JP5941530B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition, and more particularly, it has excellent fatigue life and extreme pressure properties even at low viscosity, and does not deteriorate extreme pressure performance even after long-term use. The present invention relates to a lubricating oil composition suitable for a reduction gear or the like.

  In recent years, there has been an urgent need to save energy in automobiles, construction machinery, agricultural machinery, etc., that is, to save fuel, in response to environmental issues such as reducing carbon dioxide emissions. Engines, transmissions, final reduction gears, compression Devices such as machines and hydraulic devices are strongly required to contribute to energy saving. Therefore, the lubricating oil used for these is required to reduce the stirring resistance and frictional resistance as compared with the conventional one.

  As one of the fuel saving means of the transmission and the final reduction gear, there is a reduction in viscosity of the lubricating oil. For example, manual transmissions for automobiles and final reduction gears have gear bearing mechanisms. By lowering the viscosity of the lubricating oil used in these gears, stirring resistance and friction resistance are reduced, and power transmission efficiency is improved. By improving, it becomes possible to improve the fuel consumption of the automobile.

  However, when the viscosity of the lubricating oil used in these is reduced, the fatigue life or extreme pressure properties are reduced, and seizure or the like may occur, causing problems in the transmission or the like. In particular, when a phosphorus-based extreme pressure agent is blended in order to improve the extreme pressure property of a low viscosity oil, the fatigue life is remarkably deteriorated, and it is generally difficult to reduce the viscosity. Viscosity index improvers can improve the viscosity characteristics of lubricating oils at low or practical temperatures, but are generally not expected to improve fatigue life and extreme pressure properties. When used, it is known to cause a decrease in viscosity due to shear over a long period of use.

  As conventional transmission oils for automobiles, various performances such as transmission characteristics can be maintained for a long period of time. Synthetic oils and / or mineral oil base oils, antiwear agents, extreme pressure agents, metallic detergents, The thing which optimized and mix | blended the ash dispersing agent, the friction modifier, the viscosity index improver, etc. is disclosed (for example, refer patent documents 1-3).

  However, none of these compositions are intended to improve fuel efficiency, so their kinematic viscosity is high, and the impact on fatigue life when reducing the viscosity of the lubricating oil and extreme pressure properties during initial and long-term use. Has not been studied at all, and thus compositions that can solve such problems have not been sufficiently studied so far.

JP-A-3-39399 JP 7-268375 A JP 2000-63869 A

  The present invention has been made in view of such circumstances, and the object of the present invention is to provide a lubricating oil composition, particularly an automobile, which has a long fatigue life even with a low viscosity and has a sufficient extreme pressure even after initial and long-term use. It is an object of the present invention to provide a lubricating oil composition that is suitable for a manual transmission, a final reduction gear and the like and has both fuel saving performance and sufficient durability such as gears and bearings.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have a specific viscosity index improver and, if necessary, a specific extreme pressure to a base oil composed of a specific mineral base oil and a specific synthetic lubricant. The present inventors have found that a lubricating oil composition containing an additive and a specific metal-based detergent can solve the above problems, and has completed the present invention.

That is, the present invention relates to (A) a mineral base oil having a kinematic viscosity at 100 ° C. of ² to 6 mm ² / s,% CA of 0.5% or less, and tertiary carbon content of 7% or more, and (B) 100. A poly-α-olefin having a kinematic viscosity at 6 ° C. of 6 mm ² / s to 160 mm ² / s and / or its hydride is 2 to 40% by mass based on the total amount of base oil, and (C) the kinematic viscosity at 100 ° C. is 2 (D) Poly ((weight) having a weight average molecular weight of 5,000 or more and 200,000 or less is added to a base oil obtained by blending 5 to 20% by mass of an ester base oil of 10 mm ² / s based on the total amount of the base oil composition. The present invention relates to a lubricating oil composition for a gear unit for automobiles having a kinematic viscosity at 100 ° C. of 10 mm ² / s or less, comprising a ( meth) acrylate viscosity index improver.

  The lubricating oil composition of the present invention can sufficiently reduce friction under mixed lubrication conditions, and the agitation resistance of gears, transmission clutches, torque converters and oil pumps can be reduced, and fuel consumption in transmissions and final reduction gears is reduced. Not only can improvement be expected, but the composition can also be made excellent in bearing fatigue life and extreme pressure properties such as gears. Therefore, the lubricating oil composition of the present invention is extremely effective as an unprecedented fuel-saving transmission lubricating oil composition.

（一般式（１）において、Ｒ^１は水素又はメチル基、Ｒ^２は炭素数１〜３０の炭化水素基を示す。） Hereinafter, the present invention will be described in detail.
(1) The lubricating oil composition of the present invention comprises (A) a mineral oil base having a kinematic viscosity at 100 ° C. of ² to 6 mm ² / s,% CA of 0.5% or less, and tertiary carbon content of 7% or more. ² to 40% by mass of the oil and (B) poly-α-olefin having a kinematic viscosity at 100 ° C. of 6 mm ² / s to 160 mm ² / s and / or its hydride based on the total amount of the base oil, and (C) 100 (D) a weight average molecular weight of 5,000 or more, 200 to a base oil obtained by blending 5 to 20% by mass of an ester base oil having a kinematic viscosity at ² ° C. of ² to 10 mm ² / s based on the total amount of the base oil composition A lubricating oil composition for a gear unit for automobiles having a kinematic viscosity at 100 ° C. of 10 mm ² / s or less, comprising a poly (meth) acrylate viscosity index improver of 1,000 or less.
(2) In the lubricating oil composition, the poly-α-olefin of the component (B) has a kinematic viscosity at 100 ° C. of (B-1) 3.5 mm ² / s to 15 mm ² / s (B -2) It is preferable that it is a mixture of at least two kinds of poly-α-olefins and / or hydrides thereof of more than 15 mm ² / s and not more than 160 mm ² / s.
( 3 ) The (C) ester base oil is preferably a polyhydric alcohol ester base oil.
( 4 ) In the lubricating oil composition, the (D) component poly (meth) acrylate viscosity index improver is preferably (D-1) a dispersed poly (meth) acrylate viscosity index improver. .
( 5 ) In the lubricating oil composition, the (D) component poly (meth) acrylate viscosity index improver is (D-2) a structural unit derived from a monomer represented by the general formula (1). A non-dispersed poly (meth) acrylate viscosity index improver is preferably included.

(In the general formula (1), R ¹ represents hydrogen or a methyl group, and R ² represents a hydrocarbon group having 1 to 30 carbon atoms.)

The lubricating base oil in the lubricating oil composition of the present invention has at least (A) a kinematic viscosity at 100 ° C. of ² to 6 mm ² / s,% CA of 0.5% or less, and tertiary carbon content of 7% or more. Mineral base oil comprising at least one kind and (B) a poly-α-olefin having a kinematic viscosity at 100 ° C. of 6 mm ² / s or more and 160 mm ² / s or less and / or a hydride thereof in a base oil total amount of 2 to 2 40% by mass and (C) 5 to 20% by mass of an ester base oil having a kinematic viscosity of ² to 10 mm ² / s at 100 ° C. based on the total amount of the base oil composition .

The lubricating base oil of component (A) needs to have a kinematic viscosity at 100 ° C. of 2 mm ² / s or more, preferably 2.5 mm ² / s or more, more preferably 3 mm ² / s or more. . Moreover, it is required that it is 6 mm < ² > / s or less, Preferably it is 5.5 mm < ² > / s or less, More preferably, it is 5 mm < ² > / s or less, More preferably, it is 4.5 mm < ² > / s or less.
When the kinematic viscosity at 100 ° C. of the lubricating base oil of the component (A) is less than 2 mm ² / s, it is not preferable because extreme reliability and the fatigue life of the bearing are remarkably reduced, thereby reducing the reliability of the apparatus. On the other hand, if it exceeds 6 mm ² / s, the energy saving performance decreases due to the increase in viscosity.

The% CA of the lubricating base oil of component (A) must be 0.5% or less, preferably 0.3% or less, and more preferably 0.2% or less. By setting the% CA of the lubricating base oil of component (A) to 0.5% or less, a composition having excellent oxidation stability can be obtained.
In addition,% CA as used in the field of this invention means the percentage with respect to the total carbon number of the aromatic carbon number calculated | required by the method (ndM ring analysis) based on ASTM D 3238-85.

% CN of the lubricating base oil of component (A) is preferably 15% or less, more preferably 12% or less, further preferably 10% or less, and more preferably 9% or less. More preferably, it is most preferably 8% or less. Further, it is preferably 3% or more, more preferably 4% or more, further preferably 5% or more, more preferably 6% or more, and most preferably 7% or more. .
When the% CN of the lubricating base oil of the component (A) is less than 3%, the metal fatigue life is not sufficient, and when it exceeds 15%, the oxidation stability and the viscosity index decrease.
In addition,% CN as used in the field of this invention means the percentage with respect to the total carbon number of the carbon number which comprises the naphthene ring structure calculated | required by the method (ndM ring analysis) based on ASTM D 3238-85.

The tertiary carbon content of the component (A) lubricating base oil must be 7% or more. Here, the tertiary carbon content is the ratio of the tertiary carbon to the total amount of the constituent carbon, and the tertiary carbon (> CH--) with respect to the total integrated intensity of all the carbons measured by ¹³ C-NMR. ) Means the percentage of the total integrated intensity of the signal due to carbon atoms.
In the present invention, at the time of ¹³ C-NMR measurement, 0.5 g of a sample diluted with 3 g of deuterated chloroform was used as a sample, the measurement temperature was room temperature, and the resonance frequency was 100 MHz. Moreover, the measuring method used the coupling method with a gate. However, other methods may be used as long as equivalent results can be obtained.

  According to the above analysis, (a) the sum of the integral intensities of about 10-50 ppm of chemical shift (sum of the integral intensities attributable to the total carbon of the hydrocarbon), and (b) the chemical shift of about 27.9-28.1 ppm, 28. Integral intensities of 4-28.6 ppm, 32.6-33.2 ppm, 34.4-34.6 ppm, 37.4-37.6 ppm, 38.8-39.1 ppm, and 40.4-40.6 ppm Ratio of (b) when (a) is taken as 100%, and the total of the total intensities (total of the integral strengths attributed to tertiary carbon and naphthene tertiary carbon with a methyl group, ethyl group and other branched groups) is measured. (%) Was calculated. The ratio of (b) indicates the ratio of all tertiary carbon atoms to all carbon atoms constituting the base oil.

  In the present invention, the proportion of tertiary carbon in the total amount of constituent carbon of the lubricating base oil needs to be 7% or more, preferably 7.3% or more, more preferably 7.6% or more, More preferably, it is 8% or more. Moreover, it is preferable that it is 10% or less, More preferably, it is 9.5% or less, More preferably, it is 9% or less. When the proportion of tertiary carbon is less than 7%, the amount of intramolecular branching is not sufficient, and the increase in viscosity at low temperatures is large, and when it exceeds 10%, there are too many branches and the viscosity index is low. Therefore, it is not preferable.

As long as the component (A) has the above properties, the production method is not particularly limited. Specifically, the base oils (1) to (8) shown below are used as raw materials, and the raw oils and / or the The base oil obtained by refine | purifying the lubricating oil fraction collect | recovered from raw material oil with a predetermined | prescribed refinement | purification method, and collect | recovering lubricating oil fractions can be mentioned.
(1) Distilled oil by atmospheric distillation of paraffinic crude oil and / or mixed base crude oil (2) Distilled oil by vacuum distillation of atmospheric distillation residue of paraffinic crude oil and / or mixed base crude oil ( WVGO)
(3) Wax (such as slack wax) obtained by the lubricant dewaxing process and / or synthetic wax (Fischer-Tropsch wax, GTL wax, etc.) obtained by the gas-liquid (GTL) process, etc.
(4) One or two or more mixed oils selected from base oils (1) to (3) and / or mild hydrocracking treatment oils of the mixed oils (5) selected from base oils (1) to (4) 2 or more kinds of mixed oils (6) Base oil (1), (2), (3), (4) or (5) debris oil (DAO)
(7) Mild hydrocracking treatment oil (MHC) of base oil (6)
(8) Two or more mixed oils selected from base oils (1) to (7)

  The above-mentioned predetermined purification methods include hydrorefining such as hydrocracking and hydrofinishing; solvent refining such as furfural solvent extraction; dewaxing such as solvent dewaxing and catalytic dewaxing; acid clay and activated clay White clay purification; chemical (acid or alkali) cleaning such as sulfuric acid cleaning and caustic soda cleaning is preferable. In the present invention, one of these purification methods may be performed alone, or two or more may be combined. Moreover, when combining 2 or more types of purification methods, the order in particular is not restrict | limited, It can select suitably.

Furthermore, as the lubricating base oil according to the present invention, the following base oil obtained by subjecting a base oil selected from the base oil (3) or a lubricating oil fraction recovered from the base oil to the predetermined treatment ( 9) or (10) is particularly preferred.
(9) The base oil selected from the base oils (1) to (8) or the lubricating oil fraction recovered from the base oil is hydrocracked and recovered from the product or the product by distillation or the like. Hydrocracked mineral oil obtained by performing dewaxing treatment such as solvent dewaxing or catalytic dewaxing on the lubricating oil fraction, or distillation after the dewaxing treatment (10) The above base oils (1) to (8) ) Or a lubricating oil fraction recovered from the base oil is hydroisomerized, and the product or the lubricating oil fraction recovered from the product by distillation or the like is subjected to solvent dewaxing or catalytic dewaxing. Hydroisomerized mineral oil obtained by performing dewaxing treatment such as or by distillation after the dewaxing treatment

When obtaining the lubricating base oil of (9) or (10) above, as the dewaxing step, the thermal / oxidative stability and low temperature viscosity characteristics can be further enhanced, and the fatigue prevention performance of the lubricating oil composition is further enhanced. It is particularly preferable to include a contact dewaxing step.
Moreover, when obtaining the lubricating base oil of (9) or (10) above, a solvent refining treatment and / or a hydrofinishing treatment step may be further provided as necessary.

  In the case of catalytic dewaxing (catalyst dewaxing), the hydrocracking / isomerization product oil is reacted with hydrogen in the presence of a suitable dewaxing catalyst under conditions effective to lower the pour point. In catalytic dewaxing, some of the high-boiling substances in the cracking / isomerization product are converted to low-boiling substances, the low-boiling substances are separated from the heavier base oil fraction, and the base oil fraction is fractionated. Two or more kinds of lubricating base oils are obtained. The low-boiling substances can be separated before obtaining the target lubricating base oil or during fractional distillation.

  The dewaxing catalyst is not particularly limited as long as it can lower the pour point of the cracked / isomerized product oil, but the desired lubricating base oil is obtained from the cracked / isomerized product oil in a high yield. Those that can be used are preferred. As such a dewaxing catalyst, a shape selective molecular sieve (molecular sieve) is preferable, and specifically, ferrierite, mordenite, ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-22 ( And theta aluminophosphates (SAPO) and the like. These molecular sieves are preferably used in combination with a catalytic metal component, and more preferably in combination with a noble metal. A preferable combination includes, for example, a composite of platinum and H-mordenite.

The dewaxing conditions are not particularly limited, but the temperature is preferably 200 to 500 ° C., and the hydrogen pressure is preferably 10 to 200 bar (1 MPa to 20 MPa). Also, in the case of flow-through reactor, H2 processing speed is preferably 0.1~10kg / l / hr, LHSV is preferably 0.1~10h ^-1, 0.2~2.0h ^-1 are more preferred. Dewaxing refers to a substance having an initial boiling point of 350 to 400 ° C., usually 40% by mass or less, preferably 30% by mass or less, contained in the cracked / isomerized product oil, having a boiling point lower than the initial boiling point. It is preferable to carry out the conversion to a substance having the same.

  In the case of catalytic dewaxing (catalyst dewaxing), the hydrocracking / isomerization product oil is reacted with hydrogen in the presence of a suitable dewaxing catalyst under conditions effective to lower the pour point. In catalytic dewaxing, some of the high-boiling substances in the cracking / isomerization product are converted to low-boiling substances, the low-boiling substances are separated from the heavier base oil fraction, and the base oil fraction is fractionated. Two or more kinds of lubricating base oils are obtained. The low-boiling substances can be separated before obtaining the target lubricating base oil or during fractional distillation.

  The mineral oil base oil of component (A) is not particularly limited as long as the kinematic viscosity at 100 ° C.,% CA and tertiary carbon content satisfy the above-mentioned requirements, but the hydrocracked mineral oil base Oil is preferred. A wax isomerized isoparaffin base oil obtained by isomerizing a raw material containing 50% by mass or more of a wax such as petroleum-based or Fischer-Tropsch synthetic oil is also preferably used. These can be used alone or in any mixture, but it is preferable to use a wax isomerized base oil alone.

  The viscosity index of the lubricating base oil of component (A) is not particularly limited, but is preferably 100 or more, more preferably 120 or more, still more preferably 130 or more, and particularly preferably 140 or more. 200 or less, preferably 160 or less. By setting the viscosity index to 100 or more, it is possible to obtain a composition exhibiting favorable viscosity characteristics from a low temperature to a high temperature. On the other hand, if the viscosity index is too high, the effect on fatigue life is small.

  Although there is no restriction | limiting in particular about the aniline point of (A) component, It is preferable that it is 90 degreeC or more at the point which can obtain the lubricating oil composition excellent in a low-temperature viscosity characteristic and fatigue life, More preferably, it is 100 degreeC or more, More preferably, it is 110 degreeC or more, Most preferably, it is 115 degreeC or more. Further, the upper limit is not particularly limited, and may be 130 ° C. or higher as one aspect of the present invention, but is preferably 125 ° C. or lower because it is more excellent in solubility of additives and sludge and more excellent in compatibility with a sealing material. It is.

  Further, the sulfur content of the lubricating base oil of component (A) is not particularly limited, but is preferably 0.05% by mass or less, more preferably 0.01% by mass or less, More preferably, it is 0.005 mass% or less. A composition superior in oxidation stability can be obtained by reducing the sulfur content of the component (A).

The content of the component (A) in the base oil is preferably 40% by mass or more, more preferably 50% by mass or more, further preferably 60% by mass or more, based on the total amount of the base oil composition. Preferably it is 90 mass% or less, More preferably, it is 80 mass% or less, More preferably, it is 70 mass% or less.
If the amount is less than the above range, the viscosity temperature characteristics due to this component are not sufficiently exhibited. If the amount is too large, the amount of the component (B) described later decreases, and the fatigue life and low temperature viscosity characteristic effect due to the combination with the component (B) decreases. To do.

The lubricating base oil of component (B) in the lubricating oil composition of the present invention is a poly-α-olefin having a kinematic viscosity at 100 ° C. of 6 mm ² / s to 160 mm ² / s and / or hydrogenation thereof. .

  As the poly-α-olefin of component (B), typically, an oligomer or co-oligomer of an α-olefin having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms, particularly preferably 8 to 12 carbon atoms is preferable.

  The production method of poly-α-olefin is not particularly limited. For example, a complex of aluminum trichloride or boron trifluoride with water, alcohol (ethanol, propanol, butanol, etc.), carboxylic acid or ester, Ziegler-Natta system or metallocene The method of superposing | polymerizing an alpha olefin in presence of a polymerization catalyst like a catalyst is mentioned.

The (B) component poly-α-olefin has a kinematic viscosity at 100 ° C. of (B-1) 3.5 mm ² / s to 15 mm ² / s, and (B-2) more than 15 mm ² / s to 160 mm ^2. It is preferably a mixture of at least two poly-α-olefins of / s or less and / or hydrides thereof.

The kinematic viscosity at 100 ° C. of the poly-α-olefin of the component (B-1) is preferably 4 mm ² / s or more, more preferably 5 mm ² / s or more, and 7 mm ² / s or more. Is more preferable, and it is most preferable that it is 9 mm < ² > / s or more. Also, preferably not more than 13 mm ² / s, more preferably at most 11 mm ² / s. By blending a poly-α-olefin with a kinematic viscosity at 100 ° C of 3.5 to 15 mm ² / s, not only the bearing fatigue life and gear fatigue life are remarkably improved, but also the fluidity at low temperature is greatly improved. Is done.

The kinematic viscosity at 100 ° C. of the (B-2) component poly-α-olefin is preferably 20 mm ² / s or more, more preferably 30 mm ² / s or more, and 35 mm ² / s or more. Is more preferable. Also, preferably not more than 120 mm ² / s, and even more preferably more preferably 80 mm ² / s or less, or less 60 mm ² / s. By blending a poly-α-olefin having a kinematic viscosity at 100 ° C. of more than 15 mm ² / s and not more than 160 mm ² / s, not only the bearing fatigue life and gear fatigue life are remarkably improved, but also the viscosity index of the composition is increased. Greatly improved.

  In the present invention, the content of the poly-α-olefin as the component (B) is 2 to 40% by mass based on the total amount of the base oil composition, but is preferably 5% by mass or more, and preferably 10% by mass or more. More preferably. On the other hand, from the viewpoint of sealing material compatibility, it is preferably 35% by mass or less, and more preferably 30% by mass or less.

  In the present invention, the content of the poly-α-olefin as the component (B-1) is not particularly limited, but is preferably 3% by mass or more, more preferably 7% by mass or more based on the total amount of the base oil. 10 mass% or more is more preferable. On the other hand, from the viewpoint of compatibility with the sealing material, the content is preferably 20% by mass or less, and more preferably 15% by mass or less.

  In the present invention, the content of the poly-α-olefin as the component (B-2) is not particularly limited, but is preferably 5% by mass or more based on the total amount of the base oil, more preferably 7% by mass or more. 10 mass% or more is more preferable. On the other hand, from the viewpoint of compatibility with the sealing material, the content is preferably 20% by mass or less, and more preferably 15% by mass or less.

  In the present invention, from the viewpoint of low-temperature viscosity characteristics, the mass ratio ((B-1) / (B-2)) of the component (B-1) to the component (B-2) is 0.1 or more. Is more preferable, 0.2 or more is more preferable, and 0.3 or more is further preferable. Moreover, it is preferable to set it as 1.2 or less from a viewpoint of a viscosity index, 1.0 or less is more preferable, and 0.8 or less is further more preferable.

In the lubricating oil composition of the present invention, an ester base oil having a kinematic viscosity at 100 ° C. of ² to 10 mm ² / s as a base oil, in addition to the components (A) and (B). It is preferable to mix.

The ester referred to here is an organic acid ester, and specific examples thereof include esters of monohydric alcohols or polyhydric alcohols with monobasic acids or polybasic acids shown 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) polyhydric alcohol and polybasic acid (E) a mixture of a monohydric alcohol and a polyhydric alcohol, a mixed ester of a polybasic acid (f) a mixed ester of a polyhydric alcohol and a mixture of a monobasic acid and a polybasic acid (g) Mixed ester of a mixture of alcohol and polyhydric alcohol with a mixture of monobasic acid and polybasic acid

Examples of the monohydric alcohol or polyhydric alcohol include monohydric alcohols or polyhydric alcohols having a hydrocarbon group having 1 to 30 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 6 to 18 carbon atoms. .
Examples of the monobasic acid or polybasic acid include monobasic acids or polybasic acids having a hydrocarbon group having 1 to 30 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 6 to 18 carbon atoms. It is done.
Examples of the hydrocarbon group having 1 to 30 carbon atoms include hydrocarbon groups such as alkyl groups, alkenyl groups, cycloalkyl groups, alkylcycloalkyl groups, aryl groups, alkylaryl groups, and arylalkyl groups.

  The alkyl group is preferably an alkyl group having 4 to 20 carbon atoms, particularly preferably an alkyl group having 6 to 18 carbon atoms. The alkenyl group is preferably an alkenyl group having 4 to 20 carbon atoms, particularly preferably an alkenyl group having 6 to 18 carbon atoms.

  Moreover, as said monohydric alcohol, C1-C30 monohydric alkyl alcohol (These alkyl groups may be linear or branched); ethenol, propenol, butenol, Monovalent alkenyl alcohols having 2 to 40 carbon atoms such as hexenol, octenol, decenol, dodecenol, octadecenol (oleyl alcohol, etc.) (these alkenyl groups may be linear or branched, The position of the double bond is also arbitrary.) And a mixture thereof.

  Examples of the polyhydric alcohols include divalent alkyl or alkenyl diols having 2 to 30 carbon atoms (the alkyl group or alkenyl group may be linear or branched, and the position of the double bond of the alkenyl group is arbitrary. The substitution position of the hydroxyl group is also arbitrary.); Trimethylol alkanes such as glycerin, trimethylolethane, trimethylolpropane, trimethylolbutane, erythritol, pentaerythritol, 1,2,4-butanetriol, 1, 3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, adonitol, arabitol, xylitol, mannitol, etc., and polymers or condensates thereof (for example, Diglycerin, triglycerin, tetraglycerin, etc. Condensation compounds such as 2-8 mer of phosphorus, 2-8 mer of trimethylol propane such as ditrimethylol propane, 2-4 mer of pentaerythritol such as dipentaerythritol, sorbitan, sorbitol glycerin condensate (Intramolecular condensation compound, intermolecular condensation compound or self-condensation compound)) and the like.

  In addition, the alcohols are added with an alkylene oxide having 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, or a polymer or copolymer thereof, and the hydroxyl group of the alcohol is hydrocarbyl etherified or hydrocarbyl esterified. You may use what you did. Examples of the alkylene oxide 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-1 -Methylpropane, 1,2-epoxyheptane, 1,2-epoxyhexane and the like. 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 types of alkylene oxide are used, the polymerization mode of the oxyalkylene group is not particularly limited, and may be random copolymerized or block copolymerized. Moreover, when adding an alkylene oxide to the polyhydric alcohol which has 2-6 hydroxyl groups, you may make it add to all the hydroxyl groups, and you may make it add only to one part hydroxyl group.

  Further, as the monobasic acid, a fatty acid having a hydrocarbon group having 1 to 30 carbon atoms is 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 heptane Acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched decanoic acid, linear or branched undecanoic acid, linear or branched dodecane Acid, linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched hexadecanoic acid, linear or branched heptadecane Acid, linear or branched octadecanoic acid, linear or branched hydroxyoctadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, linear or branched Henicosanoic acid, linear or branched Saturated fatty acids such as cosanoic acid, linear or branched tricosanoic acid, 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 nonenoic 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, Linear or branched hexadecenoic acid, linear or branched heptadecenoic acid, linear or branched octadecenoic acid, linear or branched hydroxyoctadecenoic acid, linear or branched nonadecene Acid, linear or branched Unsaturated fatty acids such as cocenoic acid, linear or branched heicosenoic acid, linear or branched docosenoic acid, linear or branched tricosenoic acid, linear or branched tetracosenoic acid, and the like And the like.

  The polybasic acid may be a saturated or unsaturated aliphatic dicarboxylic acid having 2 to 30 carbon atoms (the saturated aliphatic or unsaturated aliphatic may be linear or branched, and the position of the unsaturated bond). ); Saturated or unsaturated aliphatic tricarboxylic acids such as propanetricarboxylic acid, butanetricarboxylic acid, pentanetricarboxylic acid, hexanetricarboxylic acid, heptanetricarboxylic acid, octanetricarboxylic acid, nonanetricarboxylic acid, decanetricarboxylic acid, etc. (these Saturated aliphatic or unsaturated aliphatic may be linear or branched, and the position of unsaturated bond is arbitrary.); Saturated or unsaturated aliphatic tetracarboxylic acid (these saturated aliphatic or unsaturated fatty acids) The group may be linear or branched, and the position of the unsaturated bond is arbitrary.).

  As the ester base oil of component (C) in the present invention, one or two or more ester base oils that satisfy the above specifications can be mixed and used, and as long as the mixture satisfies the above specifications, the above You may mix and use 1 type, or 2 or more types of ester base oil which satisfy | fills prescription | regulation, and ester base oil which does not satisfy | fill the said prescription | regulation.

  The (C) ester base oil in the present invention is preferably a polyhydric alcohol ester base oil, specifically, trimethylolalkanes such as trimethylolpropane and trimethylolbutane, erythritol, pentaerythritol, and 6 to 18 carbon atoms. , Preferably a monovalent saturated or unsaturated fatty acid having 12 to 18 carbon atoms (these fatty acids may be linear or branched, and the position of the double bond is arbitrary), a polyhydric aliphatic alcohol, It is particularly preferred to be selected from these esters.

Preferably the kinematic viscosity at 100 ° C. of the ester-based base oil component (C) is 2 to 10 mm ² / s, more preferably 3 to 8 mm ² / s. By blending an ester base oil having a kinematic viscosity of ² to 10 mm ² / s at 100 ° C., bearing fatigue life and gear fatigue life are remarkably improved.

In the present invention, the component (B) and (C) to the other components, it is preferable that kinematic viscosity at 100 ° C. does not include a beyond 10 mm ² / base oil of less than s ^6mm 2 / s. This is because including this base oil tends to reduce the fatigue life.

  Although there is no restriction | limiting in particular about the pour point of the ester base oil of (C) component, Preferably it is -20 degrees C or less, More preferably, it is -30 degrees C or less, Most preferably, it is -40 degrees C or less. By setting the pour point to −20 ° C. or less, it is possible to obtain a composition that is excellent in low friction property in a low temperature region and excellent in startability or fuel saving performance immediately after the start.

  In the present invention, the content of the ester base oil of the component (C) is not particularly limited, but is preferably 5% by mass or more based on the total amount of the base oil, more preferably 7% by mass or more, More preferably, it is 10 mass% or more. On the other hand, it is preferable to set it as 20 mass% or less from a viewpoint of sealing material swelling performance, and it is more preferable to set it as 15 mass% or less.

The lubricating base oil in the lubricating oil composition of the present invention has a kinematic viscosity at 100 ° C. of 3 mm ² / s or higher, preferably 4 mm ² / s or higher, more preferably 5 mm ² / s or higher, or 8 mm ² / s or lower. The lubricating base oil is preferably adjusted to 7 mm ² / s or less, more preferably 6.5 mm ² / s or less.
The viscosity of the base oil greatly affects the fatigue life, and the higher the viscosity, the longer the life is basically. However, since the low temperature viscosity deteriorates, an appropriate viscosity range exists.

  The lubricating oil composition of the present invention contains (D) a poly (meth) acrylate viscosity index improver having a weight average molecular weight of 5,000 or more and 200,000 or less.

  The component (D) in the present invention is a poly (meth) acrylate viscosity index improver having a structural unit represented by the following general formula (1).

In the general formula (1), R ¹ is hydrogen or a methyl group, preferably a methyl group, and R ² is a hydrocarbon group having 1 to 30 carbon atoms. Note that the structural units of the poly (meth) acrylate, it is preferable that the carbon number of R ² is 20 or more structural units that contain more than 1 mol%.

  Although the production method of the poly (meth) acrylate is arbitrary, for example, in the presence of a polymerization initiator such as benzoyl peroxide, a mixture of monomers described later in an appropriate hydrocarbon solvent such as benzene or toluene. An aromatic solvent may be used, and it can be easily obtained by radical solution polymerization in a solution of a simple petroleum solvent such as a lubricating base oil.

The weight average molecular weight (M _w ) of the poly (meth) acrylate viscosity index improver as the component (D) is 5,000 or more and 200,000 or less. More preferably, it is 10,000 or more, more preferably 20,000 or more, and 200,000 or less, preferably 100,000 or less, more preferably 70,000 or less, and further preferably 50,000 or less.
When the weight average molecular weight is less than 5,000, the effect of improving viscosity temperature characteristics and the effect of improving the viscosity index are small, and when the weight average molecular weight exceeds 200,0000, shear stability, solubility in base oil, storage There is a risk of poor stability.

In addition, the weight average molecular weight here is 150-C made by Waters.
Two columns of GHSHR-M (7.8 mm ID × 30 cm) manufactured by Tosoh Corporation are used in series in the ALC / GPC apparatus, and the solvent is tetrahydrofuran, temperature 23 ° C., flow rate 1 mL / min, sample concentration 1% by mass, sample An injection amount of 75 μL means a polystyrene-reduced weight average molecular weight measured with a detector differential refractometer (RI).

The content of the (D) viscosity index improver in the lubricating oil composition of the present invention is 1% by mass or more based on the total amount of the composition, preferably 2% by mass or more, and preferably 20% by mass or less. More preferably, it is 15 mass% or less, More preferably, it is 10 mass% or less, Most preferably, it is 8 mass% or less.
(D) When the content of the viscosity index improver is less than 1% by mass, the effect of improving the viscosity index and the effect of reducing the product viscosity are reduced, and thus there is a possibility that the fuel economy cannot be improved. Also, if it exceeds 20% by mass, the product cost will increase significantly and the viscosity of the base oil will need to be reduced. Therefore, the lubrication performance under severe lubrication conditions (high temperature and high shear conditions) will be reduced and wear will be reduced. Failures such as seizure, seizure and fatigue failure may be the cause.

  In the lubricating oil composition of the present invention, the (D) component poly (meth) acrylate viscosity index improver is preferably (D-1) a dispersed poly (meth) acrylate viscosity index improver.

  The (D-1) dispersed poly (meth) acrylate viscosity index improver in the present invention includes a structural unit derived from a monomer represented by the following general formula (2) and / or (3).

In the general formula (2), R ³ is hydrogen or a methyl group, preferably a methyl group, R ⁴ is an alkylene group having 1 to 30 carbon atoms, E ¹ is ¹ to 2 nitrogen atoms, and 0 to 2 oxygen atoms. An amine residue or a heterocyclic residue to be contained is shown, and a represents an integer of 0 or 1.

In the general formula (3), R ⁵ is hydrogen or a methyl group. E ² represents an amine residue or a heterocyclic residue containing 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms.

Specific examples of the group represented by E ¹ and E ² include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, and a benzoylamino group. Morpholino group, pyrrolyl group, pyrrolino group, pyridyl group, methylpyridyl group, pyrrolidinyl group, piperidinyl group, quinonyl group, pyrrolidonyl group, pyrrolidono group, imidazolino group, pyrazino group and the like.

  Specific examples of this include dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, morpholinomethyl methacrylate, morpholinoethyl methacrylate, N-vinylpyrrolidone. And a mixture thereof.

Specifically, the (D-1) dispersion type poly (meth) acrylate viscosity index improver includes the monomer represented by the following general formula (1) and the general formula (D-1a) to (D-1d) It is a copolymer with the polar group-containing monomer of (D-1e) represented by 2) and / or (3).
(D-1a) ^{R 2} is an alkyl group having 1 to 4 carbon atoms (meth) acrylate (D-1b) ^{R 2} is an alkyl group having 5 to 10 carbon atoms (meth) acrylate (D-1c) R ² is an alkyl group having 11 to 19 carbon atoms (meth) acrylate (D-1d) ^{R 2} is a number 20 or more alkyl group having a carbon (meth) acrylate (D-1e) polar group-containing monomer

In the present invention, the composition ratio of monomers in the viscosity index improver (D-1) component is preferably as follows based on the total amount of monomers constituting the poly (meth) acrylate.
(D-1a) component: Preferably it is 25 mol% or more, More preferably, it is 45 mol% or more, More preferably, it is 65 mol% or more, Preferably it is 95 mol% or less, More preferably, it is 90 mol% or less, More preferably, it is 85 mol% or less.
Component (D-1b): preferably 0 mol% or more, preferably 50 mol% or less, more preferably 20 mol% or less.
(D-1c) component: Preferably it is 0 mol% or more, More preferably, it is 5 mol% or more, More preferably, it is 10 mol% or more, Preferably it is 60 mol% or less, More preferably, it is 45 mol% or less, More preferably, it is 30 mol% or less.
(D-1d) component: Preferably it is 1 mol% or more, More preferably, it is 3 mol% or more, More preferably, it is 5 mol% or more, Preferably it is 55 mol% or less, More preferably, it is 35 mol% or less, More preferably, it is 15 mol% or less.
(D-1e) component: 0.1 mol% or more, preferably 0.3 mol% or more, more preferably 0.5 mol% or more, further preferably 1 mol% or more, most preferably 2 mol% or more, preferably 20 mol% or less, More preferably, it is 10 mol% or less, More preferably, it is 5 mol% or less.

  By setting it as this composition, it can be set as the poly (meth) acrylate viscosity index improver effective in a low-temperature viscosity characteristic and fatigue life.

  In the lubricating oil composition of the present invention, the (D) component poly (meth) acrylate viscosity index improver contains (D-2) a structural unit derived from a monomer represented by the general formula (1). It is preferable that it is a type | mold poly (meth) acrylate type viscosity index improver.

The (D-2) non-dispersed poly (meth) acrylate viscosity index improver is specifically represented by the following general formula (1) consisting of the following (D-2a) to (D-2c) (D-2d). ) And a monomer.
(D-2a) ^{R 2} is an alkyl group having 1 to 4 carbon atoms (meth) acrylate (D-2b) ^{R 2} is an alkyl group having 5 to 10 carbon atoms (meth) acrylate (D-2c) R ² is an alkyl group (meth) acrylate (D-2d) ^{R 2} is an alkyl group having at least 20 carbon atoms 11 to 19 carbon atoms (meth) acrylate

In the present invention, the composition ratio of the monomer in the viscosity index improver (D-2) component is preferably as follows based on the total amount of monomers constituting the poly (meth) acrylate.
Component (D-2a): preferably 25 mol% or more, more preferably 45 mol% or more, still more preferably 65 mol% or more, preferably 95 mol% or less, more preferably 90 mol% or less, still more preferably 85 mol% or less.
Component (D-2b): preferably 0 mol% or more, preferably 50 mol% or less, more preferably 20 mol% or less.
(D-2c) component: Preferably it is 0 mol% or more, More preferably, it is 5 mol% or more, More preferably, it is 10 mol% or more, Preferably it is 60 mol% or less, More preferably, it is 45 mol% or less, More preferably, it is 30 mol% or less.
Component (D-2d): preferably 0.1 mol% or more, more preferably 0.5 mol% or more, more preferably 1 mol% or more, particularly preferably 2 mol% or more, most preferably 4 mol% or more, preferably 50 mol% or less. More preferably, it is 35 mol% or less, More preferably, it is 20 mol% or less, Most preferably, it is 15 mol% or less.

  By setting it as this composition, it can be set as the poly (meth) acrylate viscosity index improver effective in a low-temperature viscosity characteristic and fatigue life.

  In the present invention, the component (D-1) and the component (D-2) can be mixed and used. However, the use of the component (D-1) or the component (D-2) alone is more effective for extending the fatigue life, and the component (D-1) is more preferably used alone.

  The lubricating oil composition of the present invention can contain other viscosity index improvers in addition to the viscosity index improver described above as a viscosity index improver. For example, non-dispersed or dispersed poly (meth) acrylates other than those mentioned above, non-dispersed or dispersed ethylene-α-olefin copolymers or hydrides thereof, polyisobutylene or hydrides thereof, styrene-diene hydrogenated copolymer Examples of the polymer include styrene-maleic anhydride copolymer and polyalkylstyrene.

Moreover, it is preferable that the lubricating oil composition of this invention adds (D-3) poly (meth) acrylate type pour point depressant separately from a viscosity index improver. This structure is basically the same as the component (D-2), but does not include the component (D-2d), and the composition has a larger amount of the component (D-2c).
(D-3) The weight average molecular weight of the poly (meth) acrylate pour point depressant is preferably 50,000 or more and 200,000 or less. If it is less than 50,000, the pour point depressing property is poor, and if it exceeds 200,000, the shear stability decreases, which is not preferable.
(D-3) The addition amount of the poly (meth) acrylate pour point depressant is preferably 0.05% by mass or more and 5% by mass or less based on the total amount of the composition. 0.1 mass% or more is more preferable, and 3 mass% or less is more preferable. If it is less than 0.05% by mass, the pour point depressing property is poor.

  The lubricating oil composition of the present invention preferably contains (E) zinc dialkyldithiophosphate (hereinafter referred to as “component (E)”). Examples of the zinc dialkyldithiophosphate include compounds represented by the following general formula (4).

In the general formula (4), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrocarbon group having 1 to 18 carbon atoms. Examples of such hydrocarbon groups include a methyl group and an ethyl group. N-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, linear or branched pentyl group, linear or branched hexyl group, linear or branched A heptyl group, a linear or branched octyl group, a linear or branched nonyl group, a linear or branched decyl group, a linear or branched undecyl group, a linear or branched dodecyl group, a straight Linear or branched tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, linear or branched hexadecyl group, linear or branched heptadecyl group, linear or branched Such as octadecyl group Is an alkyl group of prime numbers from 1 to 18.

  Specific examples of particularly preferable zinc dialkyldithiophosphate as component (E) include, for example, zinc diisopropyldithiophosphate, zinc diisobutyldithiophosphate, zinc di-sec-butyldithiophosphate, zinc di-sec-pentyldithiophosphate, di- zinc n-hexyldithiophosphate, zinc di-sec-hexyldithiophosphate, zinc di-n-octyldithiophosphate, zinc di-2-ethylhexyldithiophosphate, zinc di-n-decyldithiophosphate, di-n-dodecyldithiophosphate Zinc, zinc diisotridecyl dithiophosphate, and mixtures thereof can be exemplified. Among these, zinc di-sec-alkyldithiophosphates such as zinc di-sec-butyldithiophosphate, zinc di-sec-pentyldithiophosphate, and zinc di-sec-hexyldithiophosphate are preferable.

  The content of the component (E) in the lubricating oil composition of the present invention is, based on the total amount of the lubricating oil composition, as the amount of zinc metal, the lower limit is 0.02% by mass or more, preferably 0.1% by mass or more. On the other hand, the upper limit is 0.5 mass% or less, preferably 0.4 mass% or less, more preferably 0.3 mass% or less. When the content of the component (E) is less than 0.02% by mass, a remarkable life extension effect and wear resistance cannot be obtained, and when it exceeds 0.5% by mass, the oxidation stability is adversely affected. Therefore, it is not preferable respectively.

  The lubricating oil composition of the present invention preferably contains (F) an alkaline earth metal detergent having a base number of 100 mgKOH / g or more (hereinafter referred to as “component (F)”). Examples of the alkaline earth metal detergent include alkaline earth metal sulfonate, alkaline earth metal phenate, alkaline earth metal salicylate, alkaline earth metal phosphonate, or a mixture thereof.

  More specifically, as the alkaline earth metal sulfonate, for example, an alkaline earth metal salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a molecular weight of 100 to 1500, preferably 200 to 700, In particular, magnesium salts and / or calcium salts are preferably used, and examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid.

  As the petroleum sulfonic acid, those obtained by sulfonating an alkyl aromatic compound of a lubricating oil fraction of mineral oil or so-called mahoganic acid which is produced as a by-product when white oil is produced is used. As the synthetic sulfonic acid, for example, an alkylbenzene production plant used as a raw material for detergents, or an alkylbenzene having a linear or branched alkyl group obtained by alkylating polyolefin with benzene is used as a raw material. Or sulfonated dinonylnaphthalene is used. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, but usually fuming sulfuric acid or sulfuric acid is used.

  More specifically, the alkaline earth metal phenate is an alkylphenol having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms, and reacting the alkylphenol with elemental sulfur. Alkali earth metal salts, especially magnesium salts and / or calcium salts of Mannich reaction products of alkylphenols obtained by reacting alkylphenol sulfide obtained by reacting these alkylphenols with formaldehyde are preferably used.

  More specifically, as the alkaline earth metal salicylate, an alkaline earth metal salt of an alkyl salicylic acid having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms, In particular, magnesium salts and / or calcium salts are preferably used.

  Alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates include alkyl aromatic sulfonic acids, alkylphenols, alkylphenol sulfides, Mannich reaction products of alkylphenols, alkylsalicylic acid, etc. Neutral salt (normal salt) obtained by reacting with metal bases such as metal oxides and hydroxides, or once replacing alkali metal salts such as sodium salts and potassium salts with alkaline earth metal salts ), As well as heating these neutral salts (normal salts) and excess alkaline earth metal salts or alkaline earth metal bases (hydroxides or oxides of alkaline earth metals) in the presence of water. In the presence of carbon dioxide, boric acid or borate. ) An overbased salts obtained by reaction with a base such as hydroxides of alkali metals or alkaline earth metals (overbased salts) are also included. These reactions are usually carried out in a solvent (an aliphatic hydrocarbon solvent such as hexane, an aromatic hydrocarbon solvent such as xylene, a light lubricating base oil).

  Furthermore, the (F) component in the lubricating oil composition of the present invention is preferably an overbased metal detergent containing an excess metal salt, such as carbonate, than the neutral salt. Specifically, the metal ratio, that is, the value obtained by multiplying the number of moles of alkaline earth metal by the valence of 2 divided by the number of moles of soap groups of the metal detergent is preferably 2.5 or more.

In the present invention, as the component (F), one or more metal detergents selected from alkaline earth metal sulfonates, phenates, salicylates and the like can be used in combination.
Among these, alkaline earth metal sulfonates or alkaline earth phenates are preferred in the lubricating oil composition of the present invention. Most preferred is an alkaline earth metal sulfonate. This is because sulfonate is the most excellent in anti-wear performance among the metallic detergents of component (F), and then phenate is excellent.

The total base number of the alkaline earth metal detergent as the component (F) in the lubricating oil composition of the present invention is preferably 100 mgKOH / g or more, more preferably 140 mgKOH / g or more, and further preferably 200 mgKOH. / G or more. Moreover, it is preferable that it is 500 mgKOH / g or less, More preferably, it is 450 mgKOH / g or less, More preferably, it is 400 mgKOH / g or less. When the base number is less than 100 mgKOH / g, the fatigue life extending effect is not recognized. When the base number exceeds 500 mgKOH / g, the lubricating oil composition lacks stability.
The total base number referred to here is 7. JISK2501 “Petroleum products and lubricants-Neutralization number test method”. It means the total base number measured by the perchloric acid method based on

  In the present invention, the content of the component (F) is not particularly limited, but usually it is preferably 0.5% by mass or less in terms of metal element based on the total amount of the composition, and the sulfated ash content of the composition is It is preferable to adjust together with other additives so that it may become 1.2 mass% or less. From such a viewpoint, the upper limit of the content of the metal-based detergent is more preferably 0.3% by mass or less, more preferably 0.25% by mass or less, in terms of metal element, based on the total amount of the composition. Especially preferably, it is 0.2 mass% or less. The lower limit is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and particularly preferably 0.05% by mass or more.

  In addition, although a metal type detergent is usually marketed in the state diluted with light lube base oil etc. and is available, generally the metal content is 1.0-20 mass%. It is desirable to use 2.0 to 16% by mass.

The lubricating oil composition of the present invention preferably contains (G) a sulfurized olefin (hereinafter referred to as (G) component). Examples of the sulfurized olefin include compounds represented by the following general formula (5).
R ¹ -Sx-R ² (5)
In the general formula (5), R ¹ represents an alkenyl group having 2 to 15 carbon atoms, R ² represents an alkyl group or alkenyl group having 2 to 15 carbon atoms, and x represents an integer of 1 to 8.
This compound can be obtained by reacting an olefin having 2 to 15 carbon atoms or a dimer or tetramer thereof with a sulfurizing agent such as sulfur or sulfur chloride. As the olefin, for example, propylene, isobutene, diisobutene and the like are preferably used.

Another form of sulfurized olefin is dihydrocarbyl polysulfide. Dihydrocarbyl polysulfide is a compound represented by the following general formula (6).
R ³ -Sy-R ⁴ (6)
In General Formula (6), R ³ and R ⁴ are each independently an alkyl group having 1 to 20 carbon atoms (including a cycloalkyl group), an aryl group having 6 to 20 carbon atoms, or an aryl having 7 to 20 carbon atoms. Represents an alkyl group, which may be the same or different from each other, and y represents an integer of 2 to 8;

Specific examples of R ³ and R ⁴ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, and various pentyl groups. Groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups, cyclohexyl groups, phenyl groups, naphthyl groups, tolyl groups, xylyl groups, benzyl groups, and phenethyl groups. be able to.

  Specific examples of preferred dihydrocarbyl polysulfides include dibenzyl polysulfide, di-tert-nonyl polysulfide, didodecyl polysulfide, di-tert-butyl polysulfide, dioctyl polysulfide, diphenyl polysulfide, and dicyclohexyl polysulfide. It is done.

  In the present invention, the amount of (G) sulfurized olefin added is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and further preferably 0.5% by mass based on the total amount of the lubricating oil composition. The content is preferably 2% by mass or less, more preferably 1.5% by mass or less. If it is less than 0.1% by mass, the effect of improving seizure resistance is not recognized, and if it exceeds 2% by mass, the oxidation stability of the composition is significantly reduced.

  In order to further improve the performance, the lubricating oil composition of the present invention may contain any additive generally used in lubricating oils depending on the purpose. Examples of such additives include metal detergents other than the overbased metal salt of component (F), ashless dispersants, antiwear agents (or extreme pressure agents), antioxidants, corrosion inhibitors, anticorrosives, and the like. Examples thereof include additives such as rusting agents, demulsifiers, metal deactivators, and antifoaming agents.

  (F) As a metal detergent other than the overbased metal salt of component, a positive salt such as alkali metal / alkaline earth metal sulfonate, alkali metal / alkaline earth metal phenate, and alkali metal / alkaline earth metal salicylate, or the like Mention may be made of basic salts. Examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include magnesium, calcium, and barium. Magnesium or calcium is preferable, and calcium is more preferable.

  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, or these And modified products of boron compounds, carboxylic acids, phosphoric acids, and the like. 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, alkylphenols such as 2-6-di-tert-butyl-4-methylphenol and bisphenols such as methylene-4,4-bisphenol (2,6-di-tert-butyl-4-methylphenol) , Naphthylamines such as phenyl-α-naphthylamine, dialkyldiphenylamines, zinc dialkyldithiophosphates such as zinc di-2-ethylhexyldithiophosphate, (3,5-di-tert-butyl-4-hydroxyphenyl) fatty acid ( (Propionic acid etc.) or (3-methyl-5-tertbutyl-4-hydroxyphenyl) fatty acid (propionic acid etc.) and mono- or polyhydric alcohols such as methanol, octanol, octadecanol, 1,6 hexadiol, neo Pentyl glycol, thiodiethylene glycol, Triethylene glycol, esters of pentaerythritol and the like.

  As the antiwear agent (or extreme pressure agent), any antiwear agent / extreme pressure agent used for lubricating oil can be used in addition to the component (E) of the present invention. For example, sulfur-based, phosphorus-based, sulfur-phosphorus extreme pressure agents and the like can be used. Specifically, phosphites, thiophosphites, dithiophosphites, trithiophosphites Esters, phosphate esters, thiophosphate esters, dithiophosphate esters, trithiophosphate esters, amine salts thereof, metal salts thereof, derivatives thereof, dithiocarbamate, zinc dithiocarbamate, molybdenum dithiocarbamate, disulfide , Polysulfides, and sulfurized fats and oils.

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

  Examples of the rust preventive include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, and alkenyl succinate.

  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 metal deactivators include imidazoline, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis. Examples thereof include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and β- (o-carboxybenzylthio) propiononitrile.

Examples of the antifoaming agent include silicone oil having a kinematic viscosity at 25 ° C. of 1000 to 100,000 mm ² / s, alkenyl succinic acid derivative, ester of polyhydroxy aliphatic alcohol and long chain fatty acid, methyl salicylate and o- Examples thereof include hydroxybenzyl alcohol.

  When these additives are contained in the lubricating oil composition of the present invention, the content thereof is preferably 0.001 to 10% by mass based on the total amount of the lubricating oil composition.

As the friction modifier, any compound usually used as a friction modifier for lubricating oils can be used, but an alkyl group or alkenyl group having 6 to 30 carbon atoms, particularly a linear alkyl group having 6 to 30 carbon atoms. Alternatively, amine compounds, imide compounds, fatty acid esters, fatty acid amides, fatty acid metal salts, and the like having at least one linear alkenyl group in the molecule are preferably used.
Examples of the amine compound include linear or branched, preferably linear aliphatic monoamines having 6 to 30 carbon atoms, linear or branched, preferably linear aliphatic polyamines, or fatty acids thereof. An alkylene oxide adduct of a group amine can be exemplified. Examples of the imide compound include a succinimide having a linear or branched alkyl group or alkenyl group having 6 to 30 carbon atoms and / or a modified compound thereof using carboxylic acid, boric acid, phosphoric acid, sulfuric acid, or the like. . Examples of fatty acid esters include esters of linear or branched, preferably linear, fatty acids having 7 to 31 carbon atoms with aliphatic monohydric alcohols or aliphatic polyhydric alcohols. Examples of fatty acid amides include amides of linear or branched, preferably linear fatty acids having 7 to 31 carbon atoms, and aliphatic monoamines or aliphatic polyamines. Examples of the fatty acid metal salt include an alkaline earth metal salt (magnesium salt, calcium salt, etc.) or zinc salt of a linear or branched, preferably linear fatty acid having 7 to 31 carbon atoms.
In particular, sulfurized fats and oils are preferably used as friction modifiers for manual transmissions. Examples of sulfurized fats and oils include sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, sulfurized soybean oil, and sulfurized rice bran oil; disulfide fatty acids such as sulfurized oleic acid; and sulfurized esters such as methyl sulfide oleate. .

  In the present invention, one or two or more compounds arbitrarily selected from the above friction modifiers can be contained in any amount, but usually the content is based on the total amount of the lubricating oil composition. 0.01-5.0 mass% is preferable, More preferably, it is 0.03-3.0 mass%.

The kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 10 mm ² / s or less, more preferably 9 mm ² / s or less, still more preferably 8 mm ² / s or less. Further, the kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 4 mm ² / s or more, more preferably 5 mm ² / s or more, and further preferably 6 mm ² / s or more.
The kinematic viscosity at 100 ° C. here refers to the kinematic viscosity at 100 ° C. as defined in ASTM D-445. If the kinematic viscosity at 100 ° C. is less than 4 mm ² / s, there is a risk of insufficient lubricity, and if it exceeds 10 mm ² / s, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained. is there.

  The viscosity index of the lubricating oil composition of the present invention is preferably in the range of 130 to 250, more preferably 140 or more, still more preferably 160 or more, and particularly preferably 180 or more. When the viscosity index of the lubricating oil composition of the present invention is less than 130, it may be difficult to improve fuel economy. In addition, when the viscosity index of the lubricating oil composition of the present invention exceeds 250, there is a possibility that the evaporability may be deteriorated, and further problems due to insufficient solubility of the additive and compatibility with the sealing material occur. There is a risk.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these examples.

(Examples 1-9 and Comparative Examples 1-6)
Table 1 shows the amounts and performance of various lubricating base oils and additives. The blending amount (% by mass) of the base oil is based on the total amount of the base oil composition, and the added amount (% by mass) of each additive is based on the total amount of the lubricating oil composition.
About each obtained composition, the fatigue life was evaluated by the fatigue life test shown to the following (1). Moreover, the extreme pressure property after initial and long-term use was evaluated by the extreme pressure property test shown in the following (2). Moreover, the oxidation stability test result shown in (3) was described.

(1) Fatigue life test (a) FZG
Operation was performed under the following conditions using an FZG tester, and the fatigue life of the gears until the gears were pitched was evaluated.
[Conditions] Load stage: 12, oil temperature: 120 ° C., rotation speed: 620 rpm

(2) Extreme pressure test (a) Based on ASTM D2783, the maximum non-seizure load (LNSL) at 1800 rpm of each lubricating oil composition was measured using a high-speed four-ball tester.
(B) Based on ASTM D4172, the wear scar diameter of each lubricating oil composition at 1800 rpm, load 392 N, and test time 1 hour was measured using a high-speed four-ball tester.
(C) In accordance with ASTM D3233, a seizure load at 110 ° C. at 290 rpm of each lubricating oil composition was measured using a Falex testing machine.

(3) Oxidation stability JIS K 2514 The kinematic viscosity ratio was measured according to (Lubricating oil oxidation stability test method for internal combustion engines).

  The lubricating oil composition of the present invention is extremely effective as an unprecedented fuel-saving transmission lubricating oil composition.

Claims (5)

(A) Mineral base oil having a kinematic viscosity at 100 ° C. of ² to 6 mm ² / s,% CA of 0.5% or less and tertiary carbon content of 7% or more, and (B) kinematic viscosity at 100 ° C. of 6 mm. ² / s or more and 160 mm ² / s or less of poly-α-olefin and / or hydride thereof based on the total amount of the base oil, 2 to 40% by mass, and (C) the kinematic viscosity at 100 ° C. is ² to 10 mm ² / s. (D) Poly (meth) acrylate viscosity index having a weight average molecular weight of 5,000 or more and 200,000 or less in a base oil comprising 5 to 20% by mass of an ester base oil based on the total amount of the base oil composition A lubricating oil composition for an automobile gear unit having a kinematic viscosity at 100 ° C. of 10 mm ² / s or less, comprising an improver. The poly-α-olefin of the component (B) has a kinematic viscosity at 100 ° C. of (B-1) 3.5 mm ² / s to 15 mm ² / s and (B-2) more than 15 mm ² / s to 160 mm ^2. 2. The lubricating oil composition according to claim 1, wherein the lubricating oil composition is a mixture of at least two poly-α-olefins of / s or less and / or hydrides thereof. The lubricating oil composition according to claim 1 or 2 , wherein the (C) ester base oil is a polyhydric alcohol ester base oil. Component (D) poly (meth) acrylate based viscosity index improver, any of claims 1 to 3, characterized in that the (D-1) dispersed poly (meth) acrylate based viscosity index improver A lubricating oil composition according to claim 1. The (D) component poly (meth) acrylate viscosity index improver comprises a structural unit derived from the monomer represented by (D-2) general formula (1). The lubricating oil composition according to any one of claims 1 to 3 , wherein the lubricating oil composition is an improver.

(In the general formula (1), R ¹ represents hydrogen or a methyl group, and R ² represents a hydrocarbon group having 1 to 30 carbon atoms.)