KR20120099065A - Lubricating oil composition - Google Patents

Abstract

By blending a specific sulfur-containing compound and a specific polar group-containing compound with the base oil, it is excellent in wear resistance even as low phosphorus, low sulfur and low sulfuric acid ash, and exhibits an excellent friction reduction effect even when used in sliding parts subjected to DLC treatment. It provides a lubricating oil composition.

Description

Lubricant composition {LUBRICATING OIL COMPOSITION}

The present invention relates to a lubricating oil composition. More specifically, the present invention relates to a lubricating oil composition which is excellent in wear resistance even in low phosphorus, low sulfur and low sulfuric acid ash, and exhibits an excellent friction reducing effect even when used in a sliding part subjected to diamond-like carbon (DLC) treatment. will be.

In an engine such as an automobile, an oxidation catalyst, a ternary catalyst, a NO _x storage type reduction catalyst, a diesel particulate filter (DPF), and the like are used to clean exhaust gas. It is known that these exhaust gas purification apparatuses are adversely affected by metal powder, phosphorus powder and sulfur powder in engine oil, and reducing these components is required for deterioration countermeasure of the apparatus.

In addition, in recent years, various technologies have been developed for the purpose of reducing fuel consumption, and for example, surface treatment techniques in sliding parts such as engines are mentioned.

By the way, zinc dithiophosphate (Zn-DTP) has been used for many years as an anti-wearing agent and antioxidant of lubricating oils for internal combustion engines used in gasoline engines, diesel engines, gas engines, and the like. It is considered.

However, since zinc dithiophosphate decomposes, sulfuric acid and phosphoric acid generate | occur | produce, in some cases, the basic compound in engine oil is consumed, the deterioration of lubricating oil is accelerated | stimulated, and an oil renewal period may be shortened extremely. In addition, zinc dithiophosphate may sludge under high temperature conditions, and may deteriorate the cleanliness inside an engine. In addition, since zinc dithiophosphate contains a large amount of phosphorus and sulfur in addition to metal powder (zinc) in a molecule | numerator, it can be considered that it causes a bad influence to an exhaust gas purification apparatus. Therefore, development of a lubricating oil composition excellent in wear resistance is desired even without using zinc dithiophosphate.

Moreover, in the situation where development of the surface treatment technique in a sliding part is advanced as mentioned above, improvement is further calculated | required also regarding a lubricating oil composition. For example, when the conventional lubricating oil was used for the sliding part which performed the DLC process, the friction reduction effect as expected might not be expressed. Therefore, a lubricating oil composition which expresses the outstanding friction reducing effect is desired also when used for the sliding part which carried out DLC process in order to achieve further low fuel consumption.

In order to solve these problems, conventionally, various lubricating oil additives and lubricating oil compositions have been proposed. For example, Patent Literatures 1 to 3 describe additives for lubricating oils and lubricating oil compositions which contain a disulfide compound having a specific structure as a main component. Patent document 4 describes the engine oil which reduces sulfur and phosphorus which are poisoning substances of a reduction catalyst, and is excellent in abrasion prevention performance. Patent Document 5 describes a low friction sliding mechanism having a sliding surface using diamond and interposing a lubricating oil composition containing a specific additive.

Japanese Patent Laid-Open No. 2004-262964 Japanese Patent Laid-Open No. 2004-262965 Japanese Patent Publication No. 2008-056876 Japanese Patent Publication No. 2007-131792 Japanese Patent Publication No. 2008-56735

As described above, development of various lubricant additives and lubricating oil compositions has been conducted so far, but since it is usually required to satisfy a large number of required performances such as performance on catalyst poisoning, abrasion resistance, and a friction reducing effect, lubricating oil is generally required. The lubricating oil composition described in the above was not sufficient. In particular, since zinc dithiophosphate was a very useful additive when improving abrasion resistance and antioxidant resistance, it was difficult to obtain a lubricating oil composition having the same or better performance than the conventional one without using the compound.

The present invention has been made in view of the above circumstances, and as a lubricating oil composition having excellent abrasion resistance even in low servings, low sulfur powders and low sulfuric acid ashes, a lubricating oil composition which further exhibits an excellent friction reducing effect even when used in a sliding part subjected to DLC treatment is used. The purpose is to provide.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching, the present inventors discovered that the said objective can be achieved by using together a specific sulfur containing compound and a specific polar group containing compound. The present invention has been completed based on these findings.

That is,

1. In the base oil, (A) at least 1 sort (s) chosen from the sulfur containing compound represented by following formula (I) and (II), (B) at least 1 sort (s) of polar group chosen from an amino group, an amide group, and a hydroxyl group, and C3-C24 The lubricating oil composition formed by mix | blending the polar group containing compound which has an alkyl group.

(R ¹ to R ¹² are each independently a hydrogen atom; a hydrocarbon group selected from an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group and an aryl group; or an atom selected from an oxygen atom, a nitrogen atom and a sulfur atom in these hydrocarbon groups) And a hetero atom-containing group comprising a compound, and each Y independently represents -O-, -S-, -SO-, -SO ₂ -,-(C = O) O-,-(C = O) NH-, -O (C = O) NH-, -C (= O)-, -N (H)-, -NHCONH-, -N = N-, -NH-C (= NH) -NH-, -SC ( = O)-, -NH-C (= S)-and -NH-C (= S) -NH- represent a divalent group selected, x is an integer of 1 to 3, n is each independently 1 to Is an integer of 5),

2. The polar group-containing compound having at least one polar group selected from the amino group, the amide group and the hydroxyl group and an alkyl group having 3 to 24 carbon atoms is selected from the group consisting of glycerin partial fatty acid esters, glycerin monoether compounds, amine compounds and amide compounds. The lubricating oil composition according to the above 1 which is at least one compound selected from the group consisting of

3. The glycerin fatty acid monoester represented by the following general formula (III) or (V) wherein the polar group-containing compound having at least one polar group selected from the amino group, the amide group and the hydroxyl group and an alkyl group having 3 to 24 carbon atoms is represented by the following general formula (III) or (IV): Or the lubricating oil composition according to the above 1, which is a glycerin monoether compound represented by VI,

(R ¹³ and R ¹⁴ each independently represent an alkyl group having 3 to 24 carbon atoms)

4. The polar group-containing compound having at least one polar group selected from the above (B) amino group, an amide group and a hydroxyl group and an alkyl group having 3 to 24 carbon atoms is an amine compound represented by the following general formula (VII) or an amide compound represented by the following general formula (VIII) The lubricating oil composition according to the above 1,

(R ¹⁵ and R ¹⁷ each independently represent an alkyl group having 3 to 24 carbon atoms, and R ¹⁶ and R ¹⁸ each independently represent a group in which a terminal hydrogen atom of a hydrogen atom or a straight chain alkyl group having 2 to 4 carbon atoms is substituted with a hydroxyl group)

5. The lubricant composition according to any one of the above 1 to 4, wherein the phosphorus content is 0.5% by mass or less and sulfuric acid ash is 0.6% by mass or less based on the total amount of the lubricant composition,

6. The lubricating oil composition according to any one of the above 1 to 5, wherein the phosphorus content is 0% by mass and the sulfuric acid ash is 0.1% by mass or less based on the total amount of the lubricating oil composition, and

7. The lubricating oil composition according to any one of the above 1 to 6, which is a lubricating oil composition for a sliding part subjected to a diamond-like carbon (DLC) treatment.

To provide.

According to the present invention, there is provided a lubricating oil composition which exhibits excellent friction reducing effect even when used in a sliding part subjected to DLC treatment as a lubricating oil composition having excellent wear resistance even in low phosphorus, low sulfur powder and low sulfuric acid ash.

The lubricating oil composition of this invention mix | blends a specific sulfur containing compound and a specific polar group containing compound with base oil, It is characterized by the above-mentioned.

[Base oil]

There is no restriction | limiting in particular as base oil used by this invention, Arbitrary thing can be suitably selected and used from mineral oil or synthetic oil conventionally used as base oil of lubricating oil.

As said mineral oil, the lubricating oil distillate obtained by depressurizing the atmospheric residual oil obtained by atmospheric distillation of crude oil, for example, is subjected to one or more processes of solvent dehydration, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, etc. Refined mineral oil, or wax, mineral oil manufactured by isomerizing GTL wax, etc. are mentioned.

On the other hand, as said synthetic oil, for example, polybutene, polyolefin [alpha-olefin homopolymer or copolymer (for example, ethylene-alpha-olefin copolymer), etc.], various esters (for example, polyol ester, dibasic acid ester) , Phosphate esters, and the like), various ethers (for example, polyphenyl ether, etc.), polyglycol, alkylbenzene, alkylnaphthalene, and the like. Among these synthetic oils, polyolefins and polyol esters are particularly preferable.

In this invention, the said mineral oil may be used individually by 1 type, or may be used in combination of 2 or more type as base oil. Moreover, 1 type may be used for the said synthetic oil, and may be used for it in combination of 2 or more type. Furthermore, one or more mineral oils and one or more synthetic oils may be used in combination.

Although there is no restriction | limiting in particular about the viscosity of base oil, It is preferable that dynamic viscosity in 100 degreeC is the range of 2-30 mm <2> / s, More preferably, it is the range of 3-15 mm <2> / s, More preferably, it is 4-10. It is in the range of mm 2 / s.

If kinematic viscosity in 100 degreeC is 2 mm <2> / s or more, evaporation loss will be small, and if it is 30 mm <2> / s or less, power loss by a viscous resistance is suppressed and a fuel efficiency improvement effect can be obtained.

In addition, the base oil as a% C _A by a ring analysis is used when the content of sulfur to preferably 50 mass ppm or less 3.0 or less. Here,% C _A by ring analysis shows the ratio (percentage) of the aromatic content computed by the ring analysis ndM method. In addition, sulfur content is the value measured based on JISK2541.

% C _A is the base oil of not more than 50 mass ppm sulfur minutes at 3.0 or less, has good oxidation stability, it is possible to provide a lubricant composition capable of suppressing the formation of sludge and increase in acid value. More preferably,% C _A is 1.0 or less, still more preferably 0.5 or less, and still more preferably 30 ppm by mass or less.

In addition, the viscosity index of the base oil is preferably 70 or more, more preferably 100 or more, and still more preferably 120 or more. Base oils with a viscosity index of 70 or more have little change in viscosity due to temperature change.

(Sulfur-containing compound)

In the lubricating oil composition of this invention, the sulfur containing compound represented by following formula (I) or (II) is mix | blended.

In formulas (I) and (II), R ¹ to R ¹² each independently represent a hydrogen atom; A hydrocarbon group selected from an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group and an aryl group; Or a hetero atom-containing group including an atom selected from an oxygen atom, a nitrogen atom and a sulfur atom in these hydrocarbon groups.

The alkyl group represented by R ¹ to R ¹² is preferably an alkyl group having 1 to 30 carbon atoms, and more preferably an alkyl group having 1 to 24 carbon atoms. Specific examples of the alkyl group include, for example, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various hexyl groups, various octyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, and various hexa Decyl group, various octadecyl groups, various icosyl groups, and the like. Moreover, the alkyl group may be substituted by the aromatic group, for example, a benzyl group, a phenethyl group, etc. are mentioned.

The cycloalkyl group represented by R ¹ to R ¹² is preferably a cycloalkyl group having 3 to 30 carbon atoms, and more preferably a cycloalkyl group having 3 to 24 carbon atoms. Specific examples of the cycloalkyl group include cyclopropyl group, cyclopentyl group, cyclohexyl group, methylcyclopentyl group, dimethylcyclopentyl group, methylethylcyclopentyl group, diethylcyclopentyl group, methylcyclohexyl group, dimethylcyclohexyl group, A methyl ethyl cyclohexyl group, a diethyl cyclohexyl group, etc. are mentioned. In addition, the cycloalkyl group may be substituted by the aromatic group, for example, a phenylcyclopentyl group, a phenylcyclohexyl group, etc. are mentioned.

The alkenyl group represented by R ¹ to R ¹² is preferably an alkenyl group having 2 to 30 carbon atoms, and more preferably an alkenyl group having 2 to 24 carbon atoms. As a specific example of an alkenyl group, For example, a vinyl group, an allyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-methylvinyl group, 1-methylallyl group, 1,1-dimethylallyl group, 2-methyl allyl group, nonenyl group, decenyl group, octadecenyl group, etc. are mentioned. In addition, the alkenyl group may be substituted by the aromatic group.

The cycloalkenyl group represented by R ¹ to R ¹² is preferably a cycloalkenyl group having 3 to 30 carbon atoms, and more preferably a cycloalkenyl group having 3 to 24 carbon atoms. As a specific example of a cycloalkenyl group, a cyclobutenyl group, a methylcyclobutenyl group, etc. are mentioned. In addition, the cycloalkenyl group may be substituted by the aromatic group.

The aryl group represented by R ¹ to R ¹² is preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 24 carbon atoms. As a specific example of an aryl group, a phenyl group, tolyl group, xylyl group, naphthyl group, butylphenyl group, octylphenyl group, nonylphenyl group, etc. are mentioned.

In formulas (I) and (II), each Y independently represents —O—, —S—, —SO—, —SO ₂ —, — (C═O) O—, — (C═O) NH—, —O ( C = O) NH-, -C (= O)-, -N (H)-, -NHCONH-, -N = N-, -NH-C (= NH) -NH-, -SC (= O) -, A divalent group selected from -NH-C (= S)-and -NH-C (= S) -NH-.

In general formula (I) and (II), x is an integer of 1-3, 2 is preferable. n is respectively independently an integer of 1-5, 1 or 2 is preferable.

As a sulfur containing compound represented by General formula (I), the compound represented by the following formula is mentioned, for example.

In addition, the following compounds are also mentioned as an example of the compound represented by general formula (I), for example, bis (methoxycarbonylmethyl) disulfide, bis (ethoxycarbonylmethyl) disulfide, bis (n-propoxycarbonylmethyl). Disulfide, bis (isopropoxycarbonylmethyl) disulfide, bis (n-butoxycarbonylmethyl) disulfide, bis (n-octoxycarbonylmethyl) disulfide, bis (n-dodecyloxycarbonyl Methyl) disulfide, bis (cyclopropoxycarbonylmethyl) disulfide, 1,1-bis (2-methoxycarbonylethyl) disulfide, 1,1-bis (3-methoxycarbonyl-n-propyl ) Disulfide, 1,1-bis (4-methoxycarbonyl-n-butyl) disulfide, 1,1-bis (2-ethoxycarbonylethyl) disulfide, 1,1-bis (2-n-pro Foxicarbonylethyl) disulfide, 1, 1-bis (2-isopropoxycarbonylethyl) disulfide, 1, 1-bis (2-cyclopropoxycarbonylethyl) disulfide, etc. are mentioned.

Specific examples of the compound represented by the formula (II) include dithiomal acid tetramethyl, dithiomal acid tetraethyl, dithiomal acid tetra-1-propyl, dithiomal acid tetra-2-propyl, dithiomal acid tetra-1-butyl, and dithi. Tetra-2-butyl, dithiomalic acid tetra isobutyl, dithiomalic acid tetra-1-hexyl, dithiomalic acid tetra-1-octyl, dithiomalic acid tetra-1- (2-ethyl) hexyl, dithiomalic acid Tetra-1- (3,5,5-trimethyl) hexyl, dithiomal acid tetra-1-decyl, dithiomal acid tetra-1-dodecyl, dithiomal acid tetra-1-hexadecyl, dithiomal acid tetra-1 Octadecyl, dithiomalic acid tetrabenzyl, dithiomalic acid tetra-α- (methyl) benzyl, dithiomalic acid tetra-α, α-dimethylbenzyl, dithiomalic acid tetra-1- (2-methoxy) ethyl, dithi Tetramalte-1- (2-ethoxy) ethyl, dithiomalatetetra-1- (2-butoxy) ethyl, dithiomalatetetra-1- (2-ethoxy) ethyl, dithiomalatetetra-1 -(2-butoxy-butox ), And the like, ethyl dithiocarbamic acid tetrahydro-1- (2-phenoxy) acetate.

In this invention, these sulfur containing compounds represented by general formula (I) or (II) may be used individually by 1 type, and 2 or more types may be mixed and used for it. Moreover, 0.01-5.0 mass% is preferable on the basis of a composition whole quantity, and, as for the compounding quantity of this sulfur containing compound, 0.1-2.0 mass% is more preferable. When a compounding quantity is 0.01 mass% or more, sufficient abrasion resistance is obtained and when it exceeds 5.0 mass%, a suitable effect may not be acquired for an addition amount.

[Polar group-containing compound]

In the lubricating oil composition of the present invention, a polar group-containing compound having at least one polar group selected from an amino group, an amide group and a hydroxyl group and an alkyl group having a specific range of carbon atoms is blended.

The polar group-containing compound used in the present invention is a compound having an alkyl group having 3 to 24 carbon atoms, preferably 8 to 20 carbon atoms. When carbon number is less than 3, the solubility of this compound will become low. In addition, although an excellent friction reduction effect is usually obtained with an increase in the number of carbons, if it exceeds 24, it becomes difficult to obtain a suitable effect for increasing the number of carbons.

As said polar group containing compound, the compound selected from the group which consists of a glycerol partial fatty acid ester, a glycerol monoether compound, an amine compound, and an amide compound, and also contains the said alkyl group is mentioned, for example.

The said glycerin partial fatty acid ester is a compound obtained by reaction of glycerin with a fatty acid, for example, acetic acid, propionic acid, butanoic acid (butyric acid), pentanic acid (valeric acid), isopentanic acid (isovaleric acid), Hexanoic acid (caproic acid), heptanoic acid, isoheptanoic acid, octanoic acid (caprylic acid), 2-ethylhexanoic acid, isooctanoic acid, nonanoic acid (pelargonic acid), isononanoic acid, decanoic acid (capric acid) , Isodecanoic acid, undecanoic acid, isoundecanoic acid, dodecanoic acid (lauric acid), isododecaneic acid, tridecanoic acid, isotridecanoic acid, tetradecanoic acid (milistic acid), hexadecanoic acid (palmitic acid) ), Octadecanoic acid (stearic acid), isostearic acid, eicosane (arachinic acid), docosanic acid (behenic acid), tetracoic acid (lignoseric acid), heptaconic acid (serotic acid), octacoic acid (Montanic Acid), 10-Undecenoic Acid, Jomarinic Acid, Oleic Acid, Elide Acid, Linoleic Acid, Linolenic Acid, Gardenic Acid, Erucic Acid And cellolacholeic acid. It may also be a mixed fatty acid obtained by natural fats and oils. Among these fatty acids, from the viewpoint of reducing friction of the lubricating oil, fatty acids having 10 to 18 carbon atoms are preferable, saturated fatty acids having 10 to 12 carbon atoms are more preferable, oleic acid and elic acid are more preferable, and oleic acid is most preferred.

As said glycerin partial fatty acid ester, the glycerin fatty acid monoester represented by following formula (III) and (IV) is mentioned, for example. These compounds can be obtained by the direct esterification reaction of fatty acids and glycerin, the transesterification reaction of fats and oils, and glycerin.

In the general formulas (III) and (IV), each R ¹³ independently represents an alkyl group having 3 to 24 carbon atoms. In the present invention, the glycerin fatty acid monoester represented by the general formula (III) or (IV) may be used alone, or a mixture thereof. In the case of using these glycerin fatty acid monoesters, glycerin fatty acid diesters and glycerin fatty acid triesters may be mixed.

The said glycerin monoether compound is a compound obtained by reaction of glycerin and an aliphatic alcohol, for example, propanol, butanol, oleyl alcohol, stearyl alcohol, etc. are mentioned. Among them, oleyl alcohol and stearyl alcohol are preferred from the viewpoint of friction reduction of lubricating oil, and oleyl alcohol is particularly preferable.

As said glycerin monoether compound, the glycerin monoether compound represented by following formula (V) and VI is mentioned, for example.

In the formulas (V) and (VI), each R ¹⁴ independently represents an alkyl group having 3 to 24 carbon atoms, and in the present invention, a glycerin monoether compound represented by the formula (V) or (VI) may be used alone, or a mixture thereof. In addition, when using these glycerin monoether compounds, the glycerin diether and the glycerin triether may be mixed.

As said amine compound, an alkylamine compound and an alkanolamine compound are mentioned, for example. As an alkyl group in an alkylamine compound, the alkyl group contained in the said fatty acid is mentioned. As this amine compound, the amine compound represented by following General formula (VII) is mentioned, for example.

In formula (VII), R ¹⁵ represents an alkyl group having 3 to 24 carbon atoms, and R ¹⁶ each independently represents a group in which a terminal hydrogen atom of a hydrogen atom or a linear alkyl group having 2 to 4 carbon atoms is substituted with a hydroxyl group [for example,-( CH ₂ ) ₂ —OH], and in the present invention, the amine compound represented by the formula (VII) may be used alone or in a mixture.

Specific examples of the amine compound include monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N, N-dimethylethanolamine, N-ethylethanolamine, N, N-diethylethanolamine, and N-iso Propylethanolamine, N, N-diisopropylethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-methylisopropanolamine, N, N-dimethylisopropanolamine, N-ethylisopropanolamine, N, N- Diethylisopropanolamine, N-isopropylisopropanolamine, N, N-diisopropylisopropanolamine, monon-propanolamine, din-propanolamine, trin-propanolamine, N-methyln-propanolamine, N, N-dimethyl n-propanolamine, N-ethyln-propanolamine, N, N-diethyln-propanolamine, N-isopropyln-propanolamine, N, N-diisopropyln-propanolamine, monobutanol Amine, dibutanolamine, tributanolamine, N-methyl moiety There may be mentioned all-amine, N, N- dimethyl-butanol amine, N- ethyl-butanol amine, N, N- diethyl-butanol amine, N- isopropyl-butanol amine, N, N- diisopropyl amine, such as butanol.

As said amide compound, the compound obtained by making 1- tetravalent carboxylic acid, alkylamine, or alkanolamine react is mentioned.

As an alkyl group which comprises the said monovalent carboxylic acid, for example, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group , Heptadecyl, octadecyl, nonadecyl, isocyl, pentacosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl and A triacontyl group, etc. are mentioned.

Examples of the monovalent carboxylic acid include caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachinic acid, behenic acid, and lignoseric acid. As polyhydric carboxylic acid, polycarboxylic acid, such as oxalic acid, a phthalic acid, trimellitic acid, a pyromellitic acid, is mentioned.

As said amide compound, the amide compound represented by following formula (VIII) is mentioned, for example.

In formula (VIII), R ¹⁷ represents an alkyl group having 3 to 24 carbon atoms, and R ¹⁸ each independently represents a group in which a terminal hydrogen atom of a hydrogen atom or a straight alkyl group having 2 to 4 carbon atoms is substituted with a hydroxyl group [for example,-(CH ₂ ) ₂ -OH]. In the present invention, the amide compound represented by the formula (VIII) may be used alone or in a mixture.

Specific examples of the amide compound include oleic acid monoethanolamide, oleic acid diethanol amide, oleic acid monopropanolamide, oleic acid dipropanolamide and the like.

The polar group-containing compound in the present invention may be a compound obtained by the reaction between the polar group-containing compound and the molybdenum compound. As this molybdenum compound, molybdenum oxide, molybdenum halide, molybdate acid, etc. are mentioned, for example. In this reaction, the molybdenum compound is preferably used in a molar ratio of 0.01 to 10 moles, more preferably 0.05 to 5 moles per mole of the polar group-containing compound.

In the said reaction, a solvent, for example, organic solvents, such as a hydrocarbon oil, hexane, heptane, an octane, toluene, xylene, can be used.

Although the reaction temperature of the said reaction does not have a restriction | limiting in particular, Preferably it is 50-250 degreeC, More preferably, it is 100-200 degreeC.

The polar group containing compound in this invention may be a compound obtained by reaction of the said polar group containing compound and a boron compound. Examples of the boron compound include boron oxide, boron halide, boric acid, boric anhydride, boric acid ester, and the like. In this reaction, the boron compound is preferably used in a molar ratio of 0.01 to 10 moles, more preferably 0.05 to 5 moles per mole of the polar group-containing compound.

In the said reaction, a solvent, for example, organic solvents, such as a hydrocarbon oil, hexane, heptane, an octane, toluene, xylene, can be used.

Although the reaction temperature of the said reaction does not have a restriction | limiting in particular, Preferably it is 50-250 degreeC, More preferably, it is 100-200 degreeC.

In this invention, a polar group containing compound may be used individually by 1 type, and 2 or more types may be mixed and used for it. Moreover, 0.01-5.0 mass% is preferable on the basis of a composition whole quantity, and, as for the compounding quantity of a polar group containing compound, 0.1-2.0 mass% is more preferable. When the compounding amount is 0.01% by mass or more, a sufficient friction reducing effect is obtained, and when the amount is 5.0% by mass or more, the dissolved residue may occur.

In the lubricating oil composition of this invention, you may mix | blend a conventionally well-known additive in the range which does not inhibit the effect. Examples of the additive include antioxidants, ashless dispersants, metal cleaners, viscosity index improvers, pour point depressants, metal deactivators, rust inhibitors and antifoaming agents.

As said antioxidant, antioxidant which does not contain phosphorus is preferable, For example, a phenolic antioxidant, an amine antioxidant, a molybdenum amine complex system antioxidant, sulfur type antioxidant, etc. are mentioned.

As a phenolic antioxidant, 4,4'- methylenebis (2,6-di-t-butylphenol), 4,4'-bis (2,6-di-t-butylphenol), 4,4, for example '-Bis (2-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6- t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 4,4'-isopropylidenebis (2,6-di-t-butylphenol), 2,2'-methylenebis (4-methyl-6-nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl-6- Cyclohexylphenol), 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4-dimethyl-6-t-butylphenol, 2, 6-di-t-amyl-p-cresol, 2,6-di-t-butyl-4- (N, N'-dimethylaminomethylphenol), 4,4'-thiobis (2-methyl-6- t-butylphenol), 4,4'-thiobis (3-methyl-6-t-ë-tylphenol), 2,2'-thiobis (4-methyl-6-t-butylinol), bis (3- Methyl-4-hydroxy-5-t-butylbenzyl) sulfide, bis (3,5-di-t-butyl-4-hydroxybenzyl) sulfide, n-octyl-3- (4-hydroxy -3,5-di-t-butylphenyl) propionate, n-octadecyl-3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, 2,2'-thio [Diethyl-bis-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] etc. are mentioned.

Among these, it is especially preferable that they are bisphenol type and ester group containing phenol type.

Moreover, as said amine antioxidant, For example, Monoalkyl diphenylamine type, such as monooctyl diphenylamine and monononyl diphenylamine; 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine Dialkyl diphenylamines such as 4,4'-dinonyldiphenylamine; Tetrabutyldiphenylamine, tetrahexyldiphenylamine; Polyalkyldiphenylamines such as tetraoctyldiphenylamine and tetranonyldiphenylamine; And α-naphthylamine, phenyl-α-naphthylamine, but also butylphenyl-α-naphthylamine, pentylphenyl-α-naphthylamine, hexylphenyl-α-naphthylamine, heptylphenyl-α-naphthyl And alkyl substituted phenyl-α-naphthylamines such as amines, octylphenyl-α-naphthylamine and nonylphenyl-α-naphthylamine.

It is preferable that they are dialkyl diphenylamine type and naphthylamine type among these.

As said molybdenum amine complex antioxidant, it is made by reacting a hexavalent molybdenum compound, specifically molybdenum trioxide and / or molybdate acid, and an amine compound, for example by the manufacturing method of Unexamined-Japanese-Patent No. 2003-252887. The compound obtained can be used.

Although it does not restrict | limit especially as an amine compound made to react with the said hexavalent molybdenum compound, Specifically, a monoamine, a diamine, a polyamine, and an alkanolamine are mentioned. More specifically, Alkylamine which has a C1-C30 alkyl group (These alkyl groups may be linear or branched), such as methylamine, ethylamine, dimethylamine, diethylamine, methylethyl amine, and methylpropylamine; Alkenylamines having alkenyl groups having 2 to 30 carbon atoms (the alkenyl groups may be linear or branched) such as ethenylamine, propenylamine, butenylamine, octenylamine and oleylamine; Alkanolamines having an alkanol group having 1 to 30 carbon atoms (these alkanol groups may be linear or branched) such as methanol amine, ethanol amine, methanol ethanol amine and methanol propanol amine; Alkylenediamines having an alkylene group having 1 to 30 carbon atoms such as methylenediamine, ethylenediamine, propylenediamine and butylenediamine; Polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine; An alkyl group having 8 to 20 carbon atoms or alkenyl to the above monoamines, diamines, and polyamines, such as undecyldiethylamine, undecyldiethanolamine, dodecyldipropanolamine, oleyl diethanolamine, oleylpropylenediamine, and stearyltetraethylenepentamine Heterocyclic compounds such as a compound having a group and imidazoline; Alkylene oxide adducts of these compounds; And these mixture etc. can be illustrated.

Moreover, the sulfur containing molybdenum complex of the succinic acid imide described in Unexamined-Japanese-Patent No. 3-22438 and Unexamined-Japanese-Patent No. 2004-2866 can be illustrated.

Examples of the sulfur-based antioxidant include phenothiazine, pentaerythritol-tetrakis- (3-laurylthiopropionate), dododecyl sulfide, dioctadecyl sulfide, didodecylthiodipropionate, dioctade Silthiodipropionate, dimyristyl thiodipropionate, dodecyl octadecyl thiodipropionate, 2-mercaptobenzoimidazole, and the like.

Among these antioxidants, phenolic antioxidants and amine antioxidants are preferable from the viewpoint of reducing metal powder and sulfur powder. In addition, the said antioxidant may be used individually by 1 type, and may mix and use 2 or more types. Among these, from the viewpoint of the effect of oxidation stability, a mixture of one or two or more phenolic antioxidants and one or two or more amine antioxidants is preferable.

The range of 0.1-5 mass% is preferable on the basis of a composition whole quantity, and, as for the compounding quantity of antioxidant, the range of 0.1-3 mass% is more preferable.

As the ashless dispersant, any ashless dispersant used for lubricating oil can be used, but for example, a mono-type succinic acid imide compound represented by the following general formula (IX) or a bis-type succinic acid imide represented by the following general formula (X) The compound can be mentioned.

In Formulas IX and X, R ¹⁹ , R ^21, and R ²⁴ each represent an alkenyl group or alkyl group having a number average molecular weight of 500 to 4,000, and R ²¹ and R ²⁴ may be the same or different, and R ¹⁹ , R ^21, and The number average molecular weight of R ²⁴ is preferably 1,000 to 4,000.

Wherein R ^19, R ²¹ and R ²⁴ is a number-average molecular weight of not less than 500, it is excellent in solubility in a base oil, and 4,000 minutes or less there is no danger of acid is decreased.

R ²⁰ , R ²² and R ²³ are each an alkylene group having 2 to 5 carbon atoms, R ²² and R ²³ may be the same or different, r represents an integer of 1 to 10, and s is 0 or 1 to 1 The integer of 10 is shown. Also, the r is preferably 2 to 5, more preferably 3 to 4. Dispersibility is favorable when r is 1 or more, and solubility to base oil is also favorable when r is 10 or less.

In the formula (X), s is preferably 1 to 4, more preferably 2 to 3. If s is in the range of 1-4, it is preferable at the point of dispersibility and solubility to base oil.

As said alkenyl group, a polybutenyl group, a polyisobutenyl group, and an ethylene-propylene copolymer are mentioned, As an alkyl group, these are hydrogenated. As a representative example of a preferable alkenyl group, a polybutenyl group or a polyisobutenyl group is mentioned. The polybutenyl group is obtained by polymerizing a mixture of 1-butene and isobutene or isobutene of high purity.

Moreover, the typical example of a preferable alkyl group is hydrogenated polybutenyl group or polyisobutenyl group.

The alkenylsuccinic acid imide compound or the alkyl succinic acid imide compound can generally be produced by reacting an alkenylsuccinic anhydride obtained by reaction of a polyolefin with maleic anhydride or an alkyl succinic anhydride obtained by hydrogenation thereof with a polyamine. The mono-type succinic acid imide compound and the bis-type succinic acid imide compound can be produced by changing the reaction ratio of the alkenylsuccinic anhydride or alkyl succinic anhydride and polyamine.

As an olefin monomer which forms the said polyolefin, although 1 type (s) or 2 or more types of C2-C8 alpha olefin can be mixed and used, the mixture of isobutene and butene-1 can be used preferably.

Moreover, as said polyamine, Single diamine, such as ethylenediamine, propylenediamine, butylenediamine, pentylenediamine; Polyalkylenes such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di (methylethylene) triamine, dibutylenetriamine, tributylenetetramine, pentapentylenehexamine Polyamines; Piperazine derivatives, such as amino ethyl piperazine, etc. are mentioned.

As the ashless dispersant, in addition to the alkenyl or alkyl succinic acid imide compounds, boron derivatives thereof and / or those modified with organic acids can also be used.

The boron derivative of an alkenyl or alkyl succinic acid imide compound can use the thing manufactured by the conventional method. For example, the polyolefin is reacted with maleic anhydride to form alkenylsuccinic anhydride, and then the polyamine and boron compounds such as boron oxide, boron halide, boric acid, boric anhydride, boric acid ester, and ammonium salt of boric acid are reacted. It is obtained by making it imidize by making it react with the obtained intermediate.

Although there is no restriction | limiting in particular in the boron content in this boron derivative, As boron, Preferably it is the range of 0.05-5 mass%, More preferably, it is the range of 0.1-3 mass%.

In addition, the amount of the ashless dispersant is preferably in the range of 0.5 to 15% by mass, more preferably in the range of 1 to 10% by mass, still more preferably in the range of 3 to 7% by mass, based on the total amount of the lubricating oil composition.

When the compounding amount is less than 0.5% by mass, the base under high temperature has little effect on the retention, while when the amount exceeds 15% by mass, the low-temperature fluidity of the lubricating oil composition is greatly deteriorated, which is not preferable.

As the metal-based cleaning agent, any alkaline earth metal-based cleaning agent used for lubricating oil can be used, and for example, alkaline earth metal sulfonate, alkaline earth metal phenate, alkaline earth metal salicylate and mixtures of two or more selected from these, etc. Can be mentioned.

As the alkaline earth metal sulfonate, preferably an alkaline earth metal salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a molecular weight of preferably 300 to 1,500, more preferably 400 to 700, in particular magnesium salt and / or calcium salt, etc. And calcium salts are used preferably.

Examples of the alkaline earth metal phenate include alkali earth metal salts, especially magnesium salts and / or calcium salts of Mannich reactants of alkylphenols, alkylphenol sulfides and alkylphenols, and calcium salts are particularly preferably used.

Examples of the alkaline earth metal salicylate include alkaline earth metal salts of alkyl salicylic acid, in particular magnesium salts and / or calcium salts, among which calcium salts are preferably used.

As an alkyl group which comprises the said alkaline-earth metal type detergent, it is preferable that it is C4-C30, More preferably, it is a 6-18 group or branched alkyl group, These may be linear or branched.

They may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

In addition, as alkaline earth metal sulfonate, alkaline earth metal phenate, and alkaline earth metal salicylate, the above-mentioned alkyl aromatic sulfonic acid, alkylphenol, alkylphenol sulfide, Mannich reactant of alkylphenol, alkyl salicylic acid, etc. can be directly added to magnesium and A neutral alkaline earth metal sulfonate obtained by reacting with an alkaline earth metal base such as an oxide or hydroxide of an alkaline earth metal of calcium or an alkali metal salt such as sodium salt or potassium salt and then replacing the alkaline earth metal salt with Not only neutral alkaline earth metal phenates and neutral alkaline earth metal salicylates, but also neutral alkaline earth metal sulfonates, neutral alkaline earth metal phenates and neutral alkaline earth metal salicylates and excess alkaline earth metal salts or alkaline earth metal bases In the presence of water Basic alkaline earth metal sulfonates, basic alkaline earth metal phenates and basic alkaline earth metal salicylates obtained by heating, neutral alkaline earth metal sulfonates, neutral alkaline earth metal phenates and neutral alkaline earth metal salins in the presence of carbon dioxide gas Also included are overbased alkaline earth metal sulfonates, overbased alkaline earth metal phenates and overbased alkaline earth metal salicylates obtained by reacting the silates with carbonates or borates of alkaline earth metals.

As the metal-based cleaning agent used in the present invention, alkaline earth metal salicylates and alkaline earth metal phenates are preferred for the purpose of reducing the sulfur content in the composition, and among these, overbased salicylates and overbased phenates are particularly preferred. Overbased calcium salicylates are preferred.

The total base value of the metallic detergent used in the present invention is preferably in the range of 10 to 500 mgKOH / g, more preferably in the range of 15 to 450 mgKOH / g, and may be used in combination of one or two or more selected from these.

In addition, all-base value here means all-base value by the potentiometric titration method (base-perchloric acid method) measured based on 7. of JISK2501 "petroleum product and lubricating oil-neutralization test method."

In addition, as a metal type cleaning agent used in this invention, there is no restriction | limiting in particular in the metal ratio, Usually, 20 or less types can be used 1 type or in mixture of 2 or more types, Preferably, metal ratio is 3 or less, More preferably, 1.5 Hereinafter, it is particularly preferable to use a metallic detergent of 1.2 or less because it is excellent in oxidative stability, base stability, high temperature cleanability, and the like.

In addition, the metal ratio here is represented by (the valence of a metal element) x (metal element content (mol%)) / (soap content (mol%)) in a metal type detergent, and a metal element is calcium, magnesium, etc. The soap group means a sulfonic acid group, a phenol group and a salicylic acid group.

As for the compounding quantity of the said metal type cleaning agent, the range of 0.01-20 mass% is preferable on the basis of the lubricating oil composition whole quantity, The range of 0.1-10 mass% is more preferable, The range of 0.5-5 mass% is further more preferable.

When the compounding amount is less than 0.01% by mass, it is not preferable because performances such as high temperature cleanliness, oxidative stability, and base stability are difficult to obtain. On the other hand, if it is 20 mass% or less, a moderate effect can normally be acquired with the addition amount, but it is important to make a compounding quantity as low as possible about the upper limit of the compounding quantity of the said metal type cleaning agent irrespective of said range. Thereby, metal powder, ie, sulfuric acid ash of a lubricating oil composition can be reduced, and deterioration of the exhaust gas purification apparatus of an automobile can be prevented.

In addition, a metallic detergent contains only the said prescribed amount and can also be used individually or in combination of 2 or more types.

Specifically, in the metal-based detergent, overbased calcium salicylate or overbased calcium phenate is particularly preferable in the ashless dispersant. The total base value of the overbased calcium salicylate and overbased calcium phenate is preferably in the range of 100 to 500 mgKOH / g, more preferably in the range of 200 to 500 mgKOH / g.

Examples of the viscosity index improver include polymethacrylates, dispersed polymethacrylates, olefin copolymers (for example, ethylene-propylene copolymers), dispersed olefin copolymers, and styrene copolymers (for example, For example, a styrene diene copolymer, a styrene isoprene copolymer, etc. can be mentioned.

From the viewpoint of the blending effect, the blending amount of the viscosity index improver is preferably in the range of 0.5 to 15 mass%, more preferably in the range of 1 to 10 mass%.

Examples of the pour point depressant include polymethacrylate having a weight average molecular weight of about 5000 to 50,000.

From the viewpoint of the blending effect, the blending amount of the pour point lowering agent is preferably in the range of 0.1 to 2% by mass, more preferably in the range of 0.1 to 1% by mass, based on the total amount of the lubricating oil composition.

As said metal deactivator, a benzotriazole type, tolyl triazole type, a thiadiazole type, an imidazole type compound, etc. are mentioned, for example.

As for the compounding quantity of a metal deactivator, the range of 0.01-3 mass% is preferable on the basis of the lubricating oil composition whole quantity, More preferably, it is the range of 0.01-1 mass%.

As said rust inhibitor, a petroleum sulfonate, alkylbenzene sulfonate, dinonyl naphthalene sulfonate, alkenyl succinic acid ester, polyhydric alcohol ester, etc. are mentioned, for example.

From the viewpoint of the blending effect, the blending amount of these rust inhibitors is preferably in the range of 0.01 to 1% by mass, more preferably in the range of 0.05 to 0.5% by mass.

Examples of the antifoaming agent include silicone oil, fluoro silicone oil, fluoroalkyl ether, and the like, and the compounding amount is 0.005 to 0.5% by mass based on the total amount of the lubricating oil composition in view of the balance of defoaming effect and economic efficiency. A range is preferable, More preferably, it is the range of 0.01-0.2 mass%.

In the lubricating oil composition of this invention, you may mix | blend a friction modifier, an antiwear agent, and an extreme pressure agent further as needed. In addition, this friction modifier points out compounds other than the polar group containing compound which is an essential component of this invention. As for the compounding quantity of a friction modifier, the range of 0.01-2 mass% is preferable on the basis of the lubricating oil composition whole quantity, More preferably, it is the range of 0.01-1 mass%.

Examples of the antiwear or extreme pressure agent include zinc dithiophosphate, zinc phosphate, zinc dithiocarbamate, molybdenum dithiocarbamate, molybdenum dithiophosphate, and disulfides (sulfur-containing represented by the formula (I) or (II) used in the present invention). Points other than a compound are mentioned, for example, dibenzyl disulfide). Sulfur-containing compounds such as sulfided olefins, sulfurized fats and oils, sulfided esters, thiocarbonates, thiocarbamates and polysulfides; Phosphorus-containing compounds such as phosphite esters, phosphate esters, phosphonic acid esters, and these amine salts and metal salts; Sulfur and phosphorus containing antiwear agents, such as thiophosphoric acid ester, thiophosphoric acid ester, thiophosphonic acid ester, these amine salt, or a metal salt, etc. are mentioned.

When mix | blending an antiwear agent or extreme pressure agent, it is necessary to care about the compounding quantity so that content of phosphorus, sulfur, and metal powder in lubricating oil by mix | blending an antiwear agent or extreme pressure agent may not become excessive.

Although the lubricating oil composition of this invention consists of said composition, it is preferable to satisfy the following as a property.

(1) sulfuric acid ash (JIS K2272) is 0.6 mass% or less, more preferably 0.1 mass% or less, and

(2) Phosphorus content (JIS-5S-38-92) is 0.5 mass% or less, More preferably, it is 0 mass%.

Moreover, it is more preferable to satisfy the followings other than the above.

(3) Sulfur content (JIS K2541) is 0.4 mass% or less, More preferably, it is 0.2 mass% or less.

(4) Boron content is 0.4 mass% or less, More preferably, it is 0.2 mass% or less.

The lubricating oil composition of the present invention, which satisfy these properties can be prevented from being deteriorated such as a car engine an oxidation catalyst, three-way catalysts, NO _x occlusion type reducing catalyst, a diesel particulate filter (DPF).

The lubricating oil composition of the present invention uses a combination of the sulfur-containing compound and the polar group-containing compound, and as a result of this combination, it exhibits abrasion resistance and friction reducing effect far exceeding each use alone. Therefore, a lubricating oil composition having sufficiently good lubricating performance can be obtained without blending zinc dithiophosphate, which has conventionally been frequently used as a lubricating oil additive, and it becomes easy to achieve properties such as sulfuric acid ash. Moreover, as mentioned later, the lubricating oil composition of this invention shows the outstanding friction reduction effect also when using for the sliding part which performed the DLC process.

Since the lubricating oil composition of this invention can be used suitably as lubricating oil for internal combustion engines, such as gasoline engines, diesel engines, and gas engines, such as a two-wheeled vehicle, a four-wheeled vehicle, power generation, and a ship, and since it is low phosphorus, low sulfur, and low sulfuric acid ash, It is especially suitable for the internal combustion engine equipped with the exhaust gas purification apparatus.

Moreover, the lubricating oil composition of this invention is used suitably also in the use of that excepting the above. In particular, since the lubricating oil composition of the present invention exhibits excellent wear resistance and friction reducing effect, for example, an internal combustion engine, an automatic transmission, a continuously variable transmission, a manual transmission, a power steering, a shock absorber, a compressor, a refrigerant compressor, a refrigerator, a hydraulic pump, and Used for lubrication of clutch pulleys. That is, the lubricating oil composition of the present invention includes an internal combustion engine oil, an automatic transmission oil, a continuously variable transmission oil, a manual transmission oil, a power steering oil, a shock absorber oil, a compressor oil, a freezer oil, a hydraulic pump oil, a lubricant for a clutch pulley, grease and the like. Can be used.

The lubricating oil composition of the present invention exhibits a friction reducing effect and excellent wear resistance not only when the sliding surface is a metal such as steel, but also when the sliding surface has a DLC film on at least part of the sliding surface.

From the viewpoint of enhancing the friction reducing effect, the DLC film preferably has a hydrogen content of 40 atomic% or less, more preferably 30 atomic% or less, and particularly preferably 20 atomic% or less.

There is no restriction | limiting in particular about the relative member of the sliding member which has a DLC film | membrane in a sliding surface, For example, it may be a sliding member which has a DLC film | membrane similarly, or may be an organic material, such as iron, an iron alloy member, an aluminum alloy member, resin, or a rubber material have.

 <Examples>

Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

 <Method of measuring appearance, performance>

The properties and the performance of the lubricating oil composition in the following examples and comparative examples were determined by the following method.

(1) kinematic viscosity

It measured based on JISK2283.

(2) phosphorus content

It measured based on JPI-5S-38-92.

(3) sulfur content

It measured based on JISK2541.

(4) boron content

It measured based on JPI-5S-38-92.

(5) sulfuric acid ash

It measured based on JISK2272.

(6) Reciprocating friction test

In the reciprocating friction tester, the test was performed under the following conditions as a test plate and a test tool, and the friction coefficient was obtained.

 ? Trial: SUJ-2

 ? Test sphere: 1/2 inch sphere made of SUJ-2 treated with DLC (hydrogen content: 20%)

 [Exam conditions]

 ? Test temperature: 100 ℃

 ? Load: 200g

 ? Amplitude: 10mm

 ? Sliding Speed: 1.0mm / sec

(7) friction wear test

In the reciprocating friction tester, the test was performed under the following conditions as a test plate and a test tool, and the wear mark width of the test plate was measured.

 ? Trial: SUJ-2

 ? Test mouth: sphere made of SUJ-2 (diameter 10mm)

[Exam conditions]

 ? Test temperature: 100 ℃

 ? Load: 200 N

 ? Amplitude: 10 mm

 ? Frequency: 10 Hz

 ? Test time: 30 minutes

Examples 1 to 7, Comparative Examples 1 to 9

The base oil and additive shown in the 1st table were mix | blended in the ratio shown in a 1st table, and the lubricating oil composition was produced. The properties, compositions and performances of the composition are shown in the first table.

[week]

Base oil: Hydrogenated refined base oil, 40 ℃ kinematic viscosity 21 mm2 / s, 100 ℃ kinematic viscosity 4.5 mm2 / s, viscosity index 127,% C _A 0.0, sulfur content less than 20 mass ppm, NOACK evaporation 13.3 mass%

 ? Sulfur-containing compound A: 1,1-bis (octoxycarbonylmethyl) disulfide

 ? Sulfur-containing compound B: dithiomalate tetra-1-hexyl

 ? Polar group-containing compound A: glycerin monooleate

 ? Polar group-containing compound B: oleic acid diethanol amide

 ? Polar group-containing compound C: glycerin monooleyl ether

 ? Polar group-containing compound D: N, N-dipolyoxyethylene-N-oleyl amine

 ? Polar group-containing compound E: reaction product of glycerin monooleate with boric acid

 ? Polar group-containing compound F: reaction product of oleic acid diethanol amide with boric acid

 ? Viscosity index improver: Polymethacrylate, weight average molecular weight 420,000, resin amount 39 mass%

 ? Pour point depressant: Polyalkyl methacrylate, weight average molecular weight 6,000

 ? Polybutenyl succinic acid imide: Number average molecular weight 1000 of a polybutenyl group, 1.76 mass% of nitrogen content, 1.9 mass% of boron content

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

 Amine-based antioxidants: dialkyldiphenylamine, nitrogen content 4.62 mass%

 Zinc dialkyl dithiophosphate: Zn content 9.0 mass%, phosphorus content 8.2 mass%, sulfur content 17.1 mass%, alkyl group (mixture of secondary butyl group and secondary hexyl group)

 Others: defoamer, metal deactivator

As shown in the first and second tables, the lubricating oil compositions of Examples 1 to 7 exhibit low friction coefficient and low wear mark diameter values due to the synergistic effect of the combination of the sulfur-containing compound and the polar group-containing compound. have.

That is, in Comparative Example 1 having no polar group-containing compound, the friction coefficient was 0.140. In Comparative Examples 2 to 7, which did not have sulfur-containing compound, the friction coefficient was 0.110 to 0.117 by combining them even though the friction coefficient was 0.124 to 0.128. It can be reduced to (Examples 1 to 7). In addition, in Comparative Example 1 having no polar group-containing compound, the wear mark diameter value was 0.52. In Comparative Examples 2 to 7, which did not have a sulfur-containing compound, the wear mark diameter was combined by combining them despite the 0.60 to 0.65 wear mark diameter. The diameter value can be reduced to 0.42 to 0.46 (Examples 1 to 7).

In addition, as can be seen from the comparison between Examples 1 to 7 and Comparative Example 8, the effect expressed by the use of the additive of the present invention is greater than the effect of combining zinc dialkyldithiophosphate alone. will be. In addition, as shown in Comparative Example 9, even when used in combination with the polar group-containing compound using zinc dialkyldithiophosphate instead of the sulfur-containing compound used in the present invention, low friction coefficient and low wear marks as shown in Examples 1 to 7 The diameter value is not obtained.

By using a specific sulfur-containing compound and a specific polar group-containing compound as described above, the wear resistance of zinc dialkyldithiophosphate can be exceeded. As a result, a lubricating oil composition excellent in wear resistance even as low phosphorus, low sulfur and low sulfuric acid ash As the lubricant composition, an excellent friction reducing effect can be obtained.

 Industrial Applicability

According to the present invention, there is provided a lubricating oil composition exhibiting excellent friction reducing effect even when used as a lubricating oil composition excellent in wear resistance even in low phosphorus, low sulfur powder and low sulfuric acid ash. Therefore, the lubricating oil composition of this invention can be used especially preferably as a lubricating oil composition for internal combustion engines, such as a gasoline engine, a diesel engine, and a gas engine.

Claims (7)

Base oil,
(A) at least one selected from sulfur-containing compounds represented by the following formulas (I) and (II),
(B) a polar group-containing compound having at least one polar group selected from an amino group, an amide group and a hydroxyl group and an alkyl group having 3 to 24 carbon atoms
Lubricating oil composition formed by blending.

(R ¹ to R ¹² are each independently a hydrogen atom; a hydrocarbon group selected from an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group and an aryl group; or an atom selected from an oxygen atom, a nitrogen atom and a sulfur atom in these hydrocarbon groups) And a hetero atom-containing group comprising a compound, and each Y independently represents -O-, -S-, -SO-, -SO ₂ -,-(C = O) O-,-(C = O) NH-, -O (C = O) NH-, -C (= O)-, -N (H)-, -NHCONH-, -N = N-, -NH-C (= NH) -NH-, -SC ( = O)-, -NH-C (= S)-and -NH-C (= S) -NH- represent a divalent group selected, x is an integer of 1 to 3, n is each independently 1 to Is an integer of 5) The polar group-containing compound according to claim 1, wherein the polar group-containing compound having at least one polar group selected from the amino group, the amide group and the hydroxyl group and an alkyl group having 3 to 24 carbon atoms is a glycerin partial fatty acid ester, a glycerin monoether compound, or an amine compound. And at least one compound selected from the group consisting of amide compounds. The glycerin fatty acid monoester according to claim 1, wherein the (B) polar group-containing compound having at least one polar group selected from an amino group, an amide group and a hydroxyl group and an alkyl group having 3 to 24 carbon atoms is represented by the following general formula (III) or (IV): Or a glycerol monoether compound represented by the following formula (V) or (VI).

(R ¹³ and R ¹⁴ each independently represent an alkyl group having 3 to 24 carbon atoms) The polar group-containing compound according to claim 1, wherein the polar group-containing compound having at least one polar group selected from the amino group, the amide group and the hydroxyl group and an alkyl group having 3 to 24 carbon atoms is represented by the amine compound represented by the following general formula (VII) or the general formula (VIII) The lubricating oil composition which is an amide compound shown.

(R ¹⁵ and R ¹⁷ each independently represent an alkyl group having 3 to 24 carbon atoms, and R ¹⁶ and R ¹⁸ each independently represent a group in which a terminal hydrogen atom of a hydrogen atom or a straight chain alkyl group having 2 to 4 carbon atoms is substituted with a hydroxyl group) The lubricating oil composition of any one of Claims 1-4 whose phosphorus content is 0.5 mass% or less and sulfuric acid ash 0.6 mass% or less on the basis of the lubricating oil composition whole quantity. The lubricating oil composition of any one of Claims 1-5 whose phosphorus content is 0 mass% and sulfuric acid ash content of 0.1 mass% or less on the basis of the lubricating oil composition whole quantity. The lubricating oil composition according to any one of claims 1 to 6, which is a lubricating oil composition for a sliding part subjected to a diamond-like carbon (DLC) treatment.