JP2010280825A - Lubricant composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant composition which has a satisfactorily high viscosity index and is excellent in fuel saving properties and lubricity. <P>SOLUTION: The lubricant composition contains: a lubricant base oil having 1-20 mm<SP>2</SP>/s kinetic viscosity at 100°C; an ester compound; and a viscosity index improver having ≥0.20 ratio M1/M2 (wherein M1 is the total area of peaks between 36-38 ppm chemical shift relative to the total area of all peaks relative to the total area of all peaks; M2 is the total area of peaks between 64-66 ppm chemical shift relative to the total area of all peaks) in a spectrum obtained by<SP>13</SP>C-NMR. <P>COPYRIGHT: (C)2011,JPO&INPIT

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 base oils and viscosity index improvers are not necessarily sufficient in terms of fuel economy and low temperature viscosity characteristics.

  As a general method for reducing fuel consumption, there are known a method for reducing the kinematic viscosity of a product and a multi-gradation by combining a viscosity index improvement, that is, a base oil viscosity reduction and a viscosity index improver. However, there is a concern that the reduction in product viscosity and the reduction in base oil viscosity will reduce the lubrication performance under severe lubrication conditions such as high-temperature and high-shear conditions and cause problems such as wear, seizure, and fatigue failure. .

  Therefore, in order to prevent these problems and maintain durability, it is necessary to reduce the viscosity in the normal temperature range while maintaining the viscosity at a high temperature. That is, it is important to improve the viscosity index in order to provide further fuel saving while maintaining other practical performance.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lubricating oil composition having a sufficiently high viscosity index and excellent fuel economy and lubricity.

In order to solve the above problems, the present invention provides a lubricating oil base oil having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s, an ester compound, and a total of all peaks in a spectrum obtained by ¹³ C-NMR. A viscosity index improver having a ratio M1 / M2 of a total area M1 of peaks between 36-38 ppm of chemical shift to area and a total area M2 of peaks between 64-66 ppm of chemical shift of 0.20 or more. A lubricating oil composition is provided.

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

Further, the 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 (Permanent Shear) calculated based on data measured by the European Diesel Injector Apparatus
Means Stability Index).

  The lubricating oil composition of the present invention preferably further contains at least one friction modifier selected from organic molybdenum compounds and ashless friction modifiers.

  According to the present invention, it is possible to provide a lubricating oil composition having a sufficiently high viscosity index and excellent fuel economy and lubricity.

  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 of the present invention, kinematic viscosity at 100 ° C. is 1 to 20 mm 2 / ^s (A) the lubricating base oil (hereinafter, referred to as "lubricating base oil of the present invention".) Are used .

The lubricating base oil according to the present invention is not particularly limited as long as the kinematic viscosity at 100 ° C. satisfies the above conditions. Specifically, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and / or vacuum distillation is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid Of paraffinic mineral oil purified by combining one or more purification treatments such as washing and clay treatment alone or in combination of two or more, or normal paraffinic base oil, isoparaffinic base oil, etc., kinematic viscosity at 100 ° C, _A base oil in which% C _p and% C _A satisfy the above conditions can be used.

As a preferable example of the lubricating base oil according to the present invention, the following base oils (1) to (8) are used as raw materials, and the raw oil and / or a lubricating oil fraction recovered from the raw oil is determined in a predetermined manner. The base oil obtained by refine | purifying by the refining method of this, 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, the lubricating base oil according to the present invention is obtained by subjecting a base oil selected from the base oils (1) to (8) or a lubricating oil fraction recovered from the base oil to 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 a convenient 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.

100 ° C. The kinematic viscosity of the lubricating base oil of the invention must be less than or equal 20 mm ² / s, preferably 10 mm ² / s or less, more preferably ^{7 mm} 2 / s or less, more preferably 5. It is 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 100 ° C. kinematic viscosity 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 further preferably 2.5 mm. ² / s or more, particularly preferably 3 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 100 ° C. kinematic viscosity of the lubricating base oil component 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 ^{3.5~4.1mm 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.

Further, the kinematic viscosity at 40 ° C. of the lubricating base oil according to the present invention 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. 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. When the 40 ° C. kinematic viscosity of the lubricating base oil component exceeds 80 mm ² / s, the low-temperature viscosity characteristics may be deteriorated, and sufficient fuel economy may not be obtained, which is 6.0 mm ² / s or less. In such a case, the oil film formation at the lubrication site is insufficient, so that the lubricity is poor, and the evaporation loss of the lubricating oil composition may be increased. 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 etc.
(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 the present invention 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 invention depends on the viscosity grade of the lubricating base oil component, 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 component at 100 ° C. ]

When ρ ₁₅ > ρ, the viscosity-temperature characteristics and thermal / oxidation stability, as well as the volatilization prevention and low-temperature viscosity characteristics tend to be reduced, which may deteriorate the fuel economy. Moreover, when an additive is mix | blended with a lubricating base oil component, 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 the present invention is preferably 0.860 or less, more preferably 0.850 or less, still more preferably 0.840 or less, particularly preferably. 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 invention depends on the viscosity grade of the lubricating base oil. For example, the pour point of the lubricating base oils (I) and (IV) is preferably −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 points of the lubricating base oils (III) and (VI) are 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 the present invention 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. It is as follows. 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 the present invention 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 a raw material containing sulfur such as slack wax obtained in the refining process of the lubricating base oil or 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 invention, the sulfur content is preferably 100 mass ppm or less, more preferably 50 mass ppm 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.

  The nitrogen content in the lubricating base oil according to the present invention is not particularly limited, but is preferably 7 ppm by mass or less, more preferably 5 ppm by mass or less, and further preferably 3 ppm by mass 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.

Further, the% C _p of the lubricating base oil according to the present invention is preferably 70 or more, preferably 80 to 99, more preferably 85 to 95, still more preferably 87 to 94, and particularly preferably 90 to 94. It is. 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, additives are added to 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 invention 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 invention 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 the present invention is not particularly limited, but is preferably 90% by mass or more, preferably 95% by mass or more, more preferably, based on the total amount of the lubricating oil base oil. Is 99% by mass or more, and the ratio of the cyclic saturated component to 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 it is 25 mass% or less, More preferably, it is 21 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 an 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 consequently 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 invention is not particularly limited, but is preferably 5% by mass or less, more preferably 4% by mass or less, and still more preferably 3% by mass based on the total amount of the lubricating base oil. Hereinafter, it is particularly preferably 2% by mass or less, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, and particularly preferably 1.5% by mass or more. It is. 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. In addition, the lubricating base oil according to the present invention may not contain an aromatic component, but by further increasing the solubility of the additive by setting the aromatic content to the above lower limit or more. Can do.

  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, naphthols, and the like. Aromatic compounds having atoms are included.

  In the lubricating oil composition of the present invention, the lubricating base oil according to the present invention may be used alone, and the lubricating base oil according to the present invention may be one or more of other base oils. You may use together. When the lubricating base oil according to the present invention is used in combination with another base oil, the ratio of the lubricating base oil according to the present invention in the mixed base oil is preferably 30% by mass or more. 50% by mass or more is more preferable, and 70% by mass or more is more preferable.

Although it does not restrict | limit especially as another base oil used together with the lubricating base oil which concerns on this invention, As a mineral oil type | system | group base oil, kinematic viscosity in 100 degreeC is 1-100 mm < ² > / s, for example,% C _p and% C _a does not satisfy the above condition, solvent refined mineral oils, hydrocracked mineral oil, hydrotreated mineral oil, and the like solvent dewaxing base oil.

  In addition, as the synthetic base oil, the kinematic viscosity at 100 ° C. does not satisfy the above conditions, poly α-olefin or hydride thereof, isobutene oligomer or hydride thereof, isoparaffin, alkylbenzene, alkylnaphthalene, polyoxyalkylene glycol, Examples include dialkyl diphenyl ether and polyphenyl ether, and among them, poly α-olefin is preferable. 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.

  The lubricating oil composition according to the present invention contains (B) an ester compound.

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

  As the monohydric alcohol, those having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms are usually used. Such alcohols may be linear or branched, It may be saturated or unsaturated. Specific examples of the alcohol having 1 to 24 carbon atoms include methanol, ethanol, linear or branched propanol, linear or branched butanol, and linear or branched pentanol. , Linear or branched hexanol, linear or branched heptanol, linear or branched octanol, linear or branched nonanol, linear or branched decanol , Linear or branched undecanol, linear or branched dodecanol, linear or branched tridecanol, linear or branched tetradecanol, linear or branched Pentadecanol, linear or branched hexadecanol, linear or branched heptadecanol, linear or branched octadecanol, linear or branched nonade Nols, linear or branched icosanols, linear or branched heicosanols, linear or branched tricosanols, linear or branched tetracosanols, and mixtures thereof It is done.

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

  Among these polyhydric alcohols, ethylene glycol, diethylene glycol, polyethylene glycol (ethylene glycol 3-10 mer), propylene glycol, dipropylene glycol, polypropylene glycol (propylene glycol 3-10 mer), 1,3- Propanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, glycerin, diglycerin, triglycerin, trimethylolalkane (trimethylolethane, trimethylolpropane, trimethylol Methylol butane and the like, and dimers and tetramers thereof, pentaerythritol, dipentaerythritol, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetrio Le, 1,2,3,4 butane tetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, divalent to hexavalent polyhydric alcohols, and mixtures thereof, such as mannitol and the like are preferable. Furthermore, ethylene glycol, propylene glycol, neopentyl glycol, glycerin, trimethylol ethane, trimethylol propane, pentaerythritol, sorbitan, and a mixture thereof are more preferable. Among these, neopentyl glycol, trimethylol ethane, trimethylol propane, pentaerythritol, and a mixture thereof are most preferable because higher thermal / oxidative stability can be obtained.

  Of the acids constituting the ester compound used in the present invention, as the monobasic acid, a fatty acid having 2 to 24 carbon atoms is usually used, and the fatty acid may be linear or branched and saturated. Or unsaturated. Specifically, for example, acetic acid, propionic acid, linear or branched butanoic acid, linear or branched pentanoic acid, linear or branched hexanoic acid, linear or branched Branched heptanoic acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched decanoic acid, linear or branched undecanoic acid, Linear or branched dodecanoic acid, linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched Hexadecanoic acid, linear or branched heptadecanoic acid, linear or branched octadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, straight Chain or branched henicosanoic acid, linear or branched docosa Acid, linear or branched tricosanoic acid, saturated fatty acid such as linear or branched tetracosanoic acid, acrylic acid, linear or branched butenoic acid, linear or branched Pentenoic acid, linear or branched hexenoic acid, linear or branched heptenoic acid, linear or branched octenoic acid, linear or branched 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 tetradecene Acid, linear or branched pentadecenoic acid, linear or branched hexadecenoic acid, linear or branched heptadecenoic acid, linear or branched octadecenoic acid, linear or Branched nonadecenoic acid, linear or branched icosenoic acid, Unsaturated fatty acids such as 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. Among these, from the point that lubricity and handleability are further improved, saturated fatty acids having 3 to 20 carbon atoms, unsaturated fatty acids having 3 to 22 carbon atoms and mixtures thereof are particularly preferable, and saturated fatty acids having 4 to 18 carbon atoms. More preferable are unsaturated fatty acids having 4 to 18 carbon atoms and mixtures thereof, and saturated fatty acids having 4 to 18 carbon atoms are most preferable from the viewpoint of oxidative stability.

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

(B) The combination of the alcohol and the acid forming the ester compound is arbitrary and is not particularly limited. Examples of the ester that can be used in the present invention include the following esters, and these esters may be used alone. Moreover, you may combine 2 or more types.
(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 Ester (e) monohydric alcohol, mixture of polyhydric alcohol and polybasic acid (f) mixed ester of polyhydric alcohol with monobasic acid, polybasic acid (g) monohydric alcohol , Mixtures of polyhydric alcohols with monobasic acids and polybasic acids

  (B) As an ester compound, (a) ester of monohydric alcohol and monobasic acid, (b) ester of polyhydric alcohol and monobasic acid, (c) ester of monohydric alcohol and polybasic acid It is preferable to contain, and it is more preferable to contain (b) ester of polyhydric alcohol and monobasic acid. Further, the ester form is preferably a diester or a monoester, more preferably a diester, and particularly preferably a glycol diester.

  In the present invention, the ester obtained when a polyhydric alcohol is used as the alcohol component may be a complete ester in which all the hydroxyl groups in the polyhydric alcohol are esterified. A partial ester may be used. The organic acid ester obtained when a polybasic acid is used as the acid component may be a complete ester in which all the carboxyl groups in the polybasic acid are esterified, or a part of the carboxyl groups is not esterified and carboxylated. It may be a partial ester remaining as a group.

  The (B) ester compound preferably has 100 or less carbon atoms, more preferably 70 or less carbon atoms, and even more preferably 50 or less carbon atoms in that the fluidity can be further improved. The carbon number is particularly preferably 40 or less, and most preferably 30 or less.

  The (B) ester compound used in the present invention may be composed of only one kind of the above-described ester compound, or may be composed of a mixture of two or more kinds.

(B) is preferably a kinematic viscosity at 100 ° C. of the ester compound is 1 to 50 mm ² / s, preferably not more than 10 mm ² / s, more preferably 5.0 mm ² / s or less, more preferably 4.0 mm ² / S or less, particularly preferably 3.5 mm ² / s or less, and most preferably 3.0 mm ² / s or less. (B) When the kinematic viscosity at 100 ° C. of the ester compound is 50 mm ² / s or more, the viscosity temperature characteristic tends to deteriorate, the fuel economy tends to deteriorate, and the low temperature viscosity characteristic tends to become insufficient. The kinematic viscosity at 100 ° C. of (B) an ester compound is preferably 1 mm ² / s or more, more preferably 1.5 mm ² / s or higher, more preferably 2.0 mm ² / s or more, particularly preferably 2. 5 mm ² / s or more. (B) When the kinematic viscosity at 100 ° C. of the ester compound is less than 1 mm ² / s, oil film formation at the lubrication site tends to be insufficient and the lubricity tends to be reduced. The amount of loss tends to increase. (B) As an ester compound, as long as kinematic viscosity 1-100 mm < ² > / s in 100 degreeC is satisfy | filled individually, you may use together 1 type, or 2 or more types.

(B) The kinematic viscosity at 40 ° C. of the ester compound is preferably 100 mm ² / s or less, more preferably 30 mm ² / s or less, still more preferably 20 mm ² / s or less, particularly preferably 15 mm ² / s or less, and most preferably Is 10 mm ² / s or less. (B) If the ester compound has a kinematic viscosity at 40 ° C. of 100 mm ² / s or more, the viscosity-temperature characteristic is deteriorated and the required fuel-saving properties cannot be obtained, and the low-temperature viscosity characteristic becomes insufficient. there is a possibility. The kinematic viscosity at 40 ° C. of the (B) ester compound is preferably 1 mm ² / s or more, more preferably 3 mm ² / s or more, still more preferably 5 mm ² / s or more, and particularly preferably 6 mm ² / s or more. is there. When the kinematic viscosity at 40 ° C. of the base oil (A-1) is less than 1 mm ² / s, oil film formation at the lubrication site tends to be insufficient and the lubricity tends to decrease. The amount of evaporation loss tends to increase

  The viscosity index of the ester compound (B) is not particularly limited, but is preferably 40 or more, more preferably 100 or more, still more preferably 110 or more, particularly preferably 130 or more, and most preferably 150 or more. Further, it is preferably 250 or less, more preferably 220 or less, further preferably 200 or less, particularly preferably 190 or less. When the viscosity index is less than the lower limit, not only fuel economy and low-temperature viscosity characteristics are deteriorated, but heat / oxidation stability and volatilization prevention properties tend to be deteriorated. On the other hand, when the viscosity index exceeds the upper limit, fuel economy and low-temperature viscosity characteristics tend to deteriorate significantly. In addition, the viscosity index as used in the field of this invention means the viscosity index measured based on JISK2833-1993.

  (B) The acid value of the ester compound is not particularly limited, but is preferably 5 mgKOH or less, more preferably 3 mgKOH or less, still more preferably 2 mgKOH or less, particularly preferably 1.5 mgKOH or less, Preferably it is 1.0 mgKOH or less. Moreover, although it may be 0.2 mgKOH or less as one aspect of the present invention, it is preferably 0.2 mgKOH or more, more preferably 0.5 mgKOH or more from the viewpoint of economy in production. In addition, the lubricating oil composition excellent in oxidation stability can be obtained by the acid value of the said (B) component being 5 mgKOH or less.

  The content of the (B) ester compound is preferably 0.1 to 90% by mass based on the total amount of the base oil, more preferably 50% by mass or less, still more preferably 20% by mass or less, and particularly preferably 15% by mass. Hereinafter, it is most preferably 10% by mass or less. The lower limit is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, further preferably 2.0% by mass or more, and particularly preferably 4.0% by mass or more. (B) If the mixing ratio of the ester compound exceeds 90% by mass, oxidation stability, storage stability, and further fuel economy may be deteriorated, and (B) the mixing ratio of the ester compound is less than 0.1% by mass. In this case, the viscosity temperature characteristic is deteriorated, and there is a possibility that the required fuel saving performance cannot be obtained.

In the spectrum obtained by nuclear magnetic resonance analysis ( ¹³ C-NMR), the lubricating oil composition according to the present invention has a peak total area M 1 and a chemical shift 64- A viscosity index improver (C) having a ratio M1 / M2 of the total area M2 of peaks between 66 ppm of 0.20 or more is contained.

  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 is not 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 M1 of the peak between the chemical shifts 36-38 ppm relative to the total area of all peaks is the specific β-branch structure of the polymethacrylate side chain relative to the total integrated intensity of all carbons as measured by ¹³ C-NMR. The ratio of the integrated intensity derived from, the total area M2 of the peak between the chemical shifts 64-66 ppm relative to the total area of all peaks is the polymeta to the total integrated intensity of all carbons measured by ¹³ C-NMR. It means the proportion of the integrated intensity derived from a specific linear structure of the acrylate side chain.

M1 / M2 means a ratio of a specific β-branched structure and a specific linear structure of the polymethacrylate side chain, but other methods may be used as long as an equivalent result is obtained. In the 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, 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.

  The (C) viscosity index improver used in the present invention is not limited as long as the above conditions are satisfied. Non-dispersed or dispersed poly (meth) acrylate, non-dispersed or dispersed ethylene-α-olefin A copolymer or a hydride thereof, a polyisobutylene or a hydride thereof, a styrene-diene hydrogenated copolymer, a styrene-maleic anhydride ester copolymer and a polyalkylstyrene, or a mixture thereof can be used.

［式（１）中、Ｒ^１は水素またはメチル基を示し、Ｒ^２は炭素数１６以上の直鎖または分枝状の炭化水素基、あるいは、酸素および／または窒素を含有する炭素数１６以上の直鎖または分枝状の有機基を示す。］ The (C) viscosity index improver used in the present invention is preferably a poly (meth) acrylate, and a polymer having a proportion of structural units represented by the following formula (1) of 0.5 to 70 mol%. Preferably there is. The viscosity index improver may be either non-dispersed or dispersed.

[In the formula (1), R ¹ represents hydrogen or a methyl group, and R ² represents a straight chain or branched hydrocarbon group having 16 or more carbon atoms, or 16 or more carbon atoms containing oxygen and / or nitrogen. A linear or branched organic group. ]

R ² in formula (1) is preferably a linear or branched hydrocarbon group having 16 or more carbon atoms, more preferably a linear or branched hydrocarbon group having 18 or more carbon atoms. More preferably, it is a linear or branched hydrocarbon having 20 or more carbon atoms, particularly preferably a branched hydrocarbon group having 20 or more carbon atoms. The upper limit of the hydrocarbon group represented by R ² is not particularly limited, but is preferably a linear or branched hydrocarbon group having 100 or less carbon atoms. More preferably, it is a linear or branched hydrocarbon of 50 or less, more preferably a linear or branched hydrocarbon of 30 or less, particularly preferably 30 or less, a branched hydrocarbon. And most preferably 25 or less branched hydrocarbons.

  In the viscosity index improver, the proportion of the (meth) acrylate structural unit represented by the general formula (1) in the polymer is preferably 0.5 to 70 mol% as described above, and preferably 60 It is not more than mol%, more preferably not more than 50 mol%, still more preferably not more than 40 mol%, particularly preferably not more than 30 mol%. Further, it is preferably 1 mol% or more, more preferably 3 mol% or more, further preferably 5 mol% or more, and particularly preferably 10 mol% or more. If it exceeds 70 mol%, the effect of improving viscosity temperature characteristics and low temperature viscosity characteristics may be inferior, and if it is less than 0.5 mol%, the effect of improving viscosity temperature characteristics may be inferior.

  The viscosity index improver may contain a structural unit derived from an arbitrary (meth) acrylate structural unit or an arbitrary olefin in addition to the (meth) acrylate structural unit represented by the general formula (1).

  The method for producing the viscosity index improver is arbitrary, but for example, in the presence of a polymerization initiator such as benzoyl peroxide, a mixture of the monomer (M-1) and the monomers (M-2) to (M-4) Can be easily obtained by radical solution polymerization.

  The viscosity index improver preferably has a PSSI (Permanent Cystability Index) of 50 or less, more preferably 40 or less, still more preferably 35 or less, and particularly preferably 30 or less. Moreover, it is preferable that it is 5 or more, More preferably, it is 10 or more, More preferably, it is 15 or more, Most preferably, it is 20 or more. When PSSI is less than 5, the viscosity index improving effect is small and the cost may be increased. When PSSI is more than 50, shear stability and storage stability may be deteriorated.

The weight average molecular weight ( _Mw ) of the viscosity index improver is preferably 100,000 or more, more preferably 200,000 or more, still more preferably 250,000 or more, and particularly preferably 300,000. That's it. 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.

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 120,000. That's it. 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.

The weight average molecular weight and PSSI ratio of the viscosity index improver _(M W / PSSI) is preferably 0.8 × 10 ⁴ or more, preferably 1.0 × 10 ⁴ or more, more preferably 1.5 × 10 ⁴ or more, more preferably 1.8 × 10 ⁴ or more, and particularly preferably 2.0 × 10 ⁴ or more. If M _W / PSSI is below 0.8 × 10 ^4, there is a possibility that the viscosity-temperature characteristic is deteriorated i.e. deteriorates fuel efficiency.

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, and further Preferably it is 2.0 or more, Most preferably, it is 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.

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, still more preferably 3.0 or less, particularly Preferably it is 2.5 or less, Most preferably, it is 2.3 or less. Further, 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%.

The viscosity increase ratio ΔHTHS100 / ΔHTHS150 of the viscosity index improver at 100 ° C. and 150 ° C. is preferably 2.0 or less, more preferably 1.7 or less, still 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 SK YUBASE4, and ΔHTHS150 is SKBASE YUBASE4 with a viscosity index improver of 3.0%. 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. here refers to the high temperature and high shear viscosity at 100 ° C. 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 viscosity index improver in the lubricating oil composition of the present invention is preferably 0.01 to 50% by mass, more preferably 0.5 to 40% by mass, and still more preferably based on the total amount of the composition. Is 1 to 30% by mass, particularly preferably 5 to 20% by mass. 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. There is a concern that defects such as burn-in, seizure and fatigue failure may be the cause.

  In the lubricating oil composition of the present invention, a compound selected from an organic molybdenum compound and an ashless friction modifier can be further contained in order to improve fuel economy performance.

  Examples of the organic molybdenum compound used in the present invention include organic molybdenum compounds containing sulfur such as molybdenum dithiophosphate and molybdenum dithiocarbamate, molybdenum compounds (for example, molybdenum oxide such as molybdenum dioxide and molybdenum trioxide, orthomolybdic acid, paramolybdic acid). Molybdic acid such as (poly) sulfurized molybdate, metal salts of these molybdates, molybdate such as ammonium salts, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, molybdenum sulfide such as polysulfide molybdenum, sulfurized molybdenum acid Metal salts or amine salts of sulfurized molybdate, molybdenum halides such as molybdenum chloride, etc.) and sulfur-containing organic compounds (eg, alkyl (thio) xanthate, thiadiazole, mercaptothiadiazole, thioca Bonate, tetrahydrocarbyl thiuram disulfide, bis (di (thio) hydrocarbyl dithiophosphonate) disulfide, organic (poly) sulfide, sulfide ester, etc.) or other organic compounds, or the above molybdenum sulfide, sulfide And a complex of a sulfur-containing molybdenum compound such as molybdic acid and an alkenyl succinimide.

  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. Preference is given to complexes, molybdenum salts of organic acids and molybdenum salts of alcohols.

  In the lubricating oil composition of the present invention, when an organic molybdenum compound is used, its content is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0, in terms of molybdenum element, based on the total amount of the composition. 0.005% by mass or more, more preferably 0.01% by mass or more, particularly preferably 0.03% by mass or more, preferably 0.2% by mass or less, more preferably 0.1% by mass or less, Preferably it is 0.08 mass% or less, Most preferably, it is 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 of the present invention is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and still more preferably 0.3%, based on the total amount of the composition. It is at least 3% by mass, preferably at most 3% by mass, more preferably at most 2% by mass, even more preferably at most 1% by mass. 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. As the friction modifier, use of an ashless friction modifier is more preferable.

  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, ashless dispersants, antioxidants, antiwear agents (or extreme pressure agents), corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, Examples thereof include additives such as an antifoaming agent.

  Metal-based detergents include alkali salts such as alkali metal sulfonates or alkaline earth metal sulfonates, alkali metal phenates or alkaline earth metal phenates, and alkali metal salicylates or alkaline earth metal salicylates, basic normal salts or overbased salts. Etc. In the present invention, one or more alkali metal or alkaline earth metal detergents selected from the group consisting of these, particularly alkaline earth metal detergents can be preferably used. In particular, a magnesium salt and / or a calcium salt is preferable, and a calcium salt is more preferably used.

  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, 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.

  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, 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, sulfurized olefins, sulfurized fats and oils, and the like. Among these, addition of a sulfur-based extreme pressure agent is preferable, and sulfurized fats and oils are particularly preferable.

  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 of the present invention, the content thereof is 0.01 to 10% by mass based on the total amount of the composition.

Kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably from 4 to 12 mm ² / s, preferably 10 mm ² / s or less, more preferably 9.5 mm ² / s or less, more preferably 9 .0mm ² / s or less, particularly preferably not more than 8.5 mm ² / s. The kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably ^{5 mm} 2 / s or more, more preferably ^{6 mm} 2 / s or higher, more preferably 6.5 mm ² / s or more, particularly preferably 7 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 12 mm ² / s, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained. is there.

Kinematic viscosity at 40 ° C. of the lubricating oil composition of the present invention is preferably 4~50mm ² / s, preferably not more than 40 mm ² / s, more preferably 37 mm ² / s or less, particularly preferably 35 mm ² / s or less, most preferably 32 mm ² / s or less. Further, the kinematic viscosity at 40 ° C. of the lubricating oil composition of the present invention is preferably 10 mm ² / s or more, more preferably 20 mm ² / s or more, further preferably 25 mm ² / s or more, particularly preferably 27 mm ² / s. That's it. The kinematic viscosity at 40 ° C. here refers to 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 of the present invention 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 of the present invention is less than 140, it may be difficult to improve fuel efficiency while maintaining the HTHS viscosity at 150 ° C. Further, the low temperature viscosity at −35 ° C. There is a risk that it will be difficult to reduce. Further, when the viscosity index of the lubricating oil composition of the present invention is 400 or more, there is a possibility that the evaporability may be deteriorated, and there is a problem that the solubility of the additive and the compatibility with the sealing material are insufficient. There is a risk.

  The HTHS viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 5.5 mPa · s or less, more preferably 5.0 mPa · s or less, still 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. here refers to the high temperature and high shear viscosity at 100 ° C. 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 of the present invention is preferably 3.5 mPa · s or less, more preferably 3.0 mPa · s or less, still more preferably 2.8 mPa · s or less, particularly 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. here refers to 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.

The lubricating oil composition of the present invention is excellent in fuel economy and lubricity, and has a significantly improved viscosity index that is effective for improving fuel efficiency while maintaining the HTHS viscosity at a certain level. The lubricating oil composition of the present invention having such excellent characteristics can be suitably used as fuel-saving engine oils such as fuel-saving gasoline engine oil and fuel-saving diesel engine oil.

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

(Examples 1-4, Comparative Examples 1-2)
In Examples 1-4 and Comparative Examples 1-2, lubricating oil compositions were prepared using the following base oils and additives. Table 1 shows the properties of the base oil A-1, and Table 2 shows the composition of the lubricating oil composition.
(Base oil)
A-1 (base oil 1): mineral oil obtained by hydrocracking / hydroisomerizing n-paraffin-containing oil (additive)
B-1 (ester 1): oleic acid-2-ethylhexyl ester, 100 ° C. kinematic viscosity: 2.67 mm ² / s, 40 ° C. kinematic viscosity: 8.26 mm ² / s, viscosity index 183
B-2 (ester 2): neopentyl glycol-2-ethylhexyl ester, 100 ° C. kinematic viscosity: 2.05 mm ² / s, 40 ° C. kinematic viscosity: 7.47 mm ² / s, viscosity index 52
B-3 (ester 3): azelaic acid-2-ethylhexyl ester, 100 ° C. kinematic viscosity: 3.01 mm ² / s, 40 ° C. kinematic viscosity: 10.7 mm ² / s, viscosity index 146
B-4 (Ester 4): Trimethylolpropane triester, 100 ° C. kinematic viscosity: 4.41 mm ² / s, 40 ° C. kinematic viscosity: 19.6 mm ² / s, viscosity index 139
C-1: Polymethacrylate (methyl methacrylate, dimethylaminoethyl methacrylate and 90 mol% in total of methacrylates in which R ² in the above formula (2) is an alkyl group having 12 to 20 carbon atoms, 2) Copolymer with 10 mol% of methacrylate in which R ² is a branched alkyl group having 22 carbon atoms, 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 = 20000)
C-2: Distributed polymethacrylate (methyl methacrylate, methacrylate R ⁴ is a linear alkyl group having 12 carbon atoms in the above formula (3), Equation (3) R ⁴ is a number 13 carbons in linear chain alkyl group and is, methacrylate R ⁴ in the formula (3) is a linear alkyl group of 14 carbon atoms, R ⁴ in the formula (3) is a linear alkyl group having 15 carbon atoms Copolymer of methacrylate and dimethylaminoethyl methacrylate, 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)
D-1: Glycerol monooleate D-2: Molybdenum dithiocarbamate E-1: Metal detergent, ashless dispersant, antioxidant, antiwear agent, pour point depressant, antifoaming agent, etc.

[Evaluation of lubricating oil composition]
About each lubricating oil composition of Examples 1-4 and Comparative Examples 1-2, the kinematic viscosity in 40 degreeC or 100 degreeC, the viscosity index, and the HTHS viscosity in 150 degreeC were measured. Each physical property value was measured by the following evaluation method. 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

  As shown in Table 2, the compositions of Examples 1 to 4 which contain an ester compound and to which a predetermined viscosity index improver is added are the composition of Comparative Example 1 which does not contain an ester compound and the ratio of M1 / M2 Compared to the composition of Comparative Example 2 using a low viscosity index improver, the high viscosity index is high while maintaining high temperature and high shear viscosity at 150 ° C., indicating excellent fuel economy.

Claims (4)

A lubricating base oil having a kinematic viscosity at 100 ° C. of 1 to 20 mm ² / s;
An ester compound;
^{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 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, further comprising at least one compound selected from organic molybdenum compounds and ashless friction modifiers.