JP2010280820A - Lubricant composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant composition for imparting satisfactorily fuel-saving properties while keeping other practical performances such as durability. <P>SOLUTION: The lubricant composition contains a lubricant base oil having 1-5 mm<SP>2</SP>/s kinetic viscosity at 100°C and a viscosity index improver having ≥0.50 ratio M1/M2 (wherein M1 is the total area of peaks between 51-52.5 ppm chemical shift 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 and satisfies inequality (A): HTHS(100°C)/HTHS(150°C)≥0.50 (wherein HTHS(100°C) is the HTHS viscosity at 100°C; HTHS(150°C) is the HTHS viscosity at 150°C). <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 for internal combustion engines (engine oil) is required to have high performance as the internal combustion engine has higher performance, higher output, and severe operating conditions. Therefore, in order to satisfy such required performance, conventional engine oils are blended with various additives such as antiwear agents, metal detergents, ashless dispersants, antioxidants (for example, Patent Documents 1 to 3). ). In recent years, the fuel-saving performance required for lubricating oils has been increasing, and the application of high viscosity index base oils and various friction modifiers has been studied (for example, Patent Document 4).

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 constituting the lubricating oil, the lubricating performance under severe lubricating conditions (high temperature and high shear conditions) is reduced, 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 lower the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C. and the HTHS viscosity at 100 ° C., and further improve the low-temperature viscosity characteristics, but conventional lubricants satisfy all these requirements. It is very difficult.

  The present invention has been made in view of such circumstances, and the HTHS viscosity at 150 ° C. is sufficiently high, the kinematic viscosity at 40 ° C., the kinematic viscosity at 100 ° C., and the HTHS viscosity at 100 ° C. are sufficiently low, Is intended to provide a lubricating oil composition having excellent low-temperature viscosity characteristics.

In order to solve the above problems, the present invention comprises a lubricating base oil kinematic viscosity of 1 to 5 mm ² / s at 100 ° ^C., in a spectrum obtained by 13 C-NMR, chemical shifts relative to the total area of all peaks A ratio of the total area M1 of the peak between 51-52.5 ppm and the total area M2 of the peak between the chemical shifts 64-66 ppm, a viscosity index improver having M1 / M2 of 0.50 or more, And the lubricating oil composition characterized by the ratio of the HTHS viscosity in 150 degreeC and the HTHS viscosity in 100 degreeC satisfy | filling the conditions represented by a following formula (A) is provided.
HTHS (100 ° C.) / HTHS (150 ° C.) ≧ 0.50 (A)
[Wherein, HTHS (100 ° C.) represents the HTHS viscosity at 100 ° C., and HTHS (150 ° C.) represents the HTHS viscosity at 150 ° C. ]

  In the present invention, “HTHS viscosity at 150 ° C.” and “HTHS viscosity at 100 ° C.” mean high-temperature high-shear viscosity at 150 ° C. or 100 ° C. as defined in ASTM D4683, respectively.

  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 0.8 × 10 ⁴ or more.

  Here, “PSSI” in the present invention conforms to ASTM D 6022-01 (Standard Practicing for Calming of Permanent Shear Stability Index), and ASTM D 6278-02 (Test Method for Stood for Sto Permanent Shear Stability Index calculated based on data measured by European Diesel Injector Apparatus.

  The lubricating oil composition of the present invention preferably has an HTHS viscosity at 150 ° C. of 2.6 or more and an HTHS viscosity at 100 ° C. of 5.3 or less.

  The lubricating oil composition of the present invention has a sufficiently high HTHS viscosity at 150 ° C., a kinematic viscosity at 40 ° C., a kinematic viscosity at 100 ° C. and a HTHS viscosity at 100 ° C., and is excellent in low-temperature viscosity characteristics. is there. Therefore, according to the lubricating oil composition of the present invention, the HTHS viscosity at 150 ° C. is maintained 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. However, the fuel economy can be greatly improved, and particularly the HTHS viscosity at 100 ° C. and the kinematic viscosities at 40 ° C. and 100 ° C. of the lubricating oil can be greatly reduced to significantly improve the fuel economy.

  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.

In the lubricating oil composition of the present invention, a lubricating base oil (hereinafter referred to as “the lubricating base oil according to the present invention”) having a kinematic viscosity at 100 ° C. of 1 to 5 mm ² / s is 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 Among paraffinic mineral oils, normal paraffinic base oils, isoparaffinic base oils, etc. purified by combining one or more of purification processes such as washing and clay treatment alone or in combination, have a kinematic viscosity at 100 ° C. A base oil that satisfies 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 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.

100 ° C. The kinematic viscosity of the lubricating base oil of the invention must be less than or equal ^{5 mm} 2 / s, preferably 4.9 mm ² / s or less, more preferably 4.8 mm ² / s or less, further preferably 4.7 mm ² / s or less, particularly preferably 4.6 mm ² / s or less, and most preferably not more than 4.5 mm ² / s. 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 low temperature viscosity characteristics are deteriorated, and there may not be obtained sufficient fuel economy, in the case of less than 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 (B), that is, It is preferable that ρ ₁₅ ≦ ρ.
ρ = 0.0025 × kv100 + 0.816 (B)
[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 volatilization prevention and low-temperature viscosity characteristics tend to decrease, which may deteriorate 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, still more 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.

Further, 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 (C), that is, AP ≧ A is preferred.
A = 4.3 × kv100 + 100 (C)
[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.

  Further, 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 amount of NOACK evaporation in the lubricating base oil according to the present invention is not particularly limited, but is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably. It is 9 mass% or less, Most preferably, it is 8 mass% or less. When the NOACK evaporation amount is equal to or less than the above upper limit value, it is possible to achieve low evaporation and improve cleanliness. Moreover, it is preferable that NOACK evaporation is 1 mass% or more, More preferably, it is 3 mass% or more, More preferably, it is 5 mass% or more. If the NOACK evaporation amount is less than or equal to the above lower limit value, not only the required fuel economy can be obtained but also the low temperature viscosity characteristics may be deteriorated. In addition, the NOACK evaporation amount as used in the field of this invention means the evaporation loss amount (measuring conditions: 250 degreeC, 1 hour) measured based on ASTMD 5800-95.

Further, the% C _p of the lubricating base oil according to the present invention is preferably 70 or more, more preferably 80 to 99, still more preferably 85 to 95, particularly preferably 87 to 94, and most preferably 90 to 90. 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 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.

In addition, the content of the saturated component in the lubricating base oil according to the present invention is not particularly limited as long as the kinematic viscosity at 100 ° C. and% C _p and% C _A satisfy the above conditions. As a standard, it is preferably 90% by mass or more, preferably 95% by mass or more, more preferably 99% by mass or more, and the ratio of the cyclic saturated component in the saturated component is preferably 40% by mass or less. Yes, preferably 35% by mass or less, preferably 30% by mass or less, more preferably 25% by mass or less, and still 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.

Also, the aromatic content in the lubricating base oil of the invention has a kinematic viscosity at 100 ° C.,% but C _p and% C _A is not particularly limited so far as it meets the above conditions, based on the lubricating base oils the total amount , Preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less, particularly preferably 2% by mass or less, and preferably 0.1% by mass or more, more preferably 0. It is 5% by mass or more, more preferably 1% by mass or more, and particularly preferably 1.5% by 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 invention may not contain an aromatic component, but by further increasing the solubility of the additive by setting the aromatic content to be 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 and naphthols. Aromatic compounds having atoms are included.

  Further, the urea adduct value in the lubricating base oil according to the present invention is preferably 5% by mass or less, more preferably from the viewpoint of improving the low temperature viscosity characteristics without impairing the viscosity-temperature characteristics and obtaining high thermal conductivity. Is 3% by mass or less, more preferably 2.5% by mass or less, and particularly preferably 2% by mass or less. The urea adduct value may be 0% by mass, but a sufficient low temperature viscosity characteristic and a lubricating base oil having a higher viscosity index can be obtained, and the dewaxing conditions are eased and the economy is excellent. And preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 0.8% by mass or more.

Here, the urea adduct value means a value measured by the following method.
100 g of weighed sample oil is put into a round bottom flask, 200 mg of urea, 360 ml of toluene and 40 ml of methanol are added and stirred at room temperature for 6 hours. As a result, white granular crystals are produced as urea adducts in the reaction solution. The reaction solution is filtered through a 1 micron filter to collect the produced white granular crystals, and the obtained crystals are washed 6 times with 50 ml of toluene. The recovered white crystals are put in a flask, 300 ml of pure water and 300 ml of toluene are added, and the mixture is stirred at 80 ° C. for 1 hour. The aqueous phase is separated and removed with a separatory funnel, and the toluene phase is washed three times with 300 ml of pure water. A desiccant (sodium sulfate) is added to the toluene phase for dehydration, and then toluene is distilled off. The ratio (mass percentage) of the urea adduct obtained in this way to the sample oil is defined as the urea adduct value.

  In measurement of urea adduct value, when urea adduct is used, isoparaffin which adversely affects low-temperature viscosity characteristics, component which deteriorates thermal conductivity, or normal paraffin remains in lubricating base oil This normal paraffin can be collected accurately and reliably, so that it is excellent as a low-temperature viscosity characteristic and thermal conductivity evaluation index of a lubricating base oil. The inventors of the present invention have analyzed by using GC and NMR that the main component of the urea adduct is a normal paraffin and an isoparaffin urea adduct having 6 or more carbon atoms from the end of the main chain to the branch position. Confirm that there is.

  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 still more preferable.

The other base oil used in combination with the lubricating base oil according to the present invention is not particularly limited. For example, the kinematic viscosity at 100 ° C. is 5 to 500 mm ² / s, and% C _p and% C _A are the above. Examples thereof include mineral base oils such as solvent refined mineral oil, hydrocracked mineral oil, hydrorefined mineral oil, solvent dewaxed base oil, and synthetic base oils that do not satisfy the conditions. By blending another base oil with the lubricating base oil according to the present invention, the high temperature cleanability of the lubricating oil composition is improved.

If the lubricating oil compositions of the present invention using a mineral base oil as another base oil preferably has a kinematic viscosity at 100 ° C. is 5 to 500 mm ² / s, preferably 5.3 mm ² / s or more, more Preferably it is 5.5 mm < ² > / s or more, More preferably, it is 5.7 mm < ² > / s or more, Most preferably, it is 5.9 mm < ² > / s or more. The upper limit is more preferably 100 mm ² / s or less, further preferably 50 mm ² / s or less, particularly preferably 30 mm ² / s or less, most preferably 20 mm ² / s or less, and most preferably 10 mm ² / s or less. It is. When the kinematic viscosity at 100 ° C. of other base oils is less than 5 mm ² / s, the high temperature cleanability may be lowered. When the kinematic viscosity at 100 ° C. exceeds 500 mm ² / s, the viscosity-temperature characteristics As a result, the required fuel economy cannot be obtained, and the low-temperature viscosity characteristics may be deteriorated.

  The viscosity index of other base oils is not particularly limited, but is preferably 80 or more, more preferably 100 or more, still more preferably 120 or more, particularly preferably 130 or more, and most preferably 135 or more. Further, it is preferably 180 or less, more preferably 170 or less, still more preferably 160 or less, and particularly preferably 150 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, the low-temperature viscosity characteristics tend to deteriorate significantly.

  The NOACK evaporation amount of other base oils is not particularly limited, but is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and particularly preferably 8% by mass or less. Preferably it is 7 mass% or less. When the NOACK evaporation amount is equal to or less than the above upper limit value, it is possible to achieve low evaporation and improve cleanliness. Moreover, it is preferable that NOACK evaporation is 1 mass% or more, More preferably, it is 3 mass% or more, More preferably, it is 5 mass% or more. If the NOACK evaporation amount is less than or equal to the above lower limit value, not only the required fuel economy can be obtained but also the low temperature viscosity characteristics may be deteriorated.

  Synthetic base oils include, for example, poly-α-olefin or hydride thereof, isobutene oligomer or hydride thereof, isoparaffin, alkylbenzene, alkylnaphthalene; ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl Diesters such as adipate and di-2-ethylhexyl sebacate; polyol esters such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate; polyoxyalkylene glycol, dialkyldiphenyl ether And polyphenyl ether. Among them, poly α-olefin is preferable. The poly α-olefin is typically an oligomer or co-oligomer of α-olefin having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms, such as 1-octene oligomer, decene oligomer, ethylene-propylene co-oligomer, 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 viscosity index improver that can be used in the present invention is a total peak area M1 between 51 and 52.5 ppm in chemical shift with respect to the total area of all peaks in the spectrum obtained by nuclear magnetic resonance analysis ( ^13C -NMR). And the ratio M1 / M2 of the total area M2 of the peak between the chemical shift and 64-66 ppm is 0.50 or more.

  M1 / M2 is preferably 1.0 or more, more preferably 2.0 or more, particularly preferably 3.0 or more, and most preferably 4.0 or more. M1 / M2 is preferably 10 or less, more preferably 9.0 or less, particularly preferably 8.0 or less, and most preferably 7.0 or less. When M1 / M2 is less than 0.50, not only the required fuel saving performance is not obtained, but also the low temperature viscosity characteristics may be deteriorated. Moreover, when M1 / M2 exceeds 10, not only the required fuel-saving property cannot be obtained but also the solubility and storage stability may be deteriorated.

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 the chemical shift 51-52.5 ppm relative to the total area of all peaks is the specific 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 methyl structure, the total area of the peak (M2) between the chemical shifts 64-66 ppm relative to the total area of all peaks is the integrated intensity of all carbons measured by ¹³ C-NMR. The ratio of the integrated intensity derived from the specific linear structure of the polymethacrylate side chain to the total of

M1 / M2 means the ratio of a specific methyl structure and a specific straight chain structure of the polymethacrylate side chain, but other methods may be used as long as equivalent results are 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 a chemical shift of about 10-70 ppm (sum of integral intensities due to total carbon of the hydrocarbon), and (b) Sum of integral intensities with a chemical shift of 51-52.5 ppm (specific methyl structure) And (c) total integrated intensity with a chemical shift of 64-66 ppm (total integrated intensity due to a specific linear structure)
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.

［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 viscosity index improver used in the present invention is preferably a poly (meth) acrylate, and is a polymer in which the proportion of structural units represented by the following formula (1) is 0.5 to 70 mol%. It is preferable. 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 more than 6.0, not only the solubility in the base oil and the storage stability are deteriorated, but also the viscosity-temperature characteristics are deteriorated, that is, the fuel economy may be deteriorated. There is.

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 required to be 0.01 to 50% by mass, preferably 0.5% by mass or more, based on the total amount of the composition. Preferably it is 1 mass% or more, Especially preferably, it is 2 mass% or more, Most preferably, it is 5 mass% or more. Further, it is preferably 40% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less. 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, as a viscosity index improver, in addition to the above-described viscosity index improver, an ordinary general non-dispersed or dispersed poly (meth) acrylate, non-dispersed or dispersed ethylene -Α-olefin copolymer or hydrogenated product thereof, polyisobutylene or hydrogenated product thereof, styrene-diene hydrogenated copolymer, styrene-maleic anhydride ester copolymer, polyalkylstyrene and the like can further be contained. .

In the lubricating oil composition of the present invention, a friction modifier selected from an organic molybdenum compound and an ashless friction modifier can be contained in order to further improve fuel economy performance.
Examples of the organic molybdenum compound include organic molybdenum compounds containing sulfur such as molybdenum dithiophosphate and molybdenum dithiocarbamate.

  Other sulfur-containing organic molybdenum compounds include complexes of molybdenum compounds with sulfur-containing organic compounds or other organic compounds, or sulfur-containing molybdenum compounds such as molybdenum sulfide and sulfurized molybdenum acid, and alkenyl succinic acid. Examples include complexes with imides.

  Examples of the molybdenum compound include molybdenum oxide such as molybdenum dioxide and molybdenum trioxide; molybdic acid such as orthomolybdic acid, paramolybdic acid and (poly) sulfurized molybdic acid, and molybdic acid such as metal salts and ammonium salts of these molybdic acids. Examples thereof include molybdenum sulfides such as salts, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, and polysulfide molybdenum, molybdenum sulfides, metal salts of molybdenum sulfides, amine salts, and molybdenum halides such as molybdenum chloride.

  Examples of the sulfur-containing organic compound include alkyl (thio) xanthate, thiadiazole, mercaptothiadiazole, thiocarbonate, tetrahydrocarbyl thiuram disulfide, bis (di (thio) hydrocarbyl dithiophosphonate) disulfide, organic (poly) sulfide, Examples include sulfurized esters.

As the organomolybdenum compound, an organomolybdenum compound containing no sulfur as a constituent element can also be used.
Examples of organic molybdenum compounds not containing sulfur include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, molybdenum salts of alcohols, among others, molybdenum-amine complexes, molybdenum of organic acids. Salts and molybdenum salts of alcohols are preferred.

  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, preferably 0.2% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, particularly Preferably it is 0.03 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.

  As the ashless friction modifier, any compound usually used as a friction modifier for lubricating oils can be used, for example, an alkyl group or alkenyl group having 6 to 50 carbon atoms, particularly 6 to 50 carbon atoms. Examples include amine compounds, amide compounds, imide compounds, and ester compounds having at least one linear alkyl group or linear alkenyl group in the molecule. Further examples include ashless friction modifiers such as fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea friction modifiers, and the like.

  When the ashless friction modifier is used in the lubricating oil composition of the present invention, the content of the ashless friction modifier is preferably 0.01% by mass or more, more preferably 0.1% by mass, based on the total amount of the composition. % Or more, more preferably 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 invention, either one of the organic molybdenum compound or the ashless friction modifier may be used, or both may be used together, but the ashless friction modifier can be maintained for a longer period of time. It is more preferable to use

  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, pour point depressants, demulsifiers, metals Examples thereof include additives such as an inactivating agent and an antifoaming agent.

  Examples of metal detergents include normal salts such as alkali metal sulfonates or alkaline earth metal sulfonates, alkali metal phenates or alkaline earth metal phenates, alkali metal salicylates or alkaline earth metal salicylates, basic normal salts or overbased Salt. 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 These are 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, as the phenol-based ashless antioxidant, for example, 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert- Examples of amine-based ashless antioxidants include 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, and sulfur-phosphorus extreme pressure agents can be used. Specifically, for example, phosphites, thiophosphites, dithiophosphites, trithiophosphites, phosphate esters, thiophosphates, dithiophosphates, trithiophosphorus Examples include acid esters, amine salts thereof, metal salts thereof, derivatives thereof, dithiocarbamate, zinc dithiocarbamate, molybdenum dithiocarbamate, disulfides, polysulfides, sulfurized olefins, and sulfurized fats and oils. 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, and imidazole compounds.

  Examples of the rust inhibitor include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester.

  As the pour point depressant, for example, a polymethacrylate-based polymer compatible with the lubricating base oil to be used can be used.

  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. Dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, or β- (o-carboxybenzylthio) propiononitrile.
Examples of antifoaming agents include silicone oils having a kinematic viscosity at 25 ° C. of less than 0.1 to 100 mm ² / s, alkenyl succinic acid derivatives, esters of polyhydroxy aliphatic alcohols and long chain fatty acids, methyl salicylates and o -Hydroxybenzyl alcohol.

  When these additives are contained in the lubricating oil composition of the present invention, the content thereof is preferably 0.01 to 10% by mass based on the total amount of the composition.

The ratio of the HTHS viscosity at 150 ° C. and the HTHS viscosity at 100 ° C. of the lubricating oil composition of the present invention must satisfy the condition represented by the following formula (A). If the ratio is less than 0.50, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained.
HTHS (100 ° C.) / HTHS (150 ° C.) ≧ 0.50 (A)
[Wherein, HTHS (100 ° C.) represents the HTHS viscosity at 100 ° C., and HTHS (150 ° C.) represents the HTHS viscosity at 150 ° C. ]
For the same reason, HTHS (100 ° C.) / HTHS (150 ° C.) is more preferably 0.51 or more, further preferably 0.52 or more, particularly preferably 0.53 or more, and most preferably 0.54. That's it.

  The HTHS viscosity at 150 ° C. of the lubricating oil composition of the present invention is not particularly limited, but 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 2.1 mPa · s or more, further preferably 2.2 mPa · s or more, particularly preferably 2.3 mPa · s or more, and most preferably 2.4 mPa · s or more. It is. 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 HTHS viscosity at 100 ° C. of the lubricating oil composition of the present invention is not particularly limited, but is preferably 5.3 mPa · s or less, more preferably 5.2 mPa · s or less, even more preferably 5.1 mPa · s or less, particularly Preferably, it is 5.0 mPa · s or less. Further, it is preferably 3.5 mPa · s or more, more preferably 3.8 mPa · s or more, particularly preferably 4.0 mPa · s or more, and most preferably 4.2 mPa · s or more. When the HTHS viscosity at 100 ° C. is less than 3.5 mPa · s, there is a risk of insufficient lubricity, and when it exceeds 5.3 mPa · s, the necessary low temperature viscosity and sufficient fuel saving performance cannot be obtained. There is a fear.

Kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably from 3 to 15 mm ² / s, more preferably 12 mm ² / s or less, more preferably 10 mm ² / s or less, particularly preferably 9 mm ² / S or less, and most preferably 8 mm ² / s or less. The kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is more preferably 4 mm ² / s or more, further preferably 5 mm ² / s or more, particularly preferably 6 mm ² / s or more, and most preferably 7 mm ² / s. s or more. If the kinematic viscosity at 100 ° C. is less than 3 mm ² / s, there is a risk of insufficient lubricity, and if it exceeds 15 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 not particularly limited, usually 4~80mm ² / s, preferably not more than 50 mm ² / s, more preferably 45 mm ² / s or less, more preferably 40 mm ² / S or less, particularly preferably 35 mm ² / s or less, and most preferably 33 mm ² / s or less. Further, it 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. If the kinematic viscosity at 40 ° C. is less than 4 mm ² / s, the lubricity may be insufficient. If it exceeds 80 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 not particularly limited, but is preferably in the range of 140 to 400, more preferably 180 or more, still more preferably 190 or more, still more preferably 200 or more, and particularly preferably 210. That's it. When the viscosity index is less than 140, it may be difficult to improve fuel economy while maintaining the HTHS viscosity, and it may be difficult to reduce the low temperature viscosity at -35 ° C. is there. On the other hand, when the viscosity index exceeds 400, low-temperature fluidity is deteriorated, and there is a possibility that problems due to insufficient solubility of the additive and compatibility with the sealing material may occur.

  The lubricating oil composition of the present invention is excellent in fuel economy, lubricity and high temperature cleanliness, and does not use a synthetic oil such as a poly-α-olefin base oil or an ester base oil or a low viscosity mineral oil base oil. Even so, 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 a certain level, are significantly reduced. 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 more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Examples 1-6, Comparative Examples 1-3]
In Examples 1 to 6 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, and the evaluations shown below were performed. Table 1 shows the properties of the base oils 1 to 3.
(Base oil)
Base oil 1: Base oil obtained by hydrocracking / hydroisomerizing n-paraffin-containing oil Base oil 2: Hydrocracked base oil Base oil 3: Hydrocracked base oil
(Additive)
A-1: Non-dispersed polymethacrylate (M1 = 5.8, M2 = 0.95, M1 / M2 = 6.1, ΔKV40 / ΔKV100 = 2.2, ΔHTHS100 / ΔHTHS150 = 1.51, MW = 400 , 000, PSSI = 20, Mw / Mn = 2.2, Mw / PSSI = 20000)
A-2: Non-dispersed polymethacrylate (M1 = 0.19, M2 = 3.69, M1 / M2 = 0.05, ΔKV40 / ΔKV100 = 4.4, ΔHTHS100 / ΔHTHS150 = 2.15, MW = 80, 000, Mw / Mn = 2.7, PSSI = 5, Mw / PSSI = 16000)
A-3: Dispersed polymethacrylate (M1 = 1.5, M2 = 3.52, M1 / M2 = 0.43, ΔKV40 / ΔKV100 = 3.3, ΔHTHS100 / ΔHTHS150 = 1.79, MW = 300,000 PSSI = 40, Mw / Mn = 4.0, Mw / PSSI = 7500)
B-1 (friction modifier 1): glycerin monooleate B-2 (friction modifier 2): oleyl urea B-3 (friction modifier 3): molybdenum dithiocarbamate C-1 (additive) Contains ashless dispersant, antioxidant, phosphorus antiwear agent, pour point depressant, defoamer, etc.

<Evaluation of lubricating oil composition>
About each lubricating oil composition of Examples 1-6 and Comparative Examples 1-3, kinematic viscosity at 40 ° C. and 100 ° C., viscosity index, HTHS viscosity at 100 ° C. and 150 ° C., CCS viscosity at −35 ° C., and panel coking test The amount of deposit was measured. Each measurement was performed by the following evaluation methods. The results are shown in Table 2.
(1) Kinematic viscosity: ASTM D-445
(2) Viscosity index: JIS K 2283-1993
(3) HTHS viscosity: ASTM D4683
(4) CCS viscosity: ASTM D5293
(5) High temperature cleanliness test: After testing using a panel coking tester under conditions of oil temperature 100 ° C., panel temperature 280 ° C., splash time 3 hours, ON / OFF cycle = 15 s / 45 s. The amount of deposit (mg) adhered to the panel was measured.

From Table 2, the composition of Examples 1-6 which added the predetermined viscosity index improver is excellent in a viscosity temperature characteristic and a low-temperature viscosity characteristic. Furthermore, the compositions of Examples 1 to 3 blended with a high-viscosity base oil having a 100 ° C. kinematic viscosity of 5 to 500 mm ² / s have a small deposit amount and excellent high-temperature cleanliness. On the other hand, the compositions of Comparative Examples 1 to 3 to which a viscosity index improver other than the predetermined one is added have high kinematic viscosity (40 ° C.) and HTHS viscosity (100 ° C.) and are inferior in viscosity temperature characteristics.

Claims (4)

A lubricating base oil having a kinematic viscosity at 100 ° C. of 1 to 5 mm ² / s;
^{In the} spectrum obtained by ¹³ C-NMR, the ratio of the total area M1 of peaks between chemical shift 51-52.5 ppm to the total area of all peaks and the total area M2 of peaks between chemical shifts 64-66 ppm, M1 / A viscosity index improver having M2 of 0.50 or more;
And the ratio of the HTHS viscosity at 150 ° C. to the HTHS viscosity at 100 ° C. satisfies the condition represented by the following formula (A).
HTHS (100 ° C.) / HTHS (150 ° C.) ≧ 0.50 (A)
[Wherein, HTHS (100 ° C.) represents the HTHS viscosity at 100 ° C., and HTHS (150 ° C.) represents the HTHS viscosity at 150 ° C. ]   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 weight average molecular weight to PSSI ratio of 0.8 × 10 ⁴ or more.   The lubricating oil composition according to any one of claims 1 to 3, wherein the HTHS viscosity at 150 ° C is 2.6 or more and the HTHS viscosity at 100 ° C is 5.3 or less.