JP2015098592A - Lubricant composition for reduction gear of hybrid car or electric car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition for a reduction gear of a hybrid car or electric car excellent in low temperature fluidity and shear stability and excellent in abrasion resistance and fatigue life capable of making low fuel consumption.SOLUTION: There is provided a lubricant composition for a reduction gear of a hybrid car or electric car contains synthetic base oil, a lubricant base oil having a traction coefficient of 0.007 or less at 25°C and a pour point depressant having a weight average molecular weight of 40000 to 100000, has the content of the pour point depressant of 0.1 to 1.0 mass% based on the total amount of the lubricant composition, and satisfies the following formula (1): 0.01≤[C/(C×C)]≤0.025, where Cexpresses the phosphorus content in the lubricant composition, and C, Cand Care contents (mass) based on the lubricant composition.

Description

  The present invention relates to a lubricating oil composition for a speed reducer of a hybrid vehicle or an electric vehicle.

  In recent years, there has been a strong demand for carbon dioxide reduction from the viewpoint of global environmental protection. Therefore, in the field of automobiles, efforts are being made to develop fuel-saving technologies. Hybrid vehicles and electric vehicles are the mainstream for fuel saving, and are expected to spread rapidly in the future. A hybrid vehicle and an electric vehicle are characterized by having an electric motor, a generator, an inverter, a storage battery, and the like, and a part or all of the vehicle is driven by the electric motor.

  ATF (automatic transmission fluid) and CVTF (continuous variable transmission fluid) are used for cooling the conduction motor and the generator in such hybrid vehicles and electric vehicles. In ATF and CVTF, synthetic oils such as mineral oil and poly α-olefin are generally used as base oils. On the other hand, hybrid vehicles and electric vehicles have a gear reducer and are required to have both low-temperature fluidity and lubricity. In the future, in order to improve fuel economy, electricity consumption, etc. in hybrid vehicles and electric vehicles, lubricating oils with excellent low-temperature fluidity, such as electric motors and generators, are desired, and it is necessary to lower the viscosity of the lubricating oil. .

  As a conventional lubricating oil composition for automatic transmissions, it has been proposed that various additives are added to a lubricating base oil as having a long fatigue life even with low viscosity and excellent balance in durability. (For example, refer to Patent Document 1).

  However, the amount of lubricating oil used for gear reducers of hybrid vehicles or electric vehicles, particularly electric motors or in-wheel motors, and in particular in-wheel motors, is small compared to automatic transmissions and continuously variable transmissions. When subjected to proper shearing, the viscosity decreases, and the lubricating performance including wear resistance may deteriorate.

JP 2007-284564 A

  The present invention has been made in view of such circumstances, and is excellent in low-temperature fluidity and shear stability, and has excellent wear resistance and fatigue life that can reduce fuel consumption. It is an object to provide a lubricating oil composition.

  In order to solve the above problems, the present invention provides a lubricating oil composition shown in the following [1] and [2], use of the composition shown in the following [3], and production of the composition shown in the following [4]. Provide use for.

[1] A lubricating oil composition comprising a lubricating base oil containing a synthetic base oil and having a traction coefficient of 0.007 or less at 25 ° C. and a pour point depressant having a weight average molecular weight of 40,000 to 100,000. A lubricating oil composition for a speed reducer of a hybrid vehicle or an electric vehicle, wherein the content of the pour point depressant is 0.1 to 1.0% by mass based on the total amount of matter and satisfies the following formula (1).
0.01 ≦ [C _S / (C _B × C _P )] ≦ 0.025 (1)
[Wherein C _S represents the sulfur content in the lubricating oil composition, C _B represents the boron content in the lubricating oil composition, C _P represents the phosphorus content in the lubricating oil composition, and C _S, is a content at C _B and C _P are both lubricating oil composition the total amount (mass). ]
[2] An additive containing phosphorus and sulfur, and an additive containing boron, and the additive containing phosphorus and sulfur includes phosphorus as a constituent element and no sulfur. Combination with a second additive containing sulfur as a constituent element and not containing phosphorus, a third additive containing both phosphorus and sulfur as constituent elements, the first additive and the third additive Selected from the group consisting of a combination, a combination of the second additive and the third additive, and a combination of the first additive, the second additive and the third additive. The lubricating oil composition for a speed reducer of a hybrid vehicle or an electric vehicle according to [1], which is one type.

[3] Use of the composition as a lubricant for a reduction gear of a hybrid vehicle or an electric vehicle, wherein the composition includes a synthetic base oil and a traction coefficient at 25 ° C. is 0.007 or less. An oil base oil and a pour point depressant having a weight average molecular weight of 40,000 to 100,000, and based on the total amount of the lubricating oil composition, the content of the pour point depressant is 0.1 to 1.0% by mass. Yes, satisfying the following formula (1).
0.01 ≦ [C _S / (C _B × C _P )] ≦ 0.025 (1)
[Wherein C _S represents the sulfur content in the lubricating oil composition, C _B represents the boron content in the lubricating oil composition, C _P represents the phosphorus content in the lubricating oil composition, and C _S, is a content at C _B and C _P are both lubricating oil composition the total amount (mass). ]
[4] Use of the composition for producing a lubricant for a reduction gear of a hybrid vehicle or an electric vehicle, wherein the composition contains a synthetic base oil and a traction coefficient at 25 ° C. is 0.007 or less. And a pour point depressant having a weight average molecular weight of 40,000 to 100,000, and based on the total amount of the lubricating oil composition, the content of the pour point depressant is 0.1 to 1.0. Use which is mass% and satisfies the following formula (1).
0.01 ≦ [C _S / (C _B × C _P )] ≦ 0.025 (1)
[Wherein C _S represents the sulfur content in the lubricating oil composition, C _B represents the boron content in the lubricating oil composition, C _P represents the phosphorus content in the lubricating oil composition, and C _S, is a content at C _B and C _P are both lubricating oil composition the total amount (mass). ]

  ADVANTAGE OF THE INVENTION According to this invention, the lubricating oil composition which was excellent in the low temperature fluidity | liquidity and shear stability, and was excellent in the abrasion resistance and fatigue life which can be made fuel-saving is provided. Therefore, when applied to a hybrid vehicle or electric vehicle reducer, in particular, an electric motor or an in-wheel motor, it is possible to achieve fuel saving while maintaining necessary characteristics as a reducer oil. Among them, it is suitable for an electric vehicle having no auxiliary power source.

  Hereinafter, preferred embodiments of the present invention will be described.

The lubricating oil composition for a speed reducer of a hybrid vehicle or an electric vehicle according to the present embodiment includes (A) a lubricating base oil containing a synthetic base oil and having a traction coefficient at 25 ° C. of 0.007 or less; B) a pour point depressant having a weight average molecular weight of 40,000 to 100,000, and based on the total amount of the lubricating oil composition, the content of the pour point depressant is 0.1 to 1.0% by mass. Satisfy (1).
0.01 ≦ [C _S / (C _B × C _P )] ≦ 0.025 (1)
[Wherein C _S represents the sulfur content in the lubricating oil composition, C _B represents the boron content in the lubricating oil composition, C _P represents the phosphorus content in the lubricating oil composition, and C _S, is a content at C _B and C _P are both lubricating oil composition the total amount (mass). ]

[(A) component: lubricating base oil]
The lubricating oil composition according to the present embodiment contains (A) a synthetic base oil and a lubricating base oil having a traction coefficient at 25 ° C. of 0.007 or less.

  Synthetic base oils include poly α-olefins or their hydrides, isobutene oligomers or their hydrides, isoparaffins, alkylbenzenes, alkylnaphthalenes, monobasic acid esters, dibasic acid esters, and other ester base oils, polyoxyalkylene glycols , Dialkyl diphenyl ethers, polyphenyl ethers, base oils produced by catalytic dewaxing of waxes produced from the Fischer-Tropsch process, and the like. These base oils may be used alone or in combination of two or more at any ratio.

  The content of the synthetic base oil is not particularly limited, but is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more, based on the total amount of the lubricating base oil. . Further, the content of the synthetic base oil may be 100% by mass based on the total amount of the lubricating base oil. By setting the content to 30% by mass or more, it becomes possible to obtain a lubricating oil composition having excellent low-temperature fluidity and fatigue life.

  The synthetic base oil preferably contains a poly α-olefin. Specific examples of the poly-α-olefin include oligomers or co-oligomers having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms (for example, 1-octene oligomer, 1-decene oligomer, 1-dodecene oligomer). , Ethylene-propylene co-oligomer and the like) and hydrides thereof.

  Although there is no restriction | limiting in particular about the manufacturing method of poly alpha olefin, For example, aluminum trichloride, boron trifluoride, or boron trifluoride and water, alcohol (for example, ethanol, propanol, or butanol), carboxylic acid, or ester ( For example, polymerization of α-olefin in the presence of a polymerization catalyst such as a Friedel-Crafts catalyst containing a complex with ethyl acetate or ethyl propionate) may be mentioned.

  The content in the case of containing the poly α-olefin is preferably 60% by mass or more, more preferably 65% by mass or more, and further preferably 70% by mass or more, based on the total amount of the lubricating base oil. Further, the content of the poly α-olefin may be 100% by mass based on the total amount of the lubricating base oil. By setting the content to 60% by mass or more, it becomes possible to obtain a lubricating oil composition that is superior in low-temperature fluidity and fatigue life.

The kinematic viscosity at 40 ° C. of the poly α-olefin is not particularly limited, but is preferably 5 mm ² / s or more, more preferably 10 mm ² / s or more, and further preferably 15 mm ² / s or more. Moreover, Preferably it is 50 mm < ² > / s or less, More preferably, it is 40 mm < ² > / s or less, More preferably, it is 35 mm < ² > / s or less. When the kinematic viscosity at 40 ° C. is 5 mm ² / s or more, or 50 mm ² / s or less, extreme pressure properties, wear resistance, and seizure resistance tend to be excellent.

  The viscosity index of the poly α-olefin is not particularly limited, but is preferably 100 or more, more preferably 110 or more, and further preferably 120 or more. When the viscosity index is 100 or more, the low temperature fluidity tends to be excellent.

The synthetic base oil preferably contains an ester base oil in addition to the poly α-olefin.

  The alcohol constituting the ester base oil may be a monohydric alcohol or a polyhydric alcohol (polyol), and the acid constituting the ester base oil may be a monobasic acid or a polybasic acid. Moreover, if it is a base oil containing an ester bond, a complex ester compound may be used.

  As the monohydric alcohol, those having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms are usually used. Such alcohols may be linear or branched, It may be saturated or unsaturated. Specific examples of the alcohol having 1 to 24 carbon atoms include methanol, ethanol, linear or branched propanol, linear or branched butanol, and linear or branched pentanol. , Linear or branched hexanol, linear or branched heptanol, linear or branched octanol, linear or branched nonanol, linear or branched decanol , Linear or branched undecanol, linear or branched dodecanol, linear or branched tridecanol, linear or branched tetradecanol, linear or branched Pentadecanol, linear or branched hexadecanol, linear or branched heptadecanol, linear or branched octadecanol, linear or branched nonadecanol , Linear or branched icosa Lumpur, linear or branched Hen'ikosanoru, linear or branched Torikosanoru, such as straight-chain or branched tetracosanol, and mixtures thereof.

  As the polyhydric alcohol (polyol), those having 2 to 10 valences, preferably 2 to 6 valences are usually used. Specific examples of the divalent to 10-valent polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, polyethylene glycol (3 to 15 mer of ethylene glycol), propylene glycol, dipropylene glycol, and polypropylene glycol (3 to 3 of propylene glycol). 15-mer), 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1, Dihydric alcohols such as 3-propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentylglycol; glycerin, polyglycerin (glycerin 2 ~ Octamer, eg diglycerin, trig Serine, tetraglycerin, etc.), trimethylol alkanes (trimethylol ethane, trimethylol propane, trimethylol butane, etc.) and their 2- to 8-mer, pentaerythritol and their 2- to 4-mer, 1,2,4- Butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol, etc. Polysaccharides such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, and the like, and mixtures thereof. It is.

  As the monobasic acid, a fatty acid having 2 to 24 carbon atoms is usually used, and the fatty acid may be linear or branched, and may be saturated or unsaturated. Specifically, for example, acetic acid, propionic acid, linear or branched butanoic acid, linear or branched pentanoic acid, linear or branched hexanoic acid, linear or branched Branched heptanoic acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched decanoic acid, linear or branched undecanoic acid, Linear or branched dodecanoic acid, linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched Hexadecanoic acid, linear or branched heptadecanoic acid, linear or branched octadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, direct Linear or branched heicosanoic acid, linear or branched docosanoic acid, linear or branched tricosanoic acid, Saturated fatty acids such as linear or branched tetracosanoic acid, acrylic acid, linear or branched butenoic acid, linear or branched pentenoic acid, linear or branched hexenoic acid, Linear or branched heptenoic acid, linear or branched octenoic acid, linear or branched nonenic acid, linear or branched decenoic acid, linear or branched Undecenoic acid, linear or branched dodecenoic acid, linear or branched tridecenoic acid, linear or branched tetradecenoic acid, linear or branched pentadecenoic acid, straight Linear or branched hexadecenoic acid, linear or branched heptadecenoic acid, linear or branched octadecenoic acid, linear or branched nonadecenoic acid, linear or branched Icosenoic acid, linear or branched henicosenoic acid, linear or branched docosenoic acid, linear or branched Jo of tricosenoic acid, unsaturated fatty acids such as straight-chain or branched tetracosenoic acid, and mixtures thereof.

  Examples of the polybasic acid include dibasic acids having 2 to 16 carbon atoms and trimellitic acid. The dibasic acid having 2 to 16 carbon atoms may be linear or branched, and may be saturated or unsaturated. Specifically, for example, ethanedioic acid, propanedioic acid, linear or branched butanedioic acid, linear or branched pentanedioic acid, linear or branched hexanedioic acid, Linear or branched heptanedioic acid, linear or branched octanedioic acid, linear or branched nonanedioic acid, linear or branched decanedioic acid, linear Linear or branched undecanedioic acid, linear or branched dodecanedioic acid, linear or branched tridecanedioic acid, linear or branched tetradecanedioic acid, linear or Branched heptadecanedioic acid, linear or branched hexadecanedioic acid, linear or branched hexenedioic acid, linear or branched heptenedioic acid, linear or branched Octene diacid, linear or branched nonene diacid, linear or branched decenedioic acid, linear or branched undecenedioic acid, linear Is branched dodecenedioic acid, linear or branched tridecenedioic acid, linear or branched tetradecenedioic acid, linear or branched heptacenedioic acid, linear or branched Examples thereof include branched hexadecenedioic acid and a mixture thereof.

The combination of the alcohol and the acid forming the ester is arbitrary and is not particularly limited. Examples of the ester that can be used in this embodiment include the following esters, and these esters may be used alone, Two or more kinds may be combined.
(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) polyhydric alcohol and polybasic acid (E) Mixed ester of monohydric alcohol, mixture of polyhydric alcohol and polybasic acid (f) Mixed ester of polyhydric alcohol with monobasic acid, polybasic acid (g) Monohydric alcohol , Mixtures of polyhydric alcohols with monobasic acids and polybasic acids

  Among these, since it is excellent in friction resistance and oxidation stability, it is preferable that it is (a) monobasic acid ester which is ester of monohydric alcohol and monobasic acid.

  When the ester base oil is contained, the content is preferably 1% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more, based on the total amount of the lubricating base oil. Moreover, it is preferably 40% by mass or less, more preferably 35% by mass or less, and further preferably 30% by mass or less. When the content of the ester base oil is 1% by mass or more or 40% by mass or less, the low temperature fluidity tends to be more excellent.

The kinematic viscosity at 40 ° C. of the ester base oil is not particularly limited, but is preferably 5 mm ² / s or more, more preferably 6 mm ² / s or more, and further preferably 7 mm ² / s or more. Moreover, Preferably it is 50 mm < ² > / s or less, More preferably, it is 30 mm < ² > / s or less, More preferably, it is 20 mm < ² > / s or less. When the kinematic viscosity at 40 ° C. is 5 mm ² / s or more, or 50 mm ² / s or less, extreme pressure properties, wear resistance, and seizure resistance tend to be excellent.

  The viscosity index of the ester base oil is not particularly limited, but is preferably 125 or more, more preferably 130 or more, and still more preferably 135 or more. When the viscosity index is 125 or more, the low temperature fluidity tends to be excellent.

  The pour point of the ester base oil is not particularly limited, but is preferably −20 ° C. or lower, more preferably −30 ° C. or lower, and further preferably −40 ° C. or lower.

  The flash point of the ester base oil is not particularly limited, but is preferably 200 ° C. or higher, more preferably 210 ° C. or higher, and further preferably 220 ° C. or higher.

  The lubricating base oil according to this embodiment can contain a base oil component other than the synthetic base oil. Base oil components other than the synthetic base oil are not particularly limited, and base oils used for ordinary lubricating oils can be used. Specifically, a mineral oil base oil or a mixture obtained by mixing two or more base oils selected from these at an arbitrary ratio can be used.

  As mineral base oils, lubricating oil fractions obtained by subjecting crude oil to atmospheric distillation and reduced pressure distillation are subjected to solvent deburring, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid Mineral oil base oils such as paraffinic and naphthenic oils refined by combining purification treatments such as washing and clay treatment alone or in combination of two or more, base oils produced by catalytic dewaxing of normal paraffins, isoparaffins, petroleum waxes, etc. Is mentioned. These base oils may be used alone or in combination of two or more at any ratio.

  Mineral oil base oil is a base oil classified into Group II or Group III defined in the Base Stock Categories of API (American Petroleum Institute) from the viewpoint of viscosity reduction and sulfur content Are preferred, and base oils classified in Group III are more preferred.

  The sulfur content of the mineral oil base oil is not particularly limited, but may be 100 ppm by mass, 50 ppm by mass or 10 ppm by mass based on the total amount of the lubricant base oil. The sulfur content of the mineral base oil can be determined by, for example, ICP elemental analysis.

  The traction coefficient at 25 ° C. of the lubricating base oil of component (A) is 0.007 or less, preferably 0.0065 or less, more preferably 0.006 or less, and still more preferably 0.0055. It is as follows. By setting the traction coefficient at 25 ° C. to 0.007 or less, it is possible to obtain a lubricating oil composition having excellent low-temperature fluidity, shear stability, and fatigue life. Here, the traction coefficient at 25 ° C. is a value measured using an EHL tester under conditions of an oil temperature of 25 ° C., a surface pressure of 0.44 GPa, a slip ratio of 3%, and a peripheral speed of 0.5 m / s.

[(B) component: pour point depressant]
The lubricating oil composition according to this embodiment contains a pour point depressant having a weight average molecular weight of 0.1 to 1.0 mass% and 40000 to 100,000 based on the total amount of the lubricating oil composition. By combining such a pour point depressant with the component (A), it is possible to increase low temperature fluidity and prolong fatigue life by reducing traction and improving oil film thickness.

  The pour point depressant is not particularly limited as long as the weight average molecular weight is 40,000 to 100,000, but it is a poly (meth) acrylate pour point depressant because sufficient low temperature fluidity can be obtained. Is preferred.

  The pour point depressant has a weight average molecular weight of 40,000 to 100,000, and an upper limit of preferably 80,000 or less, more preferably 60000 or less, and even more preferably 50000 or less. By setting the weight average molecular weight of the pour point depressant to 40,000 to 100,000, a lubricating oil composition having sufficient low temperature fluidity and fatigue life can be obtained. Here, the weight average molecular weight means that two columns of GHSHR-M (7.8 mm ID × 30 cm) manufactured by Tosoh Corporation are used in series in a 150-C ALC / GPC apparatus manufactured by Waters, and tetrahydrofuran is used as a solvent. It is a weight average molecular weight in terms of standard polystyrene measured using a differential refractometer (RI) detector under conditions of a temperature of 23 ° C., a flow rate of 1 mL / min, a sample concentration of 1 mass%, and a sample injection amount of 75 μL.

  The content of the pour point depressant is 0.1 to 1.0% by mass based on the total amount of the lubricating oil composition, and the lower limit is preferably 0.2% by mass or more. When the content of the pour point depressant is 0.1% by mass or more, the fatigue life tends to be excellent. When the content of the pour point depressant is 1.0% by mass or less, the shear stability tends to be excellent.

  The lubricating oil composition according to this embodiment preferably further contains a viscosity modifier.

  The viscosity modifier is specifically a non-dispersed or dispersed ester group-containing viscosity modifier, such as a non-dispersed or dispersed poly (meth) acrylate viscosity modifier, a non-dispersed or dispersed olefin- (Meth) acrylate copolymer viscosity modifiers, styrene-maleic anhydride copolymer viscosity modifiers and mixtures thereof, copolymers of α-olefins and ester monomers having a polymerizable unsaturated bond, Examples thereof include a dispersed or dispersed ethylene-α-olefin copolymer or a hydride thereof, polyisobutylene or a hydride thereof, a styrene-diene hydrogenated copolymer, and a polyalkylstyrene.

  Among these, the viscosity modifier is preferably a non-dispersed or dispersed poly (meth) acrylate viscosity modifier. In particular, non-dispersed or dispersed polymethacrylate viscosity modifiers are preferred.

The polymethacrylate viscosity modifier according to this embodiment is a polymethacrylate viscosity modifier having a structural unit represented by the following general formula (1).

In the general formula (1), R ¹ represents hydrogen or a methyl group, preferably a methyl group, and R ² represents a linear or branched hydrocarbon group having 18 to 30 carbon atoms, preferably a group having 20 or more carbon atoms. A branched hydrocarbon group is shown.

  Here, as a linear or branched hydrocarbon group having 18 to 30 carbon atoms, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group Group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, etc. (these alkyl groups may be linear or branched); hexadecenyl group, heptadecenyl group, octadecenyl group, nonadecenyl group, icocenyl group Alkenyl groups such as henicosenyl group, dococenyl group, tricocenyl group, tetracocenyl group, pentacocenyl group, hexacocenyl group, heptacocenyl group, octacocenyl group, nonacosenyl group and triaconenyl group (these alkenyl groups may be linear or branched) , The position of the double bond is also arbitrary) and the like.

  The composition ratio of the structural unit represented by the general formula (1) in the polymethacrylate viscosity modifier is preferably 5 mol% or more, more preferably 15 mol% or more, and further preferably 30 mol% or more. It is. Moreover, from a viewpoint of low-temperature fluidity | liquidity, Preferably it is 80 mol% or less, More preferably, it is 60 mol% or less, More preferably, it is 50 mol% or less.

  The weight average molecular weight of the polymethacrylate viscosity modifier is not particularly limited, but is preferably 5000 or more, more preferably 7000 or more, further preferably 10,000 or more, and particularly preferably 15000 or more. Moreover, it is preferably 30000 or less, more preferably 28000 or less, further preferably 26000 or less, and particularly preferably 24000 or less. In addition, the weight average molecular weight mentioned here uses two columns of Tosoh's GMHHR-M (7.8 mm ID × 30 cm) in series on a Waters 150-C ALC / GPC apparatus, and the solvent is tetrahydrofuran, It means a weight average molecular weight in terms of polystyrene measured by a temperature of 23 ° C., a flow rate of 1 mL / min, a sample concentration of 1 mass%, a sample injection amount of 75 μL, and a detector differential refractometer (RI).

  The content of the polymethacrylate viscosity modifier is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0, based on the total amount of the lubricating oil composition. .5% by mass or more. Moreover, it is preferably 10% by mass or less, more preferably 7% by mass or less, and further preferably 5% by mass or less. By setting the content to 10% by mass or less, an effect of improving the fatigue life commensurate with the content can be expected, and the shear stability tends to be more excellent.

  The viscosity modifier may be a copolymer of an α-olefin and an ester monomer having a polymerizable unsaturated bond.

  The ester monomer having a polymerizable unsaturated bond is not particularly limited as long as it is a compound having a polymerizable unsaturated bond and an ester bond, but at least one of the α carbon and β carbon of the carboxy group is ethylenically unsaturated. An α, β-ethylenically unsaturated dicarboxylic acid diester which is a diester of an unsaturated dicarboxylic acid forming a bond (that is, a C═C double bond) is preferable. Here, the α, β-ethylenically unsaturated dicarboxylic acid forms an ethylenically unsaturated bond with respect to both carboxy groups such as maleic acid, fumaric acid, citraconic acid, and mesaconic acid. And an α, β-ethylenically unsaturated bond is not limited to the compound present in the main chain, and only one carboxy group such as glutaconic acid has the α and β carbons ethylenic. It is a concept that includes a compound having an unsaturated bond, and also includes a compound in which an α, β-ethylenically unsaturated bond is found in the side chain, such as itaconic acid.

  The structure of the copolymer of the α-olefin and the ester monomer having a polymerizable unsaturated bond is not particularly limited. Further, the production method is not particularly limited, and those produced by a known method can be used.

  The weight average molecular weight of the copolymer of the α-olefin and the ester monomer having a polymerizable unsaturated bond is not particularly limited, but is preferably 2000 or more, more preferably 4000 or more, and further preferably 6000. That's it. Moreover, Preferably it is 20000 or less, More preferably, it is 15000 or less, More preferably, it is 12000 or less. By setting the weight average molecular weight to 2000 or more or 20000 or less, the low temperature fluidity can be improved. Here, the weight average molecular weight means that two columns of GHSHR-M (7.8 mm ID × 30 cm) manufactured by Tosoh Corporation are used in series in a 150-C ALC / GPC apparatus manufactured by Waters, and tetrahydrofuran is used as a solvent. It means the weight average molecular weight in terms of standard polystyrene measured using a differential refractometer (RI) detector under the conditions of a temperature of 23 ° C., a flow rate of 1 mL / min, a sample concentration of 1 mass%, and a sample injection amount of 75 μL.

  The content in the case of containing a copolymer of an α-olefin and an ester monomer having a polymerizable unsaturated bond is preferably 0.1% by mass or more, more preferably, based on the total amount of the lubricating oil composition. Is 0.5% by mass or more. Further, it is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 5% by mass or less. By setting the content to 1% by mass or more, the wear resistance and fatigue life tend to be more excellent. Moreover, it exists in the tendency which shows sufficient shear stability, abrasion resistance, and fatigue life by making the content into 10 mass% or less.

  The viscosity modifier may be a non-dispersed or dispersed ethylene-α-olefin copolymer or a hydrogenated product thereof, polyisobutylene or a hydrogenated product thereof, a styrene-diene hydrogenated copolymer, or a polyalkylstyrene. Among these, when an ethylene-α-olefin copolymer or a hydride thereof is used, a lubricating oil composition having excellent shear stability can be obtained.

  It is necessary to select the molecular weight of the non-dispersed or dispersed ethylene-α-olefin copolymer or its hydride in consideration of shear stability. Preferably it is 800 or more, More preferably, it is 1000 or more, More preferably, it is 3000 or more, Most preferably, it is 15000 or more. Moreover, it is preferably 150,000 or less, more preferably 40000 or less, further preferably 30000 or less, and particularly preferably 25000 or less.

  When the non-dispersed or dispersed ethylene-α-olefin copolymer or a hydride thereof is contained, the content is preferably 0.1% by mass or more, more preferably 0, based on the total amount of the lubricating oil composition. .5% by mass or more. Further, it is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 5% by mass or less. By setting the content to 1% by mass or more, the wear resistance and fatigue life tend to be more excellent. Moreover, it exists in the tendency which shows sufficient shear stability, abrasion resistance, and fatigue life by making the content into 10 mass% or less.

The lubricating oil composition according to the present embodiment satisfies the following formula (1) with respect to the sulfur content, the boron content, and the phosphorus content.
0.01 ≦ [C _S / (C _B × C _P )] ≦ 0.025 (1)
[Wherein C _S represents the sulfur content in the lubricating oil composition, C _B represents the boron content in the lubricating oil composition, C _P represents the phosphorus content in the lubricating oil composition, and C _S, is a content at C _B and C _P are both lubricating oil composition the total amount (mass). ]

  The sulfur content, boron content and phosphorus content in the lubricating oil composition can be determined by ICP elemental analysis or the like. In addition, each component blended in the lubricating base oil is analyzed in advance by ICP elemental analysis, etc., and the sulfur content, boron content and phosphorus content in the lubricating oil composition are determined from the analysis values and the charged amounts of each component. The amount can also be determined.

The lower limit of [C _S / (C _B × C _P )] is 0.01 or more, preferably 0.011 or more, more preferably 0.012 or more, and further preferably 0.013 or more. is there. On the other hand, the upper limit of [C _S / (C _B × C _P )] is 0.025 or less, preferably 0.024 or less, more preferably 0.022 or less, and further preferably 0.02 or less. is there. When the lower limit is 0.01 or more, or the upper limit is 0.025 or less, the wear resistance tends to be excellent.

  The lubricating oil composition according to the present embodiment may further contain an additive containing phosphorus and sulfur and an additive containing boron. The additive containing phosphorus and sulfur is a combination of a first additive containing phosphorus as a constituent element and not containing sulfur and a second additive containing sulfur as a constituent element and no phosphorus, as a constituent element. A third additive comprising both phosphorus and sulfur, a combination of the first additive and the third additive, a combination of the second additive and the third additive, and the It may be one selected from the group consisting of a combination of the first additive, the second additive, and the third additive.

  The first additive is an additive that contains phosphorus as a constituent element and does not contain sulfur. Examples of the first additive include phosphorous extreme pressure agents such as phosphites (phosphites), phosphate esters, amine salts thereof, metal salts thereof, derivatives thereof and the like.

  The second additive is an additive that contains sulfur as a constituent element and does not contain phosphorus. Examples of the second additive include dithiocarbamate, zinc dithiocarbamate, molybdenum dithiocarbamate, disulfides, polysulfides, sulfurized olefins, sulfurized fats and oils, and thiadiazoles, and sulfonate-based additives. Metal detergents such as detergents (normal salts with alkali metals or alkaline earth metals, basic salt, overbased salts), corrosion inhibitors such as thiadiazoles, alkyl thiadiazoles, mercaptobenzothiazoles, 1, 3, Metal deactivators such as 4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, β- (o-carboxybenzylthio) propiononitrile, Petroleum sulfonate, alkylbenzene sulfonate DOO, like rust agents such as dinonyl naphthalene sulfonate.

  The third additive is an additive containing both phosphorus and sulfur as constituent elements. Third additives are zinc dialkyldithiophosphate (ZnDTP), thiophosphites, dithiophosphites, trithiophosphites, thiophosphates, dithiophosphates, trithiophosphates And sulfur-phosphorus extreme pressure agents such as amine salts, metal salts thereof, and derivatives thereof.

  Examples of the additive containing boron include ashless dispersants such as boric acid-modified succinimide (boron-containing succinimide).

  The lubricating oil composition according to this embodiment may contain any additive generally used in lubricating oils depending on the purpose. Examples of such additives include metal detergents, ashless dispersants, antioxidants, corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, antifoaming agents, and ashless friction modifiers. And the like.

  Examples of metal detergents include salicylate detergents, phenate detergents, and the like, and any of normal salts, basic normal salts, and overbased salts with alkali metals or alkaline earth metals can be blended. . In use, one kind or two or more kinds arbitrarily selected from these can be blended.

  As the ashless dispersant, any ashless dispersant used in lubricating oils can be used. For example, a mono- or mono-chain having at least one linear or branched alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule. Bisuccinimide, benzylamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, polyamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, and these carboxylic acids Examples of such modified products include acids and phosphoric acid. In use, one kind or two or more kinds arbitrarily selected from these can be blended.

  Examples of the antioxidant include ashless antioxidants such as phenols and amines, and metal antioxidants such as copper and molybdenum. Specifically, for example, as a phenol-based ashless antioxidant, 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert- Butylphenol) and the like are amine-based ashless antioxidants such as phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, and dialkyldiphenylamine.

  Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, and imidazole compounds.

  Examples of the rust preventive include alkenyl succinic acid ester and polyhydric alcohol ester.

  Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.

  Examples of the metal deactivator include imidazoline, pyrimidine derivatives, benzotriazole or derivatives thereof.

Examples of antifoaming agents include silicone oils having a kinematic viscosity at 25 ° C. of 1000 to 100,000 mm ² / s, alkenyl succinic acid derivatives, esters of polyhydroxy aliphatic alcohols and long chain fatty acids, methyl salicylates and o -Esters with hydroxybenzyl alcohol and the like.

  As the ashless friction modifier, any compound usually used as an ashless friction modifier for lubricating oil can be used. For example, an alkyl group or an alkenyl group having 6 to 30 carbon atoms, particularly 6 to 30 carbon atoms. Ash-free friction modifiers such as amine-based, fatty acid ester-based, fatty acid amide-based, fatty acid-based, aliphatic alcohol-based, aliphatic ether-based, etc. having at least one linear alkyl group or linear alkenyl group in the molecule Is mentioned.

The kinematic viscosity at 100 ° C. of the lubricating oil composition according to the present embodiment is not particularly limited, but is preferably 3.5 mm ² / s or more, more preferably 3.7 mm ² / s or more, and further 3. 9 mm ² / s or more. Moreover, it is 7.0 mm < ² > / s or less preferably, More preferably, it is 6.5 mm < ² > / s or less, More preferably, it is 6.0 mm < ² > / s or less. By setting the 100 ° C. kinematic viscosity to 3.5 mm ² / s or more, the formation of an oil film is sufficient, and the lubricity tends to be excellent. Moreover, it exists in the tendency which is excellent in low-temperature fluidity | liquidity by making 100 degreeC kinematic viscosity 7.0 mm < ² > / s or less.

  The BF viscosity at −40 ° C. of the lubricating oil composition according to this embodiment is not particularly limited, but is preferably 10000 mPa · s or less, more preferably 8000 mPa · s or less, and even more preferably 7000 mPa · s or less. is there. Sufficient low-temperature fluidity can be obtained by setting the BF viscosity to 10,000 mPa · s or less.

  The lubricating oil composition according to the present embodiment is excellent in low-temperature fluidity and shear stability, and is excellent in wear resistance and fatigue life that can save fuel, and is therefore suitably used for a hybrid vehicle or electric vehicle reducer. be able to. Among them, it is suitable for an electric vehicle having no auxiliary power source. More preferably for an electric motor or an in-wheel motor, and still more preferably for an in-wheel motor.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, one embodiment of the present invention includes (A) a synthetic base oil, a lubricating base oil having a traction coefficient at 25 ° C. of 0.007 or less, and (B) a weight average molecular weight of 40,000 to 100,000. A pour point depressant, and based on the total amount of the lubricating oil composition, the content of the pour point depressant is 0.1 to 1.0% by mass, and satisfies the above formula (1), The present invention relates to use as a lubricant for a reduction gear of a hybrid vehicle or an electric vehicle. Further, for example, another embodiment of the present invention includes the (A) synthetic base oil and a lubricating base oil having a traction coefficient of 0.007 or less at 25 ° C. and the (B) weight average molecular weight. Of pour point depressant of 40000-100,000, and based on the total amount of the lubricating oil composition, the content of the pour point depressant is 0.1 to 1.0% by mass and satisfies the above formula (1). The present invention relates to the use of the composition for the production of a reduction gear lubricant for hybrid vehicles or electric vehicles.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to an Example.

(Examples 1-18 and Comparative Examples 1-11)
As shown in Table 1 and Table 2, the lubricating oil compositions of Examples 1 to 18 and Comparative Examples 1 to 11 were prepared, respectively. About the obtained lubricating oil composition, low-temperature fluidity | liquidity, shear stability, abrasion resistance, and fatigue life were measured, and the result was written together in Table 1 and Table 2.

Details of each component shown in Table 1 and Table 2 are as follows.
Base oil A-1: Poly α-olefin [Group IV, kinematic viscosity at 40 ° C .: 16.95 mm ² / s, kinematic viscosity at 100 ° C .: 3.862 mm ² / s, viscosity index: 122, traction coefficient at 25 ° C .: 0.00434]
Base oil A-2: Poly α-olefin [Group IV, kinematic viscosity at 40 ° C .: 30.59 mm ² / s, kinematic viscosity at 100 ° C .: 6.012 mm ² / s, viscosity index: 147, traction coefficient at 25 ° C .: 0.00662]
Base oil A-3: Wax isomerized base oil [Group III ⁺ , 40 ° C. kinematic viscosity: 16.86 mm ² / s, 100 ° C. kinematic viscosity: 4.028 mm ² / s, viscosity index: 142, traction at 25 ° C. Coefficient: 0.00395]
Base oil A-4: hydrorefined mineral oil [Group III, kinematic viscosity at 40 ° C .: 8.667 mm ² / s, kinematic viscosity at 100 ° C .: 2.395 mm ² / s, viscosity index: 91, traction coefficient at 25 ° C .: 0.0128]
Base oil A-5: hydrorefined mineral oil [Group III, kinematic viscosity at 40 ° C .: 18.68 mm ² / s, kinematic viscosity at 100 ° C .: 4.160 mm ² / s, viscosity index: 127, traction coefficient at 25 ° C .: 0.0088]
Base oil A-6: Solvent refined base oil [Group I, 40 ° C. kinematic viscosity: 243.1 mm ² / s, 100 ° C. kinematic viscosity: 20.46 mm ² / s, viscosity index: 98, traction coefficient at 25 ° C .: 0.0238]
Base oil A-7: Dibasic acid ester [Group V, azelaic acid + 2 ethylhexanol, 40 ° C. kinematic viscosity: 10.3 mm ² / s, 100 ° C. kinematic viscosity: 2.9 mm ² / s, viscosity index: 138, 25 Traction coefficient at ° C: 0.00303, pour point: -72 ° C, flash point: 220 ° C]
Base oil A-8: monobasic acid ester [Group V, oleic acid + 2 ethylhexanol, 40 ° C. kinematic viscosity: 8.4 mm ² / s, 100 ° C. kinematic viscosity: 2.7 mm ² / s, viscosity index: 174, 25 Traction coefficient at ° C: 0.00192, pour point: -40 ° C, flash point: 224 ° C]
Pour point depressant B-1: Polymethacrylate pour point depressant [weight average molecular weight: 46000]
Pour point depressant B-2: Polymethacrylate pour point depressant [weight average molecular weight: 170000]
Viscosity modifier C-1: polymethacrylate viscosity modifier [weight average molecular weight: 20000, R ² is a hydrocarbon group having 20 to 24 carbon atoms, the structural ratio of the structural unit represented by the general formula (1): 40 Mol%]
Viscosity modifier C-2: Copolymer of α-olefin and carboxylic acid [weight average molecular weight: 12000]
Viscosity modifier C-3: Copolymer of ethylene and α-olefin [number average molecular weight: 13000]
Antiwear agent D-1: Phosphite [phosphorus element conversion: 13.2% by mass]
Extreme pressure agent E-1: thiadiazole [in terms of elemental sulfur: 36% by mass]
Dispersant F-1: Boric acid-modified succinimide [weight average molecular weight: 1000, boron element equivalent: 1.5% by mass]
ATF package G-1: package additives such as succinimide, boron-containing succinimide, sulfur-containing phosphite, calcium sulfonate, metal deactivator, friction modifier, antifoaming agent, and diluent oil [ Based on the total amount of the package additive, sulfur element conversion: 0.44 mass%, boron element conversion: 0.12 mass%, phosphorus element conversion: 0.24 mass%]

  The sulfur content, boron content and phosphorus content in the lubricating oil composition were determined by ICP elemental analysis. In addition, the phosphorus element equivalent amount of the antiwear agent, the sulfur element equivalent amount of the extreme pressure agent, the boron element equivalent amount of the dispersant, the sulfur element equivalent amount of the ATF package, the boron element equivalent amount and the phosphorus element equivalent amount are also measured. Obtained by elemental analysis.

(1) Low temperature fluidity Based on ASTM D 2983, the BF viscosity at −40 ° C. of each lubricating oil composition was measured. In this test, the smaller the value of the BF viscosity, the better the low temperature fluidity.
(2) Shear Stability Test In accordance with JPI-5S-29-88, a sonic test was performed at a measurement temperature of 100 ° C. and an irradiation time of 10 hours, and the rate of decrease was measured from the 100 ° C. kinematic viscosity before and after the sonic test. In this test, the smaller the reduction rate, the better the shear stability.
(3) Abrasion resistance test Based on ASTM D 2596, a maximum non-seizure load (LNSL) at 1800 revolutions of each lubricating oil composition was measured using a high-speed four-ball tester. In this test, the larger the maximum non-seizure load, the better the wear resistance.
In addition, a four-ball test (ASTM D4172) was performed under the following conditions, and the wear scar diameter (mm) was measured to evaluate the wear resistance. In this test, the smaller the wear scar diameter, the better the wear resistance.
Load: 392N
Rotation speed: 1800rpm
Temperature: 80 ° C
Test time: 30 minutes (4) Fatigue life test An FZG tester was used to perform the operation under the following conditions to evaluate the fatigue life of the gears until the gears were pitched.
Load stage: 9
Oil temperature: 120 ° C
Rotation speed: 1440rpm

  As is clear from Tables 1 and 2, the lubricating oil compositions of Examples 1 to 18 have low-temperature fluidity (for example, a BF viscosity at −40 ° C. of 10,000 mPa · s or less) and shear stability (for example, 100 The rate of decrease in kinematic viscosity is 2.0% or less), wear resistance (for example, maximum non-seizure load is 618 N or more, wear scar diameter is 0.60 mm or less), and fatigue life (for example, 24 hours or more) is well balanced. I found it excellent.

Claims (4)

A lubricating base oil containing a synthetic base oil and having a traction coefficient at 25 ° C. of 0.007 or less;
A pour point depressant having a weight average molecular weight of 40,000 to 100,000,
For a reduction gear of a hybrid vehicle or an electric vehicle, wherein the content of the pour point depressant is 0.1 to 1.0% by mass based on the total amount of the lubricating oil composition and satisfies the following formula (1) Lubricating oil composition.
0.01 ≦ [C _S / (C _B × C _P )] ≦ 0.025 (1)
[Wherein C _S represents the sulfur content in the lubricating oil composition, C _B represents the boron content in the lubricating oil composition, C _P represents the phosphorus content in the lubricating oil composition, and C _S, is a content at C _B and C _P are both lubricating oil composition the total amount (mass). ] An additive comprising phosphorus and sulfur;
An additive comprising boron;
Further containing
The additive containing phosphorus and sulfur is a combination of a first additive that contains phosphorus as a constituent element and does not contain sulfur, and a second additive that contains sulfur as a constituent element and does not contain phosphorus, phosphorus as a constituent element, and A third additive comprising both sulfur, a combination of the first additive and the third additive, a combination of the second additive and the third additive, and the first The lubricating oil composition for a hybrid vehicle or electric vehicle according to claim 1, wherein the lubricating oil composition is one selected from the group consisting of a combination of the additive, the second additive, and the third additive. . Use of the composition as a lubricant for a reduction gear of a hybrid vehicle or an electric vehicle,
The composition is
A lubricating base oil containing a synthetic base oil and having a traction coefficient at 25 ° C. of 0.007 or less;
A pour point depressant having a weight average molecular weight of 40,000 to 100,000,
The content of the pour point depressant is 0.1 to 1.0% by mass based on the total amount of the lubricating oil composition, and satisfies the following formula (1).
0.01 ≦ [C _S / (C _B × C _P )] ≦ 0.025 (1)
[Wherein C _S represents the sulfur content in the lubricating oil composition, C _B represents the boron content in the lubricating oil composition, C _P represents the phosphorus content in the lubricating oil composition, and C _S, is a content at C _B and C _P are both lubricating oil composition the total amount (mass). ] Use of the composition for the manufacture of a lubricant for a reduction gear of a hybrid vehicle or an electric vehicle,
The composition is
A lubricating base oil containing a synthetic base oil and having a traction coefficient at 25 ° C. of 0.007 or less;
A pour point depressant having a weight average molecular weight of 40,000 to 100,000,
The content of the pour point depressant is 0.1 to 1.0% by mass based on the total amount of the lubricating oil composition, and satisfies the following formula (1).
0.01 ≦ [C _S / (C _B × C _P )] ≦ 0.025 (1)
[Wherein C _S represents the sulfur content in the lubricating oil composition, C _B represents the boron content in the lubricating oil composition, C _P represents the phosphorus content in the lubricating oil composition, and C _S, is a content at C _B and C _P are both lubricating oil composition the total amount (mass). ]