JPWO2019177125A1 - Lubricating oil composition - Google Patents

Abstract

Base oil (A), ashless dispersant (B) containing non-boronized alkenyl succinate imide (B1) and boronized alkenyl succinate imide (B2), thiadiazole compound (C), and one or more hydroxyl groups A lubricating oil composition containing the aromatic carboxylic acid ester (D) having the above, wherein the content of the component (C) is 0.2 to 1.2% by mass based on the total amount of the lubricating oil composition. Yes, the content of zinc dithiophosphate in terms of zinc atom is less than 500 mass ppm based on the total amount of the lubricating oil composition, and the content of the metal-based cleaning agent in terms of metal atom is the content of the lubricating oil composition. A lubricating oil composition used in an internal combustion engine, which is less than 600 mass ppm based on the total amount of the compound.

Description

The present invention relates to a lubricating oil composition.

In recent years, automobile engines have been required to have higher engine output and stricter exhaust gas regulations, and exhaust gas aftertreatment devices are being developed.
An oxidation catalyst, a three-way catalyst, a DPF (diesel particulate filter), or the like is adopted in such an exhaust gas aftertreatment device in order to purify the exhaust gas.
However, the phosphorus content in the engine oil poisons the active site of the catalyst and reduces the catalytic function, and the ash content derived from the metal content accumulates on the DPF, which causes the life to be shortened. Has been reported. In addition, metal-derived ash is also a factor that accumulates on the upper part of the piston and accelerates the contamination of spark spark plugs.
Therefore, there is a tendency to demand an automobile engine oil in which the amount of phosphorus-containing wear resistant agent and metal-based additive, which has been conventionally used, is reduced.

There is also a demand for gas engine oils in which the blending amount of these additives is reduced and the phosphorus content and sulfated ash content are reduced.
The gas engine uses natural gas, liquefied petroleum gas (LPG), auto gas, etc. as fuel, has good combustibility, and has a higher combustion temperature than a gasoline engine or a diesel engine. Therefore, since the engine oil used for a gas engine is used under a high load condition, deterioration is likely to be promoted, and a problem is likely to occur in terms of life.
Further, in a gas engine operated under a high load condition, various additives in the engine oil used are easily decomposed, and the decomposition products of the additives are corroded by copper contained in the members constituting the engine. It is easy to cause it to occur.
Therefore, engine oils used in gas engines are required to have metal corrosion resistance as well as deterioration suppression, and various engine oils are being developed.

For example, Patent Document 1 describes a base oil and HLB for the purpose of providing an engine oil composition for a gas engine, which has excellent metal corrosion prevention properties such as copper corrosion prevention properties for gas engine bearing members and has a long life. An engine oil composition containing a predetermined amount of a polyoxyethylene alkyl ether having a value of 8 to 11 and an organic molybdenum complex is disclosed.

JP-A-2010-209182

By the way, in recent years, automobile engines and gas engines have been increasing in output year by year. In high-power automobile engines and gas engines, bearings such as piston pins and sliding parts become hot, so the engine oil that lubricates the members has a higher temperature of over 160 ° C, which is higher than before. It is required to maintain various performances when used in an environment. In a high temperature environment of more than 160 ° C., oxidative deterioration of engine oil is more likely to occur, and a decrease in heat resistance becomes a bigger problem.
It is also conceivable to add a metal-based cleaning agent to the engine oil to suppress oxidative deterioration. However, according to the studies by the present inventors, it has been found that the formulation of a metal-based cleaning agent may cause a decrease in wear resistance.

Further, metal parts constituting bearings and sliding parts such as piston pins included in high-power automobile engines and gas engines are more likely to be corroded in a high temperature environment of more than 160 ° C.
In particular, when zinc dithiophosphate (ZnDTP) is contained as an abrasion resistant agent in the engine oil, the decomposition of zinc dithiophosphate is further promoted in such a high temperature environment of more than 160 ° C. Phosphoric acid is likely to be generated, which is a factor that promotes corrosion of metal parts.

Although Patent Document 1 also studies the metal corrosion resistance of engine oil, its temperature is 135 ° C., and it has been studied assuming use in such a high temperature environment of over 160 ° C. Absent.
Further, according to the study of the present inventions, it was found that the engine oil disclosed as a specific example in Patent Document 1 has a problem in metal corrosion resistance in a high temperature environment of more than 160 ° C.

In addition, as described above, automobile engines and gas engines have been increased in output, and engines are being supercharged. Attempts have been made to use laser spark plugs in internal combustion engines because they are easier to ignite under high pressure than conventional spark plugs. However, metal-derived ash can be a factor in accelerating contamination not only for conventional spark plugs but also for laser spark plugs.

The present invention has been made in view of the above problems, has excellent wear resistance, and exhibits excellent metal corrosion resistance and heat resistance even when used in a high temperature environment of more than 160 ° C. It is an object of the present invention to provide a lubricating oil composition which can be used.

The present inventors contain an ashless dispersant containing a non-boronized alkenyl succinate imide and a boronized alkenyl succinate imide, a thiadiazole-based compound, and an aromatic carboxylic acid ester having one or more hydroxyl groups. We have found that a lubricating oil composition in which the content of a thiadiazole-based compound is within a predetermined range and the content of each of zinc dithiophosphate and a metal-based cleaning agent is adjusted to a predetermined value or less can solve the above problems, and the present invention has been found. Was completed.

That is, the present invention provides the following [1].
[1] Base oil (A),
An ashless dispersant (B) containing a non-borated alkenyl succinate imide (B1) and a boborated alkenyl succinate imide (B2),
Thiadiazole compound (C) and aromatic carboxylic acid ester (D) having 1 or more hydroxyl groups
A lubricating oil composition containing
The content of the component (C) is 0.2 to 1.2% by mass based on the total amount of the lubricating oil composition.
The content of zinc dithiophosphate in terms of zinc atoms is less than 500 mass ppm based on the total amount of the lubricating oil composition.
The content of the metal-based cleaning agent in terms of metal atoms is less than 600 mass ppm based on the total amount of the lubricating oil composition.
Lubricating oil composition used for internal combustion engines.

The lubricating oil composition of the present invention has excellent wear resistance and can exhibit excellent metal corrosion resistance and heat resistance even when used in a high temperature environment of more than 160 ° C.

In the present specification, the contents of boron atom, phosphorus atom, calcium atom, zinc atom, and molybdenum atom mean a value measured according to JPI-5S-38-03.
Further, the content of nitrogen atom means a value measured in accordance with JIS K2609: 1998.
Further, the content of sulfur atom means a value measured according to JIS K2541-6: 2013.

[Lubricating oil composition]
The lubricating oil composition of the present invention comprises a base oil (A), an ashless dispersant (B) containing a non-boronized alkenyl succinate imide (B1) and a boring alkenyl succinate imide (B2), and a thiazizol compound. It contains (C) and an aromatic carboxylic acid ester (D) having one or more hydroxyl groups, and is used in an internal combustion engine.
In the present specification, the base oil (A), the ashless dispersant (B), the thiadiazole compound (C), and the aromatic carboxylic acid ester (D) having one or more hydroxyl groups are each referred to as "component (A)". , "Component (B)", "Component (C)", and "Component (D)".
Further, the non-borated alkenyl succinate imide (B1) and the borated alkenyl succinate imide (B2) are also referred to as "component (B1)" and "component (B2)", respectively.

The lubricating oil composition of one aspect of the present invention may contain other additives for lubricating oil that do not correspond to the above components as long as the effects of the present invention are not impaired.

In the lubricating oil composition of one aspect of the present invention, the total content of the component (A), the component (B), the component (C), and the component (D) is the total amount (100% by mass) of the lubricating oil composition. By reference, it is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 75% by mass or more, still more preferably 80% by mass or more, and usually 100% by mass or less, preferably 99.5% by mass. It is 99.0% by mass or less, more preferably 99.0% by mass or less.
Hereinafter, each component contained in the lubricating oil composition of one aspect of the present invention will be described.

<Base oil (A)>
The base oil (A) contained in the lubricating oil composition of the present invention may contain at least one selected from mineral oils and synthetic oils.

As the mineral oil, for example, atmospheric residual oil obtained by atmospheric distillation of crude oil such as paraffin crude oil, intermediate base crude oil, and naphthen crude oil; and distillate obtained by vacuum distillation of these atmospheric residual oils. Mineral oil obtained by subjecting the distillate oil to one or more purification treatments such as solvent removal, solvent extraction, hydrocracking, solvent removal, catalytic removal, hydrorefining, etc .; Fisher-Tropsch method from natural gas Examples thereof include mineral oil (GTL) obtained by isomerizing a wax (GTL wax (Gas To Liquids WAX)) produced by the above.
As the mineral oil used in one aspect of the present invention, mineral oils classified into Group 2 or 3 of the base oil category of API (American Petroleum Institute) are preferable, and mineral oils classified into Group 3 are more preferable.

Examples of the synthetic oil include poly such as an α-olefin homopolymer or an α-olefin copolymer (for example, an α-olefin copolymer having 8 to 14 carbon atoms such as an ethylene-α-olefin copolymer). Examples thereof include α-olefins; isoparaffins; various esters such as polyol esters and dibasic acid esters; various ethers such as polyphenyl ethers; polyalkylene glycols; alkylbenzenes; synthetic oils such as alkylnaphthalene.

The kinematic viscosity at 40 ° C. of the base oil (A), preferably 10 to 150 mm ² / s, more preferably 12~120mm ² / s, more preferably 15~100mm ² / s.

The viscosity index of the base oil (A) is preferably 80 or more, more preferably 90 or more, still more preferably 100 or more, still more preferably 105 or more.

In this specification, the kinematic viscosity and the viscosity index mean values measured or calculated in accordance with JIS K 2283: 2000.
When the base oil (A) is two or more kinds of mixed base oils selected from mineral oils and synthetic oils, the kinematic viscosity and viscosity index of the mixed base oils may be within the above ranges.

In the lubricating oil composition of one aspect of the present invention, the content of the base oil (A) is usually 55% by mass or more, preferably 60% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition. It is more preferably 65% by mass or more, further preferably 70% by mass or more, still more preferably 75% by mass or more, and preferably 98% by mass or less, more preferably 97% by mass or less, still more preferably 95% by mass. Hereinafter, it is even more preferably 93% by mass or less.

<Ashes-free dispersant (B)>
The lubricating oil composition of the present invention contains an ashless dispersant (B) containing a non-borated alkenyl succinate imide (B1) and a borated alkenyl succinate imide (B2).
By using the component (B1) and the component (B2) in combination, the dispersibility of the components (C) and (D) is improved, and excellent metal corrosion resistance is obtained even when used in a high temperature environment of more than 160 ° C. And can be a lubricating oil composition capable of exhibiting heat resistance.

From the above viewpoint, the content ratio [B / N] of the boron atom and the nitrogen atom of the component (B) is preferably 0.10 to 1.30, more preferably 0.20 to 1. 20, more preferably 0.25 to 1.10, even more preferably 0.30 to 1.10, and even more preferably 0.70 to 1.05.

The content ratio of the component (B1) to the component (B2) [(B1) / (B2)] is preferably 0.01 to 6.00, more preferably 0.05 to 4. It is 00, more preferably 0.10 to 2.00, even more preferably 0.15 to 1.50, and even more preferably 0.25 to 0.95.

(Nonborated alkenyl succinate imide (B1))
Examples of the non-borated alkenyl succinate imide (B1) include alkenyl succinate monoimide represented by the following general formula (b-1) and alkenyl succinate bisimide represented by the following general formula (b-2). ..

The general formula (b-1), (b -2) ^in, R ^{A, R A1} and ^{R A2} are each independently a number average molecular weight (Mn) of 500 to 3000 (preferably 1000 to 3000, more preferably It is an alkenyl group of 1500-2500).
Examples of the alkenyl group include a polybutenyl group, a polyisobutenyl group, an ethylene-propylene copolymer and the like, and among these, a polybutenyl group or a polyisobutenyl group is preferable.

R ^{B, R B1} and ^{R B2} are each independently an alkylene group having 2 to 5 carbon atoms.
^RC is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or _{a group represented by − (AO) n} −H (where A is an alkylene group having 2 to 4 carbon atoms and n is an integer of 1 to 10 carbon atoms. Is shown.).
x1 is an integer of 1 to 10, preferably an integer of 2 to 5, and more preferably 3 or 4.
x2 is an integer of 0 to 10, preferably an integer of 1 to 4, more preferably 2 or 3.

The component (B1) can be produced, for example, by reacting an alkenyl succinic anhydride obtained by reacting a polyolefin with maleic anhydride with a polyamine.
Examples of the polyolefin include a polymer obtained by polymerizing one or more selected from α-olefins having 2 to 8 carbon atoms, and a copolymer of isobutene and 1-butene is preferable.
Examples of the polyamines include single diamines such as ethylenediamine, propylenediamine, butylenediamine and pentylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di (methylethylene) triamine and dibutylene. Polyalkylene polyamines such as triamine, tributylenetetramine, and pentapentylene hexamine; piperazine derivatives such as aminoethylpiperazine; and the like.

The component (B1) used in one embodiment of the present invention includes the compounds represented by the general formulas (b-1) and (b-2), alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, and organic compounds. It may be a modified alkenyl succinate imide obtained by reacting with a non-boron-containing compound such as an acid.

In the lubricating oil composition of one aspect of the present invention, the content of the component (B1) in terms of nitrogen atom is preferably 400 to 3000 mass ppm based on the total amount (100% by mass) of the lubricating oil composition. It is preferably 420 to 2500 mass ppm, more preferably 450 to 2200 mass ppm, even more preferably 480 to 2000 mass ppm, and even more preferably 500 to 1500 mass ppm.

In the lubricating oil composition of one aspect of the present invention, the content of the component (B1) may be adjusted so that the content in terms of nitrogen atoms is within the above range, but the total amount of the lubricating oil composition. On the basis of (100% by mass), it is preferably 0.1 to 8.0% by mass, more preferably 0.2 to 6.0% by mass, and further preferably 0.3 to 4.0% by mass.

(Imide borated alkenyl succinate (B2))
Examples of the boronized alkenyl succinate imide (B2) include boron-modified alkenyl succinate imide represented by the following general formula (b-1) or (b-2).
The boronized alkenyl succinate imide (B2) can be produced, for example, by reacting the alkenyl succinic anhydride obtained by the reaction of the above-mentioned polyolefin with maleic anhydride with the above-mentioned polyamine and boron compound.
Examples of the boron compound include boron oxide, boron halide, boric acid, boric anhydride, boric acid ester, and ammonium salt of boric acid.

The content ratio [B / N] of the boron atom and the nitrogen atom in the component (B2) used in one aspect of the present invention is preferably 0.3 to 2.5, more preferably 0.5 in terms of mass ratio. It is ~ 2.0, more preferably 0.7 ~ 1.5.

In the lubricating oil composition of one aspect of the present invention, the content of the component (B2) in terms of boron atom is preferably 200 to 3000 mass ppm based on the total amount (100% by mass) of the lubricating oil composition. It is preferably 400 to 2800 mass ppm, more preferably 600 to 2700 mass ppm, even more preferably 700 to 2600 mass ppm, and even more preferably 1100 to 2500 mass ppm.

Further, in the lubricating oil composition of one aspect of the present invention, the content of the component (B2) in terms of nitrogen atom is preferably 250 to 3500 mass ppm based on the total amount (100 mass%) of the lubricating oil composition. , More preferably 300 to 3200 mass ppm, still more preferably 350 to 2800 mass ppm, and even more preferably 400 to 2500 mass ppm.

In the lubricating oil composition of one aspect of the present invention, the content of the component (B2) may be adjusted so that the content in terms of boron atom and nitrogen atom is within the above range. Based on the total amount (100% by mass) of the composition, preferably 0.1 to 15.0% by mass, more preferably 0.5 to 13.0% by mass, still more preferably 1.0 to 11.0% by mass. is there.

The lubricating oil composition according to one aspect of the present invention contains an ashless dispersant other than the components (B1) and (B2) as the component (B) as long as the effects of the present invention are not impaired. You may.
Examples of the ashless dispersant include benzylamines, boron-containing benzylamines, succinic acid esters, fatty acids, monovalent or divalent carboxylic acid amides typified by succinic acid, and the like.

However, in the lubricating oil composition of one aspect of the present invention, the total content ratio of the components (B1) and (B2) in the ashless dispersant (B) is the ashless type contained in the lubricating oil composition. With respect to the total amount (100% by mass) of the dispersant (B), preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass. %.

Further, in the lubricating oil composition of one aspect of the present invention, the content of the component (B) in terms of nitrogen atom is preferably 600 to 6500 mass ppm based on the total amount (100 mass%) of the lubricating oil composition. , More preferably 700 to 5200 mass ppm, still more preferably 800 to 4000 mass ppm, and even more preferably 850 to 3500 mass ppm.

In the lubricating oil composition of one aspect of the present invention, the content of the component (B) is preferably 0.2 to 30.0% by mass, more preferably 0.2 to 30.0% by mass, based on the total amount (100% by mass) of the lubricating oil composition. Is 0.7 to 27% by mass, more preferably 1.5 to 25.0% by mass, and even more preferably 3.0 to 15.0% by mass.

<Thiadiazole compound (C)>
The lubricating oil composition of the present invention contains a thiadiazole compound (C), and the content of the component (C) is 0.2 to 1.2% by mass based on the total amount (100% by mass) of the lubricating oil composition. %.
A lubricating oil composition having a content of the component (C) of less than 0.2% by mass is difficult to exhibit a friction reducing effect, and has a problem in terms of wear resistance.
On the other hand, a lubricating oil composition having a component (C) content of more than 1.2% by mass tends to cause corrosion of metal parts when used in a high temperature environment of more than 160 ° C., and is resistant to metal corrosion. There is a problem in that. In addition, when used in the same environment, oxidative deterioration is likely to occur, and there is a problem in terms of heat resistance.

In the lubricating oil composition of one aspect of the present invention, the content of the component (C) is preferably 0.22 from the viewpoint of improving wear resistance based on the total amount (100% by mass) of the lubricating oil composition. By mass% or more, more preferably 0.25% by mass or more, still more preferably 0.30% by mass or more, still more preferably 0.35% by mass or more, still more preferably 0.40% by mass or more, and further. From the viewpoint of improving metal corrosion resistance and heat resistance, it is preferably 1.15% by mass or less, more preferably 1.10% by mass or less, still more preferably 1.00% by mass or less, still more preferably 0.90% by mass. % Or less.

Further, in the lubricating oil composition of one aspect of the present invention, the content of the component (C) in terms of sulfur atom is based on the total amount (100% by mass) of the lubricating oil composition, and the wear resistance is improved. From the viewpoint, it is preferably 500 mass ppm or more, more preferably 700 mass ppm or more, further preferably 900 mass ppm or more, still more preferably 1200 mass ppm or more, and also from the viewpoint of improving metal corrosion resistance and heat resistance. Therefore, it is preferably 4000 mass ppm or less, more preferably 3800 mass ppm or less, still more preferably 3600 mass ppm or less, still more preferably 3000 mass ppm or less.

The thiadiazole-based compound (C) used in one embodiment of the present invention may be a compound having a thiadiazole ring, but from the viewpoint of providing a lubricating oil composition having excellent wear resistance, the 1,3,4-thiadiazole ring It is preferable that the compound has the above, and more preferably the compound represented by the following general formula (c-1).
The component (C) may be used alone or in combination of two or more.

In the general formula (c-1), p and q are independently integers of 0 to 5 (preferably integers of 1 to 5, more preferably 1 or 2, still more preferably 2), and p + q is 1 or more.
In one aspect of the present invention, it is preferable that p = q.
On the other hand, r and s are independently integers of 1 to 5 (preferably 1 or 2, more preferably 1).

R ^a and R ^b are heteroatom-containing groups each independently containing one or more hydrogen atoms, hydrocarbon groups, or oxygen atoms, nitrogen atoms, and sulfur atoms, but they must be hydrocarbon groups. Is preferable.

^{Examples of the hydrocarbon group that can be selected as Ra} and R ^b include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group and a 1,1-dimethylhexyl group. , 2-ethylhexyl group, nonyl group, 1,1-dimethylheptyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and other linear or branched chains. Alkyl group of: octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group and other linear or branched alkenyl groups; cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group , Cycloalkyl groups such as dimethylcyclohexyl group, ethylcyclohexyl group, methylcyclohexylmethyl group, cyclohexylethyl group, propylcyclohexyl group, butylcyclohexyl group, heptylcyclohexyl group; phenyl group, naphthyl group, anthracenyl group, biphenyl group, terphenyl group Oryl groups such as: trill group, dimethylphenyl group, butylphenyl group, nonylphenyl group, methylbenzyl group, dimethylnaphthyl group and other alkylaryl groups; phenylmethyl group, phenylethyl group, diphenylmethyl group and other arylalkyl groups and the like. Can be mentioned.
Among these, the hydrocarbon group that can be selected as ^Ra and R ^{b is preferably an alkyl group.} The alkyl group may be a straight chain alkyl group or a branched chain alkyl group.

The number of carbon atoms in the hydrocarbon is preferably 1 to 30, more preferably 1 to 24, still more preferably 4 to 16, and even more preferably 6 to 12.

Examples of the hetero atom-containing group that can be selected as R ^a and R ^b include a hydroxyl group, an amino group, a nitro group, a carboxyl group, a sulfo group, and a group represented by −COOR (R is the above-mentioned hydrocarbon). Groups) and hydrocarbon groups substituted with these groups and the like.
Among these, as the hetero atom-containing group, an alkyl group having 1 to 30 carbon atoms substituted with a hydroxyl group or a group represented by −COOR (R is the above-mentioned hydrocarbon group, but is preferable. Is an alkyl group having 1 to 30 carbon atoms).

As the component (C) used in one embodiment of the present invention, p and q in the general formula (c-1) are independently 1 or 2, r and s are 1, and ^Ra and R are used. ^A compound in which b is an alkyl group having a linear or branched chain having 1 to 30 carbon atoms is preferable, and a compound represented by the following general formula (c-11) is more preferable, and the following general formula (c-11) is more preferable. The compound represented by c-12) is more preferable.

In the general formula (c-11), R ^a1 and R ^b1 are independently linear or branched alkyl groups having 1 to 30 carbon atoms, but are branched chain alkyl groups having 4 to 16 carbon atoms. It is preferably a branched-chain alkyl group having 6 to 12 carbon atoms, and more preferably.

Further, in the general formula (c-12), Ra ² and R ^{b 2} are independently linear or branched alkyl groups having 1 to 16 carbon atoms, but are linear alkyl groups having 1 to 16 carbon atoms. It is more preferably a group, and even more preferably a straight chain alkyl group having 4 to 12 carbon atoms.
R ^c , R ^d , ^Re and R ^f are independently hydrogen atoms or alkyl groups having 1 to 6 carbon atoms, and ^{at least one of R c} and R ^d , and at least one of R ^e and R ^f . Is an alkyl group having 1 to 6 carbon atoms.
However, R ^c , R ^d , ^Re and R ^f are each independently preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group, and are a methyl group. Is even more preferable.

<Aromatic carboxylic acid ester (D) having 1 or more hydroxyl groups>
The lubricating oil composition of the present invention contains an aromatic carboxylic acid ester (D) having one or more hydroxyl groups.
The component (D) may be used alone or in combination of two or more.
Since the lubricating oil composition of the present invention contains the component (D), it can exhibit excellent heat resistance even when used in a high temperature environment of more than 160 ° C.

In particular, in the lubricating oil composition of the present invention, the presence of the component (B2) makes it easy for the component (D) to disperse, and the performance of the component (D) can be exhibited more remarkably, so that the temperature is higher than 160 ° C. It has excellent heat resistance even when used in an environment.

From the above viewpoint, in the lubricating oil composition of one aspect of the present invention, the content ratio [(D) / (B2)] of the component (D) to the component (B2) is preferably 0.1 in terms of mass ratio. ~ 5.0, more preferably 0.15 to 4.0, still more preferably 0.2 to 3.0, even more preferably 0.3 to 2.0.

Examples of the aromatic carboxylic acid ester (D) having one or more hydroxyl groups used in one embodiment of the present invention include the compound (D1) represented by the following general formula (d-1) and the following general formula (d-2). ) Is preferably one or more selected from the compound (D2), and more preferably at least the compound (D1) is contained.

In the general formula (d-1) or (d-2), R ^{1 to} R ⁵ are each independently a hydrocarbon group having 1 to 50 carbon atoms.
The number of carbon atoms of the hydrocarbon is preferably 1 to 50, more preferably 4 to 40, still more preferably 6 to 30, and even more preferably 8 to 20.
^{Examples of the hydrocarbon group include the same hydrocarbon groups that can be selected as Ra} and R ^b in the above general formula (c-1), but an alkyl group or an alkenyl group is preferable, and an alkyl group is used. More preferably it is a group.
The alkyl group and the alkenyl group may be a straight chain or a branched chain.

In the general formula (d-1), a is an integer of 1 to 3 (preferably 1), b is an integer of 1 to 3 (preferably 1), and c is an integer of 0 to 3 (preferably 0 or 1, More preferably 0), d is an integer of 1 to 3 (preferably 1), e is an integer of 1 to 3 (preferably 1), a + b + e is an integer of 3 to 6, and c + d is an integer of 1 to 5. is there.

In the general formula (d-2), f is an integer of 0 to 3, g is an integer of 0 to 3, and f + g is an integer of 1 to 3.
h is an integer of 0 to 4, i is an integer of 0 to 3, and h + i is an integer of 1 to 6.
j is an integer of 0 to 3, k is an integer of 1 to 3, and j + k is an integer of 1 to 5.
m is an integer of 1 to 3, and f + g + h + i + m is an integer of 3 to 8.

In the lubricating oil composition of one aspect of the present invention, the content of the component (D) is excellent even when used in a high temperature environment of more than 160 ° C. based on the total amount (100% by mass) of the lubricating oil composition. From the viewpoint of producing a lubricating oil composition having heat resistance, it is preferably 0.5 to 15.0% by mass, more preferably 0.7 to 13.0% by mass, and further preferably 1.0 to 12.0% by mass. %, More preferably 2.0 to 10.0% by mass.

<Zinc dithiophosphate>
The lubricating oil composition of the present invention may further contain zinc dithiophosphate (ZnDTP), but the content of zinc dithiophosphate in terms of zinc atom is based on the total amount (100% by mass) of the lubricating oil composition. It is limited to less than 500 mass ppm.
Lubricating oil compositions having a zinc dithiophosphate content of more than 500 mass ppm have problems in terms of metal corrosion resistance.

As described above, ZnDTP is more decomposed in a high temperature environment of more than 160 ° C., and sulfuric acid and phosphoric acid are likely to be generated, which is a factor of promoting corrosion of metal parts.
However, since the lubricating oil composition of the present invention contains the components (B) to (D), the decomposition of ZnDTP can be suppressed to some extent even in a high temperature environment of more than 160 ° C. Therefore, if the content of ZnDTP is less than 500 mass ppm, the abrasion resistance can be further improved by the presence of ZnDTP while maintaining good metal corrosion resistance.

From the above viewpoint, in the lubricating oil composition of one aspect of the present invention, the content of zinc dithiophosphate in terms of zinc atom is preferably less than 400% by mass based on the total amount (100% by mass) of the lubricating oil composition. , More preferably less than 350 mass ppm, even more preferably less than 300 mass ppm, even more preferably less than 280 mass ppm. Further, from the viewpoint of improving wear resistance, it is preferably 100 mass ppm or more.

Further, in the lubricating oil composition of one aspect of the present invention, the content of zinc dithiophosphate may be adjusted so that the content in terms of zinc atom is within the above range, but the lubricating oil composition. Based on the total amount (100% by mass), it is preferably less than 0.50% by mass, more preferably less than 0.40% by mass, and further preferably less than 0.30% by mass. Further, from the viewpoint of improving wear resistance, it is preferably 0.10% by mass or more.

Examples of the zinc dithiophosphate used in one embodiment of the present invention include compounds represented by the following general formula (e-1).

In the above formula (e-1), R ^{11 to} R ¹⁴ each independently represent a hydrocarbon group.
Examples of the hydrocarbon group include the same hydrocarbon groups that can be selected as ^Ra and R ^b in the above general formula (c-1), but alkyl groups are preferable.
The alkyl group may be a straight chain alkyl group or a branched chain alkyl group, but a branched chain alkyl group is preferable.
The ^{hydrocarbon groups that can be selected as R 11 to} R ¹⁴ have preferably 1 to 20, more preferably 3 to 16, still more preferably 4 to 12, and even more preferably 5 to 10.

<Metallic cleaner>
The lubricating oil composition of the present invention may contain a metal-based cleaning agent, but the content of the metal-based cleaning agent in terms of metal atoms is based on the total amount (100% by mass) of the lubricating oil composition. It is limited to less than 600 mass ppm.
A lubricating oil composition having a content of 600 mass ppm or more tends to have a reduced wear resistance.
However, since the lubricating oil composition of the present invention contains the component (D), if the content of the metal-based cleaning agent is less than 600 mass ppm, the decrease in wear resistance can be suppressed to some extent. The heat resistance can be further improved by the presence of the metal-based lubricant.

In the lubricating oil composition of one aspect of the present invention, the content of the metal-based cleaning agent in terms of metal atoms is based on the total amount (100% by mass) of the lubricating oil composition, from the viewpoint of maintaining good wear resistance. Therefore, it is preferably less than 550 mass ppm, more preferably less than 500 mass ppm, still more preferably less than 470 mass ppm, still more preferably less than 300 mass ppm.

Examples of the metal-based cleaning agent include organic acid metal salt compounds containing metal atoms selected from alkali metals and alkaline earth metals, and specifically, metal atoms selected from alkali metals and alkaline earth metals. Examples thereof include metal salicylates, metal phenates, and metal sulfonates containing.
As the metal atom contained in the metal-based cleaning agent, sodium, calcium, magnesium, or barium is preferable, and calcium is more preferable, from the viewpoint of improving heat resistance.
That is, the metal-based cleaning agent used in one aspect of the present invention is preferably one or more selected from calcium salicylate, calcium phenate, and calcium sulfonate.

In one aspect of the present invention, the metal-based cleaning agent may be any of a neutral salt, a basic salt, a hyperbasic salt, and a mixture thereof.
The total base value of the metal-based cleaning agent is preferably 0 to 600 mgKOH / g.
In one aspect of the present invention, when the metal-based cleaning agent is a basic salt or a hyperbasic salt, the total base value of the metal-based cleaning agent is preferably 10 to 600 mgKOH / g, more preferably. Is 20-500 mgKOH / g.
In the present specification, the term "base value" refers to JIS K2501 "Petroleum products and lubricating oil-neutralization value test method" at 7: 2003. It means the base value by the perchloric acid method measured according to.

<Additives for other lubricating oils>
The lubricating oil composition of one aspect of the present invention may contain additives for lubricating oil other than the above components as long as the effects of the present invention are not impaired. In the following description, the other additive for lubricating oil is also referred to as "component (E)".
Other additives for lubricating oil include, for example, antioxidants, viscosity index improvers, pour point lowering agents, abrasion resistant agents, extreme pressure agents, metal-based friction modifiers, rust inhibitors, metal inactivating agents, and the like. Examples include anti-emulsifiers and antifoaming agents.
Each of these additives for lubricating oil may be used alone or in combination of two or more.

The content of each of these additives for lubricating oil can be appropriately adjusted within a range that does not impair the effects of the present invention, but is usually 0.001 based on the total amount (100% by mass) of the lubricating oil composition. It is ~ 15% by mass, preferably 0.005 to 10% by mass, more preferably 0.01 to 5% by mass, still more preferably 0.03 to 2% by mass.

In this specification, additives such as a viscosity index improver and an antifoaming agent are diluted with a part of the above-mentioned base oil (A) in consideration of handleability and solubility in the base oil (A). It may be blended with other components in the form of a dissolved solution. In such a case, in the present specification, the above-mentioned content of additives such as antifoaming agent and viscosity index improver means the content in terms of active ingredient (resin content equivalent) excluding diluted oil. ..

Examples of the antioxidant include amine-based antioxidants, phenol-based antioxidants, molybdenum-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.
Among these, one or more selected from amine-based antioxidants and phenol-based antioxidants is preferable, and it is more preferable to use amine-based antioxidants and phenol-based antioxidants in combination.

Examples of the viscosity index improver include non-dispersive polymethacrylate, dispersed polymethacrylate, olefin-based copolymer (for example, ethylene-propylene copolymer, etc.), dispersed olefin-based copolymer, and styrene-based copolymer. (For example, a styrene-diene copolymer, a styrene-isoprene copolymer, etc.) and the like can be mentioned.
The weight average molecular weight (Mw) of these viscosity index improvers is usually 3,000 to 1,000,000, preferably 5,000 to 800,000, and more preferably 10,000 to 700,000. , Is appropriately set according to the type of polymer.

Examples of the pour point lowering agent include ethylene-vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene and the like.

Examples of the abrasion resistant agent or extreme pressure agent include sulfur-containing compounds such as molybdenum dithiocarbamate, molybdenum dithiophosphate, disulfides, olefin sulfides, fats and oils sulfide, sulfide esters, thiocarbonates, thiocarbamates, and polysulfides. Phosphoric acid esters, phosphoric acid esters, phosphonic acid esters, and phosphorus-containing compounds such as amine salts or metal salts thereof; thioa-phosphate esters, thiophosphate esters, thiophosphonic acid esters, and these. Examples thereof include sulfur and phosphorus-containing compounds such as amine salts or metal salts of the above.

Examples of the metal-based friction modifier include molybdenum-based friction modifiers such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdenum acid.

Examples of the rust preventive agent include fatty acids, alkenyl succinic acid half esters, fatty acid sequels, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, alkyl polyoxyethylene ethers and the like.

Examples of the metal inactivating agent include benzotriazole-based compounds, tolyltriazole-based compounds, thiazizol-based compounds, imidazole-based compounds, pyrimidine-based compounds and the like.

Examples of the anti-emulsifier include anionic surfactants such as sulfate ester salt of castor oil and petroleum sulfonate; cationic surfactants such as quaternary ammonium salt and imidazolines; polyoxyalkylene polyglycol and its dicarboxylic acid. Esters; alkylene oxide adducts of alkylphenol-formaldehyde polycondensates; and the like.

Examples of the defoaming agent include silicone oil, fluorosilicone oil, fluoroalkyl ether and the like.

From the viewpoint of reducing the ash content derived from the metal content, the lubricating oil composition of one aspect of the present invention preferably contains as little molybdenum-based compound as possible.
Specifically, the content of the molybdenum-based compound in terms of molybdenum is preferably less than 100% by mass, more preferably less than 50% by mass, still more preferably, based on the total amount (100% by mass) of the lubricating oil composition. It is less than 10 mass ppm.

[Manufacturing method of lubricating oil composition]
The method for producing the lubricating oil composition of the present invention is not particularly limited, and examples thereof include a production method having the following step (I).
Step (I): An ashless dispersant (B) containing a non-borated alkenyl succinate imide (B1) and a borated alkenyl succinate imide (B2) in a base oil (A), a thiadiazole compound (C). , And the step of blending the aromatic carboxylic acid ester (D) having one or more hydroxyl groups.

In the step (I), the component (E) may be blended at the same time as the components (A) to (D).
However, in step (I), the content of the metal-based cleaning agent in terms of metal atoms is adjusted to be less than 600 mass ppm based on the total amount of the lubricating oil composition.

In this step, each component to be blended is as described above, and a suitable type of component and the content of each component are also as described above.
Further, each component to be blended in the step (I) may be blended after adding a diluting oil or the like to form a solution (dispersion). After blending each component, it is preferable to stir and uniformly disperse by a known method.

[Various properties of lubricating oil composition]
Kinematic viscosity at 100 ° C. for one embodiment of the lubricating oil composition of the present invention is preferably 8.0~20.0mm ² / s, more preferably 9.3~18.0mm ² / s, more preferably 9. It is 3 to 16.3 mm ² / s.
Further, the kinematic viscosity at 100 ° C., preferably 8.0~20mm ² / s, more preferably 8.0~16.3mm ² / s, more preferably 8.0~12.5mm ² / s.

The viscosity index of the lubricating oil composition according to one aspect of the present invention is preferably 100 or more, more preferably 110 or more, still more preferably 120 or more.

In the lubricating oil composition of one aspect of the present invention, the content of phosphorus atoms is preferably 400 from the viewpoint of reducing the load on the exhaust gas aftertreatment device based on the total amount (100% by mass) of the lubricating oil composition. It is less than mass ppm, more preferably less than 350 mass ppm, still more preferably less than 300 mass ppm, even more preferably less than 250 mass ppm.

In the lubricating oil composition of one aspect of the present invention, the content of sulfur atoms is preferably 500 to 5000 mass ppm, more preferably 700 to 4500 mass ppm, based on the total amount (100 mass%) of the lubricating oil composition. , More preferably 900 to 4000 mass ppm, and even more preferably 105 to 3500 mass ppm.

In the lubricating oil composition of one aspect of the present invention, the sulfated ash content is preferably less than 0.30% by mass, more preferably less than 0.25% by mass, based on the total amount (100% by mass) of the lubricating oil composition. It is more preferably less than 0.20% by mass, and even more preferably less than 0.05% by mass.
If the sulfuric acid ash content is less than 0.30% by mass, it is possible to suppress the functional deterioration of the catalyst provided in the exhaust gas aftertreatment device, and the ash content derived from the metal content is prevented from accumulating on the DPF. It can be prevented.
In addition, in this specification, sulfate ash content means the value measured according to JIS K2272: 1998.

When the lubricating composition of one aspect of the present invention is subjected to a metal corrosiveness test in accordance with the test tube method of JIS K2513: 2000 under a temperature condition of 100 ° C., the discoloration number specified is preferably. It is 1 or 2, and more preferably 1.
Further, when a test according to the test tube method of JIS K2513: 2000 is performed on the lubricating composition of one aspect of the present invention under a temperature condition of 165.5 ° C., the discoloration number specified is preferable. Is 1 or 2.
In this specification, detailed conditions of the test based on the test tube method of JIS K2513: 2000 are as described in Examples described later.

In the lubricating oil composition of one aspect of the present invention, the value of the wear mark diameter measured based on the methods and conditions of Examples described later is preferably 450 μm or less, more preferably 440 μm or less, still more preferably 435 μm or less, and more. More preferably, it is 430 μm or less.

When a hot tube test conforming to JPI-5S-55-99 was performed on the lubricating oil composition of one aspect of the present invention under a temperature condition of 280 ° C., the identified merit scores were preferably 8. It is 0 or more, more preferably 8.5 or more, still more preferably 9.0 or more, and even more preferably 9.5 or more.

Further, the deteriorated oil obtained after conducting an ISOT test based on JIS K 2514-1: 2013 at 165.5 ° C. for 72 hours on the lubricating oil composition according to one aspect of the present invention at 280 ° C. When a hot tube test conforming to JPI-5S-55-99 was performed under temperature conditions, the identified merit score was preferably 7.0 or higher, more preferably 7.5 or higher, and further preferably 8.0. The above is even more preferably 8.5 or more.
In the present invention, the detailed conditions of the hot tube test and the detailed conditions of the ISOT test based on JIS K 2514-1: 2013 are as described in Examples described later.

[Use of lubricating oil composition]
The lubricating oil composition of the present invention has excellent wear resistance and can exhibit excellent metal corrosion resistance and heat resistance even when used in a high temperature environment of more than 160 ° C.
The lubricating oil composition of the present invention is used for an internal combustion engine, and is particularly preferably used for an internal combustion engine including parts having a maximum temperature of more than 160 ° C.
Examples of the internal combustion engine include a gasoline engine, a diesel engine, a gas engine, and the like mounted on a two-wheeled vehicle, a four-wheeled vehicle, a generator, a ship, and the like.
Since the lubricating oil composition of the present invention has a reduced metal content, it should be noted that an internal combustion engine equipped with an exhaust gas aftertreatment device, or a spark ignition type internal combustion engine equipped with a spark ignition plug and laser ignition provided with a laser spark plug. It is also preferable to be used in a type internal combustion engine.

The present invention may also provide an internal combustion engine shown in the following [1] and a usage method shown in the following [2].
[1] A base oil (A), an ashless dispersant (B) containing a non-borated alkenyl succinate imide (B1) and a borated alkenyl succinate imide (B2), a thiadiazole compound (C), and Contains an aromatic carboxylic acid ester (D) having one or more hydroxyl groups,
The content of the component (C) is 0.2 to 1.2% by mass,
The zinc atom equivalent content of zinc dithiophosphate is less than 500 mass ppm.
The content of the metal-based cleaning agent in terms of metal atoms is less than 600 mass ppm.
An internal combustion engine using a lubricating oil composition.
[2] A base oil (A), an ashless dispersant (B) containing a non-borated alkenyl succinate imide (B1) and a borated alkenyl succinate imide (B2), a thiadiazole compound (C), and Contains an aromatic carboxylic acid ester (D) having one or more hydroxyl groups,
The content of the component (C) is 0.2 to 1.2% by mass,
The zinc atom equivalent content of zinc dithiophosphate is less than 500 mass ppm.
The content of the metal-based cleaning agent in terms of metal atoms is less than 600 mass ppm.
A method of using a lubricating oil composition, which uses the lubricating oil composition in an internal combustion engine.

Regarding the lubricating oil composition used in the above [1] and [2], the preferable mode of each component, the suitable properties of the lubricating oil composition and the like are as described above.
Further, the internal combustion engine according to the above [1] and [2] is preferably an internal combustion engine including parts having a maximum temperature of more than 160 ° C., and includes parts having a maximum temperature of more than 160 ° C. Further, it is more preferable that the internal combustion engine is provided with an exhaust gas aftertreatment device. Further, a spark ignition type internal combustion engine including a spark ignition plug and a laser ignition type internal combustion engine including a laser ignition plug are preferable.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples. In addition, each component used in Examples and Comparative Examples and various properties of the obtained lubricating oil composition were measured according to the following method.

<Kinematic viscosity, viscosity index>
Measured or calculated according to JIS K 2283: 2000.
<Contents of boron atom, phosphorus atom, calcium atom, zinc atom, and molybdenum atom>
Measured according to JPI-5S-38-03.
<Nitrogen atom content>
Measured according to JIS K2609: 1998.
<Sulfur atom content>
Measured according to JIS K2541-6: 2013.
<Sulfate ash>
Measured according to JIS K2272: 1998.

Examples 1-12, Comparative Examples 1-8
Lubrication in which the base oils and various additives shown below are added in the blending amounts shown in Tables 1 to 3 and mixed thoroughly so that the kinematic viscosity at 100 ° C. is 12.0 to 13.0 mm ^{2 / s.} Each oil composition was prepared.
Details of the base oil and various additives used in Examples and Comparative Examples are as shown below.

(Component (A))
"Base oil (a)": 500N mineral oil subjected to hydrorefining treatment, classified into Group 2 in the API base oil category, 40 ° C. kinematic viscosity = 89.3 mm ² / s, 100 ° C. kinematic viscosity = 10 .9 mm ² / s, viscosity index = 107.
(Ingredient (B1))
- "non-borated alkenyl succinic monoimide (b1)": ^{R A} in the general formula (b1) alkenyl succinic monoimide represented by formula ((b1) has a number average molecular weight (Mn) 1000 (It is a polybutenyl group), nitrogen atom content = 2.0% by mass.
(Ingredient (B2))
· "Boronated alkenyl succinic monoimide (b2-1)": R ^A in the boron modified product of an alkenyl succinic monoimide represented by the general formula (b-1) (formula (b-1) include the number average It is a polybutenyl group having a molecular weight (Mn) of 1000), nitrogen atom content = 1.8% by mass, boron atom content = 2.0% by mass, B / N = 1.11.
· "Boronated alkenyl succinic monoimide (b2-2)": R ^A in the boron modified product of an alkenyl succinic monoimide represented by the general formula (b-1) (formula (b-1) include the number average It is a polybutenyl group having a molecular weight (Mn) of 1000), nitrogen atom content = 1.2% by mass, boron atom content = 1.3% by mass, B / N = 1.08.

(Component (C))
-Thiadiazole-based compound (c1): A compound represented by the following formula (ci). Sulfur atom content = 35.0% by mass.
-Thiadiazole-based compound (c2): A compound represented by the following formula (c-ii). Sulfur atom content = 33.6% by mass.

(Component (D))
Aromatic carboxylic acid ester (d1): dodecyl salicylic acid dodecylphenyl ester, R ¹ and R ^{2 in the} general formula (d-1) are dodecyl groups (-C ₁₂ H ₂₅ ), a = b = d = e = 1, c = 0 compound.

(Other ingredients)
^{ZnDTP: zinc dithiophosphate, a compound in which R 11 to} R ¹⁴ in the general formula (e-1) are 2-ethylhexyl groups, phosphorus atom content = 8.2% by mass, zinc atom content = 9 0.0% by mass, sulfur atom content = 17.1% by mass.
-Ca-based cleaning agent: Ca phenate, calcium atom content = 9.25% by mass.
-Antioxidant: A mixture of an amine-based antioxidant and a phenol-based antioxidant.
-Mixed additive: A mixed additive containing antifoaming agent, pour point lowering agent, etc.

Further, the following tests (1) to (3) were carried out in this order for the prepared lubricating oil composition. These results are shown in Tables 1-3.
If the result of the (1) metal corrosion test was poor, the subsequent (2) abrasion resistance test and (3) hot tube test were not performed. Further, when (2) the result of the abrasion resistance test was poor, (3) the hot tube test was completed without being performed.

[(1) Metal corrosiveness test]
The temperature conditions were set to 100 ° C. and 165.5 ° C., and the test was performed in accordance with the test tube method of JIS K2513: 2000.
Then, after the test, the copper plate was taken out, and the degree of discoloration of the copper plate was specified according to the method for determining the copper plate specified in JIS K2513: 2000, and the discoloration number under each temperature condition was specified. The discoloration number has four stages of 1 to 4, and it can be said that the smaller the value, the more the discoloration is suppressed and the effect of suppressing metal corrosiveness is high.
When the discoloration number was 1 or 2 under both the temperature conditions of 100 ° C. and 165.5 ° C., it was judged that the metal corrosion resistance was good. Then, the following (2) abrasion resistance test was performed only on the lubricating oil composition judged to have good metal corrosion resistance.

[(2) Abrasion resistance test]
Using a high-speed reciprocating friction tester TE77 (manufactured by Phoenix Tribology), a lubricating oil composition was introduced between the test plate and the test ball, and the test ball was moved under the following conditions to perform the test, and after the test. The wear mark diameter of the test ball was measured.
-Test plate Material: SUJ2, Shape: Length 58 mm x Width 38 mm x Thickness 3.9 mm
・ Test ball material: SUJ2, diameter 10 mm
・ Refueling conditions: Oil bath, oil volume 3mL
-Load: 50N (5 minutes) → 100N (5 minutes) → 150N (5 minutes) → 200N (5 minutes)
・ Temperature: 100 ℃
・ Frequency: 10Hz
It can be said that the smaller the value of the wear mark diameter, the more excellent the wear resistance of the lubricating oil composition.
When the value of the wear mark diameter is 450 μm or less, it is judged that the wear resistance is good. Then, the following (3) hot tube test was performed only on the lubricating oil composition judged to have good wear resistance.

[(3) Hot tube test]
The prepared lubricating oil composition was placed in a glass tube and set to a test temperature of 280 ° C., and a hot tube test conforming to JPI-5S-55-99 was performed. The glass tube after the test was evaluated at 0 points (black) to 10 points (colorless) (merit score) in 0.5 increments, and the score of the new oil was determined in 21 steps. The higher the score, the better the high temperature cleanliness.
Further, a copper piece and an iron piece were added to the test oil (lubricating oil composition) as catalysts, and an ISOT test conforming to JIS K 2514-1: 2013 was carried out at 165.5 ° C. for 72 hours to forcibly deteriorate the test oil. , Deteriorated oil. Then, the deteriorated oil was subjected to a hot tube test under the same conditions as described above, and the score of the deteriorated oil was determined.
When the score of the new oil is 8.0 or more and the score of the deteriorated oil is 7.0 or more, it is judged that the heat resistance is good.

As a result, the lubricating oil compositions prepared in Examples 1 to 12 have excellent wear resistance and can exhibit excellent metal corrosion resistance and heat resistance even when used in a high temperature environment of more than 160 ° C. It became.
On the other hand, the lubricating oil compositions prepared in Comparative Examples 2 to 5 and 7 have poor metal corrosiveness test results and poor metal corrosiveness resistance, assuming use in a high temperature environment of more than 160 ° C. It became.
Further, the lubricating oil compositions prepared in Comparative Examples 6 and 8 had good metal corrosion resistance, but were inferior in wear resistance.
Further, the lubricating oil composition prepared in Comparative Example 1 had a low score in the hot tube test, resulting in a problem in heat resistance.

Claims (12)

Base oil (A),
An ashless dispersant (B) containing a non-borated alkenyl succinate imide (B1) and a boborated alkenyl succinate imide (B2),
Thiadiazole compound (C) and aromatic carboxylic acid ester (D) having 1 or more hydroxyl groups
A lubricating oil composition containing
The content of the component (C) is 0.2 to 1.2% by mass based on the total amount of the lubricating oil composition.
The content of zinc dithiophosphate in terms of zinc atoms is less than 500 mass ppm based on the total amount of the lubricating oil composition.
The content of the metal-based cleaning agent in terms of metal atoms is less than 600 mass ppm based on the total amount of the lubricating oil composition.
Lubricating oil composition used for internal combustion engines. The lubricating oil composition according to claim 1, wherein the content ratio [(D) / (B2)] of the component (D) to the component (B2) is 0.1 to 5.0 by mass ratio. The lubricating oil composition according to claim 1 or 2, wherein the content of the component (D) is 0.5 to 15.0% by mass based on the total amount of the lubricating oil composition. The component (D) is one or more selected from the compound (D1) represented by the following general formula (d-1) and the compound (D2) represented by the following general formula (d-2). The lubricating oil composition according to any one of claims 1 to 3.

[In the general formula (d-1) or (d-2), R ^{1 to} R ⁵ are each independently a hydrocarbon group having 1 to 50 carbon atoms.
In the general formula (d-1), a is an integer of 1 to 3, b is an integer of 1 to 3, c is an integer of 0 to 3, d is an integer of 1 to 3, and e is an integer of 1 to 3. Yes, a + b + e is an integer of 3 to 6, and c + d is an integer of 1 to 5.
In the general formula (d-2), f is an integer of 0 to 3, g is an integer of 0 to 3, and f + g is an integer of 1 to 3.
h is an integer of 0 to 4, i is an integer of 0 to 3, and h + i is an integer of 1 to 6.
j is an integer of 0 to 3, k is an integer of 1 to 3, and j + k is an integer of 1 to 5.
m is an integer of 1 to 3, and f + g + h + i + m is an integer of 3 to 8. ] The lubricating oil composition according to any one of claims 1 to 4, wherein the content of the component (B2) in terms of boron atom is 200 to 3000 mass ppm based on the total amount of the lubricating oil composition. The item according to any one of claims 1 to 5, wherein the content ratio [B / N] of the boron atom and the nitrogen atom in the component (B2) is 0.3 to 2.5 in terms of mass ratio. Lubricating oil composition. The lubricating oil composition according to any one of claims 1 to 6, wherein the content of the component (B1) in terms of nitrogen atoms is 400 to 3000 mass ppm based on the total amount of the lubricating oil composition. The lubrication according to any one of claims 1 to 7, wherein the content ratio [B / N] of the boron atom and the nitrogen atom of the component (B) is 0.10 to 1.30 in terms of mass ratio. Oil composition. The lubricating oil composition according to any one of claims 1 to 8, wherein the component (C) is a compound represented by the following general formula (c-1).

[In the general formula (c-1), p and q are independently integers of 0 to 5, and p + q is 1 or more. r and s are each independently an integer of 1-5.
R ^a and R ^b are heteroatom-containing groups each independently containing one or more hydrogen atoms, hydrocarbon groups, or oxygen atoms, nitrogen atoms, and sulfur atoms. ] The lubricating oil composition according to any one of claims 1 to 9, wherein the content of the molybdenum-based compound in terms of molybdenum is less than 100 mass ppm based on the total amount of the lubricating oil composition. The lubricating oil composition according to any one of claims 1 to 10, wherein the phosphorus atom content is less than 400 mass ppm based on the total amount of the lubricating oil composition. The lubricating oil composition according to any one of claims 1 to 11, wherein the sulfated ash content is less than 0.30% by mass based on the total amount of the lubricating oil composition.