JP6797633B2 - Lubricating oil composition for automatic transmission - Google Patents

Description

The present invention relates to a lubricating oil composition for an automatic transmission (automatic transmission oil composition), and more specifically, a gear oil composition with improved fuel efficiency, which is suitable for an automatic transmission having a synchronization mechanism such as a dual clutch transmission. Regarding things.

One of the energy saving means in gear devices such as transmissions and final reduction gears is to reduce the viscosity of lubricating oil. For example, transmissions and final reduction gears have gear bearing mechanisms, and by reducing the viscosity of the lubricating oil used for these, the stirring resistance and drag torque caused by the viscous resistance of the lubricating oil are reduced. It is considered that the power transmission efficiency is improved, and as a result, the fuel saving performance can be improved.

Japanese Unexamined Patent Publication No. 2010-196063 JP-A-2007-131856

However, when the viscosity of the lubricating oil used in these gear devices is reduced, it becomes difficult to maintain the oil film thickness on the lubricating surface, so that the seizure resistance (load bearing capacity) and wear resistance tend to decrease. ..

Furthermore, the lubricating oil used in automatic transmissions with a synchro mechanism such as dual clutch transmissions, which has been under development in recent years, has not only the performance conventionally required for automatic transmission oils, such as prevention of judder of wet clutches. , Performance that was conventionally required only for manual transmission oil, such as synchronization performance of the synchronizer ring, is also required.

The present invention is for an automatic transmission having a synchro mechanism, which satisfies the seizure resistance and wear resistance required for a transmission oil, the judder prevention property of a wet clutch, and the synchronization performance of the synchro mechanism while improving fuel efficiency. An object of the present invention is to provide a lubricating oil composition.

In one embodiment of the present invention, as (A) a lubricating oil base oil, one or more mineral oil-based base oils or one or more synthetic base oils or a mixture thereof, and (B) a thiasiazol compound are used as lubricating oils. A phosphorus-containing friction modifier having a total sulfur content of 0.20% by mass or more based on the total amount of the lubricating oil composition and (C) a linear alkyl or alkenyl group having 12 or more carbon atoms in the composition. 0.1% by mass or more based on the total amount of the lubricating oil composition, (D) phosphorus-containing additives other than the above component (C), and the total phosphorus content in the lubricating oil composition is 0. It contains (E) a poly (meth) acrylate having a weight average molecular weight of 50,000 or less, an amount of 04% by mass or more, a kinematic viscosity of the lubricating oil composition at 40 ° C. of 25 mm ² / s or less, and a viscosity index. It is a lubricating oil composition for an automatic transmission having a synchronization mechanism, which is 170 or more.

As used herein, the term "(meth) acrylate" means "acrylate and / or methacrylate".

In one preferred embodiment, the kinematic viscosity of the lubricating oil base oil (A) at 100 ° C. is 3.3 mm ² / s or less.

In one preferred embodiment, the (A) lubricating oil base oil is (A1) API classification group III base oil and / or group IV base oil in an amount of 70% by mass or more and 99% by mass or less based on the total amount of lubricating oil base oil. Including.

In one preferred embodiment, the (A) lubricating oil base oil has (A2) a kinematic viscosity at 100 ° C. of 3 mm ² / s or less, a viscosity index of 130 or more, a flammable point of 200 ° C. or more, and a pour point of −30 ° C. or less. The ester base oil is contained in an amount of 1% by mass or more and 30% by mass or less based on the total amount of the lubricating oil base oil.

In one preferred embodiment, the ratio S / P of the total sulfur content S in the lubricating oil composition to the total phosphorus content P in the lubricating oil composition is 3 or more and 8 or less.

In one preferred embodiment, the lubricating oil composition contains (F) a calcium-based cleaning agent in an amount such that the total calcium content in the lubricating oil composition is 0.01% by mass or less based on the total amount of the lubricating oil composition. ..

In one preferred embodiment, the lubricating oil composition comprises (G) an aliphatic amide compound having a linear alkyl or alkenyl group having 12 or more carbon atoms in an amount of 0.3% by mass or more based on the total amount of the lubricating oil composition. Contains 0.0% by mass or less.

According to the present invention, an automatic transmission having a synchro mechanism that satisfies the seizure resistance and wear resistance required for a transmission oil, the judder prevention property of a wet clutch, and the synchronization performance of the synchro mechanism while improving fuel efficiency. A machine lubricating oil composition can be provided.

Hereinafter, the present invention will be described in detail. Unless otherwise specified, the notation "A to B" for the numerical values A and B means "A or more and B or less". When a unit is attached only to the numerical value B in such a notation, the unit shall be applied to the numerical value A as well. The words "or" and "or" shall mean OR unless otherwise specified.

<(A) Lubricating oil base oil>
In the lubricating oil composition for an automatic transmission having the synchronization mechanism of the present invention (hereinafter, may be referred to as "automatic transmission oil" or "lubricating oil composition"), the lubricating oil base oil includes mineral oil-based base oil and A base oil consisting of one or more selected from synthetic base oils can be used without particular limitation.

Specifically, as the mineral oil-based base oil, solvent is removed, solvent extraction, and hydrogenation are performed on the lubricating oil distillate obtained by vacuum distillation of the atmospheric residual oil obtained by atmospheric distillation of crude oil. Paraffin-based or naphthen-based mineral oil-based base oils, wax-isomerized mineral oils, and GTL obtained by performing one or more refining treatments such as decomposition, hydroisomerization, solvent dewaxing, catalytic dewaxing, and hydrorefining. Examples thereof include base oil produced by a method of isomerizing WAX (gasto liquid wax).

The mineral oil-based base oil is a wax isomerization obtained by isomerizing a hydrocracked mineral oil-based base oil and / or a raw material containing 50% by mass or more of petroleum-based wax or GTL wax (for example, Fischer-Tropsch synthetic oil). Isoparaffin-based base oil can be preferably used.

Examples of the synthetic base oil include polyα-olefin (for example, ethylene-propylene copolymer, polybutene, 1-octene oligomer, 1-decene oligomer, etc.) or a hydride thereof; monoester (for example, butyl stearate, octyl). Laurate, etc.); Diesters (eg, ditridecylglutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sepate, etc.); Polyester (eg, trimellitic acid ester, etc.); Polyester Esters (eg, trimethylolpropane caprilate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, etc.); Aromatic synthetic oils (eg, alkylbenzene, alkylnaphthalene, aromatic esters, etc.). ); And a mixture thereof and the like can be exemplified.

% _{C P} of the mineral base oil is preferably 70 or more, more preferably 80 or more, and usually 99 or less, preferably 95 or less. By% C _P of the mineral base oil is less than the above lower limit, the viscosity - it is possible to improve temperature characteristics, thermal and oxidation stability and frictional properties. Further, by% C _p value of the lubricating base oil is more than the above upper limit, it is possible to increase the solubility of additives.

The% _{C A} of mineral base oil, preferably 2 or less, more preferably 1 or less, more preferably 0.8 or less, particularly preferably 0.5 or less. By% C _A of the mineral base oil is more than the above upper limit, the viscosity - it is possible to increase the temperature characteristics, thermal and oxidation stability and fuel efficiency.

% C _N of the mineral base oil is preferably 30 or less, more preferably 25 or less, and preferably 1 or more, more preferably 4 or more. By% C _N of the mineral base oil is more than the above upper limit, the viscosity - it is possible to increase the temperature characteristics, thermal and oxidation stability and frictional properties. Further, when% _CN is at least the above lower limit value, the solubility of the additive can be enhanced.

_In% C P herein,% _C A _N and% _{C A,} obtained by a method in accordance with ASTM D 3238-85, respectively (n-d-M ring analysis), percentage of total number of carbon atoms of the paraffin carbon number , Percentage of naphthen carbon number to total carbon number, and percentage of aromatic carbon number to total carbon number. That is, the above-described% C _P,% preferred range of C _N and% C _A are based on values determined by these methods, even mineral base oil, for example do not contain naphthene, determined by the above is% _{C N} may indicate a value greater than 0.

The kinematic viscosity of the lubricating oil base oil at 100 ° C. is preferably 3.3 mm ² / s or less, preferably 2.0 mm ² / s or more, more preferably 2.5 mm ² / s or more, and particularly preferably 2 It is 6 mm ² / s or more. When the kinematic viscosity of the base oil at 100 ° C. is not more than the above upper limit value, it is possible to improve fuel efficiency and improve the low temperature viscosity characteristics of the lubricating oil composition. Further, when the kinematic viscosity of the base oil at 100 ° C. is at least the above lower limit value, it is possible to sufficiently form an oil film at the lubricated portion and improve the lubricity. In the present specification, the "kinematic viscosity at 100 ° C." means the kinematic viscosity at 100 ° C. defined in ASTM D-445.

The kinematic viscosity of the lubricating oil base oil at 40 ° C. is preferably 40 mm ² / s or less, more preferably 30 mm ² / s or less, still more preferably 20 mm ² / s or less, and particularly preferably 15 mm ² / s or less. It is preferably 8.0 mm ² / s or more, more preferably 8.5 mm ² / s or more, and particularly preferably 9.0 mm ² / s or more. When the kinematic viscosity of the lubricating oil base oil at 40 ° C. is not more than the above upper limit value, it is possible to improve fuel efficiency and improve the low temperature viscosity characteristics of the lubricating oil composition. Further, when the kinematic viscosity of the base oil at 40 ° C. is at least the above lower limit value, it is possible to sufficiently form an oil film at the lubricated portion and improve the lubricity. In the present specification, the "kinematic viscosity at 40 ° C." means the kinematic viscosity at 40 ° C. defined in ASTM D-445.

The viscosity index of the lubricating oil base oil is preferably 100 or more. It is more preferably 110 or more, still more preferably 115 or more. When the viscosity index of the base oil is at least the above lower limit value, it is possible not only to improve the viscosity-temperature characteristics and the thermal / oxidation stability of the lubricating oil composition, but also to improve the wear prevention property. In addition, in this specification, a viscosity index means a viscosity index measured according to JIS K 2283-1993.

The pour point of the lubricating oil base oil is preferably -10 ° C or lower, more preferably -12.5 ° C or lower, still more preferably -15 ° C or lower, particularly preferably -17.5 ° C or lower, and most preferably -20 ° C. It is as follows. When the pour point exceeds the above upper limit value, the low temperature fluidity of the entire lubricating oil composition tends to decrease. In addition, in this specification, a pour point means a pour point measured in accordance with JIS K 2269-1987.

The sulfur content in the lubricating oil base oil is preferably 1.5% by mass or less, more preferably 1.0% by mass or less from the viewpoint of oxidative stability.

The lubricating oil base oil is (A1) API classification Group III or Group IV base oil (hereinafter sometimes referred to as "base oil (A1)"), which is 70% by mass or more and 99% by mass based on the total amount of lubricating oil base oil. It is preferable to include the following. The base oil (A1) is a group III base oil or a group IV base oil of the API classification, or a mixed base oil thereof. Group III base oils are mineral oil-based base oils having a sulfur content of 0.03% by mass or less, a saturation content of 90% by mass or more, and a viscosity index of 120 or more. Group IV base oils are polyα-olefins.

The lubricating oil base oil is an ester base oil having a kinematic viscosity of 3 mm ² / s or less at 100 ° C., a viscosity index of 130 or more, a flammable point of 200 ° C. or more, and a pour point of -30 ° C. or less. ) Is preferably contained in an amount of 1% by mass or more and 30% by mass or less based on the total amount of the lubricating oil base oil. When the content of the base oil (A2) is equal to or more than the above lower limit value, gears and bearings In addition, when the content of the base oil (A2) is equal to or less than the above upper limit value, the synchronization performance and peeling performance of the synchronizer ring and the transmission torque capacity of the wet clutch can be improved. It will be possible to increase.

As the base oil (A2), among the above ester base oils such as monoester base oil, diester base oil, polyester base oil, and polyol ester base oil, the kinematic viscosity at 100 ° C. is 3 mm ² / s or less and the viscosity index is 130 or more. , A flammable point of 200 ° C. or higher and a pour point of −30 ° C. or lower can be used, and a monoester base oil and / or a diester base oil can be preferably used.

The kinematic viscosity of the base oil (A2) at 100 ° C. is 3 mm ² / s or less, preferably 2.0 mm ² / s or more, and more preferably 2.5 mm ² / s or more. When the kinematic viscosity of the base oil (A2) at 100 ° C. is 3 mm ² / s or less, it becomes easy to improve fuel efficiency. Further, when the kinematic viscosity of the base oil (A2) at 100 ° C. is at least the above lower limit value, it becomes easy to sufficiently form an oil film at the lubricated portion and improve the lubricity.

The viscosity index of the base oil (A2) is 130 or more, more preferably 135 or more. When the viscosity index of the base oil (A2) is 130 or more, it becomes easy to enhance the low temperature fluidity of the lubricating oil composition and the oil film retention at high temperature. The upper limit of the viscosity index of the base oil (A2) is not particularly limited, but may be, for example, 300 or less.

The flash point of the base oil (A2) is 200 ° C. or higher, more preferably 210 ° C. or higher. When the flash point of the base oil (A2) is 200 ° C. or higher, the evaporation characteristics of the lubricating oil composition can be improved. The upper limit of the flash point of the base oil (A2) is not particularly limited, but may be, for example, 300 ° C. or lower.

The pour point of the base oil (A2) is −30 ° C. or lower, more preferably −35 ° C. or lower. When the pour point of the base oil (A2) is −30 ° C. or lower, it is possible to improve the low temperature startability. The lower limit of the pour point of the base oil (A2) is not particularly limited, but may be, for example, −100 ° C. or higher.

In the lubricating oil composition of the present invention, the content of the base oil (A1) in the lubricating oil base oil is 70% by mass or more and 99% by mass or less based on the total amount of the lubricating oil base oil, and the lubricating oil base oil. The content of the base oil (A2) in the oil is preferably 1% by mass or more and 30% by mass or less based on the total amount of the lubricating oil base oil. In such an embodiment, the content of the base oil other than the base oil (A1) and the base oil (A2) in the lubricating oil base oil is preferably 5% by mass or less based on the total amount of the lubricating oil base oil, and more preferably. It is 2% by mass or less, and may be 0% by mass. In the present specification, the content of the base oil other than the base oils (A1) and (A2) is 0% by mass, which means that the lubricating base oil is composed of the base oil (A1) and the base oil (A2). means.

<(B) Thiadiazole compound>
The lubricating oil composition of the present invention contains one or more thiadiazole compounds (hereinafter, may be referred to as "component (B)"). As the component (B), one type may be used alone, or two or more types may be used in combination.

Preferred examples of the component (B) include 1,3,4-thiadiazole represented by the following general formula (1), 1,2,4-thiadiazole compound represented by the following general formula (2), and the following general. 1 represented by the formula (3), 2,3 - can be exemplified thiadiazole compound.

(In the general formulas (1) to (3), R ¹ and R ² may be the same or different, and independently represent hydrogen or a hydrocarbyl group having 1 to 20 carbon atoms; a and b are the same or different. It may represent an integer from 0 to 8 independently.)

The content of the component (B) in the lubricating oil composition is such that the total sulfur content in the lubricating oil composition is 0.20% by mass or more based on the total amount of the lubricating oil composition. The upper limit of the total sulfur content in the lubricating oil composition (based on the total amount of the lubricating oil composition) is not particularly limited, but is preferably 0.45% by mass or less. By blending the component (B) so that the total sulfur content in the lubricating oil composition is 0.20% by mass or more, it becomes possible to improve wear resistance, seizure resistance, and fatigue life. .. Further, since the total sulfur content in the lubricating oil composition is 0.45% by mass or less, the S / P ratio described later is set to 8 or less, and wear resistance, wear resistance, fatigue life, and judder prevention of the wet clutch are prevented. It becomes easy to improve the property and the peelability of the brass synchronizer ring.

From the viewpoint of keeping the total sulfur content in the lubricating oil composition within the above range, the content of the component (B) itself in the lubricating oil composition is 0.05% by mass as the sulfur content based on the total amount of the lubricating oil composition. The above is preferable, and the content is preferably 0.35% by mass or less.

<(C) Phosphorus-containing friction modifier>
The lubricating oil composition of the present invention contains a phosphorus-containing friction modifier having a linear alkyl or alkenyl group having 12 or more carbon atoms (hereinafter, may be referred to as "component (C)"). As the component (C), one type may be used alone, or two or more types may be used in combination.

Examples of the component (C) include a phosphite ester represented by the following general formula (4), a phosphoric acid ester represented by the following general formula (5), and metal salts and ammonium salts thereof. And one or more selected from these can be preferably used. Among them, one or more selected from the phosphite ester represented by the following general formula (4), its metal salt and the ammonium salt can be particularly preferably used.

(In the general formulas (4) and (5), R ³ is a linear alkyl or alkenyl group having 12 or more carbon atoms, and R ⁴ is hydrogen or a linear alkyl or alkenyl group having 12 or more carbon atoms. R ³ and R ⁴ may be the same or different from each other.)

The carbon number of the "linear alkyl or alkenyl group having 12 or more carbon atoms" of the component (C) is preferably 4 or more, and is usually 30 or less, preferably 20 or less. When the number of carbon atoms is 12 or more, it is possible to improve the judder prevention property of the wet clutch and the peelability of the brass-based synchronizer ring.

The phosphorus compounds represented by the general formulas (4) and (5) are monoesters when R ⁴ is hydrogen, and diesters when R ⁴ is a linear alkyl or alkenyl group having 12 or more carbon atoms. .. The compounds represented by the general formulas (4) and (5) may be either monoesters or diesters, but are preferably diesters.

Examples of salts of phosphorus compounds represented by the general formulas (4) and (5) include the above phosphorus compounds, metal bases such as metal oxides, metal hydroxides, metal carbonates and metal chlorides, ammonia and carbon. A salt in which a part or all of the remaining acidic hydrogen is neutralized by allowing a nitrogen compound such as an amine compound having only a hydrocarbon group of several 1 to 30 or a hydroxyl group-containing hydrocarbon group in the molecule to act can be mentioned. it can.

Examples of metals in the above metal bases include alkali metals such as lithium, sodium, potassium and cesium, alkaline earth metals such as calcium, magnesium and barium, and heavy metals such as zinc, copper, iron, lead, nickel, silver and manganese. And so on. Among these, alkaline earth metals such as calcium and magnesium and zinc are preferable. In this specification, magnesium is also included in "alkaline earth metal".

Examples of the nitrogen compounds include ammonia, monoamines, diamines, polyamines, and alkanolamines. More specifically, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine. , Hexadecylamine, heptadecylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditri Decylamine, ditetradecylamine, dipentadecylamine, dihexadecylamine, diheptadecylamine, dioctadecylamine, methylethylamine, methylpropylamine, methylbutylamine, ethylpropylamine, ethylbutylamine, propylbutylamine, etc. Alkylamines with linear or branched alkyl groups with 1 to 30 carbon atoms; Alkenyl amines with linear or branched alkenyl groups with 2 to 30 carbon atoms, such as ethenylamines, propenylamines, butenylamines, octenylamines, and oleylamines; Methanolamine, ethanolamine, propanolamine, butanolamine, pentanolamine, hexanolamine, heptanolamine, octanolamine, nonanolamine, methanolethanolamine, methanolpropanolamine, methanolbutanolamine, ethanolpropanolamine, ethanolbutanolamine, And alkanolamines with linear or branched alkanol groups with 1 to 30 carbon atoms, such as propanol butanolamines; alkylenes with alkylene groups with 1 to 30 carbon atoms, such as methylenediamine, ethylenediamine, propylenediamine, and butylenediamines. Diamines; polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine; monoamines such as undecyldiethylamine, undecyldiethanolamine, dodecyldipropanolamine, oleyldiethanolamine, oleylpropylenediamine, stearyltetraethylenepentamine, etc. , Diamine, polyamine, alkanolamine and other amine compounds with hydrogen atoms and alkyl or alcohol with 8 to 20 carbon atoms. Compounds substituted with a kenyl group; heterocyclic compounds such as imidazoline; alkylene oxide adducts of these compounds; and mixtures thereof, and the like can be mentioned.

Among these nitrogen compounds, primary amines, secondary amines and alkanolamines are preferable, and the number of carbon atoms such as decylamine, dodecylamine, dimethyldodecylamine, tridecylamine, heptadecylamine, octadecylamine, oleylamine and stearylamine An aliphatic amine having 10 to 20 linear or branched alkyl or alkenyl groups is particularly preferred.

The content of the component (C) in the lubricating oil composition is 0.1% by mass or more, preferably 0.15% by mass or more, and preferably 2.0% by mass based on the total amount of the lubricating oil composition. Hereinafter, it is more preferably 1.5% by mass or less. When the content of the component (C) is at least the above lower limit value, it becomes possible to improve wear resistance, seizure resistance, fatigue life, and judder prevention property of the wet clutch. Further, when the content of the component (C) is not more than the above upper limit value, it becomes easy to increase the transmission torque capacity of the wet clutch.

<Phosphorus-containing additives other than (D) and (C) components>
The lubricating oil composition of the present invention contains a phosphorus-containing additive other than the above component (C) (hereinafter, may be referred to as "component (D)"). As the component (D), one type may be used alone, or two or more types may be used in combination.

As the component (D), a phosphorus-containing additive other than the above component (C) can be used without particular limitation. Examples of such phosphorus-containing additives include compounds represented by the following general formula (6), compounds represented by the following general formula (7), metal salts and ammonium salts thereof, and these. One or more selected from the above can be used.

(In general formula (6), X ¹ , X ² and X ³ independently represent an oxygen atom or a sulfur atom; R ⁵ represents a hydrocarbon group having 1 to 30 carbon atoms; R ⁶ and R ⁷ Represent each independently a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; R ⁵ , R ⁶ and R ⁷ may be the same or different from each other; at least one of R ⁶ and R ⁷ is a hydrogen atom. If it is, R ^{5, R 6,} and R ⁷ is a group other than "alkyl or alkenyl group having 12 or more linear carbon".)

(In general formula (7), X ⁴ , X ⁵ , X ⁶ and X ⁷ independently represent oxygen or sulfur atoms; R ⁵ , R ⁶ and R ⁷ are as defined above. )

Examples of hydrocarbon groups having 1 to 30 carbon atoms in the general formulas (6) and (7) include alkyl groups, cycloalkyl groups, alkenyl groups, alkyl-substituted cycloalkyl groups, aryl groups, alkyl-substituted aryl groups, and aryls. Alkyl groups and the like can be mentioned. The hydrocarbon group is preferably an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 24 carbon atoms, more preferably an alkyl group having 3 to 18 carbon atoms, and further preferably an alkyl group having 4 to 12 carbon atoms.

Examples of the salt of the phosphorus compound represented by the general formula (6) or (7) include metal oxides, metal hydroxides, metal carbonates, metal bases such as metal chlorides, ammonia, and 1 to 1 carbon atoms. Examples thereof include salts in which a nitrogen compound such as an amine compound having only 30 hydrocarbon groups or hydroxyl group-containing hydrocarbon groups in the molecule is allowed to act to neutralize a part or all of the remaining acidic hydrogen.

Specific examples of the metal forming a metal salt with the phosphorus compound represented by the general formula (6) or (7) include alkali metals such as lithium, sodium, potassium and cesium, calcium, magnesium and barium. Alkaline earth metals, heavy metals such as zinc, copper, iron, lead, nickel, silver and manganese. Among these, alkaline earth metals such as calcium and magnesium and zinc are preferable.

Examples of the nitrogen compound forming an ammonium salt with the phosphorus compound represented by the general formula (6) or (7) include ammonia, monoamine, diamine, polyamine and the like, and more specifically, the component (C). The same nitrogen compounds as described above can be mentioned in relation to.

The content of the component (D) in the lubricating oil composition is such that the total phosphorus content in the lubricating oil composition is 0.04% by mass or more based on the total amount of the lubricating oil composition. When the total phosphorus content in the lubricating oil composition is 0.04% by mass or more, it is possible to improve wear resistance, seizure resistance, fatigue life, and judder prevention property of the wet clutch. The total phosphorus content in the lubricating oil composition is preferably 0.15% by mass or less, more preferably 0.09% by mass or less, based on the total amount of the lubricating oil composition. When the total phosphorus content in the lubricating oil composition is not more than the above upper limit value, it is possible to improve wear resistance, seizure resistance, fatigue life, and judder prevention property of the wet clutch.

From the viewpoint of setting the total phosphorus content in the lubricating oil composition to the above lower limit value or more, the content of the component (D) itself in the lubricating oil composition is 0.02 mass as the phosphorus content based on the total amount of the lubricating oil composition. % Or more is preferable.

<(E) Poly (meth) acrylate>
The lubricating oil composition of the present invention contains a poly (meth) acrylate having a weight average molecular weight of 50,000 or less (hereinafter, may be referred to as “component (E)”). In addition, in this specification, "(meth) acrylate" means "acrylate and / or methacrylate".

The component (E) may be a dispersed poly (meth) acrylate or a non-dispersed poly (meth) acrylate. The weight average molecular weight of the component (E) is 50,000 or less, preferably 10,000 or more, and more preferably 15,000 or more. When the weight average molecular weight of the component (E) is 50,000 or less, the shear stability of the lubricating oil composition can be enhanced. Further, when the weight average molecular weight of the component (E) is at least the above lower limit value, it becomes easy to increase the viscosity index of the lubricating oil composition.

The component (E) acts as a viscosity index improver. The content of the component (E) in the lubricating oil composition can be such that the kinematic viscosity and viscosity index of the lubricating oil composition at 40 ° C. are within the range described later. The specific content varies depending on the weight average molecular weight of the component (E), but can be, for example, 3 to 20% by mass based on the total amount of the lubricating oil composition (100% by mass).

<(F) Calcium-based cleaning agent>
In one preferred embodiment, the lubricating oil composition of the present invention may further comprise a calcium-based cleaning agent (hereinafter sometimes referred to as "component (F)"). As the component (F), one type may be used alone, or two or more types may be used in combination.

As the component (F), known calcium-based cleaning agents such as calcium sulfonate, calcium phenate, and calcium salicylate can be used, and calcium sulfonate can be preferably used.

As the calcium sulfonate cleaning agent, a calcium salt of an alkyl aromatic sulfonic acid obtained by sulfonated an alkyl aromatic compound or a basic salt or a hyperbasic salt thereof can be preferably exemplified. The weight average molecular weight of the alkyl aromatic compound is preferably 400 to 1500, more preferably 700 to 1300.
Examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid. Examples of the petroleum sulfonic acid referred to here include sulfonated alkyl aromatic compounds in the lubricating oil fraction of mineral oil, so-called mahoganic acid, which is by-produced during the production of white oil. Further, as an example of synthetic sulfonic acid, a linear or branched alkyl obtained by recovering a by-product in an alkylbenzene production plant which is a raw material of a detergent or by alkylating benzene with polyolefin. Examples thereof include sulfonated alkylbenzenes having a group. As another example of the synthetic sulfonic acid, an alkylnaphthalene such as dinonylnaphthalene sulfonated can be mentioned. Further, the sulfonate agent for sulfonated these alkyl aromatic compounds is not particularly limited, and for example, fuming sulfuric acid or anhydrous sulfuric acid can be used.

As the calcium phenate cleaning agent, a hyperbasic salt of a calcium salt of a compound having a structure represented by the following general formula (8) can be preferably exemplified.

In the general formula (8), R ⁸ represents a linear or branched chain having 6 to 21 carbon atoms, a saturated or unsaturated alkyl group or an alkenyl group, and c represents a degree of polymerization and represents an integer of 1 to 10. A represents a sulfide (-S-) group or a methylene (-CH _2- ) group, and d represents an integer of 1 to 3. R ⁸ may be a combination of two or more different groups.

The number of carbon atoms of ^{R 8} in the general formula (8) is preferably 9 to 18, more preferably 9 to 15. If the carbon number of R ⁸ is less than 6, the solubility in the base oil may be inferior, while if the carbon number of R ⁸ exceeds 21, production may be difficult and the heat resistance may be inferior.

The degree of polymerization c in the general formula (8) is preferably 1 to 3. When the degree of polymerization c is within this range, heat resistance can be enhanced.

As the calcium salicylate cleaning agent, calcium salicylate or a basic salt or a hyperbasic salt thereof can be preferably exemplified. As the calcium salicylate referred to here, a compound represented by the following general formula (9) can be preferably exemplified.

In the above general formula (9), R ⁹ independently represents an alkyl group or an alkenyl group having 14 to 30 carbon atoms, and e represents 1 or 2, preferably 1. When e = 2, R ⁹ may be a combination of different groups.

The method for producing an alkaline earth metal salicylate is not particularly limited, and a known method for producing a monoalkyl salicylate or the like can be used. For example, phenol is used as a starting material for archylation using an olefin, and then monoalkylsalicylic acid obtained by carboxylating with carbon dioxide or the like, or salicylic acid is used as a starting material and an equivalent amount of the above olefin is used for archylation. The obtained monoalkylsalicylic acid or the like is reacted with a metal base such as an oxide of an alkaline earth metal or a hydroxide, or these monoalkylsalicylic acids or the like are once used as an alkali metal salt such as a sodium salt or a potassium salt. Alkaline earth metal salicylate can be obtained by exchanging metal with an alkaline earth metal salt.

The base value of the component (F) is preferably 100 to 500 mgKOH / g.
The metal ratio of the component (F) is a value calculated according to the following formula, preferably 1.0 or more, and preferably 2.0 or less.
Metal ratio of component (F) = Metal content of component (F) (mol) x valence of metal element in component (F) / soap group content of component (F) (mol)

When the lubricating oil composition contains the component (F), the content thereof is such that the total calcium content in the lubricating oil composition is 0.01% by mass or less based on the total amount of the lubricating oil composition. The total calcium content in the lubricating oil composition is preferably 0.006% by mass or less. When the total calcium content in the lubricating oil composition is 0.01% by mass or less, the seizure resistance and the fatigue life can be further improved. The total calcium content in the lubricating oil composition may be 0% by mass, but from the viewpoint of long drainage, it is preferably 0.001% by mass or more based on the total amount of the lubricating oil composition, and more preferably 0. It is 002% by mass or more.

From the viewpoint of keeping the total calcium content in the lubricating oil composition within the above range, the content of the component (F) itself in the lubricating oil composition is 0.002% by mass as the calcium content based on the total amount of the lubricating oil composition. The above is preferable, and the content is preferably 0.01% by mass or less.

<(G) Aliphatic amide compound>
In one preferred embodiment, the lubricating oil composition of the present invention may further comprise an aliphatic amide compound (hereinafter sometimes referred to as "component (G)"). The component (G) acts as an ashless friction modifier. As the component (G), one type may be used alone, or two or more types may be used in combination.

As the component (G), an aliphatic amide compound which is a condensation product of a fatty acid and an ammonia or an aliphatic amine compound can be preferably used. The fatty acid used as a raw material for the aliphatic amide compound usually has 10 to 30 carbon atoms, preferably 13 or more, more preferably 16 or more, and preferably 26 or less, more preferably 24 or less. When the number of carbon atoms of the fatty acid is less than 10, the friction adjusting action is poor, and when the number of carbon atoms exceeds 30, the low temperature viscosity characteristics of the lubricating oil composition may be deteriorated. The hydrocarbon group bonded to the carboxy group of the fatty acid may be an alkyl group or an alkenyl group .

Amine as a raw material for the aliphatic amide compounds, ammonia, primary aliphatic amines, may be any of secondary aliphatic amines, primary aliphatic amines are preferred. Examples of primary aliphatic amines, may be mentioned monoalkyl amines, mono- alkanolamines, diamines typified by e ethylenediamine.

Examples of the preferred aliphatic amide compound as the component (G) are selected from lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, eikosanoic acid, bechenic acid and lignoceric acid. mention may be made of the fatty acids or their mixtures, ammonia, methylamine, ethylamine, ethanolamine, the condensation reaction product of d ethylenediamine or mixtures thereof. Fatty amide compounds, primary amide, secondary amide, but it may also be any of the tertiary amide.

When the lubricating oil composition contains the component (G), the content thereof is 0.3 to 1.0% by mass based on the total amount of the lubricating oil composition. When the content of the component (G) is 0.3% by mass or more, the fatigue life and the judder prevention property of the wet clutch can be further improved. Further, when the content of the component (G) is 1.0% by mass or less, the synchronization performance of the synchronizer ring can be further improved.

<(H) Ash-free dispersant>
In one preferred embodiment, the lubricating oil composition may further comprise an ashless dispersant (hereinafter sometimes referred to as "component (H)").

As the component (H), for example, one or more compounds selected from the following (H-1) to (H-3) can be used.
(H-1) Imide succinate having at least one alkyl group or alkenyl group in the molecule or a derivative thereof (hereinafter, may be referred to as "(G-1) component"),.
(H-2) Benzylamine having at least one alkyl group or alkenyl group in the molecule or a derivative thereof (hereinafter, may be referred to as "(G-2) component"),
(H-3) A polyamine having at least one alkyl group or alkenyl group in the molecule or a derivative thereof (hereinafter, may be referred to as "(G-3) component").

As the component (H), the component (H-1) can be particularly preferably used.
Among the components (H-1), examples of the succinate imide having at least one alkyl group or alkenyl group in the molecule include a compound represented by the following general formula (10) or (11).

In formula (10), R ¹⁰ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, and f represents an integer of 1 to 5, preferably 2 to 4. The carbon number of R ¹⁰ is preferably 60 or more, and preferably 350 or less.

In formula (11), R ¹¹ and R ¹² each independently represent an alkyl group or an alkenyl group having 40 to 400 carbon atoms, and may be a combination of different groups. R ¹¹ and R ¹² are particularly preferably polybutenyl groups. Further, g represents an integer of 0 to 4, preferably 1 to 3. The carbon number of R ¹¹ and R ¹² is preferably 60 or more, and preferably 350 or less.

When the number of carbon atoms of R ^{10 to} R ¹² in the formulas (10) and (11) is not more than the above lower limit value, good solubility in the lubricating oil base oil can be obtained. On the other hand, when the number of carbon atoms of R ^{10 to} R ¹² is not more than the above upper limit value, the low temperature fluidity of the lubricating oil composition can be enhanced.

The alkyl group or alkenyl group (R ^{10 to} R ¹¹ ) in the formula (10) and the formula (11) may be linear or branched, and is preferably an oligomer of an olefin such as propylene, 1-butene, or isobutene. Examples thereof include branched alkyl groups and branched alkenyl groups derived from co-oligomers of ethylene and propylene. Of these, a branched alkyl group or alkenyl group commonly derived from an oligomer of isobutene commonly called polyisobutylene, or a polybutenyl group is most preferable.
Suitable number average molecular weights of alkyl or alkenyl groups (R ^{10 to} R ¹² ) in formulas (10) and (11) are 800 to 3500.

A so-called monotype succinic acid imide represented by the formula (10) in which succinic anhydride is added to only one end of a polyamine chain to an succinic anhydride having at least one alkyl group or alkenyl group in the molecule. And the so-called bis-type succinic anhydride imide represented by the formula (11), in which succinic anhydride is added to both ends of the polyamine chain, are included. The lubricating oil composition may contain either a monotype succinate imide or a bis-type succinate imide, and both of them may be contained as a mixture.

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

Among the components (H-2), examples of the benzylamine having at least one alkyl group or alkenyl group in the molecule include a compound represented by the following general formula (12).

In formula (12), R ¹³ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, and h represents an integer of 1 to 5, preferably 2 to 4. The carbon number of R ¹³ is preferably 60 or more, and preferably 350 or less.

The method for producing the component (H-2) is not particularly limited. For example, a polyolefin such as a propylene oligomer, a polybutene, or an ethylene-α-olefin copolymer is reacted with phenol to obtain an alkylphenol, which is then combined with formaldehyde, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine. Examples thereof include a method of reacting with a polyamine such as the above by a Mannich reaction.

As the polyamine having at least one alkyl group or alkenyl group in the molecule among the components (H-3), a compound represented by the following formula (13) can be exemplified.

In formula (13), R ¹⁴ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, and i represents an integer of 1 to 5, preferably 2 to 4. The carbon number of R ¹⁴ is preferably 60 or more, and preferably 350 or less.

The method for producing the component (H-3) is not particularly limited. For example, after chlorinating a polyolefin such as propylene oligomer, polybutene or ethylene-α-olefin copolymer, it is reacted with polyamine such as ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine. The method can be mentioned.

Derivatives in the components (H-1) to (H-3) include, for example, (i) an imide succinate, a benzylamine or a polyamine having at least one alkyl group or alkenyl group described above in the molecule (hereinafter, “described above”. Nitrogen-containing compounds "), monocarboxylic acids having 1 to 30 carbon atoms such as fatty acids, and polycarboxylic acids having 2 to 30 carbon atoms (for example, oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc.) , These anhydrides or ester compounds, alkylene oxides having 2 to 6 carbon atoms, or hydroxy (poly) oxyalkylene carbonate are allowed to act to neutralize some or all of the remaining amino groups and / or imino groups. Alternatively, an amidated modified compound with an oxygen-containing organic compound; (ii) By allowing boric acid to act on the above-mentioned nitrogen-containing compound, some or all of the remaining amino groups and / or imino groups are neutralized or Amidated boron-modified compound; (iii) By allowing phosphoric acid to act on the above-mentioned nitrogen-containing compound, some or all of the remaining amino groups and / or imino groups are neutralized or amidated. , Phosphate-modified compound; (iv) Sulfur-modified compound obtained by reacting the above-mentioned nitrogen-containing compound with a sulfur compound; and (v) Modification of the above-mentioned nitrogen-containing compound with an oxygen-containing organic compound, boron-modified, Examples thereof include modified compounds obtained by applying a combination of two or more types of modifications selected from phosphate modification and sulfur modification. Among these derivatives (i) to (v), it is preferable to use the boron-modified compound of the component (H-1) in that the heat resistance of the lubricating oil composition can be further improved.

The molecular weight of the component (H) is not particularly limited, but a suitable weight average molecular weight is 1000 to 20000.

When the lubricating oil composition contains the component (H), the content thereof is preferably 0.01 to 0.20% by mass, more preferably 0.05 as a nitrogen content based on the total amount of the lubricating oil composition. It is mass% or more, and more preferably 0.10 mass% or less. When the content of the component (H) is at least the above lower limit value, the caulking resistance (heat resistance) of the lubricating oil composition can be enhanced. Further, when the content of the component (H) is not more than the above upper limit value, it becomes possible to further improve the fuel efficiency.

When a boron-modified compound is used as the component (H), the amount of boron derived from the component (H) in the lubricating oil composition is preferably 0.001 to 0.05% by mass based on the total amount of the lubricating oil composition. It is more preferably 0.005% by mass or more, and more preferably 0.03% by mass or less. When the boron content derived from the component (H) is not more than the above upper limit value, it is possible to further improve fuel efficiency.

<Other additives>
In one embodiment, the lubricating oil composition comprises a wear inhibitor or extreme pressure agent other than the components (B), (C), and (D), an antioxidant, a pour point lowering agent other than the component (E), It may further contain one or more selected from corrosion inhibitors and rust inhibitors other than the component (B), metal inactivating agents other than the component (B), defoaming agents, anti-emulsifiers, and colorants.

Examples of the anti-wear agent or extreme pressure agent other than the components (B), (C) and (D) include sulfur compounds such as disulfides, olefins sulfides and oils and fats sulfides. When the lubricating oil composition contains an anti-wear agent or an extreme pressure agent other than the components (B), (C) and (D), the content thereof is usually 0.01 to 5 based on the total amount of the lubricating oil composition. It is mass%.

Examples of the antioxidant include ashless antioxidants such as phenols and amines, and metal-based antioxidants such as copper and molybdenum. Specifically, for example, examples of the phenolic ashless antioxidant include 4,4'-methylenebis (2,6-di-tert-butylphenol) and 4,4'-bis (2,6-di-tert-butylphenol). ), Etc., and examples of the amine-based antioxidant are phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, dialkyldiphenylamine and the like. When the lubricating oil composition contains an antioxidant, the content thereof is usually 0.01 to 5% by mass based on the total amount of the lubricating oil composition.

As the pour point lowering agent other than the component (E), a known pour point lowering agent such as a polymethacrylate-based polymer can be used depending on the properties of the lubricating oil base oil used. When the lubricating oil composition contains a pour point lowering agent, the content thereof is usually 0.05 to 1% by mass based on the total amount of the lubricating oil composition.

As the corrosion inhibitor other than the component (B), for example, known corrosion inhibitors such as benzotriazole-based, tolyltriazole-based, and imidazole-based compounds can be used. When the lubricating oil composition contains a corrosion inhibitor other than the component (E), the content thereof is usually 0.005 to 5% by mass based on the total amount of the lubricating oil composition.

As the rust preventive, known rust preventives such as petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester can be used. When the lubricating oil composition contains a rust preventive, the content thereof is usually 0.005 to 5% by mass based on the total amount of the lubricating oil composition.

Examples of the metal inactivating agent other than the component (B) include imidazoline, a pyrimidine derivative, mercaptobenzothiazole, benzotriazole and its derivative, 2- (alkyldithio) benzimidazole, and β- (o-carboxybenzylthio). A known metal inactivating agent such as propionnitrile can be used. When the lubricating oil composition contains a metal inactivating agent other than the component (E), the content thereof is usually 0.005 to 1% by mass based on the total amount of the lubricating oil composition.

As the defoaming agent, for example, known defoaming agents such as silicone, fluorosilicone, and fluoroalkyl ether can be used. When the lubricating oil composition contains a defoaming agent, the content thereof is usually 0.0005 to 1% by mass based on the total amount of the lubricating oil composition.

As the anti-emulsifier, a known anti-emulsifier such as a polyalkylene glycol-based nonionic surfactant can be used. When the lubricating oil composition contains an anti-emulsifier, the content thereof is usually 0.005 to 5% by mass based on the total amount of the lubricating oil composition.

As the colorant, a known colorant such as an azo compound can be used.

<Lubricating oil composition>
The kinematic viscosity of the lubricating oil composition at 40 ° C. is 25 mm ² / s or less. Further, it is preferably 10 mm ² / s or more, more preferably 15 mm ² / s or more, and further preferably 20 mm ² / s or more. When the kinematic viscosity of the lubricating oil composition at 40 ° C. is 25 mm ² / s or less, it is possible to improve fuel efficiency. Further, when the kinematic viscosity of the lubricating oil composition at 40 ° C. is at least the above lower limit value, it becomes easy to sufficiently form an oil film at the lubricated portion and enhance the wear resistance.

The kinematic viscosity of the lubricating oil composition at 100 ° C. is preferably 5.0 mm ² / s or more, preferably 9.0 mm ² / s or less, more preferably 8.0 mm ² / s or less, still more preferably 7. It is 0.0 mm ² / s or less. When the kinematic viscosity of the lubricating oil composition at 100 ° C. is at least the above lower limit value, it becomes easy to sufficiently form an oil film at the lubricated portion and enhance the wear resistance. Further, when the kinematic viscosity of the lubricating oil composition at 100 ° C. is not more than the above upper limit value, it becomes easy to improve fuel efficiency.

The viscosity index of the lubricating oil composition is 170 or more. When the viscosity index of the lubricating oil composition is 170 or more, it becomes easy to improve fuel efficiency. The upper limit of the viscosity index of the lubricating oil composition is not particularly limited, but is usually 250 or less.

The mass ratio S / P of the total sulfur content S (unit: mass%) in the lubricating oil composition and the total phosphorus content P (unit: mass%) in the lubricating oil composition shall be 3 or more and 8 or less. Is preferable. When the ratio S / P is 3 or more, it becomes possible to further improve the wear resistance, the seizure resistance, the fatigue life, and the transmission torque capacity of the wet clutch. Further, when the ratio S / P is 8 or less, it becomes possible to further improve the wear resistance, the seizure resistance, the fatigue life, the judder prevention property of the wet clutch, and the peeling property of the synchronizer ring.

The Brookfield viscosity (hereinafter sometimes referred to as “BF viscosity”) of the lubricating oil composition at −40 ° C. is preferably 10,000 mPa · s or less, and more preferably 9,000 mPa · s or less. When the BF viscosity of the lubricating oil composition at −40 ° C. is 10,000 mPa · s or less, it is possible to improve the low temperature startability.

(Use)
The lubricating oil composition of the present invention can be preferably used as an automatic transmission oil for automobiles, and can be particularly preferably used for lubricating an automatic transmission provided with a synchro mechanism, for example, a dual clutch transmission.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the present invention is not limited to these examples.

<Examples 1 to 17 and Comparative Examples 1 to 5>
As shown in Tables 1 to 3, the gear oil composition of the present invention (Examples 1 to 17) and the gear oil composition for comparison (Comparative Examples 1 to 5) were prepared, respectively. In the table, the content of the base oil is based on the total amount of the base oil, and the content of each additive is based on the total amount of the composition. The details of the ingredients are as follows.

((A) Lubricating oil base oil)
A1-1: Wax isomerized base oil (Group III, kinematic viscosity (40 ° C): 9.072 mm ² / s, kinematic viscosity (100 ° C): 2.621 mm ² / s, viscosity index: 127, sulfur content: 10 less mass _{ppm,% C P: 91.8,} % C N: 8.2,% C A: 0)
A1-2: Wax isomerized base oil (Group III, kinematic viscosity (40 ° C): 15.65 mm ² / s, kinematic viscosity (100 ° C): 3.883 mm ² / s, viscosity index: 142, sulfur content: 10 less mass _{ppm,% C P: 92.5,} % C N: 7.5,% C A: 0)
A1-3: Hydrogenated refined mineral oil (kinematic viscosity (40 ° C): 12.43 mm ² / s, kinematic viscosity (100 ° C): 3.12 mm ² / s, viscosity index: 112, sulfur content: less than 10 mass ppm)
A1-4: Hydrorefined mineral oil (Group III, kinematic viscosity (40 ° C): 19.57 mm ² / s, kinematic viscosity (100 ° C): 4.23 mm ² / s, viscosity index: 122, sulfur content: 10 mass less than _{ppm,% C P: 80.7,} % C N: 19.3,% C A: 0)
A1-5: Poly α-olefin (Group IV, kinematic viscosity (40 ° C): 5 mm ² / s, kinematic viscosity (100 ° C): 1.7 mm ² / s, viscosity index: 91, pour point: -66 ° C, Flash point: 157 ° C)
A1-6: Poly α-olefin (Group IV, kinematic viscosity (40 ° C): 19 mm ² / s, kinematic viscosity (100 ° C): 4.1 mm ² / s, viscosity index: 126, pour point: -66 ° C, Flash point: 220)
A2-1: Diester base oil (Group V, 2-ethylhexyl azelaic acid, kinematic viscosity (40 ° C): 10.3 mm ² / s, kinematic viscosity (100 ° C): 2.9 mm ² / s, viscosity index: 138, Pour point: -72 ° C, ignition point: 220 ° C)
A2-2: Monoester base oil (Group V, 2-ethylhexyl oleate, kinematic viscosity (40 ° C): 8.4 mm ² / s, kinematic viscosity (100 ° C): 2.7 mm ² / s, viscosity index: 174 , Pour point: -40 ° C, ignition point: 224 ° C)

((B) Thiadiazole compound)
B-1: Thiadiazole compound having a hydrocarbyl dithio group represented by the general formulas (1) to (3), S: 36% by mass.

((C) Phosphorus-containing friction modifier)
C-1: Acidic phosphite ester having an alkyl or alkenyl group having 18 carbon atoms, P: 5.8% by mass
C-2: Amine salt of acidic phosphite ester having an alkyl or alkenyl group having 18 carbon atoms, P: 2.45% by mass

((E) Poly (meth) acrylate)
E-1: Non-dispersed polymethacrylate, weight average molecular weight: 20,000
E-2: Dispersed polymethacrylate, weight average molecular weight: 40,000
E-3: Dispersed polymethacrylate, weight average molecular weight: 150,000

((F) Calcium-based cleaning agent)
F-1: Ca sulfonate, base value 300 mgKOH / g, Ca: 12.2% by mass

((G) Aliphatic amide compound)
G-1: condensation products of fatty acids and fatty Zokua Min, N: 6.2 wt%

((D) Phosphorus-containing additive other than the above component (C), and (H) Ash-free dispersant)
Additive package: Afton Chemical Hitec (registered trademark) 403J, B: 0.24% by mass, N: 1.55% by mass, P: 0.51% by mass, S: 2.23% by mass

(Other additives)
Rubber swelling agent: Sulfur-containing rubber swelling agent, S: 11.6% by mass
Defoamer: Dimethyl silicone

(Low temperature viscosity characteristics)
For each of the lubricating oil compositions, the viscosity (BF viscosity) at an oil temperature of −40 ° C. was measured using a Brookfield viscometer. The results are shown in Tables 1-3. The lower the BF viscosity at −40 ° C., the better the low temperature startability. The BF viscosity at −40 ° C. is preferably 10,000 mPa · s or less.

(Shear stability test)
The shear stability of the lubricating oil composition was evaluated by a shear stability test in accordance with JPI-5S-29-88 for each of the lubricating oil compositions. The sample oil is irradiated with ultrasonic waves having a frequency of 10 kHz and a swing width of 28 μm from the vibrator for 2 hours, and the kinematic viscosity of the sample oil after ultrasonic irradiation at 100 ° C. is measured at 100 ° C. of the sample oil before ultrasonic irradiation. The rate of decrease (%) with respect to the kinematic viscosity was calculated. The results are shown in Tables 1-3. The lower the rate of decrease in kinematic viscosity, the higher the shear stability and the better the durability. In this test, the rate of decrease in kinematic viscosity is preferably 2.0% or less.

(High-speed walk test)
For each of the lubricating oil compositions, the load bearing capacity and wear resistance of the lubricating oil composition were evaluated by a high-speed walk test in accordance with JPI-5S-40-93.
(1) The final non-seizure load (LNSL) was measured at a rotation speed of 1800 rpm.
(2) The wear mark diameter after operating at a rotation speed of 1200 rpm, a load of 392 N, and an oil temperature of 80 ° C. for 30 minutes was measured.
The results are shown in Tables 1-3. The higher the LNSL, the better the seizure resistance (load bearing capacity), and the smaller the wear mark diameter, the better the wear resistance. In this test, the LNSL is preferably 618 N or more, and the wear mark diameter is preferably 0.60 mm or less.

(FALEX seizure test)
For each of the lubricating oil compositions, the load bearing capacity of the gear oil composition was evaluated by a FALEX seizure test in accordance with ASTM D3233. Under the condition of an oil temperature of 110 ° C., a steel pin sandwiched between two stationary steel V blocks was rotated at 290 rpm, and the load at which seizure occurred was measured. The results are shown in Tables 1-3. The larger the load at which seizure occurs, the better the seizure resistance (load bearing capacity). The load-bearing capacity measured in this test is preferably 4400 N or more.

(Unisteel test)
Unisteel test (British Petroleum Society method: IP305) was used for each of the lubricating oil compositions using a Unisteel rolling fatigue tester (Tokyo Testing Machine Co., Ltd. triple high temperature rolling fatigue tester TRF-1000 / 3-01H). The rolling fatigue life of the thrust bearing was measured according to / 79). For a test bearing in which the raceway ring on one side of the thrust needle bearing (FNTA-2542C manufactured by NSK) is replaced with a flat test piece (material: SUJ2), the conditions are a load of 7000 N, a surface pressure of 2 GPa, a rotation speed of 1450 rpm, and an oil temperature of 120 ° C. Below, the time until either the roller or the test piece was fatigue-damaged was measured. When the vibration acceleration of the test unit measured by the vibration accelerometer provided in the Unisteel rolling fatigue tester reached 1.5 m / s ² , it was determined that fatigue damage had occurred. From the time until fatigue damage in 10 repeated tests, the fatigue life was calculated as 50% life (L50: time when the cumulative probability becomes 50%) by the Weibull plot. The results are shown in Tables 1-3. The longer the 50% life measured in this test, the more the fatigue life of gears and bearings can be improved. The fatigue life (50% life) measured in this test is preferably 1100 minutes or more.

(SAE No. 2 friction test)
For each of the lubricating oil compositions, SAE No. 2 Using a testing machine (manufactured by Shinko Engineering Co., Ltd.), a dynamic friction test was performed in accordance with JASO M348: 2002, and the dynamic friction coefficients μ _d and μ ₀ between the friction plate and the steel plate were measured, and the ratio μ ₀ / μ _d. Was calculated.
The results are shown in Tables 1-3. The larger the dynamic friction coefficient mu _d measured in this study, the fastening performance of the wet clutch is good, that means that a large transmission torque capacity of the wet clutch. Further, the smaller the ratio μ ₀ / μ _{d, the} better the judder prevention property of the wet clutch. The dynamic friction coefficient μ _d measured in this test is preferably 0.125 or more, and the ratio μ ₀ / μ _d is preferably 0.95 or less.

(Synchronizer ring unit test)
For each of the lubricating oil compositions, the dynamic friction coefficient and stick torque exhibited by the brass synchronizer ring were measured using a simple substance friction tester for the synchronizer ring (manufactured by Shinko Engineering Co., Ltd.).
The synchronizer ring unit tester has a synchronizer ring and a gear cone provided coaxially, the synchronizer ring is movably held in the axial direction, and the gear cone is held so that it can be rotationally driven.
The procedure for measuring the coefficient of dynamic friction is as follows. A steel gear cone (inertial mass 0.16 kg ・ m ² ) rotating at a predetermined rotation speed (300 rpm) in lubricating oil (oil temperature 60 ° C.) and a brass synchronizer ring (cone angle 6.3 °, An effective radius of 27 mm) is pressed with a predetermined load (500 N). The dynamic friction coefficient was calculated from the friction torque at the 500th cycle, with the process of pressing for 0.2 seconds and then pulling away for 2.0 seconds as one cycle.
The procedure for measuring the stick torque is as follows. First, the rotation is stopped by pressing the synchronizer ring against the gear cone that freely rotates at an initial speed of 300 rpm in the same manner as in the above measurement procedure of the dynamic friction coefficient. When the rotation stops, the synchronizer ring is stuck to the gear cone. Next, the gear cone is rotated at a predetermined rotation speed (300 rpm) with no load applied to the synchronizer ring, and the torque (stick torque) when the synchronizer ring is peeled off from the mating member is measured. As the measured value, the maximum value of up to 10 measurements was taken.
The results are shown in Tables 1-3. The larger the coefficient of dynamic friction measured in this test, the better the synchronization performance of the synchronizer ring. Further, the smaller the stick torque measured in this test, the better the peelability of the synchronizer ring. The dynamic friction coefficient measured in this test is preferably 0.140 or more, the stick torque is preferably 10 or less, and particularly preferably 5 or less.

(Evaluation results)
The lubricating oil compositions of Examples 1 to 17 showed good results in all the evaluation items.
The composition of Comparative Example 1 in which the kinematic viscosity and viscosity index of the composition at 40 ° C. were outside the range of the present invention was inferior in low temperature viscosity characteristics.
The composition of Comparative Example 2 which did not contain the component (B) (thiadiazole compound) and had an excessively small S / P ratio of the composition had a wear mark diameter (wear resistance) in a high-speed walk test and a FALEX seizure test. (Load capacity) and Unisteel test (fatigue life) showed inferior results.
The composition of Comparative Example 3 which did not contain the component (C) (phosphorus-containing friction modifier) and had an excessive S / P ratio of the composition had a wear mark diameter (wear resistance) and FALEX in a high-speed walk test. Seizure test (load bearing capacity), Unisteel test (fatigue life), and SAE No. In the two friction test, the result was inferior in the μ ₀ / μ _d ratio (judgment prevention property of the wet clutch).
The composition of Comparative Example 4 which did not contain the component (B) and the component (C) had a wear mark diameter (wear resistance), a FALEX seizure test (load bearing capacity), and a unit steel test (fatigue) in a high-speed walk test. The results were inferior in the dynamic friction coefficient (synchronization performance of the synchronizer ring) and the stick torque (peelability of the synchronizer ring) in the unit test of the synchronizer ring.
The composition of Comparative Example 5 in which the weight average molecular weight of the component (E) (poly (meth) acrylate) was excessive was a shear stability test, a FALEX seizure test (load bearing capacity), and a unistell test (fatigue life). ) Showed inferior results.

Claims (6)

(A) As the lubricating oil base oil, one or more mineral oil-based base oils, one or more synthetic base oils, or a mixture thereof.
(B) The amount of the thiadiazole compound so that the total sulfur content in the lubricating oil composition is 0.20% by mass or more based on the total amount of the lubricating oil composition.
(C) A phosphorus-containing friction modifier having a linear alkyl or alkenyl group having 12 or more carbon atoms is added to 0.1% by mass or more based on the total amount of the lubricating oil composition.
(D) The amount of the phosphorus-containing additive other than the component (C) is such that the total phosphorus content in the lubricating oil composition is 0.04% by mass or more based on the total amount of the lubricating oil composition.
(E) Containing poly (meth) acrylate having a weight average molecular weight of 50,000 or less,
The ratio S / P of the total sulfur content S in the lubricating oil composition to the total phosphorus content P in the lubricating oil composition is 3 or more and 8 or less.
The lubricating oil composition has a kinematic viscosity of 25 mm ² / s or less at 40 ° C. and a viscosity index of 170 or more.
Lubricating oil composition for automatic transmissions having a synchro mechanism. The kinematic viscosity of the lubricating oil base oil (A) at 100 ° C. is 3.3 mm ² / s or less.
The lubricating oil composition according to claim 1. The (A) lubricating oil base oil is (A2) an ester base oil having a kinematic viscosity of 3 mm ² / s or less at 100 ° C., a viscosity index of 130 or more, a flammable point of 200 ° C. or more, and a pour point of -30 ° C. or less. Contains 1% by mass or more and 30% by mass or less based on the total amount of base oil.
The lubricating oil composition according to claim 1 or 2 . The (A) lubricating oil base oil contains polyα-olefin or a hydride thereof, a hydrocracked mineral oil-based base oil, and / or a wax-isomerized isoparaffin-based base oil in an amount of 70% by mass or more based on the total amount of the lubricating oil base oil. Including 99% by mass or less,
The lubricating oil composition according to claim 3 . (F) The calcium-based cleaning agent is contained in an amount such that the total calcium content in the lubricating oil composition is 0.01% by mass or less based on the total amount of the lubricating oil composition.
The lubricating oil composition according to any one of claims 1 to 4 . (G) An aliphatic amide compound having a linear alkyl or alkenyl group having 12 or more carbon atoms is contained in an amount of 0.3% by mass or more and 1.0% by mass or less based on the total amount of the lubricating oil composition.
The lubricating oil composition according to any one of claims 1 to 5 .