JP5930904B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to a novel lubricating oil composition, and relates to a lubricating oil composition having excellent NOx resistance, antioxidant properties, base number maintenance and cleanliness. In particular, the present invention relates to a lubricating oil composition suitably used as a lubricating oil for an internal combustion engine.

  Conventionally, lubricating oils and greases are used for internal combustion engines, automatic transmissions, and the like in order to make their operations 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, various additives such as antiwear agents, metallic detergents, ashless dispersants, and antioxidants are blended in conventional engine oils in order to satisfy these required performances. Since engine oil is always in contact with peroxide, which is an active species for oxidative degradation, in the piston-cylinder region, excellent oxidation resistance is required. In order to improve the oxidative stability of engine oil, it has traditionally been blended with phenolic or amine antioxidants that function as chain terminators and zinc dialkyldithiophosphates (ZDTP) that function as peroxide decomposers. Are known. It has also been conventionally known that an organic molybdenum compound is used as a peroxide decomposer. On the other hand, in order to improve the oxidative stability of lubricating oil, a hindered amine is blended (see, for example, Patent Documents 1 and 2), a phenolic antioxidant, or a zinc dialkyldithiophosphate and a hindered amine. Is also conventionally known (see, for example, Patent Documents 3 to 5). However, it is not known that a hindered amine compound, an organic molybdenum compound, and a phenolic antioxidant are blended simultaneously in order to improve NOx resistance.

JP 60-28496 A JP-A-3-45695 JP-A-3-45696 JP-A-4-309597 JP 2009-197135 A

  The present invention is an excellent combination of a conventional phenolic or amine antioxidant and zinc dialkyldithiophosphate, a phenolic or amine antioxidant, or a combination of zinc dialkyldithiophosphate and hindered amine. Provided is a lubricating oil composition having NOx properties, oxidation stability, base number maintenance properties (long drain properties) and cleanliness, particularly suitable for use as a lubricating oil for internal combustion engines.

As a result of earnest research on the above problems, the present inventor has completed the present invention.
That is, the present invention is a lubricating oil composition comprising a lubricating base oil containing (A) 2,2,6,6 tetraalkylpiperidine derivative and (B) an organomolybdenum compound.

  Further, the present invention is the above lubricating oil composition characterized by further containing (C) a hindered phenol-based antioxidant and / or an aromatic amine-based antioxidant.

［一般式（１）において、Ｘ^１、Ｘ^２、Ｘ^３及びＸ^４は、それぞれ個別に酸素原子又は硫黄原子を示し、かつこれらのうちの少なくとも２つは酸素原子であり、Ｒ^１、Ｒ^２及びＲ^３は、それぞれ個別に水素原子又は炭素数１〜３０の炭化水素基を示す。］ The present invention further comprises (D) a phosphorus compound represented by the general formula (1) and at least one compound selected from the group consisting of a metal salt or an amine salt in an amount of 0.005 in terms of phosphorus element. The lubricating oil composition described above, which contains 0.5% by mass.

[In General Formula (1), X ¹ , X ² , X ³ and X ⁴ each independently represent an oxygen atom or a sulfur atom, and at least two of these are oxygen atoms, and R ¹ , R 4 ² and R ³ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. ]

［一般式（２）および（３）において、Ｒは炭素数１〜３０のアルキル基あるいはアリール基であり、同一でも異なっていてもよい。Ｙはアルカリ金属を除く金属元素を示し、ｍおよびｎはそれぞれ個別に１〜４の整数を示す。］ In the present invention, the component (D) is a phosphoric acid ester metal salt containing no sulfur represented by the general formula (2) and / or the general formula (3). It is.

[In General Formulas (2) and (3), R is an alkyl group or an aryl group having 1 to 30 carbon atoms, which may be the same or different. Y represents a metal element excluding an alkali metal, and m and n each independently represent an integer of 1 to 4. ]

  The lubricating oil composition of the present invention has excellent NOx resistance, antioxidant properties, base number maintenance and cleanliness, and is particularly suitably used as a lubricating oil for internal combustion engines.

  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 the lubricant dewaxing process and / or synthetic wax (Fischer-Tropsch wax, GTL wax, etc.) obtained by the 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 100 or more. More preferably, it is 110 or more, More preferably, it is 120 or more. Moreover, it is preferable that it is 100 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 10 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 lubricating oil composition of the present invention contains a 2,2,6,6 tetraalkylpiperidine derivative having a substituent at the 4-position as the component (A).

  Examples of the substituent at the 4-position include a carboxylic acid residue, an alkoxy group, an alkylamino group, an amide group, and the like, and the N-position is substituted with an alkyl group having 1 to 4 carbon atoms. Also good. Specifically, the compounds represented by the following general formulas (a) to (f) can be exemplified.

In the present invention, a carboxylic acid residue is particularly preferable. As the carboxylic acid group, those having an isoalkyl group are particularly preferred. The isoalkyl group is preferably an alkyl group having 6 to 30 carbon atoms, preferably 10 or more, more preferably 16 or more. Moreover, 24 or less is preferable and 20 or less is more preferable.
When the number of carbon atoms is 5 or less, the molecular weight is too small and may evaporate at a high temperature. When the number of carbon atoms exceeds 30, the low-temperature viscosity characteristics of the composition deteriorate, which is not preferable.

In the general formulas (a) to (f), R ¹ represents a methyl group, R ² represents hydrogen or an alkyl group having 1 to 4 carbon atoms, R ³ and R ⁴ represent an oil-soluble group having 4 or more carbon atoms, m , N, o, p and q each independently represent an integer of 1 to 30.

  In the lubricating oil composition of the present invention, the lower limit of the content of the component (A) is 0.005% by mass or more, preferably 0.01% by mass or more, in terms of nitrogen element, based on the total amount of the composition. Especially preferably, it is 0.02 mass% or more. On the other hand, the upper limit of the content of the component (A) is 0.2% by mass or less, preferably 0.1% by mass or less, in terms of nitrogen element, based on the total amount of the composition. When the content of the component (A) is less than 0.005% by mass, the high temperature cleanability maintenance performance is poor. On the other hand, when the content of the component (A) exceeds 0.2% by mass, the high-temperature cleaning performance may be rather deteriorated due to the generation of sludge due to oxidative degradation.

The lubricating oil composition of the present invention contains an organic molybdenum compound as component (B).
Examples of the organic molybdenum compound used in the present invention include various organic molybdenum compounds such as an organic molybdenum compound containing sulfur or an organic molybdenum compound containing no sulfur as a constituent element.

First, examples of the organic molybdenum compound containing sulfur include molybdenum dithiophosphate and molybdenum dithiocarbamate.
As molybdenum dithiophosphate, the compound represented by following General formula (4) is mentioned, for example.

In the general formula (4), R ¹ , R ² , R ³ and R 4 may be the same or different, and have 2 to 30 carbon atoms, preferably 5 to 18 carbon atoms, more preferably 5 to 5 carbon atoms. 12 represents a hydrocarbon group such as an alkyl group having 12 carbon atoms or a (alkyl) aryl group having 6 to 18 carbon atoms, preferably 10 to 15 carbon atoms. Y ¹ , Y ² , Y ³ and Y ⁴ each independently represent a sulfur atom or an oxygen atom.

  As the molybdenum dithiocarbamate, specifically, a compound represented by the following general formula (5) can be used.

In the general formula (5), R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each has 2 to 24 carbon atoms, preferably 4 to 13 carbon atoms, or carbon atoms. A hydrocarbon group such as an (alkyl) aryl group having 6 to 24, preferably 10 to 15 carbon atoms is shown. Y ⁵ , Y ⁶ , Y ⁷ and Y ⁸ each independently represent a sulfur atom or an oxygen atom.

  In addition, organic molybdenum compounds containing sulfur other than these include molybdenum compounds (for example, molybdenum oxide such as molybdenum dioxide and molybdenum trioxide, orthomolybdic acid, paramolybdic acid, molybdic acid such as (poly) sulfurized molybdic acid, These metal salts of molybdate, molybdenum salts such as ammonium salts, molybdenum sulfides such as molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, and polysulfide molybdenum, molybdenum sulfides, metal salts or amine salts of molybdenum sulfides, chlorides Molybdenum halides such as molybdenum) and sulfur-containing organic compounds (eg, alkyl (thio) xanthates, thiadiazoles, mercaptothiadiazoles, thiocarbonates, tetrahydrocarbylthiuram disulfides, bis (di (thio) hydrocarbons). Bildithiophosphonate) disulfide, organic (poly) sulfide, sulfurized ester, etc.) or complexes with other organic compounds, or sulfur-containing molybdenum compounds such as molybdenum sulfide and sulfurized molybdic acid, and sulfur as a constituent element to be described later Amine compounds, succinimides, organic acids, complexes with alcohols, etc., or elemental sulfur, hydrogen sulfide, phosphorus pentasulfide, sulfur oxide, inorganic sulfide, hydrocarbyl (poly ) Constituent elements described in the section of sulfur sources such as sulfide, sulfurized olefin, sulfurized ester, sulfurized wax, sulfurized carboxylic acid, sulfurized alkylphenol, thioacetamide, thiourea, and organic molybdenum compounds that do not contain sulfur As sulfur-free molybdenum A sulfur-containing organic molybdenum obtained by reacting a compound with an organic compound not containing sulfur, such as an amine compound, a succinimide, an organic acid, or an alcohol, described in the section of an organic molybdenum compound containing no sulfur as a constituent element described later Various compounds such as compounds can be mentioned. Specifically, organic molybdenum compounds such as those described in JP-A-56-10591 and US Pat. No. 4,263,152 can be exemplified.

As the organic molybdenum compound, an organic molybdenum compound containing no sulfur as a constituent element can be used.
Specific examples of organic molybdenum compounds that do not contain sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, and molybdenum salts of alcohols. Complexes, molybdenum salts of organic acids and molybdenum salts of alcohols are preferred.

The molybdenum - The molybdenum compounds constituting the amine complex, molybdenum trioxide or its hydrate _{(MoO 3 · nH 2 O)} , molybdic acid _(H 2 _MoO 4), molybdenum acid alkali metal salts _(M 2 _MoO 4; M represents an alkali metal), ammonium molybdate ((NH ₄ ) ₂ MoO ₄ or (NH ₄ ) ₆ [Mo ₇ O ₂₄ ] · 4H ₂ O), MoCl ₅ , MoOCl ₄ , MoO ₂ Cl ₂ , MoO ₂ Examples thereof include molybdenum compounds containing no sulfur such as Br ₂ and Mo ₂ O ₃ Cl ₆ . Among these molybdenum compounds, hexavalent molybdenum compounds are preferable from the viewpoint of the yield of the molybdenum-amine complex. Further, from the viewpoint of availability, among the hexavalent molybdenum compounds, molybdenum trioxide or a hydrate thereof, molybdic acid, alkali metal molybdate, and ammonium molybdate are preferable.

  In addition, the amine compound constituting the molybdenum-amine complex is not particularly limited, but as the nitrogen compound, a monoamine, diamine, polyamine having a C8-20 alkyl group or alkenyl group or a heterocyclic ring such as imidazoline. Examples thereof include compounds; alkylene oxide adducts of these compounds; and mixtures thereof. Of these amine compounds, primary amines, secondary amines and alkanolamines are preferred.

  Carbon number of the hydrocarbon group which the amine compound which comprises a molybdenum-amine complex has becomes like this. Preferably it is 4 or more, More preferably, it is 4-30, Most preferably, it is 8-18. When the number of carbon atoms of the hydrocarbon group of the amine compound is less than 4, the solubility tends to deteriorate. Moreover, by setting the number of carbon atoms of the amine compound to 30 or less, the molybdenum content in the molybdenum-amine complex can be relatively increased, and the effects of the present invention can be further enhanced with a small amount of compounding.

  The molybdenum-succinimide complex is a complex of a sulfur-free molybdenum compound as exemplified in the description of the molybdenum-amine complex and a succinimide having an alkyl group or alkenyl group having 4 or more carbon atoms. Is mentioned. As the succinimide, a succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms or an alkenyl group in the molecule described in the ashless dispersant, or a carbon number of 4 to 39, preferably carbon number. Examples thereof include succinimide having 8 to 18 alkyl groups or alkenyl groups. If the alkyl group or alkenyl group in the succinimide has less than 4 carbon atoms, the solubility tends to deteriorate. A succinimide having an alkyl group or an alkenyl group having more than 30 carbon atoms and not more than 400 carbon atoms can also be used. By setting the alkyl group or alkenyl group to 30 or less carbon atoms, molybdenum-succinimide is obtained. The molybdenum content in the complex can be relatively increased, and the effects of the present invention can be further enhanced with a small amount of compounding.

  Examples of the molybdenum salt of an organic acid include salts of molybdenum bases such as molybdenum oxide or molybdenum hydroxide, molybdenum carbonate or molybdenum chloride exemplified in the description of the molybdenum-amine complex with an organic acid. It is done. As the organic acid, phosphorus-containing acid and carboxylic acid are preferable.

  Moreover, as carboxylic acid which comprises the molybdenum salt of carboxylic acid, either a monobasic acid or a polybasic acid may be sufficient.

  As the monobasic acid, a fatty acid having usually 2 to 30, preferably 4 to 24, more preferably 4 to 12 carbon atoms is used. The fatty acid may be linear or branched, and saturated. However, it may be unsaturated.

  Moreover, as a monobasic acid, in addition to the above fatty acid, a monocyclic or polycyclic carboxylic acid (which may have a hydroxyl group) may be used, and the carbon number thereof is preferably 4 to 30, and more preferably. Is 7-30. The monocyclic or polycyclic carboxylic acid is an aromatic carboxylic acid having 0 to 3, preferably 1 to 2 linear or branched alkyl groups having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms. Or cycloalkyl carboxylic acid etc. are mentioned, More specifically, (alkyl) benzene carboxylic acid, (alkyl) naphthalene carboxylic acid, (alkyl) cycloalkyl carboxylic acid, etc. can be illustrated. Preferable examples of the monocyclic or polycyclic carboxylic acid include benzoic acid, salicylic acid, alkylbenzoic acid, alkylsalicylic acid, and cyclohexanecarboxylic acid.

  Examples of polybasic acids include dibasic acids, tribasic acids, and tetrabasic acids. The polybasic acid may be a chain polybasic acid or a cyclic polybasic acid. Further, in the case of a chain polybasic acid, it may be either linear or branched, and may be either saturated or unsaturated. As the chain polybasic acid, a chain dibasic acid having 2 to 16 carbon atoms is preferable.

  Examples of the molybdenum salt of alcohol include a salt of a molybdenum compound not containing sulfur as exemplified in the description of the molybdenum-amine complex and an alcohol. The alcohol is a monohydric alcohol, polyhydric alcohol, polyhydric alcohol. Any of a partial ester or partial ether compound of alcohol, a nitrogen compound having a hydroxyl group (alkanolamine, etc.), etc. may be used. Molybdic acid is a strong acid and forms an ester by reaction with alcohol. The ester of molybdic acid and alcohol is also included in the molybdenum salt of alcohol in the present invention.

As the monohydric alcohol, those having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms are usually used. Such alcohols may be linear or branched, and saturated. Or may be unsaturated.
Moreover, as a polyhydric alcohol, the thing of 2-10 valence is preferable, Preferably it is 2-6 valence.

  Examples of the partial ester of the polyhydric alcohol include compounds in which a part of the hydroxyl group of the polyhydric alcohol exemplified in the description of the polyhydric alcohol has been hydrocarbyl esterified, among which glycerin monooleate and glycerin dioleate. Sorbitan monooleate, sorbitandiolate, pentaerythritol monooleate, polyethylene glycol monooleate, polyglycerin monooleate and the like are preferable.

  Moreover, as the partial ether of the polyhydric alcohol, an ether bond is formed by condensation of polyhydric alcohols, a compound in which a part of the hydroxyl groups of the polyhydric alcohol exemplified in the description of the polyhydric alcohol is hydrocarbyl etherified. Compounds (such as sorbitan condensate) and the like, among which 3-octadecyloxy-1,2-propanediol, 3-octadecenyloxy-1,2-propanediol, polyethylene glycol alkyl ether and the like are preferable.

  Examples of the nitrogen compound having a hydroxyl group include alkanolamines exemplified in the description of the molybdenum-amine complex, and alkanolamides (diethanolamide, etc.) in which the amino group of the alkanol is amidated. Among them, stearyldiethanolamine Polyethylene glycol stearylamine, polyethylene glycol dioleylamine, hydroxyethyl laurylamine, oleic acid diethanolamide and the like are preferable.

  As the sulfur-containing organomolybdenum compound in the present invention, molybdenum dithiocarbamate and molybdenum dithiophosphate are preferable because they are excellent in friction reduction effect, and they are excellent in the effect of improving the antioxidant property and further reduce the deposits in the top ring groove of the diesel engine. In view of the above, the above-mentioned sulfur source, a reaction product of a molybdenum compound that does not contain sulfur as a constituent element, and an organic compound (such as succinimide) that does not contain sulfur, or a sulfur that contains sulfur as a constituent element. It is desirable to use organic molybdenum compounds that do not.

  In the composition of the present invention, the content of the organic molybdenum compound as the component (B) is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0.001% by mass or more in terms of molybdenum element based on the total amount of the composition. 005 mass% or more, more preferably 0.01 mass% or more, preferably 0.2 mass% or less, more preferably 0.1 mass% or less, still more preferably 0.05 mass% or less, particularly preferably. Is 0.02 mass% or less. When the content is less than 0.001% by mass, the thermal and oxidation stability of the lubricating oil composition becomes insufficient, and in particular, it tends to be impossible to maintain excellent cleanliness over a long period of time. On the other hand, when the content exceeds 0.2% by mass, an effect commensurate with the content cannot be obtained, and the storage stability of the lubricating oil composition tends to decrease.

  The lubricating oil composition of the present invention preferably contains a hindered phenol antioxidant and / or an aromatic amine antioxidant as component (C). By containing such component (C), it is extremely effective for improving oxidation stability together with the presence of (A) 2,2,6,6 tetraalkylpiperidine derivative and (B) organomolybdenum compound.

  Specific examples of the hindered phenol-based antioxidant include 4,4′-methylenebis (2,6-di-tert-butylphenol) and 4,4′-bis (2,6-di-tert- Butylphenol), 4,4′-bis (2-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-) 6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6-di-tert-butylphenol), 2,2′- Methylenebis (4-methyl-6-nonylphenol), 2,2′-isobutylidenebis (4,6-dimethylphenol), 2,2′-me Renbis (4-methyl-6-cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6 tert-Butylphenol, 2,6-di-tert-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4 (N, N′-dimethylaminomethylphenol), 4,4′-thiobis (2-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), 2,2′-thiobis (4-methyl-6-tert-butylphenol), bis ( 3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxy) Cybenzyl) sulfide, 2,2′-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octyl-3- (3,5-di-tert-butyl- 4-hydroxyphenyl) propionate, tridecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4- Hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and mixtures thereof. Of these, phenolic compounds having a molecular weight of 240 or more are more preferably used because of their high decomposition temperature and their antioxidant effect even under higher temperature conditions.

  When the hindered phenol-based antioxidant is contained, the content is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 0.4% by mass or more based on the total amount of the composition. It is. On the other hand, the upper limit is preferably 3% by mass or less, more preferably 2% by mass or less, and particularly preferably 1.0% by mass or less. When the content of the composition of the present invention is 0.1% by mass or more, the composition of the present invention can easily maintain excellent cleanliness over a long period. On the other hand, when the content exceeds 3% by mass, the composition is stored. Since stability deteriorates, it is not preferable.

  Specific examples of the aromatic amine antioxidant include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, dialkyldiphenylamine, N, N′-diphenyl-p-phenylenediamine, and mixtures thereof. Here, examples of the alkyl group include linear or branched alkyl groups having 1 to 20 carbon atoms.

  The content in the case of containing an aromatic amine-based antioxidant is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.4% by mass or more, based on the total amount of the composition. It is. On the other hand, the upper limit is preferably 5% by mass or less, more preferably 2.5% by mass or less, and particularly preferably 2.0% by mass or less. When the content of the composition of the present invention is 0.1% by mass or more, the composition of the present invention can easily maintain excellent cleanliness over a long period. On the other hand, when the content exceeds 5% by mass, the composition is stored. Since stability deteriorates, it is not preferable.

  As the component (C) of the lubricating oil composition of the present invention, a hindered phenol antioxidant is more preferable.

  The lubricating oil composition of the present invention contains at least one compound (phosphorus-containing antiwear agent) selected from the group consisting of phosphorus compounds represented by general formula (1) and their metal salts as component (D). It is preferable to do.

In the general formula (1), X ¹ , X ² , X ³ and X ⁴ each independently represent an oxygen atom or a sulfur atom. And at least two of these are oxygen atoms. R ¹ , R ² and R ³ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms.

Specific examples of the hydrocarbon group having 1 to 30 carbon atoms represented by R ^{1 to} R ³ include an alkyl group, a cycloalkyl group, an alkenyl group, an alkyl-substituted cycloalkyl group, an aryl group, and an alkyl-substituted aryl group. And arylalkyl groups.
^R 1 above hydrocarbon group having 1 to 30 carbon atoms represented by the to R ^3, 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, more preferably an alkyl group having 4 to 12 carbon atoms.

As a phosphorus compound represented by General formula (1), the following phosphorus compounds can be mentioned, for example.
Phosphoric acid, monothiophosphoric acid; phosphoric acid monoester having one hydrocarbon group having 1 to 30 carbon atoms, monothiophosphoric acid monoester; phosphoric acid diester having two hydrocarbon groups having 1 to 30 carbon atoms, monothiophosphoric acid Acid diesters; phosphoric acid triesters having three hydrocarbon groups having 1 to 30 carbon atoms, monothiophosphoric acid triesters; and mixtures thereof.

  As a salt of the phosphorus compound represented by the general formula (1), a metal base such as a metal oxide, a metal hydroxide, a metal carbonate, or a metal chloride is allowed to act on the phosphorus compound, so The salt which neutralized a part or all can be mentioned.

  Specific examples of the metal in the metal base include alkaline earth metals such as calcium, magnesium and barium, and heavy metals such as zinc, copper, iron, lead, nickel, silver, manganese and tungsten. Among these, alkaline earth metals such as calcium and magnesium and zinc are preferable. Zinc is particularly preferable.

  As the phosphorus compound salt represented by the general formula (1), zinc alkyldithiophosphate is particularly preferable, and secondary alkyldithiophosphate zinc is preferable. The alkyl group preferably has 3 to 6 carbon atoms.

Among these components (D), a salt of phosphorous acid diester having two alkyl groups or aryl groups having 3 to 18 carbon atoms and zinc or calcium, an alkyl group or aryl group having 3 to 18 carbon atoms, preferably Is a phosphorous acid triester having 3 alkyl groups having 6 to 12 carbon atoms, a salt of monoester of phosphoric acid having 1 alkyl group or aryl group having 3 to 18 carbon atoms and zinc or calcium, 3 carbon atoms A salt of a diester of phosphoric acid having 2 to 18 alkyl groups or aryl groups and zinc or calcium, or an alkyl group or aryl group having 3 to 18 carbon atoms, preferably 3 alkyl groups having 6 to 12 carbon atoms It is preferably a phosphoric acid triester.
One type or two or more types of these components (D) can be arbitrarily blended.

In the present invention, the metal salt of the general formula (1) is preferable, and it is preferable that all Xs are oxygen atoms. The metal salt of this compound is preferably a metal salt excluding alkali metals.
In this case, the structure differs depending on the valence of the metal and the number of OH groups of the phosphorus compound, and the structures of general formula (2) and general formula (3) are preferable. A metal salt of zinc is particularly preferable.

  In general formula (2) and (3), R is a C1-C30 alkyl group or an aryl group, and may be same or different. Y represents a metal element excluding an alkali metal, and m and n each independently represents an integer of 1 to 4.

  In the lubricating oil composition of the present invention, the content of the component (D) is 0.005% by mass or more, preferably 0.01% by mass or more, particularly preferably 0. On the other hand, the content thereof is 0.5% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and further preferably 0.08%. It is below mass%. 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, when used for an internal combustion engine, Since there is a concern about the adverse effect of phosphorus on the exhaust gas aftertreatment device, it is not preferable for each. When the content of the component (A) is 0.08% by mass or less, particularly 0.05% by mass or less as the phosphorus element, the influence on the exhaust gas aftertreatment device can be significantly reduced, which is particularly preferable.

The lubricating oil composition of the present invention preferably contains a metal detergent having a metal ratio of 3 or less as the component (E).
The metal ratio here is the valence of metal element × metal element content (mol) / soap group (content (mol). That is, the metal ratio is an alkali metal or alkaline earth metal detergent. The alkali metal or alkaline earth metal content with respect to the alkylsalicylic acid group, alkylphenol group, and alkylsulfonic acid group content is shown.

  Examples of metal detergents include alkali metal sulfonates or alkaline earth metal sulfonates, alkali metal phenates or alkaline earth metal phenates, and alkali metal salicylates or alkaline earth metal salicylates, alkali metal carboxylates or alkaline earth metal carboxylates. Rate and the like. In the present invention, one or more alkali metal or alkaline earth metal detergents selected from the group consisting of these, particularly alkaline earth metal detergents can be preferably used.

As an alkali metal or alkaline earth metal sulfonate, an alkali metal or alkaline earth metal salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a molecular weight of 300 to 1500, preferably 400 to 700, In particular, a magnesium salt and / or a calcium salt can be mentioned, and a calcium salt is preferably used.
Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid.

  Examples of the alkali metal or alkaline earth metal phenate include alkylphenols, alkylphenol sulfides, alkali metal or alkaline earth metal salts of Mannich reaction products of alkylphenols, particularly magnesium salts and calcium salts.

  Examples of the alkali metal or alkaline earth metal salicylate include alkali metal or alkaline earth metal salts of allyl salicylic acid, particularly magnesium salts and calcium salts. Specific examples include compounds represented by the following general formula (6).

In the general formula (6), R ¹ and R ² may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 40 carbon atoms, and the hydrocarbon group may contain oxygen or nitrogen. good. However, it is not hydrogen at the same time. M represents an alkali metal or alkaline earth metal, preferably calcium or magnesium, and n represents 1 or 2 depending on the valence of the metal.

Metal-based detergents are usually commercially available in a state diluted with a light lubricating base oil or the like, and are available, but generally the metal content is 1.0 to 20% by mass, preferably Is preferably 2.0 to 16% by mass.
The total base number of the alkaline earth metal detergent used in the present invention is arbitrary, but usually 0 to 500 mgKOH / g, preferably 60 to 230 mgKOH / g, more preferably 60 to 190 mgKOH / g. Is desirable.
The total base number referred to here is JIS K2501 “Petroleum products and lubricating oils—Test method for neutralization number”. It means the total base number measured by the perchloric acid method based on

  In the present invention, the metal ratio of the metallic detergent as the component (E) is preferably 3 or less. The metal ratio is preferably 2.6 or less, more preferably 2 or less, and particularly preferably 1.5 or less. In the present invention, when the metal ratio is 3 or less, the above-mentioned various metal detergents can be preferably used. However, since it is easy to suppress deterioration of wear prevention and increase in acid value, It is preferable to use metal sulfonates and / or alkaline earth metal phenates, and it is particularly preferable to use alkaline earth metal sulfonates. (E) By making a component into such a structure, the improvement effect of base number maintenance property, high temperature detergency, and also low friction property can be heightened more.

In the present invention, in addition to the component (E), the metal ratio exceeds 3, preferably 5 or more, more preferably 8 or more, preferably 40 or less, more preferably 20 or less, still more preferably 15 or less. An agent can be further contained. As the metal detergent having a metal ratio of more than 3 in the present invention, the above-mentioned various metal detergents can be suitably used, but it is easy to suppress deterioration of wear prevention and increase in acid value. It is preferred to use alkaline earth metal sulfonates and / or alkaline earth metal phenates, and it is desirable to use alkaline earth metal sulfonates. In particular, when an alkaline earth metal salicylate is used as the component (E), it is storage stability to use an alkaline earth metal sulfonate and / or an alkaline earth metal phenate as a metal-based detergent having a metal ratio exceeding 3. It is also desirable because of its superiority.
The blending ratio of the metal detergent with a metal ratio exceeding 3 is 10 to 10. The metal detergent with a metal ratio exceeding 3: the metal detergent with a metal ratio of 3 or less is 10 to 10 as the total amount of metal resulting from the metal detergent. 90 mass%: 90-10 mass% is preferable, More preferably, it is 40-85 mass%: 60-15 mass%, More preferably, it is 50-80 mass%: 50-20 mass%.

  The total content of the metal detergent in the present invention is preferably 0.01 to 0.2% by mass, more preferably 0, in terms of alkali metal or alkaline earth metal element, based on the total amount of the composition. 0.05 to 0.16% by mass, and more preferably 0.08 to 0.12% by mass. When the content of the metallic detergent is less than 0.01% by mass, the excellent base number maintaining ability and the high temperature cleanability as in the present invention cannot be exhibited, while the content of the metallic detergent is 0.2. When it exceeds mass%, the amount of sulfated ash in the composition cannot be within the specified range of the present application.

The lubricating oil composition of the present invention preferably contains an ashless dispersant as the component (F).
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 mono-type succinimide in which succinic anhydride is added to one end of the polyamine, and a so-called bis-type succinimide in which succinic anhydride is added to both ends of the polyamine.
The lubricating oil composition of the present invention may contain either monotype or bistype succinimide, or may contain both.

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 ¹ 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 2 -NH- (CH 2 CH 2}} NH) s -H (8)
In the general formula (8), R ² 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.

  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.

  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.

  In order to further improve the performance of the lubricating oil composition of the present invention or to give the necessary performance, a viscosity index improver, an antiwear agent (or extreme pressure agent), corrosion, as necessary. You may mix | blend various additives, such as an inhibitor, a rust inhibitor, a demulsifier, a metal deactivator, and an antifoamer, individually or in combination.

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.

The weight average molecular weight (M _w ) of the viscosity index improver is preferably 600,000 or less, more preferably 500,000 or less, and further preferably 450,000 or less. Moreover, it is preferable that it is 100,000 or more, More preferably, it is 20,000 or more, More preferably, it is 250,000 or more. When the weight average molecular weight is less than 100,000, the effect of improving the viscosity index when dissolved in a lubricating base oil is small, and the fuel economy and low temperature viscosity characteristics are inferior, and the cost may increase. In addition, when the weight average molecular weight exceeds 600,000, the viscosity increasing effect becomes too great, and not only the fuel saving property and low temperature viscosity property are inferior, but also shear stability, solubility in lubricating base oil, and storage. Stability deteriorates.

  The PSSI (Permanent Siability Index) of the viscosity index improver is preferably 70 or less, more preferably 60 or less. When PSSI exceeds 70, the shear stability deteriorates, so that it is necessary to increase the initial kinematic viscosity, which may deteriorate the fuel economy. Further, when PSSI is less than 10, the effect of improving the viscosity index when dissolved in a lubricating base oil is small, and not only is fuel efficiency and low-temperature viscosity characteristics inferior, but costs may increase. Is preferably 10 or more.

  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, phosphites, thiophosphites, dithiophosphites, trithiophosphites Esters, phosphate esters, thiophosphate esters, dithiophosphate esters, trithiophosphate esters, amine salts thereof, metal salts thereof, derivatives thereof, dithiocarbamates, zinc dithiocarbamates, disulfides, polysulfides , Sulfurized olefins, sulfurized fats and oils and the like. Among these, addition of a sulfur-based extreme pressure agent is preferable, and sulfurized fats and oils are particularly preferable.

  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 1-9, Comparative Examples 1-5)
Lubricating oil compositions according to the present invention (Examples 1 to 9) and comparative lubricating oil compositions (Comparative Examples 1 to 5) were prepared. These compositions were subjected to a NOx blowing test. As test conditions, an oxygen flow rate: 115 ml / min and NO diluted with nitrogen (NO concentration: 800 ppm) and a flow rate of 20 ml / min were mixed and introduced into 150 g of a sample having an oil temperature of 140 ° C. The test time is shown in Table 1 together with the results.
As is clear from the results shown in Table 1, the lubricating oil compositions of Examples 1 to 9 are NOx resistant to the compositions of Comparative Examples 1 to 5 that do not contain the component (A) or the component (B). It turns out that it is excellent in property.
The chemical structural formulas of HALS1, HALS2 and HALS3 described in Table 1 are shown below.

  The lubricating oil composition of the present invention can be used in general for lubricating oils that require oxidation stability and cleanliness, gear oil for automobiles and gears for final reduction gears, and also for motorcycles, automobiles, power generation, It can be particularly suitably used for internal combustion engines such as gasoline engines for cogeneration, diesel engines, gas engines, etc., and is also useful for various engines for ships and outboard motors.

Claims (4)

A lubricating oil composition comprising: (A) a 2,2,6,6 tetraalkylpiperidine derivative selected from HALS1, HALS2 and HALS3 shown below and (B) an organomolybdenum compound in the lubricating base oil. object.

  The lubricating oil composition according to claim 1, further comprising (C) a hindered phenol-based antioxidant and / or an aromatic amine-based antioxidant. Further, (D) at least one compound selected from the group consisting of the phosphorus compound represented by the general formula (1) and the metal salt or amine salt thereof is 0.005 to 0.5% by mass in terms of phosphorus element. The lubricating oil composition according to claim 1, wherein the lubricating oil composition is contained.

[In General Formula (1), X ¹ , X ² , X ³ and X ⁴ each independently represent an oxygen atom or a sulfur atom, and at least two of these are oxygen atoms, and R ¹ , R 4 ² and R ³ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. ] The lubricating oil composition according to claim 3, wherein the component (D) is a phosphoric acid ester metal salt not containing sulfur represented by the general formula (2) and / or the general formula (3).

[In General Formulas (2) and (3), R is an alkyl group or an aryl group having 1 to 30 carbon atoms, which may be the same or different. Y represents a metal element excluding an alkali metal, and m and n each independently represent an integer of 1 to 4. ]