JP2012246362A - Lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating oil composition that has a low molybdenum content and yet exhibits excellent friction reduction.SOLUTION: The lubricating oil composition comprises a lubricant base oil, (A) a phosphate metal salt represented by general formula (1) and (B) an organomolybdenum compound having a ratio of the molybdenum element to the sulfur element of 1:≥3.5. In the formula, Rto Rare the same or different and are each a 1-30C hydrocarbon group, or a 1-30C alkyl or alkenyl group, or an alkylthioethyl group comprising a 1-30C alkyl group; X, X, Xand Xare each sulfur or oxygen; either one or both of Xand Xare oxygen; either one or both of Xand Xare oxygen; and Y is a metal element.

Description

  The present invention relates to a novel lubricating oil composition, and in particular, a lubricating oil composition having excellent friction reducing properties, which is produced by blending a metal salt of a phosphate ester and a molybdenum friction modifier having a specific structure into a base oil. Related to things. In particular, the present invention relates to a lubricating oil composition suitably used as a lubricating oil for an internal combustion engine.

Conventionally, lubricating oil is used for an internal combustion engine, an automatic transmission, grease, and the like in order to make the operation smooth. In particular, lubricating oil (engine oil) for internal combustion engines is required to have high performance as the performance of the internal combustion engine increases, the output increases, and the operating conditions become severe. Therefore, in order to satisfy such required performance, conventional engine oils are blended with various additives such as antiwear agents, metallic detergents, ashless dispersants, antioxidants (for example, Patent Documents 1 to 3). See). In addition, fuel-saving engine oils have a large energy loss in the frictional part where the lubricating oil is involved. Therefore, friction modifiers (FM: friction modifier) and other additives are combined to reduce friction loss and fuel consumption. Lubricating oil is also used (see, for example, Patent Document 4). Of these, friction reduction technology using zinc dialkyldithiophosphate (ZDTP) and a molybdenum compound is the most common, but in this case, excellent friction reduction performance can be obtained unless a relatively large amount of molybdenum compound is added. Absent.
Furthermore, when both molybdenum compounds and ZDTP are used in lubricating oils for internal combustion engines, there is a problem that the exhaust gas aftertreatment system is contaminated and its purification efficiency is lowered because it is metallic. Further, when a large amount of molybdenum compound is used, there is a possibility that deposits increase due to deterioration and the sealing material may be adversely affected. It is desired that the use of the molybdenum compound exhibits a sufficient friction reducing effect with as little amount as possible.

JP 2001-279287 A JP 2002-129182 A Japanese Patent Laid-Open No. 08-302378 Japanese Patent Laid-Open No. 06-306384

  The present invention provides a lubricating oil composition suitably used as a lubricating oil for internal combustion engines, automatic transmissions, greases, etc., particularly as a lubricating oil for an internal combustion engine, which can provide excellent friction reduction even at a low concentration of molybdenum. Objective.

（式中のＲ_１〜Ｒ_４は炭素数１〜３０の炭化水素基または炭素数１〜３０のアルキル基あるいはアルケニル基、または炭素数１〜３０のアルキル基からなるアルキルチオエチル基であり、同一でも異なっていてもよい。Ｘ_１、Ｘ_２、Ｘ_３およびＸ_４は、それぞれ硫黄または酸素を示し、Ｘ_１およびＸ_２はどちらか一方が酸素、または全て酸素、Ｘ_３およびＸ_４はどちらか一方が酸素、または全て酸素であり、Ｙは金属元素を示す。） As a result of earnest research on the above problems, the present inventor has completed the present invention.
That is, according to the present invention, the lubricating base oil contains (A) a metal salt of a phosphate ester represented by the general formula (1) and (B) an organic whose ratio of molybdenum element to sulfur element is 1: 3.5 or more. The present invention relates to a lubricating oil composition containing a molybdenum compound.

(Wherein R _{1 to} R ₄ are a hydrocarbon group having 1 to 30 carbon atoms, an alkyl group or alkenyl group having 1 to 30 carbon atoms, or an alkylthioethyl group composed of an alkyl group having 1 to 30 carbon atoms, and the same X ₁ , X ₂ , X ₃ and X ₄ represent sulfur or oxygen, respectively, X ₁ and X ₂ are either oxygen or all oxygen, and X ₃ and X ₄ are either One of them is oxygen or all oxygen, and Y represents a metal element.)

  According to the present invention, with a small amount of molybdenum, it is possible to suppress the deterioration of the performance of the lubricating oil, reduce the adverse effect on the exhaust gas after-treatment device, and sufficiently reduce the friction under mixed lubrication conditions at low cost. It is possible to provide a lubricating oil composition that is excellent in reducing friction loss and reducing fuel consumption.

  The present invention will be described below.

  Examples of the lubricating base oil used in the lubricating oil composition of the present invention (hereinafter referred to as “the lubricating base oil according to the present invention”) include mineral base oils and / or synthetic base oils.

  As the mineral oil base oil, for example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and / or vacuum distillation is subjected to solvent removal, solvent extraction, hydrocracking, hydroisomerization, solvent dewaxing, Paraffinic mineral oil, or normal paraffinic base oil, isoparaffinic base oil, etc., refined by combining one or more of purification processes such as catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment alone Is mentioned.

  As a preferable example of the mineral base oil, the following base oils (1) to (7) and / or lubricating oil fractions recovered from the base oils (1) to (7) are obtained by a predetermined refining method. The base oil obtained by refine | purifying and collect | recovering lubricating oil fractions can be mentioned.

(1) Distilled oil (WVGO) by distillation under reduced pressure of paraffin base crude oil and / or mixed base crude oil at atmospheric distillation residue
(2) Wax (slack wax, etc.) obtained by a lubricant dewaxing process and / or synthetic wax (Fischer-Tropsch wax, GTL wax, etc.) obtained by a gas-to-liquid (GTL) process, etc.
(3) One or two or more mixed oils selected from base oils (1) to (2) and / or mild hydrocracking treatment oils of the mixed oils (4) selected from base oils (1) to (3) Two or more kinds of mixed oils (5) Paraffinic crude oil and / or degassed oil (DAO) of vacuum distillation residual oil of atmospheric distillation residue of mixed base crude oil
(6) Mild hydrocracking treatment oil (MHC) of base oil (5)
(7) Two or more mixed oils selected from base oils (1) to (6).

  The above-mentioned predetermined purification methods include hydrorefining such as hydrocracking and hydrofinishing; solvent refining such as furfural solvent extraction; dewaxing such as solvent dewaxing and catalytic dewaxing; acid clay and activated clay White clay purification; chemical (acid or alkali) cleaning such as sulfuric acid cleaning and caustic soda cleaning is preferable. In the present invention, one of these purification methods may be performed alone, or two or more may be combined. Moreover, when combining 2 or more types of purification methods, the order in particular is not restrict | limited, It can select suitably.

As the mineral base oil, the base oil (8) shown below is particularly preferable.
(8) Hydrocracking a base oil selected from the base oils (1) to (7) or a lubricating oil fraction recovered from the base oil, and recovering the product or the product by distillation or the like Hydrocracked mineral oil obtained by performing dewaxing treatment such as solvent dewaxing or catalytic dewaxing on the lubricating oil fraction, or by performing distillation after the dewaxing treatment.
In addition, when obtaining the lubricating base oil of (8) above, a solvent refining treatment and / or a hydrofinishing treatment step may be further provided as necessary at a convenient step.

  In addition, the sulfur content in the mineral oil base oil is not particularly limited, but from the viewpoint of further improving thermal and oxidation stability and reducing sulfur content, the sulfur content should be 100 mass ppm or less. Is preferably 50 ppm by mass or less, more preferably 10 ppm by mass or less, and particularly preferably 5 ppm by mass or less.

Further, it is preferred that the% C _A of the mineral base oil is 2 or less, more preferably 1 or less, more preferably 0.8 or less, particularly preferably 0.5 or less, and most preferably 0. % If C _A is more than 2, the viscosity - temperature characteristic, thermal and oxidation stability and fuel efficiency tends to decrease.

  A synthetic base oil may be used as the lubricating base oil according to the present invention. Synthetic base oils include poly α-olefins or hydrides thereof, isobutene oligomers or hydrides thereof, isoparaffins, alkylbenzenes, alkylnaphthalenes, diesters (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate , Di-2-ethylhexyl sebacate, etc.), polyol esters (trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate, etc.), polyoxyalkylene glycol, dialkyldiphenyl ether, Examples thereof include polyphenyl ether, and among them, poly α-olefin is preferable. As the poly α-olefin, typically, an oligomer or co-oligomer (1-octene oligomer, decene oligomer, ethylene-propylene co-oligomer, etc.) having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms, and those. Of the hydrides.

The viscosity index of the lubricating base oil according to the present invention is preferably 110 or more. More preferably, it is 120 or more, More preferably, it is 125 or more. Moreover, it is preferable that it is 160 or less. When the viscosity index is less than 110, not only the viscosity-temperature characteristics, thermal / oxidative stability, and volatilization prevention properties deteriorate, but also the friction coefficient tends to increase, and the wear prevention properties tend to decrease. . On the other hand, when the viscosity index exceeds 160, the low-temperature viscosity characteristics tend to deteriorate.
In addition, the viscosity index as used in the field of this invention means the viscosity index measured based on JISK2283-1993.

The kinematic viscosity at 100 ° C. of the lubricating base oil according to the present invention is preferably 10 mm ² / s or less, more preferably 6 mm ² / s or less, still more preferably 5.0 mm ² / s or less, particularly preferably 4. 5 mm ² / s or less, and most preferably not more than 4.2 mm ² / s. On the other hand, the kinematic viscosity is preferably 1 mm ² / s or more, more preferably 1.5 mm ² / s or more, further preferably 2 mm ² / s or more, and particularly preferably 2.5 mm ² / s. As described above, it is most preferably 3 mm ² / s or more. The kinematic viscosity at 100 ° C. here refers to the kinematic viscosity at 100 ° C. as defined in ASTM D-445. If the 100 ° C. kinematic viscosity of the lubricating base oil component exceeds 6 mm 2 / ^s, the low temperature viscosity characteristics are deteriorated, and there may not be obtained sufficient fuel economy, in the case of less than 1 mm 2 / ^s Since the formation of an oil film at the lubrication site is insufficient, the lubricity is inferior, and the evaporation loss of the lubricating oil composition may increase.

  In the lubricating oil composition of the present invention, the lubricating base oil according to the present invention may be used alone, and the lubricating base oil according to the present invention may be one or more of other base oils. You may use together. When the lubricating base oil according to the present invention is used in combination with another base oil, the ratio of the lubricating base oil according to the present invention in the mixed base oil is preferably 30% by mass or more. 50% by mass or more is more preferable, and 70% by mass or more is still more preferable.

Although it does not restrict | limit in particular about the other base oil used together with the lubricating base oil which concerns on this invention, As a mineral oil type | system | group base oil, kinematic viscosity in 100 degreeC exceeds 10 mm < ² > / s, for example, 200 mm < ² > / s or less solvent refined mineral oil, hydrocracked mineral oil, hydrorefined mineral oil, solvent dewaxed mineral oil and the like. Examples of the synthetic base oil include synthetic base oils having a kinematic viscosity at 100 ° C. outside the range of 1 to 10 mm ² / s.

  The component (A) in the lubricating oil composition of the present invention is a metal salt of a phosphate represented by the general formula (1).

Here, R _{1 to} R ₄ in the general formula (1) are alkylthios composed of a hydrocarbon group having 1 to 30 carbon atoms, an alkyl group or alkenyl group having 1 to 30 carbon atoms, or an alkyl group having 1 to 30 carbon atoms. An ethyl group, which may be the same or different. X ₁ , X ₂ , X ₃ and X ₄ each represent sulfur or oxygen, X ₁ and X ₂ are either oxygen or all oxygen, X ₃ and X ₄ are either oxygen or all Oxygen and Y represents a metal element.

Specific examples of the hydrocarbon group having 1 to 30 carbon atoms represented by R _{1 to} R ₄ include an alkyl group, a cycloalkyl group or an alkenyl group, an alkyl-substituted cycloalkyl group, an aryl group, and an alkyl-substituted aryl group. And arylalkyl groups.

  Examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and the like. Group, hexadecyl group, heptadecyl group, octadecyl group and other alkyl groups (these alkyl groups may be linear or branched).

As said cycloalkyl group, C5-C7 cycloalkyl groups, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, can be mentioned, for example.
Examples of the alkylcycloalkyl group include a methylcyclopentyl group, a dimethylcyclopentyl group, a methylethylcyclopentyl group, a diethylcyclopentyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a methylethylcyclohexyl group, a diethylcyclohexyl group, a methylcycloheptyl group, Examples thereof include an alkylcycloalkyl group having 6 to 11 carbon atoms such as a dimethylcycloheptyl group, a methylethylcycloheptyl group, and a diethylcycloheptyl group (the substitution position of the alkyl group with the cycloalkyl group is also arbitrary).

  Examples of the alkenyl group include butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, An alkenyl group such as an octadecenyl group (these alkenyl groups may be linear or branched, and the position of the double bond is also optional).

As said aryl group, aryl groups, such as a phenyl group and a naphthyl group, can be mentioned, for example.
Examples of the alkylaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, and decylphenyl group. And an alkylaryl group having 7 to 18 carbon atoms such as undecylphenyl group and dodecylphenyl group (the alkyl group may be linear or branched, and the substitution position on the aryl group is arbitrary). it can.
Examples of the arylalkyl group include arylalkyl groups having 7 to 12 carbon atoms such as benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, phenylpentyl group, and phenylhexyl group (these alkyl groups are linear). Or may be branched).

_R 1 above hydrocarbon group having 1 to 30 carbon atoms represented by the to R _4, preferably an alkyl group or an aryl group having 6 to 24 carbon atoms having 1 to 30 carbon atoms, more preferably 3 carbon atoms -18 alkyl group, most preferably a linear alkyl group having 4-8 carbon atoms.

Specific examples of the metal represented by Y include alkali metals such as lithium, sodium, potassium and cesium, alkaline earth metals such as calcium, magnesium and barium, zinc, copper, iron, lead, nickel, silver, Examples include heavy metals such as manganese and molybdenum. Of these, alkaline earth metals such as zinc, molybdenum and calcium are preferred. Zinc is particularly preferable.
In addition, as the metal salt of the phosphorus compound, the coordination number of the phosphorus compound varies depending on the valence of the metal. For example, in divalent zinc and calcium, two phosphorus compounds coordinate to one metal atom. It is thought to form a complex.

  In the lubricating oil composition of the present invention, the content of the component (A) is preferably 0.005% by mass or more, more preferably 0.02% by mass or more, and particularly preferably 0.02% by mass or more, based on the total amount of the composition. Preferably, the content is 0.05% by mass or more, while the content thereof is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and particularly preferably 0.1% by mass. It is as follows. When the content of the component (A) is less than 0.005% by mass as the phosphorus element, there is no effect on the wear resistance, and when it exceeds 0.5% by mass, it is added to the exhaust gas aftertreatment device with phosphorus. Since there are concerns about adverse effects, they are not preferable.

Of the component (A) in the present invention, the sulfur-containing compound can also be contained within the range of the phosphorus element amount, but preferably the content is in terms of elemental sulfur, The content is preferably 0.1% by mass or less, more preferably 0.08% by mass or less.
It is most preferable not to contain a sulfur-containing compound in order to greatly improve the base number maintenance property under the NOx atmosphere and to exhibit the friction reducing effect of the present invention.

Component (B) in the lubricating oil composition of the present invention is an organic molybdenum compound in which the ratio of molybdenum element to sulfur element is 1: 3.5 or more.
Examples of the organic molybdenum compound used as the component (B) include (B1) molybdenum sulfide dithiocarbamate and (B2) molybdenum sulfide dithiophosphate. Moreover, (B3) oil-soluble trinuclear molybdenum-sulfur compound can be mentioned.

  (B1) Molybdenum dithiocarbamate in the present invention is an organic molybdenum compound represented by the following general formula (2), wherein the ratio of sulfur element to molybdenum element in the compound is 3.5 or more.

(2) ^wherein, R ^1, R 2, ^{R 3} and ^{R 4} may be the same or different, carbon atoms respectively 2 to 24, preferably an alkyl group carbon atoms or 4 to 13 having 6 to 24 carbon atoms , Preferably a hydrocarbon group such as an aryl group having 8 to 15 carbon atoms (including an alkylaryl group). X ¹ , X ² , X ³ and X ⁴ may be the same or different and each represents a sulfur atom or an oxygen atom.

  Preferred examples of the alkyl group include ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, A hexadecyl group, a heptadecyl group, an octadecyl group, etc. are mentioned, These may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched. Preferred examples of (alkyl) aryl groups include phenyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, octylphenyl, nonylphenyl, decylphenyl, Examples thereof include a decylphenyl group and a dodecylphenyl group, and the alkyl group may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched. Further, these (alkyl) aryl groups include all substituted isomers in which the substitution position of the alkyl group to the aryl group is different.

  (B1) Specific examples of molybdenum dithiocarbamate sulfide include molybdenum diethyldithiocarbamate, molybdenum dipropyldithiocarbamate, molybdenum dibutyldithiocarbamate, molybdenum dipentyldithiocarbamate, molybdenum dipentyldithiocarbamate, molybdenum dihexyldithiocarbamate, and molybdenum dioctyldithiocarbamate. , Molybdenum didecyl dithiocarbamate sulfide, molybdenum didodecyl dithiocarbamate sulfide, molybdenum di (butylphenyl) dithiocarbamate sulfide, molybdenum di (nonylphenyl) dithiocarbamate sulfide, sulfurized oxymolybdenum diethyldithiocarbamate, sulfurized oxymolybdenum dipropyldithiocarbamate, sulfurized oxymolybdenum dibutyldithio Carbamate, sulfide Xylmolybdenum dipentyldithiocarbamate, sulfurized oxymolybdenum dihexyldithiocarbamate, sulfurized oxymolybdenum dioctyldithiocarbamate, sulfurized oxymolybdenum didecyldithiocarbamate, sulfurized oxymolybdenum didodecyldithiocarbamate, sulfurized oxymolybdenum di (butylphenyl) dithiocarbamate, sulfurized oxymolybdenum di (nonylphenyl) ) Dithiocarbamate (the alkyl group may be linear or branched, and the bonding position of the alkyl group of the alkylphenyl group is arbitrary), and mixtures thereof. As these molybdenum sulfide dithiocarbamates, compounds having hydrocarbon groups having different carbon numbers and / or structures in one molecule can also be preferably used.

  The (B2) molybdenum sulfide dithiophosphate in the present invention is an organic molybdenum compound represented by the following general formula (3), wherein the ratio of the sulfur element to the molybdenum element in the compound is 3.5 or more.

In the above formula (3), R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each have 2 to 30 carbon atoms, preferably 5 to 18 carbon atoms, more preferably 5 to 12 carbon atoms. Or a hydrocarbon group such as an aryl group having 6 to 18 carbon atoms (including an alkylaryl group). Y ¹ , Y ² , Y ³ and Y ⁴ may be the same or different and each represents a sulfur atom or an oxygen atom.

  Preferred examples of the alkyl group include ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, A hexadecyl group, a heptadecyl group, an octadecyl group, etc. are mentioned, These may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched. Preferred examples of (alkyl) aryl groups include phenyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, octylphenyl, nonylphenyl, decylphenyl, Examples thereof include a decylphenyl group and a dodecylphenyl group, and the alkyl group may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched. Furthermore, these (alkyl) aryl groups include all substituted isomers having different substitution positions of alkyl groups on aryl groups.

  (B2) Specific examples of the molybdenum sulfide dithiophosphate include molybdenum sulfide diethyldithiophosphate, molybdenum dipropyldithiophosphate, molybdenum dibutyldithiophosphate, molybdenum dipentyldithiophosphate, molybdenum dihexyldithiophosphate, molybdenum dioctyldithiophosphate. , Molybdenum didecyl dithiophosphate, Molybdenum didodecyl dithiophosphate, Molybdenum di (butylphenyl) dithiophosphate, Molybdenum di (nonylphenyl) dithiophosphate, Oxymolybdenum diethyldithiophosphate, Oxymolybdenum dipropyldithiophosphate, Oxymolybdenum dibutyldithio Phosphate, sulfide Xylmolybdenum dipentyldithiophosphate, sulfurized oxymolybdenum dihexyldithiophosphate, sulfurized oxymolybdenum dioctyldithiophosphate, sulfurized oxymolybdenum didecyldithiophosphate, sulfurized oxymolybdenum didodecyldithiophosphate, sulfurized oxymolybdenum di (butylphenyl) dithiophosphate, sulfurized oxymolybdenum di (nonylphenyl) ) Dithiophosphate (the alkyl group may be linear or branched, and the bonding position of the alkyl group of the alkylphenyl group is arbitrary), and mixtures thereof. As these molybdenum sulfide dithiophosphates, compounds having hydrocarbon groups having different carbon numbers and / or structures in one molecule can be preferably used.

The (B3) oil-soluble trinuclear molybdenum-sulfur compound in the present invention is an organic molybdenum compound represented by the following general formula (4), and the ratio of sulfur element to molybdenum element in the compound is 3.5 or more. It is a compound of this.
_{Mo 3 S k L n Q z} (4)

  In formula (4), L is a ligand having an organic group having a sufficient number of carbon atoms to dissolve or disperse the compound in oil, and n is 1 to 4. When n is 2 to 4, L may be the same or different. K is 4-7, Q is selected from the group of neutral electron donating compounds such as water, amines, alcohols, phosphines, and ethers, z is 0-5, and a non-stoichiometric amount. Contains a value. When z is 2 to 5, Q may be the same or different.

  L is -XR,-(X1) (X2) CR,-(X1) (X2) CYR,-(X1) (X2) CN (R1) (R2), or-(X1) (X2) P It can be independently selected from the group consisting of (OR1) (OR2) and mixtures thereof and perthio derivatives thereof. Here, X, X1, X2 and Y are independently selected from the group consisting of oxygen and sulfur, and R, R1 and R2 are independently selected from hydrogen and an organic group (which may be the same or different). Preferably, the organic group is a hydrocarbon group such as alkyl (eg, alkyl in which the carbon atom bonded to the rest of the ligand is primary, secondary or tertiary), aryl, substituted aryl and ether groups. It is. More preferably, all ligands are the same.

  The organic group of the ligand must have a sufficient number of carbon atoms to dissolve or disperse the compound in the oil. For example, the number of carbon atoms in each group is generally 1 to 100, preferably 1 to 30, and more preferably 4 to 20. Preferred ligands include dialkyldithiophosphates, alkylxanthates, and dialkyldithiocarbamates, of which dialkyldithiocarbamates are particularly preferred. Organic ligands containing two or more of the above functional groups can also function as ligands and bind one or more cores. For the formation of the compounds of the present invention, it is preferred to select a ligand with a suitable charge to balance the core charge.

As component (B), molybdenum sulfide dithiocarbamate, molybdenum sulfide dithiophosphate, and an oil-soluble trinuclear molybdenum-sulfur compound can be used alone, but molybdenum sulfide dithiocarbamate is more preferable in that it does not contain the effect and phosphorus. . An oil-soluble triangular molybdenum-sulfur compound containing no phosphorus compound in the ligand is also preferred. More preferably, the ligand is a dialkyldithiocarbamate.
However, in view of performance, it is also effective to use (B2) molybdenum sulfide dithiocarbamate in combination with (B2) molybdenum sulfide dithiophosphate. In this case, the ratio of the content of the component (B1) to the total content of the components (B1) and (B2) is preferably 50 to 95% by mass, more preferably 60 to 95% by mass in terms of molybdenum element. %, More preferably 70 to 95% by mass.

  In the lubricating oil composition of the present invention, the ratio of the molybdenum element and the sulfur element in the component (B) needs to be 3.5 or more, preferably 4 or more, with respect to the molybdenum element 1. More preferably, it is 5 or more. When the ratio of the sulfur element to the molybdenum element is less than 3.5, the low friction property is lowered.

  The content of the component (B) in the lubricating oil composition of the present invention is preferably 10 ppm by mass or more, more preferably 50 ppm in terms of the amount of molybdenum element, based on the total amount of the lubricating oil composition, from the viewpoint of a friction reducing effect. The mass ppm or more, more preferably 100 mass ppm or more, and particularly preferably 200 mass ppm or more. On the other hand, from the viewpoints of solubility in lubricating base oil, storage stability and oxidative stability, and economic efficiency, it is preferably 600 ppm by mass or less, more preferably 500 ppm by mass or less, and particularly preferably 300 ppm by mass or less. is there. In addition, when the content of the component (B) exceeds 600 ppm by mass, particularly when a poly α-olefin or a hydride thereof is used as a lubricating base oil, sufficient solubility cannot be obtained, and precipitation occurs during long-term storage. There is a fear. Furthermore, it is not preferable from the aspect of economy.

  In order to further improve the performance, the lubricating oil composition of the present invention may contain any additive generally used in lubricating oils depending on the purpose. Examples of such additives include metal detergents, ashless dispersants, viscosity index improvers, antiwear agents (or extreme pressure agents), antioxidants, corrosion inhibitors, rust inhibitors, demulsifiers, metals Examples thereof include additives such as an inactivating agent and an antifoaming agent.

  As metal-based detergents, normal salts or basics such as alkali metals or alkaline earth metal salicylates, alkali metals or alkaline earth metal sulfonates, alkali metals or alkaline earth metal phenates, and alkali metals or alkaline earth metal salicylates Mention may be made of salts. Examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include magnesium, calcium and barium. Magnesium or calcium is preferable, and calcium is particularly preferable.

Of these, alkali metal or alkaline earth metal salicylate detergents (hereinafter referred to as metal salicylate detergents) are preferred from the viewpoint of friction reduction.
Metallic salicylate detergents are salicylic acid obtained by adding equimolar hydrocarbon groups (for example, olefins having 8 to 30 carbon atoms) to salicylic acid, or equimolar hydrocarbon groups (for example, olefins having 8 to 30 carbon atoms) to phenol. A neutral salicylic acid metal salt obtained by allowing an equivalent metal salt or metal base or the like to act on salicylic acid having one hydrocarbon group having 8 to 30 carbon atoms, which is then carboxylated with carbon dioxide or the like, Furthermore, a basic salt obtained by heating an excess metal salt or metal base (metal hydroxide or oxide) in the presence of water to the neutral salicylic acid metal salt, the neutral salicylic acid metal salt Examples include overbased salts (superbasic salts) obtained by reacting carbon dioxide or boric acid or borates with bases such as metal hydroxides in the presence. . In addition, these (over) basification reactions are usually performed in a solvent (an aliphatic hydrocarbon solvent such as hexane, an aromatic hydrocarbon solvent such as xylene, a light lubricating oil base oil, or the like).

The olefins having 8 to 30 carbon atoms used for synthesizing salicylate are generally roughly divided into a group of olefins having 8 to 19 carbon atoms and a group of olefins having 20 to 30 carbon atoms, and each hydrocarbon group has Added salicylic acid is synthesized.
The hydrocarbon group is preferably an alkyl group derived from a polymer or copolymer such as ethylene, propylene and butylene, particularly an alkyl group derived from a linear α-olefin such as an ethylene polymer.

  In the present invention, as a metal salicylate detergent, a salicylic acid metal salt having a hydrocarbon group having 8 to 19 carbon atoms (for example, an alkyl group having 8 to 19 carbon atoms) (hereinafter sometimes referred to as “salicylic acid metal salt C-a”). Or a salicylic acid metal salt having a hydrocarbon group having 20 to 30 carbon atoms (for example, an alkyl group having 20 to 30 carbon atoms) (hereinafter also referred to as “salicylic acid metal salt Cb” in some cases) alone, Or both can be used in combination. The salicylic acid metal salt Cb is preferable from the viewpoint of friction reduction. On the other hand, from the viewpoint of synergistically improving storage stability and low-temperature fluidity, it is of course possible to use salicylic acid metal salt Ca and salicylic acid metal salt Cb in combination.

  Metal salicylate detergents are usually obtained by reaction in diluents such as solvents and lubricating base oils. The metal content of the metal salicylate detergent thus obtained is the metal salicylate detergent. Based on the total amount of the agent, the lower limit is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, further preferably 5.0% by mass or more, and particularly preferably 7.0% by mass or more. . The upper limit is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 12% by mass or less, and particularly preferably 10% or less.

  The base number of the metal salicylate detergent is preferably adjusted to a lower limit of preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, still more preferably 150 mgKOH / g or more, particularly preferably 200 mgKOH / g or more. It is desirable to use a basic salicylate detergent as the main component. The upper limit is preferably 400 mgKOH / g or less, more preferably 300 mgKOH / g or less, more preferably 250 mgKOH / g or less, and more preferably an overbased salicylate-based detergent used as a main component. The base number referred to here is 7. JIS K2501 “Petroleum products and lubricating oils-Neutralization number test method”. Means the base number measured by the perchloric acid method according to the above.

  In addition, the metal ratio of the metal salicylate detergent is not particularly limited, and usually 20 or less can be used alone or in combination. The metal ratio is preferably less than 4.5, more preferably 3 or less. The metal ratio referred to here is expressed by (valence of metal element in salicylate detergent) × (metal element content (mol%)) / (soap group content (mol%)). The term “soap group” means a salicylic acid group such as calcium and magnesium.

  When the lubricating oil composition of the present invention contains a metal salicylate detergent, the content is preferably 0.1% by mass or more, more preferably 0.5% by mass based on the total amount of the lubricating oil composition. % Or more, more preferably 1% by mass or more. Moreover, it is preferably 15% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, and particularly preferably 3% by mass or less. If the content is less than 0.1% by mass, the friction reduction effect may last only for a short period, and if it exceeds 15% by mass, the effect commensurate with the content may not be obtained. is there. Further, the lower limit of the metal amount is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, and particularly preferably 0.15% by mass or more. . The upper limit is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0.3% by mass or less. If the amount of metal is less than 0.01% by mass, the friction reduction effect may last only for a short period of time, and if it exceeds 1.5% by mass, an effect commensurate with the content cannot be obtained. There is a fear.

  Examples of the ashless dispersant include nitrogen-containing compounds having at least one linear or branched alkyl group or alkenyl group having 40 to 400 carbon atoms or derivatives thereof, or modified products of alkenyl succinimide. It is done. One type or two or more types arbitrarily selected from these can be blended.

  The carbon number of the alkyl group or alkenyl group of the ashless dispersant is preferably 40 to 400, more preferably 60 to 350. When the number of carbon atoms of the alkyl group or alkenyl group is less than 40, the solubility of the compound in the lubricating base oil tends to decrease. On the other hand, when it exceeds 400, the low-temperature fluidity of the lubricating oil composition tends to deteriorate. It is in. The alkyl group or alkenyl group may be linear or branched, but is preferably branched from an olefin oligomer such as propylene, 1-butene, isobutylene, or a co-oligomer of ethylene and propylene. Examples thereof include an alkyl group and a branched alkenyl group.

The succinimide includes a so-called monotype succinimide represented by the general formula (5) in which succinic anhydride is added to one end of the polyamine, and a general formula in which succinic anhydride is added to both ends of the polyamine ( And so-called bis-type succinimide represented by 6).

In the general formula (5), R ⁹ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably an alkyl group or alkenyl group having 60 to 350 carbon atoms, and p is 1 to 5, preferably 2 to 4. Indicates an integer.
In the general formula (6), R ¹⁰ and R ¹¹ may be the same or different and each represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably an alkyl group or alkenyl group having 60 to 350 carbon atoms, A polybutenyl group is preferred. q represents an integer of 0 to 4, preferably 1 to 3.

  The lubricating oil composition of the present invention may contain either monotype or bistype succinimide, or may contain both.

  The method for producing succinimide is not particularly limited. For example, an alkyl succinic acid or alkenyl succinic acid obtained by reacting a compound having an alkyl group or alkenyl group having 40 to 400 carbon atoms with maleic anhydride at 100 to 200 ° C. It can be obtained by reacting with a polyamine. Specific examples of the polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

In the present invention, any one selected from the succinimides and / or derivatives thereof can be used, but the weight average molecular weight is preferably 6,500 or more, more preferably 7,000 or more, More preferably, it is 8,000 or more, Especially preferably, it is 9,000 or more. When the weight average molecular weight is less than 6,500, the molecular weight of the non-polar polybutenyl group is small and the sludge dispersibility is poor, and the polar group amine portion that may become an active site for oxidative degradation is relatively large. Therefore, it is considered that the effect of prolonging the life cannot be obtained because of poor oxidation stability. On the other hand, the upper limit is not particularly limited, but is preferably 20,000 or less, and more preferably 15,000 or less, from the viewpoint of preventing deterioration of the low temperature viscosity characteristics.
In addition, the weight average molecular weight as used herein means that two columns of Tosoh GMHHR-M (7.8 mm ID × 30 cm) are used in series on a Waters 150-C ALC / GPC apparatus, and the solvent is tetrahydrofuran, It is a weight-average molecular weight in terms of polystyrene measured by a temperature of 23 ° C., a flow rate of 1 mL / min, a sample concentration of 1 mass%, a sample injection amount of 75 μL, and a detector differential refractometer (RI).

Moreover, benzylamine can also be used as an ashless dispersant. Preferable examples of benzylamine include compounds represented by the following general formula (7).

In the general formula (7), R ¹² represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably an alkyl group or alkenyl group having 60 to 350 carbon atoms, and r is 1 to 5, preferably 2 to 4. Indicates an integer.

  The method for producing benzylamine is not limited in any way. For example, after reacting polyolefin such as propylene oligomer, polybutene, and ethylene-α-olefin copolymer with phenol to form alkylphenol, formaldehyde and diethylenetriamine are added thereto. , Triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and other polyamines can be obtained by reacting by a Mannich reaction.

More specifically, examples of the polyamine include compounds represented by the following general formula (8).
^{_{R 13 -NH- (CH 2 CH 2}} NH) s -H (8)
In the general formula (8), R ¹³ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably an alkyl group or alkenyl group having 60 to 350, and s is an integer of 1 to 5, preferably 2 to 4. Indicates.

  The production method of polyamine is not limited in any way. For example, after chlorinating polyolefin such as propylene oligomer, polybutene, and ethylene-α-olefin copolymer, ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine It can be obtained by reacting polyamines such as tetraethylenepentamine and pentaethylenehexamine.

  In addition, as other derivatives, specifically, the above-mentioned nitrogen-containing compounds may have 1 to 30 carbon atoms such as monocarboxylic acids (fatty acids, etc.), oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc. 2 to 30 polycarboxylic acids, alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates (for example, ethylene carbonate), hydroxy (poly) alkylene carbonates and the like are allowed to act on the remaining amino groups and / or imino groups Examples thereof include a modified compound obtained by neutralizing a part or all of the above or an amidated organic acid, a sulfur-modified compound obtained by allowing a sulfur compound to act on the above-described nitrogen-containing compound, and the like. Moreover, the thing modified | denatured with the boron compound is also mentioned.

  However, in the lubricating oil composition of the present invention, the above-described nitrogen-based compound that is not boronated is preferred as the ashless dispersant.

  When the lubricating oil composition of the present invention contains an ashless dispersant, the content of the ashless dispersant is preferably 0.01 to 20% by mass, more preferably 0.1%, based on the total amount of the lubricating oil composition. -10 mass%. When the content of the ashless dispersant is less than 0.01% by mass, the effect of improving the friction reduction property may be insufficient. On the other hand, when the content exceeds 20% by mass, the low-temperature fluidity of the lubricating oil composition is low. There is a risk of significant deterioration.

The viscosity index improver is specifically a non-dispersed or dispersed ester group-containing viscosity index improver, for example, a non-dispersed or dispersed poly (meth) acrylate viscosity index improver, non-dispersed or dispersed Type olefin- (meth) acrylate copolymer-based viscosity index improver, styrene-maleic anhydride copolymer-based viscosity index improver, and mixtures thereof. Among these, non-dispersed or dispersed poly (meth) An acrylate viscosity index improver is preferable. A non-dispersed or dispersed polymethacrylate viscosity index improver is particularly preferable.
Other examples of the viscosity index improver include non-dispersed or dispersed ethylene-α-olefin copolymers or hydrogenated products thereof, polyisobutylene or hydrogenated products thereof, styrene-diene hydrogenated copolymers, and polyalkylstyrenes. Can be mentioned.

  As the antiwear agent (or extreme pressure agent), any antiwear agent / extreme pressure agent used for lubricating oil can be used. For example, sulfur-based, phosphorus-based, sulfur-phosphorus extreme pressure agents and the like can be used. Specifically, zinc dialkyldithiophosphate (ZnDTP), phosphites, thiophosphites, dithiophosphites Acid esters, trithiophosphites, phosphate esters, thiophosphate esters, dithiophosphate esters, trithiophosphate esters, amine salts thereof, metal salts thereof, derivatives thereof, dithiocarbamate, zinc dithio Carbamate, MoDTC, disulfides, polysulfides, sulfurized olefins, sulfurized fats and oils, and the like can be given. Among these, addition of a sulfur-based extreme pressure agent is preferable, and sulfurized fats and oils are particularly preferable.

  Examples of the antioxidant include ashless antioxidants such as phenols and amines, and metal antioxidants such as copper and molybdenum. Specifically, for example, as a phenol-based ashless antioxidant, 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert- Butylphenol) and the like are amine-based ashless antioxidants such as phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, and dialkyldiphenylamine.

  Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiadiazole, or imidazole compounds.

  Examples of the rust preventive include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester.

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

  Examples of metal deactivators include imidazoline, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis. Examples thereof include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and β- (o-carboxybenzylthio) propiononitrile.

Examples of the antifoaming agent include silicone oil having a kinematic viscosity at 25 ° C. of 1000 to 100,000 mm ² / s, alkenyl succinic acid derivative, ester of polyhydroxy aliphatic alcohol and long chain fatty acid, methyl salicylate and o- Examples thereof include hydroxybenzyl alcohol.

  When these additives are contained in the lubricating oil composition according to the present invention, the respective contents are based on the total amount of the lubricating oil composition, 0.0005 to 1% by mass for the antifoaming agent, and other additions. About an agent, it is normally chosen from the range of 0.01-10 mass%.

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

(Examples 1-8, Comparative Examples 1-5)
A lubricating oil composition according to the present invention (Examples 1 to 8) and a comparative lubricating oil composition (Comparative Examples 1 to 5) were prepared. These compositions were subjected to a friction test using a reciprocating friction tester (SRV, oil temperature: 110 ° C., load: 400 N, time: 30 min), and the results are shown in Table 1.
As is apparent from the results shown in Table 1, the lubricating oil compositions of Examples 1 to 8 are excellent in the coefficient of friction improvement ratio relative to the reference oil, and are comparative examples not containing the component (A) or (B). It turns out that it is excellent in friction reduction property with respect to the composition of 1-5.

  The lubricating oil composition of the present invention can be used in general for lubricating oils that are required to have a friction reducing effect, gear oil for automobile transmissions and final reduction gears, and also for motorcycles, automobiles, power generation, and cogeneration. It can be particularly suitably used for internal combustion engines such as gasoline engines, diesel engines, gas engines, etc., and is also useful for various engines for ships and outboard motors.

Claims (3)

The lubricating base oil contains (A) a metal salt of a phosphate ester represented by the general formula (1) and (B) an organomolybdenum compound in which the ratio of molybdenum element to sulfur element is 1: 3.5 or more. A lubricating oil composition.

(Wherein R _{1 to} R ₄ are a hydrocarbon group having 1 to 30 carbon atoms, an alkyl group or alkenyl group having 1 to 30 carbon atoms, or an alkylthioethyl group composed of an alkyl group having 1 to 30 carbon atoms, and the same X ₁ , X ₂ , X ₃ and X ₄ represent sulfur or oxygen, respectively, X ₁ and X ₂ are either oxygen or all oxygen, and X ₃ and X ₄ are either One of them is oxygen or all oxygen, and Y represents a metal element) 2. The lubricating oil composition according to claim 1, wherein R _{1 to} R ₄ in the formula (1) are each a linear alkyl group having 4 to 8 carbon atoms.   The lubricating oil composition according to claim 1, comprising an ashless dispersant containing no boron.