JP6334503B2 - Lubricating oil composition and method for producing the same - Google Patents

Description

  The present invention relates to a lubricating oil composition, for example, a lubricating oil composition for an internal combustion engine used in a gasoline engine.

  In recent years, environmental regulations have been strengthened, and fuel efficiency of automobile engines has been demanded. Therefore, introduction of a supercharged direct injection engine equipped with a direct injection mechanism and a supercharging mechanism has been promoted. In the supercharged direct injection engine, by increasing the torque at low speed rotation, the displacement can be reduced while maintaining the output, so that the fuel efficiency can be improved.

  On the other hand, engine oils used in automobile engines usually contain various additives. For example, molybdenum dialkyldithiocarbamate is added to reduce the friction coefficient between metals and improve fuel economy. It has been known. In addition, for the purpose of ensuring cleanliness, preventing wear, preventing sludge, etc., metallic detergents containing calcium and magnesium, various phosphorus-containing compounds, and ashless detergents such as borated dispersants are blended. It is also known that.

  Among gasoline engines, supercharged direct injection engines are prone to abnormal combustion called low-speed pre-ignition. Therefore, various improvements have been made in engine oil in order to reduce the frequency of low-speed pre-ignition. . For example, in Patent Document 1, it is known that the blending amounts of various additives are adjusted so that the calcium amount, magnesium amount, molybdenum amount, phosphorus amount, and nitrogen amount contained in the engine oil satisfy a specific relational expression. It has been. Here, in the specific example of the engine oil disclosed in Patent Literature 1, the blending amount of molybdenum is suppressed to 0.01 to 0.04 mass% while keeping the calcium amount or the magnesium amount constant.

WO2015 / 114920

However, as in the specific example disclosed in Patent Document 1, when the amount of molybdenum is suppressed, it may be difficult to reduce the coefficient of friction between metals.
Further, it is known that it is effective to reduce the calcium content in engine oil in order to suppress low speed pre-ignition. However, in engine oils containing molybdenum dialkyldithiocarbamate, reducing the calcium content may increase the coefficient of friction. Furthermore, in engine oils containing molybdenum dialkyldithiocarbamate and having a molybdenum content of a predetermined amount or more, high-temperature cleanliness often deteriorates.Therefore, many detergent dispersants may be blended. Many of them increase the coefficient of friction.
That is, it is difficult to achieve both improvement in high temperature cleanliness and reduction in the friction coefficient in engine oil in which the molybdenum content is a predetermined amount or more and the calcium content is reduced.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to provide high-temperature cleanliness while containing molybdenum dialkyldithiocarbamate and having a molybdenum content of a predetermined amount or more and a low calcium content. It is providing the lubricating oil composition which can implement | achieve a low friction coefficient, ensuring.

As a result of intensive studies, the inventors of the present invention, in a lubricating oil composition containing a molybdenum dialkyldithiocarbamate compound, having a molybdenum content of a predetermined amount or more and a low calcium content, We found that the above problems can be solved by adjusting the amount of magnesium derived from the detergent, the amount of boron derived from the boron-containing compound, and the content of the ashless friction modifier so as to satisfy the predetermined relational expression, and the present invention was completed. I let you. The present invention provides the following lubricating oil composition.
A lubricating oil composition comprising a lubricating base oil, a metallic detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound,
The metallic detergent is
Calcium salicylate,
Containing at least one selected from the group consisting of calcium sulfonates and magnesium-based detergents,
The lubricating oil composition optionally contains an ashless friction modifier,
In the lubricating oil composition, the content of calcium atoms is 0.12 to 0.16% by mass based on the total amount of the lubricating oil composition, and the content of molybdenum atoms is 0.05 to 0 based on the total amount of the lubricating oil composition. .10% by weight,
And the lubricating oil composition whose X computed by following formula (1) is less than 0.050.
X = 3.8 × 10 ⁻² −2.7 × 10 ⁻⁴ × [A] −4.2 × 10 ⁻¹ × [B] + 5.4 × 10 ⁻¹ × [C] −5.2 × 10 ⁻³ × [D] + 7.3 × 10 ⁻³ × [E] (1)
(In the above formula (1),
[A] is a proportion (mass%) of the soap derived from calcium sulfonate out of the total mass of soap derived from calcium salicylate, calcium sulfonate and calcium phenate,
[B] is a magnesium atom content (mass%) of the magnesium-based detergent,
[C] is the content (% by mass) of boron atoms contained in the lubricating oil composition,
[D] is the content (mass%) of the ashless friction modifier,
[E] is E calculated by the following equation (2).
E = ([A] +1) × ([B] +0.001) (2)
Represents. The values [B] to [D] are values based on the total amount of the lubricating oil composition. )

Furthermore, the present invention also provides the following method for producing a lubricating oil composition.
A method for producing a lubricating oil composition comprising at least a metallic detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound in a lubricating base oil to obtain a lubricating oil composition,
The metallic detergent is
Calcium salicylate,
Containing at least one selected from the group consisting of calcium sulfonates and magnesium-based detergents,
The lubricant base oil may optionally contain an ashless friction modifier,
In the lubricating oil composition, the content of calcium atoms is 0.12 to 0.16% by mass based on the total amount of the lubricating oil composition, and the content of molybdenum atoms is 0.05 to 0.5 based on the total amount of the lubricating oil composition. 0.10% by mass,
And the manufacturing method of the lubricating oil composition adjusted so that X computed by following formula (1) might be less than 0.050.
X = 3.8 × 10 ⁻² −2.7 × 10 ⁻⁴ × [A] −4.2 × 10 ⁻¹ × [B] + 5.4 × 10 ⁻¹ × [C] −5.2 × 10 ⁻³ × [D] + 7.3 × 10 ⁻³ × [E] (1)
(In the above formula (1),
[A] is a proportion (mass%) of the soap derived from calcium sulfonate out of the total mass of soap derived from calcium salicylate, calcium sulfonate and calcium phenate,
[B] is a magnesium atom content (mass%) of the magnesium-based detergent,
[C] is the content (% by mass) of boron atoms contained in the lubricating oil composition,
[D] is the content (mass%) of the ashless friction modifier,
[E] is E calculated by the following equation (2).
E = ([A] +1) × ([B] +0.001) (2)
Represents. [B] to [D] are values based on the total amount of the lubricating oil composition. )

  In the present invention, a lubricating oil composition comprising a molybdenum compound having a dialkyldithiocarbamate compound and capable of realizing a low friction coefficient while ensuring high-temperature cleanliness even though the molybdenum content is a predetermined amount or more and a low calcium content. I will provide a.

Hereinafter, the present invention will be described using embodiments.
The lubricating oil composition of the present embodiment contains a lubricating base oil, a metallic detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound, and further optionally contains an ashless friction modifier, The metallic detergent contains calcium salicylate and at least one selected from the group consisting of calcium sulfonate and magnesium detergent.
The lubricating oil composition has a calcium atom content in the composition of 0.12 to 0.16% by mass based on the total amount of the lubricating oil composition, and a molybdenum atom content in the composition. The content of various additives is adjusted such that X is 0.05 to 0.10% by mass based on the total amount of the lubricating oil composition and X calculated by the following formula (1) is less than 0.050. It is a thing.
X = 3.8 × 10 ⁻² −2.7 × 10 ⁻⁴ × [A] −4.2 × 10 ⁻¹ × [B] + 5.4 × 10 ⁻¹ × [C] −5.2 × 10 ⁻³ × [D] + 7.3 × 10 ⁻³ × [E] (1)
(In the above formula (1),
[A] is the ratio (mass%) of the soap derived from calcium sulfonate out of the total mass of the soap derived from calcium salicylate, calcium sulfonate and calcium phenate,
[B] is a magnesium atom content (mass%) of the magnesium-based detergent,
[C] is the content (% by mass) of boron atoms contained in the lubricating oil composition,
[D] is the content (mass%) of the ashless friction modifier,
[E] is E calculated by the following equation (2).
E = ([A] +1) × ([B] +0.001) (2)
Represents. The values [B] to [D] are values based on the total amount of the lubricating oil composition. )

In the present embodiment, when the amount of calcium and the amount of molybdenum in the composition are within the above-described certain ranges, the value of “X” calculated in the above formula (1) is measured by a block-on-ring test described later. The value approximates the friction coefficient between metals. That is, the smaller the value of “X”, the lower the coefficient of friction between metals and the easier it is to obtain good fuel consumption characteristics. On the other hand, when the value of X is 0.050 or more, the coefficient of friction also increases, making it difficult to improve fuel efficiency.
Here, the lower the value of X, the greater the effect of reducing the friction coefficient. Therefore, X is preferably 0.045 or less, more preferably 0.042 or less, and 0.040 or less. More preferably it is.
Further, the lower limit of X is not particularly limited, but is preferably 0.015 or more from the viewpoint of balance with other performances required for the lubricating oil composition, and the like. More preferably.

In this embodiment, when the content of calcium atoms or the content of molybdenum atoms is outside the above range, the value of X is not a value approximated to the friction coefficient, and the value of X is set to less than 0.050. However, the value of the friction coefficient may not be sufficiently low.
Furthermore, if the amount of calcium exceeds the above upper limit value, for example, when used as engine oil for a supercharged direct injection engine, it is difficult to suppress the frequency of occurrence of low speed pre-ignition. Moreover, when the amount of molybdenum exceeds the upper limit, problems such as deterioration in high temperature cleanliness tend to occur.
From these viewpoints, based on the total amount of the lubricating oil composition, the content of calcium atoms in the lubricating oil composition is preferably 0.12 to 0.16% by mass, and preferably 0.12 to 0.15% by mass. Is more preferable, and it is further more preferable that it is 0.12-0.14 mass%. Moreover, it is preferable that content of the molybdenum atom in a lubricating oil composition is 0.05-0.09 mass%, and it is further more preferable that it is 0.05-0.08 mass%.
Further, based on the total amount of the lubricating oil composition, the content of boron atoms contained in the lubricating oil composition is 0.01 from the viewpoint of ensuring good high temperature cleanliness while maintaining the friction coefficient sufficiently low. It is preferable that it is -0.15 mass%, 0.01-0.10 mass% is more preferable, 0.01-0.05 mass% is further more preferable. It is preferable that all boron atoms in the lubricating oil composition are derived from a boron-containing compound (boron-based detergent dispersant) described later.

The total content of calcium atoms and magnesium atoms in the lubricating oil composition is preferably 0.3% by mass or less based on the total amount of the lubricating oil composition. When the total content is 0.3% by mass or less, the ash content is lowered, and therefore, there is no possibility of clogging the exhaust gas purification post-treatment device such as a gasoline particulate filter. Further, the total content is more preferably 0.25% by mass or less, and further preferably 0.20% by mass or less.
The total content of calcium atoms and magnesium atoms in the composition is 0.12% by mass or more, preferably 0.13% by mass or more, and more preferably 0.14% by mass or more. By increasing the total content, the base number of the lubricating oil composition described later can be easily set to 4 mgKOH / g or more.
The magnesium atom content in the lubricating oil composition is preferably 0.14% by mass or less, more preferably 0.10% by mass or less, and even more preferably 0.08% by mass or less, based on the total amount of the lubricating oil composition. is there.
The total amount of calcium atoms and magnesium atoms in the lubricating oil composition is preferably derived from a metal detergent described later.

Hereinafter, each component contained in the lubricating oil composition will be described in more detail.
[Lubricant base oil]
The lubricating base oil may be a mineral oil, a synthetic oil, or a mixed oil of a mineral oil and a synthetic oil.
As mineral oil, for example, a lubricating oil fraction obtained by distillation under reduced pressure of atmospheric residual oil obtained by atmospheric distillation of crude oil can be desolvated, solvent extracted, hydrocracked, solvent dewaxed, catalytic dehydrated. Mineral oil refined by one or more of wax, hydrorefining, etc., or mineral oil produced by isomerizing wax produced by mineral oil-based wax or Fischer-Tropsch method (GTL wax) Etc.
On the other hand, synthetic oils include polyolefins such as polybutene, α-olefin homopolymers and copolymers (for example, ethylene-α-olefin copolymers), various esters such as polyol esters, dibasic acid esters, and phosphate esters. And various ethers such as polyphenyl ether, polyglycol, alkylbenzene, alkylnaphthalene and the like.
The lubricating base oil may be used alone or in combination of two or more.

The kinematic viscosity at 100 ° C. of the lubricating base oil is preferably ² to 15 mm ² / s, more preferably ^{2 to 10} mm ² / s, and further preferably 3 to 5 mm ² / s.
If the kinematic viscosity at 100 ° C. of the base oil is equal to or higher than the lower limit, it is preferable because the evaporation loss is small. On the other hand, if the kinematic viscosity is less than or equal to the above upper limit value, the power loss due to the viscous resistance is not so large, and the fuel efficiency improvement effect is easily obtained.
The lubricating base oil preferably has a paraffin content (may be described as% Cp) by ndM ring analysis of 70% or more, preferably 75% or more, and 80% or more. It is more preferable that Lubricating oil base oil becomes easy to make oxidation stability etc. favorable because a paraffin part becomes below the said lower limit. Further, the lubricating base oil has a kinematic viscosity at 100 ° C. of 3 to 5 mm ² / s and a% Cp of 80% or more, so that the oxidation stability is easily improved.
Furthermore, the viscosity index of the lubricating base oil is preferably 80 or higher, more preferably 90 or higher, and still more preferably 100 or higher in order to improve fuel economy while suppressing changes in viscosity due to temperature changes.
In addition, also when using the mixed oil which combined 2 or more types of base oil in a lubricating oil composition, it is preferable that the kinematic viscosity of the said mixed oil, a viscosity index, and% Cp are the said ranges.
The content of the lubricating base oil in the lubricating oil composition is preferably 65 to 95% by mass, more preferably 70 to 95% by mass, and even more preferably 70 to 90% by mass based on the total amount of the lubricating oil composition.

[Metal-based detergent]
The metallic detergent used in the present embodiment contains calcium salicylate. In this embodiment, the use of calcium salicylate makes it easier to improve the high temperature cleanliness.
The content of calcium salicylate in terms of calcium atom is preferably 0.08 to 0.16% by mass, more preferably 0.10 to 0.16% by mass, based on the total amount of the lubricating oil composition, and 0.10 to 0.06. 14 mass% is more preferable.

In addition to calcium salicylate, the metallic detergent further contains at least one of calcium sulfonate and magnesium detergent. In this embodiment, by using a calcium sulfonate and / or a magnesium-based detergent as the metal detergent, it becomes easy to reduce the coefficient of friction while improving the high temperature cleanability.
In addition, although calcium sulfonate and a magnesium type detergent may use these two together, you may use only any one.
Examples of the magnesium detergent include magnesium salicylate, magnesium sulfonate, and magnesium phenate, and it is preferable to use magnesium sulfonate. These may be used individually by 1 type and may mix 2 or more types. Although the base number of a magnesium type detergent is not specifically limited, Preferably it is 10-500 mgKOH / g, More preferably, it is 200-450 mgKOH / g, More preferably, it is 300-450 mgKOH / g.

Here, when calcium sulfonate is contained in the lubricating oil composition, the content of calcium sulfonate in terms of calcium atoms is preferably 0.01 to 0.05 mass% based on the total amount of the lubricating oil composition, and 0.01 -0.04 mass% is more preferable, and 0.01-0.03 mass% is further more preferable.
When the magnesium-based detergent is contained in the lubricating oil composition, the magnesium-based conversion content of the magnesium-based detergent is preferably 0.01 to 0.14% by mass based on the total amount of the lubricating oil composition, 0.01-0.10 mass% is more preferable. And when using together with calcium sulfonate, the content in terms of magnesium atom is more preferably 0.02 to 0.06 mass%, and when using alone without using calcium sulfonate, the content is 0.04 to More preferably, it is 0.08 mass%.

The metal detergent may contain a metal detergent other than calcium salicylate, calcium sulfonate, and magnesium detergent. Such metal detergents include calcium phenates and metal detergents other than calcium detergents and magnesium detergents. Examples of metal detergents other than calcium detergents and magnesium detergents include barium detergents, sodium detergents, and potassium detergents.
However, the metal detergent contained in the lubricating oil composition is preferably composed of a metal detergent selected from the group consisting of calcium detergents and magnesium detergents.

In this embodiment, it is possible to adjust the value of a friction coefficient by adjusting the amount of soap contained in the calcium-based detergent among the above. Specifically, the ratio of the soap derived from calcium sulfonate to the total mass of the soap derived from calcium salicylate, calcium sulfonate and calcium phenate (hereinafter also simply referred to as “sulfonate soap”) is increased. Thus, the friction coefficient can be lowered.
Therefore, in the above formula (1), a negative coefficient is added to [A] representing the sulfonate soap, which is subtracted from the value of X. Note that the coefficient “−2.7 × 10 ⁻⁴ ” multiplied by the coefficient [A] takes into consideration the influence of the sulfonate soap content on the friction coefficient in the lubricating oil composition of the present embodiment by experiment and analysis thereof. It is calculated.

The sulfonate soap (that is, calcium sulfonate) is preferably contained in the lubricating oil composition in order to easily reduce the friction coefficient, but may not be contained in the lubricating oil composition. Even if the lubricating oil composition does not contain sulfonate soap, it is possible to adjust X within the above-mentioned range by adjusting [B] to [E].
In addition, when the sulfonate soap is contained, the proportion of the sulfonate soap in the total mass of the soap derived from calcium salicylate, calcium sulfonate and calcium phenate is preferably 10 to 75% by mass, and 20 to 70% by mass. % Is more preferable, and 25-65 mass% is further more preferable.

In the lubricating oil composition, the magnesium-based detergent tends to reduce the friction coefficient. Therefore, in the above formula (1), [B] representing the magnesium amount derived from the magnesium-based detergent is subtracted from the value of X with a negative coefficient. The coefficient “−4.2 × 10 ⁻¹ ” multiplied by the coefficient [B] was calculated by taking into consideration the influence of magnesium on the friction coefficient in the lubricating oil composition of the present embodiment by experiment and analysis thereof. Is.
Furthermore, when the lubricating oil composition contains both a sulfonate soap (ie, calcium sulfonate) and a magnesium-based detergent, the friction coefficient tends to increase due to the interaction of these components. The factor [E] in the formula (1) indicates this interaction. In this lubricating oil composition, the coefficient of friction is generally high by the factor [E] multiplied by 7.3 × 10 ^−3. This is found by experiment and analysis thereof, and 7.3 × 10 ⁻³ × [E] is added to the value “X” in the equation (1).

The calcium sulfonate or magnesium sulfonate described above preferably has a calcium salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a weight average molecular weight of 300 to 1,500, more preferably 400 to 700, or A magnesium salt is mentioned.
Examples of calcium phenate or magnesium phenate include calcium salts or magnesium salts of Mannich reaction products of alkylphenols, alkylphenol sulfides, and alkylphenols.
Furthermore, calcium salicylate or magnesium salicylate includes calcium or magnesium salts of alkyl salicylic acid.
The alkyl group contained in each of these calcium-based detergents or magnesium-based detergents is preferably one having 4 to 30 carbon atoms, more preferably one having 10 to 26 carbon atoms. It may be a branch. These may be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

In addition, as each of the above calcium-based detergents or magnesium-based detergents, the above-mentioned alkyl aromatic sulfonic acid, alkylphenol, alkylphenol sulfide, Mannich reaction product of alkylphenol, alkyl salicylic acid, etc. are directly used for alkaline earth metals (that is, calcium or Magnesium) or a neutral salt obtained by reacting with an alkali metal salt such as a sodium salt or a potassium salt and then substituting it with an alkaline earth metal salt. Things (neutral salts) can be used.
Alternatively, it may be obtained by heating the neutral salt obtained as described above and an excess of an alkaline earth metal salt or alkaline earth metal base in the presence of water, or the above The neutral salt obtained as described above may be obtained by reacting with an alkaline earth metal carbonate or borate in the presence of carbon dioxide gas.
Among the above-mentioned calcium-based detergents, the use of a neutral salt can increase the proportion of soap in the calcium-based detergent. In addition, by adjusting the amount of calcium salt, calcium base, borate, carbon dioxide used to act on calcium sulfonate, calcium phenate, calcium salicylate, etc., the amount of soap contained in the calcium detergent It is also possible to adjust.

[Molybdenum dialkyldithiocarbamate compound]
Specific examples of the molybdenum dialkyldithiocarbamate compound (hereinafter also simply referred to as “molybdenum compound”) used in the present embodiment include compounds represented by the following formula (I).

[In Formula (I), R ^{1 to} R ⁴ represent an alkyl group having ⁴ to 22 carbon atoms, and R ^{1 to} R ⁴ may be the same or different. X < ¹ > -X < ⁴ > represents a sulfur atom or an oxygen atom. ]

In general formula (I), when the number of carbon atoms is 4 or more, the oil solubility of the molybdenum compound is improved. Moreover, since melting | fusing point becomes comparatively low and it becomes 22 or less, handling property becomes favorable, and friction reduction ability also becomes high. From these viewpoints, R ^{1 to} R ⁴ preferably have 4 to 18 carbon atoms, and more preferably 8 to 13 carbon atoms.
The alkyl group for R ^{1 to} R ⁴ may be either a branched or straight chain alkyl group. Examples of preferred alkyl groups include n-octyl group, 2-ethylhexyl group, isononyl group, n-decyl group, isodecyl group, dodecyl group, tridecyl group, isotridecyl group and the like.
In addition, from the viewpoint of solubility in base oil, storage stability and friction reducing ability, the molybdenum compound represented by the general formula (I) is an alkyl group in which R ¹ and R ² are the same, and an alkyl group in which R ³ and R ⁴ are the same. It is preferable that the alkyl groups of R ¹ and R ² are different from the alkyl groups of R ³ and R ⁴ .

Further, in general formula ^(I), X 1 to X ⁴ represents a sulfur atom or an oxygen ^atom, X 1 to to X ⁴ may be the same or different. The ratio of sulfur atom to oxygen atom is preferably sulfur atom / oxygen atom = 1/3 to 3/1, more preferably 1.5 / 2.5 to 3/1. Within the above range, good performance can be obtained in terms of corrosion resistance and solubility in lubricating base oil. Further, all of X ^{1 to} X ⁴ may be sulfur atoms or oxygen atoms.

  In this embodiment, it is preferable that all molybdenum atoms in the lubricating oil composition are derived from the molybdenum compound. Therefore, the molybdenum compound in the lubricating oil composition preferably has a molybdenum atom content of 0.05 to 0.10 mass% based on the total amount of the lubricating oil composition, and 0.05 to 0.09 mass. % Is more preferable, and 0.05 to 0.08 mass% is further more preferable.

[Boron-containing compounds]
The boron-containing compound used in the present embodiment may be a cleaning dispersant (boron-based cleaning dispersant), and specifically, borated dispersant, alkali metal borate, borated epoxide, boric acid. Examples include esters, borated fatty amines, and borated amides. A boron containing compound may be used individually by 1 type, and 2 or more types may be mixed and used for it.
By using these boron-containing compounds, the high temperature cleanability of the lubricating oil composition can be improved.

The borated dispersant is an ashless dispersant, and more specifically, for example, borated polyalkenyl succinic anhydride; non-nitrogen-containing borated derivatives of polyalkylene succinic anhydride; succinimides, carvone Acid amides, hydrocarbon monoamines, hydrocarbon polyamines, Mannich bases, phosphonoamides, thiophosphonoamides and phosphoramides, thiazoles, mercaptobenzothiazoles (eg, 2,5-dimercapto-1,3 , 4-thiadiazoles) and their derivatives, triazoles (eg alkyltriazoles and benzotriazoles), co-polymers containing carboxylic acid esters with one or more additional polar functional groups including amines, amides, imines, imides, etc. Coalesced (eg long chain alkyl acrylate or methacrylate) A product produced by copolymerization of a monomer having a functional group with the above-mentioned functional group), a borate of a basic nitrogen compound (borated basic nitrogen compound) selected from the group consisting of: Can be mentioned.
Preferred borated dispersants include borated succinimides.

Examples of the borated succinimides include alkenyl or alkyl succinic acid monoimides, or alkenyl or alkyl succinic acid bisimides that are borated.
Examples of the alkenyl or alkyl succinic acid monoimide include compounds represented by the following general formula (II). Examples of the alkenyl or alkyl succinic acid bisimide include compounds represented by the following general formula (III).

In the general formulas (II) and (III), R ²¹ , R ²³ and R ²⁴ are alkenyl groups or alkyl groups, and the weight average molecular weights are preferably 500 to 3,000, more preferably 900 to 3,000, respectively. 3,000.
When the weight average molecular weight of R ²¹ , R ²³ and R ²⁴ is 500 or more, the solubility in the lubricating base oil can be improved. Moreover, when it is 3,000 or less, it is expected that the effect obtained by the present compound is appropriately exhibited. R ²³ and R ²⁴ may be the same or different.
R ²² , R ²⁵ and R ²⁶ are each an alkylene group having 2 to 5 carbon atoms, and R ²⁵ and R ²⁶ may be the same or different. a represents an integer of 1 to 10, and b represents 0 or an integer of 1 to 10.
Here, a is preferably 2 to 5, more preferably 2 to 4. It is expected that the effect obtained by borated succinimides can be easily obtained when a is 2 or more. When a is 5 or less, the solubility in the lubricating base oil becomes even better.
Moreover, b is preferably 1-6, more preferably 2-6. When b is 1 or more, it is expected that the effect obtained by the present compound is appropriately exhibited. When b is 6 or less, the solubility in the lubricating base oil is further improved.

  Examples of the alkenyl group include a polybutenyl group, a polyisobutenyl group, and an ethylene-propylene copolymer, and examples of the alkyl group include those obtained by hydrogenation thereof. Suitable alkenyl groups include polybutenyl or polyisobutenyl groups. As the polybutenyl group, a mixture of 1-butene and isobutene or a polymer obtained by polymerizing high-purity isobutene is preferably used. A representative example of a suitable alkyl group is a hydrogenated polybutenyl group or polyisobutenyl group.

For example, the borated succinimide is obtained by reacting a polyolefin with maleic anhydride to obtain an alkenyl succinic anhydride, and further reacting a polyamine with a boron compound to obtain an intermediate. And alkenyl succinic anhydride can be obtained by reacting and imidizing. Monoimides or bisimides can be made by changing the ratio of alkenyl succinic anhydride or alkyl succinic anhydride to polyamine.
Further, borated succinimides can also be produced by treating boron-free alkenyl or alkyl succinic monoimide or alkenyl or alkyl succinic bisimide with a boron compound.
Examples of the boron compound used here include boric acid, borates, and borate esters. Examples of boric acid include orthoboric acid, metaboric acid, and paraboric acid. Examples of the borate include ammonium borate such as ammonium metaborate, ammonium tetraborate, ammonium pentaborate, and ammonium octaborate. As borate esters, monomethyl borate, dimethyl borate, trimethyl borate, monoethyl borate, diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, Examples thereof include dibutyl borate and tributyl borate.

The alkali metal atom contained in the alkali metal borate is not particularly limited as long as it is an alkali metal atom, but is preferably a potassium atom or a sodium atom, and more preferably a potassium atom.
Borate is an electrically positive compound (salt) containing boron and oxygen and optionally hydrated. Examples of borates include salts of borate ions (BO ₃ ³⁻ ) and salts of metaborate ions (BO ₂ ⁻ ). The borate ions (BO ₃ ³⁻ ) are, for example, triborate ions (B ₃ O ₅ ⁻ ), tetraborate ions (B ₄ O ₇ ²⁻ ), pentaborate ions (B ₅ O ₈ ^−). ) And the like can form various polymer ions.

Specific examples of the alkali metal borate include sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, sodium diborate, potassium metaborate, potassium triborate, and tetraborate. Examples include potassium, potassium pentaborate, potassium hexaborate, and potassium octaborate. The alkali metal borate may be a hydrate. Among alkali metal borates, potassium triborate (KB ₃ O ₅ ) and its hydrates (KB ₃ O ₅ .5) from the viewpoint of improving cleanliness at high temperatures and solubility in base oils. nH ₂ O (n is a number of 0.5 to 2.4)) is preferable.

  Examples of the borated epoxides include those obtained from a reaction product of one or more boron compounds and at least one epoxide. The epoxide is generally an aliphatic epoxide having 8 to 30 carbon atoms, preferably 10 to 24 carbon atoms, more preferably about 12 to 20 carbon atoms. Suitable aliphatic epoxides include dodecene oxide, hexadecene oxide and the like and mixtures thereof.

Examples of boric acid esters include those obtained by reacting one or more of the boron compounds with one or more suitable lipophilic alcohols. Alcohols generally have 6 to 30 carbon atoms, preferably 8 to 24 carbon atoms. The boric acid esters may be borated phospholipids.
Examples of borated fatty amines include those obtained by reacting at least one of boron compounds with at least one of fatty amines such as amines having 14 to 18 carbon atoms. By reacting an amine and a boron compound at a temperature in the range of 50 to 300 ° C., preferably 100 to 250 ° C., in an equivalent ratio of amine to boron compound of 3: 1 to 1: 3, borated fatty amines are obtained. Can be manufactured.

Examples of borated amides include borated amides obtained from reaction products of linear or branched, saturated or unsaturated monovalent fatty acids having 8 to 22 carbon atoms, urea and polyalkylene polyamines, and boric acid compounds. And the like.
Specific examples of boron compounds used in producing borated epoxides, boric acid esters, borated fatty amines, and borated amides include boron oxide, boron oxide hydrate, and boron trioxide. And boron trifluoride, boron tribromide, boron trichloride, boronic acid such as boronic acid, boric acid, tetraboric acid and metaboric acid, boron amides, and various esters of boronic acid.

  Among the above boron-containing compounds, borated dispersants are preferable, and borated succinimides are particularly preferable. The borated succinimides may be used alone, but borated succinimides are used in combination with at least one selected from the above boron-containing compounds other than the borated succinimides. May be.

In the lubricating oil composition of the present embodiment, the boron-containing compound improves the high temperature cleanliness, while the boron content increases the friction coefficient. However, as long as the relational expression (1) is satisfied, the friction coefficient is increased. It can be kept low enough. The boron content was found by experiments and analysis to increase the friction coefficient by an amount obtained by multiplying the boron atom content [C] by 5.4 × 10 ⁻¹ , and therefore the value “X” The value of 5.4 × 10 ⁻¹ × [C] is added as shown in Equation (1).
The boron-based content of the boron-containing compound in the lubricating oil composition is 0 on the basis of the total amount of the lubricating oil composition from the viewpoint of ensuring good high-temperature cleanliness while maintaining the friction coefficient sufficiently low. It is preferable that it is 0.01-0.15 mass%, 0.01-0.10 mass% is more preferable, 0.01-0.05 mass% is further more preferable.
Furthermore, from the viewpoint of ensuring high temperature cleanliness while lowering the friction coefficient, the boron atom content contained in the lubricating oil composition is 0.1 to 0.1% relative to the molybdenum atom content in the lubricating oil composition. 0.8 is preferable, 0.2 to 0.7 is more preferable, and 0.3 to 0.6 is more preferable.

[Ashless friction modifier]
The lubricating oil composition in the present embodiment may contain an ashless friction modifier, but may not contain it. The lubricating oil composition can have a lower friction coefficient by containing an ashless friction modifier. On the other hand, it becomes easy to make high temperature cleanliness good by not containing an ashless friction modifier.
Examples of the ashless friction modifier include ester-based ashless friction modifiers and amine-based ashless friction modifiers. As an ashless friction modifier, you may use individually by 1 type and may be used in combination of 2 or more type.

Examples of ester-based ashless friction modifiers include esters of fatty acids and aliphatic alcohols. Examples of the fatty acid include a linear or branched aliphatic monocarboxylic acid having a hydrocarbon group having 6 to 30 carbon atoms, and the hydrocarbon group preferably has 8 to 24 carbon atoms, more preferably 10 to 10 carbon atoms. 20. In addition, a hydrocarbon group here means the hydrocarbon part remove | excluding the carboxyl group of the fatty acid.
As the aliphatic alcohol, an aliphatic polyhydric alcohol is used. The fatty acid and aliphatic alcohol ester may be a partial ester in which only a part of the alcohol is esterified, or may be a complete ester in which all the alcohols are esterified, but usually a partial ester is used. Is done.

  Examples of the linear or branched hydrocarbon group having 6 to 30 carbon atoms include hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, Alkyl groups such as hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, penticosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group and triacontyl group; Hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, nonadecenyl group, icosenyl group, An alkenyl group such as a nicocosenyl group, a dococenyl group, a tricocenyl group, a tetracocenyl group, a pentacocenyl group, a hexacocenyl group, a heptacocenyl group, an octacocenyl group, a nonacosenyl group and a triaconenyl group, a hydrocarbon group having two or more double bonds, etc. Can be mentioned. In addition, the hydrocarbon group having two or more alkyl groups, alkenyl groups, and double bonds includes all possible linear structures and branched structures, and includes two alkenyl groups and two double bonds. The position of the double bond in the hydrocarbon group having the above is arbitrary.

  Specific examples of fatty acids include saturated fatty acids such as caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid, myristoleic acid, and palmitoleic acid. Unsaturated fatty acids such as oleic acid and linolenic acid, unsaturated fatty acids are preferred, and oleic acid is more preferred.

The aliphatic polyhydric alcohol is a divalent to hexavalent alcohol, and examples thereof include ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitol, and glycerin is preferable.
That is, as the ester-based ashless friction modifier, an ester of glycerin and the above aliphatic monocarboxylic acid is preferable. The ester may be a complete ester, but is preferably a partial ester, and more preferably a partial ester obtained by a reaction between glycerin and the unsaturated fatty acid. Specific examples include monoesters such as glycerin monomyristate, glycerin monopalmitate, and glycerin monooleate, and diesters such as glycerin dimyristate, glycerin dipalmitrate, and glycerin dioleate.

  Examples of amine-based ashless friction modifiers include aliphatic amine compounds, which are linear or branched amine compounds having a hydrocarbon group having 6 to 30 carbon atoms. The hydrocarbon group of the amine compound preferably has 8 to 24 carbon atoms, more preferably 10 to 20 carbon atoms. Examples of the hydrocarbon group having 6 to 30 carbon atoms include those exemplified as the hydrocarbon group of the fatty acid.

  Examples of the aliphatic amine compound include an aliphatic monoamine or an alkylene oxide adduct thereof, an alkanolamine, an aliphatic polyamine, an imidazoline compound, and the like. Specifically, laurylamine, lauryldiethylamine, lauryldiethanolamine, dodecyldipropanolamine, palmitylamine, stearylamine, stearyltetraethylenepentamine, oleylamine, oleylpropylenediamine, oleyldiethanolamine, and N-hydroxyethyloleylimidazoline, etc. Examples include aliphatic amine compounds and amine alkylene oxide adducts such as N, N-dipolyoxyalkylene-N-alkyl (or alkenyl) (carbon number 6 to 28) of these aliphatic amine compounds.

  As the ashless friction modifier, ester-based ashless friction modifiers are preferable, and as described above, esters of glycerin and fatty acids are more preferable. Particularly, glycerin monooleate and glycerindiolate which are partial esters of glycerin and oleic acid. Is more preferable.

In the lubricating oil composition according to the present embodiment, the ashless friction modifier is found by experiments and analyzes thereof to reduce the friction coefficient by an amount obtained by multiplying the content [D] by 5.2 × 10 ^−3. In Expression (1), the value of 5.2 × 10 ⁻³ × [D] is subtracted from “X”.
When the ashless friction modifier is contained in the lubricating oil composition, it is preferably 0.2 to 1.8 mass%, more preferably 0.2 to 1.7 mass%, based on the total amount of the lubricating oil composition. More preferably, it is 0.2-1.5 mass%.

[Boron-free ashless detergent / dispersant]
The lubricating oil composition in the present embodiment may contain boron-free succinimides as a boron-free ashless detergent / dispersant. By containing boron-free succinimides, the high temperature cleanliness can be further improved.
Examples of succinimides include alkenyl or alkyl succinic monoimide, or alkenyl or alkyl succinic bisimide. Examples of the alkenyl or alkyl succinic acid monoimide include compounds represented by the above general formula (II). Examples of the alkenyl or alkyl succinic acid bisimide include the compounds represented by the general formula (III).
The boron-free succinimide is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and further preferably 1 to 4% by mass based on the total amount of the lubricating oil composition.

[Other additives]
The lubricating oil composition may further contain additives for lubricating oil such as viscosity index improvers, pour point depressants, antiwear agents, antioxidants, and antifoaming agents. These may be used singly or in combination of two or more.
(Viscosity index improver)
Examples of the viscosity index improver include polymethacrylate-based, olefin-based copolymers such as ethylene-propylene copolymer, and styrene-based copolymers such as styrene-diene hydrogenated copolymer. Polymethacrylate is preferred. The polymethacrylate type may be either a dispersion type or a non-dispersion type.
The weight average molecular weight of the polymethacrylate viscosity index improver is preferably 10,000 to 1,000,000, more preferably 100,000 to 800,000, and still more preferably 300,000 to 600,000. The weight average molecular weight is a value obtained by measuring by GPC and using polystyrene as a calibration curve.
The viscosity index improver is preferably 0.1 to 15% by mass, more preferably 0.5 to 12% by mass, and still more preferably 1 to 12% by mass based on the total amount of the lubricating oil composition.

(Pour point depressant)
Examples of the pour point depressant include ethylene-vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene and the like.
The pour point depressant is preferably 0.01 to 2% by mass, more preferably 0.05 to 1% by mass, and still more preferably 0.1 to 0.5% by mass, based on the total amount of the lubricating oil composition. .

(Antiwear agent)
Antiwear agents include sulfur-containing compounds such as zinc dithiophosphate, zinc phosphate, zinc dithiocarbamate, disulfides, thiocarbonates, thiocarbamates; phosphites, phosphates, phosphonates, And phosphorus-containing compounds such as amine salts thereof; sulfur and phosphorus-containing compounds such as thiophosphites, thiophosphates, thiophosphonates, and amine salts thereof. Among these, zinc dithiophosphate is preferred, and zinc dialkyldithiophosphate is a more preferred specific example.
The antiwear agent is preferably contained in an amount of 0.01 to 4% by mass, more preferably 0.05 to 3% by mass, and still more preferably 0.1 to 2% by mass, based on the total amount of the lubricating oil composition.

(Antioxidant)
The lubricating oil composition may further contain an antioxidant. Antioxidants include amine-based antioxidants, phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, etc. Among these, amine-based antioxidants and phenol-based antioxidants are used. preferable. These can be arbitrarily selected from known antioxidants conventionally used as antioxidants for lubricating oils.
Examples of amine-based antioxidants include diphenylamines and diphenylamines such as dialkyldiphenylamines having an alkyl group having 3 to 20 carbon atoms; naphthylamines such as α-naphthylamine and alkyl-substituted phenyl-α-naphthylamines having 3 to 20 carbon atoms. The one of the system is mentioned.
Examples of the phenolic antioxidant include 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, and octadecyl-3- (3,5 Monophenols such as -di-tert-butyl-4-hydroxyphenyl) propionate; 4,4'-methylenebis (2,6-di-tert-butylphenol), 2,2'-methylenebis (4-ethyl- 6-tert-butylphenol) and the like.
Examples of the sulfur-based antioxidant include dilauryl-3,3′-thiodipropionate, and examples of the phosphorus-based antioxidant include phosphite.
These antioxidants can be contained alone or in any combination of two or more kinds, but it is usually preferable to use two or more kinds in combination, and an amine antioxidant and a phenolic antioxidant are combined. It is more preferable.
The content of the antioxidant is preferably 0.01 to 10% by mass, preferably 0.1 to 5% by mass, and more preferably 0.5 to 3% by mass based on the total amount of the composition.

(Defoamer)
Examples of antifoaming agents include silicone oil and fluorosilicone oil. The content of the antifoaming agent is preferably 0.1 to 30 ppm by mass, more preferably 0.5 to 15 ppm by mass, and further preferably 1 to 10 ppm by mass in terms of silicone.

<Physical properties of lubricating oil composition>
The lubricating oil composition of this embodiment preferably has a base number of 4 to 10 mgKOH / g or more. By setting the base number of the lubricating oil composition to 4 mgKOH / g or more, it becomes possible to suppress the formation of deposits in the engine during high-temperature operation, prevent sludge accumulation, and keep the engine interior clean. Further, it is possible to neutralize acidic substances generated due to deterioration of engine oil and the like, thereby preventing corrosion wear. Moreover, it becomes easy to make content of the calcium atom and magnesium atom in a lubricating oil composition low by making a base number into 10 mgKOH / g or less.
From the above viewpoint, the base number of the lubricating oil composition is more preferably 5 to 10 mgKOH / g, and further preferably 6 to 10 mgKOH / g.

The lubricating oil composition of the present embodiment preferably has a kinematic viscosity at 100 ° C. of less than 12.5 mm ² / s and a high temperature high shear viscosity (HTHS viscosity) at 150 ° C. of less than 3.5 mPa · s. . By setting it as such a viscosity range, it becomes possible to ensure lubricity in a supercharged direct injection engine or the like.
The kinematic viscosity at 100 ° C. of the lubricating oil composition, more preferably 6.1~12.5mm ² / s, further preferably 6.1~9.3mm ² / s. Furthermore, the HTHS viscosity at 150 ° C. is more preferably 1.7 to 3.2 mPa · s, and further preferably 2.0 to 2.9 mPa · s.

[Method for producing lubricating oil composition]
A method for producing a lubricating oil composition according to an embodiment of the present invention is a method for obtaining a lubricating oil composition by blending at least a metallic detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound with a lubricating base oil. Thus, the content of calcium atoms, the content of molybdenum atoms, and X calculated by the formula (1) are adjusted so as to be in the above-described predetermined range. In this production method, an ashless friction modifier may or may not be blended with the lubricating base oil. Further, boron-free succinimides and other additives may be blended. The details of these components, the blending amounts, and the like are the same as the details of the respective components described above and the contents of the respective components, and thus description thereof is omitted.
Further, as described above, the value of X approximates the value of the coefficient of friction between metals measured in the block-on-ring test. Therefore, when Formula (1) is used, it is possible to predict the friction coefficient of the resulting lubricating oil composition by the formulation of the lubricating oil composition without actually manufacturing the lubricating oil composition. Therefore, it is also possible to calculate the value of X in advance using Equation (1), determine the prescription of the lubricating oil composition so that the value of X falls within the predetermined range, and then manufacture the lubricating oil composition. It is.

[Use of lubricating oil composition]
The lubricating oil composition can be used for various types of lubricating oil, but is preferably used for lubrication in an internal combustion engine, more preferably used for a gasoline engine, and in particular, a direct injection mechanism and a supercharging mechanism are mounted. This is suitable for a supercharged direct injection engine. The lubricating oil composition can be used for such applications, and can exhibit excellent cleanliness and fuel saving performance while preventing low-speed pre-ignition.

[Method for reducing friction of internal combustion engine]
A friction reducing method for an internal combustion engine according to an embodiment of the present invention is to reduce the friction generated on the sliding surface of the internal combustion engine by adding the above-described lubricating oil composition to the internal combustion engine. The sliding surface is preferably a metal surface-metal surface.
According to the friction reducing method for an internal combustion engine of the present embodiment, by adjusting the X calculated by the formula (1) to the above predetermined range while keeping the calcium atom and the molybdenum atom in the lubricating oil composition constant. In addition, while ensuring excellent cleanliness, it is possible to achieve excellent fuel efficiency by improving the friction reduction effect. Moreover, it is suitable when the internal combustion engine is a gasoline engine, and particularly when it is a supercharged direct injection engine, it is possible to prevent low-speed pre-ignition.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

The measurement methods and evaluation methods for various properties in this specification are as follows.
(1) Kinematic viscosity It is a value measured using a glass capillary viscometer according to JIS K2283: 2000.
(2) Viscosity index This is a value measured according to JIS K 2283: 2000.
(3) HTHS viscosity at 150 ° C. Using a TBS viscometer (Tapered Bearing Simulator Viscometer) according to the method of ASTM D4683, shear rate 10 ⁶ sec ⁻¹ , rotation speed (motor) 3000 rpm, rotor / stator interval 3 μm, oil temperature 150 It was measured under the condition of ° C.
(4) Paraffin content by ring analysis (% Cp)
The ratio (percentage) of the paraffin calculated by the ring analysis ndM method is shown and measured according to ASTM D-3238.
(5) Soap content Rubber membrane dialysis was performed on the calcium-based detergent, and the rubber membrane residue after dialysis was treated with hydrochloric acid, and then the components extracted with diethyl ether were quantified as soap content.
(6) Measuring method of content of calcium atom, magnesium atom, phosphorus atom, molybdenum atom, boron atom It measured based on JPI-5S-38-92.
(7) Base number The base number of the lubricating oil composition was measured according to the perchloric acid method of JIS K2501: 2003. The base number of the metallic detergent is measured according to the perchloric acid method of JIS K2501: 2003.
(8) Friction coefficient (LFW-1 test)
The friction coefficient between metals was measured using the block on-ring test machine (LFW-1). Specific test conditions are as follows.
・ Test equipment:
Ring: S-10 standard material Block: SUJ-2
·Test conditions:
Oil temperature: 80 ° C
Load: 30kgf
Rotation speed: 160rpm
(9) Hot tube test It was performed based on JPI-5S-55-99. Specifically, the lubricating oil composition was continuously supplied at 0.3 ml / hour and air at 10 ml / minute for 16 hours in a glass tube having an inner diameter of 2 mm maintained at a temperature of 280 ° C. The lacquer adhering in the glass tube was compared with the color sample, and the score was given as 10 points for transparent and 0 points for black. The higher the score, the higher the cleanliness.

[Examples 3 and 5 to 9, Reference Examples 1, 2, and 4, Comparative Examples 1 to 3]
According to the formulation shown in Table 1, lubricating oil compositions of Examples, Reference Examples and Comparative Examples were prepared. About the obtained lubricating oil composition, each property and content of each atom in a lubricating oil composition were measured. In addition, the friction coefficient was measured by the LFW-1 test, and a hot tube test was also performed. These results are shown in Table 1.
The blending amount of the viscosity index improver was adjusted so that the HTHS viscosity at 150 ° C. of the lubricating oil compositions of Examples , Reference Examples and Comparative Examples was 2.3 mPa · s.

In addition, the detail of each component in Table 1 is as follows.
Lubricating oil base oil: Kinematic viscosity (100 ° C.) 4.0 mm ² / s, viscosity index 130,% Cp: 87% by mass Mineral oil Calcium detergent 1: Calcium salicylate calcium detergent 2: Calcium sulfonate magnesium detergent Agent: Magnesium sulfonate, Base number: 410 mgKOH / g
Friction modifier: Molybdenum dialkyldithiocarbamate compound Ashless friction modifier: Glycerol monooleate viscosity index improver: Polymethacrylate pour point depressant with a weight average molecular weight of 300,000: Polymethacrylate additive with a weight average molecular weight of 50,000 Package A: Boron-based detergent dispersant, boron-free alkenyl succinimide, zinc dialkyldithiophosphate, phenol-based antioxidant, and amine-based antioxidant additive additive package B: Of additive package A, boron-based detergent dispersant Additive package C: Mixture of boron-free alkenyl succinimide, zinc dialkyldithiophosphate, phenolic antioxidant, and amine antioxidant

As is apparent from the results in Table 1, in Examples 3 and 5 to 9 , the lubricating oil composition contains a metal detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound, and the amount of calcium atoms in the composition. In addition, by setting the value of X to less than 0.050 while keeping the molybdenum atomic weight within a predetermined range, it was possible to reduce the value of the friction coefficient while maintaining cleanliness.
On the other hand, in Comparative Examples 1 and 2, the lubricating oil composition contains a metal detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound, and the calcium atomic weight and the molybdenum atomic weight in the composition are within a predetermined range. However, since the value of X was 0.050 or more, the coefficient of friction also increased, and a lubricating oil composition having good fuel economy could not be provided.
Further, as shown in Comparative Example 3, even when the value of X was less than 0.050, if the boron-containing compound was not contained, the score of the hot tube test was lowered, and sufficient cleanliness could not be obtained.

Claims (9)

A lubricating oil composition for use in a supercharged direct injection engine comprising a lubricating base oil, a metallic detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound and equipped with a direct injection mechanism and a supercharging mechanism. ,
The lubricating base oil has a kinematic viscosity at 100 ° C. of 3 to 5 mm ² / s, and a paraffin content (% Cp) by ndM ring analysis of 80% or more,
The metallic detergent is
Containing calcium salicylate and magnesium sulfonate, or calcium salicylate, calcium sulfonate, and magnesium sulfonate;
The lubricating oil composition optionally contains an ashless friction modifier,
In the lubricating oil composition, the content of calcium atoms is 0.12 to 0.16% by mass based on the total amount of the lubricating oil composition, and the content of molybdenum atoms is 0.05 to 0.5 based on the total amount of the lubricating oil composition. 0.10% by mass,
In the lubricating oil composition, when calcium sulfonate is used in combination with magnesium sulfonate as the metallic detergent, the magnesium atom content is 0.02 to 0.06% by mass based on the total amount of the lubricating oil composition, and the metal When calcium sulfonate is not used in combination with magnesium sulfonate as a system detergent, the content of magnesium atoms is 0.04 to 0.08 mass% based on the total amount of the lubricating oil composition,
The boron atom content of the boron-containing compound in the lubricating oil composition is 0.3 or more with respect to the molybdenum atom content in the lubricating oil composition,
And the lubricating oil composition whose X computed by following formula (1) is less than 0.050.
X = 3.8 × 10 ⁻² −2.7 × 10 ⁻⁴ × [A] −4.2 × 10 ⁻¹ × [B] + 5.4 × 10 ⁻¹ × [C] −5.2 × 10 ⁻³ × [D] + 7.3 × 10 ⁻³ × [E] (1)
(In the above formula (1),
[A] is a proportion (mass%) of the soap derived from calcium sulfonate out of the total mass of soap derived from calcium salicylate, calcium sulfonate and calcium phenate,
[B] is a magnesium atom content (mass%) of magnesium sulfonate,
[C] is the content (% by mass) of boron atoms contained in the lubricating oil composition,
[D] is the content (mass%) of the ashless friction modifier,
[E] is E calculated by the following equation (2).
E = ([A] +1) × ([B] +0.001) (2)
Represents. The values [B] to [D] are values based on the total amount of the lubricating oil composition. )   The lubricating oil composition according to claim 1, wherein the total content of calcium atoms and magnesium atoms in the lubricating oil composition is 0.3 mass% or less based on the total amount of the lubricating oil composition. The boron-containing compound, a borated dispersant, an alkali metal borates, boric oxide epoxide, boric acid ester, according to claim 1 or 2 is at least one selected from borated fatty amines, and the group consisting of borated amide lubricating oil composition according to. The lubricating oil composition according to any one of claims 1 to 3 , further comprising a boron-free succinimide. The lubricating oil according to any one of claims 1 to 4 , wherein the ashless friction modifier is at least one selected from the group consisting of an ester ashless friction modifier and an amine ashless friction modifier. Composition. Further, viscosity index improvers, pour point depressants, antiwear agents, antioxidants, and one or more lubricating oil additives selected from the group consisting of antifoaming agents, claim 1-5 2. The lubricating oil composition according to item 1. Kinematic viscosity at 100 ° C. of less than 12.5 mm ² / s, and the high temperature high shear viscosity at 0.99 ° C. (HTHS viscosity) is less than 3.5 mPa · s, in any one of claims 1 to 6 The lubricating oil composition described. The lubricating oil composition according to any one of claims 1 to 7 , wherein the base number is 4 to 10 mgKOH / g. A lubricating oil composition used for a supercharged direct injection engine in which at least a metallic detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound are blended with a lubricating base oil and a direct injection mechanism and a supercharging mechanism are mounted. A method for producing a lubricating oil composition, comprising:
The lubricating base oil has a kinematic viscosity at 100 ° C. of 3 to 5 mm ² / s, and a paraffin content (% Cp) by ndM ring analysis of 80% or more,
The metallic detergent is
Containing calcium salicylate and magnesium sulfonate, or calcium salicylate, calcium sulfonate, and magnesium sulfonate;
The lubricant base oil may optionally contain an ashless friction modifier,
In the lubricating oil composition, the content of calcium atoms is 0.12 to 0.16% by mass based on the total amount of the lubricating oil composition, and the content of molybdenum atoms is 0.05 to 0.5 based on the total amount of the lubricating oil composition. 0.10% by mass,
In the lubricating oil composition, when calcium sulfonate is used in combination with magnesium sulfonate as the metallic detergent, the magnesium atom content is 0.02 to 0.06% by mass based on the total amount of the lubricating oil composition, and the metal When calcium sulfonate is not used in combination with magnesium sulfonate as a system detergent, the content of magnesium atoms is 0.04 to 0.08 mass% based on the total amount of the lubricating oil composition,
The boron atom content of the boron-containing compound in the lubricating oil composition is 0.3 or more with respect to the molybdenum atom content in the lubricating oil composition,
And the manufacturing method of the lubricating oil composition adjusted so that X computed by following formula (1) might be less than 0.050.
X = 3.8 × 10 ⁻² −2.7 × 10 ⁻⁴ × [A] −4.2 × 10 ⁻¹ × [B] + 5.4 × 10 ⁻¹ × [C] −5.2 × 10 ⁻³ × [D] + 7.3 × 10 ⁻³ × [E] (1)
(In the above formula (1),
[A] is a proportion (mass%) of the soap derived from calcium sulfonate out of the total mass of soap derived from calcium salicylate, calcium sulfonate and calcium phenate,
[B] is a magnesium atom content (mass%) of magnesium sulfonate,
[C] is the content (% by mass) of boron atoms contained in the lubricating oil composition,
[D] is the content (mass%) of the ashless friction modifier,
[E] is E calculated by the following equation (2).
E = ([A] +1) × ([B] +0.001) (2)
Represents. [B] to [D] are values based on the total amount of the lubricating oil composition. )