JP5186523B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition.

  In recent years, as a part of energy saving measures, a new type of turbine device equipped with a speed increasing gear device that uses generated by-product gas as fuel has been developed and is being introduced to steelworks and the like. By-product gas, which is the fuel of the device, has a heat quantity as low as about one-tenth of that of conventionally used heavy oil fuel, etc., so that it is sufficient to rotate the turbine and generate power efficiently by simply burning it. Can't get the power. In order to obtain a necessary force from the byproduct gas, it is essential to increase the expansion force during combustion by highly compressing the gas. For this reason, the apparatus is further provided with a gas compressor for compressing the by-product gas and a speed increasing gear device for further compressing. The installed speed increasing gear unit directly connects the gas compressor and the turbine shaft. For the purpose of downsizing the turbine unit, the turbine shaft lubricating oil and the speed increasing gear unit lubricating oil are combined. It is required to be used. Such lubricating oil is required to have the performance of both turbine oil and gear oil. In particular, it is required to have excellent sludge resistance performance and high extreme pressure properties under severe conditions of high temperature and high surface pressure.

JP-A-4-359994

  However, it cannot be said that the conventional lubricating oil has sufficient sludge resistance and extreme pressure when used in the above-described speed increasing gear device. That is, for applications that require high extreme pressure and wear resistance, lubricating oils with added sulfur-based extreme pressure agents such as zinc dialkyldithiophosphate are widely used. Even if the amount is small, if a heat load is applied, a large amount of sludge is generated and the thermal / oxidation stability tends to be lowered. Therefore, it is difficult for the lubricating oil to which the sulfur-based extreme pressure agent is added to achieve sufficient thermal and oxidation stability in the above-described speed increasing gear device. On the other hand, phosphorus-based extreme pressure agents tend to generate less sludge than sulfur-based extreme pressure agents. However, when a phosphorus-based extreme pressure agent is used alone, high extreme pressure characteristics at the gear oil level can be obtained. Is difficult.

  The present invention has been made in view of such circumstances, and has a sufficiently long oxidation life even when used in a speed increasing gear device or the like that is operated in a severe environment of high temperature and high surface pressure. An object of the present invention is to provide a lubricating oil composition capable of achieving a high level of sludge resistance and extreme pressure resistance.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above-mentioned problems can be solved by incorporating a phosphorus-containing carboxylic acid compound, a phosphorus compound and a specific antioxidant into a predetermined base oil. The headline and the present invention were completed.

That is, the lubricating oil composition of the present invention comprises at least one base oil selected from esters of a polyhydric alcohol and a fatty acid having 5 to 9 carbon atoms, a phosphorus-containing carboxylic acid compound, a phosphate ester, and acidic phosphoric acid. A phosphorus compound which is at least one selected from esters, amine salts of acidic phosphates, chlorinated phosphates and phosphites, and at least one selected from alkylphenols and aromatic amines. Features.

  According to the lubricating oil composition of the present invention, even when used in a speed increasing gear device operated under a severe environment of high temperature and high surface pressure, it exhibits a sufficiently long oxidation life and a high level. Sludge resistance and extreme pressure resistance can be achieved. Therefore, the lubricating oil composition of the present invention is very useful in terms of suppressing wear of sliding parts in a speed increasing gear device and the like and extending the life of the device.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description, when a compound or a functional group can take both a linear structure and a branched structure, the compound includes both a linear structure and a branched structure unless otherwise specified. It is.

  The lubricating oil composition of the present invention contains at least one base oil selected from esters of polyhydric alcohols and fatty acids having 2 to 24 carbon atoms.

  As mineral oil, for example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing And oils such as paraffinic and naphthenic oils purified by appropriately combining purification treatments such as clay treatment. Further, it is also possible to use a wax isomerized mineral oil, a base oil produced by a method of isomerizing GTL WAX (Gas Liquid Wax), or the like.

  Examples of the synthetic oil include polyolefin, alkylbenzene, alkylnaphthalene, ester, polyoxyalkylene glycol, polyphenyl ether, dialkyldiphenyl ether, fluorine-containing compounds (perfluoropolyether, fluorinated polyolefin, etc.), silicone oil and the like.

  Examples of the fats and oils include beef tallow, lard, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil and other animal and vegetable oils, and hydrogenated products thereof.

  Among these base oils, it is more heat resistant. Because of excellent heat and oxidation stability, it is preferable to use mineral oil, polyolefin, and ester that have been subjected to hydrogenation treatment or the like to reduce the sulfur content and nitrogen content as much as possible.

  The polyolefin includes polymers of various olefins or hydrides thereof. Any olefin may be used, and examples thereof include ethylene, propylene, butene (1-butene, 2-butene, isobutene), α-olefins having 5 or more carbon atoms, and the like. In the production of polyolefin, one of the above olefins may be used alone, or two or more may be used in combination.

  Any ester can be used as the ester. The alcohol constituting the ester may be either a monohydric alcohol or a polyhydric alcohol. The acid constituting the ester may be either a monobasic acid or a polybasic acid.

  As the monohydric alcohol, those having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms are usually used. Such alcohols may be linear or branched, and saturated. Or may be unsaturated. Specific examples of the alcohol having 1 to 24 carbon atoms include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol and pentadecanol. Hexadecanol, heptadecanol, octadecanol, nonadecanol, icosanol, heicosanol, tricosanol, tetracosanol, and mixtures thereof.

  As the polyhydric alcohol, those having 2 to 10 valences, preferably 2 to 6 valences are usually used. Specific examples of the 2 to 10 polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, polyethylene glycol (3 to 15 mer of ethylene glycol), propylene glycol, dipropylene glycol, and polypropylene glycol (3 to 15 of propylene glycol). Monomer), 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3 -Dihydric alcohols such as propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentylglycol; glycerin, polyglycerin (glycerin 2- Octamers such as diglycerin, triglyceride Phosphorus, tetraglycerin, etc.), trimethylolalkanes (trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) and their 2- to 8-mer, pentaerythritol and their 2- to 4-mer, 1,2,4- Butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol, etc. Polyhydric alcohols; sugars such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, and mixtures thereof That.

  Among these polyhydric alcohols, ethylene glycol, diethylene glycol, polyethylene glycol (ethylene glycol 3-10 mer), propylene glycol, dipropylene glycol, polypropylene glycol (propylene glycol 3-10 mer), 1,3- Propanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, glycerin, diglycerin, triglycerin, trimethylolalkane (trimethylolethane, trimethylolpropane, trimethylol Methylol butane and the like, and dimers and tetramers thereof, pentaerythritol, dipentaerythritol, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol , 1,2,3,4 butane tetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, divalent to hexavalent polyhydric alcohols and mixtures thereof, such as mannitol are preferred. Even more preferred are ethylene glycol, propylene glycol, neopentyl glycol, glycerin, trimethylol ethane, trimethylol propane, pentaerythritol, sorbitan, and mixtures thereof. Among these, neopentyl glycol, trimethylol ethane, trimethylol propane, pentaerythritol, and a mixture thereof are preferable because higher oxidation stability is obtained, and most preferably pentaerythritol, dipentaerythritol, and a mixture thereof. It is.

  Of the acids constituting the ester according to the present invention, the monobasic acid usually includes a fatty acid having 2 to 24 carbon atoms or an aromatic monobasic acid.

  The fatty acid may be linear or branched, and may be saturated or unsaturated. Specifically, for example, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid , Saturated fatty acids such as heptadecanoic acid, octadecanoic acid, hydroxyoctadecanoic acid, nonadecanoic acid, icosanoic acid, heicosanoic acid, docosanoic acid, tricosanoic acid, tetracosanoic acid, acrylic acid, butenoic acid, pentenoic acid, hexenoic acid, heptenoic acid, octenoic acid , Nonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, octadecenoic acid, hydroxyoctadecenoic acid, nonadecenoic acid, icosenoic acid, henicosenoic acid, docosenoic acid, tricosenoic acid , Unsaturated fatty acids such as Torakosen acid, and mixtures thereof.

  Moreover, benzoic acid etc. are mentioned as an aromatic monobasic acid.

  Examples of the polybasic acid include aliphatic dibasic acids having 2 to 16 carbon atoms and aromatic polybasic acids.

  The dibasic acid having 2 to 16 carbon atoms may be linear or branched, and may be saturated or unsaturated. Specifically, for example, ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, nonanedioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, Tridecanedioic acid, tetradecanedioic acid, heptadecanedioic acid, hexadecanedioic acid, hexenedioic acid, heptenedioic acid, octenedioic acid, nonenedioic acid, decenedioic acid, undecenedioic acid, dodecenedioic acid, tridecenedioic acid, tetradecenedioic acid Examples include acids, heptadecenedioic acid, hexadecenedioic acid, and mixtures thereof.

  Examples of the aromatic polybasic acid include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid.

  The combination of the alcohol and the acid constituting the ester used in the present invention is arbitrary and is not particularly limited. In addition, each of the alcohol and acid may be used alone or as a mixture of two or more. Examples of esters that can be used in the present invention include esters of monohydric alcohols and monobasic acids, esters of polyhydric alcohols and monobasic acids, esters of monohydric alcohols and polybasic acids, and polyhydric alcohols and polybasic acids. Esters with basic acids, monohydric alcohols and polyhydric alcohols mixed with polybasic acids, polyhydric alcohols with monobasic acids and polybasic acid mixed acids, monohydric alcohols and polyhydric alcohols Examples include esters of mixed alcohols and mixed acids of monobasic acids and polybasic acids. The ester used in the present invention may be either a complete ester or a partial ester, but is preferably a complete ester.

  Among these, since it is excellent in abrasion resistance, an ester of a polyhydric alcohol and a monobasic acid, an ester of a monohydric alcohol and a polybasic acid is preferable, and an ester of a polyhydric alcohol and a monobasic acid is more preferable.

  As the polyhydric alcohol used for the ester of the polyhydric alcohol and the monobasic acid, any of the above can be used, but ethylene glycol, diethylene glycol, polyethylene glycol (ethylene glycol 3) is more excellent in abrasion resistance. -10mer), propylene glycol, dipropylene glycol, polypropylene glycol (3 to 10mer of propylene glycol), 1,3-propanediol, 2-methyl-1,2-propanediol, 2-methyl-1, 3-propanediol, neopentyl glycol, glycerin, diglycerin, triglycerin, trimethylolalkane (trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) and their dimers and tetramers, pentaerythritol, dipentaerythris Tol, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol glycerol condensate, Preferable are bivalent to hexavalent polyhydric alcohols such as adonitol, arabitol, xylitol, mannitol, and mixtures thereof. Even more preferred are ethylene glycol, propylene glycol, neopentyl glycol, glycerin, trimethylol ethane, trimethylol propane, pentaerythritol, sorbitan, and mixtures thereof. Among these, neopentyl glycol, trimethylol ethane, trimethylol propane, pentaerythritol, and a mixture thereof are preferable because higher oxidation stability is obtained, and most preferably pentaerythritol, dipentaerythritol, and a mixture thereof. It is.

  In addition, as the monobasic acid used for the ester of polyhydric alcohol and monobasic acid, any of the above can be used, but from the viewpoint of thermal stability, fatty acids having 2 to 24 carbon atoms are preferable, A fatty acid having 3 to 18 carbon atoms is more preferable, a fatty acid having 4 to 12 carbon atoms is further preferable, and a fatty acid having 5 to 9 carbon atoms is particularly preferable. In this case, the fatty acid can be used alone or in combination of two or more, but it is preferable to use a mixture of two or more fatty acids from the viewpoint of more excellent wear resistance. Further, the fatty acid may be either linear or branched, but it is preferable to use a linear fatty acid that can be obtained at a lower cost and is economically advantageous.

  The content of the base oil in the lubricating oil composition of the present invention is not particularly limited, but is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, particularly based on the total amount of the composition. Preferably it is 90 mass% or more.

The viscosity of the base oil is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 25 mm ² / s or less, more preferably 20 mm ² / s or less, still more preferably 15 mm ² / s or less, particularly preferably 10 mm ² / s. s or less. The kinematic viscosity at 100 ° C. is preferably 1.0 mm ² / s or more, more preferably 1.5 mm ² / s or more, still more preferably 2.0 mm ² / s or more, and particularly preferably 2.5 mm ² / s. That's it. The viscosity index of the base oil is not particularly limited, but is preferably 85 or more, more preferably 100 or more, and still more preferably 120 or more.

  Moreover, the lubricating oil composition of the present invention contains a phosphorus-containing carboxylic acid compound. The phosphorus-containing carboxylic acid compound is not particularly limited as long as it contains both a carboxyl group and a phosphorus atom in the same molecule. However, phosphorylated carboxylic acids are preferred from the viewpoint of extreme pressure and thermal / oxidative stability.

  Examples of the phosphorylated carboxylic acid include a compound represented by the following general formula (1).

［式（１）中、Ｒ^１及びＲ^２は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜３０の炭化水素基を示し、Ｒ^３は炭素数１〜２０のアルキレン基を示し、Ｒ^４は水素原子又は炭素数１〜３０の炭化水素基を示し、炭素数Ｘ^１、Ｘ^２、Ｘ^３及びＸ^４は同一でも異なっていてもよく、それぞれ酸素原子又は硫黄原子を示す。］
一般式（１）中、Ｒ^１及びＲ^２はそれぞれ水素原子又は炭素数１〜３０の炭化水素基を表す。炭素数１〜３０の炭化水素基としては、アルキル基、アルケニル基、シクロアルキル基、ビシクロアルキル基、トリシクロアルキル基、アルキルシクロアルキル基、アルキルビシクロアルキル基、アルキルトリシクロアルキル基、シクロアルキルアルキル基、ビシクロアルキルアルキル基、トリシクロアルキルアルキル基、アリール基、アルキルアリール基、アリールアルキル基等が挙げられる。また、Ｒ^１とＲ^２が結合して下記一般式（２）で表される２価の基を形成してもよい。なお、当該２価の基の２個の結合手はそれぞれＸ^１、Ｘ^２と結合するものである。

[In Formula (1), R ¹ and R ² may be the same or different, and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and R ³ represents an alkylene group having 1 to 20 carbon atoms. , R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and the carbon numbers X ¹ , X ² , X ³ and X ⁴ may be the same or different and each represents an oxygen atom or a sulfur atom. ]
In General Formula (1), R ¹ and R ² each represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group, an alkenyl group, a cycloalkyl group, a bicycloalkyl group, a tricycloalkyl group, an alkylcycloalkyl group, an alkylbicycloalkyl group, an alkyltricycloalkyl group, and a cycloalkylalkyl. Group, bicycloalkylalkyl group, tricycloalkylalkyl group, aryl group, alkylaryl group, arylalkyl group and the like. R ¹ and R ² may be bonded to form a divalent group represented by the following general formula (2). The two bonds of the divalent group are bonded to X ¹ and X ² , respectively.

［式（２）中、Ｒ^５及びＲ^６は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜４のアルキル基を示し、Ｒ^５及びＲ^６の双方がメチル基であることが好ましい。］
Ｒ^１及びＲ^２としては、これらの中でもアルキル基、シクロアルキル基、シクロアルキルアルキル基、トリシクロアルキルアルキル基、アリール基、アルキルアリール基、Ｒ^１とＲ^２とが結合した上記一般式（２）で表されるような２価の基であることが好ましく、アルキル基であることがより好ましい。

[In the formula (2), R ⁵ and R ⁶ may be the same or different, each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and both R ⁵ and R ⁶ are methyl groups. preferable. ]
R ¹ and R ² include, among these, an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, a tricycloalkylalkyl group, an aryl group, an alkylaryl group, and the above general formula (2) in which R ¹ and R ² are bonded. ) Is preferably a divalent group, and more preferably an alkyl group.

The alkyl group as R ¹ and R ² may be linear or branched. The alkyl group preferably has 1 to 18 carbon atoms. Specific examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, 3-heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, 2-ethylbutyl group, 1- Methylphenyl group, 1,3-dimethylbutyl group, 1,1,3,3-tetramethylbutyl group, 1-methylhexyl group, isoheptyl group, 1-methylheptyl group, 1,1,3-trimethylhexyl group and Examples include 1-methylundecyl group. Among these, a C3-C18 alkyl group is preferable and a C3-C8 alkyl group is more preferable.

Examples of the cycloalkyl group as R ¹ and R ² include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and a cyclododecyl group. Among these, a cycloalkyl group having 5 or 6 carbon atoms (cyclopentyl group and cyclohexyl group) is preferable, and a cyclohexyl group is particularly preferable.

The cycloalkylalkyl group as R ¹ and R ² is preferably a cycloalkylmethyl group, more preferably a cycloalkylmethyl group having 6 or 7 carbon atoms, and particularly preferably a cyclopentylmethyl group and a cyclohexylmethyl group.

As the bicycloalkylalkyl group as R ¹ and R ² , a bicycloalkylmethyl group is preferable, a bicycloalkylmethyl group having 9 to 11 carbon atoms is more preferable, and a decalinylmethyl group is particularly preferable.

The tricycloalkylalkyl group as R ¹ and R ² is preferably a tricycloalkylmethyl group, more preferably a tricycloalkylmethyl group having 9 to 15 carbon atoms, represented by the following formula (3) or (4). Particularly preferred are the groups

Ｒ^１、Ｒ^２としてのアリール基及びアルキルアリール基としては、フェニル基、トリル基、キシリル基、エチルフェニル基、ビニルフェニル基、メチルフェニル基、ジメチルフェニル基、トリメチルフェニル基、エチルフェニル基、イソプロピルフェニル基、第三ブチルフェニル基、ジ−第三ブチルフェニル基、２，６−ジ−tert−ブチル−４−メチルフェニル基等が挙げられる。これらの中でも、炭素数６〜１５のアリール基及びアルキルアリール基が好ましい。

As the aryl group and alkylaryl group as R ¹ and R ² , phenyl group, tolyl group, xylyl group, ethylphenyl group, vinylphenyl group, methylphenyl group, dimethylphenyl group, trimethylphenyl group, ethylphenyl group, isopropyl Examples thereof include a phenyl group, a tert-butylphenyl group, a di-tert-butylphenyl group, and a 2,6-di-tert-butyl-4-methylphenyl group. Among these, an aryl group having 6 to 15 carbon atoms and an alkylaryl group are preferable.

R ³ represents an alkylene group having 1 to 20 carbon atoms. The number of carbon atoms of the alkylene group is preferably 1 to 10, more preferably 2 to 6, and further preferably 3 to 4. Moreover, as such an alkylene group, what is represented by following General formula (5) is preferable.

一般式（５）中、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜４の炭化水素基を示し、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０の炭素数の合計は６以下である。また、好ましくは、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜３の炭化水素基を示し、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０の炭素数の合計は５以下である。さらに好ましくは、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１又は２の炭化水素基を示し、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０の炭素数の合計は４以下である。特に好ましくは、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜２の炭化水素基を示し、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０の炭素数の合計は３以下である。最も好ましくは、Ｒ^９又はＲ^１０のいずれかがメチル基であり残りの３基が水素原子である。

In the general formula (5), R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and R ⁷ , R ⁸ , R The total number of carbon atoms of ⁹ and R ¹⁰ is 6 or less. Preferably, R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, and R ⁷ , R ⁸ , R ⁹ and The total number of carbon atoms of R ¹⁰ is 5 or less. More preferably, R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 or 2 carbon atoms, and R ⁷ , R ⁸ , R ⁹ and R 10 The total of ¹⁰ carbon atoms is 4 or less. Particularly preferably, R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 2 carbon atoms, and R ⁷ , R ⁸ , R ⁹ and R 10 The total of ¹⁰ carbon atoms is 3 or less. Most preferably, either R ⁹ or R ¹⁰ is a methyl group and the remaining three groups are hydrogen atoms.

In general formula (1) ^{R 4} in the show a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. Examples of the hydrocarbon group include the hydrocarbon groups exemplified in the description of R ¹ and R ² .

Further, X ¹ , X ² , X ³ and X ⁴ in the general formula (1) may be the same or different and each represents an oxygen atom or a sulfur atom. From the point of extreme pressure, one or more of X ¹ , X ² , X ³ or X ⁴ are preferably sulfur atoms, more preferably two or more are sulfur atoms, and two are sulfur atoms. More preferably, the remaining two are oxygen atoms. In this case, it is arbitrary which of X ¹ , X ² , X ³ or X ⁴ is a sulfur atom, but X ¹ and X ² are oxygen atoms, and X ³ and X ⁴ are sulfur atoms. It is preferable.

  As mentioned above, although each group in General formula (1) was demonstrated, since it is excellent in extreme pressure property, (beta) -dithio phosphorylated propionic acid represented by following General formula (6) is used preferably.

［式（６）中、Ｒ^１、Ｒ^２はそれぞれ式（１）中のＲ^１、Ｒ^２と同一の定義内容を示し、Ｒ^７、Ｒ^８、Ｒ^９、Ｒ^１０はそれぞれ（５）中のＲ^７、Ｒ^８、Ｒ^９、Ｒ^１０と同一の定義内容を示す。］
本発明の潤滑油組成物におけるリン含有カルボン酸化合物の含有量は特に制限されないが、組成物全量基準で、好ましくは０．００１〜１質量％、より好ましくは０．００２〜０．５質量％である。リン含有カルボン酸化合物の含有量が前記下限値未満では十分な潤滑性が得られない傾向にある。一方、前記上限値を超えても含有量に見合う潤滑性向上効果が得られない傾向にあり、更には熱・酸化安定性や加水分解安定性が低下するおそれがあるので好ましくない。なお、一般式（１）で表されるホスホリル化カルボン酸のうち、Ｒ^４が水素原子である化合物（一般式（６）で表されるβ−ジチオホスホリル化プロピオン酸を含む）の含有量については、好ましくは０．００１〜０．１質量％、より好ましくは０．００２〜０．０８質量％、更に好ましくは０．００３〜０．０７質量％、一層好ましくは０．００４〜０．０６質量％、特に好ましくは０．００５〜０．０５質量％である。当該含有量が０．００１未満の場合は極圧性向上効果が不十分となるおそれがあり、一方、０．１質量％を超えると熱・酸化安定性が低下するおそれがある。

Wherein ^(6), R 1, ^{R 2} represents a ^R 1, ^{R 2} identical definitions and their respective formulas ^{(1), R 7, R 8, R} 9, R 10 are each (5) The same definition content as R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ is shown. ]
The content of the phosphorus-containing carboxylic acid compound in the lubricating oil composition of the present invention is not particularly limited, but is preferably 0.001 to 1% by mass, more preferably 0.002 to 0.5% by mass, based on the total amount of the composition. It is. If the content of the phosphorus-containing carboxylic acid compound is less than the lower limit, sufficient lubricity tends to be not obtained. On the other hand, even if the upper limit is exceeded, there is a tendency that an effect of improving lubricity commensurate with the content tends not to be obtained, and furthermore, heat / oxidation stability and hydrolysis stability may be lowered. Regarding the phosphorylated carboxylic acid represented by the general formula (1), the content of the compound in which R ⁴ is a hydrogen atom (including β-dithiophosphorylated propionic acid represented by the general formula (6)). Is preferably 0.001 to 0.1% by mass, more preferably 0.002 to 0.08% by mass, still more preferably 0.003 to 0.07% by mass, and still more preferably 0.004 to 0.06%. % By mass, particularly preferably 0.005 to 0.05% by mass. If the content is less than 0.001, the effect of improving extreme pressure may be insufficient. On the other hand, if the content exceeds 0.1% by mass, the heat / oxidation stability may be lowered.

  The lubricating oil composition of the present invention contains a phosphorus compound. Phosphorus compounds include phosphoric acid ester, acidic phosphoric acid ester, amine salt of acidic phosphoric acid ester, chlorinated phosphoric acid ester, phosphorous acid ester, phosphorothionate, zinc dithiophosphate, dithiophosphoric acid and alkanol or polyether type An ester with an alcohol or a derivative thereof is preferably used from the viewpoint of thermal and oxidation stability.

  Specific examples of phosphate esters include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate, tritridecyl Phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, and And xylenyl diphenyl phosphate.

  Specific examples of the acidic phosphate ester include monobutyl acid phosphate, monopentyl acid phosphate, monohexyl acid phosphate, monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acid phosphate, monodecyl acid phosphate, monoundecyl acid phosphate , Monododecyl acid phosphate, monotridecyl acid phosphate, monotetradecyl acid phosphate, monopentadecyl acid phosphate, monohexadecyl acid phosphate, monoheptadecyl acid phosphate, monooctadecyl acid phosphate, monooleyl acid phosphate, dibutyl acid phosphate Dipentyl acid phosphate, dihexyl Ruacid phosphate, diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecyl acid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl acid phosphate, dipentadecyl phosphate, dipentadecyl phosphate Examples include dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, and dioleyl acid phosphate.

  Examples of the amine salt of acidic phosphate ester include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, Examples include salts with amines such as dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, and trioctylamine.

  Examples of the chlorinated phosphate ester include tris-dichloropropyl phosphate, tris-chloroethyl phosphate, tris-chlorophenyl phosphate, and polyoxyalkylene bis [di (chloroalkyl)] phosphate.

  As phosphites, dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, dioleyl Phosphite, diphenyl phosphite, dicresyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl phosphite Phyto, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, tricresyl phosphite and the like can be mentioned.

  Specific examples of the phosphorothioate include tributyl phosphorothioate, tripentyl phosphorothioate, trihexyl phosphorothionate, triheptyl phosphorothionate, trioctyl phosphorothionate, trinonyl. Phosphorothioate, tridecyl phosphorothionate, triundecyl phosphorothionate, tridodecyl phosphorothionate, tritridecyl phosphorothionate, tritetradecyl phosphorothionate, tripentadecyl phosphorothionate, Trihexadecyl phosphorothioate, triheptadecyl phosphorothionate, trioctadecyl phosphorothionate, trioleyl phosphorothionate, triphenyl phosphorothionate, tricresyl phosphorothio Onate, trixylenyl phosphorothioate, cresyl diphenyl phosphorothioate, xylenyl diphenyl phosphorothioate, tris (n-propylphenyl) phosphorothionate, tris (isopropylphenyl) phosphorothionate, tris (N-butylphenyl) phosphorothionate, tris (isobutylphenyl) phosphorothionate, tris (s-butylphenyl) phosphorothionate, tris (t-butylphenyl) phosphorothionate, and the like. Mixtures of these can also be used.

  Among the above-mentioned phosphorus compounds, phosphoric acid ester, acidic phosphoric acid ester, amine salt of acidic phosphoric acid ester, chlorinated phosphoric acid ester, phosphorous acid ester and phosphorothioate are superior in various performances such as extreme pressure. Nate is preferred, phosphate esters are more preferred, and triaryl phosphates such as triphenyl phosphate, tricresyl phosphate, monocresyl diphenyl phosphate, dicresyl monophenyl phosphate are even more preferred.

  The content of the phosphorus compound in the lubricating oil composition of the present invention is not particularly limited, but is preferably 0.01 to 5.0% by mass, more preferably 0.05 to 4.5% by mass, based on the total amount of the composition. More preferably, it is 0.1-4.0 mass%, More preferably, it is 0.5-3.5 mass%, Most preferably, it is 1.0-3.0 mass%. If the content of the phosphorus compound is less than 0.01, the effect of improving the extreme pressure due to the inclusion of the phosphorus compound may be insufficient. On the other hand, if the content exceeds 5.0% by mass, the heat / oxidation stability and foaming properties are increased. May decrease.

  The lubricating oil composition of the present invention contains at least one selected from alkylphenols and aromatic amines.

  As an alkylphenol, the alkylphenol compound represented by the following general formula (7), (8) or (9) is mentioned as a preferable thing.

［式（７）中、Ｒ^１１は炭素数１〜４のアルキル基を示し、Ｒ^１２は水素原子又は炭素数１〜４のアルキル基を示し、Ｒ^１３は水素原子、炭素数１〜４のアルキル基、下記一般式（ｉ）又は（ｉｉ）：

Wherein ^{(7), R 11} represents an alkyl group having 1 to 4 carbon ^{atoms, R 12} represents a hydrogen atom or an alkyl group having 1 to 4 carbon ^{atoms, R 13} is a hydrogen atom, 1 to 4 carbon atoms An alkyl group, the following general formula (i) or (ii):

（一般式（ｉ）中、Ｒ^１４は炭素数１〜６のアルキレン基を示し、Ｒ^１５は炭素数１〜２４のアルキル基又はアルケニル基を示す。）

(In the general formula (i), R ¹⁴ represents an alkylene group having 1 to 6 carbon atoms, and R ¹⁵ represents an alkyl group or alkenyl group having 1 to 24 carbon atoms.)

（一般式（ｉｉ）中、Ｒ^１６は炭素数１〜６のアルキレン基を示し、Ｒ^１７は炭素数１〜４のアルキル基を示し、Ｒ^１８は水素原子又は炭素数１〜４のアルキル基を示し、ｋは０又は１を示す。）
で表される基を示す。］

(In the general formula (ii), R ¹⁶ represents an alkylene group having 1 to 6 carbon atoms, R ¹⁷ represents an alkyl group having 1 to 4 carbon atoms, and R ¹⁸ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. And k represents 0 or 1.)
The group represented by these is shown. ]

［一般式（８）中、Ｒ^１９及びＲ^２１は同一でも異なっていてもよく、それぞれ炭素数１〜４のアルキル基を示し、Ｒ^２０及びＲ^２２は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜４のアルキル基を示し、Ｒ^２３及びＲ^２４は同一でも異なっていてもよく、それぞれ炭素数１〜６のアルキレン基を示し、Ａは炭素数１〜１８のアルキレン基又は下記の一般式（ｉｉｉ）：
−Ｒ^２５−Ｓ−Ｒ^２６− （ｉｉｉ）
（一般式（ｉｉｉ）中、Ｒ^２５及びＲ^２６は同一でも異なっていてもよく、それぞれ炭素数１〜６のアルキレン基を示す）
で表される基を示す。］

[In General Formula (8), R ¹⁹ and R ²¹ may be the same or different and each represents an alkyl group having 1 to 4 carbon atoms; R ²⁰ and R ²² may be the same or different; Represents an atom or an alkyl group having 1 to 4 carbon atoms, R ²³ and R ²⁴ may be the same or different, each represents an alkylene group having 1 to 6 carbon atoms, and A represents an alkylene group having 1 to 18 carbon atoms or The following general formula (iii):
—R ²⁵ —S—R ²⁶ — (iii)
(In general formula (iii), R ²⁵ and R ²⁶ may be the same or different and each represents an alkylene group having 1 to 6 carbon atoms)
The group represented by these is shown. ]

一般式（９）中、Ｒ^２７は炭素数１〜４のアルキル基を示し、Ｒ^２８は水素原子又は炭素数１〜４のアルキル基を示し、Ｒ^２９は炭素数１〜６のアルキレン基又は下記一般式（ｉｖ）：

In General Formula (9), R ²⁷ represents an alkyl group having 1 to 4 carbon atoms, R ²⁸ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ²⁹ represents an alkylene group having 1 to 6 carbon atoms or The following general formula (iv):

（一般式（ｉｖ）中、Ｒ^３０及びＲ^３１は同一でも異なっていてもよく、それぞれ炭素数１〜６のアルキレン基を示す。）
で表される基を示す。］
上記一般式（７）で表される化合物において、Ｒ^１３が一般式（ｉ）で表される基である化合物の場合、一般式（ｉ）中のＲ^１４が炭素数１〜２のアルキレン基であり、Ｒ^１５が炭素数６〜１２の直鎖状又は分枝状アルキル基であるものがより好ましく、一般式（ｉ）のＲ^１４が炭素数１〜２のアルキレン基であり、Ｒ^１５が炭素数６〜１２の分枝状アルキル基であるものが特に好ましい。

(In general formula (iv), R ³⁰ and R ³¹ may be the same or different and each represents an alkylene group having 1 to 6 carbon atoms.)
The group represented by these is shown. ]
In the compound represented by the general formula (7), when R ¹³ is a group represented by the general formula (i), R ¹⁴ in the general formula (i) is an alkylene group having 1 to 2 carbon atoms. More preferably, R ¹⁵ is a linear or branched alkyl group having 6 to 12 carbon atoms, R ^{14 in the} general formula (i) is an alkylene group having 1 to 2 carbon atoms, and R ¹⁵ Is particularly preferably a branched alkyl group having 6 to 12 carbon atoms.

  Preferred compounds among the compounds represented by the general formula (7) are shown below.

Examples of the compound when R ¹³ is an alkyl group having 1 to 4 carbon atoms include 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-ethylphenol, etc. Can be mentioned.

Examples of compounds where R ¹³ is a group represented by the general formula (i) may include the following. N-hexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, isohexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-tert-butyl) -4-hydroxyphenyl) acetic acid n-heptyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isoheptyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-octyl Isooctyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, 2-ethylhexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-tert- Butyl-4-hydroxyphenyl) acetic acid n-nonyl, (3-methyl-5-tert-butyl-4 Hydroxyphenyl) isononyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-decyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isodecyl acetate, (3-methyl -5-tert-butyl-4-hydroxyphenyl) acetic acid n-undecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetoisodecyl, (3-methyl-5-tert-butyl-4-hydroxy) Phenyl) acetate n-dodecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isododecyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate n-hexyl, (3 -Methyl-5-tert-butyl-4-hydroxyphenyl) propionic acid Hexyl, n-heptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5 -Tert-butyl-4-hydroxyphenyl) n-octylpropionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isooctylpropionate, (3-methyl-5-tert-butyl-4-hydroxy) 2-ethylhexyl (phenyl) propionate, n-nonyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isononyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-butyl-4-hydroxyl N-decyl propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isodecyl propionate, n-undecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, Isoundecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, n-dodecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert -Butyl-4-hydroxyphenyl) isododecyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-hexyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid Isohexyl, (3,5-di-tert-butyl-4-hydroxyphenyl N-heptyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) isoheptyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-octyl, (3,5- Di-tert-butyl-4-hydroxyphenyl) isooctyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid 2-ethylhexyl, (3,5-di-tert-butyl-4-hydroxyphenyl) ) N-nonyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) isononyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-decyl, (3,5 -Di-tert-butyl-4-hydroxyphenyl) isodecyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) N-undecyl acid, (3,5-di-tert-butyl-4-hydroxyphenyl) isoundecyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-dodecyl, (3,5- Di-tert-butyl-4-hydroxyphenyl) isododecyl acetate, n-hexyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxy) (Phenyl) isohexylpropionate, (3,5-di-tert-butyl-4-hydroxyphenyl) n-heptylpropionate, (3,5-di-tert-butyl-4-hydroxyphenyl) isoheptylpropionate, (3 , 5-Di-tert-butyl-4-hydroxyphenyl) propionate n-octyl, (3,5-di- tert-butyl-4-hydroxyphenyl) isooctylpropionate, 2-ethylhexyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) ) N-nonyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) isononyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) n-decyl propionate, ( Isodecyl 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, n-undecyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert- Butyl-4-hydroxyphenyl) isoundecyl propionate, (3,5-di-tert Butyl-4-hydroxyphenyl) propionic acid n- dodecyl, and (3,5-di -tert- butyl-4-hydroxyphenyl) isododecyl propionate.

Examples of the compound when R ¹³ is a group represented by the general formula (ii) include bis (3,5-di-tert-butyl-4-hydroxyphenyl), bis (3,5-di-tert). -Butyl-4-hydroxyphenyl) methane, 1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) ethane, 1,2-bis (3,5-di-tert-butyl-4) -Hydroxyphenyl) ethane, 1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 1,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) Propane, 1,3-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane and the like; and A mixture of two or more of these may be used.

  Next, the alkylphenol represented by the general formula (8) will be described.

In General Formula (8), R ¹⁹ and R ²¹ may be the same or different and each represents an alkyl group having 1 to 4 carbon atoms. R ¹⁹ and R ²¹ are preferably a methyl group or a tert-butyl group, and more preferably both R ¹⁹ and R ²¹ are tert-butyl groups from the viewpoint of superior oxidation stability.

R ²⁰ and R ²² in general formula (8) may be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. As R ²⁰ and R ²² , a methyl group or a tert-butyl group is preferable, and both R ¹⁹ and R ²¹ are more preferably a tert-butyl group from the viewpoint of superior oxidation stability.

Moreover, R <^23> and R < ²⁴ > in General formula (8) may be same or different, and respectively show a C1-C6 alkylene group. Such an alkylene group may be linear or branched. Specific examples thereof include an alkylene group having 1 to 6 carbon atoms which is exemplified in the description of R ¹⁴ in the general formula (i).

In general formula (8), A shows a C1-C18 alkylene group or the bivalent group represented by the said general formula (iii). The alkylene group having 1 to 18 carbon atoms, other alkylene groups the described 1 to 6 carbon atoms exemplified by the R ¹⁴ in the general formula (i), heptylene group, octylene group, nonylene group, decylene group , Undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, pentadecylene group, octadecylene group and the like. Among these, from the viewpoint of availability of raw material, an alkylene group having 1 to 6 carbon atoms which is exemplified in the description of R ¹⁴ in the general formula (i) is preferably a straight-chain alkylene group having 2 to 6 carbon atoms Is particularly preferred.

Further, in the above general formula ^(iii), the alkylene group having 1 to 6 carbon atoms represented by ^{R 25} and ^{R 26,} carbon atoms exemplified in the description of ^{R 14} in the general formula (i) 1-6 Of the alkylene group. R ²⁵ and R ²⁶ are alkylene groups having 1 to 3 carbon atoms, for example, a methylene group, a methylmethylene group, an ethylene group, from the viewpoint of availability of raw materials when producing the compound represented by the general formula (8). (Diethylene group), ethylmethylene group, propylene group (methylethylene group), trimethylene group and the like are more preferable.

  A particularly preferable compound when A in the general formula (8) is an alkylene group having 1 to 18 carbon atoms is a compound represented by the following formula (8-1).

また、一般式（８）中のＡが式（ｉｉｉ）で表される基である場合の特に好ましい化合物は、下記式（８−２）で表される化合物である。

A particularly preferred compound when A in the general formula (8) is a group represented by the formula (iii) is a compound represented by the following formula (8-2).

次に、一般式（９）で表されるアルキルフェノールについて説明する。

Next, the alkylphenol represented by the general formula (9) will be described.

  Specifically preferable as the alkylphenol represented by the general formula (9) is a compound represented by the following formula (9-1) or (9-2).

上記アルキルフェノールは、１種を単独で用いてもよく、２種以上を組み合わせて用いてもよい。

The said alkylphenol may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of aromatic amines include phenyl-α-naphthylamine compounds and dialkyldiphenylamine compounds.

  As the phenyl-α-naphthylamine compound, phenyl-α-naphthylamine represented by the following general formula (10) is preferably used.

［式（１０）中、Ｒ^３２は水素原子又は炭素数１〜１６の直鎖状若しくは分枝状のアルキル基を示す。］
一般式（１０）中のＲ^３２がアルキル基である場合、当該アルキル基は前述の通り炭素数１〜１６の直鎖上又は分岐状のものである。このようなアルキル基としては、具体的には例えば、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシ基、トリデシル基、テトラデシル基、ペンタデシル基、及びヘキサデシル基等（これらのアルキル基は直鎖状でも分枝状でも良い）が挙げられる。なお、Ｒ^３２の炭素数が１６を超える場合には分子中に占める官能基の割合が小さくなり、酸化防止性能に悪影響を与える恐れがある。

[In the formula (10), R ³² represents a hydrogen atom or a linear or branched alkyl group having 1 to 16 carbon atoms. ]
When R ³² in the general formula (10) is an alkyl group, the alkyl group is linear or branched having 1 to 16 carbon atoms as described above. Specific examples of such an alkyl group include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, A tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, and the like (these alkyl groups may be linear or branched). The ratio of functional groups occupied in the molecule in the case where the number of carbon atoms of R ³² exceeds 16 decreases, which may adversely affect the anti-oxidation performance.

When R ³² in the general formula (10) is an alkyl group, from the viewpoint of excellent solubility, R ³² is preferably a branched alkyl group having 8 to 16 carbon atoms, and further an olefin oligomer having 3 or 4 carbon atoms. A branched alkyl group having 8 to 16 carbon atoms derived from is more preferable. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1-butene, 2-butene and isobutylene, and propylene or isobutylene is preferable from the viewpoint of solubility. In order to obtain better solubility, R ³² is derived from a branched octyl group derived from a dimer of isobutylene, a branched nonyl group derived from a trimer of propylene, or a trimer of isobutylene. Even more preferred are branched dodecyl groups, branched dodecyl groups derived from propylene tetramers or branched pentadecyl groups derived from propylene pentamers, and branched derived from isobutylene dimers. An octyl group, a branched dodecyl group derived from a trimer of isobutylene, or a branched dodecyl group derived from a tetramer of propylene is particularly preferred.

When R ³² is an alkyl group, it can be bonded to any position of the phenyl group, but is preferably in the p-position with respect to the amino group. Furthermore, the amino group can be bonded to any position of the naphthyl group, but is preferably in the α position.

  As phenyl-α-naphthylamine represented by the general formula (10), a commercially available product may be used, or a synthetic product may be used. The synthesized product is a reaction between phenyl-α-naphthylamine and a halogenated alkyl compound having 1 to 16 carbon atoms, or phenyl-α-naphthylamine and an olefin or carbon number having 2 to 16 carbon atoms, using a Friedel-Crafts catalyst. It can be easily synthesized by reacting with 2 to 16 olefin oligomers. Specific examples of Friedel-Crafts catalysts include metal halides such as aluminum chloride, zinc chloride, and iron chloride; acidic catalysts such as sulfuric acid, phosphoric acid, phosphorus pentoxide, boron fluoride, acidic clay, and activated clay. Etc. can be used.

  As the dialkyldiphenylamine compound, dialkyldiphenylamine represented by the following general formula (11) is preferably used.

［式（１１）中、Ｒ^３３及びＲ^３４は同一でも異なっていてもよく、それぞれ炭素数１〜１６のアルキル基を示す。］
Ｒ^３３及びＲ^３４で表されるアルキル基としては、具体的には、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシ基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基等（これらのアルキル基は直鎖状でも分枝状でも良い）が挙げられる。これらの中でも、溶解性に優れる点から、Ｒ^３３及びＲ^３４としては、炭素数３〜１６の分枝アルキル基が好ましく、炭素数３又は４のオレフィン又はそのオリゴマーから誘導される炭素数３〜１６の分枝アルキル基がより好ましい。炭素数３又は４のオレフィンとしては、具体的にはプロピレン、１−ブテン、２−ブテン及びイソブチレン等が挙げられるが、溶解性に優れる点から、プロピレン又はイソブチレンが好ましい。また、Ｒ^３３又はＲ^３４としては、更に優れた溶解性が得られることから、それぞれプロピレンから誘導されるイソプロピル基、イソブチレンから誘導されるｔｅｒｔ−ブチル基、プロピレンの２量体から誘導される分枝ヘキシル基、イソブチレンの２量体から誘導される分枝オクチル基、プロピレンの３量体から誘導される分枝ノニル基、イソブチレンの３量体から誘導される分枝ドデシル基、プロピレンの４量体から誘導される分枝ドデシル基又はプロピレンの５量体から誘導される分枝ペンタデシル基がさらにより好ましく、イソブチレンから誘導されるｔｅｒｔ−ブチル基、プロピレンの２量体から誘導される分枝ヘキシル基、イソブチレンの２量体から誘導される分枝オクチル基、プロピレンの３量体から誘導される分枝ノニル基、イソブチレンの３量体から誘導される分枝ドデシル基又はプロピレンの４量体から誘導される分枝ドデシル基が最も好ましい。

[In the formula (11), R ³³ and R ³⁴ may be the same or different and each represents an alkyl group having 1 to 16 carbon atoms. ]
Specific examples of the alkyl group represented by R ³³ and R ³⁴ include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and undecyl. Group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group and the like (these alkyl groups may be linear or branched). Among these, from the viewpoint of excellent solubility, as R ³³ and R ³⁴ , a branched alkyl group having 3 to 16 carbon atoms is preferable, and 3 to 3 carbon atoms derived from an olefin having 3 or 4 carbon atoms or an oligomer thereof. More preferred are 16 branched alkyl groups. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1-butene, 2-butene, and isobutylene, but propylene or isobutylene is preferable from the viewpoint of excellent solubility. Further, as R ³³ or R ³⁴ , since further excellent solubility can be obtained, isopropyl groups derived from propylene, tert-butyl groups derived from isobutylene, and components derived from dimers of propylene, respectively. Branched hexyl group, branched octyl group derived from isobutylene dimer, branched nonyl group derived from propylene trimer, branched dodecyl group derived from isobutylene trimer, propylene tetramer More preferred are branched dodecyl groups derived from the body or branched pentadecyl groups derived from the pentamer of propylene, tert-butyl groups derived from isobutylene, branched hexyl derived from the dimer of propylene Group, branched octyl group derived from isobutylene dimer, branched nonyl derived from propylene trimer , A branched dodecyl group derived from a tetramer of branched dodecyl or propylene derived from a trimer of isobutylene being most preferred.

When a compound in which one or both of R ^{33 and} R ³⁴ are hydrogen atoms is used, sludge may be generated due to oxidation of the compound itself. Moreover, when the number of carbon atoms of the alkyl group exceeds 16, the proportion of the functional group in the molecule becomes small, and the antioxidant property at high temperature may be lowered.

The alkyl group represented by R ³³ or R ³⁴ can be bonded to any position of the phenyl group, but is preferably p-position to the amino group, that is, represented by the general formula (11). The dialkyldiphenylamine is preferably p, p′-dialkyldiphenylamine.

  A commercially available dialkyldiphenylamine represented by the general formula (11) may be used, or a synthetic product may be used. The synthesized product uses a Friedel-Crafts catalyst, reaction of diphenylamine, a C1-C16 halogenated alkyl compound and diphenylamine, or diphenylamine and a C2-C16 olefin, a C2-C16 olefin, or these It can be easily synthesized by reacting with the above oligomer. As the Friedel-Crafts catalyst, metal halides and acidic catalysts exemplified in the description of the phenyl-α-naphthylamine-based compound are used.

  The aromatic amines represented by the general formulas (10) and (11) may be used singly or as a mixture of two or more different structures. Therefore, it is preferable to use a phenyl-α-naphthylamine represented by the general formula (10) and a dialkyldiphenylamine represented by the general formula (11) in combination. The mixing ratio in this case is arbitrary, but is preferably in the range of 1/10 to 10/1 by mass ratio.

  In the lubricating oil composition of the present invention, one of the above alkylphenols or aromatic amines may be used alone, or both alkylphenols and aromatic amines may be used. It is preferable to use an amine.

  The total content of alkylphenol and aromatic amine in the lubricating oil composition of the present invention is not particularly limited, but is preferably 0.01 to 5.0% by mass, more preferably 0.00%, based on the total amount of the composition. It is 02-4.0 mass%, More preferably, it is 0.03-3.0 mass%, More preferably, it is 0.04-2.0 mass%, Most preferably, it is 0.05-1.0 mass%. When the total content is less than 0.01% by weight, the oxidation stability and thermal stability tend to be insufficient. On the other hand, when it exceeds 5.0 mass%, the effect of oxidation stability commensurate with the content cannot be obtained, and further, it causes an increase in sludge, which is not preferable.

  In the lubricating oil composition of the present invention, one kind of known lubricating oil additives can be used alone or in combination of two or more kinds for the purpose of further enhancing various performances. Examples of such additives include antioxidants such as zinc dithiophosphates and phenothiazines; rust inhibitors such as esters; defoamers such as acrylates such as polyacrylates and siloxanes such as alkylpolysiloxanes; Examples thereof include metal deactivators such as triazole or derivatives thereof; pour point depressants such as polymethacrylate, polyisobutylene, olefin copolymer, and polystyrene. The content in the case of using these additives is arbitrary, but based on the total amount of the composition, 0.01 to 0.1% by mass in the case of a rust inhibitor, 0.0005 to 1% in the case of an antifoaming agent %, In the case of a metal deactivator, 0.005 to 1% by mass, and in the case of many additives, 0.1 to 15% by mass is preferable.

The viscosity of the lubricating oil composition of the present invention is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 25 mm ² / s or less, more preferably 20 mm ² / s or less, still more preferably 15 mm ² / s or less, particularly preferably. Is 10 mm ² / s or less. The kinematic viscosity at 100 ° C. is preferably 1.0 mm ² / s or more, more preferably 1.5 mm ² / s or more, still more preferably 2.0 mm ² / s or more, and particularly preferably 2.5 mm ² / s. That's it. The viscosity index of the base oil is not particularly limited, but is preferably 85 or more, more preferably 100 or more, and still more preferably 120 or more.

  In addition, in the lubricating oil composition of the present invention, the sulfur content (element-converted value) in the composition is the total amount of the composition from the viewpoint of enhancing the heat and oxidation stability and particularly reducing the sludge generation amount sufficiently. On the basis, it is preferably 0.020% by mass or less, more preferably 0.015% by mass or less, and further preferably 0.010% by mass or less. The sulfur content here refers to a value measured by the “microcoulometric titration method” of JIS K 2541 “Crude oil and petroleum products—Sulfur content test method”.

  Although the use of the lubricating oil composition of the present invention is not particularly limited, it is particularly preferably used as a lubricating oil for a turbine apparatus equipped with a compressor and a speed increasing gear device. Turbine devices include hydraulic turbines, steam turbines, gas turbines, and the like. The lubricating oil composition of the present invention exhibits the most excellent effects particularly when used in a gas turbine device including a speed increasing gear device. There is no restriction | limiting in particular in the output number of such a gas turbine apparatus.

  Moreover, the lubricating oil composition of the present invention can be preferably used in applications such as hydraulic fluids, industrial gear oils, bearing oils, compressor oils, etc., in addition to the above applications, due to its excellent characteristics.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Example 1, Reference Examples 1 and 2, Comparative Examples 1 to 3]
In Example 1, Reference Examples 1 and 2, and Comparative Examples 1 to 3, lubricating oil compositions having the compositions shown in Table 1 were prepared using the base oils and additives shown below, respectively. Table 1 shows the kinematic viscosity, viscosity index, and sulfur content (sulfur element equivalent value) at 100 ° C. of each obtained lubricating oil composition.

(Base oil)
Base oil 1: paraffinic mineral oil (100 ° C.) obtained by applying a suitable combination of refining means such as hydrocracking and solvent dewaxing to a lubricating oil fraction obtained by upstream of crude oil at normal pressure Kinematic viscosity: 5.95 mm ² / s, viscosity index: 120, sulfur content (sulfur element equivalent): less than 10 mass ppm)
Base oil 2: Polyol ester obtained using pentaerythritol and a linear saturated fatty acid having 5 to 9 carbon atoms (kinematic viscosity at 100 ° C .: 4.94 mm ² / s, viscosity index: 130)
Base oil 3: 1-decene oligomer (kinematic viscosity at 100 ° C: 6.26 mm ² / s, viscosity index: 148)
(Additive)
A1: β-dithiophosphorylated propionic acid B1: tricresyl phosphate C1: phenyl-α-naphthylamine D1: dibenzyl sulfide.

  Next, the following tests were performed using the lubricating oil compositions of Example 1, Reference Examples 1 and 2, and Comparative Examples 1 to 3.

(Extreme pressure test)
The FZG test was conducted by the test method standardized by ASTM D 5182-91, and the extreme pressure property of the nuclear lubricating oil composition was evaluated. In the evaluation, the failed stage was used as an index. The obtained results are shown in Table 1.

(Thermal / oxidative stability test)
In the test specified in TOST of JIS K 2514, the amount of oil was 300 ml, heated to 120 ° C. in an oil bath without adding pure water, and oxygen was blown in at a flow rate of 3 l / h while maintaining the temperature. Copper and iron catalysts were used as catalysts. After 480 hours from the oxygen blowing start time, the lubricating oil composition was sufficiently stirred with an oxygen blowing tube, and 100 ml was collected. The collected oxidatively deteriorated oil was cooled to room temperature, filtered through a filter having a pore diameter of 0.8 μm, and the insoluble matter on the filter was weighed. Furthermore, the oxidation life of the filtrate was measured by a method standardized by RBOT of the same JIS standard test. Furthermore, the RBOT value of the oxidatively deteriorated oil at each sampling time was divided by the RBOT value of the new oil measured in advance to obtain the RBOT residual rate. The obtained results are shown in Table 1. In Table 1, it means that heat / oxidation stability is so favorable that the RBOT value of oxidation deterioration oil is large and the amount of insoluble matter with respect to the RBOT residual rate is small.

表１に示した結果から明らかなように、実施例１、参考例１、２の潤滑油組成物はいずれも十分に長い酸化寿命を示し、また、優れた耐スラッジ性及び極圧性を有していることが確認された。

As is clear from the results shown in Table 1, the lubricating oil compositions of Example 1 and Reference Examples 1 and 2 all have a sufficiently long oxidation life, and have excellent sludge resistance and extreme pressure resistance. It was confirmed that

Claims (4)

At least one base oil selected from esters of polyhydric alcohols and fatty acids having 5 to 9 carbon atoms, phosphorus-containing carboxylic acid compounds, phosphate esters, acidic phosphate esters, amine salts of acidic phosphate esters, chlorine A lubricating oil composition comprising: a phosphorus compound that is at least one selected from a phosphorylated phosphate and a phosphite; and at least one selected from an alkylphenol and an aromatic amine. The lubricating oil composition according to claim 1, wherein the polyhydric alcohol is pentaerythritol. The lubricating oil composition according to claim 1, wherein the phosphorus compound is a phosphate ester. The lubricating oil composition according to any one of claims 1 to 3, wherein the phosphorus-containing carboxylic acid compound is a compound represented by the following general formula (1).

[In Formula (1), R ¹ and R ² may be the same or different, and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and R ³ represents an alkylene group having 1 to 20 carbon atoms. , R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and the carbon numbers X ¹ , X ² , X ³ and X ⁴ may be the same or different and each represents an oxygen atom or a sulfur atom. ]