JP6730123B2 - Lubricating oil composition - Google Patents

Description

The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition for internal combustion engines, especially for gasoline engines.

Lubricating oil compositions are widely used in the automobile field such as for internal combustion engines, automatic transmissions, and gear oils. In recent years, there has been a demand for lowering the viscosity in order to improve fuel efficiency, but the oil film becomes thin due to the lowering of the viscosity, and it is not possible to sufficiently reduce friction. Therefore, molybdenum dithiocarbamate (MoDTC), which can reduce friction by generating molybdenum disulfide under boundary lubrication conditions, has been conventionally used. At this time, it is usual to use a calcium-based detergent in combination (for example, Patent Document 1). However, with this combination, there is a limit to the reduction of friction, and fuel efficiency cannot be sufficiently improved.

It is also known to use a magnesium-based detergent as a detergent (for example, Patent Documents 2 and 3). The use of the magnesium-based detergent can reduce friction more than the calcium-based detergent, but has a problem that abrasion is likely to occur.

JP, 2013-199594, A JP, 2011-184566, A JP, 2006-328265, A

It is an object of the present invention to provide a lubricating oil composition capable of reducing friction while ensuring antiwear properties even when the viscosity is reduced, and as a preferred embodiment, a lubricating oil composition used in an internal combustion engine, and more preferably Is to provide a lubricating oil composition for use in a supercharged gasoline engine.

As a result of diligent studies, the present inventors have found that by adding a specific amount of one or more metal salicylates selected from calcium salicylate and magnesium salicylate and a specific amount of molybdenum friction modifier to a lubricating base oil. , It has been found that the above object is achieved.

That is, the present invention is
A lubricating oil composition comprising a lubricating base oil, (A1) a metal-based salicylate, and (B) a molybdenum-based friction modifier,
The amount of component (B) is in the range of 500 to 1500 mass ppm as the concentration [B] based on mass ppm of molybdenum in the lubricating oil composition,
The component (A1) is either calcium salicylate, magnesium salicylate, or a combination thereof, and the amount of the calcium salicylate is 0 to 0 as a concentration [Ca] in terms of mass ppm of calcium derived from the calcium salicylate in the lubricating oil composition. 1800 mass ppm, the amount of the magnesium salicylate is 0 to 1800 mass ppm as the concentration [Mg] based on the mass ppm of magnesium derived from the magnesium salicylate in the lubricating oil composition, and the [Ca] and [ Mg] is in the range of 200 to 3000 mass ppm in total, which is a lubricating oil composition.

In a preferred embodiment of the present invention, the lubricating oil composition further has at least one of the following features (1) to (10).
(1) A lubricating oil composition containing (A) a metal-based detergent, wherein (A1) a metal-based salicylate is added to a metal derived from the metal-based detergent in the lubricating oil composition based on the total mass of the (A) component. The lubricating oil composition is characterized in that the content of [Ca] and [Mg] with respect to the concentration [A] based on the total mass ppm is 5 to 100 mass %.
(2) The lubricating oil composition may further contain a metal-based detergent other than the component (A1) as the (A) metal-based detergent, and the component (A1) with respect to the total mass of the (A) metal-based detergent. Is in the range of 5 to 100% by mass.
(3) (A1) The metal salicylate is magnesium salicylate and calcium salicylate.
(4) The (A1) metal salicylate is at least one magnesium salicylate.
(5) The lubricating oil composition further contains (A) a metal-based detergent (A2) other than the component (A1) as the metal-based detergent, and the (A2) component is at least one selected from magnesium, calcium and sodium. Including the seed, the total content of the (A) metallic detergent is represented by the formula (1):
[A]/[B]≦4.5 (1)
([A] is the concentration of total mass ppm of magnesium, calcium and sodium in the lubricating oil composition)
Meet
(6) The content of the metal salicylate (A1) is represented by the following formula (2):
[A1]/[B]<4.5 (2)
([A1] satisfies the concentration of the total mass ppm of magnesium and calcium derived from the component (A1) in the lubricating oil composition (the above [Ca]+the above [Mg])).
(7) The CCS viscosity at −35° C. is 6.2 Pa·s or less.
(8) The high temperature high shear viscosity (HTHS viscosity) at 150° C. is 1.7 to 2.9 mPa·s.
(9) The kinematic viscosity at 100° C. is less than 9.3 mm ² /s.
(10) For internal combustion engines.
Furthermore, the present invention relates to a method for reducing friction while maintaining low wearability by using the lubricating oil composition or the lubricating oil composition according to the embodiments (1) to (10).

INDUSTRIAL APPLICABILITY The lubricating oil composition of the present invention can reduce friction while ensuring antiwear properties even when the viscosity is lowered, and in particular, it is used for internal combustion engine lubricating oils and supercharged gasoline engines. It can be suitably used as an oil composition.

Lubricating base oil The lubricating base oil in the present invention is not particularly limited. Either mineral oil or synthetic oil may be used, and these may be used alone or in combination.

Examples of the mineral oil include, for example, a lubricating oil fraction obtained by distilling a crude oil under atmospheric pressure and distilling under atmospheric pressure under reduced pressure, solvent degassing, solvent extraction, hydrocracking, solvent dewaxing, and hydrogen. Refined by one or more treatments such as chemical refining, wax isomerized mineral oil, GTL (gas to liquid) base oil, ATL (asphalt to liquid) base oil, vegetable oil base oil or a mixture thereof Base oils may be mentioned.

Examples of the synthetic oil include polybutene or a hydrogenated product thereof; poly-α-olefin such as 1-octene oligomer, 1-decene oligomer or a hydrogenated product thereof; 2-ethylhexyl laurate, 2-ethylhexyl palmitate, 2-stearic acid. Monoesters such as ethylhexyl; diesters such as ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate; neopentyl glycol di-2-ethylhexanoate, neopentyl Glycol di-n-octanoate, neopentyl glycol di-n-decanoate, trimethylolpropane tri-n-octanoate, trimethylolpropane tri-n-decanoate, pentaerythritol tetra-n-pentanoate, pentaerythritol tetra-n-hexanoate, Examples thereof include polyol esters such as pentaerythritol tetra-2-ethylhexanoate; aromatic synthetic oils such as alkylnaphthalene, alkylbenzene and aromatic esters, and mixtures thereof.

The kinematic viscosity (mm ² /s) at 100° C. of the lubricating base oil is not particularly limited, but it is preferably ² to 15 mm ² /s, more preferably 3 to 10 mm ² /s, and further preferably 3 to. It is 8 mm ² /s, most preferably 3 to 6 mm ² /s. This makes it possible to obtain a lubricating oil composition in which oil film formation is sufficient, lubricity is excellent, and evaporation loss is small.

The viscosity index (VI) of the lubricating base oil is not particularly limited, but it is preferably 100 or more, more preferably 120 or more, and most preferably 130 or more. This makes it possible to reduce the viscosity at low temperatures while ensuring an oil film at high temperatures.

(A) Metallic Detergent (A1) Metallic Salicylate The lubricating oil composition of the present invention comprises (A) a metal detergent, (A1) a metal salicylate, calcium salicylate, magnesium salicylate, or a combination thereof. It is characterized by including in a specific range amount described below. The lubricating oil composition of the present invention may further contain (A) a metal-based detergent other than calcium salicylate and magnesium salicylate as the metal-based detergent, but (A1) with respect to the total mass of the (A) metal-based detergent. [Ca] and [Mg] ([Ca] is derived from calcium salicylate in the lubricating oil composition) relative to the concentration [A] based on the total mass ppm of the metal derived from the metal-based detergent in the lubricating oil composition. The concentration of calcium by mass ppm, [Mg] is 5 to 100% by mass, preferably 10 to 100% by mass, as the ratio of the concentration by mass ppm of magnesium derived from magnesium salicylate in the lubricating oil composition). It is preferably 15 to 100% by mass, particularly preferably 20 to 100% by mass, and most preferably 50 to 100% by mass. By containing at least one selected from calcium salicylate and magnesium salicylate in a specific amount as the metal-based detergent, it is possible to secure high-temperature detergency and rust preventive properties required as a lubricating oil. Also, friction can be reduced and therefore torque can be reduced. This is particularly advantageous in terms of fuel consumption characteristics.

The amount of the component (A1) in the lubricating oil composition of the present invention is such that the amount of the calcium salicylate is 0 to 1800 mass ppm, preferably 0 to 1600 mass as the concentration [Ca] based on the mass ppm of calcium in the lubricating oil composition. ppm, the amount of the magnesium salicylate is 0 to 1800 mass ppm, preferably 0 to 1600 mass ppm as the concentration [Mg] based on the mass ppm of magnesium in the lubricating oil composition, and the above [Ca]+[ Mg] is in the range of 200 to 3000 mass ppm, preferably 300 to 2500 mass ppm, and more preferably 400 to 2000 mass ppm. If the amount of the component (A1) exceeds the above upper limit, wear may become excessive or sludge may come out, and if it is less than the above lower limit, the effect of reducing friction is low.

As described above, the present invention essentially requires at least one selected from magnesium salicylate and calcium salicylate as the metal salicylate. Only one of these may be used, or two or more may be used in combination. Preferred is a combination of magnesium salicylate and calcium salicylate, or magnesium salicylate alone, and more preferred is magnesium salicylate.

When the component (A1) is only magnesium salicylate, the content thereof is such that the concentration [Mg] of magnesium derived from magnesium salicylate in the lubricating oil composition is 200 to 1800 mass ppm, preferably 250 to 1500 mass ppm. , More preferably 300 to 1200 mass ppm, and most preferably 400 to 1000 ppm. When the component (A1) is only calcium salicylate, the content thereof is such that the concentration [Ca] by mass ppm of calcium derived from calcium salicylate in the lubricating oil composition is 200 to 1800 mass ppm, preferably 300 to 1600 mass ppm. , And more preferably in an amount of 500 to 1400 mass ppm. When the component (A1) is a combination of magnesium salicylate and calcium salicylate, the total of [Ca] and [Mg] is 200 to 3000 mass ppm, preferably 300 to 2500 mass ppm, more preferably 400 to 2000 mass ppm. The range of should be satisfied. Particularly, [Mg] is in the range of 100 to 1600 mass ppm, preferably 150 to 1400 mass ppm, more preferably 200 to 1200 mass ppm, most preferably 300 to 1000 ppm, and [Ca] is 100 to 1600. Mass ppm, preferably 300 to 1500 mass ppm, more preferably 500 to 1400 mass ppm.

The magnesium content in magnesium salicylate and the calcium content in calcium salicylate are preferably 0.5 to 20% by mass, more preferably 1 to 16% by mass, and most preferably 2 to 14% by mass. .. The blending amount of the component (A1) is adjusted so that the lubricating oil composition contains magnesium and calcium within the above-described range.

The (A1) metal-based salicylate is particularly preferably an overbased metal-based salicylate, preferably magnesium salicylate and calcium salicylate, and particularly preferably overbased magnesium salicylate. Thereby, the acid neutralization property required for the lubricating oil can be secured. If overbased magnesium salicylate is used, neutral magnesium or calcium based detergents may be mixed. When using an overbased calcium salicylate, you may use together a neutral calcium type detergent.

The total base number of the (A1) metal salicylate is not limited, but is preferably 20 to 600 mgKOH/g, more preferably 50 to 500 mgKOH/g, and most preferably 100 to 450 mgKOH/g. As a result, it is possible to secure the acid neutralization property, high temperature detergency property and rust prevention property required for the lubricating oil. When two or more kinds of metal salicylates are mixed and used, the base number obtained by mixing is preferably within the above range.

The amount of component (A1) in the lubricating oil composition is preferably an amount that satisfies the following formula (2).
[A1]/[B]<4.5 (2)
In the formula (2), [A1] is the concentration of the total mass ppm of magnesium and calcium derived from (A1) magnesium salicylate and calcium salicylate in the lubricating oil composition (that is, [Ca]+[Mg] described above). Indicates. [B] is as described above.
The value of [A1]/[B] is preferably less than 3.0, more preferably less than 2, even more preferably less than 1.8, particularly preferably less than 1.5. If the value exceeds the upper limit, the torque reduction effect may be low. The lower limit of [A1]/[B] is preferably 0.1, more preferably 0.2, and further preferably 0.3.

A preferred embodiment of the lubricating oil composition of the present invention is, as described above, an embodiment containing only magnesium salicylate as the (A1) metal salicylate or an embodiment containing a combination of magnesium salicylate and calcium salicylate as the (A1) component. The lubricating oil composition of the present invention may further contain (A1) a metal-based detergent (A2) other than calcium salicylate and magnesium salicylate as the (A) metal-based detergent. In this case, as described above, the mass ratio of the component (A1) to the total mass of the metal detergent (A) is based on the concentration [A] of the total mass ppm of the metal derived from the metal detergent in the lubricating oil composition. The ratio of [Ca] and [Mg] is 5 to 100% by mass, preferably 10 to 100% by mass, more preferably 15 to 100% by mass, particularly preferably 20 to 100% by mass, and most preferably 50. ˜100% by mass is preferred. In particular, the mass% of magnesium salicylate based on the total mass of the (A) metal-based detergent is defined as the ratio of [Mg] to the concentration [A] based on the total mass ppm of the metal derived from the metal-based detergent in the lubricating oil composition. 5 to 100% by mass, preferably 10 to 80% by mass, more preferably 10 to 60% by mass, and particularly preferably 10 to 40% by mass. A more preferred embodiment is a mode in which the metal detergent (A) contains only magnesium salicylate or only a combination of magnesium salicylate and calcium salicylate.

(A2) Metal-based detergent other than the above metal-based salicylates
The lubricating oil composition of the present invention can be used in combination with a conventionally known metallic detergent containing at least one selected from magnesium, calcium and sodium as the metallic detergent (A2) component other than (A1) metallic salicylate. .. Examples of the component (A2) include metal sulfonates. The metal sulfonate may be one kind or a combination of two or more kinds. By containing the metal-based sulfonate, it is possible to further secure high-temperature detergency and rust resistance required as a lubricating oil. Although the amount of the component (A2) depends on the amount of the component (A1), the concentration [A2] of the metal derived from the component (A2) in the lubricating oil composition is preferably 0 to 5000 mass ppm, and more preferably Is 0 to 2000 mass ppm, most preferably 0 to 1000 mass ppm.

Examples of metal-based sulfonates include magnesium sulfonate, calcium sulfonate, and sodium sulfonate.

In addition, conventional metal-based detergents other than the above can be used within a range that does not impair the effects of the present invention. For example, it may contain magnesium phenate, calcium phenate, and a sodium detergent. Preferred sodium detergents are sodium sulfonate, sodium phenate and sodium salicylate. These sodium detergents may be used alone or in combination of two or more. By including the sodium-based detergent, it is possible to secure high-temperature detergency and rustproofness required as a lubricating oil. The sodium-based detergent can be used in combination with the magnesium-based detergent and the optional calcium-based detergent described above.

Preferably, the total amount of the metal-based detergent (A) in the lubricating oil composition satisfies the following formula (1).
[A]/[B]≦4.5 (1)
In the formula (1), [A] indicates the concentration of magnesium, calcium and sodium in the lubricating oil composition based on the total mass ppm, and [B] indicates the concentration of molybdenum in the lubricating oil composition based on the mass ppm.
The value of [A]/[B] is preferably 3.0 or less, more preferably 2.8 or less, still more preferably 2.6 or less, still more preferably 2.5 or less. If the above value exceeds the above upper limit, the wear may become excessive. The lower limit of [A]/[B] is preferably 0.2, more preferably 0.5, and further preferably 1.

(B) Molybdenum-based friction modifier The molybdenum-based friction modifier is not particularly limited, and conventionally known ones can be used. For example, sulfur-containing organic molybdenum compounds such as molybdenum dithiophosphate (MoDTP) and molybdenum dithiocarbamate (MoDTC), complexes of molybdenum compounds with sulfur-containing organic compounds or other organic compounds, and molybdenum sulfide and molybdenum sulfide. Examples thereof include a complex of a sulfur-containing molybdenum compound and an alkenylsuccinimide. Examples of the molybdenum compound include molybdenum oxide such as molybdenum dioxide and molybdenum trioxide, molybdic acid such as ortho-molybdic acid, para-molybdic acid and (poly)sulfurized molybdic acid, and molybdenum such as metal salts and ammonium salts of these molybdic acids. Examples thereof include acid salts, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, polymolybdenum sulfide and the like, molybdenum sulfide, molybdenum sulfide, metal salts or amine salts of molybdenum sulfide, 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, and organic (poly)sulfide. And sulfurized esters. In particular, organic molybdenum compounds such as molybdenum dithiophosphate (MoDTP) and molybdenum dithiocarbamate (MoDTC) are preferable.

Molybdenum dithiocarbamate (MoDTC) is a compound represented by the following formula [I], and molybdenum dithiophosphate (MoDTP) is a compound represented by the following [II].

In the general formulas [I] and [II], R _{1 to} R ₈ may be the same or different from each other and are a monovalent hydrocarbon group having 1 to 30 carbon atoms. The hydrocarbon group may be linear or branched. As the monovalent hydrocarbon group, a linear or branched alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; a cycloalkyl group having 4 to 30 carbon atoms; an aryl having 6 to 30 carbon atoms Group, an alkylaryl group, an arylalkyl group, and the like. In the arylalkyl group, the bonding position of the alkyl group is arbitrary. More specifically, as the alkyl group, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group. , A tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, and the like, and branched alkyl groups thereof, and an alkyl group having 3 to 8 carbon atoms is particularly preferable. Further, X ₁ and X ₂ are oxygen atoms or sulfur atoms, and Y ₁ and Y ₂ are oxygen atoms or sulfur atoms.

As the component (B), an organic molybdenum compound containing no sulfur can also be used. Examples of such a compound include a molybdenum-amine complex, a molybdenum-succinimide complex, a molybdenum salt of an organic acid, and a molybdenum salt of an alcohol.

Furthermore, the trinuclear molybdenum compound described in US Pat. No. 5,906,968 can be used as the friction modifier (B) in the present invention.

The component (B) is added in an amount such that the concentration [B] of the molybdenum in the lubricating oil composition as mass ppm is in the range of 500 to 1500 mass ppm, preferably 600 to 1200 mass ppm. If the amount of the component (B) exceeds the above upper limit, the cleanability may deteriorate, and if it is less than the above lower limit, the friction may not be sufficiently reduced or the cleanability may deteriorate. is there.

As described above for the component (A), the amount of the component (B) is preferably the following formula (1):
[A]/[B]≦4.5 (1)
Meet In the formula (1), [A] indicates the concentration of magnesium, calcium and sodium in the lubricating oil composition based on the total mass ppm, and [B] indicates the concentration of molybdenum in the lubricating oil composition based on the mass ppm.
The value of [A]/[B] is preferably 3.0 or less, more preferably 2.8 or less, still more preferably 2.6 or less, still more preferably 2.5 or less. The lower limit of [A]/[B] is preferably 0.2, more preferably 0.5, and even more preferably 1.0.

As described above for the component (A1), the amount of the component (B) is preferably the following formula (2):
[A1]/[B]<4.5 (2)
Meet Here, [A1] represents the concentration in mass ppm of the metal derived from the component (A1) in the lubricating oil composition. The value of [A1]/[B] is preferably less than 3.0, more preferably less than 2.0, further preferably less than 1.8, particularly preferably less than 1.5. If the value exceeds the upper limit, the torque reduction effect may be low. The lower limit of [A1]/[B] is preferably 0.1, more preferably 0.2, and further preferably 0.3.

The lubricating oil composition of the present invention essentially comprises the above-mentioned lubricating base oil, the component (A1) and the component (B), but as an optional component, a conventionally known antiwear agent, ashless dispersant and viscosity index improver. May be included.

As the antiwear agent, a conventionally known one can be used. Among them, antiwear agents containing phosphorus are preferable, and zinc dithiophosphate (ZnDTP (also referred to as ZDDP)) represented by the following formula is particularly preferable.

上記式において、Ｒ^１及びＲ^２は、各々、互いに同一であっても異なっていてもよく、水素原子または炭素数１〜２６の一価炭化水素基である。一価炭化水素基としては、炭素数１〜２６の第１級（プライマリー）または第２級（セカンダリー）アルキル基；炭素数２〜２６のアルケニル基；炭素数６〜２６のシクロアルキル基；炭素数６〜２６のアリール基、アルキルアリール基またはアリールアルキル基；またはエステル結合、エーテル結合、アルコール基またはカルボキシル基を含む炭化水素基である。Ｒ^１及びＲ^２は、好ましくは炭素数２〜１２の、第１級または第２級アルキル基、炭素数８〜１８のシクロアルキル基、炭素数８〜１８のアルキルアリール基であり、各々、互いに同一であっても異なっていてもよい。特にはジアルキルジチオリン酸亜鉛が好ましく、第１級アルキル基は、炭素数３〜１２を有することが好ましく、より好ましくは炭素数４〜１０である。第２級アルキル基は、炭素数３〜１２を有することが好ましく、より好ましくは炭素数３〜１０である。上記ジチオリン酸亜鉛は１種を単独で使用してもよく、２種以上を混合して使用してもよい。また、ジチオカルバミン酸亜鉛（ＺｎＤＴＣ）を組合せて使用してもよい。

In the above formula, R ¹ and R ^{2, which} may be the same or different, are each a hydrogen atom or a monovalent hydrocarbon group having 1 to 26 carbon atoms. As the monovalent hydrocarbon group, a primary (primary) or secondary (secondary) alkyl group having 1 to 26 carbon atoms; an alkenyl group having 2 to 26 carbon atoms; a cycloalkyl group having 6 to 26 carbon atoms; carbon An aryl group, an alkylaryl group or an arylalkyl group of the formulas 6 to 26; or a hydrocarbon group containing an ester bond, an ether bond, an alcohol group or a carboxyl group. R ¹ and R ² are preferably a C 2-12 primary or secondary alkyl group, a C 8-18 cycloalkyl group, a C 8-18 alkylaryl group, and They may be the same as or different from each other. In particular, zinc dialkyldithiophosphate is preferable, and the primary alkyl group preferably has 3 to 12 carbon atoms, and more preferably 4 to 10 carbon atoms. The secondary alkyl group preferably has 3 to 12 carbon atoms, and more preferably 3 to 10 carbon atoms. The zinc dithiophosphates may be used alone or in combination of two or more. Further, zinc dithiocarbamate (ZnDTC) may be used in combination.

Further, it is also possible to use at least one compound selected from phosphates and phosphite-based phosphorus compounds represented by the following formulas (3) and (4), and metal salts and amine salts thereof.

上記一般式（３）中、Ｒ^３は炭素数１〜３０の一価炭化水素基であり、Ｒ^４及びＲ^５は互いに独立に、水素原子又は炭素数１〜３０の一価炭化水素基であり、ｍは０又は１である。

In the general formula (3), R ³ is a monovalent hydrocarbon group having 1 to 30 carbon atoms, and R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms. Yes, m is 0 or 1.

上記一般式（４）中、Ｒ^６は炭素数１〜３０の一価炭化水素基であり、Ｒ^７及びＲ^８は互いに独立に水素原子又は炭素数１〜３０の一価炭化水素基であり、ｎは０又は１である。

In the general formula (4), R ⁶ is a monovalent hydrocarbon group having 1 to 30 carbon atoms, and R ⁷ and R ⁸ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 30 carbon atoms. , N is 0 or 1.

In the general formulas (3) and (4), examples of the monovalent hydrocarbon group represented by R ^{3 to} R ⁸ having 1 to 30 carbon atoms include, for example, an alkyl group, a cycloalkyl group, an alkenyl group, and an alkyl-substituted cyclo group. Mention may be made of alkyl groups, aryl groups, alkyl-substituted aryl groups and arylalkyl groups. Particularly, it is preferably an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 24 carbon atoms, more preferably an alkyl group having 3 to 18 carbon atoms, and most preferably an alkyl group having 4 to 15 carbon atoms. Is.

Examples of the phosphorus compound represented by the above general formula (3) include, for example, phosphite monoester and (hydrocarbyl)phosphonous acid having one hydrocarbon group having 1 to 30 carbon atoms; and 1 to 30 carbon atoms. A phosphite diester having two hydrocarbon groups, a monothiophosphite diester, and a (hydrocarbyl)phosphonous acid monoester; a phosphite triester having three hydrocarbon groups having 1 to 30 carbon atoms, and (Hydrocarbyl) phosphonous acid diester; and mixtures thereof.

The metal salt or amine salt of the phosphorus compound represented by the general formula (3) or (4) is obtained by adding a metal oxide, a metal hydroxide, a phosphorus compound represented by the general formula (3) or (4), A metal base such as a metal carbonate or a metal chloride, ammonia, a nitrogen compound such as an amine compound having only a hydrocarbon group having 1 to 30 carbon atoms or a hydrocarbon group having a hydroxyl group in the molecule, and the like, and remains. It can be obtained by neutralizing a part or all of acidic hydrogen. Examples of the metal in the metal base include alkali metals such as lithium, sodium, potassium and cesium, alkaline earth metals such as calcium, magnesium and barium, heavy metals such as zinc, copper, iron, lead, nickel, silver and manganese. (However, molybdenum is excluded) and the like. Among these, alkaline earth metals such as calcium and magnesium and zinc are preferable, and zinc is particularly preferable.

The antiwear agent is usually added to the lubricating oil composition in an amount of 0.1 to 5.0% by mass, preferably 0.2 to 3.0% by mass.

As the ashless dispersant, a nitrogen-containing compound having at least one linear or branched alkyl group or alkenyl group having 40 to 500 carbon atoms, preferably 60 to 350 in a molecule, or a derivative thereof, a Mannich dispersant Or a mono- or bissuccinimide (for example, an alkenylsuccinimide), a benzylamine having at least one alkyl group or alkenyl group having 40 to 500 carbon atoms in the molecule, or an alkyl group or alkenyl group having 40 to 400 carbon atoms Examples thereof include polyamines having at least one in the molecule, or modified products thereof with boron compounds, carboxylic acids, phosphoric acids and the like. One kind or two or more kinds arbitrarily selected from these can be blended. In particular, it is preferable to contain alkenyl succinimide.

The method for producing the succinimide is not particularly limited, and for example, an alkyl succinic acid or an alkenyl succinic acid obtained by reacting a compound having an alkyl group or an alkenyl group having 40 to 500 carbon atoms with maleic anhydride at 100 to 200°C. Obtained by reacting an acid with a polyamine. Here, examples of the polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine. Examples of the derivative of the nitrogen-containing compound exemplified as the ashless dispersant include, for example, monocarboxylic acids such as fatty acids having 1 to 30 carbon atoms in the above-mentioned nitrogen-containing compound, oxalic acid, phthalic acid, trimellitic acid, and pyromellitic acid. A polycarboxylic acid having 2 to 30 carbon atoms such as an acid, or an anhydride thereof, or an ester compound, an alkylene oxide having 2 to 6 carbon atoms, or a hydroxy (poly)oxyalkylene carbonate is allowed to act to leave a residual amino group and/or A compound modified by a so-called oxygen-containing organic compound in which a part or all of the imino group is neutralized or amidated; one of the remaining amino group and/or imino group by reacting boric acid with the above-mentioned nitrogen-containing compound A part or all of which is neutralized or amidated, a so-called boron-modified compound; phosphoric acid acts on the above-mentioned nitrogen-containing compound to neutralize a part or all of the remaining amino group and/or imino group An amidated so-called phosphoric acid-modified compound; a sulfur-modified compound obtained by reacting a sulfur compound with the aforementioned nitrogen-containing compound; and a modification of the aforementioned nitrogen-containing compound with an oxygen-containing organic compound, boron modification, phosphoric acid modification, sulfur modification Examples of the modified compound include a combination of two or more modifications selected from Among these derivatives, the boric acid-modified compound of alkenyl succinimide, especially the boric acid-modified compound of bis-type alkenyl succinimide can further improve the heat resistance when used in combination with the above-mentioned base oil.

The amount of the ashless dispersant is 20% by mass or less, preferably 15% by mass or less, and more preferably 5% by mass or less, based on the total amount of the composition. Further, as the ashless dispersant, a boron-containing ashless dispersant may be mixed with an ashless dispersant containing no boron. When using a boron-containing ashless dispersant, the content ratio is not particularly limited, the amount of boron contained in the composition is the total amount of the composition, preferably 0.001 to 0.2 mass%, It is more preferably 0.003 to 0.1% by mass, and most preferably 0.005 to 0.05% by mass.

The number average molecular weight (Mn) of the ashless dispersant is preferably 2000 or more, more preferably 2500 or more, even more preferably 3000 or more, most preferably 5000 or more, and preferably 15000 or less. .. When the number average molecular weight of the ashless dispersant is less than the above lower limit value, the dispersibility may be insufficient. On the other hand, when the number average molecular weight of the ashless dispersant exceeds the above upper limit, the viscosity becomes too high and the fluidity becomes insufficient, which causes an increase in deposit.

Examples of the viscosity index improver include polymethacrylate, dispersion type polymethacrylate, olefin copolymer (polyisobutylene, ethylene-propylene copolymer), dispersion type olefin copolymer, polyalkylstyrene, styrene-butadiene hydrogenated copolymer. , Styrene-maleic anhydride copolymer, star-shaped isoprene, and the like. Furthermore, a comb polymer containing at least a repeating unit based on a polyolefin macromer and a repeating unit based on an alkyl (meth)acrylate having an alkyl group having 1 to 30 carbon atoms can be used.

Viscosity index improvers usually consist of the above polymers and diluent oil. The content of the viscosity index improver is preferably 0.01 to 20% by mass, more preferably 0.02 to 10% by mass, and most preferably 0.05 to 5% by mass as a polymer amount based on the total amount of the composition. %. When the content of the viscosity index improver is less than the above lower limit value, the viscosity temperature characteristic and the low temperature viscosity characteristic may be deteriorated. On the other hand, if the amount exceeds the above upper limit, the viscosity-temperature characteristic and the low-temperature viscosity characteristic may be deteriorated, and further, the product cost is significantly increased.

The lubricating oil composition of the present invention may further contain other additives depending on the purpose in order to improve its performance. As the other additives, those generally used in lubricating oil compositions can be used. For example, antioxidants, friction modifiers other than the above-mentioned component (B), corrosion inhibitors, rust preventives, flow agents Examples thereof include additives such as point depressants, demulsifiers, metal deactivators and defoamers.

Examples of the antioxidant include ashless antioxidants such as phenol-based and amine-based antioxidants, and metal-based antioxidants such as copper-based and molybdenum-based antioxidants. For example, phenol-based ashless antioxidants include 4,4′-methylenebis(2,6-di-tert-butylphenol), 4,4′-bis(2,6-di-tert-butylphenol), isooctyl- 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and the like, and amine-based ashless antioxidants include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, dialkyldiphenylamine and the like. To be The antioxidant is usually added to the lubricating oil composition in an amount of 0.1 to 5% by mass.

Examples of the friction modifier other than the component (B) include esters, amines, amides, and sulfurized esters. The friction modifier is usually added to the lubricating oil composition in an amount of 0.01 to 3% by mass.

Examples of the corrosion inhibitor include benzotriazole-based, tolyltriazole-based, thiadiazole-based and imidazole-based compounds. Examples of the rust preventive agent include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester. The rust preventive agent and the corrosion inhibitor are usually blended in the lubricating oil composition in an amount of 0.01 to 5% by mass, respectively.

As the pour point depressant, for example, a polymethacrylate polymer compatible with the lubricating base oil used can be used. The pour point depressant is usually arranged in the lubricating oil composition in an amount of 0.01 to 3% by mass.

Examples of the demulsifiers include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and polyoxyethylene alkylnaphthyl ether. The demulsifier is usually blended in the lubricating oil composition in an amount of 0.01 to 5% by mass.

Examples of the metal deactivator include imidazoline, pyrimidine derivative, alkylthiadiazole, mercaptobenzothiazole, benzotriazole or a derivative thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5- Examples thereof include bisdialkyldithiocarbamate, 2-(alkyldithio)benzimidazole and β-(o-carboxybenzylthio)propionnitrile. The metal deactivator is usually blended in the lubricating oil composition in an amount of 0.01 to 3% by mass.

Examples of the defoaming agent include silicone oil having a kinematic viscosity at 25° C. of 1000 to 100,000 mm ² /s, alkenyl succinic acid derivative, ester of polyhydroxy aliphatic alcohol and long chain fatty acid, methyl salicylate and o. -Hydroxybenzyl alcohol and the like can be mentioned. The antifoaming agent is usually added to the lubricating oil composition in an amount of 0.001 to 1% by mass.

As another additive, an alkaline borate additive can be added. The alkaline borate-based additive contains an alkali metal borate hydrate and can be represented by the following general formula.
M ₂ O・xB ₂ O ₃・yH ₂ O
In the above formula, M is an alkali metal, x is 2.5 to 4.5, and y is 1.0 to 4.8.
Specific examples thereof include lithium borate hydrate, sodium borate hydrate, potassium borate hydrate, rubidium borate hydrate and cesium borate hydrate. Hydrates and sodium borate hydrates are preferable, and potassium borate hydrate is particularly preferable. The average particle size of the alkali metal borate hydrate particles is generally 1 micron (μ) or less. In the alkali metal borate hydrate used in the present invention, the ratio of boron to alkali metal is preferably in the range of about 2.5:1 to 4.5:1. The addition amount of the alkaline borate-based additive is 0.002 to 0.05 mass% as the amount of boron based on the total amount of the lubricating oil composition.

The CCS viscosity at −35° C. of the lubricating oil composition of the present invention is not limited, but is preferably 6.2 Pa·s or less, more preferably 5.0 Pa·s or less, still more preferably 4.0 Pa·s or less, most preferably It is preferably 3.5 Pa·s or less.

In the lubricating oil composition of the present invention, it is preferable that the amount of molybdenum contained in the lubricating oil composition and the CCS viscosity at −35° C. satisfy the following formula (5).
[CCS viscosity]/[B]≦0.01 (5)
([CCS viscosity] indicates the CCS viscosity value (Pa·s) of the lubricating oil composition at −35° C., and [B] indicates the concentration of molybdenum in the lubricating oil composition in terms of mass ppm.)
The value of [CCS viscosity]/[B] is more preferably 0.008 or less, still more preferably 0.005 or less. If the above value exceeds 0.01, the torque reduction rate may be reduced, or the cleanliness may be deteriorated. The lower limit value of [CCS viscosity]/[B] is not limited, but is preferably 0.002, more preferably 0.003.

Although the high temperature high shear viscosity (HTHS viscosity) at 150° C. of the lubricating oil composition of the present invention is not limited, it is preferably 1.7 to 2.9 mPa.s. s, more preferably 2.0 to 2.6 mPa.s. s.

The kinematic viscosity at 100° C. of the lubricating oil composition of the present invention is not limited, but it is preferably less than 9.3 mm ² /s, more preferably less than 8.2 mm ² /s.

INDUSTRIAL APPLICABILITY The lubricating oil composition of the present invention has an effect that it has sufficient friction characteristics and wear characteristics and has a high torque reduction rate even if it has a low viscosity. It can be preferably used for applications.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The materials used in the examples and comparative examples are as follows.
Lubricating base oil Lubricating base oil: Fischer-Tropsch derived base oil, kinematic viscosity at 100° C.=4.1 mm ² /s, VI=127

Metal-based detergent (A)
(A1) Metallic salicylate (A1-1) Magnesium salicylate (total base number 340 mgKOH/g, magnesium content 7.5% by mass)
(A1-2) Calcium salicylate 1 (total base number 350 mgKOH/g, calcium content 12.0% by mass)
(A1-3) Calcium salicylate 2 (total base number 220 mgKOH/g, calcium content 8.0 mass%)

(A2) Metal-based sulfonate (A2-1) Magnesium sulfonate (total base number 400 mgKOH/g, magnesium content 9.0% by mass)
(A2-2) Calcium sulfonate (total base number 300 mgKOH/g, calcium content 11.6% by mass)

Molybdenum-based friction modifier (B)
Molybdenum-based friction modifier: MoDTC (a compound in which X ₁ and X ₂ are O and Y ₁ and Y ₂ are S in the above formula [1]. Molybdenum content 10% by mass)

Anti-wear agent Anti- wear agent 1: pri-ZnDTP (primary alkyl group) Anti-wear agent 2: sec-ZnDTP (secondary alkyl group)

Other additives <br />Antioxidant:phenolic antioxidant Anti-ash dispersant:succinimide viscosity index improver:polymethacrylate defoamer:dimethyl silicone

Examples 1-12 and Comparative Examples 1-8
Lubricating oil compositions were prepared by mixing the components in the amounts shown in Tables 1 and 3, respectively. The amounts of the magnesium-based detergent, the calcium-based detergent, and the molybdenum-based friction modifier described in Tables 1 and 3 are the concentrations (in order of mass) of magnesium, calcium, and molybdenum with respect to the total amount of the lubricating oil composition (in order). , [Mg], [Ca], and [B]). The amounts of the antiwear agent and other additives are parts by mass relative to the total amount (100 parts by mass) of the lubricating oil composition. The amounts of the magnesium-based detergent and the calcium-based detergent were such that the total molar amounts of magnesium and calcium contained in these detergents were the same in all Examples and Comparative Examples. The following tests were performed on the obtained composition. The results are shown in Tables 2 and 4.

In Tables 1 and 3 below, [A] is the concentration of total magnesium and total calcium contained in the lubricating oil composition in terms of total mass ppm (ie, Mg and Ca derived from magnesium sulfonate and calcium sulfonate are also included). , [A1] is the concentration (that is, [Ca]+[Mg]) of the total mass ppm of magnesium and calcium derived from the (A1) metal salicylate in the lubricating oil composition. [A1]/[A] is the concentration [A1] based on the total mass ppm of magnesium and calcium derived from the metal-based salicylate relative to the concentration [A] based on the total mass ppm of total magnesium and total calcium contained in the lubricating oil composition. ]% by mass.

(1) High temperature high shear viscosity at 150°C (HTHS150)
It was measured according to ASTM D4683.

(2) CCS viscosity at -35°C (CCS viscosity)
Measured in accordance with ASTM D5293.

(3) Kinematic viscosity at 100°C (KV100)
It was measured at 100° C. according to ASTM D445.

(4) Torque reduction rate Using the lubricating oil compositions obtained in Examples and Comparative Examples as test compositions, torque was measured in a motoring test using a gasoline engine. The engine used was a Toyota 2ZR-FE1.8L in-line 4-cylinder engine, a torque meter was installed between the motor and the engine, and the torque was measured at an oil temperature of 80° C. and an engine speed of 700 RPM. A commercially available GF-50O-20 oil was used as the standard oil, and the torque was measured in the same manner. Torque test composition (T) as compared to the torque of a standard oil _{(T 0),} was calculated reduction rate from the torque of the standard oil _{({(T 0 -T) /} T 0} x100) (%). The larger the reduction rate, the better the fuel consumption. Those with a reduction rate of 5.5% or more were accepted.

(5) The measurement was carried out in accordance with the shell four-ball test (ASTM D4172) except that the number of revolutions of shell wear scar diameter was 1800 rpm, the load was 40 kgf, the test temperature was 90° C., and the test time was 30 minutes. Those having a wear scar diameter of 0.7 mm or less were accepted.

(6) Hot tube test (evaluation of high temperature cleanliness)
The lubricating oil composition was continuously flowed in a glass tube having an inner diameter of 2 mm at 0.3 ml/hour and air at 10 ml/sec for 16 hours while maintaining the temperature of the glass tube at 270°C. The lacquer attached to the glass tube and the color sample were compared, and a score was given as 10 points for transparent and 0 points for black. The higher the score, the better the high temperature cleanability. Those with a score of 5.0 or higher were accepted.

As shown in Table 4, the compositions of Comparative Examples 1 to 3 having a large content of calcium salicylate (A1) had a low torque reduction rate, and the composition of Comparative Example 6 having a large amount of magnesium salicylate (A) was worn. Is big. Further, the compositions of Comparative Examples 4 and 5 in which the amount of the molybdenum-based friction modifier (B) is less than the lower limit of the present invention have a low torque reduction rate and poor high temperature cleanability. Furthermore, the compositions of Comparative Examples 7 and 8 containing no metal-based salicylate have a low torque reduction rate and inferior high temperature cleanability.
On the other hand, as shown in Table 2, the lubricating oil composition of the present invention has low kinematic viscosity at 100°C, but has little wear, and has a high torque reduction rate and high-temperature detergency.

Claims (12)

A lubricating oil composition comprising a lubricating base oil, (A1) a metal-based salicylate, and (B) a molybdenum-based friction modifier,
The amount of component (B) is in the range of 500 to 1500 mass ppm as the concentration [B] based on mass ppm of molybdenum in the lubricating oil composition,
The component (A1) is a combination of magnesium salicylate and calcium salicylate, and the total base number of the magnesium salicylate and calcium salicylate is 100 to 450 mgKOH/g, respectively, and the amount of the calcium salicylate in the lubricating oil composition is calcium salicylate is shea 300-1500 ppm by weight as the concentration [Ca] by mass ppm rates from calcium, the amount of said magnesium salicylate is a concentration [Mg] by mass ppm of magnesium from the magnesium salicylate lubricating oil composition The lubricating oil composition is 100 to 1600 mass ppm, and is in the range of 400 to 3000 mass ppm as the total of [Ca] and [Mg]. A lubricating oil composition comprising a lubricating base oil, (A1) a metal-based salicylate, and (B) a molybdenum-based friction modifier,
The amount of component (B) is in the range of 500 to 1500 mass ppm as the concentration [B] based on mass ppm of molybdenum in the lubricating oil composition,
The component (A1) is at least one magnesium salicylate, and the amount of the magnesium salicylate is 200 to 1800 mass ppm as a concentration [Mg] in terms of mass ppm of magnesium derived from the magnesium salicylate in the lubricating oil composition. A lubricating oil composition comprising: The lubricating oil composition according to claim 2, wherein the total base number of the magnesium salicylate is 100 to 450 mgKOH/g. The lubricating oil composition may further contain a metal-based detergent other than the component (A1) as the (A) metal-based detergent, and the mass of the component (A1) with respect to the total mass of the (A) metal-based detergent is the relative concentration [a] according to the total mass ppm of metal from the metallic detergent in the lubricating oil composition is in the range of 5 to 100 wt% as a percentage of [Ca] and [Mg], claim 1-3 The lubricating oil composition according to any one of 1 . The lubricating oil composition further comprises (A) a metal-based detergent (A2) other than the component (A1) as the metal-based detergent, and the (A2) component contains at least one selected from magnesium, calcium and sodium. ,
The amount of the metallic detergent (A) is represented by the following formula (1):
[A]/[B]≦4.5 (1)
([A] is the concentration of total mass ppm of magnesium, calcium and sodium in the lubricating oil composition)
The lubricating oil composition according to any one of claims 1 to 4, which satisfies the above condition. (A1) The amount of metal salicylate is represented by the following formula (2):
[A1]/[B]<4.5 (2)
([A1] is the concentration of the total mass ppm of magnesium and calcium derived from the component (A1) in the lubricating oil composition (the above [Ca]+the above [Mg]))
The lubricating oil composition according to any one of claims 1 to 5, which satisfies the above condition. The lubricating oil composition according to any one of claims 1 to 6, further comprising zinc dithiophosphate having a secondary alkyl group in the lubricating oil composition in an amount of 0.1 to 5.0% by mass. CCS viscosity at -35 ° C. is not more than 6.2Pa · s, the lubricating oil composition of any one of claims 1-7. High-temperature high-shear viscosity at 0.99 ° C. (HTHS viscosity) is 1.7~2.9mPa · s, the lubricating oil composition of any one of claims 1-8. Kinematic viscosity at 100 ° C. is less than 8.2 mm ² / s, the lubricating oil composition of any one of claims 1-9. The lubricating oil composition according to claim 10, wherein the high temperature high shear viscosity (HTHS viscosity) at 150°C is 1.7 to 2.6 mPa·s. It is for an internal combustion engine, the lubricating oil composition of any one of claims 1 to 11.