JPH11152486A - Lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricating oil composition having a low frictional coefficient and excellent in stability of the frictional coefficient even in long-time use in a temperature area of a wide range from a low-temperature area to high-temperature area. SOLUTION: This lubricating oil composition is obtained by compounding an effective amount of a lubricating oil base oil with (a) a sulfur-containing molybdenum-based compound, (b) an effective amount of at least one kind of an organic acid selected from the group comprising an aliphatic sulfonic acid, an aromatic sulfonic acid, an aromatic carboxylic acid and an aliphatic hydrocarbon group-substituted phenol compound and (c) an effective amount of zinc dithiophosphate. It is preferable that the compounding amount of the sulfur-containing organomolybdenum-based compound is 150-2,000 ppm as molybdenum amount and the compounding amount of the organic acid is 1-100 mmol/kg and the compounding amount of zinc dithiophosphate is 100-2,000 ppm as phosphorus amount, based on weight of the lubricating oil composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil composition, and more particularly, to a lubricating oil composition containing a sulfur-containing organic molybdenum compound, an organic acid, and zinc dithiophosphate and having an excellent friction reducing effect. It is about things. The lubricating oil composition of the present invention is useful in various fields such as lubricating oils for internal combustion engines, automatic transmission oils, gear oils, hydraulic oils, and plastic working oils.

[0002]

2. Description of the Related Art Reduction of friction and abrasion generated on sliding surfaces of moving parts of machinery, equipment, equipment, and the like is a fundamental problem of tribology, and many researches and developments have been made. In such research and development, the composition of the lubricating base oil has been improved to improve its quality, and various friction modifiers added to the lubricating base oil have been developed. For example, sulfided oxymolybdenum dithiophosphate ( Hereinafter, "MoDTP" is abbreviated, and oxymolybdenum dithiocarbamate sulfide (hereinafter, abbreviated as "MoDTC") has been proposed as a metal-based friction modifier (see, for example, JP-A-54-113604). ).

[0003] However, in recent years, the use conditions of lubricating oil have become severe with the improvement of the performance of internal combustion engines such as mechanical devices and automobiles. For example, for engine oil for automobiles, severe operating conditions resulting from stopping and starting operation have been observed. In addition to withstanding frequent repetitions of low-temperature conditions, it is required to be able to withstand high-temperature conditions resulting from long-time high-speed continuous operation. It is essential to reduce the friction loss of the internal combustion engine in order to improve the fuel consumption rate.
Friction modifiers such as C exhibit a reasonable friction-reducing effect at low temperatures, but lose their friction-reducing effects at high temperatures, and are sufficient for high-speed operation of machinery and vehicles that require operation under high-temperature conditions. It has been clarified from the result of the study of the present inventors that the possibility that a special effect cannot be obtained occurs. Therefore, the present inventors have proposed to improve the friction characteristics under high temperature conditions such as MoDTC by using MoDTC or the like and an organic acid in combination, but it is necessary to further improve the friction reduction effect under low temperature conditions. It turns out that there is.

[0004] Under such circumstances, there is a strong demand for a lubricating oil having an excellent friction reducing effect under a wide range of temperature conditions from a low temperature range to a high temperature range, and having excellent durability of the friction reducing effect over a long period of use. .

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve all the conditions that fluctuate in the use environment of a lubricating oil,
That is, an object of the present invention is to provide a lubricating oil composition capable of exhibiting an excellent friction reducing effect and its stability under a wide range of temperature conditions from a low temperature range to a high temperature range.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
In view of the state of development of conventional friction modifiers, as a result of diligent studies to solve the above problems, it is possible to solve the problems by using a sulfur-containing organic molybdenum compound in combination with a specific organic acid and zinc dithiophosphate. Have been found, and based on these findings, the present invention has been completed.

That is, the present invention relates to a lubricating base oil comprising a) a sulfur-containing organic molybdenum compound; b) an aliphatic sulfonic acid, an aromatic sulfonic acid, an aromatic carboxylic acid and an aliphatic hydrocarbon-substituted phenol compound. A lubricating oil composition comprising at least one organic acid selected from the group consisting of c) and zinc dithiophosphate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The lubricating base oil as a component of the lubricating oil composition of the present invention is appropriately selected depending on the use of the lubricating oil composition, but is not particularly limited as long as it exerts the effects of the present invention. Instead, those that are usually used as base oils for lubricating oils can be used. For example, mineral base oil, synthetic base oil, vegetable oil base oil and the like can be mentioned,
Each of these base oils can be used alone or in combination of two or more. Mineral base oils include solvent refining, hydrocracking, hydrotreating, and hydrogenation of lubricating oil fractions obtained as vacuum distillates of atmospheric distillation residual oils of paraffinic, intermediate base or naphthenic crude oils. Purification, catalytic dewaxing,
Solvent dewaxing, mineral oil obtained by arbitrarily selecting and using various purification steps such as clay treatment, and vacuum distillation residue oil are subjected to solvent deasphalting treatment, and then the deasphalted oil is subjected to the above-mentioned purification step. Mineral oil obtained by the treatment, mineral oil obtained by isomerization of the wax component, or a mixed oil thereof can be used. In the solvent purification, aromatic extraction solvents such as phenol, furfural and N-methyl-2-pyrrolidone are used, while liquefied propane, MEK / toluene and the like are used as solvents for solvent dewaxing. In the catalytic dewaxing, for example, a shape-selective zeolite or the like can be used as a dewaxing catalyst. In addition, from the viewpoint of oxidation stability and the like, a hydrotreated oil composed of a saturated hydrocarbon having an aromatic hydrocarbon content of 2% by weight or less obtained by the above hydrocracking and hydrotreating can be used.

On the other hand, synthetic base oils include poly-α-olefin oligomers (for example, poly (1-hexene), poly (1-octene), poly (1-decene) and mixtures thereof), polybutene, Alkylbenzenes (eg, dodecylbenzene, tetradecylbenzene, di (2
-Ethylhexyl) benzene, dinonylbenzene and the like. ), Polyphenyls (eg, biphenyl, alkylated polyphenyls, etc.), alkylated diphenyl ethers and alkylated diphenyl sulfides and derivatives thereof; dibasic acids (eg, phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, Maleic acid, azelaic acid, spearic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, etc.) and various alcohols (for example, butyl alcohol, hexyl alcohol, 2-ethylhexyl alcohol, dodecyl alcohol, ethylene glycol, diethylene glycol monoether) , Propylene glycol, etc.);
Ester of monocarboxylic acid of No. 2 with a polyol (for example, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, etc.); others, polyoxyalkylene glycol, polyoxyalkylene glycol ester, polyoxyalkylene glycol Examples include alkylene glycol ethers, phosphoric acid esters, and silicone oils.

The vegetable oil base oils include castor oil,
Rapeseed oil, olive oil, sunflower oil and the like can be used.

The above-mentioned various lubricating base oils can be prepared so as to have desired viscosity and other properties depending on the use of the lubricating oil composition. For example, by mixing various lubricating base oils, the lubricating oil for an internal combustion engine has a kinematic viscosity at 100 ° C. of ² to 30 mm ² / s, particularly 3 to 10 mm ² / s.
And the kinematic viscosity at 100 ° C. is ² to 30 mm ² / s, particularly 3 to 15 mm.
^It may be adjusted to a range of ² / s.

Examples of the sulfur-containing organic molybdenum compound constituting the lubricating oil composition of the present invention include oxymolybdenum dithiocarbamate, oxymolybdenum dithiophosphate and oxymolybdenum dithioxanthogenate. . Sulfurized oxymolybdenum dithiocarbamate is represented by the following general formula [I], sulfided oxymolybdenum dithiophosphate is represented by a general formula [II], and sulfided oxymolybdenum dithioxanthogenate is represented by a general formula [III]. General formula [I]

[0014]

Embedded image General formula [II]

[0015]

Embedded image General formula [III]

[0016]

Embedded image In the general formulas [I], [II] and [III], R ¹ and R ² are a hydrocarbon group having 1 to 30 carbon atoms,
They may be the same or different. Examples of the hydrocarbon group include an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms, a cycloalkyl group having 6 to 30 carbon atoms;
An aryl group having 30 carbon atoms.
And those substituted with an alkyl group of 4. Preferred hydrocarbon groups are alkyl groups having 3 to 24 carbon atoms, such as propyl, butyl, pentyl, hexyl,
Heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group,
Examples thereof include linear or branched alkyl groups such as a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an eicosyl group. More preferred alkyl groups are those having 3 to 20 carbon atoms in the sulfurized oxymolybdenum dithiocarbamate represented by the general formula [I], and exhibit a synergistic friction reducing effect when used in combination with an organic acid metal salt compound described below. Show. Also in the sulfurized oxymolybdenum dithiophosphate of the general formula [II], an alkyl group having 3 to 20 carbon atoms is particularly preferable from the viewpoint of a friction reducing effect. Further, in the sulfurized oxymolybdenum dithioxanthogenate represented by the general formula [III], an alkyl group having 3 to 24 carbon atoms is preferable.

In the general formulas [I], [II] and [III], x is 0.5 to 2.3, preferably 0 to 2.3.
It is. Accordingly, typical examples of the oxymolybdenum dithiocarbamate of the general formula [I] suitable for the lubricating oil composition of the present invention include oxymolybdenum dipropyl dithiocarbamate, oxymolybdenum diisopropyl dithiocarbamate, oxymolybdenum dibutyl dithiocarbamate, and oxymolybdenum dibutyl dithiocarbamate. Oxymolybdenum diisobutyl dithiocarbamate, oxymolybdenum dibutenyl dithiocarbamate, oxymolybdenum dipentyl dithiocarbamate, oxymolybdenum diisopentyl dithiocarbamate, oxymolybdenum dihexyl dithiocarbamate, oxymolybdenum diheptyl dithiocarbamate, oxymolybdenum dioctyl sulfide Oxymolybdenum sulfide (2
-Ethylhexyl) dithiocarbamate, oxymolybdenum sulfide (2-propylpentyl) dithiocarbamate, oxymolybdenum dinonyl dithiocarbamate, oxymolybdenum sulfide (2-propylhexyl)
Dithiocarbamate, oxymolybdenum didecyl dithiocarbamate, oxymolybdenum didodecyl dithiocarbamate, oxymolybdenum sulfide (2-methyldodecyl) dithiocarbamate, oxymolybdenum dihexadecyl dithiocarbamate, oxymolybdenum sulfide oxymolybdenum dioctadecyl dithiocarbamate, oxymolybdenum sulfide (2- Methyloctadecyl) dithiocarbamate and the like.

Representative examples of the oxymolybdenum sulfide dithiophosphates represented by the general formula [II] include oxymolybdenum dipropyl dithiophosphate, oxymolybdenum diisopropyl dithiophosphate, oxymolybdenum dibutyl dithiophosphate, oxymolybdenum diisobutyl dithiophosphate, and oxymolybdenum sulfide. Dibutenyl dithiophosphate, oxymolybdenum dipentyl dithiophosphate, oxymolybdenum dihexyl dithiophosphate, oxymolybdenum diheptyl dithiophosphate, oxymolybdenum dioctyl dithiophosphate, oxymolybdenum dioctyl dithiophosphate, oxymolybdenum sulfide (2-ethylhexyl) dithiophosphate, oxymolybdenum dinonyl dithiophosphate , Oxymolybdenum sulfide Examples thereof include sildithiophosphate, sulfurized oxymolybdenum didodecyldithiophosphate, sulfurized oxymolybdenum dioctadecyldithiophosphate, sulfurized oxymolybdenum dioleyl dithiophosphate, and the like, and compounds having a branched alkyl group or alkenyl group.

Representative examples of the sulfurized oxymolybdenum dithioxanthogenate represented by the general formula [III] include oxymolybdenum butyl dithioxanthogenate, oxymolybdenum pentyl dithioxanthogenate, oxymolybdenum hexyl dithioxanthogenate, Oxymolybdenum sulfide heptyl dithioxanthogenate, oxymolybdenum octyl dithioxanthogenate, oxymolybdenum (2-ethylhexyl) dithioxanthogenate, oxymolybdenum nonyl dithioxanthogenate, oxymolybdenum decyl dithioxanthogenate, sulfided Oxymolybdenum decyl dithioxanthogenate, oxymolybdenum tetradecyl dithioxanthogenate, oxymolybdenum hexadecyl dithioxanthate Sulfonate, oxymolybdenum octadecyl dithiocarbamate xanthogenate sulfide, may be mentioned compounds having a molybdenum oxysulfide nonadecyl dithio xanthogenate, sulfurized oxymolybdenum eicosyl dithio xanthogenate like or branched alkyl or alkenyl groups of these.

The above general formulas [I], [II] and [III]
The sulfur-containing organic molybdenum-based compound represented by
Each of them can be used alone, but two or more kinds may be used in combination. The amount of the lubricating base oil is not limited and depends on the use of the lubricating oil composition and the type of the organic molybdenum compound.
000 ppm, preferably 200-1500 ppm
Can be used in the range. Molybdenum content is 150
If the amount is less than ppm, a synergistic effect with the organic acid and zinc dithiophosphate cannot be obtained, resulting in a problem that a friction reducing effect is lacking. On the other hand, if the amount of molybdenum exceeds 2,000 ppm, not only the effect corresponding to the increased amount cannot be obtained, but also there is a problem in solubility and there is a possibility of sedimentation.

Although the mechanism of action of such an organic molybdenum compound has not been fully elucidated, it is considered that a MoS _X coating is formed on the sliding surface under the conditions of use of the lubricating oil to reduce the coefficient of friction. It is presumed that, therefore, the lubricating oil composition of the present invention is not limited to the above molybdenum compounds as the sulfur-containing organic molybdenum compounds, but has a friction reducing effect by forming a MoS _X film or the like. If so, other compounds can be used.

Next, the organic acid used as a component of the lubricating oil composition of the present invention will be described. The organic acid in the present invention is selected from the group consisting of aliphatic sulfonic acids, aromatic sulfonic acids, aromatic carboxylic acids and aliphatic hydrocarbon-substituted phenol compounds.

The aliphatic sulfonic acid comprises an aliphatic hydrocarbon group and a sulfonic acid group, and has the general formula [IV]

[0024]

Embedded image The aromatic sulfonic acid is represented by the general formula [V], which comprises an aromatic hydrocarbon group and a sulfonic acid group.

[0025]

Embedded image It is represented by In the general formula [IV], R is an aliphatic hydrocarbon group, and in the general formula [V], R is an aliphatic hydrocarbon group and Ar is an aromatic hydrocarbon group. n represents the number of bonds of the aliphatic hydrocarbon group to the aromatic hydrocarbon group,
5, preferably an integer of 1 to 3. The aliphatic sulfonic acid has an aliphatic hydrocarbon group having 4 to 40 carbon atoms, and the aromatic sulfonic acid includes an aromatic hydrocarbon group substituted with an aliphatic hydrocarbon group having 4 to 40 carbon atoms. Is used.

The aliphatic hydrocarbon group has 4 to 40 carbon atoms.
In order to impart oil solubility, an alkyl group having 8 or more carbon atoms is preferable. Specifically, an octyl group, a nonyl group, a decyl group, a dodecyl group, a tridecyl group,
Tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, tetraxyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl and triacontyl, pentatriacontyl, octatria Contyl groups and the like can be mentioned. Among these alkyl groups, an alkyl group having 8 to 20 carbon atoms is preferable from the viewpoint of a friction reducing effect by the combined use with MoDTC, ZnDTP and the like.

The aromatic hydrocarbon group may be either a monocyclic or polycyclic fused ring, for example, benzene, naphthalene, anthracene, phenanthrene, indene,
Examples include fluorene and biphenyl.

The aliphatic sulfonic acid and the aromatic sulfonic acid are more specifically illustrated by the following general formulas [VI] to [XIII]. General formula [VI]

[0029]

Embedded image General formula [VII]

[0030]

Embedded image General formula [VIII]

[0031]

Embedded image In the general formulas [VI] to [VIII], R _{1 to} R ₃ are aliphatic hydrocarbon groups, which may be the same or different from each other. n represents the number of bonds of the aliphatic hydrocarbon group to the aromatic ring, and in each of the general formulas, n may be the same as or different from each other. As the aliphatic hydrocarbon group, the aforementioned alkyl group is preferable, and n is 1 to 5, preferably 1 to 3.
Is an integer.

As specific examples of the aliphatic sulfonic acid and the aromatic sulfonic acid, the aliphatic hydrocarbon groups of R _{1 to} R ₃ are alkyl groups, and alkyl sulfonic acids having 8 to 20 carbon atoms, and monoalkyl benzenes. Examples thereof include sulfonic acid, dialkylbenzenesulfonic acid, monoalkylnaphthalenesulfonic acid, and dialkylnaphthalenesulfonic acid. As the alkyl sulfonic acid, for example,
Octylsulfonic acid, nonylsulfonic acid, decylsulfonic acid, undecylsulfonic acid, dodecylsulfonic acid, tridecylsulfonic acid, tetradecylsulfonic acid, pentadecylsulfonic acid, hexadecylsulfonic acid, heptadecylsulfonic acid, octadecylsulfonic acid , Nonadecylsulfonic acid, eicosylsulfonic acid and the like. Examples of the monoalkylbenzenesulfonic acid and dialkylbenzenesulfonic acid include, for example, monooctylbenzenesulfonic acid, monononylbenzenesulfonic acid, monodecylbenzenesulfonic acid, monoundecylbenzenesulfonic acid, monododecylbenzenesulfonic acid, and monotridecyl. Benzenesulfonic acid, monotetradecylbenzenesulfonic acid, monopentadecylbenzenesulfonic acid, monohexadecylbenzenesulfonic acid, monoheptadecylbenzenesulfonic acid, monooctadecylbenzenesulfonic acid, monononadecylbenzenesulfonic acid, monoeicosylbenzenesulfone Acid, dioctylbenzenesulfonic acid, dinonylbenzenesulfonic acid, didecylbenzenesulfonic acid, diundecylbenzenesulfonic acid, didodecylbenzenes Acid ditridecyl benzenesulfonic acid, di tetradecyl benzenesulfonic acid,
Examples thereof include dipentadecylbenzenesulfonic acid, dihexadecylbenzenesulfonic acid, diheptadecylbenzenesulfonic acid, dioctadecylbenzenesulfonic acid, dinonadecylbenzenesulfonic acid, and dieicosylbenzenesulfonic acid. Further, examples of the monoalkylnaphthalenesulfonic acid and dialkylnaphthalenesulfonic acid include, for example, monooctylnaphthalenesulfonic acid, monononylnaphthalenesulfonic acid, monodecylnaphthalenesulfonic acid, monoundecylnaphthalenesulfonic acid, monododecylbenzenesulfonic acid, and monotrinaphthalenesulfonic acid. Decylbenzenesulfonic acid, monotetradecylbenzenesulfonic acid, monopentadecylbenzenesulfonic acid, monohexadecylbenzenesulfonic acid, monoheptadecylbenzenesulfonic acid, monooctadecylbenzenesulfonic acid,
Monononyldecylbenzenesulfonic acid, monoeicosylbenzenesulfonic acid, dioctylnaphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, didecylnaphthalenesulfonic acid, diundecylnaphthalenesulfonic acid, didodecylnaphthalenesulfonic acid, ditridecylnaphthalenesulfonic acid, di Tetradecylnaphthalenesulfonic acid,
Examples thereof include dipentadecylnaphthalenesulfonic acid, dihexadecylnaphthalenesulfonic acid, diheptadecylnaphthalenesulfonic acid, dioctadecylnaphthalenesulfonic acid, dinonadecylnaphthalenesulfonic acid, and dieicosylnaphthalenesulfonic acid. Aromatic sulfonic acids substituted with two or more alkyl groups having different carbon numbers from each other can also be used.

Further, a petroleum sulfonic acid containing alkylaryl sulfonic acid as a main component obtained by sulfonating a petroleum fraction can also be used.

The above-mentioned aliphatic sulfonic acid and aromatic sulfonic acid may be used alone or in a mixture of two or more.

As the aromatic carboxylic acid, any of a carboxylic acid having a carboxyl group in a side chain in addition to a carboxylic acid having a carboxyl group directly bonded to an aromatic ring can be used, and the following general formula [IX]

[0036]

Embedded image It is preferable to use a compound represented by the formula: General formula [IX]
In the formula, R represents an aliphatic hydrocarbon group, m and n
Is an integer of 1 to 4, respectively. As the aromatic carboxylic acid, any of monocarboxylic acid, dicarboxylic acid, and other polycarboxylic acids may be used. Specifically, there may be mentioned benzoic acid, phthalic acid, phenylacetic acid, mandelic acid and the like substituted with an aliphatic hydrocarbon group and derivatives thereof. A particularly preferred aromatic carboxylic acid for the lubricating oil composition of the present invention is salicylic acid having a hydroxyl group bonded to an aromatic ring and substituted with at least one aliphatic hydrocarbon group, and has the following general formula [ X]

[0037]

Embedded image It is represented by In the general formula [X], R ₁ is an aliphatic hydrocarbon group, n is the number of bonds of the aliphatic hydrocarbon group to the aromatic ring, and is an integer of 1 to 4.

Examples of the aliphatic hydrocarbon group include those having 4 to 4 carbon atoms.
An alkyl group of 0 is preferable, and specifically, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl , Heptadecyl group, octadecyl group, nonadecyl group,
Examples thereof include a linear or branched alkyl group such as a triacontyl group and a pentatriacontyl group. Among these alkyl groups, an alkyl group having 8 to 20 carbon atoms is particularly preferable because the friction reduction effect when used in combination with MoDTC, ZnDTP or the like is remarkable.

Accordingly, specific examples of the aliphatic hydrocarbon-substituted salicylic acid used in the lubricating oil composition of the present invention include alkyl salicylic acids such as monooctyl salicylic acid, monononyl salicylic acid, monodecyl salicylic acid, monoundecyl salicylic acid, and monododecyl. Salicylic acid, monotridecyl salicylic acid, monotetradecyl salicylic acid, monopentadecyl salicylic acid, monohexadecyl salicylic acid, monoheptadecyl salicylic acid, monooctadecyl salicylic acid, monononadecyl salicylic acid, monoeicosyl salicylic acid, dioctyl salicylic acid, dinonyl salicylate, didecyl salicylate Salicylic acid, diundecyl salicylic acid, didodecyl salicylic acid, ditridecyl salicylic acid, ditetradecyl salicylic acid, dipentadecyl salicylic acid, dihexadecyl salicyl , It may be mentioned di-heptadecyl acid, dioctadecyl acid, Gino Na decyl salicylic acid, dieicosyl salicylic acid and mixtures thereof. Further, salicylic acid substituted with two or more kinds of alkyl groups having different carbon numbers can also be used.

The alkyl salicylic acid may be a sulfurized alkyl salicylic acid, and the sulfurized alkyl salicylic acid can be exemplified by the general formula [XI]. General formula
In [XI], R ₁ and R ₂ are the aforementioned alkyl groups, which may be the same or different from each other, and x is 1 or 2.

[0041]

Embedded image Next, the aliphatic hydrocarbon-substituted phenol compound used as an organic acid as a component of the lubricating oil composition of the present invention is a phenol compound substituted with at least one aliphatic hydrocarbon group and represented by the general formula [XII ]

[0042]

Embedded image It is represented by In the general formula [XII], R is an aliphatic hydrocarbon group, and n is the number of bonds of the aliphatic hydrocarbon group to the aromatic ring, and is an integer of 1 to 4, preferably 1 or 2. M is the number of bonds of the hydroxyl group to the aromatic ring, and is 1 to 2.

Examples of the aliphatic hydrocarbon group include those having 4 to 4 carbon atoms.
An alkyl group of 0 is preferred, for example, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, heptadecyl, octadecyl, nonadecyl And a straight-chain or branched alkyl group such as an eicosyl group, a tetracosyl group, a pentacosyl group, a hexacosyl group, a heptacosyl group, an octakosyl group, a nonacosyl group, a triacontyl group and a pentatriacontyl group. From the viewpoint of the friction reducing effect by the combined use with MoDTC, ZnDTP, etc., particularly, the carbon number is 8 to
Twenty alkyl groups are preferred.

Examples of the aliphatic hydrocarbon-substituted phenol compound include an alkylphenol compound, for example, a monoalkylphenol compound, a dialkylphenol compound, and the like. Specific examples include monooctylphenol, monononylphenol, monodecylphenol, and the like.
Monoundecylphenol, monododecylphenol,
Monotridecylphenol, monotetradecylphenol, monopentadecylphenol, monohexadecylphenol, monoheptadecylphenol, monooctadecylphenol, monononadecylphenol, monoeicosylphenol, dioctylphenol, dinonylphenol, didecylphenol, diun Decylphenol, didodecylphenol, ditridecylphenol,
Examples thereof include ditetradecylphenol, dipentadecylphenol, dihexadecylphenol, diheptadecylphenol, dioctadecylphenol, and mixtures thereof. Further, a phenol compound substituted with two or more kinds of alkyl groups having different carbon numbers can also be used.

As the alkylphenol compound, a compound obtained by a sulfuration treatment can be used. The sulfurized alkylphenol compound is, for example, a compound represented by the general formula [XIII]

[0046]

Embedded image Can be exemplified. In the general formula [XIII], R ₁
And R ₂ are the aforementioned alkyl groups, which may be the same or different. n is 1-4, preferably 1-2, and x is a number 1-2.

In the lubricating oil composition of the present invention, the amount of the organic acid can be determined according to each compound and the intended use of the lubricating oil composition. 1 to 100 mmol by mole
/ Kg, preferably in the range of 1 to 80 mmol / kg. Further, based on the total weight of the lubricating oil composition, it is preferable to mix the organic acid at a ratio of 0.01 to 5% by weight, and in particular, the organic acid is added in an amount of 0.5 to 5% by weight based on 1 mol of the sulfur-containing organic molybdenum compound. 30 mol, preferably 0.1 mol.
By using 5 to 25 moles, the effect of reducing friction in a high temperature range can be significantly improved.

The zinc dithiophosphate as a component of the lubricating oil composition of the present invention will be described. As the zinc dithiophosphate, the following general formula [XIV]

[0049]

Embedded image Can be mentioned. General formula [XIV]
In the formula, R ₁ and R ₂ are a hydrocarbon group having 3 to 20 carbon atoms, which may be the same or different. Examples of the hydrocarbon group include an alkyl group having 1 to 20 carbon atoms;
0 alkenyl group; a cycloalkyl group having 6 to 20 carbon atoms, an aryl group, an alkylaryl group, an arylalkyl group, and the like. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl. Group, hexyl group, 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, stearyl group, oleyl group, butylphenyl group, nonylphenyl group, etc. and their branched alkyls Groups. Preferred hydrocarbon groups are alkyl groups having 3 to 18 carbon atoms. The alkyl group may be either a primary or secondary alkyl group. Specifically, an isopropyl group,
Isobutyl group, secondary butyl group, pentyl group, hexyl group, 4-methyl-2-pentyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, hexadecyl Group,
It is preferable to use a compound having an alkyl group such as an octadecyl group. Accordingly, typical examples of zinc dithiophosphate include, for example, zinc diisopropyldithiophosphate, zinc diisobutyldithiophosphate, zinc di-dibutyl thiophosphate, zinc di (n-pentyl) dithiophosphate, and di (n
-Hexyl) zinc dithiophosphate, di (4-methyl-2-)
(Pentyl) zinc dithiophosphate, zinc di-n-octyldithiophosphate, zinc di (2-ethylhexyl) dithiophosphate, zinc di-n-nonyldithiophosphate, zinc di-n-decyldithiophosphate, zinc di-n-dodecyldithiophosphate, di-n
Zinc tridecyl dithiophosphate, zinc di-n-tetradecyl dithiophosphate, zinc di-n-hexadecyl dithiophosphate, zinc di-n-octadecyl dithiophosphate, and the like. As a commercial product, Paranox 15 manufactured by Exxon Chemical Co., Ltd. has a primary alkyl group as a main component, and is appropriately mixed with another commercial product having a secondary alkyl group as a main component to form a primary alkyl group. The content of the group can also be adjusted.

The amount of zinc dithiophosphate to be added to the lubricating oil composition is 100 to 2,000 ppm, preferably 200 to 1,800 ppm in terms of phosphorus. In particular, for a molybdenum content of 250 ppm, a phosphorus content of 250 to
1,800 ppm, preferably 500 to 1,500 p
When used at a ratio of pm, a remarkable effect on reduction of friction at low temperatures can be obtained. Therefore, the mixing ratio (molar ratio) of (a) a sulfur-containing organic molybdenum compound, (b) an organic acid, and (c) zinc dithiophosphate is represented by (a):
(B): (c) = 1.5 to 5.5: 1 to 30: 5 to 3
0, preferably (a) :( b) :( c) = 1.5-
By setting the ratio in the range of 5.5: 1 to 30:10 to 30, the friction characteristics can be improved without excess or deficiency from a low temperature range to a high temperature range.

According to the present invention, as described above, based on the weight of the lubricating oil composition with respect to the lubricating oil base oil, a) the sulfur-containing organic molybdenum compound is used in an amount of 150 to
2,000 ppm, b) 1-100 mmol /
kg and c) 100 parts by weight of zinc dithiophosphate as phosphorus
It is possible to provide a lubricating oil composition containing up to 2,000 ppm. In addition, if necessary, a viscosity index improver, an ashless dispersant, an antioxidant, an extreme pressure agent, an antiwear agent, a metal deactivator, a pour point depressant, a corrosion inhibitor, and other friction modifiers Etc. can be appropriately selected and blended.

Examples of the viscosity index improver include polymethacrylates, polyisobutylenes, ethylene-propylene copolymers, and styrene-butadiene hydrogenated copolymers. ~
It is used in a proportion of 35% by weight.

Examples of the ashless dispersant include polybutenyl succinimide type, polybutenyl succinamide type,
There are benzylamine type and succinate type,
These are usually used at a ratio of 0.05 to 7% by weight.

Examples of the antioxidant include amine antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated phenyl-α-naphthylamine; 2,6-di-t-butylphenol;
Examples thereof include phenolic antioxidants such as' -methylenebis- (2,6-di-t-butylphenol) and the like, which are usually used at a ratio of 0.05 to 5% by weight.

The extreme pressure agent includes, for example, dibenzyl sulfide, dibutyl disulfide and the like, and these are usually used at a ratio of 0.05 to 3% by weight.

Examples of the metal deactivator include benzotriazole, benzotriazole derivatives, thiadiazole, thiadiazole derivatives and the like, which are usually used in a proportion of 0.01 to 3% by weight.

Examples of the pour point depressant include ethylene-vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene and the like. These are usually used at a ratio of 0.1 to 10% by weight.

Examples of the antiwear agent include a phosphoric ester, an acidic phosphoric ester, a phosphite, an acidic phosphite, a sulfur compound and the like.
These are usually used at a ratio of 0.01 to 5% by weight.

As the other additives, any additives which do not inhibit the action of the sulfur-containing organic molybdenum compound, organic acid and zinc dithiophosphate of the present invention can be arbitrarily selected and used.

The sulfur-containing organic molybdenum compound, organic acid and zinc dithiophosphate of the present invention can be used in the form of being dissolved in a solvent such as mineral oil, and can also be used as a component of an additive package.

As a preferred embodiment of the present invention,

(1) a lubricating base oil, a) a sulfur-containing organic molybdenum compound having an alkyl group having 3 to 20 carbon atoms, b) an aliphatic sulfonic acid having 8 to 20 carbon atoms, at least one fat Aromatic sulfonic acid substituted with an aromatic hydrocarbon group, selected from the group consisting of salicylic acid substituted with at least one aliphatic hydrocarbon group and a phenol compound substituted with at least one aliphatic hydrocarbon group. A lubricating oil composition comprising: at least one organic acid; and c) zinc dithiophosphate having an alkyl group having 3 to 18 carbon atoms.

(2) For lubricating base oil, at least one organic acid selected from the group consisting of a) a sulfur-containing organic molybdenum compound, b) alkylbenzene sulfonic acid, dinonyl naphthalene sulfonic acid, alkyl salicylic acid and alkyl phenol And c) a lubricating oil composition comprising zinc dialkyldithiophosphate,

(3) Based on the weight of the lubricating oil composition, based on the lubricating oil composition, a) oxymolybdenum sulfide di (2-ethylhexyl) dithiocarbamate in an amount of 150 to 1,
500 ppm, b) 1 to 50 mmol of alkylbenzenesulfonic acid
/ Kg and c) a lubricating oil composition comprising 150 to 2,000 ppm of zinc di (2-ethylhexyl) dithiophosphate in terms of phosphorus amount,

(4) Based on the weight of the lubricating oil composition, based on the lubricating oil composition, a) oxymolybdenum sulfide di (2-ethylhexyl) dithiocarbamate in an amount of 150 to 1,
500 ppm, b) 1 to 50 mmol / kg of zinc alkylsalicylate
And c) a lubricating oil composition containing zinc di (2-ethylhexyl) dithiophosphate in an amount of from 150 to 2,000 ppm in terms of phosphorus.

(5) The lubricating oil compositions of (1) to (4) are further added with a viscosity index improver, an ashless dispersant, an antioxidant, an extreme pressure agent, a pour point depressant, an antiwear agent, and a metal. There is provided a lubricating oil composition comprising at least one additive selected from the group consisting of deactivators.

[0067]

Next, the present invention will be described more specifically with reference to examples and comparative examples.

The methods for evaluating the performance of the refined mineral oil, the sulfur-containing organic molybdenum compound, the organic acid, zinc dithiophosphate and the lubricating oil composition used in the examples and comparative examples are as follows. Lubricating base oil Refined mineral oil (100 neutral oil) (Kinematic viscosity ($ 100
° C): 4.2 mm ² / s) Raffinate sulfur-containing organic molybdenum compound obtained by extracting a lubricating oil fraction obtained by vacuum distillation of paraffinic crude oil by distillation under reduced pressure with a phenol solvent (1) MoDTC: Oxymolybdenum sulfide (2-
Ethylhexyl) dithiocarbamate (Sakura Lube 100 manufactured by Asahi Denka Kogyo Co., Ltd.) (2) MoDTP: oxymolybdenum sulfide (2-
(Ethylhexyl) dithiophosphate (Sakura Lube 300 manufactured by Asahi Denka Kogyo Co., Ltd.) Organic acids Shown in Tables 1-2. Zinc dithiophosphate ZnDTP: Zinc di (2-ethylhexyl) dithiophosphate (5660 manufactured by Oroa Co., Ltd.) Lubricating oil composition performance evaluation method Friction coefficient measurement method Reciprocating friction tester (SRV friction tester)
The friction coefficient was measured under the following conditions.

Friction material: steel (SUJ-2) / steel (SU
J-2), cylinder / desk Temperature: 80 ° C., 120 ° C. Load: 400 N Amplitude: 50 Hz Time: 15 min The average of the last 3 minutes of the measurement for 15 minutes was taken as the friction coefficient.

Friction coefficient stability The stability of the friction coefficient was evaluated based on the fluctuation range of the friction coefficient.

Examples 1 to 3 In a refined mineral oil, M was used as a sulfur-containing organic molybdenum compound.
500 ppm of oDTC was blended as Mo amount, and alkylbenzenesulfonic acid and ZnDTP were blended at the ratios shown in Table 1. When the obtained lubricating oil composition was subjected to the above-described performance evaluation, the friction coefficient at 25 ° C., 80 ° C., and 120 ° C. was low, and the friction coefficient stability was good.

Examples 4 to 6 As the organic acid, dinonylnaphthalenesulfonic acid (Example 4), nonylphenol (Example 5) and alkylsalicylic acid (Example 6) are used in place of alkylbenzenesulfonic acid, as shown in Table 1. The lubricating oil composition was obtained in the same manner as in Example 1 except that each was blended. Table 1 shows the results of the performance evaluation. 25 ° C, 80 ° C and 120
The friction coefficient was low and the friction coefficient stability was good at any temperature of ° C.

Example 7 A lubricating oil composition was prepared in the same manner as in Example 1 except that MoDTP was used instead of MoDTC as the sulfur-containing organic molybdenum compound. Performance almost equivalent to that in the case of using MoDTC was obtained.

Examples 8 to 10 The amounts of MoDTC were 250 ppm (Example 8), 150 ppm (Example 9) and 1,500 ppm
A lubricating oil composition was obtained in the same manner as in Example 1 except that the lubricating oil composition was changed to pm (Example 10). Table 1 shows the results of the performance evaluation.

Example 11 As shown in Table 1, the amount of ZnDTP was 1
A lubricating oil composition was obtained in the same manner as in Example 1 except that the amount was reduced to 00 ppm. The performance evaluation is shown in Table 1.

Comparative Example 1 A lubricating oil composition was prepared by mixing only MoDTC with refined mineral oil, and its performance was evaluated. The coefficient of friction is high at temperatures of 25 ° C. and 80 ° C., especially at low temperatures of 25 ° C. Further, the friction coefficient stability at a high temperature of 120 ° C. is poor.

Comparative Example 2 ZnDTP was added to the lubricating oil composition of Comparative Example 1 at 1,000 pp.
m, and the performance was evaluated. At a high temperature of 120 ° C., both the coefficient of friction and its stability were poor.

Comparative Examples 3 to 7 As shown in Table 2, alkyl benzene sulfonic acid, dinonyl naphthalene sulfonic acid, nonyl phenol, salky salicylic acid, and stearic acid were added to purified mineral oil using ZnDT.
Each of P and P was blended in the ratio shown in the same table. As a result of the performance evaluation, the friction coefficient was high and the friction characteristics were insufficient. In particular, stearic acid (fatty acid) is MoDTC, ZnDTP
Low friction was not obtained at 80 ° C. and 120 ° C.

Comparative Examples 8 to 11 As shown in Table 2, MoDTC was added to refined mineral oil, alkylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid,
Nonylphenol and alkyl salicylic acid were each blended, but ZnDTP was not used. 25 ° C for all
No low coefficient of friction was obtained at low temperature.

COMPARATIVE EXAMPLE 12 As shown in Table 2, 30.0 mmol / kg of only alkylbenzenesulfonic acid was blended with refined mineral oil and subjected to performance evaluation. At any of 25 ° C., 80 ° C. and 120 ° C. No low coefficient of friction was obtained.

Comparative Examples 13 and 14 As shown in Table 2, each component was blended to obtain a lubricating oil composition. Even when MoDTC, alkylbenzene sulfonic acid and ZnDTP were used in combination, when MoDTC was reduced, the friction coefficient at 25 ° C. increased (Comparative Example 13),
Similarly, when the amount of ZnDTP was reduced, the friction coefficient at 25 ° C. was increased (Comparative Example 14).

Comparative Example 15 A lubricating oil composition was prepared in the same manner as in Example 1 except that oxymolybdenum monoglyceride was used as the organic molybdenum-based compound containing no sulfur instead of MoDTC. As a result of the performance evaluation, a sufficient friction reducing effect was not obtained as shown in Table 2.

[0083]

[Table 1]

[0084]

[Table 2]

According to the examples and comparative examples, MoD
When an effective amount of each of the three components such as TC and a specific organic acid and ZnDTP is blended, 25 ° C., 80 ° C. and 120 ° C.
Has a low coefficient of friction and a good stability of the coefficient of friction. Among organic acids, aliphatic carboxylic acids are converted to MoDT.
It was also found that a low friction lubricating oil could not be obtained even when used in combination with C or the like.

[0086]

According to the present invention, a synergistic effect can be obtained by combining (a) a sulfur-containing organic molybdenum compound, (b) a specific organic acid and (c) zinc dithiophosphate as essential components in a specific amount. a), (b) and (c) reduce the effective lower limit of each additive and
It is possible to provide a lubricating oil composition having a low coefficient of friction and a high coefficient of friction stability over a wide temperature range from a low temperature range of 5 to 120 ° C to a high temperature range.

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Claims (4)

[Claims] 1. The lubricating base oil is selected from the group consisting of: a) a sulfur-containing organic molybdenum compound; b) an aliphatic sulfonic acid, an aromatic sulfonic acid, an aromatic carboxylic acid, and an aliphatic hydrocarbon-substituted phenol compound. A lubricating oil composition comprising at least one organic acid and c) zinc dithiophosphate. 2. The lubricating oil composition according to claim 1, wherein the aromatic sulfonic acid is an aliphatic hydrocarbon-substituted benzenesulfonic acid and / or an aliphatic hydrocarbon-substituted naphthalenesulfonic acid. 3. The lubricating oil composition according to claim 1, wherein the aromatic carboxylic acid is an aliphatic hydrocarbon-substituted salicylic acid. 4. The compounding amount of the sulfur-containing organic molybdenum-based compound is 150 to 2,000 ppm in terms of molybdenum, and the compounding amount of the organic acid is 1 to 1, based on the weight of the lubricating oil composition.
The compounding amount of 00 mmol / kg and zinc dithiophosphate is 100 to 2,000 ppm as a phosphorus amount.
The lubricating oil composition according to the above item.