CN116323879A

CN116323879A - Lubricating oil composition

Info

Publication number: CN116323879A
Application number: CN202180067385.1A
Authority: CN
Inventors: 松冈真夕子; 增田耕平; 菖蒲纪子
Original assignee: Eneos Corp
Current assignee: Eneos Corp
Priority date: 2020-10-09
Filing date: 2021-09-24
Publication date: 2023-06-23
Also published as: JP7563935B2; EP4227389A1; JP2022063013A; EP4227389A4; US20230332064A1; WO2022075088A1

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 lubrication of an automatic transmission and/or an electric engine.

Background

One of the energy saving means in gear devices such as a transmission and a final reduction gear is to reduce the viscosity of lubricating oil. For example, a transmission, a final reduction gear, and the like have a gear bearing mechanism, and by reducing the viscosity of the lubricating oil used therein, stirring resistance and drag torque due to viscosity resistance of the lubricating oil can be reduced, and as a result, power transmission efficiency can be improved, and as a result, fuel saving performance can be improved.

Prior art literature

Patent literature

Japanese patent application laid-open No. 2009-249496 (patent document 1)

Japanese patent application laid-open No. 2014-15964

Japanese patent application laid-open No. 2016-003258 (patent document 3)

Japanese patent application laid-open No. 2016-020454 (patent document 4)

[ patent document 5 ] International publication No. 2020/095968

[ patent document 6 ] International publication No. 2020/095969

[ patent document 7 ] International publication No. 2020/095970

International publication No. 2020/171188 (patent document 8)

Disclosure of Invention

Problems to be solved by the invention

In recent years, electric vehicles using an electric engine as a driving power source and hybrid vehicles using an electric engine and an internal combustion engine as driving power sources have been attracting attention from the viewpoints of energy efficiency and environmental compatibility. The electric motor generates heat during operation, and includes a heat-labile member such as a coil or a magnet. Therefore, in these automobiles using an electric engine as a driving power source, a unit for cooling the electric engine is provided. As means for cooling the electric engine, air cooling, water cooling, and oil cooling are known. Among these, the oil cooling method is to circulate oil inside an electric engine, and thereby to bring a heat generating portion (for example, a coil, an iron core, a magnet, or the like) in the electric engine into direct contact with a cooling medium (oil), thereby achieving a high cooling effect. In an oil-cooled electric engine, lubrication and cooling of the electric engine can be performed simultaneously by circulating oil (lubricating oil) in the electric engine. The lubricating oil of an electric engine (electric engine oil) is required to have electrical insulation.

Electric engines and transmissions are typically lubricated with different lubricating oils. If the electric engine and the transmission (gear mechanism) can be lubricated by the same lubricating oil, simplification of the lubricating oil circulation mechanism will become possible. However, conventional transmission oil is insufficient in electrical insulation when used for lubrication of an electric engine. Further, conventional electric engine oils are insufficient in durability against oxidative deterioration when used for transmission (gear mechanism) lubrication.

For lubricating oils such as transmission oil and motor oil which are exposed to a high temperature of a certain level or higher, oxidative deterioration is an element determining the life of the lubricating oil. The high-polarity component generated by the oxidative deterioration of the lubricating oil is not only easily precipitated as an insoluble component, but also reduces the electrical insulation of the lubricating oil. In addition, as oxidation deterioration proceeds, an increase in acid value also causes corrosion of the metal parts.

The detergent dispersant is an important component for alleviating these problems caused by oxidative deterioration of the lubricating oil and improving the long-acting property of the lubricating oil. The detergent dispersant is a concept including an ashless dispersant and a metal-based detergent. The metal-based detergent is a metal salt of an organic acid capable of forming micelles in oil (for example, an alkaline earth metal salicylate, an alkaline earth metal sulfonate, an alkaline earth metal phenate, or the like), or a mixture of the metal salt and a metal base (for example, an oxide, a hydroxide, or the like). Ashless dispersants typically have a polar group (e.g., amine group, etc.) in one molecule that interacts with a highly polar component, and a long chain alkyl or alkenyl group (e.g., polyisobutenyl group, etc.) that has sufficient oiliness to disperse the highly polar component in an oil. Examples of specific compounds used as the ashless dispersant include condensation reaction products of alkyl or alkenyl succinic acids or anhydrides thereof and polyamines, and Mannich reaction products of alkyl or alkenyl phenols and formaldehyde and polyamines. Since the ashless dispersant does not form micelles in the oil, in order to secure the oil property necessary for the function as the ashless dispersant, an alkyl group or alkenyl group having a longer chain than the oil group of the organic acid constituting the metal-based detergent is required. As such an alkyl group or alkenyl group, for example, an alkyl group or alkenyl group (polyisobutenyl group) derived from a polyolefin obtained by polymerization of an olefin such as isobutylene is preferably used. Ashless dispersants therefore typically have a molecular weight greater than that of metal based detergents.

If the content of the metal-based detergent in the lubricating oil is increased, the electrical insulation properties of the new oil tend to be significantly lowered. Therefore, from the viewpoint of ensuring electrical insulation necessary for lubrication of the electric engine, the content of the metal-based detergent in the lubricating oil is preferably small. In order to alleviate the problems caused by oxidative deterioration of the lubricating oil and to improve the long-acting property of the lubricating oil, the content of the ashless dispersant needs to be increased in the lubricating oil in which the metal-based detergent is reduced or no metal-based detergent is contained. However, although the ashless dispersant does not lower the electrical insulation property of the new oil like the metal-based detergent, the viscosity of the lubricating oil is easily increased as compared with the metal-based detergent. Therefore, from the viewpoint of improving the energy saving property of the lubricating oil, the content of the ashless dispersant is preferably small.

The present invention addresses the problem of providing a low-viscosity lubricating oil composition having improved energy saving properties, which is capable of reducing problems caused by oxidation and deterioration in lubrication of an automatic transmission and in lubrication of an electric engine, while having electrical insulation properties required for lubrication of the electric engine, and improving long-term durability.

Technical means for solving the problems

The present invention includes the following embodiments [1] to [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 (unit: da) of the component (A) and the content (unit: mass%) of the component (A) in terms of compounds is 16,000 or less.

[2] The lubricating oil composition of [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 [1] or [2], wherein the total amount of the (D) 1 or more amine antioxidants and 1 or more phenol antioxidants is 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], wherein (E) 1 or more phosphorus-containing compounds or 1 or more sulfur-containing compounds having at least 1 form oxidation number of sulfur atoms 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 [1] to [4], wherein the content A (unit: mass ppm) of the component (A) in terms of nitrogen component based on the total amount of the composition and the content B (unit: mass ppm) of the component (B) in terms of 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], wherein 5.0 mass% or less of 1 or more kinds of polyalkyl (meth) acrylate having a weight average molecular weight of (F) more than 25,000 are contained or not contained based on the total amount of the composition.

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

[7] The lubricating oil composition according to any one of [1] to [6], wherein 1 or more polymer having a weight average molecular weight of 25,000 or less is contained or not contained in an amount of less than 0.1 mass% 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 lubrication of an electric engine.

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

Effects of the invention

The invention provides a low-viscosity lubricating oil composition with improved energy saving property, which has electric insulation property required in lubrication of an electric engine, can alleviate problems caused by lubrication of an automatic transmission and oxidative deterioration in lubrication of the electric engine, and can improve long-acting property.

Detailed Description

Hereinafter, the present invention will be described in detail. In the present specification, unless otherwise indicated, the expression "a to B" for the numerical values a and B is equivalent to "a above B below. In the case where only the value B is provided with a unit in this expression, the unit is also applicable to the value a. In this specification, "or" and "or" mean or unless otherwise indicated. In the present specification, element E ₁ E and E ₂ ，“E ₁ And/or E ₂ "this expression is equivalent to" E ₁ Or E is ₂ Or a combination thereof, with respect to N elements E ₁ 、…、E _i 、…、E _N (N is an integer of 3 or more), "E ₁ …, and/or E _N The expression "is equivalent to" E ₁ …, or E _i …, or E _N Or a combination thereof (i is a variable that can take on values that satisfy all integers 1 < i < N). In addition, "alkaline earth metal" in the present specification also includes magnesium.

In the present specification, unless otherwise specified, the contents of each element of calcium, magnesium, zinc, phosphorus, sulfur, boron, barium, and molybdenum in oil are measured by inductively coupled plasma atomic emission spectrometry (intensity contrast method (internal standard method)) based on JIS K0116. The nitrogen content in the oil was measured by a chemiluminescent method based on JIS K2609. In the present specification, "weight average molecular weight" and "number average molecular weight" refer to weight average molecular weight and number average molecular weight in terms of standard polystyrene as measured by Gel Permeation Chromatography (GPC). GPC measurement conditions were as follows.

[ GPC measurement conditions ]

The device comprises: waters Corporation ACQUITY (registered trademark) APC UV RI system

Chromatographic column: ACQUITY (registered trademark) APC 900A (gel particle diameter 2.5 μm, column size (inner diameter. Times. Length) 4.6 mm. Times.150 mm) 2 pieces and ACQUITY (registered trademark) APC 200A (gel particle diameter 2.5 μm, column size (inner diameter. Times. Length) 4.6 mm. Times.150 mm) 1 piece were connected in series in this order from the upstream side

Chromatographic column temperature: 40 DEG C

Sample solution: tetrahydrofuran solution having sample concentration of 1.0% by mass

Solution injection amount: 20.0 mu L

Eluent: tetrahydrofuran (THF)

The detection device comprises: differential refraction detector

Standard substance: standard polystyrene (Agilent Technologies Agilent EasiCal (registered trademark) PS-1) 8 kinds (molecular weight: 2698000, 597500, 290300, 133500, 70500, 30230, 9590, 2970)

When the weight average molecular weight measured under the above conditions is less than 10000, the chromatographic column and the standard substance are changed to the following conditions and then the measurement is performed.

Chromatographic column: ACQUITY (registered trademark) APC XT125A (gel particle diameter 2.5 μm, column size (inner diameter. Times. Length) 4.6 mm. Times.150 mm) 1 and ACQUITY (registered trademark) APC XT45A (gel particle diameter 1.7 μm, column size (inner diameter. Times. Length) 4.6 mm. Times.150 mm) 2 pieces of ACQUITY (registered trademark) 37 were connected in series in this order from the upstream side

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

Lubricating base oil (O)

The lubricating oil composition (hereinafter also referred to as "lubricating oil composition" or "composition") of the present invention contains a major amount of a lubricating base oil and 1 or more additives other than the base oil. The lubricating oil composition of the present invention comprises a lubricating base oil containing 1 or more mineral base oils or 1 or more synthetic base oils or a combination thereof, and has a kinematic viscosity at 40 ℃ of 6.0 to 12.0mm ² Lubricating base oils of/s (hereinafter referred to as "(O) components").

As the lubricating base oil, 1 or more mineral base oils or 1 or more synthetic base oils, or a mixed base oil thereof may 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 a mixed base oil of these may be used. The API group I base oil is a mineral oil base oil having a sulfur content of more than 0.03 mass% and/or a saturation fraction of less than 90 mass% and a viscosity index of 80 or more and less than 120. The API group II base oil is a mineral oil base oil having a sulfur content of 0.03 mass% or less, a saturation fraction of 90 mass% or more, and a viscosity index of 80 or more and less than 120. The API group III base oil is a mineral oil base oil having a sulfur content of 0.03 mass% or less, a saturation fraction of 90 mass% or more, and a viscosity index of 120 or more. The API group IV base oil is an alpha-polyolefin base oil. The API group V base oil is a base oil other than the above groups I to IV, and preferable examples thereof include ester base oils. In the present specification, the viscosity index means a viscosity index measured in accordance with JIS K2283-2000. In the present specification, the "content of sulfur component in lubricating base oil" is measured based on JIS K2541-2003. In addition, the "content of saturated fraction in lubricating base oil" in the present specification is a value measured based on ASTM D2007-93.

In one embodiment, as the (O) component, 1 or more API group II base oils, 1 or more API group III base oils, 1 or more API group IV base oils, or 1 or more API group V base oils, or a combination thereof may be preferably used.

Examples of the mineral base oil include paraffinic mineral oils obtained by refining a lubricating oil fraction obtained by atmospheric distillation and/or vacuum distillation of crude oil by a combination of 1 or 2 or more refining treatments selected from solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrofinishing, sulfuric acid washing, clay treatment, and the like, normal paraffin base oils, isoparaffin base oils, and mixtures of these, and the like. API group II base oils and group III base oils are typically manufactured via a hydrocracking process.

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

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

(2) Distillate oil (WVGO) obtained by vacuum distillation of atmospheric residue of an alkanyl-based crude oil and/or a mixed-base crude oil

(3) Waxes obtained by dewaxing a lubricating oil (slack wax) and the like, and/or synthetic waxes obtained by Fischer-Tropsch synthesis (FT) and the like (FT wax, natural gas synthesis (GTL) wax and the like)

(4) 1 base oil selected from the group consisting of base oils (1) to (3) or a mixed oil of 2 or more selected from the group consisting of base oils (1) to (3) or a light hydrocracked treated oil of these or a mixed oil of these

(5) Mixed oil of 2 or more kinds selected from base oils (1) to (4)

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

(7) Light hydrocracked oils (MHC) for base oils (6)

(8) And (3) a mixed oil of 2 or more kinds selected from the group consisting of base oils (1) to (7).

The predetermined purification method is preferably hydrorefining such as hydrocracking (hydrorefining); solvent refining such as furfural solvent extraction; dewaxing such as solvent dewaxing and catalytic dewaxing; refining with acid clay, activated clay, etc.; washing with sulfuric acid, washing with caustic soda, and other chemicals (acid or alkali). One of these purification methods may be carried out alone, or two or more of these purification methods may be carried out in combination. In addition, when two or more purification methods are combined, the order thereof is not particularly limited, and may be appropriately selected.

The mineral base oil is particularly preferably the following base oil (9) or (10) obtained by subjecting a base oil selected from the base oils (1) to (8) or a lubricating oil fraction recovered from the base oil to a predetermined treatment.

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

(10) Hydroisomerization of a base oil selected from the base oils (1) to (8) or a lubricating oil fraction recovered from the base oil, and dewaxing treatment such as solvent dewaxing and catalytic dewaxing of the product or the lubricating oil fraction recovered from the product by distillation or the like, or hydroisomerization of a base oil obtained by distilling the dewaxed base oil. The base oil produced as the dewaxing step through the catalytic dewaxing step is preferable.

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

In addition, the catalyst that can be used for the hydrocracking/hydroisomerization is not particularly limited, and preferably used is: a hydrocracking catalyst comprising a support, which is a composite oxide having a decomposition activity (for example, silica-alumina, alumina-boria, silica-zirconia, etc.) or a composite oxide obtained by bonding 1 or more kinds of the composite oxides with a binder, and a metal having a hydrogenation ability (for example, 1 or more kinds of metals of group VIa, group VIII, etc. of the periodic table) supported thereon; alternatively, a hydroisomerization catalyst comprising at least 1 or more metals having hydrogenation ability among metals of group VIII supported on a carrier comprising zeolite (e.g., ZSM-5, zeolite beta, SAPO-11, etc.). The hydrocracking catalyst and the hydroisomerization catalyst may be used in combination by lamination or mixing, etc.

The reaction conditions in hydrocracking and hydroisomerization are not particularly limited, and it is preferable that the hydrogen partial pressure is 0.1 to 20MPa, the average reaction temperature is 150 to 450℃and the LHSV is 0.1 to 3.0hr ^-1 The hydrogen/oil ratio is 50 to 20000scf/b.

From the viewpoint of further improving the viscosity-temperature characteristics of the composition and fuel-saving properties, the% C of the mineral oil base oil _P Preferably 60 or more, more preferably 65 or more, and from the viewpoint of improving the solubility of the additive, 99 or less, more preferably 95 or less, still more preferably 94 or less, and in one embodiment 60 to 99 or 60 to 95 or 65 to 94.

From the viewpoint of further improving the viscosity-temperature characteristics of the composition and fuel-saving properties, the% C of the mineral oil base oil _A Preferably 2 or less, more preferably 1 or less, still more preferably 0.8 or less, particularly preferablyIs 0.5 or less.

% C of mineral base oil from the viewpoint of improving solubility of additives _N Preferably 1 or more, more preferably 4 or more, and from the viewpoint of further improving the viscosity-temperature characteristics and fuel economy of the composition, it is preferably 40 or less, more preferably 35 or less, and in one embodiment, may be 1 to 40 or 4 to 35.

% C in the present specification _P 、％C _N % C _A Respectively means the percentage of the number of alkane carbon atoms relative to the total number of carbon atoms, the percentage of the number of cycloalkane 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, as determined by the method according to ASTM D3238-85 (n-D-M ring analysis). Namely, the above% C _P 、％C _N And% C _A The preferable range of (C) is based on the value obtained by the above method, for example, the% C obtained by the above method even if the lubricating base oil contains no naphthene component _N Values exceeding 0 may also be displayed.

The content of the saturated fraction in the mineral oil base oil is preferably 90% by mass or more, more preferably 95% by mass or more, and still 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. The saturation fraction in the present specification means a value measured according to ASTM D2007-93.

In addition, as a separation method of the saturation fraction, a similar method capable of obtaining the same result can be used. Examples of the method include the method described in ASTM D2007-93, the method described in ASTM D2425-93, the method described in ASTM D2549-91, the method using High Performance Liquid Chromatography (HPLC), and the method obtained by modifying these methods.

The aromatic component in the mineral oil base oil is preferably 0 to 10 mass%, more preferably 0 to 5 mass%, particularly preferably 0 to 1 mass%, and in one embodiment may be 0.1 mass% or more based on the total amount of the base oil. The content of the aromatic component is not more than the above-described upper limit, whereby the low-temperature viscosity property and viscosity-temperature property in a new oil state can be improved, the fuel economy can be further improved, and 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 an additive is mixed with a lubricant base oil, the effect of the additive can be effectively exerted. The lubricating base oil may be a base oil containing no aromatic component, but the solubility of the additive can be further improved by setting the content of the aromatic component to the above lower limit or more.

The aromatic component in the present specification means a value measured according to ASTM D2007-93. The aromatic component generally contains anthracene, phenanthrene, and an alkylate thereof, in addition to alkylbenzene and alkylnaphthalene, and further contains a compound obtained by condensing four or more benzene rings, an aromatic compound having a heteroatom such as pyridines, quinolines, phenols, naphthols, and the like.

Examples of the API group IV base oil include ethylene-propylene copolymers, polybutenes, 1-octene oligomers, 1-decene oligomers, hydrogenated products thereof, and alpha-olefin oligomers and low copolymers having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms, and hydrogenated products thereof.

Preferred examples of the API group V base oil include 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.); and ester base oils such as polyol esters (e.g., trimethylolpropane octanoate, trimethylolpropane nonanoate, pentaerythritol-2-ethylhexanoate, pentaerythritol nonanoate, etc.). Examples of the API group V base oil include aromatic synthetic base oils such as alkylbenzene, alkylnaphthalene, polyoxyalkylene glycol, dialkyldiphenyl ether, and polyphenylene ether.

Lubricating base oils (total base oils) are based on the viewpoint of improving electrical insulation properties of new oils, and on the viewpoint of improving wear resistance by sufficiently forming an oil film at a lubricating siteKinematic viscosity at 40℃of 6.0mm ² Above/s, preferably 6.5mm ² Higher than/s, more preferably 7.0mm ² At least/s, and from the viewpoint of fuel-saving property and low-temperature viscosity characteristics of the lubricating oil composition, is 12.0mm ² And/s or less, in one embodiment may be 6.0 to 12.0mm ² /s, or 6.5-12.0 mm ² /s, or 7.0-12.0 mm ² And/s. In the present specification, "kinematic viscosity at 40℃" means kinematic viscosity at 40℃measured by using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument company) as a measuring device based on JIS K2283-2000.

The kinematic viscosity of the lubricating base oil (total base oil) at 100℃is preferably 1.9mm from the viewpoint of further improving the electrical insulation properties of the new oil and the viewpoint of further improving the wear resistance by sufficiently forming an oil film at the lubricating site ² Higher than/s, more preferably 2.0mm ² Higher than/s, more preferably 2.1mm ² In addition, from the viewpoint of further improving fuel economy, it is preferably 3.5mm or more ² Less than/s, more preferably 3.4mm ² Preferably 3.3mm or less ² And/s or less, in one embodiment may be 1.9 to 3.5mm ² /s, or 2.0-3.4 mm ² /s, or 2.1-3.3 mm ² And/s. In the present specification, "kinematic viscosity at 100" means kinematic viscosity at 100℃measured by using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument company) as a measuring device based on JIS K2283-2000.

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 from the viewpoint of improving the viscosity-temperature characteristics of the composition and further improving fuel economy and wear resistance. The viscosity index in the present specification means a viscosity index measured by using an automatic viscometer (trade name "CAV-2100", manufactured by Cannon Instrument company) as a measuring device based on JIS K2283-2000.

The pour point of the lubricating base oil (total base oil) is preferably-10 ℃ or lower, more preferably-12.5 ℃ or lower, further preferably-15 ℃ or lower, particularly preferably-17.5 ℃ or lower, most preferably-20.0 ℃ or lower, from the viewpoint of low-temperature fluidity of the lubricating oil composition as a whole. The pour point in the present specification means a pour point measured in accordance with JIS K2269-1987.

The sulfur content of the base oil depends on the sulfur content of the feedstock. For example, when a raw material containing substantially no sulfur, such as a synthetic wax component obtained by a fischer-tropsch reaction, is used, a base oil containing substantially no sulfur can be obtained. In addition, when a sulfur-containing raw material such as slack wax obtained through a process of refining a base oil or microcrystalline wax obtained through a process of refining a refined wax is used, the sulfur component in the obtained base oil is usually 100 mass ppm or more. The sulfur content in the lubricating base oil (total base oil) is usually 0.03 mass% or less, and preferably 0.01 mass% or less from the viewpoint of oxidation stability. The content of the sulfur component in the base oil in the present specification means the amount of sulfur measured based on JIS K2541-2003.

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

In one embodiment, the lubricating oil base oil may comprise 80 to 100 mass%, or 90 to 99 mass%, or 95 to 99 mass%, based on the total base oil, of 1 or more API group II base oils, 1 or more API group III base oils, or 1 or more API group IV base oils, or a combination thereof. In one embodiment, the lubricating oil base oil may comprise from 80 to 100 mass%, or from 90 to 99 mass%, or from 95 to 99 mass%, based on the total base oil, of 1 or more API group III base oils, or 1 or more API group IV base oils, or a combination thereof. The lubricating base oil may or may not contain an API group V base oil. In one embodiment, the content of the API group V base oil of 1 or more kinds in the lubricating base oil is preferably 0 to 20 mass% or 0 to 10 mass% based on the total amount of the base oil, and may be 1 to 10 mass% or 1 to 5 mass% based on the viewpoint of improving the fatigue resistance. The lubricating base oil may or may not contain an API group IV base oil. In one embodiment, the content of the API group IV base oil of 1 or more 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 may be 75 to 97% by mass, based on the total amount of the lubricating oil composition.

(A) 1 st succinimide compound

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

[ chemical formula 1 ]

In the general formula (2), R ¹ A represents a polyisobutenyl 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 one typical embodiment, the compound represented by the general formula (2) is obtained as a mixture of compounds having different a. In one embodiment, R is based on the standpoint of solubility in the base oil ¹ The number of carbon atoms of (2) is preferably 40 or more, more preferably 60 or more, and is preferably 400 or less, more preferably 350 or less, still more preferably from the viewpoint of low-temperature fluidity of the compositionIs selected to be 250 or less and may be 40 to 400, or 60 to 350, or 60 to 250 in one embodiment.

In the general formula (3), R ² R is as follows ³ Each independently represents a polyisobutenyl group having a number average molecular weight of 800 or more, and may be a combination of different groups. B represents an integer of 0 to 15, preferably 1 to 13, 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, R is based on the standpoint of solubility in the base oil ² R is as follows ³ The number of carbon atoms of (a) is preferably 40 or more, more preferably 60 or more, and in view of the low-temperature fluidity of the composition, it is preferably 400 or less, more preferably 350 or less, still more preferably 250 or less, and may be 40 to 400, or 60 to 350, or 60 to 250 in one embodiment.

(A) Polyisobutenyl (R) ¹ ～R ³ ) Is a branched alkyl or alkenyl group derived from an oligomer of isobutylene (polyisobutylene). Polyisobutenyl succinic anhydrides can be obtained, for example, by reacting polyisobutenes having a c=c double bond with maleic anhydride at from 100 to 200 ℃. The polyisobutenyl group of the polyisobutenyl succinic anhydride obtained by this reaction is an alkenyl group having a c=c double bond. The alkenyl succinic anhydride is further subjected to a hydrogenation reaction to obtain a polyisobutenyl succinic anhydride in which the polyisobutenyl group is in an alkyl form.

Polyisobutenyl (R) in component (A) from the viewpoint of improving oil solubility ¹ ～R ³ ) The number average molecular weight of (2) is 800 or more, preferably 900 or more, and is preferably 3500 or less, in one embodiment 800 to 3500 or 900 to 3500, from the viewpoint of improving the low-temperature fluidity of the lubricating oil. (A) Number average molecular weight Mn of polyisobutenyl groups of the component ^PIB Number average molecular weight Mn based on the corresponding polyisobutenyl succinic acid ^SA Can be calculated by the following expression (4).

Mn ^PIB ＝Mn ^SA -117.08…(4)

In the present specification, the number average molecular weight of polyisobutenyl succinic acid refers to a number average molecular weight in terms of standard polystyrene measured based on Gel Permeation Chromatography (GPC), and the measurement method thereof is as described above. When a certain component (A) is imparted, the number average molecular weight of the polyisobutenyl group in the component (A) can be determined by the following procedure.

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

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

(3) A step of obtaining an organic solvent solution of polyisobutenyl succinic acid by washing the organic phase obtained in (2) with an acidic aqueous solution (e.g., dilute hydrochloric acid, etc.), removing polyamine and its base (if present) from the organic phase;

(4) Number average molecular weight Mn of polyisobutenyl succinic acid obtained by (3) ^SA A step of measuring by GPC;

(5) Based on the number average molecular weight Mn of the polyisobutenyl succinic acid obtained by (4) ^SA The number average molecular weight Mn of the polyisobutenyl group is calculated by the above formula (4) ^PIB Is carried out by a method comprising the steps of.

The polyisobutenyl succinimide includes a mono-type succinimide represented by the general formula (2) in which only one end of the polyamine chain is imidized, and a bis-type succinimide represented by the general formula (3) in which both ends of the polyamine chain are imidized. The lubricating oil composition may contain either one of a mono-type succinimide and a bis-type succinimide, or may contain a mixture of both. The content of the bis-succinimide or a modified product thereof in the 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 the component (A).

The condensation product (i.e., unmodified succinimide) may be used as the component (a), or the condensation product may be modified to be used as a modified product (derivative) described later. The condensation product of polyisobutenyl succinic acid or an anhydride thereof and a polyamine may be a bis-type succinimide in which both ends of a polyamine chain are imidized (refer to formula (3)), a mono-type succinimide in which only one end of a polyamine chain is imidized (refer to formula (2)), or a mixture of these. Examples of the polyamine include polyethylene polyamines having 3 to 17 nitrogen atoms such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, heptaethyleneoctamine, octaethylenenonamine, nonaethylenedecamine, decaethyleneundecylamine, undecylenedodecamine, dodecaethylenetridecylamine, tridecetylenetetramine, tetradecylenepentadecylamine, pentadecylenehexadecylamine and hexadecyleneheptadecylamine, and mixtures of these, and polyamine raw materials containing 1 or more selected from these can be preferably used. In one embodiment, a polyamine starting material containing 1 or more polyethylene polyamines having 3 to 17, or 3 to 15, or 3 to 13 nitrogen atoms can be preferably used. In one other embodiment, a polyamine starting material containing 1 or more polyethylene polyamines having 3 to 11 or 3 to 7 nitrogen atoms may be preferably used. Commercially available polyethylene polyamines, typically a mixture of 2 or more polyethylene polyamines having a continuous number of nitrogen atoms, may be preferably used as the polyamine raw material in the production of component (a). Further, although the structures of condensation reaction products of polyisobutenyl succinic acid or an anhydride thereof and linear polyethylene polyamines are shown in the general formulae (2) and (3), commercially available polyethylene polyamines having 4 or more nitrogen atoms may generally contain branched polyethylene polyamines having the same nitrogen atom number as structural isomers in addition to the linear polyethylene polyamines. The common point of branched polyethylene polyamine and linear polyethylene polyamine is that each group of 2 adjacent amine groups is linked via ethylene group. A branched polyethylene polyamine having k (k is an integer of 1 to n-3 or less) branched nitrogen atoms, which has a number n of nitrogen atoms, has 2+k primary amine groups, n-2 to 2k secondary amine groups and k tertiary amine groups, as compared with a linear polyethylene polyamine having a number n of nitrogen atoms (n is an integer of 2 or more) having 2 primary amine groups and n-2 secondary amine groups. The polyethylene polyamine mixture containing such a branched structure isomer can be preferably used as a polyamine raw material in the production of the component (a), and a condensation reaction product of such a branched polyethylene polyamine and polyisobutenyl succinic acid or an anhydride thereof and a modified product thereof are also contained in the component (a). In general formulae (2) and (3), succinimides in which 1 or 2 primary amine groups are imidized are shown, but in the condensation reaction of a branched polyethylene polyamine having k branches with polyisobutenyl succinic acid or an anhydride thereof, up to 2+k primary amine groups may be imidized. The condensation reaction product (succinimide compound) in which 3 or more primary amine groups are imidized and its modified product are also included in the component (a). The polyamine raw material may further contain ethylenediamine, or may not contain ethylenediamine, and 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, from the viewpoint of improving the performance of the condensation product or its modified product as a dispersant. The succinimide obtained as a product of a condensation reaction of a mixture of polyisobutenyl succinic acid or an anhydride thereof and 2 or more polyamines is a mixture containing 2 or more compounds having a different a or b in the general formula (2) or (3). The condensation reaction of polyisobutenyl succinic acid or anhydride thereof with a polyamine may be carried out, for example, in an organic solvent (e.g., toluene, etc.) which forms an azeotropic mixture with water. That is, the solution of the mixture of polyisobutenyl succinic acid or an anhydride thereof and a polyamine is refluxed and stirred, and water produced as the condensation reaction proceeds is removed by azeotropic distillation with a solvent, whereby a condensation reaction product can be easily obtained. The reaction molar ratio in the condensation reaction of polyisobutenyl succinic acid or anhydride thereof with polyamine may be, for example, polyisobutenyl succinic acid or anhydride thereof: polyamine = 1: 10-10: 1. or 1: 5-5: 1.

(A) The weight average molecular weight of the component (A) is preferably 1000 to 20000, more preferably 2000 to 20000, still more preferably 3000 to 15000, and in one embodiment 4000 to 15000.

Examples of the modified product (modified compound, derivative) of polyisobutenyl succinimide include (i) a modified product via an oxygen-containing organic compound, (ii) a boric acid modified product, (iii) a phosphoric acid modified product, (iv) a sulfur modified product, and (v) a modified product via a combination of 2 or more of these.

(i) The modified product obtained by reacting the above polyisobutenyl 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 acid anhydride or ester compound of these, an alkylene oxide having 2 to 6 carbon atoms, or a hydroxy (poly) oxyalkylene carbonate to neutralize or amidate a part or all of the remaining amine groups and/or imine groups.

(ii) The boric acid-modified substance is a modified compound obtained by reacting boric acid with the polyisobutenyl succinimide, and neutralizing or amidating 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 the polyisobutenyl succinimide with phosphoric acid 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 polyisobutenyl succinimide with a sulfur compound.

(v) The modified compound obtained by the combination of 2 or more modifications can be obtained by subjecting the polyisobutenyl succinimide to a combination of 2 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 these modified products (derivatives) of (i) to (v), boric acid-modified compounds, particularly boric acid-modified products of bis-polyisobutenyl succinimides, can be preferably used.

The content of the component (a) in the lubricating oil composition may be 80 mass ppm or more, preferably 100 mass ppm or more, based on the total amount of the composition, based on the nitrogen component, from the viewpoint of improving the electrical insulation properties of the composition after oxidative deterioration and the viewpoint of reducing the acid value of the composition after oxidative deterioration, and may be 2.7 mass% or less, preferably 2.5 mass% or less, based on the total amount of the composition, and may be 2.3 mass% or less, in one embodiment, based on the total amount of the composition, from the viewpoint of improving the fuel economy.

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 amount of the compounds is 16,000 or less, preferably 15,000 or less, and may be 14,000 or less in one embodiment, from the viewpoint of reducing the viscosity of the composition and improving fuel economy. (A) 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 (a) component and the content (mass%) based on the total (a) component.

(B) 2 nd succinimide Compound

The lubricating oil composition of the present invention is 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 with a polyamine or a modified product thereof, or a combination thereof (hereinafter also referred to as "(component B")) which contains 50 to 1300 mass ppm in terms of nitrogen component based on the total amount of the composition. The condensation reaction product (condensation product) is an alkyl or alkenyl succinimide, and can be represented by the following general formula (5) or (6).

[ chemical formula 2 ]

In the general formulae (5) and (6), R ⁴ ～R ⁶ Each independently represents 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. R is R ⁷ R is as follows ⁸ Each independently represents 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 still more preferably 1 to 4. d represents an integer of 1 to 7, preferably 1 to 4, more preferably 1 to 3.

(B) The component (c) is a condensation reaction product (condensation product) obtained by reacting an alkyl or alkenyl succinic acid having an alkyl or alkenyl group having 8 to 30 carbon atoms, preferably 12 to 28 carbon atoms, or an anhydride thereof, with a polyamine. The component (B) may be used as it is (i.e., unmodified succinimide), or may be converted into a modified product (derivative) to be described later. The condensation product of the alkyl or alkenyl succinic acid or an anhydride thereof and the polyamine may be a bis-type succinimide in which both ends of the polyamine chain are imidized (see formula (6)), may be a mono-type succinimide in which only one end of the polyamine chain is imidized (see formula (5)), or may be a mixture of these. Examples of the polyamine include polyethylene polyamines having 3 to 9 nitrogen atoms such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, heptaethyleneoctamine and octaethylenenonamine, ethylenediamine and mixtures thereof, and polyamine raw materials containing 1 or more kinds selected from these are preferably used. In one embodiment, a polyamine starting material containing 1 or more polyethylene polyamines having 3 to 9, or 3 to 6, or 3 to 5 nitrogen atoms may be preferably used. In one other embodiment, a polyamine raw material containing 1 or more kinds of polyethylene polyamines or ethylenediamine having 3 to 8, or 3 to 7, or 3 to 6, or 3 to 5 nitrogen atoms, or a combination thereof may be preferably used. Commercially available polyethylene polyamines, typically a mixture of 2 or more polyethylene polyamines having a continuous number of nitrogen atoms, may be preferably used as the polyamine raw material in the production of component (B). Further, the general formulae (5) and (6) show the structure of a condensation reaction product of an alkyl or alkenyl succinic acid or an anhydride thereof and a linear polyethylene polyamine, and as described above in relation to the component (a), a commercially available polyethylene polyamine having 4 or more nitrogen atoms may generally contain a branched polyethylene polyamine having the same nitrogen atom number as a structural isomer in addition to the linear polyethylene polyamine. The polyethylene polyamine mixture containing such a branched structure isomer can be preferably used as a polyamine raw material in the production of the component (B), and a condensation reaction product of such a branched polyethylene polyamine and an alkyl or alkenyl succinic acid or an acid anhydride thereof and a modified product thereof can be also contained in the component (B). In general formulae (5) and (6), succinimides in which 1 or 2 primary amine groups are imidized are shown, but in the condensation reaction of branched polyethylene polyamine having k branches with alkyl or alkenyl succinic acid or an anhydride thereof, up to 2+k primary amine groups may be imidized. The condensation reaction product (succinimide compound) in which 3 or more primary amine groups are imidized and its modified products are also included in the component (B). The polyamine raw material may contain ethylenediamine, or may not contain ethylenediamine, and 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, from the viewpoints of improving the performance of the condensation product or its modified product as a friction modifier and improving the oxidation deterioration resistance. The succinimide obtained as a product of a condensation reaction of a mixture of an alkyl or alkenyl succinic acid or an anhydride thereof and 2 or more polyamines is a mixture containing 2 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 anhydride thereof with the polyamine may be carried out, for example, in an organic solvent (e.g., toluene, etc.) which forms an azeotropic mixture with water. That is, the solution of a mixture of alkyl or alkenyl succinic acid or an anhydride thereof and a polyamine is refluxed and stirred, and water produced as the condensation reaction proceeds is removed by azeotropic distillation with a solvent, whereby a condensation reaction product can be easily obtained. The reaction molar ratio in the condensation reaction of the alkyl or alkenyl succinic acid or anhydride thereof with the polyamine may be, for example, alkyl or alkenyl succinic acid or anhydride thereof: polyamine = 1: 10-10: 1. or 1: 5-5: 1.

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

(B) Components having high polarity, such as a component and a metal-based cleaning agent, tend to reduce the electrical insulation properties of the new oil and the composition after oxidative deterioration. However, the present inventors have found that by combining the component (a) and the component (B) in the respective predetermined content ranges, it is possible to reduce the content of the component (a) to improve energy saving properties and to reduce the increase in acid value of the oxidation-modified oil without largely losing the electrical insulation properties of the new oil and the composition after oxidation-modification.

The content of the component (B) in the lubricating oil composition is 50 mass ppm or more based on the total amount of the composition in terms of nitrogen component from the viewpoint of reducing the increase in acid value of the oxidation-modified oil, and 1300 mass ppm or less from the viewpoint of improving the electrical insulation property of the oxidation-modified oil.

The relationship represented by the following formula (1) is preferably satisfied in terms of reducing the content of component (a), improving energy saving properties, reducing the increase in acid value of the oxidation-modified oil without largely losing the electrical insulation properties of the new oil and the composition after oxidation-modification, and in terms of the content a (unit: mass ppm) of component (a) in terms of nitrogen component based on the total amount of the composition and the content B (unit: mass ppm) of component (B) in terms of nitrogen component based on the total amount of the composition. The function max in the following equation (1) is a function of the maximum value of the argument. That is, f (a) > 50 max (50, f (a))=f (a), f (a) < 50 max (50, f (a))=50, f (a) =50 max (50, f (a))=50.

[ number 2 ]

B≥max 50,f(A))

(C) calcium-based cleaning agent

In a preferred embodiment, the lubricating oil composition may further contain 1 or more calcium carbonate overbased calcium sulfonate detergent (hereinafter also referred to as "(C1) component") or 1 or more calcium carbonate overbased calcium salicylate detergent (hereinafter also referred to as "(C2) component"), or a combination thereof (hereinafter also referred to as "(C) component"). (C) The component (C1) may be contained only, or the component (C2) may be contained only, or both of the component (C1) and the component (C2) may be contained.

As a preferable example of the (C1) calcium carbonate overbased calcium sulfonate detergent, an overbased salt of a calcium salt of an alkylaromatic sulfonic acid obtained by sulfonating an alkylaromatic compound may be mentioned. The weight average molecular weight of the alkylaromatic compound is preferably 300 to 1500, more preferably 400 to 1300.

Examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid. Examples of the petroleum sulfonic acid described herein include those obtained by sulfonating alkylaromatic compounds in a lubricating oil fraction of a mineral oil, petroleum sulfonic acid (mahogany acid) which is a by-product in the production of white oil, and the like. Examples of the synthetic sulfonic acid include a product obtained by recovering byproducts from a production facility of alkylbenzene as a raw material of a detergent, and a product obtained by sulfonating alkylbenzene having a linear or branched alkyl group obtained by alkylating benzene with a polyolefin. As other examples of the synthetic sulfonic acid, products obtained by sulfonating an alkyl naphthalene such as dinonyl naphthalene may be mentioned. The sulfonating agent used in sulfonation of these alkylaromatic compounds is not particularly limited, and fuming sulfuric acid or anhydrous sulfuric acid may be used, for example.

(C2) The calcium carbonate overbased calcium salicylate detergents are overbased salts of calcium salicylate. As a preferred example of the calcium salicylate, there is calcium salicylate represented by the following general formula (7).

[ chemical 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. When e=2, R ⁹ Combinations of different groups are possible.

The method for producing calcium salicylate is not particularly limited, and a known method for producing monoalkylsalicylate can be used. For example, calcium salicylate can be obtained by alkylating phenol as a starting material with an olefin, then carboxylating the resultant product with carbon dioxide or the like to obtain monoalkylsalicylic acid, alkylating salicylic acid as a starting material with an equivalent amount of the above olefin to obtain monoalkylsalicylic acid, reacting the monoalkylsalicylic acid with a calcium base such as an oxide or hydroxide of calcium, or subjecting the monoalkylsalicylic acid to metal exchange with a calcium salt after forming an alkali metal salt such as a sodium salt or potassium salt.

The method for obtaining the calcium carbonate overbased calcium sulfonate or calcium salicylate is not particularly limited, and for example, 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.

The base numbers of the (C1) component and the (C2) component are preferably 200mgKOH/g or more, more preferably 250mgKOH/g or more from the viewpoint of improving the wear resistance, the seizure resistance and the torque transmission capacity of the wet clutch, and are preferably 600mgKOH/g or less, more preferably 550mgKOH/g or less from the same viewpoint, and may be 200 to 600mgKOH/g, or 250 to 550mgKOH/g in one embodiment. When the component (C1) contains 2 or more kinds of calcium carbonate overbased calcium sulfonate detergents, the base number of each calcium carbonate overbased calcium sulfonate detergent is preferably in the above range. Similarly, when the component (C2) contains 2 or more kinds of calcium carbonate overbased calcium salicylate detergents, the base number of each calcium carbonate overbased calcium salicylate detergent is preferably within the above range. The base number in the present specification means a base number measured by the perchloric acid method according to JIS K2501. In addition, the metal-based cleaning agent is generally obtained by a reaction in a diluent such as a solvent or a lubricating oil base oil. For this reason, the metal-based cleaning agent is commercially distributed in a state diluted with a diluent such as a lubricating oil base oil. In the present specification, the base number of the metal-based detergent means the base number in the state of containing the diluent.

When the component (C) is contained in the lubricating oil composition, the content ((C) content is preferably less than 100 mass ppm, more preferably 95 mass ppm or less, or 90 mass ppm or less, in one embodiment, based on the total amount of the composition, from the viewpoint of further improving the electrical insulation property and fuel-saving property of the new oil and the viewpoint of improving fatigue resistance, and from the viewpoint of improving the wear resistance, the seizure resistance, the fatigue resistance, and the torque transmission capacity of the wet clutch, is preferably 10 mass ppm or more, more preferably 15 mass ppm or more, and from the viewpoint of improving the wear resistance, the seizure resistance, the fatigue resistance, and the torque transmission capacity of the wet clutch, is preferably 20 mass ppm or more, and from the viewpoint of improving the wear resistance, the seizure resistance, the fatigue resistance, and the torque transmission capacity of the wet clutch, is preferably 10 mass ppm or more to less than 100 mass ppm, or from 10 to 95 mass ppm, or from 15 to 90 mass ppm, or from the viewpoint of improving the total mass ppm or from the total mass of the composition.

In general, in the field of lubricating oils, as a metal-based detergent, an organic acid metal salt capable of forming micelles (for example, alkali metal or alkaline earth metal alkylsalicylate, alkali metal or alkaline earth metal alkylbenzenesulfonate, alkali metal or alkaline earth metal alkylphenate, etc.) or a mixture of the organic acid metal salt and an alkali metal salt (for example, hydroxide, carbonate, borate, etc. of alkali metal or alkaline earth metal constituting the organic acid metal salt) is used. Such an organic acid generally has at least 1 polar group (for example, carboxyl group, sulfo group, phenolic hydroxyl group, etc.) having bronsted acidity capable of forming a salt with a metal base (typically, metal oxide and/or metal hydroxide) and at least 1 lipophilic group (for example, linear or branched alkyl group having 6 or more carbon atoms, etc.) such as linear or branched alkyl group in one molecule, and the like. The soap group of the metal-based detergent means a conjugated base of an organic acid constituting a soap component of the metal-based detergent (for example, an alkyl salicylic acid anion in the case of a salicylate detergent, for example, an alkyl benzenesulfonic acid anion in the case of a sulfonate detergent, and for example, an alkyl phenolate anion in the case of a phenolate detergent).

The lubricating oil composition of the present invention may further contain 1 or more metal-based detergents other than the component (C), or may be free of them. However, the total content of all the metal-based detergents containing the 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, in one embodiment 80 mass ppm or less, based on the total amount of the composition in terms of metal, from the viewpoint of further improving the electrical insulation properties, fuel economy and fatigue resistance of the new oil, and from the viewpoint of further improving the wear resistance, preferably 10 mass ppm or more, in one embodiment 20 mass ppm or more, and in one embodiment 10 mass ppm or less than 100 mass ppm, or 10 to 95 mass ppm, or 15 to 95 mass ppm, or 20 to 80 mass ppm, based on the total amount of the composition. In one embodiment, the lubricating oil composition of the present invention may be a lubricating oil composition containing no metal-based detergent other than the component (C).

Antioxidant (D)

In a preferred embodiment, the lubricating oil composition may further contain 1 or more amine-based antioxidants (hereinafter also referred to as "(D) components") and 1 or more phenol-based antioxidants (hereinafter also referred to as "(D2) components") as antioxidants (hereinafter also referred to as "(D) components").

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

Examples of the hindered amine-based antioxidant include compounds having a 2, 6-tetraalkylpiperidine skeleton (2, 6-tetraalkylpiperidine derivatives). As the 2, 6-tetraalkylpiperidine derivative, a 2, 6-tetraalkylpiperidine derivative having a substituent at the 4-position is preferable. Alternatively, 2, 6-tetraalkylpiperidine skeletons may be bonded to each other via substituents at their respective 4-positions. The N-position of the 2, 6-tetraalkylpiperidine skeleton may be unsubstituted or substituted with an alkyl group having 1 to 4 carbon atoms. The 2, 6-tetraalkylpiperidine skeleton is preferably a 2, 6-tetramethylpiperidine skeleton.

Examples of the substituent at the 4-position of the 2, 6-tetraalkylpiperidine skeleton include acyloxy (R ¹⁰ COO-), alkoxy (R) ¹⁰ O-), alkylamino (R) ¹⁰ NH-), amido (R) ¹⁰ CONH-) and the like. R is R ¹⁰ Preferably 1 to 30 carbon atoms, more preferably 1 to 24 carbon atoms, and still more preferably 1 to about 10 carbon atoms20. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, a cycloalkyl group, an alkylcycloalkyl group, an aryl group, an alkylaryl group, an arylalkyl group, and the like.

As the substituents for bonding 2, 6-tetraalkylpiperidine skeletons via the substituents at their respective 4-positions, there may be mentioned hydrocarbylenebis (carbonyloxy) (-OOC-R) ¹¹ -COO-), hydrocarbylene diamino (-HN-R) ¹¹ -NH-), hydrocarbylene bis (carbonylamino) (-HNCO-R ¹¹ -CONH-) and the like. R is R ¹¹ The alkylene group having 1 to 30 carbon atoms is preferable, and the alkylene group is more preferable.

As the substituent at the 4-position of the 2, 6-tetraalkylpiperidine skeleton, an acyloxy group is preferable. Examples of the compound having an acyloxy group at the 4-position of the 2, 6-tetraalkylpiperidine skeleton include esters of 2, 6-tetramethyl-4-piperidinol and carboxylic acid. Examples of the carboxylic acid include linear or branched aliphatic carboxylic acids having 8 to 20 carbon atoms.

Examples of the component (D2) (phenol-based antioxidant) include 4,4' -methylenebis (2, 6-di-t-butylphenol); 4,4' -bis (2, 6-di-tert-butylphenol); 4,4' -bis (2-methyl-6-tert-butylphenol); 2,2' -methylenebis (4-ethyl-6-tert-butylphenol); 2,2' -methylenebis (4-methyl-6-tert-butylphenol); 4,4' -butylidenebis (3-methyl-6-tert-butylphenol); 4,4' -isopropylidenebis (2, 6-di-tert-butylphenol); 2,2' -methylenebis (4-methyl-6-nonylphenol); 2,2' -isobutylidenebis (4, 6-dimethylphenol); 2,2' -methylenebis (4-methyl-6-cyclohexylphenol); 2, 6-di-tert-butyl-4-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; hindered phenol compounds such as 3-methyl-5-t-butyl-4-hydroxyphenol fatty acid esters and bisphenol compounds. Examples of 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate 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; cetyl-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 mass% or more, more preferably 0.2 mass% or more, and in one embodiment 0.3 mass% or more, based on the total amount of the component (D1) and the component (D2), from the viewpoint of reducing the increase in the acid value of the composition after oxidative deterioration, and is preferably 3.0 mass% or less, more preferably 2.5 mass% or less, and in one embodiment 2.3 mass% or less, and in one embodiment 0.1 to 3.0 mass%, or 0.2 to 2.5 mass%, or 0.3 to 2.3 mass%, 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 deterioration.

(E) phosphorus or sulfur-containing additives

In a preferred embodiment, the lubricating oil composition may further contain 1 or more phosphorus-containing compounds (hereinafter also referred to as component (E1)), or 1 or more sulfur-containing compounds (hereinafter also referred to as component (E2)) containing at least 1 sulfur atom having a formal oxidation number of +ii or less in 1 molecule, or a combination thereof (hereinafter also referred to as component (E)).

As the component (E1), a phosphorus-containing compound functioning as an anti-wear agent or an extreme pressure agent in lubricating oil can be used. As the component (E1), 1 kind of phosphorus-containing compound may be used alone, or 2 or more kinds of phosphorus-containing compounds may be used in combination.

Examples of the component (E1) include phosphites, thiophosphites, dithiophosphites, trithiophosphites, phosphates, thiophosphates, dithiophosphates, trithiophosphates, amine salts thereof and metal salts thereof.

These phosphoric acid esters generally 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 an alkyl group, a cycloalkyl group, an alkyl-substituted cycloalkyl group, an alkenyl group, an aryl group, an alkyl-substituted aryl group, and an aryl-substituted alkyl group. These alkyl groups may be linear or branched.

Examples of the phosphoric acid-containing ester salt include a salt obtained by neutralizing part or all of the residual acidic hydrogen by reacting a metal base or a nitrogen-containing compound such as an amine compound having only ammonia, a hydrocarbon group having 1 to 8 carbon atoms, or a hydrocarbon group having a hydroxyl group in the molecule with a partial phosphate, a partial monothiophosphate, a partial dithiophosphate, a partial trithiophosphate, a partial phosphite, a partial thiophosphite, or a partial dithiophosphite.

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

[ chemical formula 4 ]

In the general formula (8), R ¹² R is as follows ¹³ Each independently represents 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).

[ chemical 5 ]

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

As used herein, "phosphorous acid" refers to the oxo acid H of phosphorus having an oxidation number of +III ₃ PO ₃ . The phosphite compound represented by the general formula (8) generally has tautomerism, and any tautomer of the compound represented by the general formula (8) in this specification belongs to the (E1) component.

In one embodiment, R is ¹² R is as follows ¹³ Preferable examples of (2) include a linear alkyl group having 4 to 18 carbon atoms. Examples of the linear alkyl group include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups.

In one embodiment, R is ¹² R is as follows ¹³ Examples of the preferable ones of (3) are 3-thiapentyl, 3-thiahexyl, 3-thiaheptyl, 3-thiaoctyl, 3-thianonyl, 3-thiadecyl, 3-thiaundecyl, 4-thiahexyl, 3-oxapentyl, 3-oxahexyl, 3-oxaheptyl, 3-oxaoctyl, 3-oxanonyl, 3-oxadecyl, 3-oxaundecyl, 3-oxadodecyl, 3-oxatridecyl, 3-oxatetradecyl, 3-oxapentadecyl, 3-oxahexadecyl, 3-oxaheptadecyl, 3-oxanonadecyl, 4-oxahexyl, 4-oxaheptyl and 4-oxaoctyl.

As the component (E2), a sulfur-containing compound functioning as an antiwear agent or an extreme pressure agent in lubricating oil can be used. Such sulfur-containing compounds contain at least 1 sulfur atom having a formal oxidation number of not more than +II in 1 molecule. In the present specification, the formal oxidation number of a sulfur atom is determined based on the relationship between the electronegativity of an atom bonded to the sulfur atom and the electronegativity of the sulfur atom. That is, in the bonding of the sulfur atom and the atom X, if the electronegativity of the element X is larger than that of sulfur, electrons considered to participate in the bonding between the two atoms are all attributed to the atom X. In contrast, in the bonding of the sulfur atom and the atom X, if the electronegativity of the element X is smaller than that of sulfur, electrons considered to participate in the bonding between the two atoms are all attributed to the sulfur atom. The oxidation number of the bonds between the sulfur atoms does not change. In the present specification, the electronegativity of all elements including sulfur is applicable to the electronegativity of all-Rochow.

Examples of the component (E2) include thiadiazole compounds, sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dialkyl (poly) sulfides, alkylthio carbamoyl compounds, thio urethane compounds, thio terpene compounds, dialkyl thiodipropionate compounds, sulfurized mineral oils, zinc dithiourethane compounds, molybdenum dithiourethane compounds, sulfolane compounds, and the like. As the component (E2), 1 kind of sulfur-containing compound may be used alone, or 2 or more kinds of sulfur-containing compounds may be used in combination.

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

[ 6 ] A method for producing a polypeptide

[ chemical 7 ]

[ chemical formula 8 ]

(in the general formulae (10) to (12), R ¹⁶ R is as follows ¹⁷ 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 thiadiazole compounds, those represented by any one of the above general formulae (10) to (12) are particularly preferably used.

The vulcanized grease is a product obtained by reacting sulfur or a sulfur-containing compound with grease (lard, whale oil, vegetable oil, fish oil, etc.). The sulfur content in the vulcanized oil and fat 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 and the like.

Examples of the sulfurized ester include methyl sulfurized oleate and octyl sulfurized rice bran fatty acid, which are obtained by sulfurizing an unsaturated fatty acid ester (for example, a product obtained by reacting an unsaturated fatty acid (oleic acid, linoleic acid, or a fatty acid extracted from the above animal or vegetable oils and fats) with various alcohols by any method.

Examples of the sulfurized olefin include a compound represented by the following general formula (13). The compound can be obtained by reacting an olefin having 2 to 15 carbon atoms or a 2 to 4 polymer thereof with a vulcanizing agent such as sulfur or sulfur chloride. As the olefin, propylene, isobutylene, diisobutylene, and the like can be preferably used.

[ chemical formula 9 ]

R ¹⁸ -S _h -R ¹⁹ (13)

(in the general formula (13), R ¹⁸ Represents an alkenyl group having 2 to 15 carbon atoms, R ¹⁹ 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). Here, R is ¹⁵ R is as follows ¹⁶ When alkyl, it is called an alkyl sulfide.

[ chemical formula 10 ]

R ² 0-S _i -R ²¹ (14)

(in the general formula (14), R ²⁰ R is as follows ²¹ The alkyl groups may be the same or different and each independently represents an alkyl group having 1 to 20 carbon atoms (which may be a straight chain or branched chain, 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 arylalkyl group having 7 to 20 carbon atoms, and i represents an integer of 1 to 8. )

Examples of the alkylthio carbamoyl compound include a compound represented by the following general formula (15).

[ chemical formula 11 ]

(in the general formula (15), R ²² ～R ²⁵ 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 alkylthio urethane compound include compounds represented by the following general formula (16).

[ chemical formula 12 ]

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

As the sulfur terpene compound, for example, reactants of phosphorus pentasulfide and pinene can be cited.

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

The sulfurized mineral oil is a substance obtained by dissolving elemental sulfur in mineral oil. The mineral oil used in the vulcanized mineral oil is not particularly limited, and examples thereof include paraffinic mineral oil, naphthenic mineral oil, and the like, which are purified by a suitable combination of known purification treatments, on a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation. The elemental sulfur may be in any form such as a lump, a powder, or a molten liquid. The sulfur content in the vulcanized mineral oil is not particularly limited, and is usually 0.05 to 1.0% by weight based on the total amount of the vulcanized mineral oil.

The zinc dithiocarbamate compound may be a compound represented by the following general formula (17), and the molybdenum dithiocarbamate compound may be a compound represented by the following general formula (18).

[ chemical formula 13 ]

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

[ chemical formula 14 ]

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

The molybdenum dithiocarbamate compound of the general formula (18) is a 2-core complex having 2 molybdenum atoms in 1 molecule, but as the molybdenum dithiocarbamate compound, a mononuclear molybdenum complex having 1 molybdenum atom in 1 molecule or a polynuclear molybdenum complex having 3 or more molybdenum atoms in 1 molecule may be used.

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

[ 15 ] A method of producing a polypeptide

(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, R ³⁹ Represents a hydrocarbon group having 1 or more carbon atoms. )

The lubricating oil composition may or may not contain the component (E). The content of the component (E) in the lubricating oil composition is preferably 0 to 1000 mass ppm, more preferably 0 to 900 mass ppm, still more preferably 0 to 800 mass ppm, based on the total content of the composition, from the viewpoint of further improving the electrical insulation properties of the new oil and the composition after oxidation and deterioration, and is preferably 300 mass ppm or more, more preferably 400 mass ppm or more, still more preferably 500 mass ppm or more, and may be 300 to 1000 mass ppm, or 400 to 900 mass ppm, or 500 to 800 mass ppm, in one embodiment, from the viewpoint of improving the wear resistance. In the present specification, any phosphorus-containing additive should be added to the content of the component (E1), and only the additive containing sulfur having a formal oxidation number of not more than +ii but not containing phosphorus should be added to the content of the component (E2). When the component (E1) contains both phosphorus and sulfur having a formal oxidation number of not more than +II, the component (E1) is incorporated in both the content of the component (E) in terms of the phosphorus component and the content of the component (E) in terms of the sulfur component. The component (E) is a compound containing a phosphorus atom or a sulfur atom having a formal oxidation number of +II or less, but when the component (E) further contains a sulfur atom having a formal oxidation number of +III or more, the sulfur atom having any formal oxidation number in the component (E) is also included in the component (E) in terms of the sulfur component.

(F) Poly (meth) acrylate

In one embodiment, the lubricating oil composition of the present invention may further contain 1 or more polyalkyl (meth) acrylates having a weight average molecular weight of greater than 25,000 (hereinafter also referred to as "(component F"). As the component (F), 1 kind of polyalkyl (meth) acrylate may be used alone, or 2 or more kinds of polyalkyl (meth) acrylate may be used in combination. In the present specification, "meth) acrylic acid" means "acrylic acid and/or methacrylic acid".

The component (F) is a polyalkyl (meth) acrylate used as a viscosity index improver or pour point depressant in a lubricating oil, and a polymer having a weight average molecular weight of more than 25,000 can be used without particular limitation. As the component (F), either a non-dispersed poly (meth) acrylate or a dispersed poly (meth) acrylate may be used, or a combination thereof may be used, and from the viewpoint of improving the seizure resistance, a non-dispersed poly (meth) acrylate is preferably used. In the present specification, "dispersed poly (meth) acrylate" means a poly (meth) acrylate compound having a functional group containing a nitrogen atom, and "non-dispersed poly (meth) acrylate" means a poly (meth) acrylate compound having no functional group containing a nitrogen atom.

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

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

< other additives >)

In one embodiment, the lubricating oil composition may further contain a friction modifier other than the component (B) and the component (E), a viscosity index improver other than the component (F), a pour point depressant other than the component (F), an anticorrosive agent other than the component (E), an antirust agent, and 1 or more additives selected from the group consisting of a metal deactivator, an antifoaming agent, an anti-emulsifying agent, and a colorant other than the component (E).

As the friction modifier other than the component (B) and the component (E), for example, 1 or more friction modifiers selected from the group consisting of oil-soluble organic molybdenum compounds other than the component (E) and ashless friction modifiers other than the component (B) may be used. The friction modifier may be not contained in the lubricating oil composition, and the content of the friction modifier in the lubricating oil composition is preferably 0 to 2% by mass, more preferably 0 to 1% by mass, 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 deterioration. The lower limit of the content is not particularly limited, and may be 0.005% by mass or more in one embodiment.

Examples of the oil-soluble organomolybdenum compound other than the component (E) include organomolybdenum compounds containing no sulfur as a constituent element. Examples of the organic molybdenum compound containing no sulfur as a constituent element include molybdenum-amine complex, molybdenum-succinimide complex, organic acid molybdenum salt, and alcohol molybdenum salt. The organomolybdenum compound may be a mononuclear molybdenum compound, or may be a polynuclear molybdenum compound such as a binuclear molybdenum compound or a trinuclear molybdenum compound.

The lubricating oil composition may contain a metal-containing additive (for example, an organomolybdenum compound, zinc dialkyldithiophosphate, or the like) other than the metal-based detergent, or may be free from the viewpoint of further improving the electrical insulation properties of the composition after the new oil and the oxidative deterioration, and the total content of the metal elements in the lubricating oil composition is preferably less than 100 mass ppm in terms of the metal amount based on the total amount of the composition. In one embodiment, the total content of the 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, still more preferably 0 to 10 mass ppm, based on the total amount of the composition in terms of metal amount.

As the ashless friction modifier other than the component (B), a known oily agent-based friction modifier can be used without limitation. Examples of the ashless friction modifier include compounds having 6 to 50 carbon atoms, each of which contains 1 or more hetero elements selected from oxygen atoms, nitrogen atoms and sulfur atoms in the molecule. More specifically, an ashless friction modifier such as an aliphatic amine compound, an aliphatic imide compound, a fatty acid ester, a fatty acid amide, a fatty acid hydrazide, a fatty acid metal salt, an aliphatic alcohol, an aliphatic ether, or an aliphatic urea compound having at least 1 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), a known viscosity index improver used in lubricating oils can be used without limitation. Examples thereof include ethylene- α -olefin copolymers and hydrogenated products thereof, copolymers of α -olefin and ester monomer having polymerizable unsaturated bond, polyisobutylene and hydrogenated products thereof, hydrogenated products of styrene-diene copolymers, styrene-maleic anhydride ester copolymers, and polyalkylstyrenes. Among these, ethylene- α -olefin copolymers or their hydrides, or a combination thereof may be preferably used. The viscosity index improver may be either dispersed or non-dispersed. In one embodiment, the viscosity index improver can have a weight average molecular weight of, for example, 3000 to 100,000. The lubricating oil composition may or may not contain the viscosity index improver, and 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, from the viewpoint of further improving the electrical insulation properties of the composition after oxidative deterioration. The lower limit of the total content is not particularly limited, and may be 0.1 mass% or more in one embodiment.

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

The lubricating oil composition may contain a polymer component other than the component (F) (for example, a viscosity index improver or a pour point depressant), or may be free from the component, and 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%, particularly preferably 0 to 0.01 mass%, from the viewpoint of further improving the electrical insulation properties of the composition after oxidative deterioration.

As the anticorrosive agent other than the component (E), for example, known anticorrosive agents such as benzotriazole, methyltriazole, and imidazole compounds can be used. The lubricating oil composition may or may not contain an anticorrosive agent other than the component (E), and 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, from the viewpoint of further improving the electrical insulation properties of the new oil and the composition after oxidative deterioration. The lower limit of the content is not particularly limited, and may be 0.01 mass% or more in one embodiment.

As the rust inhibitor, for example, known rust inhibitors such as petroleum sulfonate, alkylbenzenesulfonate, dinonylnaphthalene sulfonate, alkenyl succinate, and polyol ester can be used. The lubricating oil composition may or may not contain a rust inhibitor, and 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, from the viewpoint of further improving the electrical insulation properties of the new oil and the composition after oxidative deterioration. The lower limit of the content is not particularly limited, and may be 0.01 mass% or more in one embodiment.

As the metal deactivator other than the component (E), for example, known metal deactivators such as imidazoline, pyrimidine derivatives, mercaptobenzothiazole, 2- (alkyldithio) benzimidazole, and β - (o-carboxybenzylthio) propionitrile can be used. The lubricating oil composition may or may not contain a metal deactivator other than the component (E), and the content of the metal deactivator 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, from the viewpoint of further improving the electrical insulation properties of the new oil and the composition after oxidative deterioration. The lower limit of the content is not particularly limited, and may be 0.01 mass% or more in one embodiment.

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

As the anti-emulsifying agent, for example, a known anti-emulsifying agent such as a polyalkylene glycol nonionic surfactant (for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl naphthalene ether, or the like) can be used. The lubricating oil composition may or may not contain an anti-emulsifying agent, and the content of the anti-emulsifying agent in the lubricating oil composition is preferably 5 mass% or less, more preferably 3 mass% or less 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 deterioration. The lower limit of the content is not particularly limited, and may be 1 mass% or more in one embodiment.

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℃is preferably 1.8mm from the viewpoint of further improving the electrical insulation properties of the new oil and the composition after oxidative deterioration and from the viewpoint of improving the wear resistance by sufficiently forming an oil film at the lubricating site ² Above/s, preferably 2.0mm ² Higher than/s, more preferably 2.2mm ² Above/s, in one embodiment 2.3mm ² In addition, from the viewpoint of improving fuel economy, it is preferably 4.0mm or more ² Preferably less than/s, 3.8mm ² And/s or less, in one embodiment may be 1.8 to 4.0mm ² /s, or 2.0-4.0 mm ² /s, or 2.2-4.0 mm ² /s, or 2.3-3.8 mm ² /s。

The kinematic viscosity of the lubricating oil composition at 40℃is preferably 6.8mm from the viewpoints of electrical insulation properties of the new oil and the composition after oxidative deterioration and further improvement of wear resistance ² Higher than/s, more preferably 7.2mm ² Above/s, in one embodiment 8.0mm ² In addition, from the viewpoint of further improving fuel economy, it is preferably 14.5mm or more ² Is less than/s,More preferably 13.7mm ² Less than/s, in one embodiment 13.0mm ² And/s or less, in one embodiment may be 6.8 to 14.5mm ² /s, or 7.2-13.7 mm ² /s, or 8.0-13.0 mm ² /s。

From the viewpoint of improving energy saving, the lower the kinematic viscosity of the lubricating oil composition is, the better. However, in general, when an additive is added to the base oil ((O) component), the kinematic viscosity of the entire lubricating oil composition increases. This means that the limit point for improving the energy saving performance by lowering the viscosity of the lubricating oil is determined based on the kinematic viscosity of the total base oil ((O) component). Therefore, from the viewpoint of improving energy saving, the lower the kinematic viscosity of the total base oil is, the better. On the other hand, from the viewpoints of abrasion resistance, oxidation stability, and electrical insulation of the new oil and the composition after oxidation deterioration, the kinematic viscosity of the total base oil is preferably at a level of not less than a certain level. Under the constraint of keeping the kinematic viscosity of the total base oil at a predetermined level or more, the viscosity-increasing effect of the additive is a hindrance to the reduction of the viscosity of the lubricating oil. From the viewpoint of further improving energy saving, the kinematic viscosity KV at 40 ℃ of the lubricating oil composition ₄₀ ^Comp And kinematic viscosity KV at 40 ℃ of total base oil ((O) component) ₄₀ ^BO Difference (KV) ₄₀ ^Comp -KV ₄₀ ^BO ) I.e. the additive preferably has a tackifying effect of 2.5mm ² Less than/s, in one embodiment 2.4mm ² In addition, from the viewpoint of further improving the durability against oxidative deterioration, it is preferably 1.0mm or less ² Higher than/s, more preferably 1.5mm ² Above/s, in one embodiment 1.8mm ² And/s or more, in one embodiment may be 1.0 to 2.5mm ² /s, or 1.5-2.5 mm ² /s, or 1.8-2.4 mm ² /s。

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

In one embodiment, the new lubricating oil compositionsThe volume resistivity of the oil at 80℃is preferably 0.21X 10 ¹⁰ Omega cm or more. The upper limit of the volume resistivity of the new oil at 80℃is not particularly limited, and in one embodiment the volume resistivity may be 0.21X 10 ¹⁰ ～0.60×10 ¹⁰ Omega cm, or 0.21X10 ¹⁰ ～0.45×10 ¹⁰ Omega cm. In the present specification, the volume resistivity of the new oil is measured at an oil temperature of 80 ℃ based on the volume resistivity test specified in JIS C2101.

In one embodiment, the volume resistivity at 80℃as measured on an oxidatively altered oil of the lubricating oil composition is preferably 0.10X10 ¹⁰ Omega cm or more. The upper limit of the volume resistivity of the oxidized modified oil at 80℃is not particularly limited, and in one embodiment the volume resistivity may be 0.10X10 ¹⁰ ～0.40×10 ¹⁰ Omega cm, or 0.10X10 ¹⁰ ～0.25×10 ¹⁰ Omega cm. In the present specification, the volume resistivity of the oxidized and denatured oil is measured at an oil temperature of 80 ℃ based on a volume resistivity test defined in JIS C2101 by oxidizing a fresh oil according to the ISOT method (Indiana Stirring Oxidation Test) defined in JIS K2514-1 at 165 ℃ for 150 hours to obtain an oxidized and denatured oil.

In one embodiment, the metal-based detergent (e.g., a metal salicylic acid detergent such as component (C), a metal sulfonic acid detergent, a metal phenate detergent, etc.), the phosphorous acid diester compound having no O/N-based active hydrogen-containing group at the alcohol residue (e.g., a phosphite compound represented by the general formula (8) (component E1), etc.), the 1 st succinimide compound (component A), the 2 nd succinimide compound (component B), an amine-based antioxidant or a phenol-based antioxidant (component D), and a poly (meth) acrylate (e.g., component F), etc.), or a salt thereof, > NH group, or-NH group thereof are not included in the content of any of the components (e.g., the metal salicylic acid detergent, the metal sulfonic acid detergent, the metal phenate detergent, etc.), the phosphorous acid diester compound having no O/N-based active hydrogen-containing group at the alcohol residue (e.g., a part of other functional groups (e.g., carboxyl group, phosphate group, etc.) ₂ The total content of the compounds (hereinafter referred to as "O/N-based active hydrogen-containing groups") having a group (hereinafter referred to as "O/N-based active hydrogen-containing groups") is based on the total composition from the viewpoint of further improving the electrical insulation properties of the novel oil and the composition after oxidative deteriorationThe amount is preferably 0 to 500 mass ppm, in one embodiment 0 to 300 mass ppm, and in one other embodiment 0 to 150 mass ppm, based on the total amount of the oxygen element and the nitrogen element. Examples of such O/N-based 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 having no O/N active hydrogen-containing groups on the alcohol residue do not belong to O/N active hydrogen compounds); nitrogen-containing oily agent-based friction modifiers having an N-H bond (for example, primary aliphatic amine, secondary aliphatic amine, primary aliphatic amide, secondary aliphatic amide, aliphatic urea having an N-H bond, and aliphatic hydrazide); nitrogen-containing oily agent having a hydroxyl group is a friction modifier (for example, an amide formed from a fatty acid and a primary or secondary alkanolamine, an amide formed from an aliphatic primary or secondary amine and an aliphatic hydroxy acid, etc.); a nitrogen-containing oily agent-based friction modifier having a carboxyl group (which can form a salt) (for example, an N-acylated amino acid or the like); an oily agent-based friction modifier having a hydroxyl group (for example, glycerol monooleate); and an oily agent-based friction modifier (for example, fatty acid metal salt, etc.) having a carboxyl group (salt-forming group). When one O/N-based active hydrogen compound contains both an oxygen element and a nitrogen element, both the amount of the oxygen element and the amount of the nitrogen element derived from the compound account for the total content of the O/N-based active hydrogen compound (the total amount of the oxygen element and the nitrogen element) described above, irrespective of whether or not each oxygen atom of the compound is bonded to a hydrogen atom and whether or not each nitrogen atom of the compound is bonded to a hydrogen atom.

(use)

The lubricating oil composition of the present invention has low viscosity and electrical insulation required for lubricating an electric engine, and thus alleviates problems caused by oxidation and deterioration in lubrication of an automatic transmission and in lubrication of an electric engine, and can be preferably used for lubrication of an automatic transmission as a lubricating oil having improved fuel efficiency, and can be preferably used for lubrication and cooling of an electric engine as a lubricating oil having improved energy saving. Further, by using the lubricating oil composition of the present invention, both an automatic transmission and an electric engine can be lubricated. Such a lubricating method may comprise, for example, supplying the lubricating oil composition of the present invention to an automatic transmission of an automobile having an automatic transmission and an electric engine, and supplying the lubricating oil composition to the electric engine of the automobile.

[ example ]

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, 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, lubricating oil compositions of the present invention (examples 1 to 20) and lubricating oil compositions for comparison (comparative examples 1 to 8) were prepared, respectively. In the table, "mass%" in the item of "base oil composition" means mass% based on the total amount of base oil (100 mass%), and "mass%" in the other items means mass% based on the total amount of lubricating oil composition (100 mass%). The term "mass ppm" means mass ppm based on the total amount of the lubricating oil composition, and the expression of "mass ppm/X" of the element X means mass ppm based on the total amount of the composition as the amount of the element X. Details of the respective components are as follows.

((O) lubricating base oils)

O-1: API group III base oils (hydrocracked mineral oil base oils), kinematic viscosity (40 ℃): 7.0mm ² /s, kinematic viscosity (100 ℃). 2.2mm ² S, viscosity index: 121. saturation: 99.6, sulfur component: less than 1 mass ppm,% C _P ：77.4、％C _N ：22.0、％C _A ：0.6

O-2: API group III base oils (hydrocracked mineral oil base oils), kinematic viscosity (40 ℃): 19.2mm ² /s, kinematic viscosity (100 ℃). 4.2mm ² S, viscosity index: 124. saturation: 99.7, sulfur component: less than 1 mass ppm,% C _P ：79.4、％C _N ：20.6、％C _A ：0.0

O-3: API group III base oils (hydrocracked mineral oil base oils), kinematic viscosity (40 ℃): 18.2mm ² /s, kinematic viscosity (100 ℃). 4.2mm ² S, viscosity index: 135. saturation: 99.8, sulfur component: less than 1 mass ppm,% C _P ：86.6、％C _N ：13.4、％C _A ：0.0

O-4: API group III base oils (wax isomerized mineral oil base oils), kinematic viscosity (40 ℃): 9.2mm ² /s, kinematic viscosity (100 ℃). 2.6mm ² S, viscosity index: 126. saturation: 99.8, sulfur component: less than 1 mass ppm,% C _P ：91.8、％C _N ：8.2、％C _A ：0.0

O-5: API group IV base oils, kinematic viscosity (40 ℃): 18.4mm ² /s, kinematic viscosity (100 ℃). 4.1mm ² S, viscosity index: 124

O-6: API group V base oils (2-ethylhexyl oleate), kinematic viscosity (40 ℃ C.): 8.2mm ² /s, kinematic viscosity (100 ℃). 2.7mm ² S, viscosity index: 186

((A) 1 st succinimide compound)

A-1: condensation reaction product of polyisobutenyl succinic anhydride with polyamine (non-modified polyisobutenyl succinimide dispersant), weight average molecular weight: 5200. n:1.3 mass%, number average molecular weight of polyisobutenyl: 1600

A-2: boric acid modification of 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: 2500

((B) 2 nd succinimide compound)

B-1: condensation reaction product of octadecenyl succinic anhydride with polyamine, N:5.3 mass%

((C) Metal-based detergent)

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

((D) antioxidant)

D-1: amine antioxidant (alkylated diphenylamine)

D-2: phenolic antioxidants (octyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) acrylate)

((E) phosphorus/Sulfur additives)

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

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

[ Table 1 ]

[ Table 2 ]

[ Table 3 ]

[ Table 4 ]

[ Table 5 ]

[ Table 6 ]

(thickening by additives)

For each lubricating oil composition, the Kinematic Viscosity (KV) of the composition at 40 ℃ was calculated ₄₀ ^Comp ) Kinematic viscosity at 40℃relative to the total base oil ((O) component) (KV) ₄₀ ^BO ) Increment (KV) ₄₀ ^Comp -KV ₄₀ ^BO ) The viscosity increase caused by the additives was evaluated. The results are shown in tables 1 to 6. The smaller the value, the smaller the reduction in energy saving property caused by the tackifying effect of the additive. The increase in kinematic viscosity at 40℃caused by the additives is preferably 2.5mm ² And/s or less.

(ISOT oxidation test)

The oxidation-modified oil was obtained by subjecting the fresh oil to oxidation treatment at 165℃for 150 hours at the oil temperature, based on the method ISOT (Indiana Stirring Oxidation Test) in JIS K2514-1, for each lubricating oil composition. The acid value of the new oil and the oxidized and modified oil was measured by a potentiometric titration method based on JIS K2501-2003, and the increase in acid value after the oxidation and modification was evaluated. The results are shown in tables 1 to 6. The smaller the increase in acid value in this test, the better the durability against oxidative deterioration. The increase in acid value in this test is preferably 1.5mgKOH/g or less.

(volume resistivity)

For each lubricating oil composition, the volume resistivity of the fresh oil and the volume resistivity of the oxidized and altered oil obtained by the above-mentioned ISOT oxidation test were measured. For each new oil and oxidation change The volume resistivity of the oil was measured by the volume resistivity test defined in JIS C2101 at an oil temperature of 80 ℃. 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 novel oils in this test at 80℃is preferably 0.21X 10 ¹⁰ Omega cm or more. In addition, in the present test, the volume resistivity of the oxidized modified oil at 80℃is preferably 0.10X10 ¹⁰ Omega cm or more.

(evaluation results)

The lubricating oil compositions of examples 1 to 20 were low in viscosity and had a low viscosity, and the acid value of the oxidation-modified oil was increased, and the electrical insulation properties of the new oil and the electrical insulation properties of the composition after oxidation-modification were excellent.

(A) The lubricating oil composition of comparative example 1, in which the content (mass ppm) of the component in terms of nitrogen component was too small, had an increased acid value of the oxidized and denatured oil and had poor electrical insulation properties of the composition after the oxidation and denaturation.

(A) The lubricating oil composition of comparative example 2, in which the content (mass%) of the components based on the total compound was excessively large, was poor in electrical insulation properties of the composition after oxidative deterioration.

(A) 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) in the total amount of the compound was excessively large, had a large increase in viscosity due to the additive, and was poor in energy saving property.

(A) The lubricating oil composition of comparative example 4, in which the product of the weight average molecular weight of the component (a) and the content (mass%) of the component (a) in the total amount of the compound were too large, was poor in the electrical insulation properties of the new oil, in addition to the large increase in viscosity due to the additives, and was poor in the energy saving properties.

In the lubricating oil composition of comparative example 5 containing no component (B), the acid value of the oxidation-modified oil was poor.

(B) The lubricating oil composition of comparative example 6 having too large a content of components was poor in electrical insulation properties after oxidative deterioration.

The lubricating oil composition of comparative example 7, which did not contain the component (B) and instead contained the component (C), namely, the metal-based detergent, in an amount to reduce the increase in acid value of the oxidation-modified oil, was poor in electrical insulation properties of the fresh oil and the oxidation-modified oil.

The lubricating oil composition of comparative example 8, in which the content of component (a) was increased to reduce the increase in acid value of the oxidation-modified oil while reducing the content of component (C) in the composition of comparative example 7, was poor in energy saving property as well as in which the viscosity increase by the additive was large in addition to the electrical insulation property of the new oil.

Claims

1. A lubricating oil composition comprising

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.