JP2021098762A - Gear oil composition - Google Patents

Abstract

To provide a gear oil composition capable of preferably using as a manual transmission fluid, that has improved shear stability, extreme pressure resistance, and fatigue resistance in a well-balanced manner.SOLUTION: The gear oil composition comprises: (A) (A1) an ester-based base oil of 0.5 to 25 mass% based on a total amount of a base oil; (A2) a lubricant base oil containing an API base oil classification group II base oil, an API base oil classification group III base oil, or an API base oil classification group IV base oil, or a mixture thereof; (B) ethylene-α-olefin copolymer having a kinematic viscosity of 500 to 3000 mm2/s at 100°C of 1.0 to 10.0 mass% based on the total amount of the composition; and a dithiophosphate triester compound having a carboxy group of 0.1 to 1.5 mass% based on the total amount of the composition.SELECTED DRAWING: None

Description

The present invention relates to a gear oil composition, and more particularly to a gear oil composition that can be suitably used as a lubricating oil for, for example, a manual transmission.

One of the means for improving fuel efficiency in gear devices such as transmissions and final stage transmissions is to use a low-viscosity lubricating oil in which a low-viscosity base oil is mixed with a viscosity index improver. Low viscosity lubricants can reduce agitation resistance and increase energy efficiency. However, when the viscosity of the lubricating oil is reduced, the oil film thickness tends to decrease, so that the fatigue resistance and extreme pressure resistance, which are important performances for the lubricating oil of the gear device, tend to decrease.

Another means of improving fuel efficiency is to reduce the weight of the device. For example, if the transmission is miniaturized, the weight of the device can be reduced, but in order to handle the same level of shaft output as before with the miniaturized transmission, the lubricating oil that lubricates the transmission has additional shear stability and poles. Pressure resistance and fatigue resistance are required. The same can be said for the lubricating oil of other gear devices such as the final stage transmission oil that lubricates the final stage transmission (differential gear).

Japanese Patent No. 5941530 International Publication No. 2010/11442 Japanese Patent No. 3882154

Patent Document 1, the (A) 100 kinematic viscosity at ℃ is 2~6mm ² / s,% _{C A} of 0.5% or less, mineral base oil is 7% or more tertiary carbon content, (B ) Poly-α-olefin and / or hydride thereof having a kinematic viscosity at 100 ° C. of 6 to 160 mm ² / s is 2 to 40% by mass based on the total amount of base oil, and (C) kinematic viscosity at 100 ° C. is 2 to 2. A base oil containing 5 to 20% by mass of an ester-based base oil of 10 mm ² / s based on the total amount of the base oil, and (D) a poly (meth) acrylate-based oil having a weight average molecular weight of 5,000 to 200,000. Described is a lubricating oil composition for a gear unit for an automobile, which contains a viscosity index improver and has a kinematic viscosity at 100 ° C. of 10 mm ^{2 / s or less.} However, considering the improvement in the required level for lubricating oil due to the miniaturization of gear devices such as transmissions, the compositions described in Patent Document 1 have shear stability, extreme pressure resistance (load bearing capacity), and fatigue resistance. In terms of sex, there was still room for improvement.

Patent Document 2, from (A) 1 or more kinematic viscosity at 100 ° C. kinematic viscosity at mineral and 100 ° C. is 2 to 20 mm ² / s is selected from polyolefin-based synthetic oil is 2 to 20 mm ² / s A base oil having a viscosity index of 120 or more, (B) an ethylene-α-olefin copolymer having a number average molecular weight of 2,000 to 10,000, (C) a specific sulfur-containing compound, and (D). It has a hydrocarbon group having 2 to 24 carbon atoms, which is selected from an organic molybdenum compound and (E) a phosphoric acid ester compound, a phosphite ester compound, a thiophosphate ester compound, and a thiosulfur ester compound. It contains a phosphorus-containing compound, and the content of the component (B) is 3 to 10% by mass, and the content of the component (C) is 1.2 to 2.0% by mass in terms of sulfur atom, based on the total amount of the composition. The content of the component (D) is 100 to 300% by mass in terms of molybdenum atom, and the content of the component (E) is 0.15 to 0.2% by mass in terms of phosphorus atom. Described are gear oil compositions having a mass ratio (S / P) of 8 to 11 to phosphorus atoms. Certainly, it is possible to improve extreme pressure resistance and wear resistance (wear prevention property) by blending the (D) organic molybdenum compound with the lubricating oil, but the composition described in Patent Document 2 can be used as a lubricating oil for a manual transmission. There is a problem that the organic molybdenum compound adversely affects the synchro property.

An object of the present invention is to provide a gear oil composition which can be preferably used as a manual transmission oil, which has improved shear stability, extreme pressure resistance (wear prevention property), and fatigue resistance in a well-balanced manner.

In one embodiment of the present invention, (A) (A1) ester-based base oil is 0.5 to 25% by mass based on the total amount of base oil, and (A2) API base oil classification group II base oil and API base oil. Lubricating oil base oil containing classification group III base oil, API base oil classification group IV base oil, or a mixture thereof, and (B) ethylene-α- having a ^{kinematic viscosity at 100 ° C. of 500 to 3000 mm 2 / s.} The olefin copolymer is 1.0 to 10.0% by mass based on the total amount of the composition, and (C) the dithiophosphate triester compound having a carboxy group is 0.1 to 1.5% by mass based on the total amount of the composition. It is a gear oil composition characterized by containing and.

According to the present invention, it is possible to provide a gear oil composition which can be preferably used as a manual transmission oil, which has improved shear stability, extreme pressure resistance (wear prevention property), and fatigue resistance in a well-balanced manner.

Hereinafter, the present invention will be described in detail. In the present specification, unless otherwise specified, the notation "A to B" for the numerical values A and B means "A or more and B or less". When a unit is attached only to the numerical value B in such a notation, the unit shall be applied to the numerical value A as well. The words "or" and "or" shall mean OR unless otherwise specified. In the present specification, the notation "E ₁ and / or E _{2 " for elements E 1} and E ₂ shall mean "E ₁ or E ₂ , or a combination thereof", and elements E ₁ , ..., _EN. (N is an integer of 3 or more) for the _{"E 1, ..., E N-} 1, and / or _{E N"} notation is _{"E 1, ..., E N-} 1, or _{E N,} or a combination thereof" the It shall mean. Further, in the present specification, magnesium is also included in "alkaline earth metal".

<(A) Lubricating oil base oil>
The lubricating oil base oil (hereinafter sometimes referred to as “component (A)”) in the gear oil composition of the present invention (hereinafter, may be simply referred to as “composition”) is (A1) ester-based base oil. (Hereinafter referred to as "base oil (A1)") is 0.5 to 25% by mass based on the total amount of base oil, and (A2) API base oil classification group II base oil and API base oil classification group III. It comprises an oil, or an API base oil classification group IV base oil, or a mixture thereof (hereinafter, may be referred to as "base oil (A2)").

An organic acid ester can be used as the base oil (A1). Examples of the base oil (A1) include esters of monohydric alcohols or polyhydric alcohols with monobasic acids or polybasic acids ((a) to (g) below).
(A) Ester of monohydric alcohol and monobasic acid;
(B) Ester of polyhydric alcohol and monobasic acid;
(C) Ester of monohydric alcohol and polybasic acid;
(D) Ester of polyhydric alcohol and polybasic acid;
(E) A mixed ester of a mixture of a monohydric alcohol and a polyhydric alcohol and a polybasic acid;
(F) Mixed ester of polyhydric alcohol and a mixture of monobasic acid and polybasic acid;
(G) A mixed ester of a mixture of a monohydric alcohol and a polyhydric alcohol and a mixture of a monobasic acid and a polybasic acid.

Examples of monohydric alcohols or polyhydric alcohols have 1 to 30 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 5 to 5 carbon atoms, which have a hydrocarbon group and one or more hydroxy groups. Eighteen monohydric or polyhydric alcohols can be mentioned.
As an example of a monobasic acid or a polybasic acid, it has a hydrocarbon group and one or more carboxy groups and has 2 to 30 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 6 to 6 carbon atoms. 18 monobasic acids or polybasic acids can be mentioned.
Hydrocarbon groups are obtained by removing one or more hydrogen atoms from the hydrocarbon molecule. Examples of hydrocarbons are chain saturated aliphatic hydrocarbons (ie alkanes), chain unsaturated aliphatic hydrocarbons (ie alkanes), cyclic saturated aliphatic hydrocarbons (ie cycloalkanes; one or more alkyl substitutions). Group-based), cyclic unsaturated aliphatic hydrocarbons (ie, cycloalkanes; may have one or more alkyl substituents), aromatic hydrocarbons (one or more alkyl substituents) It may have a group), etc. Examples of monovalent hydrocarbon groups contained in monohydric alcohols and monobasic acids include groups obtained by removing one hydrogen atom from these hydrocarbon molecules. Examples of polyhydric hydrocarbon groups contained in polyhydric alcohols and polybasic acids include groups obtained by removing two or more hydrogen atoms from these hydrocarbon molecules.

Preferred examples of monohydric alcohols are linear or branched alkyl monoalcohols having 1 to 30 carbon atoms; allyl alcohols, buthenols, hexenols, octenols, desenols, dodecenols, octadecenols (eg, oleyl alcohols, etc.) and the like. Examples thereof include linear or branched alkenyl monoalcohols of ~ 40 (the position of the double bond is arbitrary, but preferably other than the α-position of the hydroxy group), and mixtures thereof.

Preferred examples of the polyhydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and the like. Neopentyl glycol, isoprene glycol (3-methyl-1,3-butanediol), 1,2-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2-diethyl- 1,3-Propanediol (3,3-dimethylolpentane), 1,2-octanediol, 1,8-octanediol, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1 , 3-Pentanediol, 1,9-Nonandiol, 2-Butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptan), 2-Methyl-1,8-octanediol, 1, A linear or branched alkanediol having 2 to 30 carbon atoms, such as 10-decanediol and 1,12-dodecanediol (the position of substitution of the hydroxy group is arbitrary, but a plurality of hydroxy groups are bonded to the same carbon atom. (Preferably not); Linear or branched alkenediol having 4 to 30 carbon atoms (the substitution position of the hydroxy group is arbitrary, but it is preferable that a plurality of hydroxy groups are not bonded to the same carbon atom. The position of the double bond is arbitrary, but it is preferably not at the α-position of any hydroxy group.); Glycerin, trimethylolalkane (for example, trimethylolmethane, trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) ), 1,2,3-butanetriol, 1,2,4-butanetriol, 2-methyl-1,2,3-propanetriol, 1,2,3-pentanetriol, 1,2,4-pentane Triol, 1,2,5-pentanetriol, 1,3,5-pentanetriol, 2,3,4-pentanetriol, 3-methyl-1,2,3-butanetriol, 1,2,3-hexanetriol , 1,2,6-hexanetriol, 1,3,6-hexanetriol, 2,3,4-hexanetriol, 2-ethyl-1,2,3-butanetriol, 4-propyl-3,4,5 -Trivalent alcohols such as heptanetriol, pentamethylglycerin (2,4-dimethyl-2,3,4-pentantriol); erythritol, pentaerythritol, 1,2,3,4-butane Tetrol, 1,2,3,4-pentantetrol, 1,2,4,5-pentantetrol, 1,3,4,5-hexanetetrol, 1,2,5,6-hexanetetrol, Tetrahydric alcohols such as 2,3,4,5-hexanetetrol, diglycerin, sorbitan; pentahydric alcohols such as adonitol, arabitol, xylitol, allose, tarose, triglycerin; dipentaerythritol, sorbitol, mannitol, iditol, Hexic alcohols such as inditol and dalsitol; polyglycerin; and dehydration condensates thereof (intramolecular condensed compounds (for example, sorbitan, isosorbide, etc.). ), Intermolecular condensation compounds (eg, sorbitol glycerin condensate, etc.), or self-condensation compounds (eg, 2-8 mer of glycerin, 2-8 mer of trimethylol alkane such as ditrimethylol propane, dipentaerythritol, etc. 2 to tetramers of pentaerythritol, etc.)); and mixtures thereof and the like can be mentioned.

The monohydric or polyhydric alcohol is obtained by an addition reaction between the monohydric or polyhydric alcohol and an alkylene oxide having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms or a polymer or copolymer thereof. Alcohol alkylene oxide adducts may be used. In the alkylene oxide adduct of alcohol, a hydrogen atom is removed from the hydroxy group of the raw material alcohol, and between the oxygen atom of the hydroxy group and the carbon atom of the epoxide ring of the raw material alkylene oxide (or a polymer or copolymer thereof). A new C—O bond is formed in the epoxide ring of the raw material alkylene oxide (or a polymer or copolymer thereof), and a new hydroxy group is generated. Examples of alkylene oxides having 2 to 6 carbon atoms include ethylene oxide, propylene oxide, 1,2-epoxybutane (α-butylene oxide), 2,3-epoxybutane (β-butylene oxide), and 1,2-epoxy. Examples thereof include -1-methylpropane, 1,2-epoxyheptane and 1,2-epoxyhexane. Among these, ethylene oxide, propylene oxide, and butylene oxide are preferable, and ethylene oxide and propylene oxide are more preferable, from the viewpoint of excellent low friction. When two or more kinds of alkylene oxides are used, the polymerization form of the oxyalkylene group is not particularly limited, and for example, two or more kinds of alkylene oxides may be randomly copolymerized, and for example, 2 More than a species of alkylene oxide may be block copolymerized. Further, in the addition reaction of a polyhydric alcohol having two or more hydroxy groups (for example, 2 to 6) and an alkylene oxide (or a polymer or copolymer thereof), all the hydroxy groups of the raw material polyhydric alcohol May be involved in the addition reaction, or only some hydroxyl groups may be involved in the addition reaction.

As the monobasic acid, a fatty acid having 2 to 30 carbon atoms can be used. The fatty acid may be a straight chain fatty acid or a branched chain fatty acid. Further, the fatty acid may be a saturated fatty acid or an unsaturated fatty acid. Examples of fatty acids include acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, Saturated fatty acids such as heptadecanoic acid, octadecanoic acid, hydroxyoctadecanoic acid, nonadecanoic acid, eicosanoic acid, heneicosanoic acid, docosanoic acid, tricosanoic acid, tetracosanoic acid; acrylic acid, butenoic acid, pentenic acid, hexenoic acid, heptenoic acid, octenoic acid, Noneic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, octadecenoic acid, hydroxyoctadecenoic acid, nonadecenoic acid, eicosenoic acid, heneicosenoic acid, docosenoic acid, tricosenoic acid, Unsaturated fatty acids such as tetracosenoic acid; and mixtures thereof and the like can be mentioned.

The number of carbon atoms of the fatty acid is preferably 6 to 30, more preferably 8 to 24, and may be 8 to 18 in one embodiment. Preferred examples of fatty acids are caprylic acid, 2-ethylhexanoic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, lignoceric acid, elaidic acid, d. Examples thereof include leostearic acid, arachidic acid, elaidic acid, behenic acid, erucic acid, lignoceric acid, and mixtures thereof. As a mixture containing two or more kinds of fatty acids, fatty acids derived from natural fats and oils may be used. Examples of fatty acids derived from natural fats and oils include coconut oil fatty acids, palm kernel oil fatty acids, palm oil fatty acids, millet oil fatty acids, tall oil fatty acids, corn oil fatty acids, rapeseed oil fatty acids, olive oil fatty acids, sesame oil fatty acids, soybean oil fatty acids, and rice bran. Examples thereof include oil fatty acids, sunflower oil fatty acids, sunflower oil fatty acids, linseed oil fatty acids, fish oil fatty acids, beef fat fatty acids, and mixtures thereof. These fatty acids derived from natural fats and oils are a mixture of two or more kinds of fatty acids having 8 to 24 carbon atoms.

Examples of polybasic acids include succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc., which have 2 to 30 carbon atoms, preferably 4 to 30 carbon atoms. Saturated or unsaturated aliphatic dicarboxylic acids of linear or branched chains (the position of the unsaturated bond in the unsaturated aliphatic hydrocarbon group is arbitrary); propantricarboxylic acid, butanetricarboxylic acid, pentantricarboxylic acid, hexanetricarboxylic acid. Linear or branched saturated or unsaturated aliphatic tricarboxylic acids such as acids, heptanetricarboxylic acids, octanetricarboxylic acids, nonantricarboxylic acids, decantricarboxylic acids (the position of unsaturated bonds in unsaturated aliphatic hydrocarbon groups is arbitrary). ); Saturated or unsaturated aliphatic tetracarboxylic acids of straight or branched chains (the position of the unsaturated bond in the unsaturated aliphatic hydrocarbon group is arbitrary) and the like can be mentioned.

As the base oil (A1), one or more ester-based base oils selected from the above (a) to (g) can be used. As the base oil (A1), one kind of ester-based base oil may be used alone, or two or more kinds of ester-based base oils may be used in combination.

Specific examples of the base oil (A1) include esters of monohydric alcohols such as butyl stearate and octyl laurate with monobasic acids; ditridecylglutarate, bis (2-ethylhexyl) adipate, diisodecyl adipate, and ditridecyl. Esters of monohydric alcohols and dibasic acids such as adipate, bis (2-ethylhexyl) sebacate, bis (2-ethylhexyl) azereate; Examples thereof include esters of polyhydric alcohols and monobasic acids such as pentaerythritol-2-ethylhexanoate and pentaerythritol pelargonate; and polyesters such as trimellitic acid ester.

As the base oil (A1), an ester of a polyhydric alcohol and a monobasic acid (above (b)), an ester of a monohydric alcohol and a polybasic acid (above (c)), or a combination thereof is preferably used. be able to.
Preferred examples of the ester (b) of the polyhydric alcohol and the monobasic acid are one or more aliphatic polys selected from trimethylolalkane (for example, trimethylolpropane, trimethylolbutane, etc.), erythritol, and pentaerythritol. Examples thereof include an ester of a valent alcohol and one or more fatty acids having 6 to 30 carbon atoms, preferably 8 to 24 carbon atoms.
Preferred examples of the ester (c) of a monohydric alcohol and a polybasic acid include octanol, 2-ethylhexyl alcohol, nonanol, decanol, isodecanol, undecanol, dodecanol, tridecanol, tetradecanol, hexadecanol, octadecanol and the like. One or more aliphatic monoalcohols having 8 to 18 carbon atoms and one or more kinds of fats having 4 to 10 carbon atoms such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Diesters with group dicarboxylic acids can be mentioned.

Kinematic viscosity at 100 ° C. of the base oil (A1) is preferably 2 to 10 mm ² / s, more preferably from 3 to 10 mm ² / s, may be 8 to 10 mm ² / s in one embodiment. When the kinematic viscosity of the base oil (A1) at 100 ° C. is within the above range, fatigue resistance can be further enhanced. In the present specification, the "kinematic viscosity at 100 ° C." means the kinematic viscosity at 100 ° C. defined in ASTM D-445.

The pour point of the base oil (A1) is not particularly limited, but is preferably −20 ° C. or lower, more preferably −30 ° C. or lower, and particularly preferably −40 ° C. or lower. When the pour point of the base oil (A1) is equal to or less than the above upper limit value, it is possible to improve the low temperature startability and the fuel efficiency immediately after the start.

The hydroxyl value of the base oil (A1) is preferably 2.0 to 20.0 mgKOH / g, more preferably 3.0 to 17.0 mgKOH / g, and 9.0 to 17.0 mgKOH / g in one embodiment. Can be g. When the hydroxyl value of the base oil (A1) is at least the above lower limit value, the adsorptivity of the base oil molecules to the sliding surface is enhanced, so that the oil film thickness on the sliding surface can be increased. Further, when the hydroxyl value of the base oil (A1) is not more than the above upper limit value, the lipophilicity of the base oil (A1) is enhanced, so that the storage stability of the composition can be enhanced. In the present specification, the hydroxyl value of the base oil (A1) means the hydroxyl value measured by the potentiometric titration method in accordance with JIS K0070.

The acid value of the base oil (A1) is preferably 0 to 3.0 mgKOH / g, more preferably 0 to 1.5 mgKOH / g, and may be 0 to 0.55 mgKOH / g in one embodiment. When the acid value of the base oil (A1) is not more than the above upper limit value, it becomes possible to enhance the oxidative stability. In the present specification, the acid value of the base oil (A1) means the acid value measured by the potentiometric titration method in accordance with JIS K0070.

(A) The content of the base oil (A1) in the lubricating oil base oil (total base oil) is 0.5 to 25.0% by mass based on the total amount of the base oil, preferably 1.0 to 20.0. It may be 3 to 15% by weight in one embodiment and 4 to 12% by weight in another embodiment. When the content of the base oil (A1) is within the above range, the fatigue resistance can be enhanced.

As the base oil (A2), one or more types of API base oil classification group II base oil (hereinafter, may be simply referred to as "API group II base oil") or one or more types of API base oil classification group III base oil. (Hereinafter, it may be simply referred to as "API group III base oil"), or one or more API base oil classification group IV base oils (hereinafter, may be simply referred to as "API group IV base oil"), or. A mixture thereof can be used without particular limitation. The API group II base oil is a mineral oil-based base oil having a sulfur content of 0.03% by mass or less, a saturation content of 90% by mass or more, and a viscosity index of 80 or more and less than 120. The API group III base oil is a mineral oil-based base oil having a sulfur content of 0.03% by mass or more, a saturation content of 90% by mass or more, and a viscosity index of 120 or more. The API Group IV base oil is a poly-α-olefin base oil. As the base oil (A2), one kind of base oil may be used alone, or two or more kinds of base oils may be used in combination. In a mixed base oil containing two or more kinds of base oils, the API base oil classifications of those base oils may be the same or different from each other. As the base oil (A2), it is preferable to use one or more API group III base oils, one or more API group IV base oils, or a mixture thereof.

As the mineral oil-based base oil, solvent desorption, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining of the lubricating oil distillate obtained by atmospheric distillation and vacuum distillation of crude oil are carried out. , Paraffin-based or naphthen-based mineral oil-based base oils, which are obtained by appropriately combining one or more kinds of refining means such as sulfuric acid washing and white clay treatment. API Group II base oils and Group III base oils are usually produced through a hydrocracking process. Further, as the mineral oil-based base oil, a wax isomerized base oil, a base oil produced by a method of isomerizing GTL WAX (gas to liquid wax), or the like can also be used.

Examples of the API group IV base oil include ethylene-propylene copolymers, polybutenes, 1-octene oligomers, 1-decene oligomers, and hydrides thereof.

The kinematic viscosity of the base oil (A2) at 100 ° C. is preferably 1.9 to 10.0 mm ² / s, more preferably 2.5 to 7.5 mm ² / s. When the kinematic viscosity of the base oil (A2) at 100 ° C. is equal to or higher than the above lower limit value, the fatigue resistance can be further improved. Further, when the kinematic viscosity of the base oil (A2) at 100 ° C. is not more than the above upper limit value, it is possible to improve fuel efficiency.

The content of the base oil (A2) in the component (A) component (total base oil) is preferably 75.0 to 99.5% by mass, more preferably 80.0 to 99.0% by mass based on the total amount of the base oil. It can be 85-97% by mass in one embodiment and 88-96% by mass in yet another embodiment. When the content of the base oil (A2) is within the above range, the fatigue resistance can be further enhanced.

In one embodiment, the (A) lubricating oil base oil is, in addition to the base oil (A1) and the base oil (A2), the API base oil classification group I base oil (hereinafter referred to as "API group I base oil"). ), Or the API base oil classification group V (hereinafter, may be referred to as "API group V base oil") base oil other than the ester-based base oil, or a combination thereof may be further included. .. The API Group I base oil is a mineral oil-based base oil having a sulfur content of more than 0.03% by mass and / or a saturation content of less than 90% by mass and a viscosity index of 80 or more and less than 120. Examples of the API group V base oil other than the ester-based base oil include alkylbenzene, alkylnaphthalene, polyoxyalkylene glycol, dialkyldiphenyl ether, polyphenyl ether, and mixtures thereof.
However, the total content of the base oil (A1) and the base oil (A2) in the component (A) component (total base oil) is preferably 95 to 100% by mass, more preferably 99 to 100, based on the total amount of the base oil. It is mass%. In one embodiment, the (A) lubricating oil base oil comprises a base oil (A1) and a base oil (A2). When the total content of the base oil (A1) and the base oil (A2) in all the base oils is at least the above lower limit value, the fatigue resistance can be further improved.

(A) The kinematic viscosity of the lubricating oil base oil (total base oil) at 100 ° C. is preferably 2.5 to 7.5 mm ² / s, more preferably 2.9 to 7.0 mm ² / s. 4.0~6.5mm in embodiments 3.2~6.5mm ² / s, in another exemplary embodiment ² / s, ^4.0~5.5mm in yet another embodiment ² / Can be s. When the kinematic viscosity of all the base oils at 100 ° C. is not more than the above upper limit value, it is possible to improve fuel efficiency. Further, when the kinematic viscosity of all the base oils at 100 ° C. is equal to or higher than the above lower limit value, the fatigue resistance can be further improved.

(A) The kinematic viscosity of the lubricating oil base oil (total base oil) at 40 ° C. is preferably 8.0 to 40.0 mm ² / s, more preferably 10.0 to 35.0 mm ² / s. 15.0~30.0mm in embodiments 12.3~30.0mm ² / s, in another exemplary embodiment ² / s, ^15.0~25.0mm in yet another embodiment ² / Can be s. When the kinematic viscosity of all the base oils at 40 ° C. is not more than the above upper limit value, it is possible to improve fuel efficiency. Further, when the kinematic viscosity of all the base oils at 40 ° C. is equal to or higher than the above lower limit value, the fatigue resistance can be further improved. In the present specification, the "kinematic viscosity at 40 ° C." means the kinematic viscosity at 40 ° C. defined in ASTM D-445.

(A) The viscosity index of the lubricating oil base oil (total base oil) is preferably 100 or more, more preferably 105 or more, still more preferably 110 or more, particularly preferably 115 or more, and most preferably 120 or more. When the viscosity index is at least the above lower limit value, it is possible to improve the viscosity-temperature characteristics and wear prevention property of the gear oil composition, and it is also possible to further improve fuel efficiency. In the present specification, the viscosity index means a viscosity index measured in accordance with JIS K 2283-1993.

(A) The content of sulfur in the lubricating oil base oil (total base oil) is preferably 0.03 mass% (300 mass ppm) or less, more preferably 50 mass ppm or less, particularly from the viewpoint of oxidative stability. It is preferably 10 mass ppm or less, and may be 1 mass ppm or less.

The content of the component (A) (total base oil) in the gear oil composition is usually 75 to 98% by mass, preferably 80 to 95% by mass, based on the total amount of the composition, and is 81 to 81 to 95% by mass in one embodiment. It can be 91% by mass.

<(B) Ethylene-α-olefin copolymer>
The gear oil composition of the present invention comprises (B) ^{an ethylene-α-olefin copolymer having a kinematic viscosity at 100 ° C. of 500 to 3000 mm 2} / s (hereinafter, may be referred to as “component (B)”). , 1.0 to 10.0% by mass based on the total amount of the composition.

The component (B) is a copolymer of ethylene and one or more α-olefins. As the component (B), one kind of ethylene-α-olefin copolymer may be used alone, or two or more kinds of ethylene-α-olefin copolymers may be used in combination. In the component (B), the α-olefin copolymerized with ethylene has preferably 3 to 20 carbon atoms, more preferably 3 to 10 carbon atoms. Preferred examples of the α-olefin include propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-octene, 1-decene and the like, and among these, propylene is particularly preferable.

The content of the ethylene repeating unit in the ethylene-α-olefin copolymer is preferably 15 to 85 mol%, more preferably 20 to 80 mol%, based on the total amount of the repeating unit of the copolymer (100 mol%). .. The arrangement of the monomers in the copolymer is not particularly limited, and may be, for example, a random copolymer, for example, an alternating copolymer, or, for example, a block copolymer. You may.

(B) a kinematic viscosity at 100 ° C. of component is 500 to 3,000 mm ² / s, preferably 500~2200mm ² / s. When the kinematic viscosity of the component (B) at 100 ° C. is within the above range, it is possible to improve shear stability, fatigue resistance, and fuel efficiency. In one preferred embodiment, the 100 ° C. kinematic viscosity of component (B) ^{can be 1500-3000 mm 2} / s. When the kinematic viscosity of the component (B) at 100 ° C. is within the above range, fatigue resistance can be further enhanced. In another preferred embodiment, the 100 ° C. kinematic viscosity of component (B) ^{can be 500-1000 mm 2} / s. When the kinematic viscosity of the component (B) at 100 ° C. is within the above range, it is possible to improve fuel efficiency.

The number average molecular weight of the component (B) is preferably 2000 to 8000, more preferably 3000 to 7200, and may be 5000 to 7200 in one embodiment. When the number average molecular weight of the component (B) is not more than the above upper limit value, the shear stability can be further improved. Further, when the number average molecular weight of the component (B) is at least the above lower limit value, a better effect of improving the viscosity index can be obtained. In the present specification, the number average molecular weight of the component (B) is gel permeation chromatography (GPC) (device: Alliance 2695 (manufactured by Waters), column: two GMHHR-M (manufactured by THF) in this order from the upstream side. Connected in series, eluent (solvent): tetrahydrofuran, injection volume: 100 μL, sample concentration: 2.0% by mass, flow velocity: 1 mL / min, temperature: 25 ° C., detector: differential refractometer (RI) detector) It means the number average molecular weight in terms of standard polystyrene to be measured.

The content of the component (B) in the gear oil composition is 1.0 to 10.0% by mass, preferably 1.5 to 9.5% by mass, based on the total amount of the composition, and is one embodiment. It can be 3.0 to 7.0% by mass. When the content of the component (B) is equal to or higher than the above lower limit value, fatigue resistance can be improved, and the traction coefficient can be reduced to a low slip speed region to improve fuel efficiency. .. Further, when the content of the component (B) is not more than the above upper limit value, the fatigue resistance can be enhanced.

<(C) Dithiophosphate triester compound having a carboxy group>
The gear oil composition of the present invention contains (C) a dithiophosphate triester compound having a carboxy group (hereinafter, may be referred to as “component (C)”) in an amount of 0.1 to 1.5 based on the total amount of the composition. Contains% by mass.

As the component (C), a compound represented by the following general formula (1) can be preferably used.

（一般式（１）中、Ｒ^１及びＲ^２はそれぞれ独立に炭素数３〜１８のアルキル基、炭素数５〜１２のシクロアルキル基、炭素数６〜７のシクロアルキルメチル基、炭素数１０〜１１のビシクロアルキルメチル基、炭素数１０〜１１のトリシクロアルキルメチル基、フェニル基、若しくは炭素数７〜２４のアルキルフェニル基、又は相互に結合して２，２−ジメチルプロパン−１，３−ジイル基を表し、Ｒ^３は水素原子またはメチル基を表す。）

(In the general formula (1), R ¹ and R ² are independently an alkyl group having 3 to 18 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, a cycloalkylmethyl group having 6 to 7 carbon atoms, and 10 carbon atoms, respectively. ~ 11 bicycloalkylmethyl groups, 10-11 carbon tricycloalkylmethyl groups, phenyl groups, or 7-24 carbons alkylphenyl groups, or interconnected 2,2-dimethylpropane-1,3 -Represents a diyl group, R ³ represents a hydrogen atom or a methyl group.)

For R ¹ and R ² , the alkyl group having 3 to 18 carbon atoms may be a linear alkyl group or a branched chain alkyl group. Preferred examples of an alkyl group having 3 to 18 carbon atoms include a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a hexyl group, a heptyl group, and a 3-heptyl group. Octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, 2-ethylbutyl group, 1-methylpentyl group, 1 , 3-Dimethylbutyl group, 1,1,3,3-tetramethylbutyl group, 1-methylhexyl group, isoheptyl group, 1-methylheptyl group, 1,1,3-trimethylhexyl group, and 1-methylun A decyl group and the like can be mentioned. Of these, an isopropyl group, an isobutyl group, or a 2-ethylhexyl group is particularly preferable.

For R ¹ and R ² , preferred examples of the cycloalkyl group having 5 to 12 carbon atoms include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and a cyclododecyl group. Among these, a cyclopentyl group or a cyclohexyl group is preferable, and a cyclohexyl group is particularly preferable.

For R ¹ and R ² , the cycloalkylmethyl group having 6 to 7 carbon atoms is a cyclopentylmethyl group or a cyclohexylmethyl group, preferably a cyclohexylmethyl group.

For R ¹ and R ² , a decalynyl methyl group can be mentioned as a preferable example of the bicycloalkylmethyl group having 10 to 11 carbon atoms.

Regarding R ¹ and R ² , preferred examples of the tricycloalkylmethyl group having 10 to 11 carbon atoms include a group represented by the following general formula (2) or (3).

For R ¹ and R ² , preferred examples of alkylphenyl groups include methylphenyl group, dimethylphenyl group, trimethylphenyl group, ethylphenyl group, isopropylphenyl group, tert-butylphenyl group, di-tert-butylphenyl group, And 2,6-di-tert-butyl-4-methylphenyl group.

R ¹ and R ² may be the same group or a combination of two or more different groups. As R ¹ and R ² , an alkyl group having 3 to 18 carbon atoms, a cycloalkyl group having 5 to 6 carbon atoms, or an alkylphenyl group having 7 to 18 carbon atoms is preferable, and an alkyl group having 3 to 18 carbon atoms is particularly preferable. preferable.

The compound of the general formula (1) can be produced, for example, by the reaction represented by the following general formula (4).

一般式（４）で表される、アクリル酸またはメタクリル酸とジチオリン酸ジエステルとの反応は、例えばトルエン等の有機溶媒中で又はｎｅａｔ（無溶媒条件）で行うことができ、反応温度は例えば７０〜８０℃、反応時間は例えば４〜５時間とすることができる。

The reaction of acrylic acid or methacrylic acid and dithiophosphodiester represented by the general formula (4) can be carried out in an organic solvent such as toluene or in neat (solvent-free condition), and the reaction temperature is, for example, 70. The reaction time can be, for example, 4 to 5 hours at -80 ° C.

The content of the component (C) in the gear oil composition is 0.05 to 1.50% by mass, preferably 0.10 to 1.00% by mass, based on the total amount of the composition, and is one embodiment. It can be 0.10 to 0.35% by mass. When the content of the component (C) is at least the above lower limit value, the extreme pressure property can be enhanced. Further, when the content of the component (C) is not more than the above upper limit value, it is possible to improve the oxidative stability, and it is possible to reduce the traction coefficient to the low slip speed region and improve the fuel efficiency. Become.

<(D) Metal-based cleaning agent>
In one preferred embodiment, the gear oil composition may further comprise (D) a metal-based cleaning agent (hereinafter sometimes referred to as "component (D)"). As the component (D), a metal-based cleaning agent known in the field of lubricating oil can be used without particular limitation, and for example, one selected from alkaline earth metal phenate, alkaline earth metal sulfonate, alkaline earth metal salicylate and the like. The above metal-based cleaning agents can be preferably used. As the component (D), one kind of metal-based cleaning agent may be used alone, or two or more kinds of metal-based cleaning agents may be used in combination. Calcium or magnesium is preferable as the alkaline earth metal. In one embodiment, calcium sulfonate and / or calcium salicylate can be preferably used as component (D).

A preferred example of the alkaline earth metal phenate cleaning agent is a hyperbasic salt of the alkaline earth metal salt of the compound represented by the following general formula (5). Calcium or magnesium is preferable as the alkaline earth metal.

In the general formula (5), R ⁴ represents a linear or branched chain having 6 to 21 carbon atoms, a saturated or unsaturated alkyl group or an alkenyl group, and a represents the degree of polymerization and is an integer of 1 to 10. A represents a sulfide (-S-) group or a methylene (-CH _2- ) group, and b represents an integer of 1 to 3. Note R ⁴ may be a combination of two or more different groups.

The number of carbon atoms of ^{R 4} in the general formula (5) is preferably 6 to 18, more preferably 9 to 15. When ^{the carbon number of R 4} is at least the above lower limit value, the solubility in the base oil can be enhanced. Further, when ^{the carbon number of R 4} is not more than the above upper limit value, the production becomes easy.

The degree of polymerization a in the general formula (5) is preferably 1 to 3. When the degree of polymerization a is within this range, the heat resistance can be enhanced.

Preferred examples of the alkaline earth metal sulfonate detergent include an alkaline earth metal salt of an alkyl aromatic sulfonic acid obtained by sulfonated an alkyl aromatic compound, or a basic salt or a perbasic salt thereof. Can be done. The weight average molecular weight of the alkyl aromatic compound is preferably 400-1500. Calcium or magnesium is preferable as the alkaline earth metal.
Examples of alkyl aromatic sulfonic acids include so-called petroleum sulfonic acids and synthetic sulfonic acids. Examples of the petroleum sulfonic acid referred to here include sulfonated alkyl aromatic compounds of the lubricating oil distillate of mineral oil, so-called mahoganic acid, which is produced as a by-product during the production of white oil. Further, as an example of synthetic sulfonic acid, it has a linear or branched alkyl group obtained by recovering a by-product in an alkylbenzene production plant which is a raw material of a detergent, or by alkylating benzene with polyolefin. Examples thereof include sulfonated alkylbenzenes. As another example of the synthetic sulfonic acid, an alkylnaphthalene such as dinonylnaphthalene sulfonated can be mentioned. Further, as the sulfonate agent for sulfonated these alkyl aromatic compounds, known sulfonate agents such as fuming sulfuric acid and anhydrous sulfuric acid can be used without particular limitation.

Preferred examples of the alkaline earth metal salicylate detergent include alkaline earth metal salicylate or a basic salt or a perbasic salt thereof. Calcium or magnesium is preferable as the alkaline earth metal. A preferable example of the alkaline earth metal salicylate is a compound represented by the following general formula (6).

In the general formula (6), R ⁵ independently represents an alkyl group or an alkenyl group having 14 to 30 carbon atoms, M represents an alkaline earth metal, c represents 1 or 2, and is preferably 1. When c = 2, R ⁵ may be a combination of different groups.

As a preferable form of the alkaline earth metal salicylate cleaning agent, alkaline earth metal salicylate having c = 1 in the above general formula (6) or a basic salt or a perbasic salt thereof can be mentioned.

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

The component (D) may be superbasified with a carbonate (for example, an alkaline earth metal carbonate such as calcium carbonate or magnesium carbonate), and a borate (for example, an alkali such as calcium borate or magnesium borate). It may be hyperbasified with earth metal borate.).
The method for obtaining a metal-based cleaning agent superbasified with alkaline earth metal carbonate is not particularly limited, but for example, in the presence of carbon dioxide gas, a metal-based cleaning agent (for example, alkaline earth metal phenate, etc.) It can be obtained by reacting a neutral salt of an alkaline earth metal sulfonate, an alkaline earth metal salicylate, etc. with a base of an alkaline earth metal (for example, an alkali earth metal hydroxide, an oxide, etc.). ..
The method for obtaining a metal-based cleaning agent superbasified with alkaline earth metal borate is not particularly limited, but is metal-based in the presence of borate or borate anhydride and optionally borate. A neutral salt of a cleaning agent (for example, alkaline earth metal phenate, alkaline earth metal sulfonate, alkaline earth metal salicylate, etc.) is used as a base of alkaline earth metal (for example, alkali earth metal hydroxide, oxide, etc.). ) Can be obtained. The boric acid may be orthoboric acid or condensed boric acid (for example, diboric acid, triboric acid, tetraboric acid, metaboric acid, etc.). As the borate, calcium salts or magnesium salts of these boric acids can be preferably used. The borate may be a neutral salt or an acidic salt. One type of boric acid and / or borate may be used alone, or two or more types may be used in combination.

The content of the component (D) in the gear oil composition is preferably 0.1 to 0.5% by mass, more preferably 0.2 to 0.4% by mass as the metal amount based on the total amount of the composition. In one embodiment it can be 0.3-0.4% by weight. When the content of the component (D) is within the above range, it is possible to improve the cleaning performance and the maintainability of the base value, and it is possible to improve the frictional characteristics of the synchronizer ring.

<(E) Nitrogen-containing ashless dispersant>
In one preferred embodiment, the gear oil composition may further comprise (E) a nitrogen-containing ashless dispersant (hereinafter sometimes referred to as "component (E)").

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

As the component (E), the component (E-1) can be particularly preferably used.
Among the components (E-1), examples of the succinimide having at least one alkyl group or alkenyl group in the molecule include compounds represented by the following general formula (7) or (8). ..

In formula (7), R ⁶ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, and d represents an integer of 1 to 5, preferably 2 to 4. The carbon number of R ⁶ is preferably 60 to 350.

In the formula (8), R ⁷ and R ⁸ each independently represent an alkyl group or an alkenyl group having 40 to 400 carbon atoms, and may be a combination of different groups. Further, e represents an integer of 0 to 4, preferably 1 to 4, and more preferably 1 to 3. The carbon number of R ⁷ and R ⁸ is preferably 60 to 350.

^{When the carbon number of R 6 to} R ⁸ in the formulas (7) and (8) is at least the above lower limit value, good solubility in the lubricating oil base oil can be obtained. On the other hand, when the ^{number of carbon atoms of R 6 to} R ⁸ is not more than the above upper limit value, the low temperature fluidity of the gear oil composition can be enhanced.

The alkyl group or alkenyl group (R ^{6 to} R ⁸ ) in the formulas (7) and (8) may be linear or branched, and is preferably an oligomer of an olefin such as propylene, 1-butene, or isobutene. Examples thereof include branched alkyl groups and branched alkenyl groups derived from co-oligomers of ethylene and propylene. Of these, a branched alkyl group or alkenyl group commonly derived from an oligomer of isobutene commonly called polyisobutylene, or a polybutenyl group is most preferable.
Suitable number average molecular weights ^{of alkyl or alkenyl groups (R 6 to} R ⁸ ) in formulas (7) and (8) are 800 to 3500.

A so-called monotype succinimide represented by the formula (7), in which succinic anhydride is added to only one end of the polyamine chain to the succinimide having at least one alkyl group or alkenyl group in the molecule. And the so-called bis-type succinimide represented by the formula (8), in which succinic anhydride is added to both ends of the polyamine chain, are included. The gear oil composition of the present invention may contain either a monotype succinimide or a bis-type succinimide, and both of them may be contained as a mixture. The content of the bis-type succinimide or a modified product thereof in the component (E-1) is preferably 50% by mass or more, more preferably 70, based on the total amount of the component (E-1) (100% by mass). It is mass% or more.

The method for producing succinimide having at least one alkyl group or alkenyl group in the molecule is not particularly limited. The succinimide can be obtained as a condensation reaction product by reacting, for example, an alkyl or alkenyl succinic acid having an alkyl or alkenyl group having 40 to 400 carbon atoms or an anhydride thereof with a polyamine. As the component (E-1), the condensation product may be used as it is, or the condensation product may be converted into a derivative described later and used. The condensation product of alkyl or alkenyl succinic acid or its anhydride and polyamine may be a bis-type succinimide (see general formula (8)) in which both ends of the polyamine chain are imidized. It may be a monotype succinimide (see general formula (7)) in which only one end of the polyamine chain is imidized, or a mixture thereof. Here, the alkenyl succinic anhydride having an alkenyl group having 40 to 400 carbon atoms can be obtained, for example, by reacting an olefin having 40 to 400 carbon atoms with maleic anhydride at 100 to 200 ° C. Further, by further subjecting the alkenyl succinic anhydride to a hydrogenation reaction, an alkyl succinic anhydride having an alkyl group having 40 to 400 carbon atoms can be obtained. Examples of polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine, and mixtures thereof, and it is preferable to use a polyamine raw material containing at least one selected from these. it can. The polyamine raw material may or may not further contain ethylenediamine, but from the viewpoint of enhancing the performance of the condensation product or its derivative as a dispersant, the content of ethylenediamine in the polyamine raw material is the total amount of polyamine. By reference, it is preferably 0 to 10% by mass, more preferably 0 to 5% by mass. The succinimide obtained as a condensation reaction product of an alkyl or alkenyl succinic acid having an alkyl or alkenyl group having 40 to 400 carbon atoms or an anhydride thereof and a mixture of two or more kinds of polyamines is described in the general formula (7) or. (8) is a mixture of compounds having different d or e.

The weight average molecular weight of the component (E-1) is 1000 to 20000, more preferably 2000 to 20000, still more preferably 3000 to 15000, and in one embodiment it may be 4000 to 9000.

Among the components (E-2), examples of benzylamine having at least one alkyl group or alkenyl group in the molecule include a compound represented by the following formula (9).

In formula (9), R ⁹ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, and f represents an integer of 1 to 5, preferably 2 to 4. The carbon number of R ⁹ is preferably 60 to 350.

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

As an example of the polyamine having at least one alkyl group or alkenyl group in the molecule among the components (E-3), a compound represented by the following formula (10) can be mentioned.

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

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

Examples of the modified product (modified compound) in the components (E-1) to (E-3) include (i) a modified compound by an oxygen-containing organic compound, (ii) a boric acid-modified compound, and (iii) a phosphoric acid modification. Examples thereof include a compound, (iv) a sulfur-modified compound, and (v) a modified compound obtained by combining two or more of these modifications.
(I) The modified compound by the oxygen-containing organic compound is a fatty acid in the above-mentioned succinateimide, benzylamine or polyamine having at least one alkyl group or alkenyl group in the molecule (hereinafter referred to as "the above-mentioned nitrogen-containing compound"). Monocarboxylic acids having 1 to 30 carbon atoms, polycarboxylic acids having 2 to 30 carbon atoms (for example, oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc.), these anhydrides or ester compounds, carbon atoms, etc. It is a modified compound in which some or all of the remaining amino groups and / or imino groups are neutralized or amidated by the action of 2 to 6 alkylene oxides or hydroxy (poly) oxyalkylene carbonates.
(Ii) The boron-modified compound is a modified compound in which a part or all of the remaining amino groups and / or imino groups are neutralized or amidated by allowing boric acid to act on the above-mentioned nitrogen-containing compound.
(Iii) The phosphoric acid-modified compound is a modified compound in which a part or all of the remaining amino groups and / or imino groups are neutralized or amidated by allowing phosphoric acid to act on the above-mentioned nitrogen-containing compound. ..
(Iv) The sulfur-modified compound is a modified compound obtained by allowing a sulfur compound to act on the above-mentioned nitrogen-containing compound.
(V) The modified compound by the combination of two or more kinds of modifications is applied by combining the above-mentioned nitrogen-containing compound with two or more kinds of modifications selected from modification with an oxygen-containing organic compound, boron modification, phosphoric acid modification, and sulfur modification. Can be obtained by
Among these derivatives (i) to (v), boric acid-modified compounds of alkenyl succinimide, particularly bis-type boric acid-modified compounds of alkenyl succinimide can be preferably used.

When the gear oil composition contains the component (E), the content thereof is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 3.0% by mass based on the total amount of the composition. Yes, it can be 0.1-1.0% by weight in one embodiment. When the content of the component (E) is at least the above lower limit value, the caulking resistance of the gear oil composition can be sufficiently improved and the solubility of the additive can be enhanced. Further, when the content of the component (E) is not more than the above upper limit value, it becomes possible to maintain higher fuel efficiency.

In one embodiment, component (E) may be a boric acid-modified succinimide ashless dispersant. In another embodiment, component (E) is a combination of one or more boric acid-modified succinimide ashless dispersants and one or more unboric acid-modified succinimide ashless dispersants. You may. In another embodiment, component (E) may be one or more unboric acid-modified succinimide ashless dispersants.

<(F) Sulfur-containing extreme pressure agent>
In one preferred embodiment, the gear oil composition may further comprise one or more sulfur-containing extreme pressure agents (hereinafter sometimes referred to as "component (F)") other than the component (C). Examples of sulfur-containing extreme pressure agents other than the component (C) include thiadiazol compounds, sulfide oils and fats, sulfide fatty acids, sulfide esters, sulfide olefins, dihydrocarbyl (poly) sulfate, alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, and di Known sulfur-containing extreme pressure agents and phosphorus-sulfur-based additives such as alkylthiodipropionate compounds, sulfide ore oils, zinc dithiocarbamate compounds, molybdenum dithiocarbamate compounds, zinc dithiophosphate compounds, molybdenum dithiophosphate compounds can be mentioned. One or more additives selected from these can be preferably used as the component (F). As the sulfur-containing additive, one type may be used alone, or two or more types may be used in combination. The phosphorus-sulfur additive also contributes to the content of the component (G) described later. As will be described later, from the viewpoint of reducing the molybdenum content in the composition, the component (F) includes thiadiazole compound, sulfide oil and fat, sulfide fatty acid, sulfide ester, olefin sulfide, dihydrocarbyl (poly) sulfuride, and alkylthiocarbamoyl compound. , Thiocarbamate compound, thioterpen compound, dialkylthiodipropionate compound, sulfide ore oil, zinc dithiocarbamate compound, and one or more additives selected from zinc dithiophosphate compound are preferably used.

Preferred examples of the thiadiazole compound include a 1,3,4-thiadiazole compound represented by the following general formula (11), a 1,2,4-thiadiazole compound represented by the following general formula (12), and the following general formula. The 1,2,3-thiadiazole compound represented by (13) can be mentioned.

（一般式（１１）〜（１３）中、Ｒ^１１及びＲ^１２は同一でも異なっていてもよく、それぞれ独立に水素原子または炭素数１〜２０のヒドロカルビル基を表し；ｈ及びｉは同一でも異なっていてもよく、それぞれ独立に０〜８の整数を表す。）

(In the general formulas (11) to (13), R ¹¹ and R ¹² may be the same or different, and each independently represents a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms; h and i are the same or different. It may be, and each independently represents an integer of 0 to 8.)

Sulfurized fats and oils are products obtained by reacting sulfur or sulfur-containing compounds with fats and oils (lard oil, whale oil, vegetable oil, fish oil, etc.). The sulfur content in the sulfide fat and oil is not particularly limited, but is usually 5 to 30% by weight.

As the sulfide fatty acid, a product obtained by sulfurizing an unsaturated fatty acid by an arbitrary method can be used, and examples thereof include oleic acid sulfide.
As the sulfide ester, an unsaturated fatty acid ester (for example, a product obtained by reacting an unsaturated fatty acid (for example, oleic acid, linoleic acid, or a fatty acid extracted from the above-mentioned animal and vegetable fats and oils) with various alcohols) is optional. The product obtained by sulphurizing by the method of the above can be used, and examples thereof include methyl oleate sulfide, rice bran sulfide fatty acid octyl and the like.

Examples of the olefin sulfide include a compound represented by the following general formula (14). This compound can be obtained by reacting an olefin having 2 to 15 carbon atoms or a 2 to tetramer thereof with a sulfurizing agent such as sulfur or sulfur chloride. As the olefin, propylene, isobutene, diisobutene and the like can be preferably used.

（一般式（１４）中、Ｒ^１３は炭素数２〜１５のアルケニル基を表し、Ｒ^１４は炭素数２〜１５のアルキル基又はアルケニル基を表し、ｊは１〜８の整数を示す。）

(In the general formula (14), R ¹³ represents an alkenyl group ^{having 2 to 15 carbon atoms, R 14} represents an alkyl group or an alkenyl group having 2 to 15 carbon atoms, and j represents an integer of 1 to 8.)

Dihydrocarbyl (poly) sulfide is a compound represented by the following general formula (15). Here, when R ¹⁵ and R ¹⁶ are alkyl groups, they are sometimes referred to as alkyl sulfides.

（一般式（１５）中、Ｒ^１５及びＲ^１６は同一でも異なっていてもよく、それぞれ独立に炭素数１〜２０のアルキル基（直鎖でも分岐鎖でもよく、環状構造を有していてもよい。）、炭素数６〜２０のアリール基、炭素数７〜２０のアルキルアリール基、又は炭素数７〜２０のアリールアルキル基を表し、ｋは１〜８の整数を表す。）

(In the general formula (15), R ¹⁵ and R ¹⁶ may be the same or different, and each has an independently alkyl group having 1 to 20 carbon atoms (either a straight chain or a branched chain, and may have a cyclic structure. It represents an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms, and k represents an integer of 1 to 8 carbon atoms.)

Examples of the alkylthiocarbamoyl compound include a compound represented by the following general formula (16).

（一般式（１６）中、Ｒ^１７〜Ｒ^２０は同一でも異なっていてもよく、それぞれ独立に炭素数１〜２０のアルキル基を表し、ｌは１〜８の整数を表す。）

(In the general formula (16), R ^{17 to} R ²⁰ may be the same or different, and each independently represents an alkyl group having 1 to 20 carbon atoms, and l represents an integer of 1 to 8).

Examples of the alkylthiocarbamate compound include the compound represented by the following general formula (17).

（一般式（１７）中、Ｒ^２１〜Ｒ^２４は同一でも異なっていてもよく、それぞれ炭素数１〜２０のアルキル基を示し、Ｒ^２５は炭素数１〜１０のアルキレン基を示す。）

(In the general formula (17), R ^{21 to} R ²⁴ may be the same or different, and each represents an alkyl group having 1 to 20 carbon atoms, and R ²⁵ represents an alkylene group having 1 to 10 carbon atoms.)

Examples of the thioterpen compound include a reaction product of phosphorus pentasulfide and pinene.
Examples of the dialkylthiodipropionate compound include dilaurylthiodipropionate and distearylthiodipropionate.

Sulfide mineral oil is a substance obtained by dissolving elemental sulfur in mineral oil. The mineral oil used for the sulfide mineral oil is not particularly limited, and as an example, a known refining treatment is appropriately combined with a lubricating oil distillate obtained by subjecting crude oil to atmospheric distillation and vacuum distillation. Examples thereof include paraffin-based mineral oil and naphthen-based mineral oil refined by application. Further, as the elemental sulfur, any form such as lumpy, powdery, molten liquid and the like may be used. The sulfur content in the sulfide ore oil is not particularly limited, but is usually 0.05 to 1.0% by weight based on the total amount of the sulfide ore oil.

As the zinc dithiocarbamate compound, a compound represented by the following general formula (18) can be used, and as the molybdenum dithiocarbamate compound, a compound represented by the following general formula (19) can be used.

（一般式（１８）中、Ｒ^２６〜Ｒ^２９は同一でも異なっていてもよく、それぞれ独立に炭素数１以上のヒドロカルビル基を表す。）

(In the general formula (18), R ^{26 to} R ²⁹ may be the same or different, and each independently represents a hydrocarbyl group having 1 or more carbon atoms.)

（一般式（１９）中、Ｒ^３０〜Ｒ^３３は同一でも異なっていてもよく、それぞれ独立に炭素数１以上のヒドロカルビル基を表し、Ｘ^１〜Ｘ^４はそれぞれ独立に酸素原子又は硫黄原子を表す。）

(In the general formula (19), R ^{30 to} R ³³ may be the same or different, and each independently represents a hydrocarbyl group having 1 or more carbon atoms, and X ^{1 to} X ⁴ independently represent an oxygen atom or a sulfur atom. Represent.)

As the zinc dithiophosphate compound, a compound represented by the following general formula (20) can be used.

（一般式（２０）中、Ｒ^３４〜Ｒ^３７は同一でも異なっていてもよく、それぞれ独立に炭素数３〜１８のヒドロカルビル基を表す。）

(In the general formula (20), R ^{34 to} R ³⁷ may be the same or different, and each independently represents a hydrocarbyl group having 3 to 18 carbon atoms.)

As an example of the molybdenum dithiophosphate compound, a compound represented by the following general formula (21) can be mentioned.

（一般式（２１）中、Ｒ^３８〜Ｒ^４１は同一でも異なっていてもよく、それぞれ独立に炭素数１以上のヒドロカルビル基を表し、Ｘ^５〜Ｘ^８はそれぞれ独立に酸素原子又は硫黄原子を表す。）
一般式（２１）の化合物は２核モリブデン錯体であるが、ジチオリン酸モリブデン化合物は当該形態に限定されない。例えば単核モリブデン錯体や３核以上の多核モリブデン錯体である形態のジチオリン酸モリブデン化合物を用いることも可能である。

(In the general formula (21), R ^{38 to} R ⁴¹ may be the same or different, and each independently represents a hydrocarbyl group having 1 or more carbon atoms, and X ^{5 to} X ⁸ independently represent an oxygen atom or a sulfur atom. Represent.)
The compound of the general formula (21) is a dinuclear molybdenum complex, but the molybdenum dithiophosphate compound is not limited to this form. For example, it is also possible to use a molybdenum dithiophosphate compound in the form of a mononuclear molybdenum complex or a polynuclear molybdenum complex having three or more nuclei.

When the gear oil composition contains the component (F), the content thereof is preferably 0.3 to 2.5% by mass, more preferably 0.5 to 2.0% by mass as the amount of sulfur based on the total amount of the composition. %, Which can be 0.5-1.3% by weight in one embodiment. When the content of the component (F) is at least the above lower limit value, extreme pressure resistance and fatigue resistance can be further enhanced. Further, when the content of the component (F) is not more than the above upper limit value, it becomes possible to further improve the wear resistance, the fatigue resistance, the oxidation stability, and the friction characteristics of the synchronizer ring.

<(G) Phosphorus-containing anti-wear agent>
In one preferred embodiment, the gear oil composition further comprises one or more phosphorus-containing antiwear agents (hereinafter sometimes referred to as "component (G)") other than the component (C) and the component (F). Can include. Examples of the component (G) include the phosphorus-sulfur-based additive described above as the component (F), a compound represented by the following general formula (22), a compound represented by the following general formula (23), and a compound. Phosphorus-containing abrasion inhibitors such as those metal salts and ammonium salts can be mentioned. One type of phosphorus-containing additive may be used alone, or two or more types may be used in combination. When the component (G) contains a sulfur element, the content thereof shall also contribute to the content of the component (F).

（一般式（２２）中、Ｘ^９、Ｘ^１０、及びＸ^１１は、それぞれ独立に酸素原子または硫黄原子を表し；Ｒ^４２は炭素数１〜３０の炭化水素基を表し；Ｒ^４３及びＲ^４４はそれぞれ独立に水素原子または炭素数１〜３０の炭化水素基を表し；Ｒ^４２、Ｒ^４３、及びＲ^４４は同一でも相互に異なっていてもよい。）

(In general formula (22), X ⁹ , X ¹⁰ and X ¹¹ independently represent an oxygen atom or a sulfur atom; R ⁴² represents a hydrocarbon group having 1 to 30 carbon atoms; R ⁴³ and R ^44. Represent each independently a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; R ⁴² , R ⁴³ , and R ⁴⁴ may be the same or different from each other.)

（一般式（２３）中、Ｘ^１２、Ｘ^１３、Ｘ^１４、及びＸ^１５は、それぞれ独立に酸素原子または硫黄原子を表し；Ｒ^４５は炭素数１〜３０の炭化水素基を表し；Ｒ^４６及びＲ^４７はそれぞれ独立に水素原子または炭素数１〜３０の炭化水素基を表し；Ｒ^４５、Ｒ^４６、及びＲ^４７は同一でも相互に異なっていてもよい。）

(In general formula (23), X ¹² , X ¹³ , X ¹⁴ and X ¹⁵ each independently represent an oxygen atom or a sulfur atom; R ⁴⁵ represents a hydrocarbon group having 1 to 30 carbon atoms; R ^46. And R ⁴⁷ independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms; R ⁴⁵ , R ⁴⁶ , and R ⁴⁷ may be the same or different from each other.)

Examples of hydrocarbon groups having 1 to 30 carbon atoms in the general formulas (22) and (23) include alkyl groups, cycloalkyl groups, alkenyl groups, alkyl-substituted cycloalkyl groups, aryl groups, alkyl-substituted aryl groups, and aryls. Alkyl groups and the like can be mentioned. The hydrocarbon group is preferably an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 24 carbon atoms, and in one embodiment, an alkyl group having 3 to 18 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms. It is an aryl group or an alkylaryl group.

Specific examples of the metal forming a metal salt with the phosphorus compound represented by the general formula (22) or (23) include alkali metals such as lithium, sodium, potassium and cesium, calcium, magnesium and barium. Alkali earth metals, heavy metals such as zinc, copper, iron, lead, nickel, silver and manganese. Among these, alkaline earth metals such as calcium and magnesium, zinc, or a combination thereof is preferable.

Examples of the nitrogen-containing compound forming an ammonium salt with the phosphorus compound represented by the general formula (22) or (23) include ammonia, monoamine, diamine, polyamine, and alkanolamine. More specifically, a nitrogen-containing compound represented by the following general formula (24); alkylenediamines such as methylenediamine, ethylenediamine, propylenediamine, and butylenediamine; diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine. Et al., And combinations thereof, etc. can be mentioned.

（一般式（２４）中、Ｒ^４８〜Ｒ^５０はそれぞれ独立に、水素原子、炭素数１〜８のヒドロカルビル基、又はヒドロキシ基を有する炭素数１〜８のヒドロカルビル基を表し；Ｒ^４８〜Ｒ^５０のうち少なくとも１つは炭素数１〜８のヒドロカルビル基、又はヒドロキシ基を有する炭素数１〜８のヒドロカルビル基である。）

(In the general formula (24), R ^{48 to} R ⁵⁰ each independently represent a hydrogen atom, a hydrocarbyl group having 1 to 8 carbon atoms, or a hydrocarbyl group having 1 to 8 carbon atoms having a hydroxy group; R ^{48 to R. At} least one of the 50 is a hydrocarbyl group having 1 to 8 carbon atoms or a hydrocarbyl group having a hydroxy group and having 1 to 8 carbon atoms.)

Among the above-mentioned compounds, a phosphorous acid ester compound and / or a phosphite ester compound can be preferably used as the phosphorus-containing additive, and among them, an alkyl group, an aryl group, or an alkylaryl group having 4 to 18 carbon atoms can be used. A phosphorous acid triester, a phosphite diester, an ammonium salt thereof, or a combination thereof can be particularly preferably used.

When the gear oil composition contains the component (G), the content thereof is preferably 0.05 to 0.25% by mass, more preferably 0.10 to 0.20% by mass as the phosphorus amount based on the total amount of the composition. %, Which can be 0.13 to 0.20% by weight in one embodiment. When the content of the component (G) is at least the above lower limit value, it becomes possible to further improve the wear resistance and fatigue resistance. Further, when the content of the component (G) is not more than the above upper limit value, the extreme pressure resistance and the fatigue resistance can be further improved.

<(H) Oil-based friction modifier>
In one preferred embodiment, the gear oil composition may further comprise (H) an oil-based friction modifier (hereinafter sometimes referred to as "component (H)"). As the component (H), for example, the molecule has a hydrocarbon group having 6 or more carbon atoms and a functional group containing at least one hetero element selected from an oxygen atom, a nitrogen atom, and a sulfur atom, and has 6 carbon atoms. ~ 50 compounds can be used. In one embodiment, an amine compound, a fatty acid ester, a fatty acid amide, a fatty acid, an aliphatic alcohol, an aliphatic ether, a urea having at least one aliphatic hydrocarbyl or an aliphatic hydrocarbylcarbonyl group having 8 to 36 carbon atoms in the molecule. A compound such as a system compound or a hydrazide system compound can be preferably used as the component (H).

Examples of amine-based friction modifiers are aliphatic groups having an alkyl or alkenyl group, preferably a linear alkyl or linear alkenyl group, having 8 to 30, preferably 12 to 24, more preferably 12 to 20 carbon atoms. Amine compounds can be mentioned.

Examples of amide-based friction modifiers include condensation products of straight-chain or branched-chain fatty acids, preferably straight-chain fatty acids, with ammonia, aliphatic monoamines, or aliphatic polyamines.

As an example of the amide-based friction modifier, a fatty acid amide compound having an alkylcarbonyl or alkenylcarbonyl group having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms can be mentioned. The amide compound is, for example, a fatty acid having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms or a acid compound thereof, an aliphatic primary or secondary amine compound, or an aliphatic primary or secondary alkanolamine. It can be obtained by a condensation reaction with a compound or ammonia. The amine compound and the alkanolamine compound preferably have an aliphatic group having 1 to 30 carbon atoms, more preferably an aliphatic group having 1 to 10 carbon atoms, and further preferably an aliphatic group having 1 to 4 carbon atoms. In one embodiment, it has an aliphatic group having 1 or 2 carbon atoms.
Examples of fatty acid amide friction modifiers include lauric acid amides, myristic acid amides, palmitic acid amides, stearic acid amides, oleic acid amides, coconut oil fatty acid amides, synthetic mixed fatty acid amides having 12 to 13 carbon atoms, and the like. Can be done.

Other examples of amide-based friction modifiers include alkyl or alkenyl groups having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms, or alkylcarbonyls or alkenylcarbonyls having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms. Examples thereof include fatty acid hydrazide, aliphatic semicarbazide, aliphatic urea, fatty acid ureide, aliphatic allophanoic acid amide, and derivatives (modified compounds) thereof having a group. Examples of the derivative (modified compound) of the amide-based friction modifier include a boric acid-modified compound obtained by reacting the above-mentioned amide compound with boric acid or a borate.

Examples of the aliphatic urea friction modifier include dodecylurea, tridecylurea, tetradecylurea, pentadecylurea, hexadecylurea, heptadecylurea, octadecylurea, and oleylurea, which have 8 to 30 carbon atoms, preferably 12 carbon atoms. -24, more preferably an aliphatic urea compound having an alkyl or alkenyl group having 12 to 20 carbon atoms, and an acid-modified derivative thereof (acid-modified compound, for example, boric acid-modified compound, etc.) can be mentioned.

Examples of fatty acid hydrazide friction modifiers include dodecanoic acid hydrazide, tridecanoic acid hydrazide, tetradecanoic acid hydrazide, pentadecanoic acid hydrazide, hexadecanoic acid hydrazide, heptadecanoic acid hydrazide, octadecanoic acid hydrazide, oleate hydrazide, erucate hydrazide and the like. Examples thereof include fatty acid hydrazide compounds having an alkylcarbonyl or alkenylcarbonyl group having 8 to 30, preferably 12 to 24 carbon atoms, and acid-modified derivatives thereof (acid-modified compounds such as boric acid-modified compounds).

Other examples of the amide-based friction modifier include an amide compound of an aliphatic hydroxy acid having a hydroxy-substituted alkyl or alkenyl group having 1 to 30 carbon atoms. The amide compound can be obtained, for example, by a condensation reaction between the aliphatic hydroxy acid and an aliphatic primary or secondary amine compound or an aliphatic primary or secondary alkanolamine compound. The hydroxy-substituted alkyl or alkenyl group of the aliphatic hydroxy acid preferably has 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms, and is 1 or 2 in one embodiment. The aliphatic hydroxy acid is preferably a linear aliphatic α-hydroxy acid, and is a glycolic acid in one embodiment. The amine compound and the alkanolamine compound are preferably an aliphatic group having 1 to 30 carbon atoms, more preferably an aliphatic group having 10 to 30 carbon atoms, still more preferably an aliphatic group having 12 to 24 carbon atoms, and particularly preferably. It has an aliphatic group having 12 to 20 carbon atoms.

As another example of the amide-based friction modifier, an amide compound (N-acylated amino acid) of an amino acid and a fatty acid having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms can be mentioned. Examples of N-acylated amino acid friction modifiers include N-acylated N-methylglycine (eg, N-oleoyl-N-methylglycine, etc.).

Examples of fatty acid ester friction modifiers include partial esters in which some hydroxy groups of polyhydric alcohols such as glycerin are esterified with fatty acids having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms. it can.

Examples of the aliphatic alcohol friction modifier include an aliphatic alcohol having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms. Such aliphatic alcohols can be preferably obtained by reducing the carboxy group of the fatty acid.

Examples of the aliphatic ether friction modifier include an alkylene oxide adduct of an aliphatic alcohol obtained by reacting the above aliphatic alcohol compound with an alkylene oxide such as ethylene oxide or propylene oxide or an oligomer thereof. it can.

According to the gear oil composition in the form containing the component (H), when the gear oil composition is used as the manual transmission oil, the reduction of the coefficient of static friction improves the sliding of the synchronizer ring from the synchro cone. At the same time, the resistance when pushing the sleeve teeth into the spline teeth of the floating gear after matching the rotation speeds of the floating gear and the sleeve is reduced, so that the shifting feeling is improved.

When the gear oil composition contains the component (H), the content thereof is preferably 0.05 to 1.00% by mass, more preferably 0.10 to 0.50% by mass based on the total amount of the composition. Yes, it can be 0.12 to 0.40% by weight in one embodiment.

<(I) Antioxidant>
In one preferred embodiment, the gear oil composition may further comprise an antioxidant (hereinafter sometimes referred to as "component (I)"). As the antioxidant, an antioxidant known in the field of lubricating oil, such as a phenolic antioxidant, an aromatic amine-based antioxidant, and a hindered amine-based antioxidant, can be used without particular limitation.

Examples of aromatic amine-based antioxidants include primary aromatic amine compounds such as alkylated α-naphthylamine; and alkylated diphenylamine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, and phenyl-β. -Secondary aromatic amine compounds such as naphthylamine can be mentioned. As the aromatic amine-based antioxidant, alkylated diphenylamine, alkylated phenyl-α-naphthylamine, or a combination thereof can be preferably used.

Examples of hindered amine-based antioxidants include 2,2,6,6-tetraalkylpiperidine derivatives. As the 2,2,6,6-tetraalkylpiperidine derivative, a 2,2,6,6-tetraalkylpiperidine derivative having a substituent at the 4-position is preferable. Further, two 2,2,6,6-tetraalkylpiperidine skeletons may be bonded via their respective 4-position substituents. Further, the N-position of the 2,2,6,6-tetraalkylpiperidine skeleton may be unsubstituted, and the N-position may be substituted with an alkyl group having 1 to 4 carbon atoms. The 2,2,6,6-tetraalkylpiperidine skeleton is preferably a 2,2,6,6-tetramethylpiperidine skeleton.

As the substituents at the 4-position of the 2,2,6,6-tetraalkylpiperidine skeleton, asyloxy group (R ⁵¹ COO-), alkoxy group (R ⁵¹ O-), alkylamino group (R ⁵¹ NH-), Acylamino group (R ⁵¹ CONH-), etc. can be mentioned. R ⁵¹ is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably 1 to 24 carbon atoms, and even more preferably 1 to 20 carbon atoms. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, a cycloalkyl group, an alkylcycloalkyl group, an aryl group, an alkylaryl group, an arylalkyl group and the like.

When two 2,2,6,6-tetraalkylpiperidin skeletons are bonded via their respective 4-position substituents, the substituent is a hydrocarbylenebis (carbonyloxy) group (-OOC-). R ⁵² -COO-), hydrocarbylene diamino group (-HN-R ⁵² -NH-), hydrocarbylenebis (carbonylamino) group (-HNCO-R ⁵² -CONH-), and the like. R ⁵² is preferably a hydrocarbylene group having 1 to 30 carbon atoms, and more preferably an alkylene group.

As the substituent at the 4-position of the 2,2,6,6-tetraalkylpiperidine skeleton, an asyloxy group is preferable. An example of a compound having an asyloxy group at the 4-position of the 2,2,6,6-tetraalkylpiperidine skeleton is an ester of 2,2,6,6-tetramethyl-4-piperidinol and a carboxylic acid. Can be done. Examples of the carboxylic acid include straight-chain or branched-chain aliphatic carboxylic acids having 8 to 20 carbon atoms.

Examples of phenolic antioxidants are 4,4'-methylenebis (2,6-di-tert-butylphenol); 4,4'-bis (2,6-di-tert-butylphenol); 4,4'. -Bis (2-methyl-6-tert-butylphenol); 2,2'-methylenebis (4-ethyl-6-tert-butylphenol); 2,2'-methylenebis (4-methyl-6-tert-butylphenol); 4,4'-butylidenebis (3-methyl-6-tert-butylphenol); 4,4'-isopropyridenebis (2,6-di-tert-butylphenol); 2,2'-methylenebis (4-methyl-6) -Nonylphenol); 2,2'-isobutylidenebis (4,6-dimethylphenol); 2,2'-methylenebis (4-methyl-6-cyclohexylphenol); 2,6-di-tert-butyl-4 -Methylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,4-dimethyl-6-tert-butylphenol; 2,6-di-tert-butyl-4- (N, N'-dimethyl) Aminomethyl) phenol; 4,4'-thiobis (2-methyl-6-tert-butylphenol); 4,4'-thiobis (3-methyl-6-tert-butylphenol); 2,2'-thiobis (4-) Methyl-6-tert-butylphenol); bis (3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide; bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide; 2,2 '-Thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]; tridecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; Pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]; octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; octadecyl- 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; 3-methyl-5-tert-butyl-4-hydroxyphenol fatty acid esters and the like can be mentioned.

When the gear oil composition contains the component (I), the content thereof is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 1.5% by mass based on the total amount of the composition. , 0.1 to 1.0% by weight in one embodiment.

<Other additives>
In one embodiment, the gear oil composition comprises an organic molybdenum compound other than the components (F) and (G), a corrosion inhibitor other than the component (F), a rust preventive, and a metal inert other than the component (F). It may further comprise one or more additives selected from agents, anti-emulsifiers, antifoaming agents, and colorants.
1

Examples of the organic molybdenum compound other than the component (F) and the component (G) include molybdenum compounds (for example, molybdenum oxide such as molybdenum dioxide and molybdenum trioxide, orthomolybdenum acid, paramolybdenum acid, and (poly) molybdenum sulfide acid. Molybdenum acid, metal salts of these molybdenum acids, molybdates such as ammonium salts, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, molybdenum sulfide such as polymolybdenum sulfide, molybdenum sulfide, metal salts of molybdenum sulfide Amine salts, molybdenum halides such as molybdenum chloride, etc.) and sulfur-containing organic compounds (eg, alkyl (thio) xanthate, thiadiazol, mercaptothiaizole, thiocarbonate, tetrahydrocarbyltiuram disulfide, bis (di (thio) hydro). Calvirdithiophosphonate) disulfide, organic (poly) sulfate, sulfide ester, etc.) or complexes with other organic compounds; and the above-mentioned sulfur-containing molybdenum compounds such as molybdenum sulfide and molybdenum sulfide and alkenyl succinate imide. Examples thereof include organic molybdenum compounds containing sulfur such as complexes. The organic molybdenum compound may be a mononuclear molybdenum compound or a polynuclear molybdenum compound such as a dinuclear molybdenum compound or a trinuclear molybdenum compound.

Further, as a molybdenum-based friction modifier other than the components (F) and (G), an organic molybdenum compound containing no sulfur as a constituent element can also be used. Specific examples of the sulfur-free organic molybdenum compound as a constituent element include molybdenum-amine complex, molybdenum-succinateimide complex, molybdenum salt of organic acid, molybdenum salt of alcohol, and the like. Among them, molybdenum-amine. Complexes, molybdenum salts of organic acids and molybdenum salts of alcohols are preferred.

The gear oil composition may or may not contain an organic molybdenum compound, but the total content of the organic molybdenum compounds in the gear oil composition is preferably 100 as the molybdenum amount based on the total amount of the composition. It may be less than mass ppm, more preferably less than 70 mass ppm, and in one embodiment less than 50 mass ppm. When the content of the organic molybdenum compound is less than the above upper limit value, it is possible to improve the shift feeling when the gear oil composition is used as the manual transmission oil.

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

As the rust preventive, for example, known rust preventives such as petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester can be used without particular limitation. When the gear oil composition contains these rust preventives, the content thereof is usually 0.1% by weight or more and 2.0% by weight or less based on the total amount of the composition.

Examples of the metal inactivating agent other than the component (F) include imidazoline, a pyrimidine derivative, mercaptobenzothiazole, benzotriazole and its derivative, 2- (alkyldithio) benzoimidazole, and β- (o-carboxybenzylthio). A known metal inactivating agent such as propionnitrile can be used. When the gear oil composition contains these metal inactivating agents, the content thereof is usually 0.05% by weight or more and 1.0% by weight or less based on the total amount of the composition.

As the anti-emulsifier, for example, known anti-emulsifiers such as polyalkylene glycol-based nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether are used without particular limitation. It is possible. When the gear oil composition contains these anti-emulsifiers, the content thereof is usually 0.1% by weight or more and 1.0% by weight or less based on the total amount of the composition.

As the defoaming agent, for example, known defoaming agents such as silicone, fluorosilicone, and fluoroalkyl ether can be used. When the gear oil composition contains these antifoaming agents, the content thereof is usually 0.001% by mass or more and 0.01% by mass or less based on the total amount of the composition.

As the colorant, a known colorant such as an azo compound can be used without particular limitation.

The poly (meth) acrylate compound is an additive known in the field of lubricating oil as a viscosity index improver and / or a pour point lowering agent. The gear oil composition may or may not contain a poly (meth) acrylate compound. However, the total content of the poly (meth) acrylate compound in the gear oil composition is preferably less than 1% by mass, more preferably less than 0.8% by mass, based on the total amount of the composition. It can be less than 0.6% by weight in form. When the content of the poly (meth) acrylate compound is less than the above upper limit value, the shear stability can be further improved.

<Characteristics of gear oil composition>
Kinematic viscosity at 40 ° C. of the gear oil composition, preferably 20 to 80 mm ² / s, more preferably from 30 to 60 mm ² / s, it may be 34~58mm ² / s in one embodiment. When the kinematic viscosity of the gear oil composition at 40 ° C. is not more than the above upper limit value, it is possible to improve fuel efficiency. Further, when the kinematic viscosity of the gear oil composition at 40 ° C. is at least the above lower limit value, the seizure resistance and the fatigue life can be further improved.

The kinematic viscosity of the gear oil composition at 100 ° C. is preferably 4.0 to 15.0 mm ² / s, more preferably 6.0 to 13.0 mm ² / s, and 6.9 to 13.0 mm in one embodiment. It can be 11.2 mm ^{2 / s.} When the kinematic viscosity of the gear oil composition at 100 ° C. is not more than the above upper limit value, it is possible to improve fuel efficiency. Further, when the kinematic viscosity of the gear oil composition at 100 ° C. is at least the above lower limit value, the seizure resistance and the fatigue life can be further improved.

The viscosity index of the gear oil composition is preferably 150 or more, more preferably 160 or more. The upper limit of the viscosity index of the gear oil composition is not particularly limited, but is usually 300 or less, and may be 200 or less in one embodiment. When the viscosity index of the gear oil composition is at least the above lower limit value, it is possible to improve fuel efficiency.

(Use)
Since the gear oil composition of the present invention has improved shear stability, extreme pressure resistance, and fatigue resistance in a well-balanced manner, it can be preferably used as a manual transmission oil (for example, a manual transmission oil for automobiles). It can also be preferably used as a lubricating oil for differential gears (for example, final stage transmission oil for automobiles). Further, for example, it can be preferably used as a common lubricating oil for a manual transmission for an automobile and a differential gear, that is, a combined oil for the manual transmission oil and the final stage transmission oil. Using the gear oil composition as such a common lubricating oil includes supplying the gear oil composition to a manual transmission and supplying the gear oil composition to a differential gear.

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

<Examples 1 to 19 and Comparative Examples 1 to 5>
As shown in Tables 1 to 4, the gear oil composition of the present invention (Examples 1 to 19) and the gear oil composition for comparison (Comparative Examples 1 to 5) were prepared, respectively. In the table, in the item of "base oil composition", "mass%" means mass% based on the total amount of base oil, and in other items, "mass%" means mass% based on the total amount of composition. The details of the ingredients are as follows.

((A) Lubricating oil base oil)
A1-1: Ester base oil (ester of trimethylolpropane and oleic acid, hydroxyl value: 16.6 mgKOH / g, acid value: 0.51 mgKOH / g, kinematic viscosity (40 ° C.): 49.1 mm ² / s, Dynamic viscosity (100 ° C.): 9.7 mm ² / s, viscosity index: 187)
A1-2: Ester base oil (ester of trimethylolpropane and oleic acid, hydroxyl value: 9.46 mgKOH / g, acid value: 1.01 mgKOH / g, kinematic viscosity (40 ° C.): 48.7 mm ² / s, Dynamic viscosity (100 ° C.): 9.8 mm ² / s, viscosity index: 192)
A1-3: Ester base oil (bis (2-ethylhexyl azereate), hydroxyl value: 3.22 mgKOH / g, acid value: 0.02 mgKOH / g, kinematic viscosity (40 ° C.): 11.0 mm ² / s, dynamic Viscosity (100 ° C.): 3.1 mm ² / s, viscosity index: 146)
A2-4: Wax isomerized base oil (Group III, kinematic viscosity (40 ° C): 15.7 mm ² / s, kinematic viscosity (100 ° C): 3.8 mm ² / s, viscosity index: 143, sulfur content: 1 (Mass less than ppm)
A2-5: Poly-α-olefin (Group IV, kinematic viscosity (40 ° C): 5.0 mm ² / s, kinematic viscosity (100 ° C): 1.7 mm ² / s)
A2-6: Polyα-olefin (Group IV, kinematic viscosity (40 ° C.): 18.4 mm ² / s, kinematic viscosity (100 ° C.): 4.1 mm ² / s, viscosity index: 124)
A2-7: Poly-α-olefin (Group IV, kinematic viscosity (40 ° C.): 66.0 mm ² / s, kinematic viscosity (100 ° C.): 10.0 mm ² / s, viscosity index: 137)
A2-8: Poly-α-olefin (Group IV, kinematic viscosity (40 ° C.): 412 mm ² / s, kinematic viscosity (100 ° C.): 50 mm ² / s, viscosity index: 186)

((B) Polymer)
B-1: Ethylene-propylene copolymer, number average molecular weight: 7200, kinematic viscosity (100 ° C.): 2000 mm ² / s, viscosity index: 300
B-2: Ethylene-propylene copolymer, number average molecular weight: 5100, kinematic viscosity (100 ° C.): 600 mm ² / s, viscosity index: 240
B ^* -3: Non-dispersed polyalkyl methacrylate, weight average molecular weight: 40,000

((C) Dithiophosphate ester compound)
C-1: Dithiophosphate triester compound represented by the general formula (1), R ¹ = R ² = isobutyl group, R ³ = methyl group

((P) Other additives)
P-1: Ca-based cleaning agent as the component (D) is 4.25% by mass (3400% by mass as the amount of Ca) based on the total amount of the composition; 0.51% by mass based on the standard; 0.9% by mass of olefin sulfide (S amount: 46.0% by mass) as the component (F) based on the total amount of the composition, and 1 by mass of zinc dialkyldithiophosphate based on the total amount of the composition. .56% by mass; (G) component dodecylamine salt of phosphite diester was 0.5% by mass based on the total amount of the composition, and phosphoric acid ester was 0.03% by mass based on the total amount of the composition; (H). Amine-based friction modifier as a component is 0.35% by mass based on the total amount of the composition; (I) Amine-based antioxidant as a component is 0.25% by mass based on the total amount of the composition; and polydimethylsilicone as an antifoaming agent. A performance additive package containing 80% by mass based on the total amount of the composition.

(High-speed walk test)
For each of the gear oil compositions, the final non-seizure load (LNSL) was measured at a rotation speed of 1800 rpm by a high-speed walk test in accordance with JPI-5S-40-93. The higher the LNSL value, the higher the extreme pressure resistance (wear resistance) of the gear oil composition. The results are shown in Tables 1-4.

(EHL test)
For each of the gear oil compositions, the oil film thickness in the elastic fluid lubrication state was measured by the optical interferometry using an EHL tester (EHD2 oil film thickness measuring instrument manufactured by PCS). The measurement conditions are as follows.
Steel ball: PCS Standard Ball (material: SUJ-2), diameter 19.05 mm
Disc: A glass disc having a glass substrate, a chromium layer coated on the surface of the glass substrate, and a silica layer coated on the surface of the chromium layer. Oil temperature: 60 ° C.
Load: 20N
Average Hertz pressure: 0.54 GPa
Peripheral speed: 0.001 to 3 m / s
Slip rate: 0%
The results are shown in Tables 1-4. The thicker the oil film thickness measured in this test, the better the oil film retention.

(Unisteel test)
Unisteel test (British Petroleum Society) for each gear oil composition using a Unisteel rolling fatigue tester (triple high temperature rolling fatigue tester (TRF-1000 / 3-01H), manufactured by Tokyo Testing Machine Co., Ltd.) The rolling fatigue life of the thrust bearing was measured by the method: IP305 / 79). For a test bearing in which the raceway ring on one side of the thrust needle bearing (FNTA-2542C manufactured by NSK) is replaced with a flat test piece (material: SUJ2), the conditions are a load of 7000 N, a surface pressure of 2 GPa, a rotation speed of 1410 rpm, and an oil temperature of 120 ° C. Below, the time until either the roller or the test piece was fatigue-damaged was measured. When the vibration acceleration of the test unit measured by the vibration accelerometer provided in the Unisteel rolling fatigue tester ^{reached 1.5 m / s 2} , it was determined that fatigue damage had occurred. From the time to fatigue damage in 10 repeated tests, the fatigue life was calculated as 50% life (L50: time when the cumulative probability becomes 50%) by the Weibull plot. The results are shown in Tables 1-4. The longer the 50% life measured in this test, the better the fatigue resistance.

(MTM test)
A ball-on-disc friction test was performed on each of the gear oil compositions using an MTM traction measuring instrument (manufactured by PCS Instruments), and the traction coefficient was measured. The measurement conditions are as follows.
Balls and discs: Standard test piece (AISI52100 standard)
Oil temperature: 80 ° C
Load: 30N
Peripheral speed: 3000 mm / s to 50 mm / s
Slip rate: 50%
Based on the measured traction coefficient, the ratio μ (1000) / μ (300) of the traction coefficient μ (1000) at a peripheral speed of 1000 mm / s to the traction coefficient μ (300) at a peripheral speed of 300 mm / s was calculated. The results are shown in Tables 1-4. The closer the calculated ratio μ (1000) / μ (300) is to 1, the lower the traction coefficient is to the low slip speed region, and the better the fuel efficiency is.

(ISOT Oxidation Stability Test)
Oxidation stability was evaluated for each of the gear oil compositions by an ISOT test conforming to JIS K2514. The test was carried out at an oil temperature of 150 ° C. for 96 hours, and the increase in acid value (mgKOH / g) after the test was measured. The results are shown in Tables 1-4. The smaller the increase in acid value after the test, the better the oxidative stability.

(Shear stability test)
The shear stability of the gear oil composition was evaluated by a shear stability test based on JPI-5S-29-88 for each of the gear oil compositions. The sample oil is irradiated with ultrasonic waves having a frequency of 10 kHz and a swing width of 28 μm from the vibrator for 1 hour, and the kinematic viscosity of the sample oil after ultrasonic irradiation at 100 ° C. is measured at 100 ° C. of the sample oil before ultrasonic irradiation. The rate of decrease (%) with respect to the kinematic viscosity was calculated. The results are shown in Tables 1-4. The lower the rate of decrease in kinematic viscosity, the higher the shear stability and the better the shear stability.

(Evaluation results)
The gear oil compositions of Examples 1 to 18 gave good results not only in shear stability, extreme pressure resistance (wear prevention property), and fatigue resistance, but also in oil film thickness, oxidation stability, and fuel efficiency. Indicated.
The gear oil compositions of Comparative Examples 1 and 2 containing no component (B) showed not only inferior results in fatigue resistance but also inferior results in oil film thickness and fuel efficiency.
The gear oil composition of Comparative Example 3 containing no component (A) showed inferior results in fatigue resistance.
The gear oil composition of Comparative Example 4 containing no component (C) showed inferior results in extreme pressure resistance (wear resistance).
The gear oil composition of Comparative Example 5 containing polymethacrylate instead of the component (B) as a polymer showed not only inferior results in shear stability but also inferior results in oil film thickness and fuel efficiency. showed that.

Claims (6)

(A) (A1) ester-based base oil is 0.5 to 25% by mass based on the total amount of base oil, and (A2) API base oil classification group II base oil, API base oil classification group III base oil, or API group. Lubricating oil base oils containing oil classification group IV base oils or mixtures thereof, and
(B) An ethylene-α-olefin copolymer having a kinematic viscosity at 100 ° C. of 500 to 3000 mm ² / s was added to 1.0 to 10.0% by mass based on the total amount of the composition.
(C) A gear oil composition containing a dithiophosphate triester compound having a carboxy group in an amount of 0.1 to 1.5% by mass based on the total amount of the composition. The gear oil composition according to claim 1, wherein the component (C) is a compound represented by the following general formula (1).

(In the general formula (1), R ¹ and R ² are independently an alkyl group having 3 to 18 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, a cycloalkylmethyl group having 6 to 7 carbon atoms, and 10 carbon atoms, respectively. ~ 11 bicycloalkylmethyl groups, 10-11 carbon tricycloalkylmethyl groups, phenyl groups, or 7-24 carbons alkylphenyl groups, or interconnected 2,2-dimethylpropane-1,3 -Represents a diyl group, R ³ represents a hydrogen atom or a methyl group.) The kinematic viscosity of the (A) lubricating oil base oil at 100 ° C. is 3.0 to 6.5 mm ² / s.
The kinematic viscosity of the composition at 40 ° C. is 34-58 mm ² / s.
The gear oil composition according to claim 1 or 2. The gear oil composition according to any one of claims 1 to 3, wherein the poly (meth) acrylate compound is contained or not contained in an amount of less than 1% by mass based on the total amount of the composition. The gear oil composition according to any one of claims 1 to 4, wherein the organic molybdenum compound is contained or not contained in an amount of less than 100 mass ppm as the molybdenum amount based on the total amount of the composition. The gear oil composition according to any one of claims 1 to 5, which is used for lubricating a manual transmission for an automobile.