JP2014133902A - Lubricant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition with which dynamic viscosities at 40°C and 100°C and HTHS viscosity at 100°C can be sufficiently reduced while retaining the HTHS viscosity at 150°C, and the rise of the friction coefficient in a boundary lubricating area can be sufficiently suppressed, and which has excellent fuel efficiency.SOLUTION: The lubricant composition comprises: a lubricant base oil having a kinetic viscosity at 100°C of 1-20 mm/s; (A) a viscosity index improver having a ratio M1/M2 of 0.20 or more, in which M1 is the total area of peaks between chemical shift 36-38 ppm to the total area of all peaks and M2 is the total area of peaks between chemical shift 64-66 ppm to the total area of all peaks, in a spectrum obtained byC-NMR; (B) a friction regulating agent; and (C) an overbased metal salt obtained by performing overbasing of an oil-soluble metal salt with an alkaline earth metal borate.

Description

  The present invention relates to a lubricating oil composition.

  Conventionally, lubricating oil is used in an internal combustion engine, a transmission, and other mechanical devices in order to make the operation smooth. In particular, lubricating oil (engine oil) for internal combustion engines is required to have high performance as the performance of the internal combustion engine increases, the output increases, and the operating conditions become severe. Therefore, in order to satisfy such required performance, conventional engine oils are blended with various additives such as antiwear agents, metal detergents, ashless dispersants, and antioxidants (for example, Patent Documents 1 to 1 below). 3). In recent years, the fuel-saving performance required for lubricating oil has been increasing, and the application of a high viscosity index base oil and various friction modifiers has been studied (for example, see Patent Document 4 below). .

JP 2001-279287 A JP 2002-129182 A Japanese Patent Laid-Open No. 08-302378 Japanese Patent Laid-Open No. 06-306384

  However, conventional lubricating oils are not always sufficient in terms of fuel economy.

  For example, as a general technique for reducing fuel consumption, reduction of kinematic viscosity of lubricant and improvement of viscosity index (multigrade using a combination of a low viscosity base oil and a viscosity index improver) are known. However, in the case of such a method, due to a decrease in the viscosity of the lubricating oil or the base oil that constitutes the lubricating oil, the lubricating performance under severe lubricating conditions (high temperature and high shear conditions) decreases, and wear, seizure, fatigue There is concern about the occurrence of defects such as destruction. That is, in the conventional lubricating oil, it is difficult to provide sufficient fuel saving while maintaining other practical performance such as durability.

  In order to prevent the above-described problems and maintain fuel durability while providing fuel economy, the HTHS viscosity at 150 ° C. (“HTHS viscosity” is also referred to as “high temperature high shear viscosity”) is high. On the other hand, it is effective to reduce the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C., and the HTHS viscosity at 100 ° C., but it is very difficult to satisfy all these requirements with conventional lubricating oils. Moreover, it is known that the coefficient of friction in the boundary lubrication region where metals are in contact with each other is increased only by reducing the viscosity. In order to improve fuel economy, it is necessary to reduce the friction coefficient in the boundary lubrication region.

  The present invention has been made in view of such circumstances, and sufficiently maintains the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C., and the HTHS viscosity at 100 ° C. while maintaining the HTHS viscosity at 150 ° C. Another object of the present invention is to provide a lubricating oil composition that can sufficiently suppress an increase in the friction coefficient in the boundary lubrication region and is excellent in fuel efficiency.

In order to solve the above-mentioned problem, the present invention provides a lubricating base oil having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s and (A) a spectrum obtained by ¹³ C-NMR, a total area of all peaks. A viscosity index improver in which the ratio M1 / M2 of the total area M1 of peaks between 36 and 38 ppm chemical shift to the total area M2 of peaks between 64 and 66 ppm chemical shift is 0.20 or more, and (B) friction Provided is a lubricating oil composition comprising a regulator and (C) an overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate.

  The (A) viscosity index improver is preferably a poly (meth) acrylate viscosity index improver.

Further, the (A) viscosity index improver preferably has a PSSI of 40 or less and a weight average molecular weight to PSSI ratio of 1 × 10 ⁴ or more.

  Here, “PSSI” as used in the present invention is based on ASTM D 6022-01 (Standard Practition for Calculation of Permanent Shear Stability Index) Permanent Shear Stability Index calculated based on data measured by European Diesel Injector Apparatus.

  The (B) friction modifier is preferably an organic molybdenum compound.

  In addition, (C) an overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate is an overbase obtained by overbasing an alkaline earth metal salicylate with an alkaline earth metal borate. Preferably, it is a basic alkaline earth metal salicylate.

  As described above, according to the present invention, while maintaining the HTHS viscosity at 150 ° C., the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C., and the HTHS viscosity at 100 ° C. can be sufficiently lowered, and boundary lubrication can be achieved. An increase in the friction coefficient in the region can be sufficiently suppressed, and a lubricating oil composition excellent in fuel economy can be provided. For example, according to the lubricating oil composition of the present invention, a desired HTHS viscosity at 150 ° C. can be obtained without using a synthetic oil such as a poly-α-olefin base oil or an ester base oil, or a low viscosity mineral oil base oil. Sufficient fuel economy can be demonstrated while maintaining the value.

  The lubricating oil composition of the present invention can also be suitably used for gasoline engines, diesel engines, gas engines, etc. for motorcycles, automobiles, power generation, cogeneration, etc. Not only can it be suitably used for these various engines using fuel of mass ppm or less, but it is also useful for various engines for ships and outboard motors.

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

In the lubricating oil composition according to the present embodiment, the lubricating oil base oil having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s and the spectrum obtained by (A) ¹³ C-NMR, the total area of all peaks A viscosity index improver in which the ratio M1 / M2 of the peak total area M1 between chemical shifts 36-38 ppm and the peak total area M2 between chemical shifts 64-66 ppm is 0.20 or more; and (B) friction adjustment And (C) an overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate.

In the lubricating oil composition according to the present embodiment, a lubricating base oil (hereinafter referred to as “the lubricating base oil according to the present embodiment”) having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s is used. .

As the lubricating base oil according to this embodiment, for example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and / or vacuum distillation is subjected to solvent removal, solvent extraction, hydrocracking, hydroisomerization. , Paraffinic mineral oil or normal paraffinic base oil refined by combining one or more kinds of purification processes such as solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay treatment, etc. Among isoparaffin base oils, those having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s can be mentioned.

As a preferable example of the lubricating base oil according to the present embodiment, the following base oils (1) to (8) are used as raw materials, and the raw oil and / or the lubricating oil fraction recovered from the raw oil is The base oil obtained by refine | purifying with a predetermined 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 (slack wax, etc.) obtained by the lubricant dewaxing process and / or synthetic wax (Fischer-Tropsch wax, GTL wax, etc.) obtained by the gas-to-liquid (GTL) process, etc.
(4) One or two or more mixed oils selected from base oils (1) to (3) and / or mild hydrocracked 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 refining; chemical (acid or alkali) cleaning such as sulfuric acid cleaning and caustic soda cleaning are preferred. 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 embodiment, a base oil selected from the above base oils (1) to (8) or a lubricating oil fraction recovered from the base oil is obtained by performing a predetermined treatment. The following base oil (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 a dewaxing process such as or by distillation after the dewaxing process.

  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 at an advantageous step.

  The catalyst used for the hydrocracking / hydroisomerization is not particularly limited, but a composite oxide having cracking activity (for example, silica alumina, alumina boria, silica zirconia, etc.) or one kind of the composite oxide. Hydrogenolysis with a combination of the above combined with a binder and supporting a metal having hydrogenation ability (for example, one or more metals such as Group VIa metal or Group VIII metal in the periodic table) Hydroisomerization catalyst in which a catalyst or a support containing zeolite (for example, ZSM-5, zeolite beta, SAPO-11, etc.) is loaded with a metal having a hydrogenation ability containing at least one of Group VIII metals Are preferably used. The hydrocracking catalyst and the hydroisomerization catalyst may be used in combination by stacking or mixing.

  The reaction conditions in the hydrocracking / hydroisomerization are not particularly limited, but the hydrogen partial pressure is 0.1 to 20 MPa, the average reaction temperature is 150 to 450 ° C., the LHSV is 0.1 to 3.0 hr-1, and the hydrogen / oil ratio. It is preferable to set it as 50-20000 scf / b.

The kinematic viscosity at 100 ° C. of the lubricating base oil according to this embodiment needs to be 20 mm ² / s or less, preferably 10 mm ² / s or less, more preferably 7 mm ² / s or less, and still more preferably. It is 5.0 mm ² / s or less, particularly preferably 4.5 mm ² / s or less, and most preferably 4.0 mm ² / s or less. On the other hand, the kinematic viscosity at 100 ° C. needs to be 1 mm ² / s or more, preferably 1.5 mm ² / s or more, more preferably 2 mm ² / s or more, and still more preferably 2. It is 5 mm ² / s or more, particularly preferably 3 mm ² / s or more. The kinematic viscosity at 100 ° C. referred to in the present invention indicates the kinematic viscosity at 100 ° C. defined in ASTM D-445. When the kinematic viscosity at 100 ° C. of the lubricating base oil exceeds 20 mm 2 / ^s, the worse the low temperature viscosity characteristics, also there is a risk that can not be obtained sufficient fuel saving properties, the following cases 1 mm 2 / ^s Since the formation of an oil film at the lubrication site is insufficient, the lubricity is inferior, and the evaporation loss of the lubricating oil composition may increase.

In the present invention, it is preferable to use a lubricating base oil having a kinematic viscosity at 100 ° C. in the following range by distillation or the like.
(I) less than the kinematic viscosity at 100 ° C. is 1.5 mm ² / s or more 3.5 mm ² / s, more preferably kinematic viscosity at 2.0 to 3.0 mm ² / s lubricating base oils (II) 100 ° C. There 3.5 mm ² / s or more 4.5mm less than ² / s, more preferably a kinematic viscosity in the lubricating base oil of ^{3.7~4.3mm 2 / s (III) 100} ℃ 4.5~10mm 2 / s, more preferably from 4.8 to 9 mm ² / s, particularly preferably from 5.5 to 8.0 mm ² / s.

The kinematic viscosity at 40 ° C. of the lubricating base oil according to the present embodiment is preferably 80 mm ² / s or less, more preferably 50 mm ² / s or less, still more preferably 20 mm ² / s or less, and particularly preferably 18 mm ^2. / S or less, most preferably 16 mm ² / s or less. On the other hand, the 40 ° C. kinematic viscosity is preferably 6.0 mm ² / s or more, more preferably 8.0 mm ² / s or more, further preferably 12 mm ² / s or more, particularly preferably 14 mm ² / s or more, and most preferably. Is 15 mm ² / s or more. If the 40 ° C. kinematic viscosity of the lubricating base oil exceeds 80 mm 2 / ^s, the low temperature viscosity characteristics are deteriorated, and there may not be obtained sufficient fuel savings, if: 6.0 mm 2 / ^s Is inferior in lubricity due to insufficient oil film formation at the lubrication site, and the evaporation loss of the lubricating oil composition may increase. Moreover, in this invention, it is preferable to fractionate and use the lubricating oil fraction whose kinematic viscosity in 40 degreeC is in the following range by distillation.
(IV) less than the kinematic viscosity at 40 ° C. is 6.0 mm ² / s or more 12 mm ² / s, more preferably 8.0~12mm ² / s lubricating base oil (V) kinematic viscosity at 40 ° C. is 12 mm ² / More than s and less than 28 mm < ² > / s, more preferably 13-19 mm < ² > / s lubricating base oil (VI) The kinematic viscosity at 40 [deg.] C. is 28-50 mm < ² > / s, more preferably 29-45 mm < ² > / s, particularly preferred. Is a lubricating base oil of 30 to 40 mm ² / s.

  The viscosity index of the lubricating base oil according to this embodiment is preferably 120 or more. Moreover, the viscosity index of the lubricating base oils (I) and (IV) is preferably 120 to 135, more preferably 120 to 130. The viscosity index of the lubricating base oils (II) and (V) is preferably 120 to 160, more preferably 125 to 150, and still more preferably 135 to 145. Further, the viscosity index of the lubricating base oils (III) and (VI) is preferably 120 to 180, more preferably 125 to 160. If the viscosity index is less than the lower limit, not only the viscosity-temperature characteristics, thermal / oxidative stability and volatilization prevention properties deteriorate, but also the friction coefficient tends to increase and the wear prevention properties tend to decrease. It is in. On the other hand, when the viscosity index exceeds the upper limit, the low-temperature viscosity characteristics tend to decrease.

  In addition, the viscosity index as used in the field of this invention means the viscosity index measured based on JISK2283-1993.

Further, the density (ρ ₁₅ ) at 15 ° C. of the lubricating base oil according to the present embodiment depends on the viscosity grade of the lubricating base oil, but is not more than the value of ρ represented by the following formula (A), that is, It is preferable that ρ ₁₅ ≦ ρ.
ρ = 0.0025 × kv100 + 0.816 (A)
[Wherein, kv100 represents the kinematic viscosity (mm ² / s) of the lubricating base oil at 100 ° C. ]

When ρ ₁₅ > ρ, the viscosity-temperature characteristics and thermal / oxidation stability, as well as volatilization prevention and low-temperature viscosity characteristics tend to decrease, which may deteriorate fuel economy. Moreover, when an additive is mix | blended with lubricating base oil, there exists a possibility that the effectiveness of the said additive may fall.

Specifically, the density (ρ ₁₅ ) at 15 ° C. of the lubricating base oil according to this embodiment is preferably 0.860 or less, more preferably 0.850 or less, still more preferably 0.840 or less, and particularly preferably. Is 0.822 or less.

  In addition, the density in 15 degreeC said by this invention means the density measured in 15 degreeC based on JISK2249-1995.

  Further, the pour point of the lubricating base oil according to the present embodiment depends on the viscosity grade of the lubricating base oil, but for example, the pour point of the lubricating base oils (I) and (IV) is preferably − It is 10 ° C or lower, more preferably -12.5 ° C or lower, and further preferably -15 ° C or lower. The pour points of the lubricating base oils (II) and (V) are preferably −10 ° C. or lower, more preferably −15 ° C. or lower, and still more preferably −17.5 ° C. or lower. The pour point of the lubricating base oils (III) and (VI) is preferably −10 ° C. or lower, more preferably −12.5 ° C. or lower, and further preferably −15 ° C. or lower. When the pour point exceeds the upper limit, the low temperature fluidity of the entire lubricating oil using the lubricating base oil tends to decrease. In addition, the pour point as used in the field of this invention means the pour point measured based on JISK2269-1987.

The aniline point (AP (° C.)) of the lubricating base oil of the present invention depends on the viscosity grade of the lubricating base oil, but is not less than the value of A represented by the following formula (B), that is, AP ≧ A is preferred.
A = 4.3 × kv100 + 100 (B)
[Wherein, kv100 represents the kinematic viscosity (mm ² / s) of the lubricating base oil at 100 ° C. ]

  When AP <A, viscosity-temperature characteristics and thermal / oxidative stability, volatilization prevention properties and low-temperature viscosity characteristics tend to decrease, and when additives are added to the lubricating base oil In addition, the effectiveness of the additive tends to decrease.

  For example, the AP of the lubricating base oils (I) and (IV) is preferably 108 ° C. or higher, more preferably 110 ° C. or higher. The AP of the lubricating base oils (II) and (V) is preferably 113 ° C. or higher, more preferably 119 ° C. or higher. The AP of the lubricating base oils (III) and (VI) is preferably 125 ° C. or higher, more preferably 128 ° C. or higher. In addition, the aniline point as used in the field of this invention means the aniline point measured based on JISK2256-1985.

  The iodine value of the lubricating base oil according to this embodiment is preferably 3 or less, more preferably 2 or less, still more preferably 1 or less, particularly preferably 0.9 or less, and most preferably 0. 8 or less. Further, it may be less than 0.01, but from the viewpoint of small effect corresponding to it and economic efficiency, it is preferably 0.001 or more, more preferably 0.01 or more, and further preferably 0.03. Above, especially preferably 0.05 or more. By setting the iodine value of the lubricating base oil component to 3 or less, the thermal and oxidation stability can be dramatically improved. In addition, the iodine value as used in the field of this invention means the iodine value measured by the indicator titration method of JISK0070 "the acid value of a chemical product, the saponification value, the iodine value, the hydroxyl value, and the unsaponification value."

  Further, the sulfur content in the lubricating base oil according to this embodiment depends on the sulfur content of the raw material. For example, when a raw material that does not substantially contain sulfur such as a synthetic wax component obtained by a Fischer-Tropsch reaction or the like is used, a lubricating base oil that does not substantially contain sulfur can be obtained. In addition, when using raw materials containing sulfur such as slack wax obtained in the refining process of the lubricating base oil and microwax obtained in the refining process, the sulfur content in the obtained lubricating base oil is usually 100 mass ppm. That's it. In the lubricating base oil according to the present embodiment, the content of sulfur is preferably 100 ppm by mass or less, and 50 ppm by mass or less, from the viewpoint of further improvement in thermal and oxidation stability and low sulfur content. More preferably, it is more preferably 10 ppm by mass or less, and particularly preferably 5 ppm by mass or less.

  Further, the nitrogen content in the lubricating base oil according to this embodiment is preferably 7 mass ppm or less, more preferably 5 mass ppm or less, and even more preferably 3 mass ppm or less. If the nitrogen content exceeds 5 ppm by mass, the thermal and oxidation stability tends to decrease. In addition, the nitrogen content as used in the field of this invention means the nitrogen content measured based on JISK2609-1990.

Moreover,% _{C p} value of the lubricating base oil of the present embodiment is preferably 70 or more, preferably 80 to 99, more preferably 85 to 95, more preferably 87-94, particularly preferably 90 to 94. When% C _p of the lubricating base oil is less than the above lower limit, viscosity-temperature characteristics, thermal / oxidative stability, and friction characteristics tend to decrease, and further, when additives are blended in the lubricating base oil In addition, the effectiveness of the additive tends to decrease. Further, when the% C _p value of the lubricating base oil exceeds the upper limit value, the additive solubility will tend to be lower.

Moreover,% C _A of the lubricating base oil of the present embodiment is preferably 2 or less, more preferably 1 or less, more preferably 0.8 or less, particularly preferably 0.5 or less. When% C _A of the lubricating base oil exceeds the upper limit value, the viscosity - temperature characteristic, thermal and oxidation stability and fuel efficiency tends to decrease.

Moreover,% _{C N} of the lubricating base oil of the present embodiment is preferably 30 or less, more preferably 4 to 25, more preferably 5 to 13, particularly preferably from 5 to 8. If the% C _N value of the lubricating base oil exceeds the upper limit value, the viscosity - temperature characteristic, thermal and oxidation stability and frictional properties will tend to be reduced. Moreover, when% _CN is less than the said lower limit, it exists in the tendency for the solubility of an additive to fall.

Incidentally, _say% C P in the present invention,% _C A _N and% _{C A,} obtained by a method in accordance with ASTM D 3238-85, respectively (n-d-M ring analysis), the total carbon number of the paraffin carbon number The percentage of the total number of naphthene carbons to the total number of carbons, and the percentage of aromatic carbons to the total number of carbons. In other words, the preferred ranges of% C _P ,% C _N and% C _A described above are based on the values obtained by the above method. For example, even for a lubricating base oil containing no naphthene, it can be obtained by the above method. is% C _N may indicate a value greater than zero.

  Further, the content of the saturated component in the lubricating base oil according to this embodiment is preferably 90% by mass or more, preferably 95% by mass or more, more preferably 99% by mass, based on the total amount of the lubricating oil base oil. In addition, the ratio of the cyclic saturated component in the saturated component is preferably 40% by mass or less, preferably 35% by mass or less, preferably 30% by mass or less, and more preferably 25% by mass. % Or less, and more preferably 21% by mass or less. Moreover, the ratio of the cyclic | annular saturated part which occupies for the said saturated part becomes like this. Preferably it is 5 mass% or more, More preferably, it is 10 mass% or more. When the content of the saturated component and the ratio of the cyclic saturated component in the saturated component satisfy the above conditions, the viscosity-temperature characteristics and the thermal / oxidative stability can be improved. When the additive is blended, the function of the additive can be expressed at a higher level while the additive is sufficiently stably dissolved and held in the lubricating base oil. Furthermore, according to the present invention, it is possible to improve the friction characteristics of the lubricating base oil itself, and as a result, it is possible to achieve an improvement in the friction reduction effect and an improvement in energy saving.

  The saturated content in the present invention is measured by the method described in the ASTM D 2007-93.

In addition, a similar method that can obtain the same result can be used in the separation method of the saturated component or the composition analysis of the cyclic saturated component and the non-cyclic saturated component. For example, in addition to the above, ASTM
Examples thereof include a method described in D 2425-93, a method described in ASTM D 2549-91, a method by high performance liquid chromatography (HPLC), a method obtained by improving these methods, and the like.

  The aromatic content in the lubricating base oil according to the present embodiment is preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, based on the total amount of the lubricating base oil. Preferably it is 2 mass% or less, Preferably it is 0.1 mass% or more, More preferably, it is 0.5 mass% or more, More preferably, it is 1 mass% or more, Most preferably, it is 1.5 mass% or more. If the aromatic content exceeds the above upper limit, the viscosity-temperature characteristics, thermal / oxidative stability, friction characteristics, volatilization prevention properties, and low-temperature viscosity characteristics tend to decrease. When an additive is blended with the additive, the effectiveness of the additive tends to decrease. Further, the lubricating base oil according to the present embodiment may not contain an aromatic component, but the solubility of the additive is further increased by setting the aromatic content to be equal to or higher than the above lower limit value. be able to.

  In addition, the aromatic component as used in the field of this invention means the value measured based on ASTM D 2007-93. In general, the aromatic component includes alkylbenzene, alkylnaphthalene, anthracene, phenanthrene and alkylated products thereof, as well as compounds in which four or more benzene rings are condensed, pyridines, quinolines, phenols and naphthols. Aromatic compounds having atoms are included.

A synthetic base oil may be used as the lubricating base oil according to this embodiment. Synthetic base oils include poly α-olefins or hydrides thereof, isobutene oligomers or hydrides thereof, isoparaffins, alkylbenzenes, alkylnaphthalenes, diesters (ditridecylglutarate) having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s. Rate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, etc.), polyol ester (trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, Pentaerythritol pelargonate), polyoxyalkylene glycols, dialkyl diphenyl ethers, polyphenyl ethers, etc., among which poly α-olefins are preferred. Arbitrariness. As the poly α-olefin, typically, an α-olefin oligomer or co-oligomer having 1 to 32 carbon atoms, preferably 6 to 16 (1-octene oligomer, decene oligomer, ethylene-propylene co-oligomer, etc.) and the like. Of the hydrides.

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

  In the lubricating oil composition according to the present embodiment, the lubricating base oil according to the present embodiment may be used alone, and the lubricating base oil according to the present embodiment may be one of other base oils or You may use together with 2 or more types. In addition, when using together the lubricating base oil which concerns on this embodiment, and another base oil, the ratio of the lubricating base oil which concerns on this embodiment in those mixed base oils is 30 mass% or more Is more preferable, it is more preferable that it is 50 mass% or more, and it is still more preferable that it is 70 mass% or more.

Other base oil used in combination with the lubricating base oil of the present embodiment is not particularly limited, examples of mineral base oils, for example, a kinematic viscosity at 100 ° C. is 20 mm 2 / ^s, greater 200 mm 2 / ^s or less Solvent refined mineral oil, hydrocracked mineral oil, hydrorefined mineral oil, solvent dewaxing base oil, and the like.

Moreover, as another synthetic base oil used together with the lubricating base oil according to this embodiment, the above-described synthetic base oil whose kinematic viscosity at 100 ° C. is outside the range of 1 to ²⁰ mm ² / s can be mentioned. It is done.

The (A) viscosity index improver used in the present invention is a spectrum obtained by nuclear magnetic resonance analysis ( ¹³ C-NMR). The total area of peaks (M1) between chemical shifts of 36 to 38 ppm relative to the total area of all peaks. ) And the chemical shift of 64-66 ppm, the ratio of the peak total area (M2), that is, M1 / M2 is 0.20 or more.

  The (A) viscosity index improver that satisfies the above conditions is specifically a non-dispersed or dispersed ester group-containing viscosity index improver, for example, a non-dispersed or dispersed poly (meth) acrylate viscosity index. Examples include improvers, non-dispersed or dispersed olefin- (meth) acrylate copolymer viscosity index improvers, styrene-maleic anhydride copolymer viscosity index improvers, and mixtures thereof. Among these, non-dispersed It is preferably a mold-type or dispersion-type poly (meth) acrylate viscosity index improver. A non-dispersed or dispersed polymethacrylate viscosity index improver is particularly preferable.

  M1 / M2 is preferably 0.3 or more, more preferably 0.4 or more, particularly preferably 0.5 or more, and most preferably 0.6 or more. M1 / M2 is preferably 3.0 or less, more preferably 2.0 or less, particularly preferably 1.0 or less, and most preferably 0.8 or less. When M1 / M2 is less than 0.20, not only the required fuel-saving property cannot be obtained, but also the low-temperature viscosity characteristics may be deteriorated. Moreover, when M1 / M2 exceeds 3.0, there exists a possibility that the required fuel-saving property may not be acquired, and there exists a possibility that solubility and storage stability may deteriorate.

In addition, a nuclear magnetic resonance analysis ( ^13C -NMR) spectrum is obtained about the polymer which isolate | separated dilution oil by rubber membrane dialysis etc., when a dilution oil is contained in a viscosity index improver.

The total area of the peak (M1) between chemical shifts 36-38 ppm relative to the total area of all peaks is the integral of total carbon as measured by ¹³ C-NMR when the viscosity index improver is poly (meth) acrylate, for example. The ratio of the integrated intensity derived from a specific β-branched structure of the poly (meth) acrylate side chain to the total intensity, and the total area (M2) of the peak between chemical shifts 64-66 ppm relative to the total area of all peaks is , Which means the ratio of the integrated intensity derived from the specific linear structure of the poly (meth) acrylate side chain to the total integrated intensity of all carbons as measured by ¹³ C-NMR.

M1 / M2 means the ratio of the specific β-branched structure of the poly (meth) acrylate side chain and the specific linear structure, but other methods may be used as long as equivalent results are obtained. In the ¹³ C-NMR measurement, a sample diluted with 0.5 g of a sample added with 3 g of deuterated chloroform was used, the measurement temperature was room temperature, the resonance frequency was 125 MHz, and the measurement method was a gated decoupling method. It was used.

From the above analysis,
(A) Sum of integral intensities with chemical shifts of about 10-70 ppm (sum of integral intensities due to total carbon of hydrocarbons), and (b) Sum of integral intensities with chemical shifts of 36-38 ppm (for specific β-branch structures) Sum of integral intensities due to), and (c) sum of integral intensities with chemical shifts of 64-66 ppm (sum of integral intensities due to specific linear structures)
Were measured, and the ratio (%) of (b) when (a) was set to 100% was calculated as M1. Further, the ratio (%) of (c) when (a) was set to 100% was calculated as M2.

［上記一般式（１）中、Ｒ^１は水素又はメチル基を示し、Ｒ^２は炭素数１〜２００の直鎖状又は分枝状の炭化水素基を示す。］ The poly (meth) acrylate viscosity index improver that can be used in the present embodiment (the poly (meth) acrylate system in the present invention is a general term for polyacrylate compounds and polymethacrylate compounds) is preferably as follows. It is a polymer of a polymerizable monomer containing a (meth) acrylate monomer represented by the general formula (1) (hereinafter referred to as “monomer M-1”).

[In the general formula (1), R ¹ represents hydrogen or a methyl group, and R ² represents a linear or branched hydrocarbon group having 1 to 200 carbon atoms. ]

［一般式（２）中、Ｒ^３は水素原子又はメチル基を示し、Ｒ^４は炭素数１〜１８のアルキレン基を示し、Ｅ^１は窒素原子を１〜２個、酸素原子を０〜２個含有するアミン残基又は複素環残基を示し、ａは０又は１を示す。］

［一般式（３）中、Ｒ^５は水素原子又はメチル基を示し、Ｅ^２は窒素原子を１〜２個、酸素原子を０〜２個含有するアミン残基又は複素環残基を示す。］ The poly (meth) acrylate compound obtained by homopolymerization of two or more types of monomers represented by the general formula (1) is a so-called non-dispersed poly (meth) acrylate. The poly (meth) acrylate compound according to the embodiment includes a monomer represented by the general formula (1) and one or more monomers selected from the general formulas (2) and (3) (hereinafter referred to as “monomer M-2”, respectively). And a so-called dispersed poly (meth) acrylate obtained by copolymerization of “monomer M-3”.

[In General Formula (2), R ³ represents a hydrogen atom or a methyl group, R ⁴ represents an alkylene group having 1 to 18 carbon atoms, E ¹ represents ¹ to 2 nitrogen atoms, and 0 to 2 oxygen atoms. Each represents an amine residue or a heterocyclic residue, and a represents 0 or 1. ]

[In General Formula (3), R ⁵ represents a hydrogen atom or a methyl group, and 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.

  As preferable examples of the monomer M-2 and the monomer M-3, specifically, dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, morpholinomethyl methacrylate , Morpholinoethyl methacrylate, N-vinylpyrrolidone, and mixtures thereof.

  There is no particular limitation on the copolymerization molar ratio of the copolymer of the monomer M-1 and the monomers M-2 to M-3, but M-1: M-2 to M-3 = 99: 1 to 80:20. A degree is preferable, More preferably, it is 98: 2-85: 15, More preferably, it is 95: 5-90: 10.

  Although the production method of the poly (meth) acrylate is arbitrary, for example, in the presence of a polymerization initiator such as benzoyl peroxide, the monomer (M-1) and the monomers (M-2) to (M-3) It can be easily obtained by radical solution polymerization of the mixture.

  The (SI) viscosity index improver has a PSSI (Permanent Cystability Index) of preferably 40 or less, more preferably 35 or less, still more preferably 30 or less, and particularly preferably 25 or less. Moreover, it is preferable that it is 0.1 or more, More preferably, it is 0.5 or more, More preferably, it is 2 or more, Especially preferably, it is 5 or more. When PSSI is less than 0.1, the effect of improving the viscosity index is small and the cost may increase. When PSSI exceeds 40, shear stability and storage stability may be deteriorated.

(A) The weight average molecular weight of the viscosity index improver _{(M W)} is preferably at least 100,000, more preferably 200,000 or more, even more preferably 250,000 or more, particularly preferably 300 1,000 or more. Moreover, it is preferably 1,000,000 or less, more preferably 700,000 or less, further preferably 600,000 or less, and particularly preferably 500,000 or less. When the weight average molecular weight is less than 100,000, the effect of improving the viscosity temperature characteristics and the effect of improving the viscosity index may be small and the cost may increase. When the weight average molecular weight exceeds 1,000,000, the shear stability There is a risk that the solubility in water and base oil and the storage stability may deteriorate.

(A) The number average molecular weight (M _N ) of the viscosity index improver is preferably 50,000 or more, more preferably 800,000 or more, still more preferably 100,000 or more, and particularly preferably 120. 1,000 or more. Further, it is preferably 500,000 or less, more preferably 300,000 or less, further preferably 250,000 or less, and particularly preferably 200,000 or less. If the number average molecular weight is less than 50,000, the effect of improving the viscosity temperature characteristics and the effect of improving the viscosity index may be small and the cost may increase. If the weight average molecular weight exceeds 500,000, shear stability and There is a possibility that solubility in oil and storage stability may deteriorate.

(A) The ratio of the weight average molecular weight of the viscosity index improver to the PSSI (M _W / PSSI) is preferably 1.0 × 10 ⁴ or more, preferably 1.5 × 10 ⁴ or more, more preferably 2 0.0 × 10 ⁴ or more, more preferably 2.5 × 10 ⁴ or more, and particularly preferably 3.0 × 10 ⁴ or more. If M _W / PSSI is below 1.0 × 10 ^4, there is a possibility that the viscosity-temperature characteristic is deteriorated i.e. deteriorates fuel efficiency.

(A) The ratio of the weight average molecular weight to the number average molecular weight (M _W / M _N ) of the viscosity index improver is preferably 0.5 or more, preferably 1.0 or more, more preferably 1.5 or more. More preferably, it is 2.0 or more, and particularly preferably 2.1 or more. _Further, it is preferred that the M W / _{M N} is 6.0 or less, more preferably 4.0 or less, more preferably 3.5 or less, particularly preferably 3.0 or less. When _MW / _MN is less than 0.5 or exceeds 6.0, the viscosity temperature characteristic may be deteriorated, that is, the fuel economy may be deteriorated.

(A) The kinematic viscosity thickening ratio ΔKV40 / ΔKV100 at 40 ° C. and 100 ° C. of the viscosity index improver is preferably 4.0 or less, more preferably 3.5 or less, and even more preferably 3.0 or less. Particularly preferred is 2.5 or less, and most preferred is 2.3 or less. ΔKV40 / ΔKV100 is preferably 0.5 or more, more preferably 1.0 or more, still more preferably 1.5 or more, and particularly preferably 2.0 or more.
If ΔKV40 / ΔKV100 is less than 0.5, the effect of increasing viscosity and solubility may be small and the cost may increase. If it exceeds 4.0, the effect of improving viscosity temperature characteristics and low temperature viscosity characteristics may be obtained. May be inferior. ΔKV40 means an increase in kinematic viscosity at 40 ° C. when 3.0% of a viscosity index improver is added to SK YUBASE4, and ΔKV100 is 3.0% of SKBASE YUBASE4. It means an increase in kinematic viscosity at 100 ° C. when added in%.

(A) HTHS viscosity increase ratio ΔHTHS100 / ΔHTHS150 at 100 ° C. and 150 ° C. of the viscosity index improver is preferably 2.0 or less, more preferably 1.7 or less, and even more preferably 1.6 or less. Particularly preferably, it is 1.55 or less. ΔHTHS100 / ΔHTHS150 is preferably 0.5 or more, more preferably 1.0 or more, still more preferably 1.2 or more, and particularly preferably 1.4 or more.
If it is less than 0.5, the viscosity increasing effect and solubility may be small and the cost may increase, and if it exceeds 2.0, the viscosity temperature characteristic improving effect and the low temperature viscosity characteristic may be inferior. .
ΔHTHS100 means an increase in HTHS viscosity at 100 ° C. when 3.0% of a viscosity index improver is added to YUBASE4 manufactured by SK, and ΔHTHS150 is 3.0% of YUBASE4 manufactured by SK. It means an increase in HTHS viscosity at 150 ° C. when added in%. ΔHTHS100 / ΔHTHS150 means the ratio of the increase in HTHS viscosity at 100 ° C. to the increase in HTHS viscosity at 150 ° C. The HTHS viscosity at 100 ° C. referred to in the present invention indicates the high temperature and high shear viscosity at 100 ° C. as defined in ASTM D4683. Moreover, the HTHS viscosity at 150 ° C. indicates the high temperature and high shear viscosity at 150 ° C. defined in ASTM D4683.

  The content of the (A) viscosity index improver in the lubricating oil composition according to this embodiment is preferably 0.01 to 50% by mass, more preferably 0.5 to 40%, based on the total amount of the lubricating oil composition. % By mass, more preferably 1-30% by mass, particularly preferably 3-20% by mass, most preferably 5-10% by mass. (A) When the content of the viscosity index improver is less than 0.1% 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 50% 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. There is concern that it may cause defects such as seizure, seizure and fatigue failure.

  In the lubricating oil composition according to this embodiment, in addition to the component (A) described above, other viscosity index improvers can be used as the viscosity index improver. Examples include non-dispersed or dispersed ethylene-α-olefin copolymers or hydrogenated products thereof, polyisobutylene or hydrogenated products thereof, styrene-diene hydrogenated copolymers, and polyalkylstyrenes.

  The lubricating oil composition according to this embodiment contains (B) a friction modifier. Thereby, compared with the case where this structure is not provided, a fuel-saving performance can be improved. (B) As a friction modifier, 1 or more types of friction modifiers chosen from an organic molybdenum compound and an ashless friction modifier are mentioned.

  Examples of the organic molybdenum compound used in the present embodiment include sulfur-containing organic molybdenum compounds such as molybdenum dithiophosphate and molybdenum dithiocarbamate (MoDTC), molybdenum compounds (for example, molybdenum oxide such as molybdenum dioxide and molybdenum trioxide, and orthomolybdic acid. , Molybdate such as paramolybdic acid, (poly) sulfurized molybdate, metal salts of these molybdates, molybdate such as ammonium salt, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, molybdenum sulfide such as polysulfide molybdenum , Sulfurized molybdic acid, metal salts or amine salts of sulfurized molybdic acid, molybdenum halides such as molybdenum chloride, etc.) and sulfur-containing organic compounds (eg, alkyl (thio) xanthate, thiadiazole, mercaptothiadi) Sol, thiocarbonate, tetrahydrocarbyl thiuram disulfide, bis (di (thio) hydrocarbyl dithiophosphonate) disulfide, organic (poly) sulfide, sulfide ester, etc.) or other organic compounds, or the above sulfides A complex of a sulfur-containing molybdenum compound such as molybdenum or sulfurized molybdic acid and an alkenyl succinimide can be given.

  As the organic molybdenum compound, an organic molybdenum compound containing no sulfur as a constituent element can be used. Specific examples of organic molybdenum compounds that do not contain sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, and molybdenum salts of alcohols. Complexes, molybdenum salts of organic acids and molybdenum salts of alcohols are preferred.

  In the lubricating oil composition according to the present embodiment, when an organic molybdenum compound is used, its content is not particularly limited, but based on the total amount of the lubricating oil composition, preferably in terms of molybdenum element, preferably 0.001% by mass or more, More preferably 0.005% by mass or more, further preferably 0.01% by mass or more, particularly preferably 0.03% by mass or more, and preferably 0.2% by mass or less, more preferably 0.1% by mass. % Or less, more preferably 0.08 mass% or less, and particularly preferably 0.06 mass% or less. When the content is less than 0.001% by mass, the thermal and oxidation stability of the lubricating oil composition becomes insufficient, and in particular, it tends to be impossible to maintain excellent cleanliness over a long period of time. On the other hand, when the content exceeds 0.2% by mass, an effect commensurate with the content cannot be obtained, and the storage stability of the lubricating oil composition tends to decrease.

  Further, as the ashless friction modifier, any compound usually used as a friction modifier for lubricating oil can be used. For example, one or two selected from oxygen atom, nitrogen atom, sulfur atom in the molecule Examples thereof include compounds having 6 to 50 carbon atoms and containing at least a hetero element. More specifically, it has at least one alkyl group or alkenyl group having 6 to 30 carbon atoms, particularly a straight chain alkyl group, straight chain alkenyl group, branched alkyl group or branched alkenyl group having 6 to 30 carbon atoms in the molecule. Ashless friction modifiers such as amine compounds, fatty acid esters, fatty acid amides, fatty acids, fatty alcohols, aliphatic ethers, urea compounds, hydrazide compounds, and the like.

  The content of the ashless friction modifier in the lubricating oil composition according to this embodiment is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and still more preferably, based on the total amount of the lubricating oil composition. Is 0.3% by mass or more, preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less. When the content of the ashless friction modifier is less than 0.01% by mass, the effect of reducing friction due to the addition tends to be insufficient, and when the content exceeds 3% by mass, the effect of an antiwear additive or the like. Tends to be inhibited, or the solubility of the additive tends to deteriorate.

  In the present embodiment, the friction modifier (B) is preferably a molybdenum friction modifier, more preferably an organic molybdenum compound containing sulfur, and even more preferably molybdenum dithiocarbamate.

  In the lubricating oil composition according to this embodiment, (C) an overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate (hereinafter referred to as “(C) first overbased "Metal salt"). Thereby, compared with the case where this structure is not provided, a fuel-saving performance can be improved.

  (C) 1st overbased metal salt used by this embodiment is oil-soluble metal salts, such as oil-soluble alkaline-earth metal sulfonate, alkaline-earth metal salicylate, alkaline-earth metal phenate, alkaline-earth metal phosphonate And an alkaline earth metal hydroxide or oxide and boric acid or boric anhydride. Examples of alkaline earth metals include magnesium, calcium, barium and the like, with calcium being preferred. As the oil-soluble metal salt, alkaline earth metal salicylate is preferably used.

  (C) The base number of the first overbased metal salt is preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, further preferably 150 mgKOH / g or more, 200 or more. It is particularly preferred that Moreover, it is preferable that it is 500 mgKOH / g or less, It is more preferable that it is 400 mgKOH / g or less, It is especially preferable that it is 300 mgKOH / g or less. The base number in the present invention is a value measured according to JIS K 2501 5.2.3.

  In addition, the particle size of (C) the first overbased metal salt is preferably 0.1 μm or less, more preferably 0.05 μm or less.

  (C) Although the manufacturing method of the 1st overbased metal salt is arbitrary, for example, said oil-soluble metal salt, alkaline earth metal hydroxide or oxide, and boric acid or anhydrous boric acid are mixed with water, methanol. In the presence of alcohol such as ethanol, propanol and butanol and diluting solvents such as benzene, toluene and xylene, the reaction is carried out at 20 to 200 ° C. for 2 to 8 hours. It is obtained by removing alcohol and diluting solvent. These detailed reaction conditions are appropriately selected according to the raw materials, the amount of reactants, and the like. Details of the production method are described in, for example, JP-A-60-116688 and JP-A-61-204298. The particle size of the overbased metal salt obtained by overbasing the oil-soluble metal salt produced by the above method with an alkaline earth metal borate is usually 0.1 μm or less, and the total base number is usually 100 mgKOH / g or more. The lubricating oil composition according to this embodiment can be preferably used.

  The content of the (C) first overbased metal salt in the lubricating oil composition according to the present embodiment is preferably 0.01 to 30% by mass, more preferably 0.05, based on the total amount of the lubricating oil composition. ˜5 mass%. If the content is less than 0.01% by mass, the fuel saving effect may last only for a short period, and if it exceeds 30% by mass, the effect corresponding to the content may not be obtained. There is not preferable.

  In the lubricating oil composition according to this embodiment, in addition to (C) the first overbased metal salt, (E) an overbased metal obtained by overbasing an oil-soluble metal salt with an alkaline earth metal carbonate. More preferably, a salt (hereinafter referred to as “(E) second overbased metal salt”) is used in combination. (E) As the second overbased metal salt, an overbased alkaline earth metal sulfonate obtained by overbasing an alkaline earth metal sulfonate with an alkaline earth metal carbonate, or an alkaline earth metal phenate as an alkaline earth metal Examples include overbased alkaline earth metal phenates overbased with carbonates, overbased alkaline earth metal salicylates obtained by overbasing alkaline earth metal salicylates with alkaline earth metal carbonates, and the like. Examples of alkaline earth metals include magnesium, calcium, barium and the like, with calcium being preferred. Among these, it is particularly preferable to use together an overbased calcium salicylate obtained by overbasing an alkaline earth metal salicylate with an alkaline earth metal carbonate.

  In the lubricating oil composition according to this embodiment, when (C) the first overbased metal salt and (E) the second overbased metal salt are used in combination, (E) the second overbased metal salt The base number is preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, further preferably 150 mgKOH / g or more, and particularly preferably 200 mgKOH / g or more. Moreover, it is preferable that it is 500 mgKOH / g or less, It is more preferable that it is 400 mgKOH / g or less, It is especially preferable that it is 300 mgKOH / g or less.

  In order to further improve the performance, 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 other than the first and second overbased metal salts, ashless dispersants, antiwear agents (or extreme pressure agents), antioxidants, and corrosion inhibitors. And additives such as rust preventives, demulsifiers, metal deactivators and antifoaming agents.

  Examples of metal detergents other than the first and second overbased metal salts include alkali metal / alkaline earth metal sulfonate, alkali metal / alkaline earth metal phenate, and alkali metal / alkaline earth metal salicylate. Mention may be made of normal or 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.

  As the antiwear agent (or extreme pressure agent), any antiwear agent / extreme pressure agent used in lubricating oils can be used. For example, sulfur-based, phosphorus-based, sulfur-phosphorus extreme pressure agents and the like can be used. Specifically, zinc dialkyldithiophosphate (ZnDTP), phosphites, thiophosphites, dithiophosphites Acid esters, trithiophosphites, phosphate esters, thiophosphate esters, dithiophosphate esters, trithiophosphate esters, amine salts thereof, metal salts thereof, derivatives thereof, dithiocarbamate, zinc dithio Carbamate, MoDTC, disulfides, polysulfides, sulfurized olefins, sulfurized fats and oils, and the like can be given. Among these, addition of a sulfur-based extreme pressure agent is preferable, and sulfurized fats and oils are particularly preferable.

  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, thiadiazole, or imidazole compounds.

  Examples of the rust inhibitor include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, 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 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 according to the present embodiment, each content is preferably 0.01 to 10% by mass based on the total amount of the lubricating oil composition.

Kinematic viscosity at 100 ° C. of the lubricating oil composition according to the present embodiment is preferably 4 to 12 mm ² / s, preferably not more than ^{9 mm} 2 / s, more preferably ^{8 mm} 2 / s or less, more preferably 7 .8mm ² / s or less, particularly preferably not more than 7.6 mm ² / s. Further, the kinematic viscosity at 100 ° C. of the lubricating oil composition according to this embodiment is preferably 5 mm ² / s or more, more preferably 6 mm ² / s or more, still more preferably 6.5 mm ² / s or more, particularly preferably. 7 mm ² / s or more. The kinematic viscosity at 100 ° C. referred to in the present invention indicates the kinematic viscosity at 100 ° C. 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 12 mm ² / s, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained. is there.

The kinematic viscosity at 40 ° C. of the lubricating oil composition according to this embodiment is preferably 4 to 50 mm ² / s, preferably 40 mm ² / s or less, more preferably 35 mm ² / s or less, and particularly preferably 32 mm. ² / s or less, most preferably 30 mm ² / s or less. The kinematic viscosity at 40 ° C. of the lubricating oil composition according to the present embodiment is preferably 10 mm ² / s or more, more preferably 20 mm ² / s or more, further preferably 25 mm ² / s or more, and particularly preferably 27 mm ^2. / S or more. The kinematic viscosity at 40 ° C. referred to in the present invention indicates the kinematic viscosity at 40 ° C. defined in ASTM D-445. If the kinematic viscosity at 40 ° C. is less than 4 mm ² / s, there is a risk of insufficient lubricity, and if it exceeds 50 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 according to this embodiment is preferably in the range of 140 to 400, preferably 190 or more, more preferably 200 or more, still more preferably 210 or more, and particularly preferably 220 or more. When the viscosity index of the lubricating oil composition according to the present embodiment is less than 140, it may be difficult to improve fuel economy while maintaining the HTHS viscosity of 150 ° C., and further at −35 ° C. It may be difficult to reduce the low temperature viscosity. In addition, when the viscosity index of the lubricating oil composition according to the present embodiment is 400 or more, there is a possibility that the evaporability may be deteriorated, and further, a problem due to insufficient solubility of the additive and compatibility with the sealing material. May occur.

  The HTHS viscosity at 100 ° C. of the lubricating oil composition according to this embodiment is preferably 5.5 mPa · s or less, more preferably 5.0 mPa · s or less, even more preferably 4.8 mPa · s or less, particularly Preferably, it is 4.7 mPa · s or less. Further, it is preferably 3.0 mPa · s or more, more preferably 3.5 mPa · s or more, particularly preferably 4.0 mPa · s or more, and most preferably 4.2 mPa · s or more. The HTHS viscosity at 100 ° C. referred to in the present invention indicates the high temperature and high shear viscosity at 100 ° C. as defined in ASTM D4683. When the HTHS viscosity at 100 ° C. is less than 3.0 mPa · s, there is a risk of insufficient lubricity, and when it exceeds 5.5 mPa · s, the necessary low temperature viscosity and sufficient fuel saving performance cannot be obtained. There is a fear.

  The HTHS viscosity at 150 ° C. of the lubricating oil composition according to this embodiment is preferably 3.5 mPa · s or less, more preferably 3.0 mPa · s or less, even more preferably 2.8 mPa · s or less, particularly The pressure is preferably 2.7 mPa · s or less. Further, it is preferably 2.0 mPa · s or more, more preferably 2.3 mPa · s or more, further preferably 2.4 mPa · s or more, particularly preferably 2.5 mPa · s or more, and most preferably 2.6 mPa · s or more. It is. The HTHS viscosity at 150 ° C. referred to in the present invention indicates the high temperature and high shear viscosity at 150 ° C. defined in ASTM D4683. When the HTHS viscosity at 150 ° C. is less than 2.0 mPa · s, there is a risk of insufficient lubricity, and when it exceeds 3.5 mPa · s, the necessary low temperature viscosity and sufficient fuel saving performance cannot be obtained. There is a fear.

  In addition, the ratio of the HTHS viscosity at 150 ° C. to the HTHS viscosity at 100 ° C. (HTHS viscosity at 150 ° C./HTHS viscosity at 100 ° C.) of the lubricating oil composition according to the present embodiment is preferably 0.50 or more. More preferably, it is 0.52 or more, More preferably, it is 0.54, Especially preferably, it is 0.55 or more, Most preferably, it is 0.56 or more. If the ratio is less than 0.50, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained.

  The lubricating oil composition according to the present embodiment is excellent in fuel economy and lubricity, and it is 150 without using a synthetic oil such as a poly-α-olefin base oil or an ester base oil or a low-viscosity mineral oil base oil. The kinematic viscosity at 40 ° C. and 100 ° C. and the HTHS viscosity at 100 ° C. of the lubricating oil, which are effective for improving fuel efficiency, while maintaining the HTHS viscosity at 0 ° C. at a constant level, are remarkably reduced. The lubricating oil composition according to this embodiment having such excellent characteristics can be suitably used as a fuel-saving engine oil such as a fuel-saving gasoline engine oil and a fuel-saving diesel engine oil.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Examples 1-5, Comparative Examples 1-3]
In Examples 1 to 5 and Comparative Examples 1 to 3, lubricating oil compositions having the compositions shown in Table 2 were prepared using the base oils and additives shown below, respectively. Table 1 shows the properties of the base oils O-1, O-2, and O-3.
(Base oil)
O-1 (Base oil 1): Mineral oil obtained by hydrocracking / hydroisomerizing n-paraffin-containing oil O-2 (Base oil 2): Mineral oil obtained by hydrocracking / hydroisomerizing n-paraffin-containing oil O-3 (Base oil 3): Hydrocracked mineral oil (additive)
A-1: Polymethacrylate (M1 = 1.45, M2 = 3.99, M1 / M2 = 0.48, ΔKV40 / ΔKV100 = 1.9, ΔHTHS100 / ΔHTHS150 = 1.48, MW = 400,000, PSSI = 12, Mw / Mn = 3.1, Mw / PSSI = 33,333)
A-2: Polymethacrylate (M1 = 0.60, M2 = 0.95, M1 / M2 = 0.64, ΔKV40 / ΔKV100 = 2.2, ΔHTHS100 / ΔHTHS150 = 1.51, MW = 400,000, PSSI = 20, Mw / Mn = 2.2, Mw / PSSI = 20,000)
a-1: Dispersed polymethacrylate (M1 = 0.46, M2 = 3.52, M1 / M2 = 0.13, ΔKV40 / ΔKV100 = 3.3, ΔHTHS100 / ΔHTHS150 = 1.79, MW = 300,000 PSSI = 40, Mw / Mn = 4.0, Mw / PSSI = 7500)
B-1: MoDTC (Mo content 10% by mass)
C-1: Overbased calcium borate salicylate obtained by overbasing calcium salicylate with calcium borate (base number 190 mgKOH / g, Ca content 6.8% by mass, B content 2.7% by mass)
c-1: Overbased calcium salicylate (base number 170 mg KOH / g, Ca content 6.3%)
d-1: Succinimide dispersant (Mw13000)
e-1: ZnDTP (sec-type, P content 6.2 mass%)
f-1: Other additives (antioxidants, antiwear agents, pour point depressants, antifoaming agents, etc.).

[Evaluation of lubricating oil composition]
About each lubricating oil composition of Examples 1-5 and Comparative Examples 1-3, kinematic viscosity in 40 degreeC or 100 degreeC, a viscosity index, and HTHS viscosity in 100 degreeC or 150 degreeC were measured. The fuel efficiency was measured by measuring engine friction. Each physical property value and fuel economy were measured by the following evaluation methods. The obtained results are shown in Table 2.
(1) Kinematic viscosity: ASTM D-445
(2) Viscosity index: JIS K 2283-1993
(3) HTHS viscosity: ASTM D-4683
(4) Engine friction test: using a 2L engine, calculating an average value of friction at each measurement point of an oil temperature of 60 ° C. to 100 ° C. and a rotation speed of 500 to 1500 rpm, and using Comparative Example 1 as a reference oil The improvement rate was calculated.

As shown in Table 2, lubricating oil compositions of Examples 1 to 5 using polymethacrylate having a specific structure and adding an overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate The thing shows that the motoring friction improvement rate (friction reduction rate) is large, and is excellent in fuel efficiency. In contrast, the lubricating oil composition of Comparative Example 1 that does not contain an overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate has the same HTHS viscosity at 150 ° C. Despite being, motoring friction is large (improvement rate is small). The lubricating oil composition of Comparative Example 2 which does not contain an overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate and does not contain the predetermined polymethacrylate of the present application is also motoring friction. Is large (improvement rate is small). The lubricating oil composition of Comparative Example 3 containing no friction modifier also has high motoring friction (small improvement rate). The lubricating oil composition of the present invention maintains a high temperature and high shear viscosity at 150 ° C. without using a synthetic oil such as a poly-α-olefin base oil or an ester base oil or a low viscosity mineral oil base oil. In addition to the ability to reduce the 100 ° C. HTHS viscosity, it can be seen that the addition of a friction modifier and a specific metal detergent significantly improves fuel economy.

Claims (5)

A lubricating base oil having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s;
^{In the} spectrum obtained by ¹³ C-NMR, the ratio M1 / M2 of the peak total area M1 between the chemical shift 36-38 ppm and the peak total area M2 between the chemical shift 64-66 ppm relative to the total area of all peaks is 0. A viscosity index improver that is 20 or greater;
A friction modifier;
An overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate;
A lubricating oil composition comprising:   The lubricating oil composition according to claim 1, wherein the viscosity index improver is a poly (meth) acrylate viscosity index improver. 3. The lubricating oil composition according to claim 1, wherein the viscosity index improver has a PSSI of 40 or less and a ratio of a weight average molecular weight to PSSI of 1 × 10 ⁴ or more.   The lubricating oil composition according to any one of claims 1 to 3, wherein the friction modifier is an organic molybdenum compound.   The overbased metal salt obtained by overbasing the oil-soluble metal salt with an alkaline earth metal borate is an alkaline earth metal salicylate overbased with an alkaline earth metal borate. The lubricating oil composition according to any one of claims 1 to 4.