JP6378824B2 - Lubricating oil composition for automatic transmission - Google Patents

Description

  The present invention relates to a lubricating oil composition for an automatic transmission, and more particularly to a lubricating oil composition for an automatic transmission suitable for an automatic stepped transmission.

  As a lubricating oil composition for an automatic transmission, it is necessary to ensure the clutch torque capacity and extreme pressure, and a technique using a conventionally used ashless dispersant or friction modifier (for example, Patent Document 1, In 2), it has been difficult to significantly reduce the friction coefficient between metals while ensuring the clutch torque capacity and extreme pressure characteristics.

JP 2000-63869 A JP 2004-331721 A

  In view of the circumstances as described above, the present invention provides a lubricating oil composition for an automatic transmission capable of greatly reducing the reduction in the coefficient of friction between metals while ensuring the clutch torque capacity and extreme pressure. With the goal.

  As a result of intensive studies on the above problems, the present inventors have completed the present invention.

  That is, the present invention comprises a lubricating base oil, (A) a molybdenum compound having a molybdenum element amount of 1 mass ppm to 1000 mass ppm, (B) a phosphorous acid ester having a phosphorus element amount of 20 mass ppm to 1000 mass ppm, and (C) It is related with the lubricating oil composition for automatic transmissions containing 10 mass ppn-400 mass ppm as boron element amount of a boron-type dispersing agent.

  The present invention also relates to the above-described lubricating oil composition for an automatic transmission, which is used for an automatic stepped transmission.

  The lubricating oil composition for an automatic transmission according to the present invention is suitable for an automatic transmission having a good clutch torque capacity and extreme pressure characteristics while greatly reducing the coefficient of friction between metals in order to save fuel. It is.

  Hereinafter, the present invention will be described in detail.

  As the lubricating base oil according to the present invention, a base oil usually used as a lubricating base oil can be used. Examples thereof include mineral oil base oils, synthetic base oils, and mixtures thereof.

  As a mineral oil base oil, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining. In addition, paraffinic and naphthenic mineral oil base oils, normal paraffins, isoparaffins, and the like, which are refined by appropriately combining purification treatments such as sulfuric acid washing and clay treatment, and the like.

  There are no particular restrictions on the method for producing the mineral base oil, but for example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and reduced pressure distillation can be subjected to solvent removal, solvent extraction, hydrocracking, solvent removal. Oils such as paraffinic and naphthenic oils that are refined by a single or a combination of two or more purification treatments such as wax, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment can be used. These base oils may be used alone or in combination of two or more at any ratio.

Preferred mineral oil base oils include the following base oils.
[1] Distilled oil obtained by atmospheric distillation of paraffin-based crude oil and / or mixed-base crude oil;
[2] Vacuum distillation distillate (WVGO) of paraffin base crude oil and / or mixed base crude oil at atmospheric distillation residue;
[3] A wax obtained by a lubricant dewaxing step and / or a Fischer-Tropsch wax produced by a GTL process or the like;
[4] Mild hydrocracking treatment oil (MHC) of one or two or more mixed oils selected from [1] to [3];
[5] A mixed oil of two or more oils selected from [1] to [4];
[6] Degassed oil (DAO) of [1], [2], [3], [4] or [5];
[7] Mild hydrocracking treatment oil (MHC) of [6];
[8] A mixed oil of two or more kinds of oils selected from [1] to [7] is used as a feedstock oil, and this feedstock oil and / or a lubricating oil fraction recovered from this feedstock oil is used as a normal oil fraction. A lubricating oil obtained by refining by a refining method and collecting a lubricating oil fraction.

  The normal refining method here is not particularly limited, and a refining method used in the production of the lubricating base oil can be arbitrarily employed. Examples of conventional purification methods include (a) hydrorefining such as hydrocracking and hydrofinishing, (b) solvent purification such as furfural solvent extraction, and (c) dewaxing such as solvent dewaxing and catalytic dewaxing. And (d) white clay refining with acid clay and activated clay, and (e) chemical (acid or alkali) purification such as sulfuric acid washing and caustic soda washing. In the present invention, one or more of these can be used in any combination and in any order.

As the mineral oil base oil used in the present invention, a base oil obtained by further subjecting the base oil selected from the above [1] to [8] to the following treatment is particularly preferable.
That is, the base oil selected from the above [1] to [8] is used as it is, or the lubricating oil fraction recovered from this base oil is hydrocracked or wax-isomerized, and the product is used as it is or from this. Collect the fraction, and then perform dewaxing treatment such as solvent dewaxing or contact dewaxing, and then solvent refining treatment, or after solvent refining treatment, dewaxing such as solvent dewaxing or contact dewaxing Hydrocracked mineral oil and / or wax isomerized isoparaffinic base oil produced by treatment is preferably used. The hydrocracked mineral oil and / or wax isomerized isoparaffin base oil is preferably used in an amount of 30% by mass or more, more preferably 50% by mass or more, and particularly preferably 70% by mass or more based on the total amount of the base oil.

  Synthetic lubricating base oils include, for example, poly α-olefins or hydrides thereof, isobutene oligomers or hydrides thereof, isoparaffins, alkylbenzenes, alkylnaphthalenes, diesters (for example, ditridecylglutarate, di-2-ethylhexyl adipate, Diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, etc.), polyol esters (eg, trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate, etc.), Polyoxyalkylene glycol, dialkyl diphenyl ether, polyphenyl ether and the like can be mentioned.

  Preferable synthetic lubricating base oils include poly α-olefins. The poly α-olefin is typically an α-olefin oligomer or co-oligomer having 2 to 32 carbon atoms, preferably 6 to 16 (eg, 1-octene oligomer, 1-decene oligomer, ethylene-propylene co-oligomer). And hydrides thereof.

  There are no particular restrictions on the method for producing the poly-α-olefin, but for example, aluminum trichloride, boron trifluoride or boron trifluoride and water, alcohol (eg, ethanol, propanol or butanol), carboxylic acid, or ester (eg, acetic acid) And polymerization of α-olefins in the presence of a polymerization catalyst such as a Friedel-Crafts catalyst containing a complex with ethyl or ethyl propionate).

  The lubricating base oil may be a mixture of two or more mineral base oils or a mixture of two or more synthetic base oils, and is a mixture of a mineral base oil and a synthetic base oil. There is no problem. And the mixing ratio of 2 or more types of base oil in the said mixture can be chosen arbitrarily.

Kinematic viscosity at 100 ° C. of the lubricating base oil is not particularly limited but is preferably 5.0 mm ² / s or less, more preferably 4.5 mm ² / s, more preferably less 4.0 mm ² / s, 3.6 mm ² / s or less is particularly preferable, and 3.3 mm ² / s or less is most preferable. By setting the kinematic viscosity at 100 ° C. to 5.0 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 fluid resistance becomes smaller.
On the other hand, the kinematic viscosity at 100 ° C. of the lubricating base oil is preferably at least 0.5 mm ² / s, more preferably at least 1.0 mm ² / s, still more preferably at least 1.2 mm ² / s. By setting the kinematic viscosity at 100 ° C. to 0.5 mm ² / s or more, an oil film is sufficiently formed, the lubricity is excellent, and a lubricating oil composition having a smaller base oil evaporation loss under high temperature conditions is obtained. It becomes possible.

The kinematic viscosity at 40 ° C. of the lubricating base oil is not particularly limited, but is preferably 50.0 mm ² / s or less, more preferably 40.0 mm ² / s or less, and further preferably 30.0 mm ² / s or less. By setting the kinematic viscosity at 40 ° C. to 50.0 mm ² / s or less, it is possible to obtain a lubricating oil composition having a smaller frictional resistance because the fluid resistance becomes smaller.
On the other hand, the kinematic viscosity at 40 ° C. of the lubricating base oil is preferably at least 1.0 mm ² / s, more preferably at least 3.0 mm ² / s, still more preferably at least 5.0 mm ² / s. By setting the kinematic viscosity at 40 ° C. to 1.0 mm ² / s or more, an oil film is sufficiently formed, the lubricity is excellent, and a lubricating oil composition having a smaller base oil evaporation loss under high temperature conditions is obtained. It becomes possible.

  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 that is more excellent in fatigue life, extreme pressure after initial use and long-term use.

  Although there is no restriction | limiting in particular in sulfur content of lubricating base oil, 100 mass ppm or less is preferable, 50 mass ppm or less is more preferable, 10 mass ppm or less is more preferable, 1 mass ppm or less is especially preferable. By setting the sulfur content to 100 mass ppm or less, a composition that is more excellent in thermal and oxidation stability can be obtained.

  The lubricating oil composition for automatic transmissions of the present invention (hereinafter also simply referred to as the lubricating oil composition of the present invention) contains a molybdenum compound as component (A).

  Examples of the molybdenum compound used in the present invention include various organic molybdenum compounds such as (A1) an organic molybdenum compound containing sulfur or (A2) an organic molybdenum compound not containing sulfur as a constituent element.

  First, (A1) sulfur-containing organic molybdenum compounds include molybdenum dithiophosphate, molybdenum dithiocarbamate, and the like.

  As molybdenum dithiophosphate, the compound represented by following General formula (1) is mentioned, for example.

In the general formula (1), R ^{1 to} R ⁴ are each independently 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. , Preferably a hydrocarbon group such as an (alkyl) aryl group having 10 to 15 carbon atoms. 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 (2) can be mentioned, for example.

In the general formula (2), R ^{5 to} R ⁸ are each independently 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. A hydrocarbon group such as an (alkyl) aryl group is shown. Y ⁵ , Y ⁶ , Y ⁷ and Y ⁸ each independently represent a sulfur atom or an oxygen atom.

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

  (A2) Specific examples of organic molybdenum compounds that do not contain sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, organic acid molybdenum salts, alcohol molybdenum salts, and the like. Preference is given to molybdenum-amine complexes, molybdenum salts of organic acids and molybdenum salts of alcohols.

  As the organomolybdenum compound according to the present invention, a sulfur-containing organomolybdenum compound is preferable, and molybdenum dithiocarbamate is most preferably used from the viewpoint of excellent friction reduction effect.

In the lubricating oil composition used in the present invention, the content of the (A) organomolybdenum compound is preferably 1 ppm by mass or more, more preferably 10 ppm by mass or more, more preferably 30 ppm by mass as the total amount of the composition, and in terms of molybdenum element. More preferably, ppm or more is more preferable, 50 mass ppm or more is especially preferable, and 100 mass ppm or more is the most preferable. When the content is less than 1 ppm by mass, a fuel saving effect cannot be expected.
On the other hand, 1000 mass ppm is preferable, 800 mass ppm or less is more preferable, and 600 mass ppm or less is more preferable. When the content exceeds 1000 mass ppm, the stability of the lubricating oil composition, particularly at high temperatures, tends to decrease, such being undesirable.

  The lubricating oil composition of the present invention contains a phosphite as the component (B). The phosphite is a compound represented by the following general formula (3) or (4).

In the general formulas (3) and (4), R ^{9 to} R ¹² are each independently a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a sulfur-containing hydrocarbon group, or an aryl group having 6 to 15 carbon atoms. Represent. R ¹³ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, a sulfur-containing hydrocarbon group, or an aryl group having 6 to 15 carbon atoms.

  Carbon number of a hydrocarbon group is 1-20, Preferably it is 6-18, More preferably, it is 8-16. Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, and an alkylcycloalkyl group. Examples of the alkyl group, cycloalkyl group, and alkylcycloalkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a cyclopentyl group, a cyclohexyl group, and a methylcyclopentyl group.

  The aryl group has 6 to 15 carbon atoms, preferably 6 to 9 carbon atoms. Examples of the aryl group include a phenyl group, a benzyl group, a tolyl group (cresyl group), and a xylenyl group.

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

  As the phosphite, a monoalkyl phosphite, a dialkyl phosphite, a trialkyl phosphite and a mixture of two or more thereof are preferable.

The content of (B) phosphite is preferably 20 ppm by mass or more, more preferably 50 ppm by mass or more, and even more preferably 100 ppm by mass or more in terms of the total amount of the composition and in terms of phosphorus element. If the content is less than 20 ppm by mass, the effect of improving wear resistance and friction characteristics tends to be insufficient.
On the other hand, the content is 1000 mass ppm or less, preferably 800 mass ppm or less, and more preferably 600 mass ppm or less. Even if it exceeds 1000 ppm by mass, a further improvement effect of wear resistance corresponding to the content cannot be obtained, and oxidation stability and sludge suppression tend to decrease.

  The lubricating oil composition of the present invention contains a boron-based dispersant as the component (C).

  The boron-based dispersant can be usually obtained by allowing boric acid to act on a compound used as an ashless dispersant and neutralizing a part or all of the remaining amino group and / or imino group.

Specific examples of the ashless dispersant include nitrogen-containing compounds having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, or derivatives thereof. The alkyl group or alkenyl group may be linear or branched, but is preferably a branch derived from an olefin oligomer such as propylene, 1-butene or isobutylene, or a co-oligomer of ethylene and propylene. An alkyl group and a branched alkenyl group.
One of these compounds may be used alone, or a mixture of two or more compounds in an arbitrary mixing ratio may be used.

More specifically,
(I) Succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof (ii) At least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule Examples include benzylamine having a derivative thereof, or (iii) a polyamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or one or more compounds selected from derivatives thereof. it can.

  (I) More specifically, examples of the succinimide include compounds represented by the following general formula (5) or (6).

In the general formulas (5) and (6), R ^{14 to} R ¹⁶ individually represent an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and b is 1 to 5, Preferably the number of 2-4 is shown, c is 0-4, Preferably the number of 1-3 is shown, respectively.

  Although the production method of this succinimide is not limited at all, for example, after reacting polyolefin such as propylene oligomer, polybutene, ethylene-propylene copolymer and the like with maleic anhydride to obtain alkenyl succinic anhydride, diethylenetriamine , Imidized with polyamines such as triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and the like.

  It should be noted that succinimide is added with a so-called monotype succinimide as represented by the general formula (5) in which succinic anhydride is added to one end of the polyamine and succinic anhydride is added to both ends of the polyamine. In addition, there are so-called bis-type succinimides represented by the general formula (6), any of which can also be used as a mixture thereof.

  More specifically, examples of benzylamine include compounds represented by the following general formula (7).

In the general formula (7), R ¹⁷ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350, and d represents a number of 1 to 5, preferably 2 to 4, respectively. Yes.

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

  More specifically, examples of the polyamine include compounds represented by the following general formula (8).

In the general formula (8), R ¹⁸ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350, and e represents a number of 1 to 5, preferably 2 to 4, respectively. Yes.

The production method of this polyamine is not limited at all. For example, after chlorinating a polyolefin such as propylene oligomer, polybutene, or ethylene-propylene copolymer, ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylene is added thereto. It can be obtained by reacting a polyamine such as pentamine or pentaethylenehexamine.

(C) The content of the boron-based dispersant is preferably 10 ppm by mass or more, more preferably 20 ppm by mass or more, and still more preferably 30 ppm by mass or more as the total amount of the composition-based boron element. If the content is less than 10 ppm by mass, the effect of addition is not observed, and the oxidation stability and sludge generation suppressing effect of the lubricating oil composition may be deteriorated.
On the other hand, 400 mass ppm or less is preferable, 300 mass ppm or less is more preferable, and 200 mass ppm or less is more preferable. Even if the content exceeds 400 mass ppm, the oxidation stability and the sludge formation suppressing effect sufficient for the content are not further improved, and the solubility in the base oil is lowered, which is not preferable.

  In the lubricating oil composition of the present invention, a known lubricating oil additive such as an ashless dispersant containing no boron, a metal-based detergent, an antioxidant, a pour point depressant, and friction adjustment is used for the purpose of further enhancing the performance. Various additives represented by an agent, a metal deactivator, a viscosity index improver, an extreme pressure additive, a corrosion inhibitor, an antifoaming agent, a colorant and the like can be used alone or in combination.

As the friction modifier that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as a friction modifier for lubricating oils can be used, but an alkyl group or alkenyl group having 6 to 30 carbon atoms, In particular, amine compounds, fatty acid esters, fatty acid amides, fatty acid metal salts, and the like having at least one straight-chain alkyl group or straight-chain alkenyl group having 6 to 30 carbon atoms in the molecule are included.
Among the amine compounds described above, succinimide and the like which are a reaction product with polyamine are also included. These include those modified with boron compounds and phosphorus compounds.
Examples of the amine compound include linear or branched, preferably linear aliphatic monoamines having 6 to 30 carbon atoms, linear or branched, preferably linear aliphatic polyamines, or fatty acids thereof. An alkylene oxide adduct of a group amine can be exemplified. Examples of fatty acid esters include esters of linear or branched, preferably linear, fatty acids having 7 to 31 carbon atoms with aliphatic monohydric alcohols or aliphatic polyhydric alcohols. Examples of fatty acid amides include amides of linear or branched, preferably linear fatty acids having 7 to 31 carbon atoms, and aliphatic monoamines or aliphatic polyamines. Examples of the fatty acid metal salt include an alkaline earth metal salt (magnesium salt, calcium salt, etc.) or zinc salt of a linear or branched, preferably linear fatty acid having 7 to 31 carbon atoms. Among these friction modifiers, compounds having an amide bond in the molecule (amide compounds, imide compounds, urea compounds, etc.) tend to improve anti-shudder properties, and among them, those containing polyamines are particularly preferable. Most preferred are imide compounds containing polyamines.
In the present invention, one kind or two or more kinds of compounds arbitrarily selected from these friction modifiers can be contained in any amount, but usually the content thereof is a lubricating oil composition. It is desirable that the content is 0.01 to 5.0% by mass, preferably 0.03 to 3.0% by mass.

As the ashless dispersant not containing boron that can be used in combination with the lubricating oil composition of the present invention, any compound usually used as an ashless dispersant for lubricating oil can be used. For example, an alkyl having 40 to 400 carbon atoms is used. A nitrogen-containing compound having at least one group or alkenyl group in the molecule or a derivative thereof, or a modified product of alkenyl succinimide.
The alkyl group or alkenyl group may be linear or branched, but specific examples include an olefin oligomer such as propylene, 1-butene and isobutylene, and a co-oligomer of ethylene and propylene. Examples thereof include branched alkyl groups and branched alkenyl groups.
The alkyl group or alkenyl group has 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms. When the carbon number of the alkyl group or alkenyl group is less than 40, the solubility of the compound in the lubricating base oil decreases. On the other hand, when the carbon number of the alkyl group or alkenyl group exceeds 400, the low temperature of the lubricating oil composition Since fluidity | liquidity deteriorates, it is unpreferable respectively.
In addition, as a derivative of the nitrogen-containing compound mentioned as an example of the ashless dispersant, specifically, for example, a nitrogen-containing compound as described above, a monocarboxylic acid having 2 to 30 carbon atoms (fatty acid, etc.), oxalic acid, By reacting a polycarboxylic acid having 2 to 30 carbon atoms such as phthalic acid, trimellitic acid, pyromellitic acid, etc. to neutralize a part or all of the remaining amino group and / or imino group, or amidation, So-called acid-modified compounds; sulfur-modified compounds in which a sulfur compound is allowed to act on the nitrogen-containing compounds as described above; and modifications in which two or more types of modifications selected from acid-modified and sulfur-modified are combined with the nitrogen-containing compounds as described above Compounds and the like.
In the lubricating oil composition of the present invention, one or two or more compounds arbitrarily selected from these ashless dispersants can be used in any amount, but usually the content is It is desirable that the amount is 0.1 to 10% by mass based on the total amount of the lubricating oil composition.

Specific examples of the viscosity index improver that can be used in combination with the lubricating oil composition of the present invention include so-called copolymers of one or more monomers selected from various methacrylic acid esters or hydrogenated products thereof. Examples thereof include a non-dispersed viscosity index improver, or a so-called dispersed viscosity index improver obtained by copolymerizing various methacrylic esters containing a nitrogen compound. Specific examples of other viscosity index improvers include non-dispersed or dispersed ethylene-α-olefin copolymers (the α-olefin can be exemplified by propylene, 1-butene, 1-pentene, etc.) and hydrides thereof. , Polyisobutylene and hydrogenated products thereof, styrene-diene hydrogenated copolymer, styrene-maleic anhydride ester copolymer, and polyalkylstyrene.
The molecular weight of these viscosity index improvers needs to be selected in consideration of shear stability. Specifically, the number average molecular weight of the viscosity index improver is, for example, 5,000 to 150,000, preferably 5,000 to 35,000 in the case of dispersed and non-dispersed polymethacrylates. In the case of isobutylene or a hydride thereof, 800 to 5,000, preferably 1,000 to 4,000, and in the case of an ethylene-α-olefin copolymer or a hydride thereof, 800 to 150,000, preferably The thing of 3,000-12,000 is preferable.
Of these viscosity index improvers, when an ethylene-α-olefin copolymer or a hydride thereof is used, a lubricating oil composition having particularly excellent shear stability can be obtained.
In the present invention, one or two or more compounds arbitrarily selected from these viscosity index improvers can be contained in any amount, but the content thereof is usually a lubricating oil composition. It is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably not substantially used. “Not substantially used” means 0.1% by mass or less based on the total amount of the lubricating oil composition.

  As the metal-based detergent that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as a metal-based detergent for lubricating oil can be used. For example, an alkali metal or alkaline earth metal Sulfonates, phenates, salicylates, naphthenates, and the like can be used alone or in combination of two or more in the composition of the present invention. Examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include calcium and magnesium. In addition, calcium or magnesium sulfonates, phenates, and salicylates are preferably used as specific metal detergents. In addition, the total base number and addition amount of these metal detergents can be arbitrarily selected according to the required performance of the lubricating oil.

As the antioxidant that can be used in combination with the lubricating oil composition of the present invention, phenolic compounds and amine compounds that are generally used in lubricating oils 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, dialkyldiphenylamines, zinc dialkyldithiophosphates such as zinc di-2-ethylhexyldithiophosphate, (3,5-di-tert-butyl-4-hydroxyphenyl) fatty acid ( And an ester of monovalent or polyhydric alcohol such as methanol, octadecanol, 1,6 hexadiol, neopentyl glycol, thiodiethylene glycol, triethylene glycol, pentaerythritol and the like.
One kind or two or more kinds of compounds arbitrarily selected from these antioxidants can be contained in any amount, but the content is usually 0.00 on the basis of the total amount of the lubricating oil composition. It is desirable that it is 01-5.0 mass%.

As the pour point depressant that can be used in combination with the lubricating oil composition of the present invention, any compound usually used as a pour point depressant for lubricating oils can be used, but polymethacrylate pour point depressants are particularly preferred. . The weight average molecular weight of the pour point depressant is preferably 10,000 to 300,000, more preferably 50,000 to 200,000. The content of the pour point depressant is preferably 0.05 to 20% by mass based on the total amount of the lubricating oil composition.
When a synthetic base oil is used as the lubricating base oil, the pour point depressant is not necessarily contained. However, when a mineral base oil is used as the lubricating base oil, the pour point depressant is used. It is preferable to contain.

  As the metal deactivator that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as a metal deactivator for lubricating oils can be used. For example, imidazoline, pyrimidine derivatives, alkylthiadiazoles , Mercaptobenzothiazole, benzotriazole or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and β- ( o-carboxybenzylthio) propiononitrile and the like.

  As the extreme pressure additive that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as an extreme pressure additive for lubricating oils can be used. For example, disulfides, sulfurized olefins, sulfurized And sulfur compounds such as fats and oils. One kind or two or more kinds of compounds arbitrarily selected from these can be contained in any amount, but the content is usually 0.01 to 5. based on the total amount of the lubricating oil composition. It is preferably 0% by mass.

  As the corrosion inhibitor that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as a corrosion inhibitor for lubricating oils can be used. For example, benzotriazole-based, tolyltriazole-based, imidazole-based Compounds and the like.

  As an antifoaming agent that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as an antifoaming agent for lubricating oils can be used. For example, silicones such as dimethyl silicone and fluorosilicone can be used. Can be mentioned. One or two or more compounds arbitrarily selected from these can be contained in any amount, but the content is usually 0.001 to 0.00 on the basis of the total amount of the lubricating oil composition. It is desirable that it is 05 mass%.

  The colorant that can be used in combination with the lubricating oil composition of the present invention is arbitrary and can contain any amount, but the content is usually 0.001 to 1.% based on the total amount of the lubricating oil composition. It is preferably 0% by mass.

Kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 2.5 mm ² / s or higher, more preferably at least 2.7 mm ² / s, still more preferably at least 3.0 mm ² / s. By setting it to 2.5 mm ² / s or more, sufficient lubricity can be secured, and evaporation loss of the lubricating base oil can be suppressed.
Meanwhile, the kinematic viscosity at 100 ° C., preferably not more than 7.5 mm ² / s, more preferably less 7.0 mm ² / s, more preferably not more than 6.5 mm ² / s. By setting it as 7.5 mm < ² > / s or less, the lubricating oil composition excellent in the low temperature viscosity characteristic is obtained.

  The lubricating oil composition of the present invention can be suitably used for an automatic transmission having a torque converter, a wet clutch, a planetary gear, a gear bearing mechanism, an oil pump, a hydraulic control mechanism, and the like. In particular, it can be suitably used for an automatic stepped transmission that performs gear ratio switching stepwise.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Examples 1-8, Comparative Examples 1-8)
Lubricating oil compositions having the compositions shown in Table 1 were prepared. The addition amount (% by mass) 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.

(1) Using a SRV tester, the friction coefficient between metals at a temperature of 80 ° C., a load of 100 N, and an average sliding speed of 0.1 m / s was measured for each lubricating oil composition.
(2) In accordance with ASTM D3233, the seizure load at 290 rotations and 52 ° C. of each lubricating oil composition was measured using a Falex testing machine. In this test, the larger the seizure load, the better the seizure resistance.
(3) In accordance with JASO M348, SAE No. 2 μs (clutch torque capacity) of each lubricating oil composition at 100 ° C. and 5000 cycles was measured using a testing machine. In this test, the larger the value of μs, the better the clutch torque capacity.
(4) Based on JASO M349, dμ / dV (0.3 m / s) × 1000 at 80 ° C. of each lubricating oil composition was measured using an LVFA testing machine. In this test, the larger the value of dμ / dV (0.3 m / s) × 1000, the better the shudder resistance.
(5) In accordance with JASO M347, the kinematic viscosity reduction rate after 1 hour of each lubricating oil composition was measured using SONIC (ultrasonic shearing device). In this test, the smaller the kinematic viscosity reduction rate, the better the shear stability.

Claims (2)

Lubricating base oil, (A) Molybdenum compound as molybdenum element amount 1 mass ppm to 1000 mass ppm, (B) Phosphite ester as phosphorus element amount 20 mass ppm to 1000 mass ppm, and (C) Boron-based dispersion agent automatic transmission lubricating oil composition characterized by containing 10 mass pp m to 400 ppm by mass of boron element content. The lubricating oil composition for an automatic transmission according to claim 1, which is used for an automatic stepped transmission.