WO2003033629A1

WO2003033629A1 - Lubricating oil composition for internal combustion engine

Info

Publication number: WO2003033629A1
Application number: PCT/JP2002/010679
Authority: WO
Inventors: Kazuhiro Yagishita; Jinichi Igarashi; Takeo Koizumi
Original assignee: Nippon Oil Corporation
Priority date: 2001-10-12
Filing date: 2002-10-15
Publication date: 2003-04-24
Also published as: US20040242434A1; EP1439217A1; EP1439217A4; EP1439217B1

Abstract

A lubricating oil composition for internal combustion engines which comprises a lube base oil and, incorporated therein, (A) 0.01 to 0.2 wt.% phosphoric triester represented by the general formula (1) in terms of phosphorus amount, (B) 0.01 to 0.3 wt.% succinimide and/or derivative thereof in terms of nitrogen amount, (C) 0.05 to 1 wt.% alkali metal or alkaline earth metal detergent in terms of metallic-element amount, and (D) 0.01 to 3 wt.% phenolic antioxidant and/or amine antioxidant. It is excellent in antiwear properties, retention of base number, high-temperature detergency, and low-friction characteristics. O=P(OR1)3 (1) (In the formula, R1 represents a C1-30 hydrocarbon group.)

Description

Description Lubricating oil composition for internal combustion engine

[Technical field]

The present invention relates to a lubricating oil composition for an internal combustion engine, and more particularly, to a lubricating oil composition for an internal combustion engine having excellent antiwear properties, base number retention, high-temperature detergency, and low friction.

[Background technology]

Zinc dialkyldithiophosphate (ZDTP) has excellent antiwear properties and antioxidant properties as a peroxide decomposer, and is an indispensable additive for all types of lubricants, including lubricants for internal combustion engines. Has been used as

On the other hand, lubricating oil compositions which do not use ZDTP are known as lubricating oil compositions containing a dialkyldithiol zinc rubinate or a sulfur-based additive in order to maintain its wear-preventing performance (see, for example, JP-A-2-704, JP-A-62-253691, JP-T-62-501572, JP-T-62_501917, JP-T-63-304095 Japanese Patent Application Laid-Open Publication No. Hei. The lubricating oils described in these publications contain a large amount of sulfur as well as the lubricating oil containing ZDTP. Such lubricating oils generally have poor oxidation stability, and the consumption (deterioration) of the base number tends to be accelerated. The present inventors have focused on the base number retention of lubricating oils for internal combustion engines that contain a large amount of sulfur, and as a result of intensive studies, found that sulfur-containing compounds such as ZDTP are themselves oxidized or thermally decomposed. Then, sulfuric acid is generated in the lubricating oil, thereby significantly depleting the base number, shortening the life of the lubricating oil, and significantly deteriorating cleanliness, especially when used at high temperatures, and having low friction. Turned out to be inferior.

In particular, deep desulfurized gas oil with sulfur content reduced to 50 mass ppm or less for diesel engines equipped with DPF (diesel particulate fill), kerosene with sulfur content of 50 mass ppm or less, gasoline , LPG, natural gas, or When hydrogen, dimethyl ether, alcohol, etc., which do not substantially contain sulfur, is used as fuel, the amount of sulfuric acid due to the sulfur in the fuel is reduced in engine lubricating oil. Generally, the service life of lubricating oil is longer than when high-sulfur fuel is used. However, in order to further extend the drainage of the engine oil and further enhance the high-temperature cleanliness of the oil, it is not sufficient to use only the low-sulfur-containing fuel as described above. It has become necessary to study additives that can replace antioxidants and antioxidants. In particular, gas engines generally have high combustion temperatures and lubricating oils are exposed to high temperatures and NOx, so it is necessary to improve oxidation stability and high-temperature cleanliness. Furthermore, in order to maintain the performance of exhaust gas purification equipment such as DPF, three-way catalysts, oxidation catalysts, NOx storage reduction catalysts, and EGR, engine oils with low sulfur content are also desired.

Therefore, an object of the present invention is to maintain or further improve the anti-wear performance and anti-oxidation performance of conventionally used ZDTP and the like, and reduce the sulfur content in engine oil to reduce the deterioration of the oil. An object of the present invention is to provide a lubricating oil composition for an internal combustion engine, which is capable of suppressing the consumption of a base number and improving the long drain performance, and is also excellent in high-temperature detergency and low friction.

[Disclosure of the Invention]

The present inventors have conducted intensive studies to solve the above problems, and as a result, identified a specific phosphorus compound, a specific ashless dispersant, a specific metal detergent and a specific antioxidant in a lubricating base oil. It has been found that by containing a large amount, a lubricating oil that is excellent in antiwear properties, improves base number retention and can be used as a gang drain, and is also excellent in high-temperature cleanability and low friction properties can be obtained. The invention has been completed. That is, the present invention relates to a lubricant base oil comprising (A) a phosphoric acid triester represented by the general formula (1) in an amount of 0.01 to 0.2% by mass in terms of a phosphorus element, and (B) succinic acid. 0.1 to 0.3 mass% of imid and / or its derivative in terms of nitrogen element, (C) 0.05% in terms of metal element or alkaline earth metal-based cleaning agent To 1% by mass, and (D) a phenolic antioxidant and / or an amine antioxidant A lubricating oil composition for an internal combustion engine, characterized in that it contains 3% by mass.

0 = P (OR ¹ ) 3 (1)

(In the formula, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, which may be the same or different.) In the lubricating oil composition for an internal combustion engine of the present invention, Further, it is preferable that the alkaline earth metal-based detergent contains an alkaline earth metal or an alkaline earth metal salicylate-based detergent.

In the lubricating oil composition for an internal combustion engine according to the present invention, the alkali metal or alkaline earth metal salicylate-based detergent may have a valence of a metal element X a content of a metal element (mol) / a content of a soap group (mo). It is preferable to use an alkali metal or alkaline earth metal salicylate-based detergent having a metal ratio represented by l) of 3 or less.

In the lubricating oil composition for an internal combustion engine according to the present invention, the alkali metal or alkaline earth metal-based detergent comprises a valence of a metal element X a metal element content (mol) / a soap group content (mo) l) An alkali metal or alkaline earth metal salicylate detergent having a metal ratio of 1.5 or less and an alkali metal or alkaline earth metal salicylate detergent having a metal ratio of more than 1.5 Preferably, it is a mixture.

In the lubricating oil composition for an internal combustion engine according to the present invention, the alkali metal or alkaline earth metal-based detergent comprises a valence of a metal element X a metal element content (mol) / a soap group content (mo) l) A mixture of an alkali metal or alkaline earth metal salicylate detergent having a metal ratio of 1.5 or less and an alkali metal or alkaline earth metal sulfonate detergent. Preferably, there is.

The lubricating oil composition for an internal combustion engine of the present invention preferably further contains a sulfur-containing antiwear agent having a content of 0.1% by mass or less in terms of a sulfur element.

In the lubricating oil composition for an internal combustion engine of the present invention, it is preferable that the lubricating base oil has a total aromatic content of 3% by mass or less and a sulfur content of 50% by mass or less.

The lubricating oil composition for an internal combustion engine of the present invention is preferably used for an internal combustion engine using a fuel having a sulfur content of 50 mass ppm or less.

The lubricating oil composition for an internal combustion engine of the present invention is preferably used for a gas engine. No. The lubricating base oil in the lubricating oil composition for an internal combustion engine of the present invention may be a mineral oil-based lubricating oil, a synthetic oil-based lubricating oil, or a mixture of two or more lubricating oils selected from these at any mixing ratio. For example, one or more mineral oil-based lubricating oils, one or more synthetic oil-based lubricating oils, a mixed oil of one or more mineral oil-based lubricating oils and one or more synthetic oil-based lubricating oils, etc. Can be mentioned.

As the mineral oil-based lubricating oil, for example, a lubricating oil fraction obtained by distilling crude oil under normal pressure and reduced pressure is subjected to solvent removal, solvent extraction, hydrocracking, solvent removal, and contact removal. Oils such as paraffinic and naphthenic oils and normal paraffins, which are purified by appropriately combining one or more purification treatments such as hydrorefining, sulfuric acid washing, and clay treatment, can be used. In particular, use of advanced hydrocracking processes that can further reduce aromatics and sulfur content, and products manufactured using GTLW ax (gas' to 'liquid' wax) isomerization Is preferred.

The synthetic lubricating oil is not particularly limited, and may be, for example, polyolefin (eg, 1-octene oligomer, 1-decene oligomer, ethylene-propylene oligomer, etc.) or a hydride thereof, or isobutene oligomer. Or its hydride, isoparaffin, alkylbenzene, alkylnaphthylene, diester (for example, ditridecyl glulate, di2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, etc.), polyol ester (Eg, trimethylolpropane caprate, trimethylolprononperargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol perargonate, etc.), polyoxyalkyl Glycol, dialkyl diphenyl ether, and polyphenyl ether and the like can be used.

Lubricating oil The sulfur content in the oil is not particularly limited, but is preferably 500 ppm by mass or less, more preferably 50 ppm by mass or less, even more preferably 20 ppm by mass or less. , 10 mass ppm or less. If the lubricating oil base contains a large amount of sulfur, the base value of the composition can be maintained and the exhaust gas can be purified. It is not preferable because it has an adverse effect on the device.

The total aromatic content in the lubricating base oil is not particularly limited, but is preferably 15% by mass or less, more preferably 10% by mass or less, and still more preferably 3% by mass or less, and 2% by mass or less. Is particularly preferred. If the total aromatic content of the base oil exceeds 15% by mass, the base number retention and high-temperature detergency are poor, which is not preferable. In addition, the said total aromatic content means the content of the aromatic fraction (aromaticfracacton) measured according to ASTM D2549. Usually, this aromatic fraction includes, in addition to alkylbenzene and alkylnaphthalene, anthracene, phenanthrene and their alkylated compounds, compounds in which four or more benzene rings are condensed, or pyridines, quinolines, phenols, naphthols And compounds having a heteroaromatic such as a class.

The kinematic viscosity of the lubricating base oil at 100 ° C is not particularly limited.However, in order to excel in low-temperature viscosity characteristics and oil film formation at lubricating points, and to reduce the evaporation loss of the lubricating base oil, 1 to 2 Omm s, preferably 2 to 10 mm ² / s.

The viscosity index of the lubricating base oil is not particularly limited, but is preferably 80 or more, more preferably 100 or more, and particularly preferably 120 or more. The component (A) in the lubricating oil composition for an internal combustion engine of the present invention is a phosphoric triester represented by the following general formula (1).

0 2 P (OR ¹ ) 3 (1)

R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms. The three R ^{1 s} may be the same or different.

Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and an arylalkyl group.

The alkyl group may be linear or branched, and specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. , Nonyl group, decyl group, pendecyl group, dodecyl group, Examples include a lydecyl group, a tetradecyl group, a pendecyl group, a hexadecyl group, a heptanedecyl group and an octadecyl group.

The cycloalkyl group may have a substituent, and specific examples thereof include a cycloalkyl group having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group; Methylcyclopentyl group, dimethylcyclopentyl group, methylethylcyclopentyl group, getylcyclopentyl group, methylcyclohexyl group, dimethylcyclohexyl group, methylethylcyclohexyl group, getyl cyclohexyl group, methylcycloheptyl group, Alkylcycloalkyl groups having 6 to 11 carbon atoms (the substitution position of the alkyl group is also arbitrary) such as a dimethylcycloheptyl group, a methylethylcycloheptyl group, and a getylcycloheptyl group.

The alkenyl group may be linear or branched, and specific examples thereof include a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, C2-C30 alkenyl groups such as nonenyl, decenyl, benzyldecenyl, dodecenyl, tridecenyl, tetradecenyl, pendecenyl, hexadecenyl, heptanedecenyl, and octenyldecenyl; (The position of the double bond of these alkenyl groups is also arbitrary).

The aryl group may be substituted with an alkyl group. Examples of such an aryl group include, for example, a phenyl group and a naphthyl group having 6 to 18 carbon atoms such as a tolyl group and a xylyl group. , Ethyl phenyl, propyl phenyl, butyl phenyl, pentyl phenyl, hexyl phenyl, heptyl phenyl, octyl phenyl, nonyl phenyl, decyl phenyl, benzyl phenyl, dodecyl phenyl, An alkylaryl group having 7 to 26 carbon atoms such as a getylphenyl group, a dibutylphenyl group, and a octylphenyl group (the alkyl group may be linear or branched, and the position of substitution with the aryl group is arbitrary. A)). Examples of arylalkyl groups include, specifically, C7-C12 alkyl groups such as benzyl, phenylethyl, phenylpropyl, phenylbutyl, phenylpentyl, and phenylhexyl. Reel alkyl groups (these alkyl groups may be linear or branched). The hydrocarbon group represented by R ¹ is a linear or branched alkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a linear or branched alkyl aryl group. The alkyl group is preferably an alkyl group having 3 to 5 carbon atoms, particularly in terms of excellent base number maintenance, and particularly a linear or branched carbon number in terms of excellent high-temperature detergency. It is preferably an alkyl group having 6 to 18 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a linear or branched alkyl aryl group. In the present invention, in the case of a linear or branched alkyl group having 6 to 18 carbon atoms, preferably 6 to 12 carbon atoms, in terms of low volatility and the most excellent high-temperature detergency and friction reducing effect. Is desirable. It is preferred that all R ¹ are the same.

By using the phosphate triester represented by the general formula (1), the metal content of the composition can be further reduced as compared with the case where a metal-based wear inhibitor such as ZDTP is used. It is possible to obtain a lubricating oil composition having higher anti-wear property, base number maintenance property and high-temperature detergency as compared with the case of using phosphoric acid monoester, diester or phosphite.

The lower limit of the content of the component (A) in the present invention is 0.01% by mass, preferably 0.02% by mass, and preferably 0.05% by mass in terms of phosphorus element based on the total amount of the composition. It is particularly preferred that the content is mass%. On the other hand, the upper limit thereof is 0.2% by mass, preferably 0.15% by mass, and particularly preferably 0.1% by mass in terms of the phosphorus element based on the total amount of the composition. If the content of the component (A) is less than 0.01% by mass, the sufficient effect of the present invention cannot be obtained. On the other hand, if the content of the component (A) exceeds 0.2% by mass, the exhaust gas purifying catalyst It is not desirable because of concerns about the impact on the environment. The component (B) in the lubricating oil composition for an internal combustion engine of the present invention is succinic acid imid and / or a derivative thereof.

Examples of the succinic acid imid include a monosuccinic acid imid represented by the following general formula (2) and a piscosuccinic imid represented by the following general formula (3). (3)

In the general formula (2) or (3), R ^{1 Q} , R ¹¹ and R ¹² each independently represent a polybutenyl group, and n represents an integer of 2 to 7. In the present invention, a bis-type succinic acid imid represented by the general formula (3) is preferable in that the effects of the present invention can be further enhanced.

The polybutenyl group represented by R ^{1 G} , R ¹¹ and R ¹² preferably has a number average molecular weight of 700 or more, more preferably 900 or more, and a polybutenyl group. Has a number average molecular weight of preferably 350 or less, more preferably 250 or less, particularly preferably 150 or less. By setting the number average molecular weight to 700 or more, it becomes possible to obtain a lubricating oil composition having excellent detergency and dispersibility. On the other hand, by setting the number average molecular weight to 350 or less, it becomes possible to obtain a lubricating oil composition excellent in low-temperature fluidity. The lower limit value of n is 2, preferably 3, while the upper limit value of n is 7, and preferably 6, because of its superior sludge control effect. Here, the polybutenyl group can be obtained from a mixture of 1-butene and isobutene or polybutene (polyisobutene) obtained by polymerizing high-purity isobutene with a catalyst such as aluminum chloride or boron fluoride. Those having a vinylidene structure at the terminal are usually contained in an amount of 5 to 100 mol%. Further, as the polybutene (polyisobutene), those in which trace amounts of fluorine and chlorine remaining due to the catalyst in the production process have been further removed by an appropriate treatment method can be used. The content of halogen elements such as fluorine and chlorine is preferably 50 mass ppm or less, more preferably 10 mass ppm. Below, more preferably 5 mass ppm or less, particularly preferably 1 mass ppm or less can be used.

The method for producing the succinic acid imide represented by the general formula (2) or (3) is not particularly limited. For example, chlorinated polybutene, preferably polybutene from which chlorine and fluorine have been sufficiently removed, is reacted with maleic anhydride at 100 to 200 ° C. to obtain polybutenyl succinic acid, diethylene triamine, A method of reacting with a polyamine such as triethylenetetramine, tetraethylenepentamine, or penethyleneethylenehexamine can be used. In the case of producing a succinic acid imide, the polybutenyl succinic acid may be reacted twice as much as the polyamine (molar ratio), and in the case of producing a monosuccinic acid imide, the polybutenyl succinic acid may be reacted. Succinic acid and polyamine may be reacted in equal amounts (molar ratio).

Derivatives of succinic imid include, for example, amino groups and / or imino groups remaining by reacting an oxygen-containing organic compound or a boron compound with a compound represented by the general formula (2) or (3). It may be a compound in which a part or all of the compound is neutralized or amidated.

Specific examples of the oxygen-containing organic compound include, for example, formic acid, acetic acid, glycolic acid, propionic acid, lactic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, argargonic acid, pulpric acid, Monocarboxylic acids having 1 to 30 carbon atoms, such as pendecylic acid, lauric acid, tridecanoic acid, myristic acid, pennodecanoic acid, norremitic acid, margaric acid, stearic acid, oleic acid, nonadecanoic acid, and eicosanoic acid; Polycarbonic acids having 2 to 30 carbon atoms such as acids, fluoric acid, trimellitic acid, and pyromellitic acid, or anhydrides or ester compounds thereof; alkylene oxides having 2 to 6 carbon atoms; hydroxy (poly ) Oxyalkylene carbonate and the like. By causing such an oxygen-containing organic compound to act, for example, a part or all of the amino group or imino group in the compound of the general formula (2) or (3) is changed to a structure represented by the following general formula (4). It is estimated that

N-COR (4)

/ Here, R ¹³ represents a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, an alkenyl group, an alkoxy group, or a hydroxy (poly) oxyalkylene group represented by — (R ¹⁴ ) _m H. And R "represents an alkylene group having 1 to 4 carbon atoms, and m represents an integer of 1 to 5.

Examples of the boron compound include boric acid, borates, and borate esters. Specific examples of boric acid include orthoboric acid, metaboric acid and tetraboric acid. Examples of the borate include alkali metal salts, alkaline earth metal salts, and ammonium salts of boric acid. More specifically, for example, lithium metaborate, lithium tetraborate, lithium pentaborate, Lithium borate such as lithium perborate; sodium borate such as sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate; metaboric acid Potassium borate such as potassium, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate; calcium metaborate, calcium diborate, tricalcium tetraborate, pentacalcium tetraborate, Calcium borate such as calcium hexaborate; magnesium metaborate, magnesium diborate, tri-tetraborate Neshiumu, tetraborate five magnesium, six e © magnesium such as magnesium borate; and metaborate Anmoniumu, tetraborate Anmoniumu, Goho © acid Anmoniumu, Ru include boric acid Anmoniumu such as eight borate Anmoniumu. Examples of the borate ester include an ester of boric acid and preferably an aliphatic alcohol having 1 to 6 carbon atoms, and more specifically, for example, monomethyl borate, dimethyl borate, trimethyl borate, Examples include monoethyl borate, getyl borate, triethyl borate, monopropyl borate, dipropyl borate, propyl borate, monobutyl borate, dibutyl borate, and tributyl borate. There is no particular limitation on the mass ratio (B / N ratio) of the amount of boron to the amount of nitrogen in the succinic acid imidized with the boron compound, but from the viewpoint of improving the base number maintenance property and high-temperature detergency, 0.1. To 1.2, more preferably 0.2 to 1.0, and particularly preferably 0.3 to 0.9.

In the present invention, as the component (B), one or more kinds selected from the above-mentioned succinic acid imids and derivatives thereof can be used.

J 0. In the present invention, the lower limit of the content of the component (B) is 0.01% by mass, preferably 0.05% by mass, in terms of nitrogen element, based on the total amount of the composition. It is particularly preferred that the content is 0.8% by mass. On the other hand, the upper limit is 0.3% by mass, preferably 0.2% by mass, particularly preferably 0.15% by mass, based on the total amount of the composition, in terms of the nitrogen element exchange amount. preferable. When the content of the component (B) is less than 0.01% by mass, the effects of the present invention cannot be obtained. When the content exceeds 0.3% by mass, the low-temperature viscosity characteristics and It is not preferable because the demulsifying property is deteriorated. The component (C) in the present invention is an alkali metal or alkaline earth metal detergent. The component (C) includes alkali metal or alkaline earth metal sulfonate, alkali metal or alkaline earth metal phenate, and alkali metal or alkaline earth metal salicylate. In the present invention, it is preferable to use one or more kinds of alkaline metal or alkaline earth metal-based detergents selected from the group consisting of these, particularly preferably alkaline earth metal-based detergents. it can.

Examples of the alkaline earth metal sulfonate include alkali metal alkylaromatic sulfonic acids obtained by sulfonating an alkylaromatic compound having a molecular weight of 300 to 150, preferably 400 to 700. It is an earth metal salt, particularly a magnesium salt and / or a calcium salt, and a calcium salt is preferably used.

Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid.

As the petroleum sulfonic acid, a so-called mahoganic monoacid, which is generally obtained by sulfonating an alkyl aromatic compound of a lubricating oil fraction of a mineral oil, which is by-produced during the production of white oil, is used. Examples of the synthetic sulfonic acid include by-products from an alkylbenzene production plant, which is a raw material for detergents, and alkylation of oligomers of olefins (ethylene, propylene, etc.) having 2 to 12 carbon atoms to benzene. The obtained sulfonated alkylbenzene having a linear or branched alkyl group or the sulfonated alkylnaphthalene such as dinonylnaphthalene is used. Also, when sulfonating these alkyl aromatic compounds, The sulfonating agent is not particularly limited, but fuming sulfuric acid or sulfuric anhydride is usually used. Alkaline earth metal phenates include, for example, alkyl phenols, alkyl phenol sulphides, alkaline earth metal salts of Mannich reactants of alkyl phenols, especially magnesium salts and calcium salts. Specifically, those represented by the following general formulas (5), (6) and (7) can be mentioned.

In the above general formulas (5), (6) and (7), R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ and R ^{2 H} may be the same or different, and each may have a different number of carbon atoms. Represents 4 to 30, preferably 6 to 18 linear or branched alkyl groups; MM ² and M ³ each represent an alkaline earth metal, preferably calcium or magnesium; X is 1 or Shows 2.

As the alkyl group represented by R ²¹ R ²² , R ²³ , R ²⁴ , R ²⁵ and R ² ", specifically, a butyl group, a pentyl group, a hexyl group, a heptyl group, Group, octyl group, nonyl group, decyl group, pendecyl group, dodecyl group, tridecyl group, tetradecyl group, pendecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henycosyl Group, docosyl group, tri Examples include a cosyl group, a tetracosyl group, a pencosyl group, a hexacosyl group, a heptoxycosyl group, an octacosyl group, a nonacosyl group, and a triacontyl group. These may be linear or branched. These may also be primary, secondary or tertiary alkyl groups.

Examples of the alkaline earth metal salicylate include alkali earth metal salts of arylalkyl salicylic acid, particularly, magnesium salt and calcium salt. Specific examples include compounds represented by the following general formula (8).

In the general formula (8), R ^{2 7} is 4 carbon 3 0, preferably represents a straight-chain or branched alkyl group. 6 to 1 8, M ⁴ represents an alkaline earth metal, preferably calcium or magnesium Show.

The alkyl group represented by R ^{2 7,} specifically, butyl, pentyl, hexyl, heptyl, Okuchiru group, nonyl group, decyl group, Undeshiru group, dodecyl group, tridecyl group, tetradecyl Group, pentadecyl group, hexadecyl group, hepdecyl decyl group, octadecyl group, nonadecyl group, icosyl group, henycosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptayl Examples thereof include a sucosyl group, an octacosyl group, a nonacosyl group, and a triacontyl group, which may be linear or branched. These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

The alkaline earth metal sulfonate, alkaline earth metal phenate and alkaline earth metal salicylate include the above-mentioned alkyl aromatic sulfonic acid, alkylphenol, alkylphenol sulfide, alkylphenol Mannich reaction product, Alkyl salicylic acid or the like is directly reacted with alkaline earth metal bases such as magnesium and / or calcium alkaline earth metal oxides and hydroxides, or is once reacted with sodium salts such as sodium salts and potassium salts. Neutral (normal salt) obtained by substituting an alkaline earth metal salt with an alkaline earth metal salt, etc. Neutral (normal salt) alkaline earth metal phenate and neutral (normal salt) alkaline earth metal salicylate; or neutral alkaline earth metal sulfonate, neutral alkaline earth metal phenate and neutral alkaline earth Basic alkaline earth metal sulfonates, basic alkaline earth metal phenates and bases obtained by heating metal salicylates and excess alkaline earth metal salts and alkaline earth metal bases in the presence of water Alkaline earth metal salicylates; furthermore, alkaline earth metal hydroxides in the presence of neutral alkaline earth metal sulfonates, neutral alkaline earth metal phenates and neutral alkaline earth metal salicylates (Ultrabasic) alkaline earth metal sulfonate, overbasic (ultrabasic) obtained by reacting carbon dioxide or boric acid with ) Includes alkaline earth metal phenates and overbased (ultrabasic) alkaline earth metal salicylates.

In the present invention, the above-mentioned neutral alkaline earth metal salts, basic alkaline earth metal salts, overbased (ultrabasic) alkaline earth metal salts, and mixtures thereof can be used. Although the base number is optional, the total base number is usually 50 OmgKOH / g or less, preferably 60 to 400111 1 <〇11 /. Here, the total base number means the total base number by the perchloric acid method measured in accordance with 7. of JISK 2501 (1992) “Petroleum products and lubricating oils—Testing method for neutralization number”. I do.

Alkaline earth metal-based detergents are usually diluted and diluted with a light lubricating base oil or the like, and are available, but generally have a metal content of 1.0 to 20 mass%. %, Preferably from 2.0 to 16% by mass.

The metal ratio of the component (C) used in the present invention is not particularly limited, but usually 1 to 2 °, preferably 1 to 15 is used.

In the present invention, it is preferable that an alkali metal or alkaline earth metal salicylate-based detergent is essentially contained as the component (C). The metal ratio is preferably 3 or less, more preferably 2.6 or less, further preferably 2 or less, and particularly preferably 1.5 or less. In addition, such an alkali metal or alkaline earth metal salicylate-based detergent may be used alone or as a mixture having a different metal ratio. For example, an alkali metal or alkaline earth metal salicylate having a metal ratio of 2 or less, preferably 1.5 or less, particularly 1.2 or less As an essential component, or a combination of a metal ratio of 1.5 or less, preferably 1.2 or less, and a metal ratio of more than 1.5, especially 2.6 The metal ratio in the mixture of alkali metal and alkaline earth metal salicylate is adjusted to 1.3 or more, preferably 2.3 or less, more preferably 2 or less, particularly preferably 1.5 or less. May be. By adjusting the metal ratio of Al-ri-metal or Al-ri-earth metal salicylate to the range of 1.3 to 2.3, the base number retention to the content of component (C), high-temperature detergency, and Can further improve the effect of improving low friction.

The component (C) comprises an alkali metal or alkaline earth metal salicylate-based detergent having a metal ratio of 1.5 or less, preferably 1.2 or less, and an alkali metal or alkali earth. It is preferable to use a metal sulfonate-based detergent in combination. The metal ratio of the alkali metal or alkaline earth metal sulfonate-based detergent is not particularly limited, but is usually 1 to 20, preferably 1 to 15, and particularly preferably 5 to 12. With the component (C) having such a constitution, the effect of improving the base number maintenance property, high-temperature detergency, and low friction property can be further enhanced.

The metal ratio here is represented by the valence of the metal element X the content of the metal element (mol) / the content of the soap group (that is, the group such as an alkyl salicylic acid group) (mol). Indicates the content of the metal or the alkaline earth metal relative to the content of the alkylsalicylic acid group and the alkyl sulfonic acid group in the alkaline metal or alkaline earth metal detergent.

The lower limit of the content of the alkali metal or alkaline earth metal detergent (C) in the present invention is 0.05 mass in terms of the amount of alkali metal or alkaline earth metal element based on the total amount of the composition. %, Preferably 0.1% by mass, more preferably 0.15% by mass, particularly preferably 0.2% by mass. On the other hand, the upper limit is 1% by mass, preferably 0.5% by mass, more preferably 0.4% by mass, in terms of alkali metal or alkaline earth metal element, based on the total amount of the composition. . When the content of the component (C) is less than 0.05% by mass, the excellent base number maintenance property and high-temperature detergency as in the present invention cannot be exhibited, while the content of the component (C) is 1% by mass. If it exceeds, it is not preferable because the effect corresponding to the content cannot be obtained. The component (D) in the lubricating oil composition for an internal combustion engine of the present invention is a phenolic antioxidant and / or an amine antioxidant.

Examples of phenolic antioxidants include 4,4, -methylenebis (2,6-di-tert-butylphenol), 4,4,1-bis (2,6-di-tert-butylphenyl), 4,4 '—Bis (2-methyl-1-6-tert-butylphenol), 2,2'-Methylenebis (4-ethyl-16-tert-butylphenol), 2,2, -methylenebis (4_methyl-16-tert-butylphenol) 2,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4,1-isopropylidenebis (2,6-di-tert-butylphenol), 2,2'-methylenebis 4 one methyl one 6-nonylphenol), 2, 2 '- iso butylidene bis (4, 6-dimethyl phenol), 2, 2 ⁵ - methylene Nbisu (4 one methyl one 6-cyclohexyl phenol), 2, 6—Di-tert-butyl L-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-1-6-tert-butylphenol, 2,6-di-tert-dimethyldimethylamino-p-cresol, 2, 6-di-tert-butyl-4 (N, N'-dimethylaminomethylphenol), 4, 4'-thiobis

(2-methyl-6-tert-butylphenol), 4,4,1-thiobis (3-methyl-1-6-tert-butylphenol), 2,2'-thiobis (4-methyl-6-tert-butylphenol) , Bis (3-methyl-1-hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-14-hydroxybenzyl) sulfide, 2, 2'- Thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyhydroxyphenyl) probionate], tridecyl-3_ (3,5-di-tert-butyl-14-hydroxyphenyl) propionate, pen Eri erythritylute thrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octyldecyl-3

(3,5-di-tert-butyl-14-hydroxyphenyl) propionate, octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) pionate, octyl-3- (3-methyl-1 5-tert-butyl-1-hydrogen Roxyphenyl) propionate is a preferred specific example. These may be used as a mixture of two or more.

Examples of the amine-based antioxidant include phenyl-α-naphthylamine, alkynolepheninole-α-naphthinoleamine, and dialkyldiphenylamine. These may be used as a mixture of two or more. Here, the alkyl group generally represents an alkyl group having 1 to 16 carbon atoms.

The phenolic antioxidant and the amine antioxidant may be used alone, but are preferably used in combination because the effects of the present invention can be further enhanced.

In the lubricating oil composition of the present invention, the lower limit of the content of the component (D) is preferably 0.01% by mass based on the total amount of the composition in order to further enhance the base number retention and high-temperature detergency. Is 0.1% by mass, more preferably 0.5% by mass, particularly preferably 1.0% by mass. On the other hand, the upper limit of the content of the component (D) is 3.0% by mass, preferably 2.5% by mass, and more than 3.0% by mass, based on the total amount of the composition. It is not preferable because sufficient antioxidant property cannot be obtained corresponding to the amount. The lubricating oil composition for an internal combustion engine of the present invention may contain an antiwear agent other than the component (II).

As the antiwear agent other than the component (II), a metal salt of a thiophosphate or a phosphate represented by the following general formula (9), a thiophosphate or a thiophosphate represented by the following general formula (10): Phosphites or thiophosphites, or their metal salts or amines, as well as acid esters, or metal salts or amine salts thereof, and metal salts or amine salts thereof, thiophosphoric acid triesters zinc dialkyldithiophosphates, dialkyldithiocarbamines Examples of the anti-wear agent include phosphorus and phosphorus or sulfur-containing abrasion inhibitors such as zinc oxide, molybdenum dialkyldithiophosphate, molybdenum dialkyldithiophosphate, disulfide, sulfide sulfide, and sulfurized oils.

R ^3Q , R ³¹ , R ³² , R ³³ , R ³⁴ and R ^{35 each} independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. The component (A) has the same meaning as R ¹ in the general formula (1), and the preferred range is also the same.

X ¹ , X ² , X ³ , XX ⁵ and X ^{6 each} independently represent an oxygen atom or a sulfur atom, and at least one of them is an oxygen atom and two or more are oxygen atoms. It is particularly preferred that all are oxygen atoms. By containing at least one oxygen atom, the sulfur content in the composition can be further reduced, and the amount of sulfuric acid generated when subjected to oxidation or thermal decomposition can be reduced, and thus the base number is significantly consumed. Can be suppressed.

Specific examples of the metal atom represented by Y include zinc, copper, iron, lead, nickel, silver, and manganese. Y is preferably zinc from the viewpoint that higher wear prevention performance can be obtained.

U represents hydrogen (proton), a monovalent metal ion or an ammonium ion, k is an integer of 1 to 20, and represents the number of U ions. k is preferably an integer of 1 to 10. More preferably, it is an integer of 1 to 8.

The fine metal ion represented by U is a metal atom capable of forming a salt, and examples thereof include alkali metals such as lithium, sodium, potassium, and cesium. Examples of the ammonium ion include compounds derived from this ion, for example, a nitrogen-containing compound capable of forming an amine salt.

Examples of the nitrogen-containing compound include ammonia, monoamine, diamine, and polyamine. More specifically, methylamine, ethylamine, propylamine, butyramine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, pendecylamine, dodecylamine, tridecylamine, tetradecylamine, penhexadecylamine Lamine, hepamine decylamine, octadecylamine, dimethylamine, methylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, didindecylamine, didodecylamine, didodecylamine Min, ditetradecylamine, dipentyldecylamine, dihexadecylamine, dihepdecylamine, dioctyldecylamine, methylethylamine, methylpropylamine, methylbutylamine, ethylpropylamine, ethylbutylamine, probutylbutylamine An alkylamine having an alkyl group having 1 to 30 carbon atoms (the alkyl group may be linear or branched);

Alkenylamines having an alkenyl group having 2 to 30 carbon atoms (these alkenyl groups may be straight-chain or branched) such as ethenylamine, propenylamine, butenylamine, octenylamine, and oleylamine; methanolamine, ethanolanolamine , Propanolamine, bushanolamine, pentanolamine, hexanolamine, heptanoamine, octanolamine, nonanoamine, methanolethanolamine, methanolpropanolamine, methanolbutanolamine, ethanolpropanol Alcohol groups having 1 to 30 carbon atoms, such as ethanol, ethanolamine, propanolamine, etc. (these alcohol groups may be linear or branched) Alkanolamines; Alkylenediamines having an alkylene group having 1 to 30 carbon atoms, such as tylenediamine, ethylenediamine, propylenediamine, and petylenediamine; polyamines such as dimethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine; C8 to C20 alkyls such as the above monoamines, diamines and polyamines, such as perdecyl getylamine, perdecyl dimethylamine, dodecyl dipropanolamine, oleyl phenol, oleyl propylene diamine and stearyl tetraethylene pentamine A heterocyclic compound such as a compound having a group or an alkenyl group, N-hydroxylethylolimidazoline or the like; an alkylene oxide adduct of these compounds; and a mixture thereof.

In the lubricating oil composition for an internal combustion engine of the present study, the lubricating oil composition other than the component (A) is used. When a sulfur-containing antiwear agent is contained in the antiwear agent, its content is not particularly limited. However, the content should be 0.1% by mass or less in terms of sulfur element based on the total amount of the composition. It is more preferable that the content be 0.09% by mass or less. It is particularly preferable not to contain a sulfur-containing antiwear agent. When the content of the sulfur-containing antiwear agent is 0.1% by mass or less, it is possible to obtain a composition having extremely excellent base number retention and high-temperature detergency.

When a phosphorus-containing antiwear agent containing no sulfur is contained in the antiwear agent other than the component (A), the content is usually 0 in terms of the phosphorus element based on the total amount of the composition. 0.1 to 0.2% by mass. Even in such a case, the adverse effect on the exhaust gas purifying catalyst and the like is feared. Therefore, it is preferable that the amount of the phosphorus element in the composition together with the component (A) does not exceed 0.2% by mass, and 0.15% % Is particularly preferred. The lubricating oil composition for an internal combustion engine of the present invention is excellent in antiwear properties, base number maintenance properties and high-temperature detergency, but in order to further improve its performance, an optional additive is added depending on the purpose. Can be added. Examples of such additives include a viscosity index improver, an ashless dispersant other than the component (B), a metal-based detergent other than the component (C), a friction modifier, a corrosion inhibitor, an anti-honey agent, and a demulsifier. , A metal deactivator, an antifoaming agent, and a coloring agent.

As the viscosity index improver, specifically, a so-called non-dispersion type viscosity index improver such as a copolymer of one or more kinds of monomers selected from various methacrylates or a hydrogenated product thereof, Or a so-called dispersion type viscosity index improver obtained by copolymerizing various methacrylates containing a nitrogen compound; non-dispersion type or dispersion type ethylene monoolefin copolymerization copolymer (propylene is 1-butene; 1-butene; -Pentene, etc.) or hydrides thereof, polybutylene or hydrogenated products thereof, styrene-gen hydrogenated copolymers, styrene-maleic anhydride ester copolymers, and polyalkylstyrenes.

The molecular weight of these viscosity index improvers is preferably selected in consideration of shear stability. Specifically, the number average molecular weight of the viscosity index improver is, In the case of dispersed polymethacrylates, those of 5,000 to 1,000,000, preferably 10,000 to 350,000, are of polyisobutylene or its hydrides, 800 to 5,000, preferably 1 to 500,000. 2,000 to 4,000 are ethylene-monoolefin copolymers or hydrides thereof, preferably 800 to 500,000, more preferably 3,000 to 200,000.

In addition, when an ethylene-one-year-old olefin copolymer or a hydride thereof is used among these viscosity index improvers, a lubricating oil composition having particularly excellent shear stability can be obtained. One or more compounds arbitrarily selected from the above viscosity index improvers can be contained in an arbitrary amount. The content of the viscosity index improver is usually 0.1 to 20.0% by mass based on the total amount of the lubricating oil composition.

Examples of the ashless dispersant other than the component (B) include benzylamine, polyamine and derivatives thereof having at least one alkyl or alkenyl group having 40 to 400 carbon atoms in the molecule.

Examples of the friction modifier include aliphatic amines, fatty acids, fatty acid esters, and aliphatic alcohols having an alkyl or alkenyl group having 6 to 30 carbon atoms. Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiazole, thiadiazole, and imidazole compounds.

Examples of the promoting agent include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinate, and polyhydric alcohol ester.

Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.

Examples of the metal deactivator include, for example, imidazoline, pyrimidine derivative, alkylthiazole, mercaptobenzothiazole, benzotriazole or a derivative thereof, 1,3,4-thiadiazole polysulfide, 1,3,4 —Thiadiazolyl-1,2,5-bisdialkyldithiocarbamate, 2— (Alkyldithi) And benzimidazole, and?-(0-carboxybenzylthio) propionnitrile.

Examples of the antifoaming agent include silicone, fluorosilicone, and fluoroalkyl ether.

When these additives are contained in the lubricating oil composition of the present invention, the content thereof is based on the total amount of the lubricating oil composition, and the ashless dispersant other than the component (B) and the metal-based detergent other than the component (C) are used. Agent, antioxidant other than component (D), friction modifier, corrosion inhibitor, antioxidant, anti-emulsifier 0.01 to 5% by mass, and metal deactivator 0.00%. The amount is usually selected from the range of 5 to 1% by mass, and the range of 0.005 to 1% by mass for the antifoaming agent.

In the lubricating oil composition for an internal combustion engine of the present invention, it is preferable to limit the content of the sulfur-containing additive together with the above-mentioned sulfur-containing antiwear agent. ) Is preferably 0.1% by mass or less, more preferably 0.09% by mass or less, in terms of sulfur element, based on the total amount of the composition, and more preferably 0.09% by mass or less. (Including a sulfur-containing wear inhibitor) is particularly preferred. Note that commercially available additives generally contain solvents used when synthesizing the additives and diluent oils (for example, solvent refined mineral oils) for improving the handling of the additives. The sulfur-containing additive referred to in the above does not mean a sulfur compound caused by these solvents or diluent oil.

In the present invention, even if the sulfur content due to these solvents and diluent oils is contained, the total sulfur content in the composition is not more than 0.2% by mass, preferably not more than 0.15% by mass. It is particularly preferably at most 0.1% by mass. As a result, a composition which is excellent in anti-wear properties, basic lung maintenance properties and high-temperature cleanability, and which maintains the performance of an exhaust gas purification catalyst and the like can be obtained. In the present invention, these solvents and diluent oils may be used as highly hydrocracked base oils having a sulfur content of 10 mass ppm or less, or GTLW ax (gas-to-liquid) containing substantially no sulfur. · The use of base oils or synthetic oils, etc., produced by isomerization of wax) and the absence of sulfur-containing additives ensure that the total sulfur content of the composition is less than 10 mass ppm. It is also possible to obtain a certain composition or a composition that is practically free. [Industrial applicability]

The lubricating oil composition for an internal combustion engine according to the present invention is capable of preventing oxidation without reducing the anti-wear property even if a sulfur-containing anti-wear agent and an anti-oxidant such as ZDTP are reduced or not used at all. It has extremely improved properties, has excellent base number maintenance properties, that is, has excellent long drain performance, and also has excellent high-temperature cleanliness and low friction properties.

Further, the lubricating oil composition for an internal combustion engine according to the present invention can reduce the total sulfur content of the composition to 0.2% by mass or less, so that the exhaust gas purifying catalyst and the like are poisoned by sulfur. Can be reduced extremely, and can be suitably used for an engine equipped with an exhaust gas aftertreatment device such as an exhaust gas purification catalyst.

Further, the lubricating oil composition for an internal combustion engine of the present invention is a lubricating oil that requires anti-wear properties, base number maintenance properties and high-temperature detergency, such as a lubricating oil for a drive train of an automatic or manual transmission, a wet type It can be suitably used as a lubricating oil such as brake, hydraulic oil, turbine oil, gear oil, bearing oil and the like.

[Best Mode for Carrying Out the Invention]

Hereinafter, 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.

(Examples 1 to 4 and Comparative Examples 1 and 2)

Lubricating oil compositions for internal combustion engines having the compositions and properties shown in Table 1 (Examples 1 to 4 and Comparative Examples 1 and 2) were prepared. The composition in which the sulfur content in the composition is 0.05% by mass is due to the diluent oil of the additive. The performances of the lubricating oil compositions for internal combustion engines obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were evaluated by the following performance evaluation tests. (1) Temporal change of total base number by I SOT

With the ISOT test (165.5 ° C) based on JISK 2514, the change over time of the total base number (hydrochloric acid method) when the test oil was forcibly deteriorated was measured. Table 1 shows the evaluation results. The higher the total base number residual ratio, the higher the base number maintenance performance, indicating that this is a long drain oil that can be used for a longer time.

As shown in Table 1, the compositions of the present invention (Examples 1 to 4) contained ZDTP (sulfur-containing antiwear agent) in a general amount as a lubricating oil for internal combustion engines (0.16% by elemental sulfur). It can be seen that the base number retention is extremely high as compared with the compositions (Comparative Examples 1 and 2) containing 0.1% by mass and 0.08% by mass of the elemental phosphorus. Among them, the triphenyl phosphate-containing composition (Example 4), and particularly the triptyl phosphate-containing composition (Example 3), have a higher base value than the trioctyl phosphate-containing composition (Example 1). Is extremely high.

(2) Temporal change of total base number by NOx absorption test

Japanese Tribology Conference Proceedings 1992, 10, and 465 (150 ° C, NOx: 1 185 ppm). The hydrochloric acid method) was measured over time. Table 1 shows the evaluation results. The smaller the decrease in total base number, the higher the base number maintenance performance even in the presence of NOx, which is used in internal combustion engines, indicating that this is a long drain oil that can be used for a longer time.

As shown in Table 1, the compositions of the present invention (Examples 1 to 4) have excellent base number retention properties and are exposed to NOx such as lubricating oil for internal combustion engines, similar to the results of the above-mentioned I SOT. It can be seen that the sample also exhibits excellent long drain characteristics.

(3) Anti-wear properties as seen in the Falex test

Falex test in accordance with ASTM D 3233 (Method A, 290 rpm, room temperature, measured the seal when the test piece seized. The evaluation results are shown in Table 1. Large seizure load It shows that the wear resistance is more excellent.

As shown in Table 1, the composition of the present invention is equal to or more than the compositions of Comparative Examples 1 and 2. It can be seen that the steel exhibits excellent wear prevention performance.

(4) High temperature cleaning performance in hot tube test

A hot tube test was performed in accordance with JP I-5 S-5599. The score was 10 points for colorless and transparent (no stain) and 0 point for black and opaque, and the evaluation was made with reference to a standard tube that was previously created in one step. If the rating is 6 or more at 290 ° C, the lubricating grease for ordinary gasoline engines and diesel engines is excellent in cleanliness. It is preferable to exhibit excellent cleanliness even at a temperature of at least ° C. As shown in Table 1, it can be seen that the composition of the present invention exhibits extremely excellent high-temperature cleanliness even under test conditions of 300 ° C or higher. In particular, when trioctyl phosphate is used, it is considered to be lower in volatility than tributyl phosphate, and exhibits extremely excellent high-temperature detergency.

(Examples 5 to 9 and Comparative Example 3)

Lubricating oil compositions for each internal combustion engine having the compositions and properties shown in Table 2 (Examples 5 to 9 and Comparative Example 3) were prepared and subjected to the following performance evaluations. The results are shown in Table 2. The composition of Example 9 is the same as the composition of Example 1 in Table 1, and the composition of Comparative Example 3 is the same as the composition of Comparative Example 1 in Table 1.

(5) Low friction performance in LFW-1 boundary friction test

Using the LFW-1 tester, LFW-1 boundary friction tests were performed at a load of 1001 bs, a temperature of 100 ° C, and various sliding speeds.

As is clear from the results in Table 2, the composition of Example 9 (the composition of Example 1 in Table 1) had lower friction than the composition of Comparative Example 3 (the composition of Comparative Example 1 in Table 1). It can be seen that the characteristics are also excellent. In addition, it can be seen that extremely low friction performance is exhibited particularly when an alkaline earth metal salicylate having a low metal ratio is used as an essential component (Examples 5 to 8). These compositions have salt a value maintenance properties, The anti-wear property and high-temperature detergency show the same or better performance as the composition of Example 9. The component (C) in Example 6 was a mixture of calcium salicylates having a metal ratio of 1.0 and 2.7, and the metal ratio was 1.46. It can be seen that the content of the component (C) in the above can be reduced, and that the friction coefficient decreases synergistically, especially in the high sliding speed range. When triptyl phosphate and triphenyl phosphate were used instead of trioctyl phosphate as the component (A), low friction performance was superior to that of Comparative Example 3, but trioctyl phosphate was the most excellent The friction performance was shown.

table 1

Table 2

2) Bis type, number average molecular weight of polybutenyl group: 1300, nitrogen content: 1.8% by mass

3) Calcium salicylate, total base number: 70 mgKOH / g, calcium content: 2,3% by mass, metal ratio: 1.0

4) Calcium salicylate, total base number: 120 mgKOH / g, calcium content: 4.15 mass%, metal ratio: 1.8

5) Calcium salicylate, total base number: 170 _mg KOH / g, calcium content: 6.2% by mass, metal ratio: 2,7

6) Calcium sulfonate, total base number: 300 mgKOH / g, calcium content: 12% by mass, sulfur content: 3.3% by mass, metal ratio: 10.0

7) Octyl-1- (3,5-di "t-butyl-1-hydroxyphenyl) propionate, sulfur content: 0.0% by mass

8) Alkyldiph Inylamin (alkyl group: mixture of G4 and C8)

9) Ethylene monoolefin copolymer system

10) zinc di (1.3 dimethylbutyl) dithiophosphate, sulfur content: 18.8% by mass, phosphorus content: 9.4% by mass

Claims

The scope of the claims

1. In a lubricating base oil, (A) a phosphoric acid triester represented by the general formula (1) in an amount of 0.01 to 0.2% by mass in terms of phosphorus element, and (B) succinic acid imidate and / or 0.01 to 0.3% by mass of the derivative in terms of nitrogen element, (C) 0.05 to 1% by mass in terms of metal element of alkali metal or alkaline earth metal detergent, and (D) A lubricating oil composition for an internal combustion engine comprising 0.01 to 3% by mass of a phenolic antioxidant and / or an amine antioxidant.

〇 = P (OR ri 3 (1)

(In the formula, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, which may be the same or different.)

2. The internal combustion engine according to claim 1, wherein the alkali metal or alkaline earth metal detergent contains an alkali metal or alkaline earth metal salicylate detergent. Lubricating oil composition.

3. The above-mentioned metal or alkaline earth metal salicylate-based detergent has a metal ratio represented by valence of metal element X metal element content (mo 1) / soap group content (mo 1). 3. The lubricating oil composition for an internal combustion engine according to claim 2, wherein the lubricating oil composition is an alkaline metal or alkaline earth metal salicylate-based detergent of 3 or less.

4. When the metal or alkaline earth metal-based detergent has a metal ratio of 1.5 or less, expressed by the valence of metal element X metal element content (mol) / soap group content (mol). A mixture of a certain alkali metal or alkaline earth metal salicylate-based detergent and an alkali metal or alkaline earth metal salicylate-based detergent having a metal ratio of more than 1.5. The lubricating oil composition for an internal combustion engine according to Item H.

5. The metal-based detergent has a metal ratio represented by the valence of the metal element X the content of the metal element (mo 1) / the content of the soap group (mo 1) of 1. A mixture of an alkaline metal or alkaline earth metal salicylate-based detergent having an average particle size of 5 or less and an alkaline metal or alkaline earth metal sulfonate-based detergent. 3. The lubricating oil composition for an internal combustion engine according to item 2 above.

6. The lubricating oil composition for an internal combustion engine according to claim 1, further comprising a sulfur-containing abrasion inhibitor having a content of 0.1% by mass or less in terms of a sulfur element.

7. The lubricating oil composition for an internal combustion engine according to claim 1, wherein the total aromatic content of the lubricating base oil is 3% by mass or less and the sulfur content is 50% by mass or less.

8. The lubricating oil composition for an internal combustion engine according to claim 1, wherein the lubricating oil composition is used for an internal combustion engine using a fuel having a sulfur content of 50 mass ppm or less.

9. The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 8, which is used for a gas engine.