oxidative deterioration.

In the lubricating oil composition of Comparative Example 1 in which the content (mass ppm) of the component (A) as nitrogen was too small, the acid value of the oxidatively degraded oil increased and the electrical insulation properties of the composition after oxidative degradation were poor.

The lubricating oil composition of Comparative Example 2 in which the content (mass %) of the component (A) based on the total amount of compounds was too large had poor electrical insulation properties after oxidative degradation.

The lubricating oil composition of Comparative Example 3, in which the product of the weight average molecular weight of the component (A) and the content (mass %) of the component (A) based on the total compounds was too large, had a large increase in viscosity due to the additive and was inferior in energy saving properties.

The lubricating oil composition of Comparative Example 4, in which the product of the weight average molecular weight of component (A) and the content (mass %) of component (A) based on the total compounds is too large and the content (mass %) of component (A) based on the total compounds is also too large, has a large increase in viscosity due to the additives, poor energy saving properties, and poor electrical insulation properties of the new oil.

The lubricating oil composition of Comparative Example 5 which does not contain the component (B) has a poor increase in the acid value of the oxidatively deteriorated oil.

The lubricating oil composition of Comparative Example 6 in which the content of the component (B) was too large had poor electrical insulation properties after oxidation degradation.

The lubricating oil composition of Comparative Example 7, which does not contain the component (B) but instead increases the content of the component (C), i.e., the metallic detergent, to reduce the increase in the acid value of the oxidatively degraded oil, has poor electrical insulation properties in both the new oil and the oxidatively degraded oil.

The lubricating oil composition of Comparative Example 8, in which the content of component (A) is increased to reduce the acid value of the oxidatively deteriorated oil while the content of component (C) is reduced in the composition of Comparative Example 7, has poor electrical insulation properties as new oil, a large increase in viscosity due to the additives, and poor energy saving properties.

Claims (10)

1. A lubricating oil composition comprising

(O) a kinematic viscosity at 40 ℃ of 6.0 to 12.0mm containing 1 or more mineral base oils or 1 or more synthetic base oils or a combination thereof ² A lubricating base oil of the order of per second,

80 mass ppm or more based on the total amount of the composition and 2.7 mass% or less based on the compound of (A) a condensation reaction product of polyisobutenyl succinic acid having polyisobutenyl groups with a number average molecular weight of 800 or more or an anhydride thereof with a polyamine or a modified product thereof, or a combination thereof,

and 50 to 1300 mass ppm based on the total amount of the composition of (B) a condensation reaction product of an alkyl or alkenyl succinic acid having an alkyl or alkenyl group having 8 to 30 carbon atoms or an anhydride thereof and a polyamine or a modified product thereof, or a combination thereof,

the product of the weight average molecular weight of the component (A) expressed in Da and the content of the component (A) expressed in mass% is 16,000 or less.

2. The lubricating oil composition according to claim 1, wherein the composition contains 10 mass ppm or more and less than 100 mass ppm of (C) 1 or more calcium carbonate overbased calcium sulfonate detergent or 1 or more calcium carbonate overbased calcium salicylate detergent, or a combination thereof, based on the total amount of the composition.

3. The lubricating oil composition according to claim 1 or 2, wherein (D) 1 or more amine antioxidants and 1 or more phenol antioxidants are contained in an amount of 0.1 to 3.0 mass% in total, based on the total amount of the composition.

4. The lubricating oil composition according to any one of claims 1 to 3, wherein (E) 1 or more phosphorus-containing compounds or 1 or more sulfur-containing compounds having at least 1 sulfur atom in the form of an oxidation number of +ii or less or a combination thereof are contained or not contained in an amount of 1000 mass ppm or less based on the total content of the phosphorus component and the sulfur component.

5. The lubricating oil composition according to any one of claims 1 to 4, wherein the content A in terms of nitrogen component based on the total amount of the composition of component (A) and the content B in terms of nitrogen component based on the total amount of the composition of component (B) satisfy the relationship represented by the following formula (1), the content A, B being in mass ppm,

digital type (1)

B≥max(50,f(A))

6. The lubricating oil composition according to any one of claims 1 to 5, wherein 5.0 mass% or less of 1 or more of the (F) polyalkyl (meth) acrylate having a weight average molecular weight of more than 25,000 is contained or not contained based on the total amount of the composition.

7. The lubricating oil composition according to any one of claims 1 to 6, wherein less than 0.1 mass% of 1 or more polymers having a weight average molecular weight of 25,000 or less is contained or not contained, based on the total amount of the composition.

8. The lubricating oil composition according to any one of claims 1 to 7, which is used for lubrication of an automatic transmission.

9. The lubricating oil composition according to any one of claims 1 to 8 for lubrication of an electric engine.

10. An automatic transmission and a lubrication method of an electric engine, comprising supplying the lubricating oil composition according to any one of claims 1 to 9 to the automatic transmission of an automobile having an automatic transmission and an electric engine, and

the lubricating oil composition is supplied to an electric engine of the automobile.