JP6510954B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to lubricating oil compositions, in particular those suitable for automatic transmissions.

  A technology often applied in recent years as a fuel saving technology for driving system oil is to reduce the stirring loss by lowering the product viscosity. However, it is a well-known fact that the oil film thickness is reduced to lower the extreme pressure property and the wear resistance by reducing the viscosity of the product in order to save fuel consumption.

Unexamined-Japanese-Patent No. 2004-262979 Unexamined-Japanese-Patent No. 2006-117853

  In view of the above circumstances, the present invention ensures a clutch torque capacity while significantly reducing the coefficient of friction between metals in a wide temperature range in order to improve fuel economy, and is a lubricating oil composition excellent also in extreme pressure properties. Intended to provide.

  As a result of intensive studies on the above problems, the present inventors have found that a lubricating oil composition comprising a predetermined base oil in combination with a predetermined molybdenum compound, a thiophosphoric acid ester having a carboxy group and a metal detergent in a predetermined ratio The present invention has been completed.

（式（１）中、Ｒ_１は水素原子もしくは炭素数１〜２０のヒドロカルビル基、Ｒ_２は炭素数１〜２０のヒドロカルビル基、Ｒ_３は炭素数１〜８の２価のヒドロカルビル基を示す。） That is, the present invention has (A) a lubricating oil base oil having (B) a molybdenum compound in an amount of 20 to 1000 mass ppm based on the total amount of the molybdenum compound, (C) a carboxy group shown in the following formula (1) Containing 5 to 500 mass ppm of thiophosphoric acid ester based on the total amount of the composition, 10 to 1000 mass ppm based on the total amount of the composition of the (D) alkali metal and / or alkaline earth metal-based detergent A lubricating oil composition characterized by

(In formula (1), R ₁ represents a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, R ₂ represents a hydrocarbyl group having 1 to 20 carbon atoms, and R ₃ represents a bivalent hydrocarbyl group having 1 to 8 carbon atoms .)

  The present invention is also the lubricating oil composition as described above, wherein the component (D) is calcium sulfonate.

The present invention also relates to the lubricating oil composition as described above, wherein the lubricating oil base oil (A) has a% C _P of 60 or more, a% C _N of 40 or less, and a% C _A of 3 or less. is there.

The present invention is also the lubricating oil composition as described above, wherein the kinematic viscosity of the (A) lubricating base oil at 100 ° C. is 2.0 to 4.3 mm ² / s.

In the present invention, the kinematic viscosity of the lubricating oil composition at 40 ° C. is 4 to 25 mm ² / s, and the kinematic viscosity at 100 ° C. is 2.0 to 5.4 mm ² / s. It is a lubricating oil composition.

  The present invention is also the lubricating oil composition as described above, further comprising (E) a pour point depressant.

  Furthermore, the present invention is the lubricating oil composition as described above, characterized in that it is used in an automatic transmission.

  The lubricating oil composition of the present invention secures the clutch torque capacity while significantly reducing the coefficient of friction between metals at low temperature for efficiency improvement, is also excellent in extreme pressure property, and is an automatic transmission excellent in fuel saving and durability. It is a lubricating oil composition suitable for mechanical applications.

  Hereinafter, the present invention will be described in detail.

  The lubricating oil composition of the present invention contains a lubricating base oil as component (A).

  As a lubricant base oil, a base oil usually used as a lubricant base oil can be used. For example, mineral oil-based lubricating base oils, synthetic lubricating base oils and mixtures thereof can be mentioned.

  As a mineral oil-based lubricating base oil, the lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining Examples thereof include paraffinic and naphthenic mineral oil-based lubricating base oils, normal paraffins, isoparaffins and the like, which are purified by appropriately combining refining treatments such as sulfuric acid washing and white earth treatment. These base oils may be used alone or in combination of two or more at any ratio.

The following base oils can be mentioned as a preferable mineral oil type lubricating base oil.
[1] Distilled oil by atmospheric distillation of paraffin base crude oil and / or mixed base crude oil;
[2] Vacuum distillation distillate (WVGO) of paraffin-based crude oil and / or atmospheric distillation residual oil of mixed-based crude oil;
[3] Wax obtained by lubricating oil dewaxing step and / or Fischer-Tropsch wax produced by GTL process or the like;
Mild hydrocracking treated oil (MHC) of one or more mixed oils selected from [4] [1] to [3];
[5] A mixed oil of two or more oils selected from [1] to [4];
[6] [1], [2], [3], [4] or [5] deasphalted oil (DAO);
Mild hydrocracking oil (MHC) of [7] [6];
[8] A mixed oil of two or more oils selected from [1] to [7], etc. is used as a starting oil, and this starting oil and / or a lubricating oil fraction recovered from this starting oil are A lubricating oil obtained by refining according to a refining method and recovering a lubricating oil fraction

  The conventional refining method referred to here is not particularly limited, and the refining method used in the production of the lubricating base oil can be arbitrarily adopted. Examples of conventional purification methods include (a) hydrocracking such as hydrocracking and hydrofinishing, (b) solvent purification such as furfural solvent extraction, and (c) dewaxing such as solvent dewaxing or catalytic dewaxing. (D) Purification of clay by acid clay or activated clay or the like, (e) Chemical (acid or alkali) purification such as sulfuric acid washing, caustic soda washing, etc. In the present invention, one or more of these can be adopted in any combination and in any order.

As a mineral oil type lubricating oil base oil used by this invention, the base oil obtained by further performing the following processes to the base oil chosen from said [1]-[8] is especially preferable.
That is, the base oil selected from the above [1] to [8] as it is, or the lubricating oil fraction recovered from this base oil is hydrocracked or wax isomerized, and the product as it is or from this lubricating oil The fraction is recovered and then subjected to dewaxing treatment such as solvent dewaxing or catalytic dewaxing, and then subjected to solvent refining and / or hydrorefining treatment, or after solvent refining treatment and / or hydrorefining Hydrocracked mineral oils and / or wax-isomerized isoparaffinic base oils produced by dewaxing treatment such as solvent dewaxing and catalytic dewaxing are preferably used. The hydrocracked mineral oil and / or the wax isomerized isoparaffinic base oil is preferably used in an amount of 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 base oil.

  Examples of synthetic lubricating base oils include poly α-olefins (ethylene-propylene copolymers, polybutenes, 1-octene oligomers, 1-decene oligomers, hydrides thereof and the like), aromatics such as alkylbenzenes and alkylnaphthalenes Base oil, monoester (butyl stearate, octyl laurate), diester (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl cepacate etc.), polyester ( D) trimellitic acid esters, etc .; polyol esters (such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate etc.) Ether base oils such as tellurium base oils, polyoxyalkylene glycols, polyphenyl ethers and dialkyl diphenyl ethers, phosphoric esters (tricresyl phosphate etc.), fluorine-containing compounds (perfluoropolyethers, fluorinated polyolefins etc.), silicone Oil, high performance hydrocarbon base oil obtained by isomerization and hydrogenation of synthetic wax such as FT reaction and / or wax obtained from petroleum refining process (preferably slack wax obtained from solvent dewaxing process), terpenes The hydrocarbon base oil etc. which are obtained by hydrogenating such a naturally derived unsaturated hydrocarbon can be illustrated.

  Preferred synthetic lubricating base oils include poly alpha-olefins. As the poly α-olefin, typically, an oligomer or co-oligomer of an α-olefin having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms (eg, 1-octene oligomer, 1-decene oligomer, ethylene-propylene co-oligomer Etc.) and their hydrides.

  The lubricant base oil may be a mixture of two or more types of mineral oil-based base oils or a mixture of two or more types of synthetic oil-based base oils, and is a mixture of a mineral oil-based base oil and a synthetic oil-based base oil. It does not matter. And the mixing ratio of two or more types of base oils in the said mixture can be selected arbitrarily. In the present invention, the lubricant base oil is preferably a hydrocarbon base oil, and in particular, from the viewpoint of fuel saving, a hydrocracked mineral oil excellent in viscosity-temperature characteristics is more preferable, and a wax isomerized base oil is more preferable. .

% C _P of the lubricating base oil is not particularly limited but is preferably 60 or more, more preferably 65 or more, more preferably 70 or more.
% C _N of the lubricating base oil is not particularly limited but is preferably 40 or less, more preferably 35 or less, more preferably 30 or less.
The% C _A of the lubricating base oil is not particularly limited, but is preferably 3 or less, more preferably 2 or less, and still more preferably 1 or less.

Kinematic viscosity at 100 ° C. of the lubricating base oil is not particularly limited, preferably not more than 4.3 mm ² / s, more preferably less 4.2 mm ² / s, more preferably not more than 4.0 mm ² / s. By setting the kinematic viscosity at 100 ° C. to 4.3 mm ² / s or less, it is possible to obtain a lubricating oil composition having a smaller frictional resistance at a lubrication point because the fluidic resistance is reduced.
On the other hand, the kinematic viscosity at 100 ° C. of the lubricating base oil is preferably 2.0 mm ² / s or more, more preferably 2.2 mm ² / s or more, and still more preferably 2.4 mm ² / s or more. By setting the thickness to 2.0 mm ² / s or more, it is possible to obtain a lubricating oil composition in which the oil film formation is sufficient, the lubricity is better, and the evaporation loss of the base oil under high temperature conditions is smaller.

  The viscosity index of the lubricating base oil is not particularly limited, but is preferably 80 or more, more preferably 90 or more, and particularly preferably 100 or more. By setting the viscosity index to 80 or more, it is possible to obtain a composition which is more excellent in fatigue life, extreme pressure after initial use and after long-term use.

  The sulfur content of the lubricating base oil is not particularly limited, but is preferably 100 mass ppm or less, more preferably 50 mass ppm or less, still more preferably 10 mass ppm or less, and particularly preferably 1 mass ppm or less.

  In addition, when lubricating base oil is a mixture, the said property is judged as the said mixture, and it does not depend on the property of each base oil which comprises a mixture.

  The lubricating oil composition of the present invention contains a molybdenum compound as the component (B).

  As a molybdenum compound used by this invention, various organic molybdenum compounds, such as an organic molybdenum compound containing (B1) sulfur, or an organic molybdenum compound which does not contain sulfur as a (B2) structure element, are mentioned.

  First, as the organic molybdenum compound containing (B1) sulfur, molybdenum dithiophosphate, molybdenum dithiocarbamate and the like can be mentioned.

  As a molybdenum dithiophosphate, the compound represented by following General formula (2) is mentioned, for example.

In the above general formula (2), R ^{1 to} R ⁴ each independently represent an alkyl group having 2 to 30 carbon atoms, preferably 5 to 18 carbon atoms, more preferably 5 to 12 carbon atoms, or 6 to 18 carbon atoms And preferably represent a hydrocarbon group such as an (alkyl) aryl group having 10 to 15 carbon atoms. In addition, Y ^{1 to} Y ⁴ each independently represent a sulfur atom or an oxygen atom.

  As a molybdenum dithiocarbamate, the compound represented by following General formula (3) can be mentioned, for example.

In the above general formula (3), R ^{5 to} R ⁸ each independently represent an alkyl group having 2 to 24 carbon atoms, preferably 4 to 13 carbon atoms, or 6 to 24 carbon atoms, preferably 10 to 15 carbon atoms Indicates a hydrocarbon group such as an (alkyl) aryl group. Y ⁵ , Y ⁶ , Y ⁷ and Y ⁸ each independently represent a sulfur atom or an oxygen atom.

  Moreover, as organic molybdenum compounds containing sulfur other than these, molybdenum compounds (for example, molybdenum oxides such as molybdenum dioxide and molybdenum trioxide, orthomolybdic acid, paramolybdic acid, molybdic acids such as (poly) sulfurized molybdic acid, Molybdates of these molybdic acids, molybdates such as ammonium salts, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, molybdenum sulfides such as polysulfurized molybdenum, sulfurized molybdenum acids, metal salts or amine salts of sulfurized molybdic acids, sulfurized molybdic acids, chlorides Molybdenum halides such as molybdenum) and sulfur-containing organic compounds (eg, alkyl (thio) xanthates, thiadiazoles, mercaptothiadiazoles, thiocarbonates, tetrahydrocarbylthiuram disulfides, bis (di (thio) hydrocarbons) Or a sulfur-containing molybdenum compound such as the above-mentioned molybdenum sulfide, sulfurized molybdic acid or the like and a complex element with disulfide, organic (poly) sulfide, sulfurized ester, etc. or other organic compounds; Or a complex with an organic molybdenum compound, succinimide, organic acid, alcohol or the like, or elemental sulfur, hydrogen sulfide, phosphorus pentasulfide, sulfur oxide, inorganic sulfide, hydrocarbyl (poly ) Constituent elements described in the section of sulfur sources such as sulfides, sulfurized olefins, sulfurized esters, sulfurized waxes, sulfurized carboxylic acids, sulfurized alkylphenols, thioacetamides, thioureas, and sulfur-free organic molybdenum compounds as constituent elements described later Molybdenum free of sulfur as Sulfur-containing organic molybdenum obtained by reacting a compound with an organic compound containing no sulfur such as an amine compound, a succinimide, an organic acid or an alcohol described in the section of the organic molybdenum compound containing no sulfur as a constituent element described later Various things, such as a compound, can be mentioned. Specific examples thereof include organic molybdenum compounds as described in JP-A-56-10591 and U.S. Pat. No. 4,263,152.

  Specific examples of the organic molybdenum compound containing no sulfur as a constituent element (B2) include a molybdenum-amine complex, a molybdenum-succinimide complex, a molybdenum salt of an organic acid, a molybdenum salt of an alcohol, and the like. Molybdenum-amine complexes, molybdenum salts of organic acids and molybdenum salts of alcohols are preferred.

  As the organic molybdenum compound according to the present invention, a sulfur-containing organic molybdenum compound is preferable, and it is particularly preferable to use a molybdenum dithiocarbamate, from the point of being excellent in the friction reducing effect.

In the lubricating oil composition used in the present invention, the content of the organic molybdenum compound (B) is preferably 20 mass ppm or more, more preferably 60 mass ppm or more, and 100 mass as a molybdenum element equivalent amount based on the total mass of the composition. More preferred is ppm or more, and particularly preferred is 150 mass ppm or more. If the content is less than 20 mass ppm, the fuel saving effect can not be expected.
On the other hand, 1000 mass ppm or less is preferable, 800 mass ppm or less is more preferable, and 600 mass ppm or less is more preferable. If the content exceeds 1000 mass ppm, the stability of the lubricating oil composition particularly at high temperatures tends to decrease, which is not preferable.

The lubricating oil composition of the present invention contains, as the component (C), a thiophosphoric acid ester having a carboxy group at the end shown in the following formula (1).

In formula (1), R ₁ represents a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, R ₂ represents a hydrocarbyl group having 1 to 20 carbon atoms, and R ₃ represents a bivalent hydrocarbyl group having 1 to 8 carbon atoms.

The carbon number of the hydrocarbyl group of R ₁ and R ₂ is 1-20, preferably 1-12, more preferably 1-8.

Examples of the hydrocarbyl group of R ₁ and R ₂ include an alkyl group, a cycloalkyl group, an alkyl cycloalkyl group, an aryl group and an alkyl aryl group. More specifically, n-butyl, isobutyl, tert-butyl, cyclopentyl, cyclohexyl, methylcyclopentyl, phenyl, benzyl, tolyl (cresyl), xylenyl and the like can be mentioned. The hydrocarbyl group may be saturated or unsaturated, linear or branched.

  Among these, a saturated hydrocarbon group is preferable, and an alkyl group is particularly preferable.

The carbon number of the divalent hydrocarbyl group of R ₃ is 1 to 8, preferably 2 to 6, and more preferably 2 to 4.

Examples of the hydrocarbyl group R _3, an alkylene group, a cycloalkylene group, an alkyl cycloalkylene group. More specifically, a methylene group, an ethylene group, etc. are mentioned. The hydrocarbyl group may be saturated or unsaturated, linear or branched.

  Among these, a saturated hydrocarbon group is preferable, and an alkylene group is particularly preferable.

The content of the thiophosphate having a carboxy group at the end shown in the formula (1) is 5 mass ppm or more, more preferably 25 mass ppm or more, and 50 mass ppm or more, in terms of phosphorus element equivalent and total amount of composition. More preferably, 100 mass ppm or more is particularly preferable. If the content is less than 5 mass ppm, the effect of improving the wear resistance and the friction characteristics tends to be insufficient.
On the other hand, content is 500 mass ppm or less, 400 mass ppm or less is preferable, and 300 mass ppm or less is more preferable. Even if it exceeds 500 mass ppm, the further improvement effect of the abrasion resistance corresponding to the content can not be obtained, and the oxidation stability and the sludge inhibition tend to be lowered.

  The lubricating oil composition of the present invention contains an alkali metal and / or alkaline earth metal detergent as component (D).

  Specific examples of the alkali metal and / or alkaline earth metal-based detergent may include, for example, sulfonates, phenates and salicylates of alkali metals and / or alkaline earth metals, and one or two selected from these. More than one type of metal detergent can be used.

  Examples of the sulfonates more specifically include metal salts of alkyl aromatic sulfonic acids obtained by sulfonation of alkyl aromatic compounds having a molecular weight of 100 to 1,500, preferably 200 to 700, for example. Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid.

  More specifically, the phenate is an alkylphenol having at least one linear or branched alkyl group having 4 to 30, preferably 6 to 18 carbon atoms, and an alkylphenol obtained by reacting this alkylphenol with sulfur Examples thereof include metal salts of Mannich reaction products of sulfides or alkylphenols obtained by reacting this alkylphenol with formaldehyde.

  As the salicylate, more specifically, metal salts of alkylsalicylic acid having at least one linear or branched alkyl group having 4 to 30, preferably 6 to 18 carbon atoms can be mentioned.

  Not only neutral salts (normal salts) but also these neutral salts (normal salts) and excess alkali metal and / or alkaline earth metal salts, alkali metals and / or alkaline earths as the above-mentioned sulfonates, phenates and salicylates Basic salts obtained by heating a metalloid base (hydroxides and / or oxides of alkali metals and / or alkaline earth metals) in the presence of water, and neutral salts (normal salts) in the presence of carbon dioxide gas Also included are overbased salts (superbasic salts) which are obtained by reaction of (iii) with an alkali metal and / or alkaline earth metal base.

  Examples of the alkali metal and / or alkaline earth metal include sodium, potassium, magnesium, calcium and the like, among which magnesium and calcium are preferable, and calcium is particularly preferable.

  As the alkali metal and / or alkaline earth metal detergent, calcium sulfonate is most preferable.

  The base number of the alkali metal and / or alkaline earth metal detergent is not particularly limited, but is preferably 100 to 600 mg KOH / g, more preferably 150 to 500 mg KOH / g, and still more preferably 200 to 400 mg KOH, from the viewpoint of securing oxidation stability. / G is more preferable.

The content of the alkali metal and / or alkaline earth metal-based detergent is preferably 10 mass ppm or more, more preferably 40 mass ppm or more, and still more preferably 70 mass ppm or more on the basis of the total mass of the composition in terms of metal element.
On the other hand, from the viewpoint of preventing a decrease in friction coefficient due to clogging of the friction material of the clutch plate, 1000 mass ppm or less is preferable, 600 mass ppm or less is more preferable, 400 mass ppm or less is more preferable, 200 mass ppm or less is particularly preferable preferable.

The lubricating oil composition of the present invention preferably contains, as component (E), a pour point depressant, if necessary. The inclusion of a pour point depressant is preferable because the low temperature fluidity of the lubricating oil composition can be improved.
As the pour point depressant, any known pour point depressant can be selected, but a polymethacrylate based pour point depressant is particularly preferable. The weight-average molecular weight of the pour point depressant is preferably 10,000 or more, and more preferably 50,000 or more. Moreover, it is preferable that it is 300,000 or less, 200,000 or less is more preferable, and 150,000 or less is still more preferable. If the weight average molecular weight is more than 300,000, the shear stability of the composition is not preferable. If it is less than 10,000, the effect as a pour point effect agent is small. The content of the pour point depressant is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total amount of the lubricating oil composition. 5 mass% or less is further preferable, 2 mass% or less is particularly preferable, and 1 mass% or less is most preferable. If the amount added is more than 20% by mass, the shear stability of the composition is unfavorably reduced, and if less than 0.01% by mass, the effect as a pour point effect agent is small.
When a synthetic oil base oil is used as the lubricant base oil, the pour point depressant may not necessarily be contained. However, when a mineral oil base oil is used as the lubricant base oil, the pour point depressant is used. It is preferable to contain

  In the lubricating oil composition of the present invention, known lubricating oil additives such as ashless dispersants, antiwear agents, antioxidants, friction modifiers, metal deactivators, corrosion prevention, for the purpose of further enhancing performance The various additives represented by an agent, an antifoamer, a coloring agent etc. can be mix | blended individually or in combination of several types.

  As the ashless dispersant, any compound generally used as an ashless dispersant for lubricating oil can be used. For example, succinimide having an alkyl group or alkenyl group having 40 to 400 carbon atoms, benzylamine, polyamine and the like and These include boron compounds, phosphorus compounds, sulfur compounds, derivatives modified with oxygen-containing organic compounds and the like, and the like.

  As the antiwear agent, any compound generally used as an antiwear agent for lubricating oils can be used, and examples thereof include phosphorus and / or sulfur-containing antiwear agents and the like.

  Examples of the antioxidant include phenol-based and amine-based ashless antioxidants, and copper-based and molybdenum-based metal-based antioxidants.

  As the friction modifier, any compound generally used as a friction modifier for lubricating oils can be used, and for example, molybdenum-based friction modifiers, amine compounds, imide compounds, fatty acid esters, fatty acid amides, fatty acids, aliphatic And ash-free friction modifiers such as alcohols and aliphatic ethers.

  As a metal deactivator, imidazoline, pyrimidine derivative, alkyl thiadiazole, mercaptobenzothiazole, benzotriazole or derivative thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bisdialkyldithio A carbamate, 2- (alkyl dithio) benzimidazole, and (beta)-(o- carboxy benzylthio) propion nitrile etc. are mentioned.

  As the corrosion inhibitor, any compound generally used as a corrosion inhibitor for lubricating oils can be used, and examples thereof include benzotriazole-based, tolyltriazole-based and imidazole-based compounds.

  As the antifoaming agent, any compound generally used as an antifoaming agent for lubricating oil can be used, and examples thereof include silicones such as dimethyl silicone and fluorosilicone, alkenyl succinic acid derivatives, polyhydroxy aliphatic alcohols and so on. Examples thereof include esters of chain fatty acids, methyl salicylate and o-hydroxybenzyl alcohol.

  The blending ratio in the case of blending the various additives described above is not particularly limited, and generally, within the range of 0.001 to 10% by mass based on the total amount of the lubricating oil composition, taking into consideration the respective objects and effects. Can be determined appropriately.

The lubricating oil composition of the present invention may contain a viscosity index improver, but it is more preferable not to contain it.
Such viscosity index improvers include known non-dispersed or dispersed viscosity index improvers. Examples of the non-dispersed viscosity index improver include olefin polymers such as polymethacrylate, ethylene-propylene copolymer, styrene-diene copolymer, polyisobutylene and polystyrene. Further, as the dispersion type viscosity index improver, there can be mentioned a polymer obtained by copolymerizing the monomer forming the non-dispersion type viscosity index improver and the nitrogen-containing monomer.
The content ratio of the viscosity index improver in the lubricating oil composition of the present invention is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, and 0 to 3% by mass based on the total amount of the oil composition. More preferably, it is most preferable not to contain substantially.

The kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 2.0 mm ² / s or more, more preferably 2.2 mm ² / s or more. Sufficient lubricity can be ensured by setting it as 2.0 mm < ² > / s or more.
Meanwhile, the kinematic viscosity at 100 ° C., preferably not more than 5.4 mm ² / s, more preferably at most 5.0 mm ² / s. By setting it as 5.4 mm < ² > / s or less, the lubricating oil composition excellent in the low temperature viscosity characteristic can be obtained.

Kinematic viscosity at 40 ° C. of the lubricating oil composition of the present invention is preferably not more than 25.0 mm ² / s, more preferably not more than 22.5 mm ² / s, more preferably not more than 20.0 mm ² / s. By setting the kinematic viscosity at 40 ° C. to 25.0 mm ² / s or less, it is possible to obtain a lubricating oil composition having a smaller frictional resistance at a lubrication point because the fluidic resistance is reduced.
On the other hand, the kinematic viscosity of the lubricating oil composition at 40 ° C. is preferably 4.0 mm ² / s or more, more preferably 6.0 mm ² / s or more, and still more preferably 8.0 mm ² / s or more. By setting the thickness to 4.0 mm ² / s or more, it is possible to obtain a lubricating oil composition having sufficient oil film formation, better lubricity, and smaller evaporation loss of the base oil under high temperature conditions.

  The application of the lubricating oil composition of the present invention is not particularly limited and can be used for any application, but by containing a specific amount of a thiophosphate having a carboxy group at the end shown in Formula (1) as component (C), Since it is excellent in clutch torque capacity and extreme pressure property, reducing the friction coefficient between metals at the time of low temperature, it can be used suitably especially for an automatic transmission.

  EXAMPLES The present invention will be specifically described by way of the following examples, but the present invention is not limited to these examples.

(Examples 1 to 6 and Comparative Examples 1 to 8)
A lubricating oil composition having the composition shown in Table 1 was prepared. The addition amount (mass% or mass ppm) of each additive is based on the total amount of the composition. The properties of each lubricating oil composition were evaluated and listed in Table 1.

Claims (4)

(A) A lubricant base oil having a kinematic viscosity of 2.0 to 4.3 mm ² / s at 100 ° C. , (B) 20 to 1000 mass ppm of the molybdenum compound in terms of the total amount of the composition of the molybdenum compound, ) 5 to 500 mass ppm based on the total amount of the composition, and (D) alkali metal and / or alkaline earth metal based cleaning agent as metal element conversion of thiophosphate having a carboxy group shown in the following formula (1): 10 to 1000 mass ppm based on the total amount of the composition , and (E) 0.01 to 1 mass% of the pour point depressant based on the total amount of the composition, and the kinematic viscosity of the lubricating oil composition at 40 ° C. is 4 to 25 mm A lubricating oil composition for use in an automatic transmission , characterized in that it is ² / s .

(In formula (1), R ₁ represents a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, R ₂ represents a hydrocarbyl group having 1 to 20 carbon atoms, and R ₃ represents a bivalent hydrocarbyl group having 1 to 8 carbon atoms .)   The lubricating oil composition according to claim 1, wherein the component (D) is calcium sulfonate. (A) a lubricating base oil,% _{C P} is 60 or more,% _{C N} is less than 40,% _{C A} lubricating oil composition according to claim 1 or 2, characterized in that is 3 or less. 1 00 lubricating oil composition according to any one of claims 1 to 3, kinematic viscosity at ℃ is characterized in that it is a 2.0~5.4mm ² / s for the lubricating oil composition.