JPH1180771A - Lubricating oil composition for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in abrasion resistance, cleanness, heat resistance and oxidation stability, and considerably lengthened in service life, by incorporating a lubricating base oil with a combination of alkaline earth metal-based cleaning agents each having specific total base number in specified proportions. SOLUTION: This composition is obtained by incorporating a lubricating base oil 5-40 mm<2> /s in dynamic viscosity at 100 deg.C with (A) 0.1-2.5 wt.%, in terms of alkaline earth metal concentration, of an alkaline earth metal salicylate 60-220 mgKOH/g in total base number determined by the perchloric acid method (hereafter, abbreviated as total base number) and (B) 0.01-1 wt.%, in terms of alkaline earth metal concentration, of (1) an alkaline earth metal salicylate >220 mgKOH/g but <=400 mgKOH/g in total base number and/or (2) an alkaline earth metal sulfonate 20-200 mgKOH/g in total base number. Furthermore, incorporation of an alkaline earth metal phenate 100-450 mgKOH/g in total base number in this composition improves, in particular, seizing-proof performance of this composition, therefore being favorable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil composition for a diesel engine, and more particularly to a lubricating oil composition useful for use in a land-based diesel engine and a marine diesel engine. The present invention provides a lubricating oil composition for a diesel engine that has excellent wear resistance, cleanliness, heat resistance, and oxidation stability, and particularly has a significantly improved wear resistance, thereby extending the life of the lubricating oil. can do.

[0002]

2. Description of the Related Art Diesel engines have a higher combustion pressure than gasoline engines, so that the temperature in the combustion chamber becomes high, which creates a harsh environment for lubricating oil. In addition, since the combustion process of a diesel engine is different from that of a gasoline engine, incomplete combustion is likely to occur, and soot and combustion residues are often generated. For this reason, it is inevitable that solid components such as soot, combustion residues, and degraded lubricating oil are mixed into the diesel engine oil.
When insoluble solids are mixed into diesel engine oil,
Lubrication problems may occur. For example, these insolubles accumulate around pistons and high temperature sliding parts, increase the viscosity of lubricating oil, cause problems such as increased wear and power loss, and increase the clogging speed of oil filters. For example, lubrication troubles may occur. Therefore, it has been desired to solve these problems by formulating a lubricating oil.

Conventional measures against such solids include (1) a method in which insoluble solids such as soot mixed in lubricating oil are finely and uniformly dispersed in lubricating oil with a detergent and dispersant; A method based on a concept completely opposite to the idea, that is, (2) a method in which insoluble solids are agglomerated by agglomeration to such an extent that sedimentation or deposition does not occur, and captured and removed by a filter has been proposed.

However, these conventional methods use a lubricating oil that emphasizes the particle size and dispersibility of combustion residues such as soot, so that the lubricating oil has poor performance such as oxidation stability, heat resistance and cleanliness. It was not sufficient, and a satisfactory result was not obtained. In particular, in various types of diesel engines that have been highly efficient in recent years, solving these problems has been one of the major technical issues.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of conventional lubricating oils and to provide excellent wear resistance, cleanliness, heat resistance and oxidation stability, and to greatly extend the life of lubricating oils. ,
An object of the present invention is to provide a diesel engine oil capable of maximizing economic benefits.

[0006]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, a lubricating oil composition having a specific constitution has excellent abrasion resistance, cleanliness and heat resistance. It has been found that the composition has oxidative stability and, in particular, its wear resistance lasts for a long period of time, and has completed the present invention.

That is, the invention of claim 1 of the present invention provides
A lubricating base oil having a kinematic viscosity at 00 ° C. of 5 to 40 mm ² / s, based on the total amount of the composition, (1) an alkaline earth metal salicylate having a total base number by a perchloric acid method of 60 to 220 mgKOH / g. 0.1 to 2.5% by mass in terms of alkaline earth metal concentration and (2) (a) the total base number by the perchloric acid method exceeds 220 mgKOH / g,
mgKOH / g or less alkaline earth metal salicylate and / or (b) a total base number by the perchloric acid method of 2
An object of the present invention is to provide a lubricating oil composition for a diesel engine, comprising an alkaline earth metal sulfonate of 0 to 200 mgKOH / g in terms of an alkaline earth metal concentration of 0.01 to 1% by mass. According to a second aspect of the present invention, there is provided the lubricating oil composition for a diesel engine according to the first aspect, wherein (3) the total base number by the perchloric acid method is 100 to 100.
A lubricating oil composition for a diesel engine comprising an alkaline earth metal phenate of 450 mg KOH / g in terms of an alkaline earth metal concentration of 0.05 to 2% by mass.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the contents of the present invention will be described in detail. The base oil used in the present invention has a kinematic viscosity at 100 ° C. of 5 mm ² / s or more, preferably 10 mm ² / s or more, and 40 mm ² / s or less, preferably 35 mm ² / s or less.
² / s or less. The kinematic viscosity at 100 ° C of the base oil is 5
mm in a case of less than ² / s is not preferable for detergency and heat resistance is inferior, and preferably for poor stability and heat resistance oxide if the kinematic viscosity at 100 ° C. of the base oil exceeds 40 mm ² / s Absent.

Although the viscosity index of the base oil used in the present invention is not particularly limited, it is desirably 80 or more, preferably 90 or more. The lubricating base oil used in the present invention is not particularly limited, and any lubricating base oil can be used regardless of whether it is a mineral oil or a synthetic oil as long as it is usually used as a base oil for lubricating oil.

[0010] As the mineral oil-based lubricating base oil, for example, a lubricating oil fraction obtained by distilling crude oil under normal pressure and reduced pressure is used.
Solvents such as paraffinic and naphthenic oils can be used, which are purified by appropriately combining solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment. .

Examples of synthetic lubricating base oils include poly-α-olefins (polybutene, 1-octene oligomer, 1-decene oligomer, etc.) or hydrides thereof, alkylbenzenes, alkylnaphthalenes, diesters (ditridecyl glutarate). Di-2-ethylhexyl adipate, di-3-ethylhexyl adipate,
Diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, etc.), polyester (trimellitic acid ester, pyromellitic acid ester, etc.), polyol ester (trimethylolpropane caprylate, trimethylolpropaneperargonate,
Pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, etc.), polyoxyalkylene glycol, dialkyl diphenyl ether, polyphenyl ether and the like can be used. These base oils may be used alone or in combination of two or more kinds at an arbitrary ratio.

The alkaline earth metal salicylate (hereinafter referred to as component (1)) having a total base number by the perchloric acid method of 60 to 220 mg KOH / g according to the present invention has a total base number by the perchloric acid method of 60 mg KOH / g. g, preferably 140 mg KOH / g or more, and 220 mg KOH / g
It is important that the H / g is not more than 200 mgKOH / g, more preferably not more than 190 mgKOH / g. Component (1) has a total base number of 60 mg KOH /
When the amount is less than 2 g, the required addition amount of the component (1) increases, so that a large amount of a soap-based component generated in the neutralization reaction lowers the oxidation stability, which is not preferable. Further, the total base number is 220 mgKOH / g. If it exceeds, the heat resistance and the oxidation stability are undesirably reduced.

The total base number by the perchloric acid method in the present invention is measured in accordance with the method specified in "Petroleum products and lubricating oils-Neutralization number test method" of JIS K 2501 (1996). Mean value.

The metal ratio of the component (1) is arbitrary, but is usually 1 or more, preferably 2 or more, and 3.5 or less, preferably 3.3 or less, more preferably 3.2 or less. It is desirable. By setting the metal ratio of the component (1) to 1 or more, the amount of the soap-based component in the required additive can be suppressed, so that a decrease in oxidative stability due to the soap-based component generated by the neutralization reaction can be prevented, Further, by setting the metal ratio to 3.5 or less, favorable heat resistance and oxidation stability can be obtained, which are respectively preferable.

The metal ratio of the alkaline earth metal salicylate in the present invention is a number represented by the following formula (1). The alkaline earth metal content (g) in the alkaline earth metal salicylate additive referred to herein is determined by the Japan Petroleum Institute standard JIP.
Quantify and calculate according to the elemental analysis method of -5S-38-92. The salicylic acid content (mol) in the alkaline earth metal salicylate additive is calculated by the following method. First, 5 mL of 6N hydrochloric acid is added to 1 g of the alkaline earth metal salicylate additive, and the mixture is heated at 70 to 80 ° C. for 30 minutes. This solution is extracted with 20 mL of benzene, the amount (mol) of salicylic acid in the extract is quantified by high performance liquid chromatography, and the salicylic acid content (mol) in the sample is calculated. As a standard substance for high performance liquid chromatography, salicylic acid having the same substituent as the salicylate salt contained in the alkaline earth metal salicylate additive is used. The measurement conditions of the high performance liquid chromatography are as follows. 3. Column: UNSK Q 100-10 (reverse phase system);
6 × 250 mm mobile phase: hexane / chloroform / trifluoroacetic acid 5
0: 50: 1 Mixed solvent flow rate: 1 mL / min Detector: UV (wavelength 254 nm)

[0016]

(Equation 1)

Examples of the alkaline earth metal in the component (1) include calcium, magnesium and barium. Among them, calcium and magnesium are particularly preferred. Specific examples of component (1) include so-called basic salicylates, carbonate overbased (ultrabasic) salicylates, and borate overbased (ultrabasic) salicylates. Also, the production method of the component (1) is not particularly limited, and specifically, for example, contains 12 to 12 carbon atoms.
Alkaline salicylic acid having 1-2, preferably 14-18 alkyl groups in the presence or absence of elemental sulfur in the presence of an alkaline earth metal base (such as an oxide or hydroxide of an alkaline earth metal) A so-called neutral (normal salt) alkaline earth metal salicylate obtained by reacting with a so-called basic alkaline earth metal obtained by heating an excess salt or base of an alkaline earth metal in the presence of water. So-called carbonate overbased (ultrabasic) alkaline earth metal salicylates obtained by reacting a neutral alkaline earth metal salicylate with an alkaline earth metal base in the presence of carbon dioxide gas; Reactive alkaline earth metal salicylates with alkaline earth metal bases and boric acid compounds such as boric acid or boric anhydride, Or so-called borate overbased (ultrabasic) produced by reacting a carbonate overbased (ultrabasic) alkaline earth metal salicylate with a boric acid compound such as boric acid or boric anhydride. Salicylates; and mixtures thereof.

The carbonate overbased (ultrabasic) salicylate is an alkaline earth metal neutral salt of an alkyl salicylic acid that is overbased by an alkaline earth metal carbonate, and when present in oil, The alkaline earth metal carbonate has a dispersion structure in which the alkaline earth metal salt of alkyl salicylic acid is dispersed in oil. Borate overbased (ultrabasic) salicylate made from neutral alkaline earth metal salicylate is obtained by overbasing alkaline earth metal neutral salt of alkyl salicylic acid with alkaline earth metal borate. And when present in the oil, has a dispersion structure in which the borate of the alkaline earth metal is dispersed in the oil by the alkaline earth metal alkylsalicylate. Borate overbased (ultrabasic) salicylate, which is made from carbonate overbased (ultrabasic) alkaline earth metal salicylate, is a neutral alkaline earth metal carbonate of alkyl salicylic acid. And overbased with alkaline earth metal borates and, when present in the oil, a mixture of alkaline earth metal carbonate and alkaline earth metal borate forms an alkaline earth metal salt of alkylsalicylic acid. It has a dispersion structure dispersed in oil by metal salts.

Specific examples of the alkyl group of alkyl salicylic acid include dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henycosyl, docosyl, tricosyl, Examples thereof include a tetracosyl group, a pentacosyl group, a hexacosyl group, a heptacosyl group, an octacosyl group, a nonacosyl group and a triacontyl group. Of these, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group and an octadecyl group are preferred.

The content of the component (1) in the lubricating oil composition for a diesel engine of the present invention is 0.1% by mass in terms of alkaline earth metal concentration based on the total amount of the lubricating oil composition.
Or more, preferably 0.15% by mass or more;
It is at most 5% by mass, preferably at most 2% by mass. When the content of the component (1) is less than 0.1% by mass in terms of the alkaline earth metal concentration based on the total amount of the lubricating oil composition, the oxidation stability is poor, which is not preferable. If the amount exceeds 2.5% by mass in terms of alkaline earth metal concentration based on the total amount of the lubricating oil composition, heat resistance and abrasion resistance are inferior.

The component (2) in the present invention is defined as (a) a total base number determined by a perchloric acid method of more than 220 mgKOH / g,
An alkaline earth metal salicylate of 400 mg KOH / g or less and / or (b) an alkaline earth metal sulfonate having a total base number of 20 to 200 mg KOH / g by a perchloric acid method.

The alkaline earth metal salicylate having a total base number by the perchloric acid method of the present invention of more than 220 mgKOH / g and not more than 400 mgKOH / g (hereinafter referred to as component (2) (a)) is perchloric acid. The total base number by the method is 220 mg KOH / g or more, preferably 230 mg KO
It is important that it is not less than H / g and not more than 400 mgKOH / g, preferably not more than 350 mgKOH / g. Component (2) (a) having a total base number of 220 mg KOH
/ G or less is not preferred because sufficient abrasion resistance cannot be obtained, and the total base number is 400 mg KO
If it exceeds H / g, heat resistance and oxidative stability decrease, such being undesirable.

The metal ratio of component (2) (a) is more than 3.5, preferably not less than 3.7 and not more than 15, preferably not more than 10. Ingredient (2)
By setting the metal ratio of (a) to 3.5 or more, sufficient wear resistance can be obtained, and by setting the metal ratio to 15 or less, good heat resistance and oxidation stability can be obtained. Each of them is preferable.

The component (2) (a) includes, among the alkaline earth metal salicylates described in the description of the component (1), a carbonate overbased (ultrabasic) salicylate and a borate overbased ( Ultrabasic) salicylates can be used.

The alkaline earth metal sulfonate (hereinafter referred to as component (2) (b)) in the present invention has a total base number of at least 20 mg KOH / g, preferably 8 by the perchloric acid method.
0 mgKOH / g or more, and 200 mgKOH / g
g or less, preferably 170 mg KOH / g or less. Component (2) (b) has a total base number of 20 m
When the amount is less than gKOH / g, the required addition amount increases,
Oxidation stability and abrasion resistance are unfavorably reduced, and when the total base number exceeds 200 mgKOH / g, oxidization stability is reduced and a precipitate may be formed due to interaction with other additives. Therefore, it is not preferable.

Examples of the alkaline earth metal in the component (2) (b) include calcium, magnesium and barium. Of these, calcium and magnesium are particularly preferred. Specific examples of the components (2) and (b) include so-called basic sulfonates, carbonate overbased (ultrabasic) sulfonates, and borate overbased (ultrabasic) sulfonates. In addition, component (2)
The production method of (b) is not particularly limited. Specifically, for example, a neutral (normal salt) alkaline earth metal sulfonate and an excess alkaline earth metal salt or base are heated in the presence of water. So-called basic alkaline earth metal sulfonate obtained by reacting a neutral alkaline earth metal sulfonate with an alkaline earth metal base in the presence of carbon dioxide gas, so-called carbonate overbased ( Ultrabasic) alkaline earth metal sulfonates; neutral alkaline earth metal sulfonates are reacted with alkaline earth metal bases and boric acid compounds such as boric acid or boric anhydride, or carbonate overbased (superbase) Produced by reacting an alkaline earth metal sulfonate with a boric acid compound such as boric acid or boric anhydride;
So-called borate overbased (ultrabasic) sulfonates;
And mixtures thereof.

The neutral (normal salt) alkaline earth metal sulfonate mentioned here is obtained by, for example, sulfonating an alkyl aromatic having a molecular weight of 300 to 1500, preferably 400 to 700 with fuming sulfuric acid or sulfuric anhydride to obtain an alkyl aromatic sulfonic acid. And then converted to an alkaline earth metal salt. Neutral (normal salt) of alkyl aromatic sulfonic acid
As a method of converting to an alkaline earth metal sulfonate, there are a method of directly converting to a metal salt, and a metathesis method of once converting to a sodium salt and then reacting with a target alkaline earth metal compound. Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid.

As the petroleum sulfonic acid used herein, there are generally used those obtained by sulfonating an alkyl aromatic in a lubricating oil fraction of a mineral oil and so-called mahoganic acid which is a by-product of white oil production.

As the synthetic sulfonic acid, for example, an alkylbenzene having a linear or branched alkyl group, which is obtained as a by-product from an alkylbenzene production plant used as a raw material of a detergent or obtained by alkylating a polyolefin to benzene. Or sulfonated alkylnaphthalene such as dinonylnaphthalene.

Carbonate overbased (ultrabasic) sulfonates are those in which the alkaline earth metal neutral salt of sulfonic acid is overbased by an alkaline earth metal carbonate, and when present in oil, The alkaline earth metal carbonate has a dispersion structure in which the alkaline earth metal salt of sulfonic acid is dispersed in the oil. Borate overbased (ultrabasic) sulfonates using neutral alkaline earth metal sulfonates as raw materials are those obtained by overbasing alkaline earth metal neutral salts of sulfonic acids with alkaline earth metal borates. And when present in the oil, has a dispersion structure in which the alkaline earth metal borate is dispersed in the oil by the alkaline earth metal salt of sulfonic acid. Also carbonate overbased (ultrabasic)
Borate overbased (ultrabasic) sulfonates made from alkaline earth metal sulfonates are used in which the alkaline earth metal neutral salt of sulfonic acid is overbased by alkaline earth metal carbonate and alkaline earth metal borate. When present in oil, a dispersion structure in which a mixture of an alkaline earth metal carbonate and an alkaline earth metal borate is dispersed in an oil by an alkaline earth metal sulfonic acid. Having.

The content of the component (2) in the lubricating oil composition for a diesel engine of the present invention is 0.01% by mass or more, preferably 0.1% by mass, in terms of alkaline earth metal concentration, based on the total amount of the lubricating oil composition. Not less than 02% by mass and 1
% By mass, preferably 0.8% by mass or less. When the content of the component (2) is less than 0.01% by mass in terms of the concentration of the alkaline earth metal based on the total amount of the lubricating oil composition, the cleanliness and abrasion resistance are inferior. ) Is based on the total amount of the lubricating oil composition,
If the concentration exceeds 1% by mass in terms of alkaline earth metal concentration, heat resistance and oxidation stability are inferior.

The lubricating oil composition for a diesel engine of the present invention has sufficient abrasion resistance, cleanliness, heat resistance and oxidative stability even with the components (1) and (2) alone, but further has a specific total base number. By adding a specific amount of an alkaline earth metal phenate having the following, the high-temperature detergency, abrasion resistance and anti-seizure performance, particularly anti-seizure performance, can be further improved.

The alkaline earth metal phenate (hereinafter referred to as component (3)) in the present invention has a total base number of at least 100 mgKOH / g, preferably 200 mK, by the perchloric acid method.
It is important that it is not less than gKOH / g and not more than 450 mgKOH / g, preferably not more than 350 mgKOH / g. If the total base number is less than 100 mgKOH / g, the required amount of addition is large, so that the lubricating oil contains a large amount of alkylphenols, which are the soap-based components of the phenate produced by the neutralization reaction, and is oxidatively stable. Is unfavorable due to the reduced baseability, and the total base number is 450 m
If it exceeds gKOH / g, the oxidation stability of the phenate itself is inferior, the hydrolysis stability is poor, and sludge is easily formed, which is not preferable.

Examples of the alkaline earth metal include calcium, magnesium and barium, of which calcium and magnesium are particularly preferred. Specific examples of the component (3) include a so-called basic phenate,
Carbonate overbased (ultrabasic) phenates and borate overbased (ultrabasic) phenates.

The method for producing the component (3) is not particularly limited. Specifically, for example, a linear or branched alkyl group having 6 to 50 carbon atoms, preferably 12 to 40 carbon atoms, may be used.
By reacting an alkylphenol having two amino acids or a Mannich reaction product of an alkylphenol with formaldehyde in the presence or absence of elemental sulfur with an alkaline earth metal base (such as an oxide or hydroxide of an alkaline earth metal); Obtained by heating a so-called neutral (normal salt) alkaline earth metal phenate and an excess of an alkaline earth metal salt or base in the presence of water,
So-called basic alkaline earth metal basic phenates; so-called carbonate overbased (ultrabasic) obtained by reacting a neutral alkaline earth metal phenate with an alkaline earth metal base in the presence of carbon dioxide gas Alkaline earth metal phenates; reaction of neutral alkaline earth metal phenates with alkaline earth metal bases and boric acid compounds such as boric acid or boric anhydride, or carbonate overbased (ultrabasic) alkaline earths So-called borate overbased (ultrabasic) phenates produced by reacting a metal-like phenate with a boric acid compound such as boric acid or boric anhydride; and mixtures thereof.

The carbonate overbased (ultrabasic) phenate is an alkaline earth metal neutral salt of an alkylphenol overbased with an alkaline earth metal carbonate,
When present in the oil, it has a dispersion structure in which the alkaline earth metal carbonate is dispersed in the oil by the alkaline earth metal salt of the alkylphenol. Borate overbased (ultrabasic) phenates made from neutral alkaline earth metal phenates are obtained by overbasing alkaline earth metal neutral salts of alkylphenols with alkaline earth metal borates. Yes, when present in an oil, it has a dispersion structure in which the alkaline earth metal borate is dispersed in the oil by an alkaline earth metal salt of an alkylphenol. Further, borate overbased (ultrabasic) phenate made from carbonate overbased (ultrabasic) alkaline earth metal phenate is an alkaline earth metal neutral salt of an alkyl phenol and an alkaline earth metal carbonate. It has been overbased with alkaline earth metal borates and, when present in the oil, a mixture of alkaline earth metal carbonate and alkaline earth metal borate forms an alkaline earth metal salt of an alkylphenol. Has a dispersion structure dispersed in oil.

Specific examples of the alkyl group of the alkylphenol include a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group and an octadecyl group. , Nonadecyl group,
Icosyl group, henycosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octakosyl group, nonacosyl group,
Triacontyl group, hentriacontyl group, dotriacontyl group, tritriacontyl group, tetratriacontyl group, pentatriacontyl group, hexatriacontyl group, heptatriacontyl group, octatriacontyl group, nonatriacontyl group , Tetracontyl, hentetracontyl, dotetracontyl, tritetracontyl, tetratetracontyl, pentatetracontyl, hexatetracontyl, heptatetracontyl, octatetracontyl, nonate Tracontyl and pentacontyl groups, among which dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henycosyl, docosyl, tricosyl Tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, hentriacontyl group, dotriacontyl group, tritriacontyl group,
Preferred are a tetratriacontyl group, a pentatriacontyl group, a hexatriacontyl group, a heptatriacontyl group, an octatriacontyl group, a nonatriacontyl group and a tetracontyl group.

The content of the component (3) in the lubricating oil composition for a diesel engine of the present invention is 0.05% by mass or more, preferably 0.1% by mass, in terms of alkaline earth metal concentration, based on the total amount of the lubricating oil composition. It is desirably 1% by mass or more and 2% by mass or less, preferably 1.5% by mass or less. By setting the content of the component (3) to 0.05% by mass or more in terms of alkaline earth metal concentration based on the total amount of the lubricating oil composition, sufficient heat resistance can be obtained, and the component (3) Is preferably 1.5% by mass or less in terms of alkaline earth metal concentration based on the total amount of the lubricating oil composition, since thereby sufficient oxidation stability and cleanability can be obtained, which is preferable.

The preferred content of component (1), component (2) and, if desired, component (3) in the lubricating oil composition for a diesel engine of the present invention depends on the quality of the fuel used in the diesel engine, especially sulfur. The total content of the components (1), (2) and, if desired, the component (3) is 0.2% in terms of alkaline earth metal concentration based on the total amount of the lubricating oil composition. % By mass or more, preferably 0.3% by mass or more, and 6% by mass
Or less, preferably 4% by mass or less.
By setting the total content to 0.2% by mass or more in terms of alkaline earth metal concentration based on the total amount of the lubricating oil composition, it is possible to prevent acid corrosion wear and carbon adhesion to cylinders and pistons. Further, by setting the total content to 6% by mass or less in terms of alkaline earth metal concentration based on the total amount of the lubricating oil composition, a cylinder head or a piston head of a product produced by combustion of a metal component contained in the lubricating oil is obtained. Can be avoided.

The lubricating oil composition for a diesel engine of the present invention has sufficient detergency only with the component (1), the component (2) and, if desired, the component (3), and further contains an alkenyl succinimide. By doing so, the cleanliness at high temperatures can be further improved.

As the alkenyl succinimide used in the present invention, a monoimide represented by the following general formula (1), a bisimide represented by the following general formula (2), or a imide modified with a carboxylic acid or a boron compound is used. What was done. The carboxylic acids here include formic acid, acetic acid,
1 to 1 carbon atoms such as propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, and heptadecanoic acid 18 carboxylic acids, preferably carboxylic acid having 2 to 7 carbon atoms, such as acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid and heptanoic acid. Examples of the boron compound include boric acid, boric anhydride, boron halide, boric ester, boric amide, and boron oxide.

[0042]

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[0043]

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In the formula, R ¹ , R ² and R ³ may be the same or different and have a number average molecular weight of 500 to 5000, preferably 900 to 3500, an alkyl or alkenyl group, preferably a polyalkenyl such as a polybutenyl group. And a and b each independently represent an integer of 2 to 5, preferably 3 to 5 for a group or an ethylene-propylene copolymer group. Monoimides and bisimides can be obtained by reacting polyalkenyl succinic acids with polyamines. Examples of the polyamine mentioned here include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and the like.

When the alkenyl succinimide is added to the lubricating oil composition for a diesel engine of the present invention, the content of the alkenyl succinimide is 0.005% by mass or more, preferably 0% by mass, based on the total amount of the lubricating oil composition. It is desirably 0.01% by mass or more and 0.2% by mass or less, preferably 0.1% by mass or less.

The lubricating oil composition for a diesel engine according to the present invention has sufficient rust inhibitory performance by only the component (1), the component (2) and, if desired, the component (3), but further comprises an alkenyl succinate or sorbitan. By containing an ester such as an alkyl ester and / or a polyether, rust prevention performance can be further enhanced.

As the alkenyl succinic ester used herein, maleic anhydride has a number average molecular weight of 500 to 200.
Alkenyl succinic acid synthesized by reacting a polyolefin of 0, for example, polybutenyl succinic acid synthesized by reacting a polybutene, and a polyhydric alcohol such as pentaerythritol, and an oligomer such as ethylene oxide and propylene oxide. Esters obtained by reacting polyalkylene glycols, and there are mono- or di-substituted esters. Examples of the sorbitan alkyl ester include those represented by the following general formula (3).

[0048]

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In the formula, R ⁴ is an alkyl group having 12 to 18 carbon atoms, and specific examples include dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl.

Specific examples of the polyether include compounds containing a polyalkylene glycol unit in the molecular structure. Specific examples thereof include polyoxyethylene glycol monoalkyl ether, polyoxyethylene glycol monoaryl ether, and polyoxyethylene glycol. Examples include a polyoxypropylene block copolymer, a polyoxyalkylene adduct of alkylenediamine, and a polyoxyethylene sorbitan alkyl ester. Examples of the polyoxyethylene glycol monoalkyl ether referred to herein include those represented by the following general formula (4).

[0051]

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In the formula, R ⁵ is an alkyl group having 12 to 18 carbon atoms, and specific examples include dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl. 2-10,
Preferably it is an integer of 3 to 7. Examples of the polyoxyethylene glycol monoaryl ether include those represented by the following general formula (5).

[0053]

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In the formula, R ⁶ is an alkyl group having 9 to 12 carbon atoms, and specific examples thereof include a nonyl group, a decyl group, an undecyl group and a dodecyl group, and d is 2 to 10, preferably 3 to 7 Is an integer. Examples of the polyoxyethylene-polyoxypropylene block copolymer include those represented by the following general formula (6).

[0055]

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In the formula, e is an integer of 2 to 10, and f is 5 to 5
0, preferably an integer of 15 to 40, g represents an integer of 2 to 10, and e + f + g is 20 to 70, preferably 15 to 60. Examples of the polyoxyalkylene adduct of alkylene diamine include those represented by the following general formula (7).

[0057]

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In the formula, R ⁷ is an alkylene group having 2 or 3 carbon atoms, such as an ethylene group or a propylene group, and particularly preferably an ethylene group. H, i, j,
k, l, m, n and p may be the same or different, and represent an integer of 10 to 20. Also, h +
i, j + k, l + m and n + p are each 30 or less. The polyoxyalkylene adduct of alkylenediamine has a number average molecular weight of 1,000 to 6,000, preferably 15 to 5,000.
Desirably, it is from 00 to 4000. Examples of the polyoxyethylene sorbitan alkyl ester include those represented by the following general formula (8).

[0059]

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In the formula, R ⁸ is an alkyl group having 12 to 18 carbon atoms, and specific examples include dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl. In addition, q, r and s each represent an integer of 2 to 20.

When the ester and / or polyether is added to the lubricating oil composition for a diesel engine of the present invention, the content thereof is 0.0
It is desirably 5% by mass or more, preferably 0.1% by mass or more, and 1% by mass or less, preferably 0.5% by mass or less.

The lubricating oil composition for a diesel engine of the present invention has sufficient oxidation stability and abrasion resistance even when only the component (1), the component (2) and, if desired, the component (3) are used. Oxidation stability and abrasion resistance can be further enhanced by containing zinc hydrocarbyl dithiophosphate. The zinc dihydrocarbyl dithiophosphate referred to in the present invention is a compound represented by the following general formula (9).

[0063]

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In the formula, R ⁹ , R ¹⁰ , R ¹¹ and R ¹² independently represent a hydrocarbon group having 1 to 18 carbon atoms. Specific examples of the hydrocarbon group represented by R ⁹ , R ¹⁰ , R ¹¹ and R ¹² include, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group,
Isobutyl, sec-butyl, tert-butyl, linear or branched pentyl, linear or branched hexyl, linear or branched heptyl, linear or branched octyl, Chain or branched nonyl, straight or branched decyl, straight or branched undecyl, straight or branched dodecyl, straight or branched tridecyl, straight or branched An alkyl group having 1 to 18 carbon atoms such as a tetradecyl group, a linear or branched pentadecyl group, a linear or branched hexadecyl group, a linear or branched heptadecyl group, a linear or branched octadecyl group;
Straight or branched butenyl, straight or branched pentenyl, straight or branched hexenyl, straight or branched heptenyl, straight or branched octenyl, straight or branched A nonenyl group, a straight or branched decenyl group, a straight or branched undecenyl group, a straight or branched dodecenyl group, a straight or branched tridecenyl group, a straight or branched tetradecenyl group, A chain or branched pentadecenyl group, a straight or branched hexadecenyl group,
A C 4-18 alkenyl group such as a linear or branched heptadecenyl group, a linear or branched octadecenyl group; a C 5-7 cycloalkyl group such as a cyclopentyl group, cyclohexyl group, cycloheptyl group; methyl Cyclopentyl group, dimethylcyclopentyl group (including all structural isomers), methylethylcyclopentyl group (including all structural isomers), diethylcyclopentyl group (including all structural isomers), methylcyclohexyl group, dimethylcyclohexyl group (Including all structural isomers), methylethylcyclohexyl group (including all structural isomers), diethylcyclohexyl group (including all structural isomers), methylcycloheptyl group, dimethylcycloheptyl group (including all structural isomers) Isomer), methylethylcycloheptyl group (including Alkylcycloalkyl groups having 6 to 11 carbon atoms such as diethylcycloheptyl group (including all structural isomers); aryl groups such as phenyl group and naphthyl group: tolyl group (all Xylyl group (including all structural isomers), ethylphenyl group (including all structural isomers), linear or branched propylphenyl group (including all structural isomers) A linear or branched butylphenyl group (including all structural isomers), a linear or branched pentylphenyl group (including all structural isomers), a linear or branched hexylphenyl group (all ), A linear or branched heptylphenyl group (including all structural isomers), a linear or branched octylphenyl group (including all structural isomers), a linear or branched branch (Including all structural isomers) nonylphenyl group, a linear or branched decylphenyl group (including all structural isomers),
Each alkylaryl group having 7 to 18 carbon atoms such as a linear or branched undecylphenyl group (including all structural isomers) and a linear or branched dodecylphenyl group (including all structural isomers) A benzyl group, a phenylethyl group,
Phenylpropyl group (including isomer of propyl group), phenylbutyl group (including isomer of butyl group), phenylpentyl group (including isomer of pentyl group), phenylhexyl group (including isomer of hexyl group) 7)
To 12 arylalkyl groups.

The above-mentioned alkyl group or alkenyl group may be a so-called primary alkyl group or alkenyl group in which the carbon atom at the portion bonded to oxygen is a primary carbon, and the carbon atom is secondary. Or a so-called secondary alkyl group or alkenyl group, or a tertiary alkyl or alkenyl group in which the carbon atom is tertiary.

Among these, in particular, R ⁹ , R ¹⁰ , R ¹¹
And the hydrocarbon group represented by R ^12, from the viewpoint of excellent friction-reducing properties and anti-wear properties, separately, a linear or branched, preferably an alkyl group having 1 to 18 carbon atoms.

In the present invention, an arbitrary mixing ratio of two or more zinc dihydrocarbyl dithiophosphates having different structures represented by the general formula (9) is used as the zinc dihydrocarbyl dithiophosphate. Of course you can.

Particularly preferable examples of the zinc dihydrocarbyl dithiophosphate include, for example, zinc diisopropyldithiophosphate, zinc diisobutyldithiophosphate, zinc di-sec-butyldithiophosphate, di-s
zinc ec-pentyldithiophosphate, zinc di-n-hexyldithiophosphate, zinc di-sec-hexyldithiophosphate, zinc di-n-octyldithiophosphate, zinc di-2-ethylhexyldithiophosphate, di-n-decyldithiophosphate Examples include zinc, zinc di-n-dodecyldithiophosphate, zinc diisotridecyldithiophosphate, and mixtures thereof.

When the zinc dihydrocarbyl dithiophosphate is added to the lubricating oil composition for a diesel engine of the present invention, the content is 0.01% by mass or more in terms of phosphorus concentration based on the total amount of the lubricating oil composition. Preferably it is 0.02% by mass or more and 0.2% by mass or less, preferably 0.1% by mass or less.
It is desirably 15% by mass or less.

The lubricating oil composition for a diesel engine of the present invention has sufficient oxidation stability and abrasion resistance by only the component (1), the component (2) and, if desired, the component (3). 0.005 succinimide in terms of nitrogen concentration based on the total amount of the lubricating oil composition
０．２0.2% by mass, ester and / or polyether in an amount of 0.05-1% by mass based on the total amount of the lubricating oil composition,
Further, by containing 0.01 to 0.2% by mass of zinc dihydrocarbyl dithiophosphate in terms of phosphorus concentration, high-temperature detergency, rust prevention, oxidation stability, and abrasion resistance can be further enhanced.

The lubricating oil composition for a diesel engine of the present invention has excellent performance as a diesel engine oil by itself, and in particular, its abrasion resistance is maintained for a long period of time. Known lubricating oil additives other than those described above may be used alone or in combination with the lubricating oil composition for a diesel engine of the present invention. Specific examples of known lubricating oil additives that can be blended include, for example, additives effective in imparting diesel engine oil performance, such as antioxidants, viscosity index improvers, antiwear agents, and friction reducing agents. Is mentioned.

Examples of the antioxidant include phenol-based and aromatic amine-based antioxidants, and specific examples thereof include 4,4-methylenebis (2,6-di-tert-phenol and 4,4-bis ( 2,6-di-tert-butylphenol), 4,4-bis (2-methyl 6-ter
t-butylphenol), 2,2-methylenebis (4-
Ethyl-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-α-dimethylamino-p-cresol, 2,6-di-tert-
Butyl (N, N-dimethylaminomethylphenol),
4,4-thiobis (3-methyl-6-tert-butylphenol), 2,2-thiobis (4-methyl-6-t
tert-butylphenol), bis (3-methyl-4-)
Hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, 2,2-dithio-diethylenebis [3 (3,5-di-tert-butyl) -4-hydroxyphenol) propionate], tridecyl-3
-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3
-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and the like.

Further, specific examples of the aromatic amine antioxidant include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, dialkyldiphenylamine, and N, N-diphenyl-p-phenylenediamine. . These compounds described above can be used alone or as a mixture.

Specific examples of the viscosity index improver include polymethacrylate, polyisobutylene, ethylene-propylene copolymer, styrene-diene copolymer and the like. These compounds may be used alone if necessary. Of course, they can be mixed and blended.

As the antiwear agent, an organic phosphate ester,
Examples include organic phosphites, fatty acids, fatty acid esters, and the like. Examples of the friction reducing agent include molybdenum dithiophosphate and molybdenum thiocarbamate.

The lubricating oil composition for a diesel engine of the present invention can be preferably used as a lubricating oil for a land-based diesel engine and a marine diesel engine.

[0077]

EXAMPLES The contents of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The performance of the diesel engine oil used in the examples and comparative examples was evaluated by performance evaluation tests described below.

(Shell high-speed four-ball abrasion test) The load-bearing performance of the test oil was in accordance with ASTM D417-82 (shell high-speed four-ball abrasion test) at room temperature, 1800 rpm, for 30 minutes, with a load of 5 kgf. The wear scar diameter at each load and the load at the time of seizure were measured and evaluated. In addition, about the wear scar diameter, the measured value at the time of 50 kgf load was shown to the table | surface. As a tester, a new model high-speed four-sphere friction tester manufactured by Shinko Zoki Co., Ltd. was used.

(Hot Tube Test) The high temperature cleaning performance of the test oil was determined by the Komatsu Seisakusho type hot tube test “HT-20”.
1 ". Specifically, a soft glass tube (inner diameter 2 mm, outer diameter 4 mm, length 300 mm) was heated to a predetermined temperature (330 ° C.) with a pure aluminum burning block, and 0.31 mL / h of sample oil was added to the tube. Air volume 1
0 mL / min is fed continuously for 16 hours. After the test,
The tube is washed with petroleum ether and the score is determined from the stain on the inner wall. The rating was 10 points for colorless and transparent (no stain) and 0 points for black and opaque.

(Panel Caulking Test) The heat resistance of the test oil was measured using a quadruple apparatus (type 25B19-4) manufactured by Meitec. Specifically, a test piece manufactured by Nippon Test Panel Kogyo Co., Ltd. (aluminum plate sandblasted, 3.4 mm, 6.1 × 37.1 × 87.6 mm)
The test was conducted at a panel temperature of 325 ° C. and an oil temperature of 100 ° C. for 24 hours in a cycle of a splash time of 15 seconds and a stop time of 45 seconds. After the test was completed, the panel was washed with petroleum ether, deoiled, dried, and the adhered caulk was weighed.
The weight was evaluated.

(Oxidation Stability Test) The oxidation stability of the test oil was determined by examining the oxidation stability test of a lubricating oil for an internal combustion engine (Indiana).
Stirring Oxidation Test, J
IS K 2514-3.1, hereinafter abbreviated as ISOT)
The test was carried out in accordance with 250 mL of sample oil, a copper plate (thickness 0.5 mm, 25.5 × 56.0 mm) and an iron plate (thickness 0.6 mm, 25.0 × 134.8 mm) as a catalyst, and a temperature of 165. After testing at 0.5 ° C. for 72 hours, the rate of increase in viscosity and the rate of residual base number of the test oil were measured and evaluated.

(Examples 1 to 8) Tables 1 and 2 show the performance evaluation results of the diesel engine oils of Examples 1 to 8 whose compositions are shown in Tables 1 and 2.

[0083]

[Table 1]

[0084]

[Table 2] (Continuation of Table 1)

As can be seen from Tables 1 and 2, the diesel engine oils of Examples 1 to 8 not only have excellent performance in the evaluation of wear resistance in the shell high-speed four-ball wear test, but also have high heat resistance in the panel coking test. It can be seen that they have excellent performance in any of the evaluations, such as heat resistance, high-temperature detergency in a hot tube test, and oxidation stability in an oxidation stability test (ISOT). That is, the diesel engine oil composition of the present invention is not only excellent in abrasion resistance performance, but also excellent in oxidative stability, heat resistance and cleanliness, and has a high load and a diesel engine which is continuously operated for a long time, It can be operated in a stable state.
Such effects of the present invention can be realized for the first time by a synergistic effect developed by combining each alkaline earth metal-based detergent having a specific total base number at a specific ratio. This will be described below with reference to a comparative example.

Comparative Example 1 A lubricating oil composition was prepared in the same manner as in Example 1 except that the component (1) was not added, and a high-speed four-ball shell abrasion test was performed on the lubricating oil composition. At this time, in order to make the kinematic viscosity of the composition equal to that in Example 1, the mixing ratio of the mineral oil A and the mineral oil B was adjusted. Value 230 (metal ratio 3.
Adjusted with the amount of overbased calcium salicylate in 8). The results are shown in Tables 3 and 4. The abrasion resistance of the test oil of Example 1 was found to be significantly lower than the abrasion resistance of the test oil of Example 1 with respect to the abrasion resistance of the test oil in the shell high-speed four-ball abrasion test, with a wear scar diameter of 1.88 mm and a seizure load of 65 kgf. In addition, the heat resistance in the panel coking test, the high-temperature cleanliness in the hot tube test, and the oxidation stability (viscosity increase suppression power and base number retention) as observed in the oxidation stability test (ISOT) were the same as those of Example 1. Lower than the performance of the test oil, especially
It can be seen that high-temperature detergency and oxidation stability are significantly lower.

(Comparative Example 2) A lubricating oil composition was prepared in the same manner as in Examples 1 and 2 except that the component (2) was not added, and a shell high-speed four-ball wear test was performed on the lubricating oil composition. At this time, in order to make the kinematic viscosity of the composition equal to those of Examples 1 and 2, the mixing ratio of mineral oil A and mineral oil B is adjusted, and the total base number of the composition is made equal to those of Examples 1 and 2. Therefore, the amount was adjusted with the amount of overbased calcium salicylate having a total base number of 170 (metal ratio: 3.0). The results are shown in Tables 3 and 4. The wear resistance performance of the shell high-speed four-ball wear test was 0.52 mm for wear scar diameter and 65 kg for seizure load.
It can be seen that f is lower than the wear resistance of the test oils of Example 1 and Example 2. In addition, the heat resistance in the panel coking test, the high-temperature cleanliness in the hot tube test, and the oxidative stability (viscosity increase suppressing power and base number maintaining property) as seen in the oxidative stability test (ISOT) were all the same as those in Examples 1 and 2. It can be seen that the performance of the test oil of Example 2 is lower than that of the test oil, and particularly the high-temperature cleanability and heat resistance are significantly lower.

Comparative Example 3 A lubricating oil composition was prepared in the same manner as in Example 3 except that the component (1) was not added, and subjected to a shell high-speed four-ball wear test. At this time, in order to make the kinematic viscosity of the composition equal to that of Example 3, the mixing ratio of the mineral oil A and the mineral oil B was adjusted. 280 (metal ratio 8.
Adjusted with the amount of overbased calcium salicylate in 0). The results are shown in Tables 3 and 4. The abrasion resistance of the test oil of Example 3 was found to be significantly lower than the abrasion resistance of the test oil of Example 3 as to the abrasion resistance in the shell high-speed four-ball abrasion test, in which the wear scar diameter was as large as 0.58 mm and the seizure load was as low as 70 kgf. That is, one of the features of the present invention, the excellent wear resistance, is that, as a metal-based detergent, an overbased calcium salicylate having a total base number of 280 (metal ratio of 8.0) and an overbased calcium salicylate having a base number of 260 are used. It is not found in diesel engine oil combined with phenate and has a total base number of 170 as a metallic detergent.
It can be seen that the expression occurs for the first time in a diesel engine oil using an overbased calcium salicylate (metal ratio: 3.0).

Comparative Example 4 A lubricating oil composition was prepared in the same manner as in Examples 3, 4, 5, and 6 except that the component (2) was not added, and a high-speed four-ball shell abrasion test was performed on the lubricating oil composition. At this time, in order to make the kinematic viscosity of the composition equal to that of Examples 3, 4, 5 and 6, the blending ratio of mineral oil A and mineral oil B was adjusted, and the total base number of the composition was adjusted to that of Examples 3, 4, and 5. In order to make the same as 5 and 6, the total base number is 170 (metal ratio is 3.0)
Of overbased calcium salicylate. The results are shown in Tables 3 and 4. The wear resistance of the shell as measured by the high-speed four-ball wear test was as large as 1.98 mm.
The seizure load was as low as 70 kgf, which was significantly lower than the abrasion resistance of the test oils of Examples 3, 4, 5, and 6, and the heat resistance as measured by the oxidation stability test (ISOT) and the panel coking test. It turns out that sex is also lower. That is, the total base number 230 (metal ratio 3.
8) By adding overbased calcium salicylate of 253 (metal ratio of 5.4) and 280 (metal ratio of 8.0) or overbased calcium sulfonate of total base number 150, abrasion resistance, heat resistance, It can be seen that high-temperature detergency and oxidation stability can be improved, and in particular, abrasion resistance can be significantly improved.

(Comparative Example 5) A test in which the lubricating oil composition of Comparative Example 4 which was the same as Example 4 except that the component (2) was not added was deteriorated by performing the above-mentioned ISOT test. The oil was subjected to a shell high-speed four-ball wear test. The results are shown in Tables 3 and 4. The abrasion resistance in the shell high-speed four-ball abrasion test shows that the abrasion resistance of the test oil of Example 7 which is an ISOT test oil of the same lubricating oil composition as in Example 4 was significantly improved in both the wear scar diameter and the seizure load. You can see it falls below. Also, regarding the comparison of the wear resistance performance before and after the ISOT test, in Example 7, the wear scar diameter increased by 6.9% and the seizure load decreased by 6.2% with respect to Example 4, whereas the comparative example In No. 5, the wear scar diameter was 15.
8% increase, the seizure load has decreased by 21.4%,
This shows that the wear resistance of the oxidized and deteriorated test oil has a large decrease rate, and the heat resistance and the high temperature cleanliness show the same tendency. In other words, it can be seen that the test oil of Comparative Example 4 is significantly lower than the performance of the test oil of Example 4 in terms of wear resistance, heat resistance, and durability of high-temperature cleanliness.

Comparative Example 6 A lubricating oil composition was prepared in the same manner as in Example 6 except that the component (1) was not added, and subjected to a shell high-speed four-ball wear test. At this time, in order to make the kinematic viscosity of the composition equal to that in Example 6, the mixing ratio of the mineral oil A and the mineral oil B was adjusted, and in order to make the total base number of the composition equal to that in Example 6, all bases were used. 253 (metal ratio 5.
Adjusted with the amount of overbased calcium salicylate in 4). The results are shown in Tables 3 and 4. It can be seen that the abrasion resistance performance in the shell high-speed four-ball abrasion test is significantly lower than the abrasion resistance performance of the test oil of Example 6 in both the wear scar diameter and the seizure load. In addition, the heat resistance, high-temperature detergency, and oxidation stability also show a tendency to decrease in performance. That is, one of the features of the present invention, such as excellent abrasion resistance performance, is that as a metal-based detergent, an overbased calcium salicylate having a total base number of 253 (metal ratio of 5.4) and an overbased calcium salicylate having a base number of 260 are used. It is not recognized in the diesel engine oil used in combination with calcium phenate, and it can be seen that it appears for the first time in a diesel engine oil using an overbased calcium salicylate having a total base number of 170 (metal ratio: 3.0) as a metal-based detergent.

(Comparative Example 7) A lubricating oil composition was prepared in the same manner as in Example 8 except that the component (2) was not added. An ISOT was performed for panel coking test and evaluation of oxidation stability. At this time, in order to make the kinematic viscosity of the composition equal to that of Example 8, the blending ratio of mineral oil A and mineral oil B was adjusted. The amount was adjusted with the amount of overbased calcium salicylate having a value of 170 (metal ratio: 3.0). Table 3 shows the results
And Table 4. It can be seen that the hot oil test, panel caulking test, and high-temperature cleanliness, heat resistance, and oxidative stability as measured by ISOT are all lower than the test oil of Example 8. That is, even in a system to which succinimide, a rust inhibitor and ZDTP are added, the total base number 2
By adding an overbased calcium salicylate of 30 (metal ratio of 3.8), the effect of improving various properties such as high-temperature detergency, oxidation stability and heat resistance, which are features of the present invention, is exhibited without any impairment. You can see that.

As can be seen from the comparative examples, in the present invention, it is important to combine each alkaline earth metal-based detergent having a specific total base number in a specific ratio, and it is important to have such a constitution. Alone, a synergistic effect is exhibited, and it is possible to obtain a lubricating oil composition for a diesel engine having excellent wear resistance, heat resistance, and high-temperature detergency, and is excellent when the added amount is out of the range of the present invention. A lubricating oil composition for a diesel engine cannot be obtained.

[0094]

[Table 3]

[0095]

[Table 4] (Continuation of Table 3)

[0096]

Industrial Applicability The lubricating oil composition for a diesel engine of the present invention has a high abrasion resistance due to a synergistic effect exhibited by combining each alkaline earth metal-based detergent having a specific total base number in a specific ratio. Heat resistance and cleanliness are greatly improved, and a diesel engine that is continuously operated for a long time under a high load can be operated in a stable state.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10N 30:04 30:06 30:08 30:10 40:25

Claims (2)

[Claims] A kinematic viscosity at 100 ° C. of 5 to 40 mm
² / s lubricating base oil, based on the total amount of the composition, (1)
The total base number by the perchloric acid method is 60 to 220 mgKOH /
g of alkaline earth metal salicylate in terms of alkaline earth metal concentration of 0.1 to 2.5% by mass and (2)
(A) The total base number by the perchloric acid method is 220 mgKOH /
g and an alkaline earth metal salicylate of 400 mg KOH / g or less and / or (b) an alkaline earth metal sulfonate having a total base number of 20 to 200 mg KOH / g by a perchloric acid method in terms of an alkaline earth metal concentration. A lubricating oil composition for a diesel engine comprising 0.01 to 1% by mass. And (3) converting an alkaline earth metal phenate having a total base number of 100 to 450 mgKOH / g by the perchloric acid method to 0.05 to 0.05 mg in terms of alkaline earth metal concentration.
The lubricating oil composition for a diesel engine according to claim 1, comprising 2% by mass.