WO2023190101A1

WO2023190101A1 - Lubricating oil composition for internal combustion engines

Info

Publication number: WO2023190101A1
Application number: PCT/JP2023/011689
Authority: WO
Inventors: 翔瑚江龍; 穰兼子
Original assignee: Ｅｎｅｏｓ株式会社
Priority date: 2022-03-29
Filing date: 2023-03-24
Publication date: 2023-10-05

Abstract

Provided is a lubricating oil composition for internal combustion engines, comprising: (A) a lubricating oil base oil; (B) a molybdenum-based friction modifier that contains molybdenum in an amount of 50 ppm by mass to 2000 ppm by mass inclusive relative to the whole mass of the composition; (C) R¹-NH-(CH₂)n₁-NH₂ (wherein R¹ represents an aliphatic hydrocarbon group having 4 to 24 carbon atoms and optionally having a substituent, an alicyclic hydrocarbon group having 6 to 15 carbon atoms and optionally having a substituent, or an aromatic hydrocarbon group having 6 to 15 carbon atoms and optionally having a substituent; and n1 represents 2 to 5) that acts as an ash-free friction modifier; and (D) magnesium carbonate salicylate that acts as a metal-based cleaning agent.

Description

Lubricating oil composition for internal combustion engines

The present invention relates to a lubricating oil composition for internal combustion engines.

In recent years, lubricating oil compositions for internal combustion engines for automobiles have been studied for the purpose of fuel efficiency. In particular, the introduction of technologies such as downsizing turbos, which replace conventional naturally aspirated gasoline engines with lower-displacement engines equipped with superchargers (supercharged downsizing engines), with the aim of reducing the fuel consumption of internal combustion engines for automobiles. In response to this, engine oils are required to have LSPI prevention performance, as well as friction reduction performance that leads to further fuel efficiency and improved cleanliness that leads to longer life.
In the supercharged downsized engine mentioned above, when the torque is increased in the low rotation range, a phenomenon occurs in which ignition occurs in the cylinder earlier than the scheduled timing (LSPI: Low Speed Pre-Ignition). There is. When LSPI occurs, energy loss increases, which not only limits improvements in fuel efficiency and low-speed torque, but also leads to engine damage.

Therefore, in order to improve the cleanliness, at least one viscosity index improver selected from a calcium-based detergent, a magnesium-based detergent, a styrene-diene copolymer and an ethylene-α-olefin copolymer, A lubricating oil composition containing a nitrogen-containing dispersant and the like has been proposed (Patent Document 1).
However, there is a problem in that the blending of Ca and Mg in the detergent deteriorates fuel efficiency.

Furthermore, although it is known that fuel efficiency can be improved by increasing the MoDTC concentration, in engines equipped with GPF or DPF, it is preferable not to increase the metal concentration in the engine oil. It is not preferable to increase the friction modifier containing metal.
As a result of extensive studies, the inventors of the present invention have found that by using a friction modifier having a specific prescription system in combination, the fuel efficiency of engine oil can be significantly improved without increasing the MoDTC concentration.

Japanese Patent Application Publication No. 2020-76004

The problem to be solved by the present invention is to provide a lubricating oil composition for internal combustion engines that is excellent in fuel efficiency.

In order to solve the above-mentioned problems, the present inventor conducted intensive studies and found that it is possible to provide a lubricating oil composition for internal combustion engines that maintains LSPI prevention performance and cleanliness performance and is excellent in fuel efficiency. Ta.
The present invention was made based on this knowledge and consists of the following.

<1>
(A) Lubricating base oil;
(B) a molybdenum-based friction modifier containing molybdenum in an amount of 50 mass ppm or more and 2000 mass ppm or less based on the total amount of the composition;
(C) As an ashless friction modifier,
R ¹ -NH-(CH ₂ ) _n1 -NH ₂ (1)
(In formula (1), R ¹ is an aliphatic hydrocarbon group having 4 to 24 carbon atoms which may have a substituent, or an alicyclic carbonized group having 6 to 15 carbon atoms which may have a substituent) represents a hydrogen group or an aromatic hydrocarbon group having 6 to 15 carbon atoms that may have a substituent, and n1 represents 2 to 5.)
(D) A lubricating oil composition for an internal combustion engine, containing magnesium carbonate salicylate as a metal-based detergent.
<2>
The lubricating oil composition for an internal combustion engine according to <1>, wherein the lubricating base oil (A) has a kinematic viscosity at 100° C. of 2.0 mm ² /s or more and 8.0 mm ² /s or less.
<3>
(B) The lubricating oil composition for an internal combustion engine according to <1> or <2>, wherein the molybdenum-based friction modifier has a molybdenum content of 300 mass ppm or more and 1000 mass ppm or less based on the total amount of the composition.
<4>
(B) The lubricating oil composition for an internal combustion engine according to any one of <1> to <3>, wherein the molybdenum-based friction modifier is molybdenum dithiocarbamate (MoDTC).
<5>
(C) The lubricating oil composition for an internal combustion engine according to any one of <1> to <4>, wherein the ashless friction modifier is N-oleylpropanediamine.
<6>
(C) The lubricating oil composition for an internal combustion engine according to <5>, further containing N-oleyl-N'-acylpropanediamine as an ashless friction modifier.
<7>
(C) The lubricating oil composition for an internal combustion engine according to <6>, further containing oleic acid as an ashless friction modifier.
<8>
(C) The lubricating oil for internal combustion engines according to any one of <1> to <7>, wherein the amount of nitrogen derived from the component of formula (1) is 10 mass ppm or more as the ashless friction modifier. Composition.
<9>
(E) The lubricating oil composition for internal combustion engines according to any one of <1> to <8>, further containing polymethacrylate (PMA) as a viscosity index improver.
<10>
(F) For the internal combustion engine according to any one of <1> to <9>, further containing an amine antioxidant as an antioxidant in a range equal to or higher than the mass fraction of the phenolic antioxidant. Lubricating oil composition.
<11>
(G) The lubricating oil composition for an internal combustion engine according to any one of <1> to <10>, further containing zinc dialkyldithiophosphate (ZnDTP) as an anti-wear agent.
<12>
The lubricating oil composition for an internal combustion engine according to any one of <1> to <11>, which has a kinematic viscosity at 100° C. of 4.0 mm ² /s or more and 12.5 mm ² /s or less.
<13>
The lubricating oil composition for an internal combustion engine according to any one of <1> to <12>, which is used in an engine equipped with a gasoline particulate filter (GPF).
<14>
The lubricating oil composition for an internal combustion engine according to any one of <1> to <12>, which is used in a hybrid vehicle equipped with an electric motor.

The lubricating oil composition of the present invention has the extraordinary effect of significantly improving fuel efficiency in internal combustion engines.

Hereinafter, the present invention will be explained in detail based on its preferred embodiments.

The lubricating oil composition for internal combustion engines of the present invention includes a lubricating oil base oil, a molybdenum-based friction modifier containing a molybdenum amount of 50 mass ppm or more and 2000 mass ppm or less, based on the total amount of the composition.
As an ashless friction modifier,
R ¹ -NH-(CH ₂ ) _n1 -NH ₂ (1)
(In formula (1), R ¹ is an aliphatic hydrocarbon group having 4 to 24 carbon atoms which may have a substituent, or an alicyclic carbonized group having 6 to 15 carbon atoms which may have a substituent) represents a hydrogen group or an aromatic hydrocarbon group having 6 to 15 carbon atoms which may have a substituent, and n1 represents 2 to 5);
Contains magnesium carbonate sulfonate as a metal detergent.

[Lubricating base oil (A)]
As the base oil of the present invention, either mineral base oil or synthetic base oil can be used. The kinematic viscosity at 100° C. of the lubricating base oil of the present invention is 2.0 mm ² /s or more and 8.0 mm ² /s or less, preferably 3.0 mm ² /s or more and 6.0 mm ² /s or less, and more. Preferably it is 3.0 mm ² /s or more and 4.5 mm ² /s or less, most preferably 3.0 mm ² /s or more and 4.2 mm ² /s or less. When the kinematic viscosity at 100° C. is 8.0 mm ² /s or less, sufficient fuel efficiency can be obtained. Further, by having a kinematic viscosity of 2.0 mm ² /s or more at 100° C., sufficient fuel efficiency can be obtained. Furthermore, since the kinematic viscosity at 100° C. is 2.0 mm ² /s or more, it is possible to ensure the formation of an oil film at the lubricated locations, resulting in excellent lubricity.
Note that in this specification, the kinematic viscosity at 100°C means the kinematic viscosity at 100°C measured in accordance with ASTM D-445.

The viscosity index of the lubricating base oil of the present invention is preferably 80 or more, more preferably 100 or more. If the viscosity index is within the above numerical range, the viscosity-temperature characteristics, thermal/oxidation stability, and volatilization prevention properties of the lubricating oil composition will be good, and it will be possible to reduce the friction coefficient and improve the friction prevention property. Become.
Note that in this specification, the viscosity index means a viscosity index measured in accordance with ASTM D-2270.

Mineral base oils include base oil fractions obtained by distilling crude oil under normal pressure or further distilling it under reduced pressure and refining distillate oil through various refining processes. The refining process includes hydrorefining, solvent extraction, solvent dewaxing, hydrodewaxing, sulfuric acid washing, clay treatment, etc., and the base oil of the present invention can be obtained by combining these in an appropriate order. . Also useful is a mixture of a plurality of refined oils with different properties obtained from different crude oils or distillate oils by different process combinations and sequences. Either method can be used preferably by adjusting the properties of the base oil obtained so that it satisfies the above-mentioned physical properties.

As the synthetic base oil, it is preferable to use a base material with excellent hydrolytic stability, such as polyolefins such as poly-α-olefins, polybutenes, and copolymers of two or more various olefins, diesters, polyol esters, etc. Examples include ester-based synthetic oils, ether-based synthetic oils such as alkyldiphenyl and polypropylene glycol, polyalkylene glycols, alkylbenzenes, and alkylnaphthalenes. Among these, poly-α-olefin is preferred in terms of oxidation stability and low-temperature fluidity.

As the lubricating base oil, the exemplified synthetic base oils can be used alone or in combination of two or more. Furthermore, it can also be used in combination with the mineral base oil.
When using a mixture of multiple base oils, including synthetic base oils, as long as the base oil mixture satisfies the above physical properties, the individual base oils before mixing must be outside the range of physical properties. can also be used. Therefore, each synthetic base oil does not necessarily have to satisfy the above-mentioned physical properties, but preferably falls within the range of the above-mentioned physical properties.

When the lubricating oil composition is a multigrade oil, the content of the lubricating base oil of the present invention is 80% by mass or more and 95% by mass or less, preferably 85% by mass or more, based on the total amount of the lubricating oil composition. It is 91% by mass or less. When the content of the base oil is within the above numerical range, appropriate lubricity can be ensured, and the additives can be easily maintained in an appropriately dissolved or dispersed state in the lubricating oil composition.

[Molybdenum friction modifier (B)]
The molybdenum friction modifier of the present invention is preferably molybdenum dithiocarbamate (MoDTC). Addition of MoDTC provides the effect of reducing friction in the boundary lubrication region in the lubricating oil composition. The low friction caused by MoDTC is thought to be because MoDTC decomposes due to frictional energy and generates low-friction MoS2 as a tribofilm.
As MoDTC, a compound represented by the following formula (2) can be used.

In the above formula (2), R ³ to R ⁶ may be the same or different, and each is an alkyl group having 2 to 24 carbon atoms or an (alkyl)aryl group having 6 to 24 carbon atoms, preferably 4 to 24 carbon atoms. 13 alkyl group or an (alkyl)aryl group having 10 to 15 carbon atoms. The alkyl group may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched. Note that "(alkyl)aryl group" means "aryl group or alkylaryl group." In the alkylaryl group, the substitution position of the alkyl group on the aromatic ring is arbitrary. Y ¹ to Y ⁴ are each independently a sulfur atom or an oxygen atom, and at least one of Y ¹ to Y ⁴ is a sulfur atom.

Molybdenum-containing compounds other than MoDTC include, for example, molybdenum dithiophosphate; molybdenum compounds (for example, molybdenum oxides such as molybdenum dioxide and molybdenum trioxide; molybdic acids such as orthomolybdic acid, paramolybdic acid, and (poly) molybdic acid sulfide; Molybdate salts such as metal salts and ammonium salts of molybdic acid, molybdenum sulfides such as molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, and molybdenum polysulfide, molybdic acid sulfides, metal salts or amine salts of molybdic sulfide, and chlorides. halogenated molybdenum such as molybdenum) and sulfur-containing organic compounds (e.g., alkyl(thio)xanthates, thiadiazole, mercaptothiadiazole, thiocarbonates, tetrahydrocarbyl thiuram disulfide, bis(di(thio)hydrocarbyl dithiophosphonates) ) disulfides, organic (poly)sulfides, sulfurized esters, etc.) or complexes with other organic compounds; and complexes of sulfur-containing molybdenum compounds such as molybdenum sulfide and molybdic acid sulfide with alkenyl succinimides, etc. Mention may be made of molybdenum-containing compounds containing sulfur. Note that the molybdenum-containing compound may be a mononuclear molybdenum compound or a polynuclear molybdenum compound such as a dinuclear molybdenum compound or a trinuclear molybdenum compound.

Furthermore, as a molybdenum-containing compound other than MoDTC, it is also possible to use a molybdenum-containing compound that does not contain sulfur as a constituent element. Specific examples of molybdenum-containing compounds that do not contain sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, and molybdenum salts of alcohols. Complexes, molybdenum salts of organic acids and molybdenum salts of alcohols are preferred.

The amount of molybdenum in the molybdenum friction modifier based on the total amount of the composition is preferably 30 mass ppm or more and 1000 mass ppm or less, more preferably 300 mass ppm or more and 900 mass ppm or less, and even more preferably 600 mass ppm or more and 900 mass ppm or less. It is not more than 750 ppm by mass and most preferably not more than 750 ppm by mass and not more than 850 ppm by mass. When the amount of molybdenum is 300 mass ppm or more, the friction reduction effect can be improved and the LSPI suppression ability can be further improved. Further, by setting the amount of molybdenum to 1000 mass ppm or less, the storage stability of the lubricating oil composition can be improved. Unless otherwise specified, the content of calcium, magnesium, zinc, phosphorus, boron, and molybdenum elements in oil was measured using inductively coupled plasma optical emission spectroscopy (intensity ratio method) in accordance with JPI-5S-62. It shall be measured by internal standard method)).

[Ashless friction modifier (C)]
The ashless friction modifier of the present invention is represented by the following formula (1).
R ¹ -NH-(CH ₂ ) _n1 -NH ₂ (1)
(In formula (1), R ¹ is an aliphatic hydrocarbon group having 4 to 24 carbon atoms which may have a substituent, or an alicyclic carbonized group having 6 to 15 carbon atoms which may have a substituent) Represents a hydrogen group or an aromatic hydrocarbon group having 6 to 15 carbon atoms that may have a substituent, and n1 represents 2 to 5.)

In the formula, n1 is more preferably 14 to 20, and n2 is more preferably 3.
It is preferable to further contain oleic acid.
More preferably, it contains N-oleylpropanediamine, oleic acid and N-oleyl-N'-acylpropanediamine.

Oleic acid, N-oleylpropanediamine, and N-oleyl-N'-acylpropanediamine contain structures in which the alkyl group is myristyl, palmityl, palmitoleyl, stearyl, linoleyl, or eicosyl in addition to oleyl as a subcomponent. sell.

The amount of nitrogen derived from the relevant component of the ashless friction modifier is preferably 10 ppm or more, more preferably 120 ppm or more. This is because if the amount is less than 10 ppm, fuel saving performance may be impaired, but excessive addition may have an adverse effect on cleanliness maintenance performance and material compatibility. Further, the nitrogen content in the oil shall be measured by chemiluminescence method in accordance with JIS K2609. Further, the nitrogen content in the oil shall be measured by chemiluminescence method in accordance with JIS K2609.

[Metallic detergent (D)]
As the metal-based detergent, magnesium-based salicylates are preferred, and magnesium carbonate salicylates overbased with carbonates (magnesium carbonate) are preferred. Further, they can be used alone or in combination of two or more.

Examples of magnesium salicylate include compounds represented by the following formula (3).

In the above formula (3), R ⁷ each independently represents an alkyl group or alkenyl group having 14 to 30 carbon atoms, and n represents 1 or 2. 1 is preferable as n. Note that when n=2, R ⁷ may be a combination of different groups. Magnesium salicylate may be overbased with carbonate or overbased with borate.

The lower limit of the amount of magnesium derived from magnesium salicylate contained in the lubricating oil composition of the present invention is preferably 50 mass ppm or more, more preferably 100 mass ppm or more, based on the total amount of the lubricating oil composition. The upper limit is preferably 2000 mass ppm or less, more preferably 1000 mass ppm or less. The specific range is preferably 50 mass ppm or more and 2000 mass ppm or less, more preferably 100 mass ppm or more and 1000 mass ppm or less. By controlling the content of magnesium derived from magnesium salicylate within the above range, fuel efficiency can be further improved not only at high oil temperatures but also at low oil temperatures.

(Base number)
The lower limit of the base number of the magnesium salicylate contained in the lubricating oil composition of the present invention is preferably 200 mgKOH/g or more, more preferably 250 mgKOH/g or more, and still more preferably 300 mgKOH/g or more. The upper limit is preferably 600 mgKOH/g or less, more preferably 500 mgKOH/g or less, still more preferably 400 mgKOH/g or less. The specific range is preferably 200 mgKOH/g or more and 600 mgKOH/g or less, more preferably 250 mgKOH/g or more and 500 mgKOH/g or less, and even more preferably 300 mgKOH/g or more and 400 mgKOH/g or less. If it is above the lower limit, the cleanliness will be good. Moreover, when the amount is below the upper limit, the stability of the dissolved state becomes good.
In this specification, the base number means the base number measured by the perchloric acid method in accordance with JIS K2501:2003-9. Further, metal detergents are generally obtained by reaction in a diluent such as a solvent or a lubricating base oil. Therefore, metal-based detergents are commercially distributed in a diluted state with a diluent such as a lubricant base oil. In this specification, the base number of a metal-based detergent means the base number in a state including a diluent.

[Viscosity index improver (E)]
As the viscosity index improver, any viscosity index improver used in the field of lubricating oil compositions can be used without limit as long as the effects of the present invention can be obtained. Viscosity index improvers that can be used include polybutene (PB), polyisobutene (PIB), ethylene-propylene copolymer (EPC), olefin copolymer (OCP), poly(meth)acrylate (PMA), and styrene-diene copolymer (SDC). etc. can be mentioned. Poly(meth)acrylate (PMA) is preferred, and comb-shaped poly(meth)acrylate is more preferred.
These viscosity index improvers can be used alone or in combination of two or more. By using these viscosity index improvers, coking resistance can be improved while maintaining fuel efficiency and high-temperature cleanliness.

The lower limit of the weight average molecular weight (Mw) of the viscosity index improver is preferably 10,000 or more, more preferably 50,000 or more, still more preferably 100,000 or more, and even more preferably 200,000 or more. ,000 or more, and the upper limit is preferably 1,000,000 or less, more preferably 700,000 or less, and even more preferably 500,000 or less.

If the weight average molecular weight of the viscosity index improver is within the above numerical range, a sufficient viscosity index improvement effect can be obtained, excellent fuel efficiency, moderate viscosity increase effect, shear stability and lubricant base oil It has excellent solubility and storage stability.

In this specification, the "weight average molecular weight" and "number average molecular weight" of a polymer mean the weight average molecular weight and number average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC). The GPC measurement conditions are as follows.

The lower limit of the content of the viscosity index improver in terms of resin content is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably is 1.0% by mass or more, and the upper limit is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, still more preferably 3.0% by mass or less. If the content of the viscosity index improver is within the above numerical range, it is possible to further improve coking resistance while maintaining excellent viscosity-temperature characteristics.

[Antioxidant (F)]
As the antioxidant, amine antioxidants and phenolic antioxidants are preferred.
As the amine antioxidant, for example, known amine antioxidants such as alkylated diphenylamine, alkylated phenyl-α-naphthylamine, phenyl-α-naphthylamine, and phenyl-β-naphthylamine can be used. Examples of phenolic antioxidants include known phenolic antioxidants such as 2,6-di-tert-butyl-4-methylphenol (DBPC) and 4,4'-methylenebis(2,6-di-tert-butylphenol). Antioxidants can be used.
An amine antioxidant is contained as an antioxidant in a range that is equal to or higher than the mass fraction of the phenolic antioxidant. As an antioxidant, the content of the amine antioxidant relative to the content of the phenolic antioxidant is preferably 1.0 or more, more preferably 2.0 or more, and even more preferably 2.4 on a mass fraction basis. Above, the most preferred value is 5.0. Within the above numerical range, it is economically rational to reduce the total content of antioxidants while maintaining high-temperature antioxidant performance.

[Anti-wear agent (G)]
As an anti-wear agent, it is preferable to add zinc dialkyldithiophosphate (ZnDTP). For example, examples of zinc dialkyldithiophosphate include compounds represented by the following formula (4).

R ⁸ to R ¹¹ in the above formula (4) are each independently a linear or branched alkyl group having 1 to 24 carbon atoms. This alkyl group may be primary, secondary, or tertiary. As the zinc dialkyldithiophosphate, zinc dithiophosphate having a primary alkyl group (primary ZnDTP) or zinc dithiophosphate having a secondary alkyl group (secondary ZnDTP) is preferable. A material containing zinc dithiophosphate as a main component is preferable because it improves wear resistance.
In the present invention, these zinc dialkyldithiophosphates may be used alone or in combination of two or more.

When the lubricating oil composition of the present invention contains zinc dialkyldithiophosphate, its content is, for example, 0.01% by mass or more and 20% by mass or less, preferably 0.1% by mass or more and 10% by mass, based on the total amount of the composition. The content is more preferably 0.2% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass or more and 2% by mass or less.

The amount of phosphorus derived from zinc dialkyldithiophosphate contained in the lubricating oil composition of the present invention is, for example, 10 mass ppm or more and 2000 mass ppm or less, preferably 550 mass ppm or more and 850 mass ppm or less, based on the total amount of the composition. Preferably it is 700 mass ppm or more and 850 mass ppm or less.

[Dispersant (H)]
As the dispersant, a succinimide-based dispersant is preferred. It is preferred as a compound that effectively disperses and solubilizes insoluble matter derived from lubricating oil compositions or fuels produced in internal combustion engines.
When the lubricating oil composition of the present invention contains a dispersant, its content is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.3% by mass or more and 8% by mass or less, based on the total amount of the composition. It is. When it is at least the lower limit, cleanliness and dispersibility are favorable, and when it is at most the upper limit, the viscosity properties are good, which is preferable from the viewpoint of fuel efficiency performance.

[Other additives]
From the viewpoint of improving fuel efficiency in a lubricating oil composition containing MoDTC, it is preferable to not contain a boric acid-modified dispersant but to contain a non-boric acid-modified dispersant.
In addition to the above, the composition may further contain other components commonly used in lubricating oil compositions, such as a rust preventive, a pour point depressant, a demulsifier, a metal deactivator, and an antifoaming agent.

Examples of rust preventives include petroleum sulfonates, alkylbenzene sulfonates, dinonylnaphthalene sulfonates, alkenyl succinates, and polyhydric alcohol esters. The content of the rust inhibitor is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and preferably 10% by mass or less, based on the total amount of the lubricating oil composition. More preferably, it is 5% by mass or less.

As the pour point depressant, for example, a polymethacrylate polymer that is compatible with the lubricating base oil used can be used. The content of the pour point depressant is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and preferably 10% by mass or less, based on the total amount of the lubricating oil composition. , more preferably 5% by mass or less.

As the demulsifier, known demulsifiers such as polyalkylene glycol nonionic surfactants can be used. When the lubricating oil composition contains a demulsifier, its content may be, for example, 0.005 to 5% by weight, based on the total amount of the composition.

Examples of metal deactivators include imidazoline, pyrimidine derivatives, alkylthiadiazole, mercaptobenzothiazole, benzotriazole or its derivatives, tolyltriazole or its derivatives, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl -2,5-bisdialkyldithiocarbamate, 2-(alkyldithio)benzimidazole, β-(o-carboxybenzylthio)propionitrile and the like. The content of the metal deactivator is based on the total amount of the lubricating oil composition, and the lower limit is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and the upper limit is preferably is 10% by mass or less, more preferably 5% by mass or less.

Examples of antifoaming agents include silicone oil with a kinematic viscosity of 1,000 to 100,000 mm ² /s at 25°C, alkenylsuccinic acid derivatives, esters of polyhydroxy aliphatic alcohols and long-chain fatty acids, and methyl salicylate. , and o-hydroxybenzyl alcohol. The lower limit of the content of the antifoaming agent is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, and the upper limit is preferably 1% by mass or more, based on the total amount of the lubricating oil composition. It is not more than 0.5% by mass, more preferably not more than 0.5% by mass.

[Lubricating oil composition]
The lubricating oil composition of the present invention preferably has a kinematic viscosity at 100°C of 4.0 mm ² /s or more and 12.5 mm 2 /s or less, more preferably 5.0 ^{mm 2} ^/ s or more and 7.9 mm ² /s. It is as follows. If the kinematic viscosity at 100°C is below the above upper limit, sufficient fuel efficiency can be obtained, and when it is above the above lower limit, an oil film will be formed at the lubricated location, resulting in excellent lubricity.
Note that in this specification, the kinematic viscosity at 100°C means the kinematic viscosity at 100°C measured in accordance with ASTM D-445.

The lubricating oil composition of the present invention preferably has a kinematic viscosity at 40°C of 15 mm ² /s or more and 70 mm 2 /s or less, more preferably 20 ^{mm 2} ^/ s or more and 30 mm ² /s or less. If the kinematic viscosity at 40°C is below the above upper limit, sufficient fuel efficiency can be obtained, and if it is above the above lower limit, an oil film will be formed at the lubricated location, resulting in excellent lubricity and low evaporation loss. can do.
Note that in this specification, the kinematic viscosity at 40°C means the kinematic viscosity at 40°C measured in accordance with ASTM D-445.

The viscosity index of the lubricating oil composition is preferably 120 or more and 400 or less, more preferably 130 or more and 300 or less. If the viscosity index of the lubricating oil composition is within the above numerical range, fuel efficiency can be improved while maintaining the HTHS viscosity at 150°C.

The lower limit of the HTHS viscosity at 150° C. of the lubricating oil composition is preferably 1.7 mPa s or more, more preferably 1.8 mPa s or more, and still more preferably 1.9 mPa s or more, Still more preferably 2.0 mPa・s or more, and the upper limit is preferably 3.5 mPa・s or less, more preferably 3.2 mPa・s or less, still more preferably 2.9 mPa・s or less and even more preferably 2.6 mPa·s or less. When the HTHS viscosity at 150° C. of the lubricating oil composition is 3.5 mPa·s or less, even better fuel efficiency can be obtained. If it is less than 1.7 mPa·s, lubricity may be insufficient. In this specification, "HTHS viscosity at 150°C" means high-temperature high-shear viscosity at 150°C measured in accordance with ASTM D-4683.

<HTT test>
Cleanliness was measured in accordance with JPI-5S-55-99. The test conditions were a sample amount of 10 mg, a test temperature of 280° C., and a test time of 16 hours. Lubricating oils with a rating of 2.5 or higher were rated as having good cleanliness.

<TE77>
The friction coefficient was measured using a high-speed reciprocating friction tester (TE77 manufactured by Phoenix Tribology). As test pieces, a flat plate test piece SKS3 with a shape of 58 mm in length x 38 mm in width x 4 mm in thickness and a cylinder test piece EN1A with a shape of 6 mm in diameter x 16 mm in length were used. The load was 10 N or 100 N, the sliding amplitude was 15 mm, the sliding frequency was 5 Hz, the test time was 10 minutes, and the test temperature was 70°C or 100°C. For each friction coefficient, the average value of the test time of 5 to 10 minutes was adopted.

The lower limit of the nitrogen content in the lubricating oil composition is 700 mass ppm or more, preferably 800 mass ppm or more, and more preferably 900 mass ppm or more, based on the total amount of the lubricating oil composition. More preferably, it is 1000 mass ppm or more, and the upper limit is preferably 3000 mass ppm or less, more preferably 2500 mass ppm or less, and even more preferably 2000 mass ppm or less. If the nitrogen content in the lubricating oil composition is within the above numerical range, fuel efficiency can be improved while maintaining coking resistance.

[Applications of lubricating oil composition]
Since the lubricating oil composition of the present invention has LSPI prevention properties, friction reduction properties, cleanliness, and fuel efficiency, it is suitable for lubricating engines equipped with GPF, hybrid vehicles equipped with electric motors, engines equipped with superchargers, etc. can also be used.

The present invention will be described below using an example that is an embodiment of the present invention, but the present invention is not limited to the following embodiments. Unless otherwise specified, % indicates mass %.

<Formulation of lubricating oil composition>
For each Example and each Comparative Example, a lubricating oil composition was obtained by blending the lubricating base oil and additives at the blending ratios shown in Table 1. The blending amount of the additive is based on the total amount of the lubricating oil composition.
The following evaluation tests were conducted on the obtained lubricating oil composition. The results are shown in Table 1.

(A) Lubricant base oil Base oil A: Group III base oil 100°C kinematic viscosity 4.2 mm ² /s, 40°C kinematic viscosity 19.4 mm ² /s
Base oil B: Group II base oil 100°C kinematic viscosity 3.0 mm ² /s, 40°C kinematic viscosity 12.6 mm ² /s
Base oil C: Group IV base oil, 100°C kinematic viscosity 4.1 mm ² /s, 40°C kinematic viscosity 19.0 mm ² /s
Base oil D: Group V base oil, 100°C kinematic viscosity 3.1 mm ² /s, 40°C kinematic viscosity 10.9 mm ² /s

(B) Molybdenum friction modifier MoDTC: Mo 10% by mass, N 1.5% by mass

(C) Ashless friction modifier Ashless friction modifier A: N-oleylpropanediamine, N 9.1% by mass
Ashless friction modifier B: Oleic acid Ashless friction modifier C: N-oleyl-N'-acylpropanediamine, N 4.8% by mass
Ashless friction modifier D: oleylamide, N 5.0% by mass
Ashless friction modifier E: oleylamine, N 5.5% by mass

(D) Metallic detergent Ca carbonate salicylate: Ca 8.0% by mass, base number 230
Boric acid Ca salicylate: Ca 6.8% by mass, base number 190
Mg carbonate salicylate: Mg 7.5% by mass, base number 350

(E) Viscosity index improver Comb-shaped PMA: Mw=490000, Mw/Mn=4.0

(F) Antioxidant Amine-based ashless antioxidant: bis(nonan-1-ylphenyl)amine, N: 3.6% by mass
Phenolic ashless antioxidant: benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, C7-C9 side chain alkyl ester

(G) Anti-wear agent sec-ZnDTP: P 8.5% by mass, Zn 10.4% by mass, S 17.8% by mass
pri-ZnDTP: P 7.0% by mass, Zn 8.6% by mass, S 14.8% by mass

(H) Dispersant Succinimide dispersant A: B 0.50% by mass, N 1.50% by mass
Succinimide dispersant B: B 0% by mass, N 1.50% by mass

〔Evaluation results〕
Compared to Comparative Example 1, Example 1 was able to reduce the friction coefficient by containing the ashless friction modifier. FM is an abbreviation for Friction Modifier.
Comparative Example 2 and Comparative Example 3 are common in that they contain nitrogen, but are examples in which a nitrogen-containing FM having a structure different from that of Example 1 was used. Therefore, it was found that the friction coefficient reduction effect was inferior to that of the FM of Example 1, and the cleanliness was also inferior.
Comparative Example 4 is an example in which the Ca concentration was not increased from the viewpoint of LSPI prevention, and Mg was not contained. Although a certain friction reduction effect could be confirmed, the cleanliness was poor, and as a result, Example 1 shows the usefulness of containing Mg.
Example 2 is an example in which the amount of friction modifier was changed from Example 1. The optimum concentration value differs depending on the conditions for measuring the friction coefficient, and can be suitably adjusted depending on the operating conditions of the actual machine to which the lubricating oil composition is applied.
Example 3 is an example in which the type of anion of the Ca detergent, which is a detergent contained in addition to the Mg detergent in the present invention, is changed.
Examples 4 and 5 are examples in which the antioxidant was adjusted. If the overall mass fraction is not changed, no significant deterioration occurs when it is increased, and it can be suitably adjusted.
Examples 6 and 7 are examples in which the viscosity grade specified by SAE J300 was changed, and Examples 8, 9, and 10 are examples in which the base oil was changed from Group III alone. It can be suitably adjusted according to the required values of cleanliness and friction reduction performance.
Example 11 is an example in which the type of dispersant was changed. It can be seen that from the viewpoint of friction reduction performance, it is preferable to use a non-boric acid modified dispersant.
Example 12 is an example in which the Ca concentration and Mg concentration were changed. It can be suitably adjusted according to the required values of cleanliness and friction reduction performance. This is also an example in which the amount of Mo compound is increased, which is an effective method for improving friction reduction performance.
Compared to Comparative Example 5, Example 1 was able to reduce the friction coefficient by containing a molybdenum-based friction modifier.
Examples 1, 14, and 15 are examples in which the amount of the molybdenum friction modifier was changed. It was found that if these amounts were added, no significant change in physical properties was observed.

Since the lubricating oil composition of the present invention has excellent fuel efficiency as a friction modifier, it can also be used to lubricate engines equipped with GPF, hybrid vehicle engines equipped with electric motors, engines equipped with superchargers, etc. .

Claims

(A) Lubricating base oil;
(B) a molybdenum-based friction modifier containing molybdenum in an amount of 50 mass ppm or more and 2000 mass ppm or less based on the total amount of the composition;
(C) As an ashless friction modifier,
R 1 -NH-(CH 2 ) n1 -NH 2 (1)
(In formula (1), R 1 is an aliphatic hydrocarbon group having 4 to 24 carbon atoms which may have a substituent, or an alicyclic carbonized group having 6 to 15 carbon atoms which may have a substituent) represents a hydrogen group or an aromatic hydrocarbon group having 6 to 15 carbon atoms which may have a substituent, and n1 represents 2 to 5);
(D) A lubricating oil composition for an internal combustion engine, containing magnesium carbonate salicylate as a metal-based detergent.
The lubricating oil composition for an internal combustion engine according to claim 1, wherein the lubricating oil base oil (A) has a kinematic viscosity at 100°C of 2.0 mm 2 /s or more and 8.0 mm 2 /s or less.
The lubricating oil composition for an internal combustion engine according to claim 1 or 2, wherein the molybdenum friction modifier (B) has a molybdenum amount of 300 to 1000 ppm by mass based on the total amount of the composition.
The lubricating oil composition for an internal combustion engine according to claim 3, wherein the molybdenum friction modifier (B) is molybdenum dithiocarbamate (MoDTC).
The lubricating oil composition for an internal combustion engine according to claim 1 or 2, wherein the ashless friction modifier (C) is N-oleylpropanediamine.
The lubricating oil composition for an internal combustion engine according to claim 5, further comprising N-oleyl-N'-acylpropanediamine as (C) an ashless friction modifier.
The lubricating oil composition for an internal combustion engine according to claim 6, further comprising oleic acid as (C) an ashless friction modifier.
The lubricating oil composition for an internal combustion engine according to claim 1 or 2, wherein the amount of nitrogen derived from the component of formula (1) as the ashless friction modifier (C) is 10 ppm or more.
The lubricating oil composition for an internal combustion engine according to claim 1 or 2, further comprising polymethacrylate (PMA) as (E) a viscosity index improver.
The lubricating oil composition for an internal combustion engine according to claim 1 or 2, further comprising an amine antioxidant as the antioxidant (F) in a range that is equal to or higher than the mass fraction of the phenolic antioxidant.
(G) The lubricating oil composition for an internal combustion engine according to claim 1, further comprising zinc dialkyldithiophosphate (ZnDTP) as an anti-wear agent.
The lubricating oil composition for an internal combustion engine according to claim 1 or 2, having a kinematic viscosity at 100°C of 4.0 mm 2 /s or more and 12.5 mm 2 /s or less.
The lubricating oil composition for an internal combustion engine according to claim 1 or 2, which is used for an engine equipped with a gasoline particulate filter (GPF).
The lubricating oil composition for an internal combustion engine according to claim 1 or 2, which is used for a hybrid vehicle equipped with an electric motor.