KR20070102958A - Lubricant compositions for an automatic transmission - Google Patents

Abstract

A lubricant composition for an automatic transmission is provided to improve durability of the friction characteristic, fuel efficiency, and the fatigue life time of a gear. A lubricant composition for an automatic transmission consists of lubricant base oil(A) having kinematic viscosity of 3.7~4.1mm^2/s at 100 deg.C and consisting of lubricant base oil having kinematic viscosity of 2.5~4.5mm^2/s at 100 deg.C and lubricant base oil having kinematic viscosity of 10~40mm^2/s at 100 deg.C; a poly(metha)acrylate viscosity index improver of 1~20wt.% having weight average molecular weight of 15000~30000, to the total weight percent of the composition; an imide friction modifier of 2~4wt.% having a hydrocarbon group with 8~30 carbons; a phosphorous extreme pressure additive of 0.01~0.04wt.%; and an ashless dispersing agent of 0.01~0.04wt.% having at least one of alkyl and alkenyl groups with number average molecular weight over 2000. The lubricant composition has kinematic viscosity of 5.6~5.8mm^2/s at 100 deg.C.

Description

Lubricant composition for automatic transmission {LUBRICANT COMPOSITIONS FOR AN AUTOMATIC TRANSMISSION}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition for an automatic transmission, and in particular, it has a low viscosity and a long fatigue life, and has excellent balance of durability against rudder prevention holding performance, low temperature viscosity characteristics, oxidation stability and friction characteristics, and particularly as for automobiles. A useful lubricant composition for an automatic transmission is.

In response to environmental problems such as the reduction of carbon dioxide emissions, the reduction of energy consumption, that is, fuel economy, has become an urgent task, and the contribution to energy saving is strongly required for engines and automatic transmissions. Therefore, the lubricating oil used for these is conventionally required to reduce stirring resistance and frictional resistance.

The low viscosity of lubricating oil is mentioned as one of the fuel economy saving means of an automatic transmission. For example, an automatic transmission for an automobile includes a torque converter, a wet clutch, a gear bearing mechanism, an oil pump, and a hydraulic control mechanism, and by lowering the lubricating oil used therein, the stirring resistance and the frictional resistance are reduced and the power transmission. By improving the efficiency, it is possible to improve the fuel economy of the vehicle.

However, lowering the viscosity of the lubricants used therein greatly reduces the fatigue life, burns, and the like, which may cause problems with the transmission. In particular, when a phosphorus extreme pressure agent is blended in order to improve the extreme pressure of low viscosity oil, fatigue life is remarkably deteriorated, so it is generally difficult to reduce the viscosity. In addition, sulfur-based extreme pressure agent can improve the fatigue life of the lubricating oil, the oxidative stability is deteriorated and a large amount of antioxidant is required.

Conventional automotive transmission flow paths can maintain various performances such as shifting characteristics for a long time, and include, for example, synthetic oils and / or mineral oil-based lubricant base oils, antiwear agents, extreme pressure agents, metal cleaners, ashless dispersants, friction modifiers, and viscosity indexes. It has been reported to optimize and formulate an enhancer (Japanese Patent Laid-Open No. 3-39399, Japanese Patent Laid-Open No. 7-268375, Japanese Patent Laid-Open No. 2000-63869, and Japanese Patent Laid-Open No. 2001-262176). Reference).

However, since these compositions are not all aimed at improving fuel economy, their kinematic viscosity is high, and no influence on fatigue life when the lubricant is low in viscosity has not been studied at all. Therefore, the composition which can solve such a subject has not been examined enough until now. Recently, for example, automatic transmission oils having a low viscosity of lubricating oil have been proposed (see Japanese Patent Application Laid-Open No. 2004-169025, Japanese Patent Application Laid-Open No. 2004-155924, Japanese Patent Application Laid-Open No. 2004-155873). However, although all have excellent anti-shudder retention performance, low temperature viscosity characteristics and oxidative stability, there is still room for improvement in order to achieve a balance of excellent durability and fuel economy of friction characteristics and fatigue resistance of gears.

SUMMARY OF THE INVENTION The object of the present invention is to provide a lubricant composition for automatic transmissions, particularly for automatic transmissions, which is excellent in rudder prevention holding performance, low temperature viscosity characteristics and oxidative stability, and has excellent balance of durability and fuel economy and frictional fatigue life of the friction characteristics. In addition, the present invention provides a lubricating oil composition for an automatic transmission that combines fuel efficiency reduction performance and fatigue life of a gear.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors discovered that the low viscosity automatic transmission lubricating oil composition which combined the specific base oil and the specific additive could solve the said subject, and came to complete this invention.

According to the present invention, (A1) at 100 ° C, consisting of lubricating oil base oil having a kinematic viscosity at 100 ° C of 2.5 to 4.5 mm ² / s and (A2) lubricating oil base oil having a kinematic viscosity at 100 ° C of 10 to 40 mm ² / s It can be abbreviated as lubricating oil base oil (A) having a kinematic viscosity of 3.7 to 4.1 mm ² / s and (B) a poly (meth) acrylate-based viscosity index improver having a weight average molecular weight of 15000 to 30000 (hereinafter, (B) component). ) 1 to 20% by mass based on the total amount of the composition, and (C) an imide-based friction modifier (hereinafter, abbreviated to (C) component) having a hydrocarbon group having 8 to 30 carbon atoms (2) to 4% by mass based on the total amount of the composition. % And (D) phosphorus extreme pressure agent (hereinafter may be abbreviated as (D) component) based on the total amount of the composition, 0.01 to 0.04% by mass, and (E) alkyl or alkenyl groups having a number average molecular weight of 2000 or more. Nitrogen content based on the whole quantity of the ashless dispersing agent (henceforth abbreviated as (E) component) which has at least one As a lubricating oil composition (hereinafter, abbreviated to the composition of the present invention) for an automatic transmission, there is provided a lubricating oil composition containing 0.01 to 0.04 mass% and having a kinematic viscosity at 100 ° C of 5.6 to 5.8 mm ² / s.

The composition of the present invention has a long fatigue life even at low viscosity, excellent anti-shudder holding performance, low temperature viscosity characteristics and oxidative stability, and excellent balance of durability and fuel economy of friction characteristics and fatigue life of gears, especially in automotive automatic transmissions. Fuel efficiency savings for cars can be achieved by combining proper fuel economy and fatigue life of gears.

Hereinafter, the present invention will be described in more detail.

The composition of this invention contains the specific lubricating oil base oil (A) and specific (B)-(E) component in a balanced manner, and made the kinematic viscosity in 100 degreeC into the range of 5.6-5.8 mm <^2> / s.

The composition of the present invention has a specific composition, and by setting the kinematic viscosity to the above-mentioned specific range, even if the composition is low viscosity, the fatigue life of the gear is long, and the durability of the rudder prevention holding performance, low temperature viscosity characteristic, oxidation stability and friction characteristics are all well balanced. can do.

If the kinematic viscosity is in excess of 5.8mm ² / s at 100 ℃ of the present composition it has not obtained sufficient fuel efficiency performance or excellent low temperature viscosity characteristics of the stirring resistance reduction, while the dynamic viscosity is 5.6mm ² / s under The fatigue life of the gear cannot be sufficiently extended.

In the present invention, the lubricating oil base oil (A) is a lubricating oil base oil having a kinematic viscosity of 2.5 to 4.5 mm ² / s (hereinafter, abbreviated to (A1) component) at 100 ° C (A1), that is, having this specific kinematic viscosity, One or two or more (A1) lubricating oil base oils selected from the group consisting of mineral oil base oils and synthetic oil base oils, and (A2) lubricating oil base oils having a kinematic viscosity of 10 to 40 mm ² / s at 100 ° C (hereinafter, (A2) Components may be abbreviated).

In the component (A1), the mineral oil base oil is, for example, solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and the like. Mineral oil base oils, such as a paraffin type and a naphthenic type refine | purified individually or in combination of 2 or more appropriately, such as a clay treatment, and normal paraffin, isoparaffin are mentioned. In addition, these base oils may be individual and may be used in combination of 2 or more types in arbitrary ratios.

Preferred mineral oil base oils include the following base oils.

(1) Oil spilled by atmospheric distillation of paraffin crude and / or mixed crude

(2) vacuum distillation distillate (WVGO) of atmospheric distillation residue of paraffin machine crude oil and / or mixed machine crude oil,

(3) Fischer-Trop's wax produced by wax and / or GTL process obtained by lubricating oil desoldering process,

(4) Mild hydrocracking process oil (MHC) of 1 type, or 2 or more types of mixed oil chosen from said (1)-(3),

(5) a mixed oil of two or more kinds of oils selected from the above (1) to (4),

(6) deasphaltene oil (DAO) of (1), (2), (3), (4) or (5),

(7) the mild hydrocracking oil (MHC) of (6),

(8) A mixed oil or the like of two or more kinds of oils selected from the above (1) to (7) is used as the raw material oil, and the raw oil and / or the lubricating oil fraction recovered from the raw material oil are purified by a conventional purification method. Lubricating oil obtained by recovering lubricating oil fraction.

The normal refining method referred to here is not particularly limited, and a refining method used at the time of producing a lubricant base oil can be arbitrarily employed. Typical refining methods include, for example, (a) hydrogenation purification such as hydrocracking and hydrogenation finish, (b) solvent purification such as furfural solvent extraction, (c) dewaxing such as solvent desorption and contact desorption, and (d) acidity. And chemical (acid or alkali) tablets such as white clay tablets using clay, activated clay, and (e) sulfuric acid washing and caustic soda washing. In the present invention, these purification methods may be employed alone, or two or more may be employed in any combination and in any order.

As the mineral oil base oil, a base oil obtained by further treating the base oil selected from the above (1) to (8) with the following treatment may be particularly preferably used.

In other words, the lubricating oil fraction recovered from the base oil selected from the above (1) to (8) is hydrocracked or wax isomerized, and the lubricating oil fraction is recovered as it is or from the product, and then desoldering such as solvent dewaxing or contact dewaxing. The hydrocracked mineral oil and / or the wax isomerized isoparaffinic base oil manufactured by carrying out the treatment, after which the solvent purification treatment or the solvent retention treatment are performed, and then the dewaxing treatment such as solvent dewaxing or contact dewaxing are preferably used. The hydrocracked mineral oil and / or wax isomerized isoparaffin base oil is preferably 30% by mass or more, more preferably 50% by mass or more, particularly preferably 70% by mass or more, based on the total amount of the mineral oil base oil.

In the component (A1), the synthetic oil base oil may be, for example, a poly alpha -olefin or a hydride thereof, isobutene oligomer or a hydride thereof, isoparaffin, alkylbenzene, alkylnaphthalene; Diesters such as ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, and di-2-ethylhexyl sebacate; Polyol esters such as trimethylol propane capryrate, trimethylol propane peragonate, pentaerythritol 2-ethylhexanoate and pentaerythritol ferragonate; Polyoxyalkylene glycol, dialkyl diphenyl ether, polyphenyl ether, etc. are mentioned.

Of the synthetic oil base oils, for example, the use of poly alpha -olefins or hydrides thereof is preferable. Examples of the poly α-olefins include oligomers or cooligomers of α-olefins having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms, and specifically 1-octene oligomers, 1-decene oligomers, and ethylene-propylene. Co oligomer etc., and its hydride are mentioned.

There is no restriction | limiting in particular in the manufacturing method of a poly-olefin, For example, aluminum trichloride, boron trifluoride, a boron trifluoride, water; And polymerization of α-olefins in the presence of a polymerization catalyst such as a Friedel-Crafts catalyst including a complex with an alcohol such as ethanol, propanol, butanol, carboxylic acid or ester such as ethyl acetate, ethyl propionate.

(A1) component should just contain at least 1 type of mineral oil base or synthetic base oil, For example, 2 or more types of mineral oil base oils, 2 or more types of synthetic oil base oils, a mixture thereof, and at least 1 type of mineral oil base oils, Mixture with at least one synthetic oil base oil is not a problem. In the case where the component (A1) is a mixture, the mixing ratio can be arbitrarily selected if the kinematic viscosity at 100 ° C of each base oil is 2.5 to 4.5 mm ² / s.

As (A1) component, 1 type, or 2 or more types chosen from the base oil of the following (A1a)-(A1c) are mentioned preferably.

(A1a) mineral oil base oil having a kinematic viscosity at 100 ° C. of 2.5 to 3.5 mm ² / s, preferably 2.5 to 3.2 mm ² / s,

(A1b) mineral oil base oil having a kinematic viscosity at 100 ° C of 3.5 to 4.5 mm ² / s, preferably 3.8 to 4.3 mm ² / s,

(A1c) Poly (alpha) -olefin base oil whose kinematic viscosity in 100 degreeC is 2.5-4.5 mm <^2> / s, Preferably it is 3.8-4.3 mm <^2> / s.

(A1)% C _A is not particularly limited in the components of the base oil such as of (A1a) ~ (A1c), but is, of 3 or less are preferred, and 2 or less, more preferably, is 1 or less is particularly preferred. Component (A1), and further it is possible to obtain the excellent oxidation stability of the composition by making the% C _A lubricating oil base oil (A) to 3 or less.

In the present invention,% C _A represents the percentage of the total carbon number of the aromatic carbon number determined by the method according to ASTM D 3238-85.

In (A1) components, such as base oil of (A1a)-(A1c), there is no restriction | limiting in particular in the viscosity index, Preferably it is 80 or more, More preferably, it is 90 or more, Especially preferably, it is 110 or more, Usually 200 Hereinafter, More preferably, it is 160 or less. By setting the viscosity index to 80 or higher, a composition exhibiting good viscosity characteristics from low to high temperatures can be obtained. If the viscosity index is too high, the effect on fatigue life is reduced.

The component (A1), such as the base oil of (A1a) to (A1c), is not particularly limited in its sulfur content, but is 0.05 mass% or less, in particular 0.02 mass% or less, further 0.005 mass% or less, based on the total amount of the component (A1). It is desirable to. The composition which is more excellent in oxidative stability can be obtained by reducing the sulfur content of (A1) component.

The base oils of (A1a) to (A1c) may be used alone, respectively, but may be optionally mixed. Especially, it is preferable to use together the base oil of (A1a), the base oil of (A1b), and / or the base oil of (A1c). On the other hand, content of the base oil of (A1a) and / or the base oil of (A1c) when using together the base oil of (A1b) and the base oil of (A1c), Preferably it is 1-50 mass% on the basis of the lubricating oil base oil (A) whole quantity basis. More preferably, it is 3-20 mass%, More preferably, it is 5-15 mass%. In particular, by blending the component (A1c) about 5 to 15% by mass, a composition excellent in fatigue life, low temperature characteristics, and oxidation stability can be obtained at low cost and effectively.

In lubricating oil base oil (A), (A2) component is a component which further improves the fatigue life of a gear, etc., For example, 1 type, or 2 or more types selected from the base oils of the following (A2a)-(A2c) are mentioned. have.

(A2a) Mineral oil and / or synthetic base oils having a kinematic viscosity at 100 ° C. of 10 to 15 mm ² / s, preferably 10 to 12 mm ² / s, preferably mineral oil base oils,

(A2b) a kinematic viscosity at 100 ℃ 15~25mm ² / s, preferably 17~23mm ² / s of mineral and / or synthetic base oils, preferably mineral base oils,

(A2c) a kinematic viscosity at 100 ℃ 25~40mm ² / s, preferably 28~35mm ² / s of mineral and / or synthetic base oils, preferably mineral base oils.

(A2a) ~ is roneun% C _A of the (A2) component of a base oil such as of (A2c) is usually 0 to 40 but not particularly limited, is preferably 2 or more from the fatigue point to both the service life and oxidative stability, and 4+ More preferably, 6 or more are especially preferable, 15 or less are preferable, 10 or less are more preferable, 8 or less are especially preferable.

The component (A2) such as the base oil of (A2a) to (A2c) is not particularly limited in its viscosity index, but is preferably 80 or more, more preferably 90 or more, particularly preferably 95 or more, usually 200 or less, Preferably it is 120 or less, More preferably, it is 110 or less, Especially preferably, it is 100 or less. By setting the viscosity index to 80 or more, a composition exhibiting good viscosity characteristics from low to high temperatures can be obtained. If the viscosity index is too high, the effect on fatigue life is lowered.

The component (A2), such as the base oil of (A2a) to (A2c), is not particularly limited in its sulfur content, but is usually 0 to 2% by mass, preferably 0.05 to 1.5% by mass, more preferably based on the total amount of the component (A2). Preferably it is 0.3-1.2 mass%, More preferably, it is 0.5-1 mass%, Especially preferably, it is 0.7-1.0 mass%. The fatigue life can be improved by using the thing with relatively high sulfur content as (A2) component, Preferably the composition which is more excellent in oxidative stability can be obtained by using 1.0 mass% or less.

In this invention, use of the base oil of (A2b) or (A2c) as (A2) component is preferable at the point of fatigue life improvement, and using a base oil of (A2b) can make both fatigue life and oxidative stability compatible. Particularly preferred. Moreover, by using the base oil of (A1c) as (A1) component, the composition excellent in fatigue life, oxidative stability, and low temperature viscosity characteristic can be obtained.

Although the compounding quantity of (A1) and (A2) component in lubricating oil base oil (A) does not have a restriction | limiting in particular, Preferably it is 70-97 mass%, More preferably, 85 (A1) component on the basis of lubricating oil base oil (A) whole quantity. It is -95 mass%, Preferably it is 3-30 mass%, More preferably, it is 5-15 mass% of (A2) component.

Lubricant base oil (A) is a lubricating oil base oil containing the above-mentioned (A1) component and (A2) component, The kinematic viscosity in 100 degreeC is 3.7-4.1 mm <^2> / s, Preferably it is 3.9-4.1 mm <^2> / s. . By setting the kinematic viscosity at 100 ° C to 4.1 mm ² / s or less, the fluid resistance is reduced, so that it is possible to obtain a lubricating oil composition having a smaller frictional resistance at the lubrication point. For example, the Brookfield viscosity at -40 ° C is 15000 mPa. It can be set as the composition excellent in the low temperature viscosity which is s or less. Further, by setting the kinematic viscosity at 100 ° C to 3.7 mm ² / s or more, oil film formation is sufficient, lubricity and fatigue life are more excellent, and it is possible to obtain a lubricating oil composition having a lower evaporation loss of base oil under high temperature conditions.

The% C _A of the lubricating oil base oil (A) is not particularly limited but is preferably 3 or less, more preferably 2 or less, particularly preferably 1 or less, preferably 0.1 or more, and even more preferably 0.5 or more. By the% C _A of the lubricating oil base oil (A) to 3 or less can be obtained with excellent oxidation stability and composition.

The lubricant base oil (A) is not particularly limited in its viscosity index, but is preferably 80 or more, more preferably 90 or more, and particularly preferably 110 or more. By making a viscosity index 80 or more, the composition which shows favorable viscosity characteristics from low temperature to high temperature can be obtained.

The lubricant base oil (A) is not particularly limited in its sulfur content, but is preferably 0 to 0.3 mass%, more preferably 0.03 to 0.2 mass%, particularly preferably 0.06 to 0.1 mass%. By setting the sulfur content of the lubricating oil base oil (A) to the above range, in particular, 0.03 to 0.2 mass%, both fatigue life and oxidative stability can be achieved.

In the composition of the present invention, the component (B) is a poly (meth) acrylate-based viscosity index improver having a weight average molecular weight of 15000 to 30000, and a viscosity-index improver obtained by diluting a poly (meth) acrylate-based compound with a diluent. . The weight average molecular weight of this poly (meth) acrylate-based compound is preferably 17000 to 25000, particularly preferably 18000 to 24000 from the viewpoint of more excellent fatigue life improvement effect.

Here, the weight average molecular weight uses two columns of GMHHR-M (7.8 mm ID x 30 cm) manufactured by Toso (TOSO) in a 150-C ALC / GPC device manufactured by Waters, and uses tetrahydrofuran, It means the weight average molecular weight of polystyrene conversion measured by the temperature of 23 degreeC, flow rate 1 mL / min, sample concentration 1 mass%, sample injection amount 75 microliters, and a detector differential refractive index (RI).

As a poly (meth) acrylate of the poly (meth) acrylate type compound which comprises (B) component, the poly (meth) acrylate which has a structural unit represented by Formula (1) is mentioned suitably.

In Formula (1), R <^1> is a hydrogen atom or a methyl group, Preferably methyl group, R <^2> represents a C1-C30 hydrocarbon group or group represented by-(R) aE. R represents an alkylene group having 1 to 30 carbon atoms, E represents an amine residue or heterocyclic residue containing 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms, and a represents 0 or 1.

Examples of the alkyl group having 1 to 30 carbon atoms represented by R ² include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group And tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, isocyl group, docosyl group, tetracosyl group, hexacosyl group and octacosyl group. These alkyl groups may be linear or branched.

Examples of the alkylene group having 1 to 30 carbon atoms represented by R include methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group and dode A silane group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, and an octadecylene group can be illustrated. These alkylene groups may be linear or branched.

Examples of the amine residue represented by E include dimethylamino group, diethylamino group, dipropylamino group, dibutylamino group, anilino group, toludino group, Xylidino group, acetylamino group and benzoylamino group. As the heterocyclic moiety represented by E, a morpholino group, a pyrrolyl group, a pyrrolino group, a pyridyl group, a methylpyridyl group, a pyrrolidinyl group, a piperidinyl group, a quinonyl group, a pyrrolidoneyl group, a pyrrolidone group, and an imida A jolino group and a pyradino group can be illustrated.

As a poly (meth) acrylate which has a structural unit represented by Formula (1), the poly (meth) acrylate obtained by superposing | polymerizing or copolymerizing 1 type, or 2 or more types of the monomer represented by Formula (1a) is mentioned. .

In the formula (1a), R ¹ and R ² are the same as R ¹ and R ² in the formula (1).

As a monomer represented by Formula (1a), (Ba)-(Be) monomer is mentioned, for example.

The (Ba) monomer is a (meth) acrylate having an alkyl group having 1 to 4 carbon atoms. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n- or i-propyl (meth) acrylate, n-, i-, or sec-butyl (meth) acrylate can be mentioned, Methyl (Meth) acrylate is preferable.

The monomer (Bb) is a (meth) acrylate having an alkyl group or alkenyl group having 5 to 15 carbon atoms. Specifically, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetra Decyl (meth) acrylate, pentadecyl (meth) acrylate, octenyl (meth) acrylate, nonenyl (meth) acrylate, decenyl (meth) acrylate, undecenyl (meth) acrylate, dodecenyl ( Meta) acrylate, tridecenyl (meth) acrylate, tetradecenyl (meth) acrylate, and pentadecenyl (meth) acrylate. They may be straight chain or branched. In particular, the (meth) acrylate which has a C12-15 linear alkyl group as a main component is mentioned preferably.

The monomer (Bc) is a (meth) acrylate having a straight chain alkyl group or alkenyl group having 16 to 30 carbon atoms, preferably a straight chain alkyl group having 16 to 20 carbon atoms, more preferably a straight chain alkyl group having 16 to 18 carbon atoms It is (meth) acrylate which has. Specifically, n-hexadecyl (meth) acrylate, n-octadecyl (meth) acrylate, n-icosyl (meth) acrylate, n-docosyl (meth) acrylate, n-tetracosyl (meth) ) Acrylate, n-hexacosyl (meth) acrylate, n-octacosyl (meth) acrylate, etc., and especially n-hexadecyl (meth) acrylate and n-octadecyl (meth) acrylate are mentioned. Preferred is mentioned.

The monomer (Bd) is a (meth) acrylate having a branched alkyl group or alkenyl group having 16 to 30 carbon atoms, preferably a branched alkyl group having 20 to 28 carbon atoms, more preferably a branched alkyl group having 22 to 26 carbon atoms It is (meth) acrylate which has. Specifically, branched hexadecyl (meth) acrylate, branched octadecyl (meth) acrylate, branched icosyl (meth) acrylate, branched docosyl (meth) acrylate, branched tetracosyl (meth) acrylate, branched Hexacosyl (meth) acrylate and branched octacosyl (meth) acrylate are mentioned. (Meth) acrylates having a branched alkyl group having 16 to 30 carbon atoms, preferably 20 to 28 carbon atoms, more preferably 22 to 26 carbon atoms, preferably represented by -CC (R ³ ) R ⁴ Can be. Herein, R ³ and R ⁴ are not limited at all if the carbon number of -CC (R ³ ) R ⁴ is 16 to 30, but R ³ is preferably 6 to 12 carbon atoms, more preferably 10 to 12 carbon atoms. A linear alkyl group is mentioned, As R <^4> , Preferably, C10-C16, More preferably, C14-C16 linear alkyl group is mentioned.

More specific examples of the (Bd) monomers include carbon such as 2-decyl-tetradecyl (meth) acrylate, 2-dodecyl-hexadecyl (meth) acrylate, and 2-decyl-tetradecyloxyethyl (meth) acrylate. (Meth) acrylate which has a number 20-30 branched alkyl group is mentioned.

(Be) monomers are polar group-containing monomers, for example, amide group-containing vinyl monomers, nitro group-containing monomers, primary to tertiary amino group-containing vinyl monomers, nitrogen-containing heterocycle-containing vinyl monomers, and hydrochlorides, sulfates, phosphates, and carbons thereof. Lower alkyl monocarboxylates such as numbers 1 to 8, quaternary ammonium base-containing vinyl monomers, amphoteric vinyl monomers containing oxygen and nitrogen, nitrile group-containing monomers, aliphatic hydrocarbon-based vinyl monomers, and alicyclic carbonization Hydrogen-based vinyl monomer, aromatic hydrocarbon-based vinyl monomer, vinyl ester, vinyl ether, vinyl ketone, epoxy group-containing vinyl monomer, halogen element-containing vinyl monomer, ester of unsaturated polycarboxylic acid, hydroxyl group-containing vinyl monomer, polyoxyalkyl Vinyl monomers containing a benzene chain-containing vinyl monomer, anionic group, phosphoric acid group, sulfonic acid group, or sulfate ester group; and Of a 1 there may be mentioned metal salts, such as divalent metal salts, amine salts or ammonium salts.

Among these, as the (Be) monomer, a nitrogen-containing monomer is preferable, and for example, 4-diphenylamine (meth) acrylamide, 2-diphenylamine (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, di Ethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylic The rate, morpholinomethyl methacrylate, morpholinoethyl methacrylate, 2-vinyl-5-methylpyridine, and N-vinylpyrrolidone are mentioned.

In the present invention, as the component (B), a viscosity index including a poly (meth) acrylate compound obtained by polymerizing or copolymerizing one or two or more kinds of monomers selected from the above-mentioned (Ba) to (Be) monomers. It is preferable that it is an improver.

More preferred examples of such a poly (meth) acrylate-based compound include 1) a non-dispersed poly (meth) acrylate or a hydride thereof which is a copolymer of (Ba) and (Bb) monomers, and 2) (Ba), (Bb). ) And (Bc) a non-dispersion type poly (meth) acrylate which is a copolymer of monomer, or its hydride, and 3) (Ba), (Bb), (Bc) and (Bd) monomer which is a non-dispersion type poly (meth) acryl Dispersible poly (meth) acrylates or hydrides thereof, which are copolymers of rate or hydrides thereof, 4) (Ba), (Bb) and (Be) monomers, 5) (Ba), (Bb), (Bc) and Dispersible poly (meth) acrylate which is a copolymer of (Be) monomer or its hydride 6) Dispersible poly (meth) which is a copolymer of (Ba), (Bb), (Bc), (Bd) and (Be) monomer Acrylate or its hydride, The non-dispersion type poly (meth) acrylate type compound of said 1) -3) is more preferable, The non-dispersion type poly of said 2) or 3) (Meth) acrylate type compounds are more preferable, and the non-dispersion type poly (meth) acrylate type compound of said 3) is especially preferable.

In the composition of the present invention, the component (B) is typically provided in a state in which the poly (meth) acrylate compound is diluted to about 10 to 80% by mass with a diluent in consideration of solubility in handling or lubricating oil base oil (A). Therefore, the compounding quantity is 1-20 mass%, Preferably it is 2-12 mass%, Especially preferably, it is 3-8 mass% as a compounding quantity which contains a diluent.

When the blending amount of component (B) exceeds the above range, not only the fatigue life improvement effect corresponding to the blending amount can be expected, but also the shear stability is poor, it is difficult to maintain the initial extreme pressure for a long time, and the fuel efficiency due to low viscosity There is a risk that the savings will be small.

The compounding quantity of (B) component suitably so that the kinematic viscosity in 100 degreeC of the composition of this invention may be 5.6-5.8 mm <^2> / s from within the said range according to the kind of the said poly (meth) acrylate type compound, and the ratio of a diluent. You can choose to decide.

In the composition of this invention, (C) component is an imide type friction modifier which has a C8-C30 hydrocarbon group.

The component (C) is not particularly limited as long as it is a compound having a hydrocarbon group and an imide structure having 8 to 30 carbon atoms, but for example, succinic acid imide represented by the formula (2) or (3) and / or its derivatives. Is preferred.

In formula (2), R <^5> is a C8-C30 linear or branched hydrocarbon group, R <^6> is a hydrogen atom or a C1-C30 linear or branched hydrocarbon group, R <^7> is carbon The number 1-4 hydrocarbon group is shown. m is an integer of 1-7.

In formula (3), R <^8> and R <^9> respectively independently represents a C8-C30 linear or branched hydrocarbon group, R <^10> and R <^11> represent a C1-C4 hydrocarbon group, respectively . n is an integer of 1-7.

R <^5> of Formula (2), R <^8>, and R <^9> of Formula (3) respectively independently represent a C8-C30, preferably C12-C25 linear or branched hydrocarbon group. Examples of such hydrocarbon groups include alkyl groups and alkenyl groups, with alkyl groups being preferred. Examples of the alkyl group and the alkenyl group include, but are not limited to, octyl, octenyl, nonyl, nonenyl, decyl, decenyl, dodecyl, dodecenyl, octadecyl, and octadecenyl groups. And a chain or branched alkyl group. When the carbon number of the hydrocarbon group is less than 8 and exceeds 30, it is difficult to obtain a sufficient shielding vibration preventing effect. In particular, it is preferable that it is a C8-C30 branched alkyl group, Furthermore, it is a C10-C25 branched alkyl group. In the case of a branched alkyl group having 8 to 30 carbon atoms, the reduction in torque capacity in various wet clutches is smaller than that in the case of using a linear alkyl group, whereby a composition excellent in both the torque capacity and the rudder prevention performance retention characteristics can be obtained.

R ^{7 in} formula (2) And R ¹⁰ of formula (3) And R ¹¹ each independently represent a hydrocarbon group having 1 to 4 carbon atoms. As this hydrocarbon group, a C1-C4 alkylene group etc. are mentioned, Preferably, C2-C3 alkylene groups, such as an ethylene group and a propylene group, are mentioned.

As R <^6> of Formula (2), a C1-C30 linear or branched alkyl group or alkenyl group is mentioned, for example, Preferably it is C1-C30, More preferably, it is C8-C30, Especially preferably, a C10-C25 branched alkyl group or alkenyl group is mentioned, A branched alkyl group is especially preferable.

In formula (2) or (3), n and m represent the integer of 1-7, respectively, and n and m are preferably 1, 2 or 3, respectively, in order to obtain a composition with higher rudder prevention performance retention property, Especially preferably, it is 1, respectively.

The succinic acid imide compound represented by formula (2) or (3) can be manufactured by a well-known method. For example, it can be obtained by reacting an alkyl or alkenyl succinic anhydride with a polyamine. Specifically, in the monosuccinic acid imide represented by Formula (2) in which R ⁶ is a hydrogen atom, for example, carbon is used with respect to 1 mole or more of polyamines such as diethylenetriamine, triethylenetetramine or tetraethylenepentamine. 1 mol of succinic anhydrides having 8 to 30 linear or branched alkyl or alkenyl groups are slowly added dropwise at a temperature of 130 to 180 ° C, preferably 140 to 175 ° C under a nitrogen atmosphere, preferably 1 to 10 hours. Can be obtained by reacting for 2 to 6 hours and distilling off unreacted polyamine. In addition, in the monosuccinic acid imide represented by Formula (2) wherein R ⁶ is a C 1-30 hydrocarbon group, for example, N-octadecyl-1,3-propanediamine and the succinic anhydride are the same methods as described above. It can obtain by making it react. In addition, also in the bissuccinic acid imide represented by Formula (3), 0.5 mol of such polyamines are dripped on the same conditions as the above with respect to 1 mol of said succinic anhydrides, and it is obtained by making it react similarly, and removing the water | moisture content produced. Can be.

As a derivative of the succinic acid imide represented by Formula (2) or (3), the compound which modified | denatured this succinic acid imide by boric acid, phosphoric acid, carboxylic acid, these derivatives, a sulfur compound, triazoles, etc. is mentioned. As a specific example and manufacturing method of this derivative, the compound, the method, etc. which are specifically described in Unexamined-Japanese-Patent No. 2002-105478 can be used.

In the present invention, since a composition having a higher resistance to shedding resistance can be obtained as compared with the mono-type succinic acid imide represented by the formula (2) as the component (C), the use of the bis-type succinic acid imide represented by the formula (3) This is particularly preferred.

In the composition of this invention, content of (C) component is 2-4 mass% on the basis of a composition whole quantity, Preferably it is 2.5-3.5 mass%. When the content of the component (C) is less than 2% by mass, it is difficult to reach the high target of the present invention, for example, the prevention of the protection against shedding, when the content of the component (C) is less than 1000 hours, while the content of the component (C) is 4% by mass. When it exceeds%, there exists a possibility that a fatigue life may worsen.

In the composition of the present invention, the component (D) is a phosphorus extreme pressure agent. Specifically, phosphoric acid monoesters, phosphoric acid diesters, phosphoric acid triesters, phosphorous acid monoesters, phosphorous acid diesters, phosphorous acid triesters having 3 to 30 carbon atoms, preferably 4 to 18 alkyl or aryl groups And salts of these esters with amines or alkanolamines. Especially, the phosphorus acid ester which has a C3-C30 alkyl group is preferable, and the phosphorous acid ester which especially has a C3-C30 alkyl group is preferable.

In the composition of the present invention, the content ratio of the component (D) is 0.01 to 0.04 mass%, preferably 0.02 to 0.04 mass%, based on the total amount of the composition. When the amount of the component (D) is less than the above range, there is a tendency that the rudder prevention performance maintainability tends to be inferior, and when the above-mentioned range is exceeded, the fatigue life tends to deteriorate.

In the composition of the present invention, the component (E) is an ashless dispersant having at least one alkyl group or alkenyl group having a number average molecular weight of 2000 or more.

Typical examples of the component (E) include a succinic acid-based ashless dispersant, a benzylamine ashless dispersant, a polyamine ashless dispersant and the like having at least one alkyl group or alkenyl group having a number average molecular weight of 2000 or higher. A succinic acid imide ashless dispersant having at least one group is preferable, and a bis-type succinic acid imide ashless dispersant having at least two alkyl groups or alkenyl groups is particularly preferable.

The number average molecular weight of this alkyl group or alkenyl group becomes like this. Preferably it is 2000-5000, More preferably, it is 2100-3500, More preferably, it is 2200-3000. The alkyl group or alkenyl group may be linear or branched. Preferably, an oligomer of an olefin such as propylene, 1-butene or isobutene, a branched alkyl group or a branched alken derived from an oligomer of ethylene and propylene And the like, and a polybutenyl group derived from poly (iso) butene is particularly preferable.

By setting the number average molecular weight of the alkyl group or alkenyl group to 2000 or more, it is possible to improve the anti-shudder performance, to improve the durability of the friction characteristics and the fatigue life of the gear, and to set it to 5000 or less to provide a composition having superior lower temperature characteristics. Easy to get

As a succinic acid imide which has at least one alkyl group or alkenyl group whose said number average molecular weight is 2000 or more, the compound represented by Formula (4-a) or (4-b) can be illustrated more specifically.

In the above formula, R ¹² , R ¹³ and R ¹⁴ each independently represent an alkyl group or alkenyl group having a number average molecular weight of 2000 or more, preferably 2000 to 5000, and more preferably a poly (iso) butenyl group. r is 1-5, Preferably the integer of 2-4 is represented. s represents the integer of 0-4, Preferably 1-3.

The said succinic acid imide is represented by the so-called mono type succinic acid imide represented by Formula (4-a) in which succinic anhydride is added to one end of polyamine, and the formula (4-b) in which succinic anhydride is added to both ends of polyamine. So-called bissuccinic acid imides are included, and in the composition of the present invention, only one of them may be included, or a mixture thereof may be included. Succinic imide is particularly preferred.

There is no restriction | limiting in particular in the manufacturing method of the said succinic acid imide, For example, poly (iso) butenyl succinic acid obtained by reacting polybutene or polyisobutylene of number average molecular weight 2000 or more with maleic anhydride at 100-200 degreeC is polyamine. It can be obtained by reacting with. Examples of the polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

As a benzylamine which has at least one alkyl group or alkenyl group whose number average molecular weight is 2000 or more, the compound represented by Formula (4-c) can be illustrated more specifically.

In the above formula, R ¹⁵ represents an alkyl or alkenyl group having a number average molecular weight of 2000 or more, preferably 2000 to 5000, more preferably a poly (iso) butenyl group, and t is 1 to 5, preferably 2 The integer of -4 is shown.

The manufacturing method of the benzylamine represented by Formula (4-c) is not limited at all, For example, after making polyolefin, such as a propylene oligomer, a polybutene, an ethylene-alpha-olefin copolymer, react with phenol to make alkylphenol, It can be obtained by reacting polyaldehyde, such as formaldehyde, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, by Mannich reaction or the like.

As a polyamine which has at least one alkyl group or alkenyl group whose number average molecular weight is 2000 or more, the compound represented by Formula (4-d) can be illustrated more specifically.

In the above formula, R ¹⁶ represents an alkyl or alkenyl group having a number average molecular weight of 2000 or more, preferably 2000 to 5000, more preferably a poly (iso) butenyl group, and q is 1 to 5, preferably 2 The integer of -4 is shown.

The manufacturing method of the polyamine represented by Formula (4-d) is not limited at all, For example, after chlorinating polyolefin, such as a propylene oligomer, a polybutene, and an ethylene-alpha-olefin copolymer, ammonia, ethylenediamine, and di It can obtain by making polyamine, such as ethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, react.

The component (E) also includes derivatives of nitrogen-containing compounds such as succinic acid imide, benzylamine and polyamine. Examples of the derivative include polycarboxylic acids having 2 to 30 carbon atoms, such as monocarboxylic acids such as fatty acids having 2 to 30 carbon atoms, oxalic acid, phthalic acid, trimellitic acid and pyromellitic acid, to the nitrogen-containing compounds described above. Acids or anhydrides thereof, or ester compounds, alkylene oxides having 2 to 6 carbon atoms, hydroxy (poly) oxyalkylene carbonates, and the like, to neutralize some or all of the remaining amino and / or imino groups So-called acid-modified compounds which have been or have been amidated; So-called rod-modified compounds in which boron compounds such as boric acid, borates or boric acid esters are reacted with nitrogen-containing compounds as described above, and neutralized or amidated some or all of the remaining amino and / or imino groups; Sulfur-modified compounds in which a sulfur compound is applied to a nitrogen-containing compound as described above; And modified compounds in which two or more kinds of modifications selected from acid modification, boron modification, and sulfur modification are combined with the nitrogen-containing compound as described above.

Since the boron modified compound of the alkyl or alkenyl succinic acid imide whose number average molecular weight is 2000 or more among the said derivatives has the best fatigue prevention performance in gear, it is especially preferable to contain the said boron modified compound necessarily.

In the boron-modified compound of the nitrogen-containing compound, the mass ratio (B / N ratio) of boron and nitrogen is not particularly limited, but is preferably 0.1 or more, more preferably 0.2 or more, and preferably 0.6 or less, more preferably Is 0.3 or less. By selecting the B / N ratio of the boron-modified compound in the above range, a composition excellent in fatigue prevention performance in a gear can be obtained.

Although nitrogen content contained in (E) component is arbitrary, it is 0.01-10 mass% normally from the point of abrasion resistance, oxidative stability, friction characteristics, etc., Preferably it is 0.1-3 mass%, Especially preferably, it is 0.2- 1 mass%.

In the composition of the present invention, the lower limit of the content of the component (E) is 0.01% by mass or more, preferably 0.02% by mass or more, based on the total amount of the composition, while the upper limit of the content is 0.04% by mass, based on the total amount of the composition. % Or less, preferably 0.035 mass% or less.

When content of (E) component is less than 0.01 mass%, it is difficult to maintain durability of a friction characteristic and torque capacity, and there exists a tendency for oxidative stability to worsen. Moreover, even if it exceeds 0.04 mass%, since the effect equivalent to a compounding quantity is small, and the low temperature fluidity | liquidity of the composition of this invention and the fatigue prevention performance in a gear deteriorate, it is not preferable, respectively.

In the case where the boron-modified compound of the nitrogen-containing compound is essentially contained as the component (E), the lower limit of the content thereof is 0.003% by mass or more, preferably 0.004% by mass or more as boron based on the total amount of the composition, and the upper limit of the content. The amount of boron is 0.01% by mass or less, preferably 0.008% by mass or less, based on the total amount of the silver composition.

By setting the boron-modified compound as the amount of boron in the above-mentioned preferred range as the component (E), the durability, torque capacity, low temperature fluidity and gear fatigue prevention performance of the friction characteristics can be maintained in a highly balanced manner.

In order to obtain the outstanding viscosity-temperature characteristic of the composition of this invention, it is preferable to make the viscosity index of a composition into 95-200, More preferably, it is 150-180. Moreover, 25-30 mm <^2> / s is suitable for the kinematic viscosity in 40 degreeC of a composition.

In order to further improve the performance of the composition of the present invention, or to impart the necessary performance to the lubricant for automatic transmission, a polarity other than the viscosity index improver, the friction regulator other than the component (C), and the component (D) as necessary. Various additives such as dispersant, dispersant other than component (E), metal detergent, antioxidant, corrosion inhibitor, rust preventive agent, anti-emulsifier, metal deactivator, pour point depressant, sealing swelling agent, antifoaming agent, colorant, etc. alone or in combination It can also mix | blend.

As the viscosity index improver, known non-dispersed or dispersed polymethacrylates (except component (B)), non-dispersed or dispersed ethylene-α-olefin copolymers or hydrides thereof, polyisobutylene or the like Hydrides, styrene-diene hydrogenated copolymers, styrene-maleic anhydride ester copolymers, polyalkylstyrenes, and the like.

When mix | blending viscosity index improvers other than (B) component with the composition of this invention, the compounding quantity does not have a restriction | limiting as long as it satisfy | fills the prescription | regulation of dynamic viscosity in 100 degreeC of a composition, Usually 0.1-15 mass%, Preferably it is 0.5-5 mass%.

As the friction modifier other than the component (C), any compound usually used as a friction modifier for lubricating oil can be used, for example, an alkyl group or alkenyl group having 6 to 30 carbon atoms, especially a straight chain alkyl group having 6 to 30 carbon atoms or a straight chain. Amine compounds having at least one alkenyl group in the molecule, fatty acids, fatty acid esters, fatty acid amides, fatty acid metal salts are preferably used.

In the present invention, one or two or more compounds arbitrarily selected from the friction modifiers may be contained in any amount. Content in the case of including it is 0.01-5.0 mass% normally on the basis of a composition whole quantity, Preferably it is 0.03-3.0 mass%.

As the extreme pressure agent other than the component (D), for example, at least one selected from the group consisting of sulfided fats and oils, sulfided olefins, dihydrocarbyl polysulfides, dithiocarbamates, thiadiazoles, and benzothiazoles, for example. Sulfur-based extreme pressure agents and / or thiophosphoric acid, thiophosphorous acid monoesters, thiophosphorous acid diesters, thiophosphorous acid triesters, dithiophosphoric acid, dithiophosphoric acid monoesters, dithiophosphoric acid diesters, dithiophosphoric acid Consisting of at least one phosphorus-sulfur extreme pressure agent selected from the group consisting of triesters, trithiophosphoric acid, trithiophosphoric acid monoesters, trithiophosphorous acid diesters, trithiophosphoric acid triesters, and salts thereof It is preferable to mix an extreme pressure agent.

When mix | blending extreme pressure agents other than (D) component with the composition of this invention, the compounding quantity can be suitably selected according to the kind.

As a dispersant other than the component (E), ashless dispersants (except the component (E)) such as succinic acid imide, benzylamine, polyamine and / or boron compound derivatives having a hydrocarbon group of 40 to 400 carbon atoms may be blended. Can be.

In the present invention, one or two or more compounds optionally selected from the above dispersants may be contained in any amount. Content in the case of including it is 0.01-15 mass% normally on the basis of composition whole quantity, Preferably it is 0.1-8 mass%.

Examples of the metal-based cleaning agent include metal-based cleaning agents such as alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates.

In this invention, 1 type (s) or 2 or more types of compounds arbitrarily selected from the said metal type cleaning agents can be contained in arbitrary amounts. Content in the case of including it is 0.01-10 mass% normally on the basis of composition whole quantity, Preferably it is 0.1-5 mass%.

As antioxidant, if it is generally used for lubricating oils, such as a phenolic compound and an amine compound, it can be used.

Specifically, alkylphenols such as 2,6-di-tert-butyl-4-methylphenol and bisphenols such as methylene-4,4-bisphenol (2,6-di-tert-butyl-4-methylphenol) , Naphthylamines such as phenyl-α-naphthylamine, dialkyldithiophosphates zinc such as dialkyldiphenylamines, di-2-ethylhexyldithio zinc phosphate, (3,5-di-tert-butyl 4-hydroxyphenyl) fatty acids (such as propionic acid) or (3-methyl-5-tert-butyl-4-hydroxyphenyl) fatty acids (such as propionic acid) and monohydric or polyhydric alcohols such as methanol, octanol, Ester with octadecanol, 1,6-hexadiol, neopentyl glycol, thiodiethylene glycol, triethylene glycol, pentaerythritol and the like.

One or two or more compounds optionally selected from these may contain any amount. Content in the case of including it is 0.01-5 mass% normally on the basis of composition whole quantity, Preferably it is 0.1-3 mass%.

As a corrosion inhibitor, a benzotriazole type, a tritriazole type, a thiadiazole type, or an imidazole type compound is mentioned, for example.

As a rust inhibitor, petroleum sulfonate, alkylbenzenesulfonate, dinonyl naphthalenesulfonate, alkenyl succinic acid ester, or polyhydric alcohol ester is mentioned, for example.

As an antiemulsifier, polyalkylene glycol type | system | group nonionic surfactant, such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, or polyoxyethylene alkyl naphthyl ether, is mentioned, for example.

Examples of metal deactivators include imidazolines, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazolepolysulfides, 1,3, 4-thiadiazolyl-2,5-bisdialkyldithiocarbamate, 2- (alkyldithio) benzoimidazole, or β- (o-carboxybenzylthio) propionnitrile.

As the pour point lowering agent, a known pour point lowering agent can be arbitrarily selected according to the lubricating oil base oil, and a polymethacrylate having a weight average molecular weight of preferably 20000 to 500000, more preferably 50000 to 300000, particularly preferably 80000 to 200000 desirable.

As the antifoaming agent, any compound usually used as an antifoaming agent for lubricating oil can be used. Examples thereof include silicones such as dimethylsilicone and fluorosilicone.

As a sealing swelling agent, arbitrary compounds normally used as a sealing swelling agent for lubricating oil can be used, For example, sealing swelling agents, such as ester type, sulfur type, and aromatic type, are mentioned.

As the colorant, any compound commonly used can be used, and any amount can be blended, but the amount is usually 0.001 to 1.0 mass% based on the total amount of the composition.

In the case where these additives are contained in the composition of the present invention, the content is 0.005 to 5% by mass in corrosion inhibitors, rust preventive agents and anti-emulsifiers, 0.005 to 2% by mass in pour point depressants and metal deactivators, respectively, based on the total amount of the composition. In the agent, it is usually selected in the range of 0.01 to 5% by mass and the defoamer to 0.0005 to 1% by mass.

Example

Hereinafter, although the content of this invention is demonstrated further more concretely by an Example and a comparative example, this invention is not limited to these at all.

Example  1 to 3, Comparative example  1 to 9

According to the composition shown in Table 1, the lubricating oil composition (Examples 1-3) for automatic transmission which concerns on this invention was prepared. The performance evaluation test shown below was done about these compositions. The results are shown in Table 1.

According to the composition shown in Table 1, the lubricating oil compositions for comparison (Comparative Examples 1-9) were prepared, and the same performance evaluation test was done also about these compositions. The results are also shown in Table 1.

[Shutter-proof maintenance performance]

In accordance with the "automatic transmission oil shedding prevention performance test method" defined in JASO M349-98, the oil temperature during the endurance test was subjected to a low-speed sliding test at 120 ° C, and the shedding prevention life of the compositions of Examples and Comparative Examples was evaluated. On the other hand, the life of the reference oil specified in the test method is 72 hours, and if it is equal to or more than that, it is judged that the anti-shutter life is excellent. The test was stopped.

Low Temperature Viscosity Measurement

The low temperature viscosity at -40 degreeC of the lubricating oil composition for transmissions was measured in the liquid bath low temperature tank based on the "method of low temperature viscosity test of gear oil" prescribed | regulated to JPI-5S-26-85. In this invention, although 15000 mPa * s or less was aimed, it turned out that it is preferable that it is 10000 mPa * s or more from the point which is excellent in fatigue life.

Oxidation Stability

The acid value increase (mgKOH / g) after the test oil was forcibly deteriorated in the ISOT test (150 degreeC, 96 hours) based on JISK2514 was measured.

[SAE No.2 overkill test]

The durability of the shift characteristics of the wet clutch in accordance with JASO M348-95 "Automatic Transmission Oil Friction Characteristics Test Method" was evaluated using a SAE No. 2 overkill tester except the following severe test conditions.

(Exam conditions)

Oil temperature: 120 ° C., rotation speed: 3000 rpm, inertial mass: 0.5 kg · m ² , surface pressure: 1.9 MPa.

On the other hand, the test only performs the movement friction test, and after rotating the clutch at 3000 rpm and an inertial mass of 0.5 kg · m ² without load, pressure is applied to press the clutch to stop the rotation. The friction coefficient was calculated from the torque generated at the relative rotational speed of 1200 rpm, and the clutch was summarized as the friction coefficient.

(Based on judgment)

For each composition, from the average of the coefficients of motion friction coefficient of 1 to 100 cycles, the number of cycles when the coefficient of motion friction decreased by 0.02 or more was regarded as the endurance life cycle. Finished.

[Practical Gear Fatigue Life Test]

The fatigue life (pitching life) of the reduction gear when a load was applied to the motoring device was evaluated using a commercial three-speed automatic transmission (AY2 unit) manufactured by Jatco Co., Ltd.

(Exam conditions)

Oil temperature: 120 ℃, rotation speed: 1000rpm, load torque: 422N (output shaft torque), gear: 1 speed fixed.

(Based on judgment)

Open inspection was carried out every 1 million cycles, and the number of cycles in which pitching occurred was made into life.

From Table 1, the lubricating oil composition for automatic transmission (Examples 1-3) which used the specific amount of (A) component-(E) component in this invention has long fatigue life even at low viscosity, and has no rudder prevention holding performance. It has excellent balance of low temperature viscosity and oxidative stability, and excellent balance of durability and fuel economy of friction characteristics and fatigue life of gear. On the other hand, when each component prescribed | regulated by this invention is not mix | blended balancedly, it turns out that either of the said performances is not enough (Comparative Examples 1-9).

The lubricating oil composition for an automatic transmission of the present invention is excellent in rudder prevention holding performance, low temperature viscosity characteristics and oxidative stability, and has excellent balance in both durability of friction characteristics, fuel economy reduction and fatigue life of gears. Moreover, it is particularly suitable for automotive automatic transmissions, which combines fuel efficiency and gear fatigue life.

Claims (1)

(A1) lubricating oil base oil having a kinematic viscosity of 2.5 to 4.5 mm ² / s at 100 ° C., and (A2) consisting of a lubricating oil base oil having a kinematic viscosity at 100 ° C of 10 to 40 mm ² / s, Lubricant base oil (A) having a kinematic viscosity of 3.7 to 4.1 mm ² / s at 100 ° C., (B) 1-20 mass% of poly (meth) acrylate type viscosity index improvers whose weight average molecular weights are 15000-30000, (C) 2-4 mass% of the imide system friction modifier which has a C8-C30 hydrocarbon group based on a composition whole quantity, (D) 0.01-0.04 mass% of phosphorus extreme pressure agent based on composition whole quantity, (E) 0.01 to 0.04% by mass of a ashless dispersant having at least one alkyl group or alkenyl group having a number average molecular weight of 2000 or more as a nitrogen content based on the total amount of the composition, The kinematic viscosity at 100 ° C is 5.6 to 5.8 mm ² / s.