JP2008239895A - Lubricating oil composition containing phosphomolybdic compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of demanding an additive compensating for the ability of engine oil, which is deteriorated by the reduction in sulfur functioning as an antioxidizing agent in the context of looking for many openings, such as improvement in fuel saving performance and purification of and reduction in emission gases, by the automotive industry in order to address environmental problems such as global warming, including the reduction in sulfur content in lubricant base oil, where a base oil with much sulfur content sometimes causes emission of hazardous materials such as sulfur oxides into the environment. <P>SOLUTION: The lubricating oil composition according to the present invention comprises a novel phosphomolybdic compound and the base oil with a sulfur content of ≤200 ppm. Because a small amount of the novel phosphomolybdic compound shows ability equal to or better than that of an existing antioxidizing agent, the compound can improve a lubricant oil in the antioxidant ability without increasing the metal content in the lubricant oil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lubricating oil composition containing a phosphomolybdenum compound.

  In recent years, in order to cope with environmental problems such as global warming, which has become a very big problem, the automobile industry has been exploring a number of measures such as improving fuel efficiency and reducing purification of exhaust gas. One way to overcome this is to make engine oil a long drain. Since most engine oil is derived from fractions during refining of crude oil, the long-term use of this oil is an important issue that leads to the effective use of resources and the suppression of greenhouse gases generated during disposal. It can be said that there is.

  In general, engine oil is made by dissolving multiple additives such as antioxidants, friction modifiers, viscosity modifiers, detergents, dispersants, etc. in the base oil, and the characteristics of these additives and the base oil itself. Determines the performance of the engine oil. In order to realize a long drain, it is necessary to prevent oxidative degradation of engine oil over a long period of time, and the degree of purification of the base oil and the performance of the added antioxidant greatly affect the deterioration of the engine oil. Mineral oil, which is often used as a base oil, has been remarkably increased in refinement due to recent technological improvements, and its sulfur content, which was 1000 ppm or more in the past, is now reduced to one-fifth or less and widely used. It has become like this. As a result, it was possible to greatly reduce the elemental sulfur, which is one of the causes of poisoning of the exhaust gas purification catalyst, but the antioxidant performance of the base oil decreased due to the removal of the sulfur-containing compounds. . In addition, synthetic oils such as poly-α-olefins, which are considered to have better oxidation stability than mineral oils, may be mixed with mineral oils and used as engine oil base oils, but they are used because synthetic oils are expensive. A large increase in volume is difficult. Since the refinement degree of mineral oil is expected to continue to increase in order to protect the exhaust gas purifying catalyst, the performance of the added antioxidant is very important for the long drain of engine oil.

  Examples of the currently widely used antioxidant include oil-solubilized 2,6-ditertiary butylphenols (for example, see Patent Document 1) and alkylated diphenylamines (for example, see Patent Document 2). As can be seen from the fact that these compounds have been used for a long time, the performance is insufficient to realize a long drain. Increasing the amount used can slightly improve the effect, but using a certain amount or more may cause a large amount of sludge and deterioration of the rubber seal. Impossible. In addition, zinc dithiophosphates are used as antioxidants and antiwear agents, but the sulfur and phosphorus elements contained in these compounds are highly likely to poison the exhaust gas purification catalyst, and at the same time, engine oil standards May violate regulations on sulfur and phosphorous content, and a significant increase in usage is discouraged.

JP 2001-89782 A JP-A-10-298551

  Therefore, the problem to be solved by the present invention is to provide a lubricating oil additive that significantly improves the antioxidant performance in a base oil having a low sulfur concentration.

  As a result of intensive studies, the inventors have arrived at the present invention. That is, the present invention provides a mineral oil or PAO having a sulfur concentration of 200 ppm or less by reducing a hexavalent molybdenum compound with a reducing agent, neutralizing with a mineral acid, and reacting with a monoalkyl phosphate ester and / or dialkyl phosphate ester. A lubricating oil composition comprising the resulting phosphomolybdenum compound.

The effect of the present invention is to contribute to a long drain by adding a lubricating oil additive that significantly improves the antioxidant performance to mineral oil or PAO having a sulfur concentration of 200 ppm or less.

  The object of the present invention is to make the lubricating oil a long drain. Therefore, a high performance antioxidant is contained in the lubricating oil.

Examples of the hexavalent molybdenum compound that can be used in the present invention include molybdenum trioxide or a hydrate thereof (MoO ₃ .nH ₂ O), molybdic acid (H ₂ MoO ₄ ), sodium molybdate, potassium molybdate, and the like. Molybdate metal salt (M ₂ MoO ₄ ; M is a metal atom), ammonium molybdate [(NH ₄ ) ₂ MoO ₄ or (NH ₄ ) ₆ (Mo ₇ O ₂₄ ) 4H ₂ O], MoOCl ₄ , MoO ₂ Cl ₂ , MoO ₂ Br ₂ , Mo ₂ O ₃ Cl _{6, and the} like. Molybdenum trioxide or its hydrate, metal molybdate, ammonium molybdate and the like that are easily available are preferable.

  Examples of the reducing agent that can be used in the present invention include sulfoxylic acid, dithionic acid (hydrosulfite), sulfurous acid, hydrogen sulfite, pyrosulfurous acid, thiosulfuric acid, dithionic acid, sulfinic acid, and alkali metal salts thereof. Or alkaline-earth metal salt, thiourea dioxide, etc. are mentioned. Among these reducing agents, sulfinic acid, or an alkali metal salt or alkaline earth metal salt thereof, and thiourea dioxide are preferable because of high reaction rate.

  The mineral acid that can be used in the present invention may be any of monobasic acids, dibasic acids, tribasic acids or partially neutralized products thereof, but mineral acids containing phosphorus atoms such as phosphoric acid are used. Can not. Examples of the mineral acid that can be used include hydrochloric acid, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, perchloric acid, chloric acid, chlorous acid, hypochlorous acid, etc., but the product has high reaction efficiency and high purity. In view of the above, hydrochloric acid, nitric acid, and sulfuric acid are preferable, and a non-volatile one is preferable because it is easy to handle, and the use of sulfuric acid is particularly preferable.

The acidic phosphate ester that can be used in the present invention is a compound represented by the following general formula (1).

(R represents a hydrocarbon group, m and n represent a number of 1 or 2, and m + n = 3.)
Examples of R in the general formula (1) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tertiary butyl group, an amyl group, an isoamyl group, a hexyl group, a cyclohexyl group, a heptyl group, and an isoheptyl group. , Octyl group, isooctyl group, 2-ethylhexyl group, nonyl group, isononyl group, decyl group, dodecyl (lauryl) group, tridecyl group, tetradecyl (myristyl) group, pentadecyl group, hexadecyl (palmityl) group, peptadecyl group, octadecyl ( An alkyl group such as a stearyl group; vinyl group, 1-methylethenyl group, 2-methylethenyl group, propenyl group, butenyl group, isobutenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, decenyl group, pentadecenyl group, eicosenyl group Group, tricosenyl Alkenyl groups such as phenyl group, naphthyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-vinylphenyl group, 3-isopropylphenyl group, 4-isopropylphenyl group, 4-butyl Phenyl group, 4-isobutylphenyl group, 4-tert-butylphenyl group, 4-hexylphenyl group, 4-cyclohexylphenyl group, 4-octylphenyl group, 4- (2-ethylhexyl) phenyl group, 4-stearylphenyl group Aryl groups such as cyclohexyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, methylcyclopentyl group, methylcyclohexyl group, methylcycloheptyl group, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, methylcyclopentenyl group, methylcyclopentyl group Hexenyl group, a cycloalkyl group such as methylcyclopentadienyl heptenyl group.

  Among these hydrocarbon groups, stability when put in lubricating oil is good, and since sludge and the like are not generated, it is preferably an alkyl group and an aryl group, from the balance between solubility in oil and performance, An alkyl group having 6 to 12 carbon atoms and an aryl group are more preferable.

  When the value of m in the general formula (1) is 1, the general formula (1) becomes a monophosphate ester, and when the value of m is 2, it becomes a diphosphate ester. The phosphate ester that can be used in the present invention may be either a monophosphate ester or a diphosphate ester. However, since the reaction rate when reacted with a molybdenum compound is high, the acid phosphate ester used in the present invention is monophosphate. A mixture of an ester and a diphosphate is preferable. The ratio of the mixture is preferably monophosphate / diphosphate = 1/9 to 9/1, more preferably 3/7 to 7/3 in terms of mass ratio.

  The acidic phosphate ester that is a mixture of these can be obtained by reacting an alcohol represented by ROH with phosphoric acid, diphosphorus pentoxide, polyphosphoric acid, or the like. It is preferable to react with diphosphorus oxide. As a reaction method, for example, diphosphorus pentoxide may be gradually added to an alcohol represented by ROH at 20 to 80 ° C., and the whole amount may be added, followed by aging at 40 to 120 ° C. for 1 to 10 hours. The reaction ratio between the alcohol represented by ROH and diphosphorus pentoxide is 2 to 4 mol, preferably 2.5 to 3.5 mol, of alcohol with respect to 1 mol of diphosphorus pentoxide.

  Next, the manufacturing method of the novel phosphomolybdenum compound which is this invention is demonstrated. The hexavalent molybdenum compound used as a raw material is a solid and must be dissolved or dispersed in water in order to reduce with a reducing agent. Metal molybdate such as sodium molybdate and ammonium molybdate are water-soluble and can be dissolved in water as they are. However, when using molybdenum compounds that are insoluble in water such as molybdenum trioxide, an alkali agent is added. And then dissolved. Examples of the alkaline agent include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and basic nitrogen compounds such as ammonia, monoethanolamine, diethanolamine, and triethanolamine. Among these, sodium hydroxide, potassium hydroxide, and ammonia are preferable because they are easy to handle and inexpensive. The amount of water to be dissolved may be any amount as long as the hexavalent molybdenum compound is dissolved or dispersed, and preferably adjusted so that the solid content is 10 to 90% by mass. Moreover, the temperature at the time of making it melt | dissolve is 10-80 degreeC, Preferably it is 20-60 degreeC, More preferably, it is 20-40 degreeC.

  After the hexavalent molybdenum compound is made into an aqueous solution or aqueous dispersion, it must be reduced with a reducing agent. The addition amount of a reducing agent is 0.1-2 mol with respect to 1 mol of molybdenum in aqueous solution, Preferably it is 0.1-1 mol, More preferably, it is 0.2-0.8 mol. If the amount of the reducing agent is 0.1 mol or less, it cannot be reduced sufficiently. The temperature in the system when adding the reducing agent is preferably 40 to 90 ° C, more preferably 50 to 80 ° C, and stirring may be performed for 0.5 to 3 hours after the addition of the reducing agent.

  After reducing hexavalent molybdenum, it is neutralized with mineral acid. The addition amount of the mineral acid is 1 to 6 mol, preferably 2 to 5 mol, more preferably 3 to 5 mol if the acid is a monovalent acid with respect to 1 mol of molybdenum in the aqueous solution. Further, if it is a divalent acid, it may be a ½ mol amount of a monovalent acid, and if it is a trivalent acid, it may be a ３ mol amount of a monovalent acid. The divalent acid is 0.5 to 3 mol, preferably 1 to 2.5 mol, more preferably 1.5 to 2.5 mol. If the amount of mineral acid added is too small, the compound of the present invention will not be produced. If it is too large, an effect commensurate with the amount added will not appear, and further post-treatment of the mineral acid may be difficult. Moreover, it is preferable that the temperature in the system when adding a mineral acid is 30-90 degreeC, and 40-80 degreeC is more preferable. Furthermore, since addition of a mineral acid generates heat due to heat of neutralization, it is preferably added slowly over a period of 0.1 to 3 hours and more preferably over a period of 0.5 to 2 hours for safety. Further, after the addition, aging is preferably performed at 30 to 90 ° C. for 0.1 to 5 hours, and more preferably 0.5 to 3 hours.

  After neutralization with mineral acid, acid phosphate ester may be added as it is, but the reaction may proceed, but since the viscosity after reaction may increase or solid matter may precipitate, acid phosphate ester addition It is preferred to add the solvent before. As the solvent which can be used, any water-insoluble solvent may be used, for example, aromatic solvents such as benzene, toluene and xylene; aliphatic hydrocarbon solvents such as hexane and petroleum ether; dimethyl ether and diethyl ether and the like. Ether solvents; ketone solvents such as methyl ethyl ketone; In addition, a solvent that is difficult to remove such as mineral oil or synthetic oil may be used as long as it may remain after all the reactions are completed. Such a solvent is preferably added in an amount of 30 to 300 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the solid content in the system.

  Thereafter, the acidic phosphate ester represented by the general formula (1) is added to the system and reacted, and the addition amount of the acidic phosphate ester is 0.5-2. 5 mol, preferably 0.6-2 mol, more preferably 0.7-1.5 mol. If the addition amount of the acidic phosphate ester is too small, the compound of the present invention is not formed, and if it is too much, an unreacted acidic phosphate ester may remain. Moreover, it is preferable that the temperature in the system in the case of adding acidic phosphate ester is 30-90 degreeC, and 40-80 degreeC is more preferable. When adding acidic phosphate ester, adding slowly over 0.1 to 3 hours is preferable, and adding over 0.5 to 2 hours is more preferable. Further, after the addition, aging is preferably performed at 30 to 90 ° C., preferably 40 to 80 ° C. for 1 to 30 hours, and more preferably 3 to 20 hours.

  Although the phosphomolybdenum compound of the present invention is produced by reaction with an acidic phosphate, it is preferably purified to obtain a highly pure product. Any known method may be used as a purification method, for example, a method of removing solids produced as a by-product after removing water by distillation or the like, and distilling the phosphomolybdenum compound of the present invention after removing water. And a method of extracting the phosphomolybdenum compound of the present invention with an organic solvent. Among these purification methods, a purification method using an organic solvent is preferable because a purification step is easy and a high-purity product is obtained.

  As a specific method for purification using an organic solvent, for example, an organic solvent to be separated from water is placed in a reaction-finished system, stirred and allowed to stand to separate into two layers. The aqueous layer may be an upper layer or a lower layer. In any case, after removing the aqueous layer, the organic solvent in the obtained organic solvent layer is removed under reduced pressure, etc. A compound can be obtained. In order to reduce by-products and impurities, it is preferable to add water to the obtained organic solvent layer for washing.

  As the organic solvent that can be used, any organic solvent that can be separated from water may be used. For example, aromatic solvents such as benzene, toluene, xylene, hemimeritene, pseudocumene, mesitylene, cumene; pentane, hexane And aliphatic hydrocarbon solvents such as octane and petroleum ether; ether solvents such as dimethyl ether and diethyl ether; ketone solvents such as methyl ethyl ketone and methyl butyl ketone. Among these organic solvents, the use of an aromatic solvent is preferred, and the use of benzene, toluene, and xylene is more preferred because separation of the aqueous layer and the organic layer is easy. The amount of these organic solvents used is 20 to 400 parts by weight, preferably 50 to 200 parts by weight, based on 100 parts by weight of the solid content in the system. It is necessary to consider the amount.

  Here, JP-A-62-39696 discloses a phosphomolybdenum compound similar in production method to the phosphomolybdenum compound of the present invention. In the production method disclosed in JP-A-62-39696, a hexavalent molybdenum compound is reduced with a reducing agent, reacted with an acidic phosphorus compound, and then neutralized with mineral production. The difference between the reaction method of the present invention and the above reaction method is that the neutralization in mineral production is only before or after the reaction between the reduced molybdenum compound and the acidic phosphate ester. The antioxidant performance is different from that of the phosphomolybdenum compound of the present invention.

  The lubricating base oil that can be used in the lubricating oil composition of the present invention is not particularly limited as long as the sulfur concentration is 200 ppm or less, and is a general lubricating base oil conventionally used as a lubricating base oil, such as mineral oil, Synthetic oils and mixtures thereof are mentioned. More specifically, poly-α-olefin, ethylene-α-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, polyalkylene glycol, polyphenyl ether, alkyl-substituted diphenyl ether, polyol ester, dibasic acid ester, carbonate ester Synthetic oils such as silicone oil, fluorinated oil, GTL, paraffinic mineral oil, naphthenic mineral oil, or refined mineral oils obtained by purifying these can be used. These base oils may be used alone or in a mixture. Among these lubricating base oils, poly-α-olefin, ethylene-α-olefin copolymer, polybutene, alkylbenzene, alkylnaphthalene, paraffinic mineral oil, naphthenic mineral oil, GTL are preferred, and poly-α-olefin, paraffinic Mineral oil, naphthenic mineral oil, and GTL are more desirable. Further, it is preferable to use a base oil having a viscosity index of 100 or more, and more preferable to use poly-α-olefin, GTL, or refined mineral oil having a viscosity index of 100 or more.

A more preferable poly-α-olefin is a polymer having a number average molecular weight of 5000 to 1000000 derived from at least one selected from α-olefins having 8 to 20 carbon atoms, and a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s. belongs to. Further, as a more preferable ethylene-α-olefin copolymer, a structural unit derived from at least one selected from α-olefins having 8 to 20 carbon atoms is 50 to 99% by mass, and a structural unit derived from ethylene is 1 A polymer having a number average molecular weight of 5,000 to 1,000,000, contained in an amount of ˜50 mass%, and having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s.

Mineral oil is refined by hydrorefining, solvent removal, solvent extraction, solvent dewaxing, catalytic dewaxing, hydrocracking, sulfuric acid washing, clay treatment, etc., and kinematic viscosity at 100 ° C. is 1-20 mm ² / More preferred is s.

  In addition, although the antioxidant performance of synthetic oils such as poly-α-olefins is known to be high, the incorporation of a phosphomolybdenum compound that can be used in the present invention further improves the antioxidant performance.

The kinematic viscosity of the base oil is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably ² to 8 mm ² / s, more preferably 2.5 to ⁶ mm ² / s, and particularly preferably 3 to 4.5 mm. It is desirable to adjust to ² / s. When the kinematic viscosity at 100 ° C. of the lubricating base oil exceeds 8, the low-temperature viscosity characteristics may be deteriorated. When the kinematic viscosity is less than 2, the oil film formation at the lubrication site is insufficient, so that lubricity is achieved. Or the evaporation loss of the lubricating base oil may increase. The evaporation loss amount of the lubricating base oil is not particularly limited, but the NOACK evaporation amount is preferably adjusted to 10 to 50% by mass, more preferably 20 to 40% by mass, and particularly preferably 22 to 35% by mass. It is desirable that By using a lubricating base oil whose NOACK evaporation is adjusted to the above range, it is easy to achieve both low temperature characteristics and wear prevention. The NOACK evaporation amount here means an evaporation amount measured in accordance with CEC L-40-T-87.

As a specific example of the lubricating base oil in the present invention, for example, a base oil for transmission oil has a kinematic viscosity at 100 ° C. of 1.5 to 3.5 mm ² / s, preferably ² to 3.2 mm ² / s, More preferably, it is 2.5-3 mm < ² > / s, Sulfur content is 200 ppm or less, Preferably it is 100 ppm or less, More preferably, it is 50 ppm or less, NOACK evaporation is 20-80 mass%, Preferably it is 30-65 mass %, More preferably 30 to 55% by mass of base oil and a kinematic viscosity at 100 ° C. of 3.5 to 6 mm ² / s, preferably 3.8 to 4.5 mm ² / s, more preferably 3.9 to 4.3 mm ² / s, sulfur content of 200ppm or less, preferably 100ppm or less, more preferably 50 ppm, NOACK evaporation amount is 5-20 wt%, preferably 10 to 18% by mass, more preferably 12 to 16% by mass of base oil with a mass ratio of 10:90 to 90:10, preferably 25:75 to 75:25, more preferably 40:60 to 60:40 It is preferable that the kinematic viscosity, sulfur content, and NOACK evaporation amount of the mixed base oil at 100 ° C. are within the above ranges. As a result, it is possible to obtain a composition that can achieve both low-temperature characteristics and lubricating performance suitable as a transmission oil composition. The mixed base oil further has a kinematic viscosity at 100 ° C. of 6 mm ² / s or more, preferably 10 to 35 mm ² / s, and a sulfur content of 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less. A base oil having an evaporation amount of 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less may be mixed in a small amount, for example, 5 to 30% by mass.

  Further, as the engine oil, a mineral oil or synthetic oil having a viscosity index of 100 or more, preferably 110 or more can be used, but even if 1 to 100 parts by mass of synthetic oil is blended with 100 parts by mass of mineral oil. Good. The synthetic oil is preferably a poly-α-olefin or an ethylene-α-olefin copolymer, more preferably a poly-α-olefin.

  The lubricating oil composition of the present invention contains a base oil having a sulfur concentration of 200 ppm or less and a phosphomolybdenum compound. What is necessary is just to mix | blend so that it may become mass ppm, Preferably it is 20-100 mass ppm, More preferably, it is 30-80 mass ppm. If it is 10 ppm by mass or less, the effect as an antioxidant may not be exhibited, and if it exceeds 200 ppm by mass, an effect commensurate with the addition amount may not be obtained or sludge may be generated.

（式中、Ｒ^１及びＲ^２は炭化水素基を表わし、ａは０〜１／３の数を表わす。）
一般式（２）において、Ｒ^１及びＲ^２は炭化水素基を表わす。炭化水素基としては、例えば、アルキル基、アルケニル基、アリール基、シクロアルキル基、シクロアルケニル基等が挙げられる。 The lubricating oil composition of the present invention further includes a zinc dithiophosphate represented by the following general formula (2), thereby further improving the antioxidant performance.

(In the formula, R ¹ and R ² represent a hydrocarbon group, and a represents a number of 0 to 1/3.)
In the general formula (2), R ¹ and R ² represent a hydrocarbon group. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, and a cycloalkenyl group.

  Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, isopentyl, secondary pentyl, neopentyl, tertiary pentyl, hexyl, secondary hexyl, heptyl, 2 Secondary heptyl, octyl, 2-ethylhexyl, secondary octyl, nonyl, secondary nonyl, decyl, secondary decyl, undecyl, secondary undecyl, dodecyl, secondary dodecyl, tridecyl, isotridecyl, secondary tridecyl, tetradecyl, secondary tetradecyl , Hexadecyl, secondary hexadecyl, stearyl, eicosyl, docosyl, tetracosyl, triacontyl, 2-butyloctyl, 2-butyldecyl, 2-hexyloctyl, 2-hexyldecyl, 2-octyldecyl, 2-hexyldecyl 2-octyldodecyl, 2-decyltetradecyl, 2-dodecyl-hexadecyl, 2-hexadecyl octadecyl, 2-tetradecyl-octadecyl, monomethyl branched - include isostearyl.

  Examples of the alkenyl group include vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, oleyl and the like.

  Examples of the aryl group include phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, benzhydryl, trityl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, Nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, styrenated phenyl, p-cumylphenyl, phenylphenyl, benzylphenyl, α-naphthyl, β-naphthyl group and the like can be mentioned.

  Examples of the cycloalkyl group and cycloalkenyl group include a cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, methylcyclohexyl, methylcycloheptyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, methylcyclopentenyl, methylcyclohexenyl, methylcycloheptenyl group. Etc.

Among these hydrocarbon groups, R ¹ and R ² are preferably an alkyl group, and more preferably a secondary alkyl group. The number of carbon atoms is preferably 3 to 14, more preferably 3 to 10, and most preferably 3 to 8. R ¹ and R ² may be the same hydrocarbon group or different hydrocarbon groups.

In general formula (2), when a = 0, it is called neutral zinc dithiophosphate (neutral salt), and when a is 1/3, it is called basic zinc dithiophosphate (basic salt). It is.
Since zinc dithiophosphate is a mixture of these neutral and basic salts, a is represented by a number from 0 to 1/3. The number of a varies depending on the production method of zinc dithiophosphate, but is preferably 0.08 to 0.3, more preferably 0.15 to 0.3, and most preferably 0.18 to 0.3. When a is larger than 0.3, the hydrolysis stability may be deteriorated. When a is smaller than 0.08, the wear resistance of the blended lubricating oil may be deteriorated.

  The addition amount of zinc dithiophosphate needs to be determined in consideration of the addition amount of the phosphomolybdenum compound of the present invention. Zinc dithiophosphate is preferably added so that the total phosphorus content in the lubricating oil composition of the present invention is 800 ppm by mass or less, more preferably 600 ppm by mass or less, and 500 ppm by mass. It is more preferable to add so that it may become the following. When it exceeds 800 ppm by mass, sludge is generated, or when used for gasoline engine oil, the exhaust gas catalyst may be adversely affected. Moreover, when the total phosphorus content in the lubricating oil composition of the present invention is 100 ppm by mass or less, the antioxidant performance may be insufficient.

  The lubricating oil composition of the present invention further improves the antioxidant performance by containing a phenol-based antioxidant and / or an amine-based antioxidant. Examples of the phenolic antioxidant include 2,6-di-tert-butylphenol (hereinafter, tertiary butyl is abbreviated as t-butyl), 2,6-di-t-butyl-p-cresol, 2 , 6-Di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butylphenol, 4,4′-methylenebis (2, 6-di-t-butylphenol), 4,4'-bis (2,6-di-t-butylphenol), 4,4'-bis (2-methyl-6-t-butylphenol), 2,2'- Methylene bis (4-methyl-6-t-butylphenol), 2,2'-methylene bis (4-ethyl-6-t-butylphenol), 4,4'-butylidene bis (3-methyl-6-t-butylphenol) 4,4'-isopropylidenebis (2,6-di-t-butylphenol), 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,2'-methylenebis (4-methyl-6-) Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,6-bis (2'-hydroxy-3'-t-butyl-5'-methylbenzyl) -4-methylphenol 3-t-butyl-4-hydroxyanisole, 2-t-butyl-4-hydroxyanisole, octyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, 3- (4- Hydroxy-3,5-di-t-butylphenyl) stearyl propionate, oleyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate Dodecyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, decyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, 3- (4-hydroxy -3,5-di-t-butylphenyl) octyl propionate, tetrakis {3- (4-hydroxy-3,5-di-t-butylphenyl) propionyloxymethyl} methane, 3- (4-hydroxy-3 , 5-Di-t-butylphenyl) propionic acid glycerin monoester, ester of 3- (4-hydroxy-3,5-di-t-butylphenyl) propionic acid and glycerin monooleyl ether, 3- (4- Hydroxy-3,5-di-t-butylphenyl) propionic acid butylene glycol diester, 3- (4-hydroxy-3,5-di-t-butyl) Ruphenyl) propionic acid thiodiglycol diester, 4,4'-thiobis (3-methyl-6-t-butylphenol), 4,4'-thiobis (2-methyl-6-t-butylphenol), 2,2'- Thiobis (4-methyl-6-t-butylphenol), 2,6-di-t-butyl-α-dimethylamino-p-cresol, 2,6-di-t-butyl-4- (N, N'- Dimethylaminomethylphenol), bis (3,5-di-t-butyl-4-hydroxybenzyl) sulfide, tris {(3,5-di-t-butyl-4-hydroxyphenyl) propionyl-oxyethyl} isocyanurate, Tris (3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate, 1,3,5-tris (3,5-di-t-butyl-4-hydro Cibenzyl) isocyanurate, bis {2-methyl-4- (3-n-alkylthiopropionyloxy) -5-t-butylphenyl} sulfide, 1,3,5-tris (4-t-butyl-3-hydroxy-) 2,6-dimethylbenzyl) isocyanurate, tetraphthaloyl-di (2,6-dimethyl-4-tert-butyl-3-hydroxybenzylsulfide), 6- (4-hydroxy-3,5-di-t-) Butylanilino) -2,4-bis (octylthio) -1,3,5-triazine, 2,2-thio- {diethyl-bis-3- (3,5-di-t-butyl-4-hydroxyphenyl)} Propionate, N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamide), 3,5-di-t-butyl-4-hydroxy- Benzyl-phosphoric acid diester, bis (3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, 3,9-bis [1,1-dimethyl-2- {β- (3-t-butyl-4 -Hydroxy-5-methylphenyl) propionyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4-hydroxy-5- t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, bis {3,3'-bis- ( 4′-hydroxy-3′-t-butylphenyl) butyric acid} glycol ester and the like.

  The content of the phenolic antioxidant is preferably 0.01 to 5% by mass, more preferably 0.05 to 4% by mass, and further preferably 0.1 to 3% by mass with respect to the total amount of the lubricating oil composition of the present invention. preferable. If the amount is 0.01% by mass or less, the effect of the phenolic antioxidant may not appear. If the amount exceeds 5% by mass, the effect corresponding to the amount added may not be obtained or sludge may be generated.

  Examples of amine-based antioxidants include 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine, and phenyl-2. -Naphthylamine antioxidants such as naphthylamine; N, N'-diisopropyl-p-phenylenediamine, N, N'-diisobutyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N, N ' -Di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N '-Phenyl-p-phenylenediamine, dioctyl-p Phenylenediamine antioxidants such as phenylenediamine, phenylhexyl-p-phenylenediamine, phenyloctyl-p-phenylenediamine; dipyridylamine, diphenylamine, p, p'-di-n-butyldiphenylamine, p, p'-di -T-butyldiphenylamine, p, p'-di-t-pentyldiphenylamine, p, p'-dioctyldiphenylamine, p, p'-dinonyldiphenylamine, p, p'-didecyldiphenylamine, p, p'-di Diphenylamines such as dodecyldiphenylamine, p, p'-distyryldiphenylamine, p, p'-dimethoxydiphenylamine, 4,4'-bis (4-α, α-dimethylbenzoyl) diphenylamine, p-isopropoxydiphenylamine, dipyridylamine Antioxidant; phenothiazine, N- methyl phenothiazine, N- ethylphenothiazine, 3,7-dioctylphenothiazine, phenothiazine carboxylate ester, phenothiazine-based antioxidants such as phenol Serena gin and the like.

  The content of the amine-based antioxidant is preferably 0.01 to 5% by mass, more preferably 0.05 to 4% by mass, and still more preferably 0.1 to 3% by mass with respect to the total amount of the lubricating oil composition of the present invention. preferable. If the amount is 0.01% by mass or less, the effect of the amine-based antioxidant may not appear. If the amount exceeds 5% by mass, the effect corresponding to the amount added may not be obtained or sludge may be generated.

  Furthermore, the lubricating oil composition of the present invention does not refuse the addition of known lubricating oil additives, and depending on the intended use, friction reducers, extreme pressure agents, oiliness improvers, detergents, dispersants, viscosity An index improver, a pour point depressant, a rust inhibitor, a corrosion inhibitor, an antifoaming agent, and the like may be added as long as the effects of the present invention are not impaired. However, when using a phosphorus-based additive among these, the total phosphorus content in the engine oil increases, so it is necessary not to exceed the range defined in the present invention.

  Examples of the friction reducing agent include organic molybdenum compounds such as sulfurized oxymolybdenum dithiocarbamate and sulfurized oxymolybdenum dithiophosphate. A preferable blending amount of these friction reducing agents is 30 to 2000 ppm by mass, more preferably 50 to 1000 ppm by mass with respect to the base oil. However, the use of sulfurized oxymolybdenum dithiocarbamate is preferable to the sulfurized oxymolybdenum dithiophosphate containing a phosphorus atom, and the use of sulfurized oxymolybdenum dithiocarbamate having an alkyl group having 8 to 13 carbon atoms is more preferable.

  Examples of extreme pressure agents include sulfur-based additives such as sulfurized fats and oils, olefin polysulfides, and dibenzyl sulfide; phosphorus-based compounds such as monooctyl phosphate, tributyl phosphate, triphenyl phosphite, tributyl phosphite, and thiophosphate An organic metal compound such as a thiophosphate metal salt, a thiocarbamic acid metal salt, and an acidic phosphate metal salt; A preferable blending amount of these extreme pressure agents is 0.01 to 2% by mass, more preferably 0.05 to 1% by mass with respect to the base oil. However, it is preferable to avoid the use of a compound containing a phosphorus atom as much as possible.

  Examples of oiliness improvers include higher alcohols such as oleyl alcohol and stearyl alcohol; fatty acids such as oleic acid and stearic acid; esters such as oleyl glycerin ester, steryl glycerin ester and lauryl glycerin ester; lauryl amide and oleyl Amides such as amide and stearylamide; amines such as laurylamine, oleylamine and stearylamine; ethers such as laurylglycerol ether and oleylglycerol ether. The preferable compounding quantity of these oiliness improvers is 0.1-5 mass% with respect to base oil, More preferably, it is 0.2-3 mass%.

  Examples of the detergent include sulfonates such as calcium, magnesium, and barium, phenates, salicylates, phosphates, and overbased salts thereof. Among these, overbased salts are preferable, and among the overbased salts, those having a TBN (total basic number) of 30 to 500 mgKOH / g are more preferable. Furthermore, salicylate-based detergents having no phosphorus and sulfur atoms are preferred. The preferable compounding quantity of these detergents is 0.5-10 mass% with respect to base oil, More preferably, it is 1-8 mass%.

  Examples of the dispersant include succinimide, succinate ester, benzylamine, and boron-modified products thereof to which an alkyl group or alkenyl group having a weight average molecular weight of about 500 to 3000 is added. The preferable compounding quantity of these dispersing agents is 0.5-10 mass% with respect to base oil, More preferably, it is 1-8 mass%.

  Examples of the viscosity index improver include poly (C1-18) alkyl methacrylate, (C1-18) alkyl acrylate / (C1-18) alkyl methacrylate copolymer, diethylaminoethyl methacrylate / (C1-18) alkyl methacrylate copolymer. Polymers, ethylene / (C1-18) alkyl methacrylate copolymers, polyisobutylene, polyalkylstyrene, ethylene / propylene copolymers, styrene / maleic ester copolymers, styrene / isoprene hydrogenated copolymers, and the like. . Alternatively, a dispersion type or multifunctional viscosity index improver imparted with a dispersion performance may be used. The average molecular weight is about 10,000 to 1,500,000. A preferable blending amount of these viscosity index improvers is 0.1 to 20% by mass with respect to the base oil. More preferably, it is 0.3-15 mass%.

  Examples of the pour point depressant include polyalkyl methacrylate, polyalkyl acrylate, polyalkyl styrene, polyvinyl acetate and the like, and the weight average molecular weight is 1000 to 100,000. A preferable blending amount of these pour point depressants is 0.005 to 3% by mass, more preferably 0.01 to 2% by mass with respect to the base oil.

  Examples of the rust preventive include sodium nitrite, oxidized paraffin wax calcium salt, oxidized paraffin wax magnesium salt, beef tallow fatty acid alkali metal salt, alkaline earth metal salt or amine salt, alkenyl succinic acid or alkenyl succinic acid half ester (alkenyl The molecular weight of the group is about 100 to 300), sorbitan monoester, nonylphenol ethoxylate, lanolin fatty acid calcium salt and the like. The preferable compounding quantity of these rust preventives is 0.01-3 mass% with respect to base oil, More preferably, it is 0.02-2 mass%.

  Examples of the corrosion inhibitor include benzotriazole, benzimidazole, benzothiazole, tetraalkylthiuram disulfide and the like. The preferable compounding quantity of these corrosion inhibitors is 0.01-3 mass% with respect to base oil, More preferably, it is 0.02-2 mass%.

  Examples of the antifoaming agent include polydimethyl silicone, trifluoropropylmethyl silicone, colloidal silica, polyalkyl acrylate, polyalkyl methacrylate, alcohol ethoxy / propoxylate, fatty acid ethoxy / propoxylate, sorbitan partial fatty acid ester and the like. The preferable compounding quantity of these antifoaming agents is 0.001-0.1 mass% with respect to base oil, More preferably, it is 0.001-0.01 mass%.

  The lubricating oil composition of the present invention simultaneously increases the antioxidant performance while suppressing the content of phosphorus atoms having various adverse effects. The phosphorus atom content may be changed depending on the intended use and usage environment, but is preferably 800 ppm by mass or less based on the total amount of the lubricating oil composition. However, in a diesel vehicle lubricating oil or the like not equipped with an exhaust gas catalyst or the like, there may be no problem even if the phosphorus content exceeds 800 mass ppm. Even in such a case, by adding the phosphomolybdenum compound of the present invention, the antioxidant performance of the lubricating oil is significantly improved as compared with the case where it is not added.

  The lubricating oil composition of the present invention can be used for any lubricating application, such as engine oil, gear oil, turbine oil, hydraulic oil, flame retardant hydraulic fluid, refrigerator oil, compressor oil, It can be used for lubricating oil such as vacuum pump oil, bearing oil, insulating oil, sliding surface oil, rock drill oil, metal working oil, plastic working oil, heat treatment oil, grease. Among these, it can be suitably used in engine oil and turbine oil in which the use environment is severe and antioxidation performance is required.

Hereinafter, the present invention will be specifically described by way of examples. In the following examples and the like,% and ppm are based on mass unless otherwise specified. The compounds used in the examples were synthesized by the following method.
Compound 1
In a 3000 ml flask equipped with a nitrogen introduction tube, a reflux tube, a stirrer, and a thermometer, 206 g of water was added to 1 mol (242 g) of sodium molybdate dihydrate and dissolved, and then the mixture was oxidized at 50 to 60 ° C. under a nitrogen stream. 0.5 mole (54 g) of thiourea was added and reacted for 1 hour. Subsequently, 2 mol of 20% sulfuric acid (980 g) was added dropwise over 1 hour and aged for 2 hours. After aging, the mixture was cooled to 30 to 40 ° C., 1 mol of dioleyl phosphate (598 g) was added dropwise over 1 hour, and the mixture was further reacted for 10 hours. To the obtained reaction product, 300 ml of n-hexane was added and stirred for 30 minutes, and then left for 1 hour to separate into two layers, an aqueous layer and an oil layer, and the aqueous layer was removed. Finally, the obtained oil layer was desolvated under reduced pressure to obtain 711 g of a dark brown oily product. As a result of analyzing the obtained dark brown oily product, the molybdenum content was 12.2% and the phosphorus content was 4.2%. The yield for molybdenum was 90%.
Compound 2
In the same manner as in Compound 1, instead of 1 mol of dioleyl phosphate, a mixture of 0.5 mol of monooctyl phosphate and 0.5 mol of dioctyl phosphate was added to 0.5 mol of hydrosal. Substituting 0.17 mol of hydrosulfite for the fight, 392 g of a dark blue oily product was obtained. The molybdenum content was 21.0% and the phosphorus content was 7.2%. The yield for molybdenum was 86%.
Compound 3
Zinc dithiophosphate (phosphorus content 8.2%, R ¹ = n-butyl, R ² = 1-octyl, a = 0.2 in the general formula (2))
Compound 4
p, p′-didodecyldiphenylamine (Example 1)
<Oxygen absorption test using a base oil with a sulfur content of less than 1 ppm>
Add 5 mg of the above compound 1 to each base oil to 5 g of base oil in a glass inner tube, stir to disperse and dissolve, then set in a 100 ml autoclave and attach pressure sensor and exhaust pipe Sealed with a lid. The air in the autoclave was discharged from the exhaust pipe using a vacuum pump, and oxygen was introduced instead, and the inside of the autoclave was brought into a 100% oxygen atmosphere, and at the same time, the pressure was set to 101 kPa. The autoclave was placed in a thermostat at 160 ° C. and the pressure was checked every 1 hour, and the time until the pressure fell below 80 kPa was measured as the oxidation induction period. As the oxidative degradation progresses, oxygen is consumed and the pressure decreases, so it can be determined that the longer the oxidation induction period, the better the antioxidant performance. In addition, it refine | purified previously so that the sulfur content of the used base oil might be less than 1 ppm, and all the kinematic viscosities in 100 degreeC are 2-4.5 mm < ² > / s. The results are shown in Table 1.
Table 1: Numbers in the table represent oxidation induction time, and the unit is time (hr).

If the oxidation induction period is 70 hours or longer, it can be used as a good lubricating oil, but compounds 1 and 2 showed an oxidation induction period of 70 hours or more in any base oil. On the other hand, all the existing antioxidants were less than 70 hours.
(Example 2)
<Oxygen absorption test using base oils with different sulfur contents>
The same test as in Example 1 was performed using mineral oils having different sulfur contents. Incidentally base oil used was a mineral oil-based high VI oil, 4.1 mm paraffinic mineral oil having a kinematic viscosity ^{2 /s(100℃),18.3mm 2 / s (40 ℃} ), viscosity index (VI) = 126, naphthenic mineral oil kinematic viscosity ^{4.0mm 2 /s(100℃),18.2mm 2 / s (40} ℃), a viscosity index (VI) = 118. The results are shown in Table 2.
Table 2: The numbers in the table represent oxidation induction time, and the unit is time (hr).

As mentioned above, if the oxidation induction period is 70 hours or more, it can be used as a good lubricating oil. Those having a sulfur content of 300 ppm show good results even with existing antioxidants. On the other hand, when the sulfur content is 150 ppm, the existing antioxidants have insufficient antioxidant performance, but those blended with the phosphomolybdenum compound that can be used in the present invention greatly exceed 70 hours and have good antioxidant performance. showed that.
(Example 3)
Using different types of base oils, engine oils with the following composition were blended and tested using actual car engines to see if they could be used as engine oils.
<Reference oil recipe>
Base oil 100 parts by weight Methacrylate viscosity index improver 3.5 parts by weight Succinimide dispersant 5.0 parts by weight Salicylate detergent 2.5 parts by weight Compound 1 0.5 parts by weight Compound 3 0.5 parts by weight <Base oil>
Base Oil 1: paraffinic mineral oil (kinematic viscosity ^{4.1mm 2 /s(100℃),18.3mm 2 / s (40} ℃), viscosity index (VI) = 126)
Base Oil 2: naphthenic mineral oil (kinematic viscosity ^{4.0mm 2 /s(100℃),18.2mm 2 / s (40} ℃), viscosity index (VI) = 118)
Base oil 3: poly-α-olefin (number average molecular weight 20000)
Base oil 4: Mixture of base oil 1 (70% by mass) and base oil 3 (30% by mass) As mentioned above, engine oils using four types of base oils could be used without problems in actual engines .

Claims (6)

A phosphomolybdenum compound obtained by reducing a hexavalent molybdenum compound to a base oil having a sulfur concentration of 200 ppm or less with a reducing agent, neutralizing with a mineral acid, and reacting with a monoalkyl phosphate ester and / or dialkyl phosphate ester A lubricating oil composition comprising: The lubricating oil composition according to claim 1, wherein the alkyl chain length of the monoalkyl phosphate ester and / or dialkyl phosphate ester is 4 to 18 carbon atoms. The lubricating oil composition according to claim 1 or 2, comprising zinc dithiophosphate and / or zinc phosphate. Furthermore, molybdenum dithiocarbamate and / or molybdenum dithiophosphate are contained, The lubricating oil composition of Claims 1-3 characterized by the above-mentioned. The lubricating oil composition according to claim 1, further comprising a phenol-based and / or amine-based antioxidant. Further, one kind selected from the group consisting of friction reducing agents, extreme pressure agents, oiliness improvers, detergents, dispersants, viscosity index improvers, pour point depressants, rust inhibitors, corrosion inhibitors and antifoaming agents. Or 2 or more types are contained, The lubricating oil composition in any one of Claims 1-5 characterized by the above-mentioned.