JP2023045023A - Lubricant composition for internal combustion engine - Google Patents

Abstract

To provide a lubricant composition for an internal combustion engine having improved corrosion resistance while maintaining fuel economy at low and high temperatures.SOLUTION: A lubricant composition for an internal combustion engine that can solve above problems comprises at least one ashless friction modifier selected from (A) a lubricant base oil, (B) an organic molybdenum compound, (C) an alicyclic epoxy compound, (D) a triazole or triazole derivative, and (E) an amino acid compound, an amine compound, an urea compound, a fatty acid ester compound, that have an alkyl group, an alkenyl group, or an acyl group having 12 to 30 carbon atoms, and derivatives thereof, wherein an amount of molybdenum derived from the compound (B) is 400 mass ppm or more based on a total amount of the composition, and the amount of nitrogen derived from the compound (E) is 400 mass ppm or less based on the total amount of the composition.SELECTED DRAWING: None

Description

The present invention relates to a lubricating oil composition for internal combustion engines. More particularly, it relates to a lubricating oil composition for internal combustion engines that has improved corrosion resistance while maintaining fuel efficiency at low and high temperatures.

Since its invention, the internal combustion engine has served as a power source for various means of transportation for many years. In recent years, fuel efficiency required for internal combustion engines is increasing. In order to meet this demand, lubricating oils for internal combustion engines are also required to have high fuel-saving performance.

Organo-molybdenum compounds or ashless friction modifiers are used as friction modifiers for the purpose of improving the fuel efficiency of lubricating oils for internal combustion engines (Patent Document 1). However, the use of organo-molybdenum compounds or ashless friction modifiers can exacerbate the corrosiveness of internal combustion engine lubricating oils. In addition, it has been very difficult to obtain the desired effect of improving fuel economy under both low and high temperature conditions.

Japanese Patent Application Laid-Open No. 2010-095662

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil composition for internal combustion engines that has improved corrosion resistance while maintaining fuel efficiency at low and high temperatures.

The present inventors have made intensive studies to obtain a lubricating oil composition for internal combustion engines that has improved corrosion resistance while maintaining fuel efficiency at low and high temperatures. Therefore, by using an organic molybdenum compound and a specific ashless friction modifier together, and further by adding an alicyclic epoxy compound and triazole or a triazole derivative, corrosion resistance can be maintained while maintaining fuel efficiency at low and high temperatures. It was confirmed that a lubricating oil composition for an internal combustion engine with improved was obtained, and the present invention was completed.

The present invention has been made based on such findings, and is as follows.
<1>
(A) lubricating base oil,
(B) an organomolybdenum compound,
(C) an alicyclic epoxy compound,
(D) a triazole or triazole derivative, and (E) an amino acid compound, an amine compound, a urea compound, a fatty acid ester compound, and derivatives thereof having an alkyl group, alkenyl group, or acyl group having 12 to 30 carbon atoms. A lubricating oil composition for an internal combustion engine comprising at least one ashless friction modifier comprising
The amount of molybdenum derived from the component (B) is 400 mass ppm or more based on the total amount of the composition,
A lubricating oil composition for an internal combustion engine, wherein the amount of nitrogen derived from the component (E) is 400 mass ppm or less based on the total amount of the composition.
<2>
(F) The lubricating oil composition for an internal combustion engine according to <1>, further comprising a poly(meth)acrylate as a viscosity index improver and having a viscosity index of 200 or more and 350 or less.
<3>
The lubricating oil composition for internal combustion engines according to <1> or <2>, wherein the amount of molybdenum derived from the component (B) is 2,000 mass ppm or less based on the total amount of the composition.
<4>
The lubricating oil composition for internal combustion engines according to any one of <1> to <3>, which has a sulfated ash content of 0.8% by mass or less.
<5>
(A) The lubricating oil for internal combustion engines according to any one of <1> to <4>, wherein the kinematic viscosity at 100° C. of the lubricating base oil is 3.0 mm ² /s or more and 6.0 mm ² /s or less. Composition.
<6>
(E) The lubricating oil composition for internal combustion engines according to any one of <1> to <5>, wherein the ashless friction modifier is a nitrogen-containing ashless friction modifier.
<7>
(A) the amount of lubricating base oil is 50% by mass or more and 95% by mass or less based on the total amount of the composition;
(C) The amount of the alicyclic epoxy compound is 0.01% by mass or more and 2% by mass or less, based on the total amount of the composition, and (D) The amount of the triazole or triazole derivative is 0, based on the total amount of the composition. The lubricating oil composition for an internal combustion engine according to any one of <1> to <6>, which is .001% by mass or more and 1% by mass or less.

According to the lubricating oil composition for internal combustion engines of the present invention, it is possible to provide a lubricating oil composition for internal combustion engines that has improved corrosion resistance while maintaining fuel efficiency at low and high temperatures.

[A] Lubricating Base Oil As the lubricating base oil used in the lubricating oil composition of the present invention, either a mineral base oil or a synthetic base oil can be used. In the lubricating oil composition of the present invention, it is preferred to use a mineral base oil as the lubricating base oil.

As the mineral base oil, a distillate obtained by atmospheric distillation of crude oil can be used. Lubricating oil fractions obtained by refining the distillate obtained by further vacuum distillation of this distillate by various refining processes can also be used. As the refining process, hydrorefining, solvent extraction, solvent dewaxing, hydrodewaxing, sulfuric acid washing, clay treatment, etc. can be combined as appropriate. A lubricating base oil that can be used in the lubricating oil composition of the present invention can be obtained by combining these refining processes in an appropriate order. Mixtures of refined oils with different properties obtained by subjecting different crude oils or distillates to different combinations of refining processes can also be used.

As the mineral base oil used in the lubricating oil composition of the present invention, it is preferable to use one belonging to Group III base oil in the API classification. API Group III base oils are mineral base oils having a sulfur content of 0.03 wt.% or less, a saturates content of 90 wt.% or more, and a viscosity index of 120 or more. Multiple types of Group III base oils may be used, or only one type may be used.
As the mineral base oil used in the lubricating oil composition of the present invention, those belonging to Group II base oil in the API classification can also be used. API Group II base oils are mineral base oils having a sulfur content of 0.03 mass % or less, a saturate content of 90 mass % or more, and a viscosity index of 80 or more and less than 120. Multiple types of Group II base oils may be used, or only one type may be used. Mixtures of Group II base oils and Group III base oils are preferably used.

The lubricating oil composition of the present invention may contain only a mineral base oil as the lubricating base oil, or may contain other lubricating base oils. Specifically, in the present invention, the content of the mineral base oil is based on the lubricating base oil, for example, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass 95% by mass or more, or 99% by mass or more.

In the lubricating oil composition of the present invention, a synthetic base oil may be used as the lubricating base oil. Synthetic base oils include poly-α-olefins and their hydrides, isobutene oligomers and their hydrides, isoparaffins, alkylbenzenes, alkylnaphthalenes, diesters, polyol esters, polyoxyalkylene glycols, dialkyldiphenyl ethers, polyphenyl ethers, and their A mixture etc. are mentioned. Among them, poly-α-olefin is preferred. Polyα-olefins typically include oligomers or co-oligomers of α-olefins having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms (1-octene oligomer, decene oligomer, ethylene-propylene co-oligomer, etc.). and their hydrogenation products.

The kinematic viscosity at 100° C. of the lubricating base oil contained in the lubricating oil composition of the present invention is preferably 3.0 mm ² /s or more, more preferably 3.3 mm ² /s or more, and still more preferably 3.5 mm ² /s or more. Also, the upper limit is preferably 6.0 mm ² /s or less, more preferably 5.5 mm ² /s or less, and even more preferably 4.5 mm ² /s or less. A specific range is preferably 3.0 mm ² /s or more and 6.0 mm ² /s or less, more preferably 3.3 mm ² /s or more and 5.5 mm ² /s or less, still more preferably 3.5 mm ^{2 /} s. s or more and 4.5 mm ² /s or less. When the kinematic viscosity at 100° C. of the lubricating base oil is 6.0 mm ² /s or less, sufficient fuel saving performance can be obtained. In addition, when the kinematic viscosity at 100° C. of the lubricating base oil is 3.0 mm ² /s or more, it is possible to ensure the formation of an oil film at the lubricating points and to reduce the evaporation loss of the lubricating oil composition.

The above kinematic viscosity at 100° C. means the kinematic viscosity in a state in which all the lubricating base oils are mixed, that is, the kinematic viscosity of the base oil as a whole. That is, it does not mean the kinematic viscosity of a specific lubricating base oil when a plurality of base oils are included.
As used herein, "kinematic viscosity at 100°C" means kinematic viscosity at 100°C measured according to ASTM D-445.

In the lubricating oil composition of the present invention, the content of the lubricating base oil is based on the total amount of the composition, for example, 50% by mass or more and 95% by mass or less, preferably 60% by mass or more and 95% by mass or less, more preferably 60% by mass or more. % to 90% by mass, more preferably 60% to 85% by mass, and most preferably 70% to 85% by mass.

[B] Organomolybdenum Compound The lubricating oil composition of the present invention contains an organomolybdenum compound. As the organic molybdenum compound, molybdenum dithiocarbamate (hereinafter sometimes simply referred to as MoDTC) is preferred. Inclusion of the organomolybdenum compound in the lubricating oil composition of the present invention can improve corrosion resistance and reduce the coefficient of friction at low and high temperatures. An organic molybdenum compound may be used individually by 1 type, and may be used in combination of 2 or more types in arbitrary ratios.

As MoDTC, for example, a compound represented by the following formula (1) can be used.

In formula (1), R ¹ to R ⁴ may be the same or different, and are alkyl groups having 2 to 24 carbon atoms or (alkyl)aryl groups having 6 to 24 carbon atoms, preferably 4 to 4 carbon atoms. 13 alkyl groups or (alkyl)aryl groups having 10 to 15 carbon atoms. Alkyl groups can be primary, secondary or tertiary alkyl groups, and can be straight chain or branched. In addition, "(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. X ¹ to X ⁴ are each independently a sulfur atom or an oxygen atom, and at least one of X ¹ to X ⁴ is a sulfur atom.

Examples of organic molybdenum compounds other than MoDTC include molybdenum dithiophosphate, molybdenum oxide, molybdic acid, molybdates such as ammonium salts, molybdenum disulfide, molybdenum sulfide, molybdic acid sulfide, sulfur-containing organic molybdenum compounds, and the like. be able to.

The amount of molybdenum derived from the organic molybdenum compound is 400 ppm by mass or more based on the total amount of the composition. The amount of molybdenum derived from the organomolybdenum compound is preferably 500 mass ppm or more, more preferably 600 mass ppm or more, and even more preferably 700 mass ppm or more. The upper limit is preferably 2000 mass ppm or less, more preferably 1500 mass ppm or less, even more preferably 1200 mass ppm or less, most preferably 1000 mass ppm or less. A specific range is preferably 400 mass ppm or more and 2000 mass ppm or less, more preferably 500 mass ppm or more and 1500 mass ppm or less, still more preferably 600 mass ppm or more and 1200 mass ppm or less, most preferably 700 mass ppm or more and 1000 mass ppm or more. Mass ppm or less. When the molybdenum content is 400 ppm by mass or more, fuel economy performance can be improved. In addition, when the molybdenum content is 2000 ppm by mass or less, the detergency of the lubricating oil composition can be enhanced. The amount of molybdenum in the oil shall be measured by inductively coupled plasma atomic emission spectrometry (intensity ratio method (internal standard method)) in accordance with JPI-5S-62.

[C] Alicyclic Epoxy Compound The lubricating oil composition of the present invention contains an alicyclic epoxy compound. The alicyclic epoxy compound is not particularly limited as long as it is a compound having an alicyclic epoxy group in its molecule. Corrosion resistance can be improved by including an epoxy compound in the lubricating oil composition of the present invention. The alicyclic epoxy compounds may be used singly or in combination of two or more at any ratio.

The alicyclic epoxy group includes, for example, a compound in which an oxygen atom is bonded to two adjacent carbon atoms constituting a cycloaliphatic skeleton, or a compound in which an oxygen atom is bonded to two non-adjacent carbon atoms. and a compound formed by The alicyclic epoxy group is preferably a compound formed by bonding oxygen atoms to two adjacent carbon atoms constituting a cycloaliphatic skeleton. The cycloaliphatic backbone is preferably a 5- to 8-membered ring, more preferably a 5- or 6-membered ring, even more preferably a 6-membered ring.
The alicyclic epoxy group can be a group represented by formula (2) below, ie, a 3,4-epoxycyclohexyl group.

Although the number of alicyclic epoxy groups in the alicyclic epoxy compound is not particularly limited, it is preferably 1 to 6, more preferably 2 to 6, still more preferably 2 to 4.

When the number of alicyclic epoxy groups in the alicyclic epoxy compound is two or more, the alicyclic epoxy groups may be bonded to each other with a single bond, or may be bonded via a linking group. . The type of linking group that links the alicyclic epoxy groups together is not particularly limited, but examples of the linking group include a divalent hydrocarbon group, a carbonyl group (-CO-), an ether bond (-O-), Examples thereof include an ester bond (--COO--), a carbonate bond (--OCOO--), and a combination thereof. The divalent hydrocarbon group includes, for example, a linear or branched alkylene group having 1 to 6 carbon atoms, or a divalent alicyclic hydrocarbon group.

Among these, the epoxy compound having an alicyclic epoxy group is a compound represented by the following formula (3), that is, 3',4'-epoxycyclohexylmethyl (3,4-epoxy)cyclohexane carboxylate. is preferred.

Commercially available products such as "Celoxide 2021P" (Daicel Co., Ltd.) can be used as the compound represented by the formula (3).

The content of the alicyclic epoxy compound is preferably 0.01% by mass or more and 2% by mass or less, more preferably 0.1% by mass or more and 1% by mass or less, based on the total amount of the composition. When the content of the epoxy compound is within the above range, the corrosion resistance of the lubricating oil composition of the present invention can be further improved.

[D] Triazole or Triazole Derivative The lubricating oil composition of the present invention contains triazole or a triazole derivative (hereinafter sometimes simply referred to as triazole or the like). By adding triazole or the like to the lubricating oil composition of the present invention, the corrosion resistance of the lubricating oil composition can be improved. Triazole etc. may be used individually by 1 type, and may be used in combination of 2 or more types in arbitrary ratios.

Triazoles and the like can be benzotriazole derivatives. Benzotriazole derivatives include, for example, compounds represented by general formula (4), compounds represented by general formula (5), and the like.

In formulas (4) and (5), R ¹⁰ and R ¹² each represent a hydrogen atom or a methyl group, and R ¹¹ and R ¹³ each represent a hydrogen atom, a hydroxyl group, or a carbon atom containing a nitrogen or oxygen atom. Represents the groups of numbers 1-20. Each of R ¹¹ and R ¹³ is preferably a group having 10 to 20 carbon atoms containing a nitrogen atom.

Triazole and the like may be used as they are commercially available products, or may be prepared by known methods.

The content of triazole or the like is preferably 0.001% by mass or more and 1% by mass or less, more preferably 0.01% by mass or more and 0.1% by mass or less, based on the total amount of the composition. When the content of triazole or the like is within the above range, the corrosion resistance can be further improved.

[E] Ashless Friction Modifier The lubricating oil composition of the present invention comprises an amine compound, a urea compound, an amino acid, a fatty acid ester, and derivatives thereof having an alkyl group, an alkenyl group, or an acyl group having 12 to 30 carbon atoms. at least one ashless friction modifier selected from By including component (E), an ashless friction modifier, in the lubricating oil composition of the present invention, corrosion resistance can be improved and the coefficient of friction at low and high temperatures can be reduced. In the lubricating oil composition of the present invention, the component (E) ashless friction modifier may be used alone, or two or more of them may be used in combination in an arbitrary ratio. It may also contain other types of ashless friction modifiers.

(Amine compound having an alkyl group, alkenyl group, or acyl group having 12 to 30 carbon atoms)
Examples of amine compounds include linear or branched aliphatic monoamine compounds or aliphatic polyamine compounds, and alkylene oxide adducts thereof. The amine compound is preferably an amine compound represented by the following formula (6).

（Ｒ^２０は、炭素数１２～３０のアルキル基、アルケニル基、またはアシル基であり、Ｒ^２１、Ｒ^２２は、それぞれ独立して、水素、アルキル基、アルケニル基、アシル基またはヒドロキシアルキル基である）
式（６）で表されるアミン化合物としては、例えばオレイルアミン、ステアリルアミン等が挙げられる。オレイルアミンが好ましい。
式（６）で表されるアミン化合物としてはまた、２，２’－（オクタデカン－１－イルイミノ）ジエタノールが好ましい。

(R ²⁰ is an alkyl group, alkenyl group, or acyl group having 12 to 30 carbon atoms, and R ²¹ and R ²² are each independently hydrogen, an alkyl group, an alkenyl group, an acyl group, or a hydroxyalkyl group. be)
Examples of the amine compound represented by Formula (6) include oleylamine and stearylamine. Oleylamine is preferred.
2,2'-(Octadecane-1-ylimino)diethanol is also preferred as the amine compound represented by formula (6).

(Urea compound having an alkyl group, alkenyl group, or acyl group having 12 to 30 carbon atoms)
As the urea compound, a compound having a structure represented by the following formula (7) is preferable.

（Ｒ^３０は、炭素数１２～３０のアルキル基、アルケニル基、またはアシル基である）
ウレア化合物は、好ましくは、脂肪族ウレア化合物であり、より好ましくはオクタデセニル尿素である。

(R ³⁰ is an alkyl group, alkenyl group, or acyl group having 12 to 30 carbon atoms)
The urea compound is preferably an aliphatic urea compound, more preferably octadecenyl urea.

(Amino acid compound having an alkyl group, alkenyl group, or acyl group having 12 to 30 carbon atoms)
Examples of amino acid compounds include compounds represented by the following general formula (8).

Here, R ⁴⁰ is an alkyl group, alkenyl group or acyl group having 12 to 30 carbon atoms, R ⁴¹ is an alkyl group having 1 to 4 carbon atoms or hydrogen, and R ⁴² is hydrogen or 1 to 10 carbon atoms. is an alkyl group of The alkyl group may contain a linear or branched or cyclic structure, and the carbon atoms may be substituted with heteroatoms or modified with functional groups such as hydroxyl, carboxyl, or amino groups. good. R ⁴³ is an alkyl group having 1 to 4 carbon atoms or hydrogen, n is 0 or 1, Y is a functional group having an active hydrogen, a hydrocarbon having the functional group, a metal salt of the functional group or ethanolamine salt, or a methoxy group. A hydroxyl group, an amino group, or the like is suitable as the functional group having an active hydrogen for Y in the general formula (8).

As the component (E), the ashless friction modifier, ^R40 is an acyl group having 18 carbon atoms (oleoyl group), ^R41 is a methyl group, and ^R42 is a (Z)-N-methyl-N-(1-oxo-9-octadecynyl)glycine (also known as N-oleoylsarcosine) in which hydrogen, Y is a hydroxyl group, and n is 0 is preferred.

(Fatty acid ester compound having an alkyl group, alkenyl group, or acyl group having 12 to 30 carbon atoms)
A fatty acid ester compound means a compound formed by an ester bond between a carboxyl group of a fatty acid and an alcohol. Examples of fatty acid ester compounds include esters of linear or branched fatty acids and aliphatic monohydric alcohols or aliphatic polyhydric alcohols. Fatty acids may be saturated fatty acids or unsaturated fatty acids. These fatty acid ester compounds may have, for example, 7 to 31 carbon atoms. The fatty acid ester compound is preferably an ester of a fatty acid and an aliphatic polyhydric alcohol, more preferably an ester of a linear fatty acid and an aliphatic polyhydric alcohol, still more preferably a linear unsaturated It is an ester of a fatty acid and an aliphatic polyhydric alcohol. Esters of these aliphatic polyhydric alcohols may be complete esters or partial esters, preferably partial esters. Glycerin monooleate is preferred as the ester of these aliphatic polyhydric alcohols.

The alkyl group, alkenyl group or acyl group having 12 to 30 carbon atoms preferably has 14 to 24 carbon atoms, more preferably 16 to 20 carbon atoms, and still more preferably 18 carbon atoms. The alkyl group, alkenyl group or acyl group having 12 to 30 carbon atoms is most preferably octadecyl group, 9-octadecenyl group or oleoyl group. An alkyl group, alkenyl group, or acyl group may be straight-chain or branched, but preferably straight-chain.

The amount of nitrogen derived from the component (E) ashless friction modifier is 400 mass ppm or less based on the total amount of the composition. The upper limit may be 350 mass ppm or less, or 300 mass ppm or less. The lower limit for the amount of nitrogen from the ashless friction modifier can be 0 ppm by weight or more, 50 ppm by weight or more, or 100 ppm by weight or more. A specific range can be 0 mass ppm or more and 400 mass ppm or less, 50 mass ppm or more and 350 mass ppm or less, or 100 mass ppm or more and 300 mass ppm or less. Corrosion resistance can be improved by setting the amount of nitrogen to 400 ppm by mass or less. The nitrogen element content in the oil shall be measured by a chemiluminescence method in accordance with JIS K2609.

The content of the ashless friction modifier is preferably 0.001% by mass or more and 1.1% by mass or less, more preferably 0.01% by mass or more and 1.0% by mass or less, based on the total amount of the composition. , more preferably 0.1% by mass or more and 0.8% by mass or less.

[F] Viscosity Index Improver The lubricating oil composition of the present invention preferably contains a viscosity index improver. A viscosity index improver means a compound that, when added to a lubricating oil, has the function of reducing changes in the viscosity of the lubricating oil due to changes in temperature.
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. Examples include polybutene (PB) and polyisobutene (PIB). , ethylene-propylene copolymer (EPC), olefin copolymer (OCP), poly(meth)acrylate (PMA), styrene-diene copolymer (SDC), and the like. A preferred viscosity index improver is poly(meth)acrylate (PMA). As the poly(meth)acrylate (PMA), any of dispersed poly(meth)acrylate, non-dispersed poly(meth)acrylate, and comb-type poly(meth)acrylate may be used. More preferably, meth)acrylate and comb-shaped poly(meth)acrylate are used in combination. The combined use of dispersed poly(meth)acrylate and comb-shaped poly(meth)acrylate can further improve fuel economy at high temperatures.

As used herein, "dispersed poly(meth)acrylate" means a poly(meth)acrylate compound having a functional group containing a nitrogen atom, and "non-dispersed poly(meth)acrylate" includes a nitrogen atom. It means a poly(meth)acrylate compound without functional groups. Dispersion type or non-dispersion type poly (meth) acrylate, for example, the ratio of (meth) acrylate structural units represented by the following general formula (9) to all monomer units in the polymer is 10 to 90 mol% can be exemplified by poly(meth)acrylate.

（式（９）中、Ｒ^５０は水素またはメチル基を表し、Ｒ^５１は炭素数１～５の直鎖状または分枝状の炭化水素基を表す。）

(In formula (9), R ⁵⁰ represents hydrogen or a methyl group, and R ⁵¹ represents a linear or branched hydrocarbon group having 1 to 5 carbon atoms.)

When the ratio of the (meth)acrylate structural unit represented by the general formula (9) in the total monomer units in the poly(meth)acrylate polymer exceeds 90 mol%, the solubility in the base oil and the viscosity The effect of improving the temperature characteristics or the low-temperature viscosity characteristics may be inferior, and if the content is less than 10 mol %, the effect of improving the viscosity-temperature characteristics may be inferior.

In this specification, the comb-shaped poly(meth)acrylate is a copolymer of the monomer (M-1) represented by the formula (10) and the monomer (M-2) represented by the formula (11). means a poly(meth)acrylate. In the comb-shaped poly(meth)acrylate, the number average molecular weight of R ¹⁵ in formula (11) is 1,000 or more and 10,000 or less (preferably 1,500 or more and 8,500 or less, more preferably 2,000 or more and 7 ,000 or less).

（式（１０）中、Ｒ^５２は水素原子またはメチル基を表し、Ｒ^５３は炭素数６～１８の直鎖状または分枝状の炭化水素基を表す。）

(In formula (10), R ⁵² represents a hydrogen atom or a methyl group, and R ⁵³ represents a linear or branched hydrocarbon group having 6 to 18 carbon atoms.)

（式（１１）中、Ｒ^５４は水素原子またはメチル基を表し、Ｒ^５５は炭素数１９以上の直鎖状または分枝状の炭化水素基を表す。）

(In formula (11), R ⁵⁴ represents a hydrogen atom or a methyl group, and R ⁵⁵ represents a linear or branched hydrocarbon group having 19 or more carbon atoms.)

As the comb-shaped poly(meth)acrylate, for example, a macromonomer derived from a polyolefin hydride obtained by copolymerizing butadiene and isoprene can be employed.
In the poly(meth)acrylate used in the present invention, the (meth)acrylate structural unit corresponding to the monomer (M-2) represented by general formula (11) in the polymer may be only one type, It may be a combination of two or more. The ratio of structural units corresponding to the monomer (M-2) represented by general formula (11) to all monomer units in the polymer is preferably 0.5 to 70 mol %.

The weight average molecular weight of the viscosity index improver is, for example, 10,000 or more and 1,000,000 or less, preferably 50,000 or more and 900,000 or less, more preferably 100,000 or more and 800,000 or less, further preferably 200,000 or less. 000 or more and 600,000 or less.
When dispersing poly(meth)acrylate and comb-shaped poly(meth)acrylate are used together, the weight-average molecular weight of dispersive poly(meth)acrylate is 100,000 or more and 500,000 or less, and comb-shaped poly(meth)acrylate ) The weight average molecular weight of the acrylate is preferably 300,000 or more and 700,000 or less.

When the lubricating oil composition of the present invention contains a viscosity index improver, the content thereof is appropriately adjusted so that the viscosity index of the lubricating oil composition is preferably 200 or more and 350 or less, more preferably 200 or more and 290 or less. can be adjusted. As used herein, the viscosity index means a viscosity index measured according to JIS K 2283-2000.
When the lubricating oil composition of the present invention contains a viscosity index improver, its content is 1% by mass or more, preferably 5% by mass or more, based on the total amount of the composition. The upper limit is 30% by mass or less, preferably 15% by mass or less. A specific range is 1% by mass or more and 30% by mass or less, preferably 5% by mass or more and 15% by mass or less.

In the present specification, the weight average molecular weight and number average molecular weight of the viscosity index improver mean values determined by gel permeation chromatography (GPC) (molecular weight obtained by polystyrene conversion).

(Other additives)
The lubricating oil composition of the present invention may further contain other additives commonly used in lubricating oils depending on the purpose, in order to further improve its performance. Such additives may include additives such as metallic detergents, dispersants, antioxidants, pour point depressants, and defoamers.

(Metallic detergent)
The lubricating oil composition of the present invention can contain, as metallic detergents, for example, calcium-based detergents, magnesium-based detergents, and/or barium-based detergents. These detergents may be overbased with boric acid, borates, carbonic acid, or carbonates. As the metallic detergent, a metallic detergent having a salicylate group, a metallic detergent having a sulfonate group, or a metallic detergent having a phenate group can be used. It is preferred to use metallic detergents with salicylate groups.

When the lubricating oil composition of the present invention contains a metallic detergent, the specific range of the amount of metal derived from the metallic detergent is based on the total amount of the composition, preferably 200 mass ppm or more and 3000 mass ppm or less, It is more preferably 500 mass ppm or more and 2500 mass ppm or less, and still more preferably 1000 mass ppm or more and 2000 mass ppm or less. In this specification, unless otherwise specified, the content of each element of calcium, magnesium, zinc, boron and phosphorus in oil is measured by inductively coupled plasma atomic emission spectrometry (intensity ratio method (internal standard method)).

(base value)
When the lubricating oil composition of the present invention contains a metallic detergent, the range of base number of the metallic detergent is preferably 150 mgKOH/g or more and 600 mgKOH/g or less, more preferably 200 mgKOH/g or more and 500 mgKOH/g or less. is. In this specification, the base number of the metallic detergent is a value measured according to JIS K 2501:2003-9.

Dispersants include ashless dispersants such as succinimide or benzylamine.
When the lubricating oil composition of the present invention contains a dispersant, its content is usually 10% by mass or less, preferably 0.1% by mass or more, based on the total amount of the composition.

As the antioxidant, a phenol-based ashless antioxidant, an amine-based ashless antioxidant, a molybdenum-based antioxidant, a phosphorus-based antioxidant, or the like can be used.
Examples of phenolic ashless antioxidants include 4,4′-methylenebis(2,6-di-t-butylphenol) and 2,6-di-t-butyl-4-methylphenol.
Aminic ashless antioxidants include alkylated diphenylamine, phenyl-α-naphthylamine, alkylated-α-naphthylamine, bis(nonan-1-ylphenyl)amine, and the like.
Examples of molybdenum-based antioxidants include molybdate dialkylamine salts.
When the lubricating oil composition of the present invention contains these antioxidants, the content thereof is usually 5.0% by mass or less, preferably 3.0% by mass or less, based on the total amount of the composition, and It is preferably 0.1% by mass or more, more preferably 0.5% by mass or more.

As the phosphorus antioxidant, it is preferable to add zinc dialkyldithiophosphate (ZnDTP). Examples of zinc dialkyldithiophosphates include compounds represented by the following general formula (12).

R ⁶⁰ to R ⁶³ in general formula (12) are each independently a linear or branched alkyl group having 1 to 24 carbon atoms. The alkyl group can be primary, secondary or tertiary. The zinc dialkyldithiophosphate is preferably a zinc dithiophosphate having a primary alkyl group (primary ZnDTP) or a zinc dithiophosphate having a secondary alkyl group (secondary ZnDTP). A material containing zinc dithiophosphate as a main component is preferable because it enhances 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. Below, it is more preferably 0.2% by mass or more and 5% by mass or less, and still 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, based on the total amount of the composition, for example, 400 mass ppm or more and 2000 mass ppm or less, preferably 500 mass ppm or more and 1000 mass ppm or less, and further Preferably it is 700 mass ppm or more and 1000 mass ppm or less.

(Lubricating oil composition for internal combustion engine)
The HTHS viscosity at 150° C. of the lubricating oil composition of the present invention is 2.0 mPa·s or more and 3.5 mPa·s or less, preferably 2.2 mPa·s or more and 3.4 mPa·s or less, more preferably 2.5 mPa·s. s or more and 3.2 mPa·s or less. When the HTHS viscosity at 150°C is 3.5 mPa·s or less, good fuel economy performance can be obtained. When the HTHS viscosity at 150°C is 2.0 mPa·s or more, good lubricity can be obtained.
The HTHS viscosity at 150°C indicates the high-temperature high-shear viscosity at 150°C specified in ASTM D4683.

The viscosity index of the lubricating oil composition of the present invention is preferably 200 or more and 350 or less, more preferably 200 or more and 290 or less. When the viscosity index of the lubricating oil composition is 200 or more, the fuel economy performance can be improved while maintaining the HTHS viscosity at 150°C. Moreover, if the viscosity index of the lubricating oil composition exceeds 350, the evaporability may deteriorate.

The kinematic viscosity at 40° C. of the lubricating oil composition of the present invention is preferably 20 mm ² /s or more, more preferably 22 mm ² /s or more, still more preferably 24 mm ² /s or more. The upper limit is preferably 46 mm ² /s or less, more preferably 42 mm ² /s or less, and even more preferably 40 mm ² /s or less. A specific range is preferably 20 mm ² /s or more and 46 mm ² /s or less, more preferably 22 mm ² /s or more and 42 mm ² /s or less, and still more preferably 24 mm ² /s or more and 40 mm ² /s or less. When the kinematic viscosity at 40° C. of the lubricating oil composition is 46 mm ² /s or less, sufficient fuel saving performance can be obtained. In addition, when the kinematic viscosity of the lubricating oil composition at 40° C. is 20 mm ² /s or more, it is possible to ensure the formation of an oil film at the lubricated portion and to reduce the evaporation loss of the lubricating oil composition.
As used herein, "kinematic viscosity at 40°C" means kinematic viscosity at 40°C measured according to ASTM D-445.

The kinematic viscosity at 100° C. of the lubricating oil composition of the present invention is preferably 5.0 mm ² /s or higher, more preferably 7.0 mm ² /s or higher. The upper limit is preferably 12.0 mm ² /s or less, more preferably 10.0 mm ² /s or less. A specific range is preferably 5.0 mm ² /s or more and 12.0 mm ² /s or less, more preferably 7.0 mm ² /s or more and 10.0 mm ² /s or less.

The nitrogen content in the lubricating oil composition of the present invention is preferably 500 mass ppm or more and 1700 mass ppm or less, more preferably 1000 mass ppm or more and 1700 mass ppm or less, based on the total amount of the composition. By setting the nitrogen content to 1700 ppm by mass or less, the corrosion resistance can be further improved.

As used herein, sulfated ash means sulfated ash measured according to ASTM D874. In lubricating oil compositions for internal combustion engines, the higher the amount of metal, the higher the sulfated ash value. Higher sulfated ash values reduce filter life. Therefore, it is preferable to reduce the value of sulfated ash. In the present invention, the amount of sulfated ash is preferably 1.0% by mass or less, more preferably 0.8% by mass or less.

The invention is illustrated below using examples. The present invention is not limited to the following embodiments.

<Combination of lubricating oil>
Lubricating oil compositions for testing were prepared by blending base oils and additives at the blending ratios shown in Tables 1 to 4 for each example and each comparative example. The following evaluations were performed on the obtained lubricating oil composition for test. The evaluation results are shown in Tables 5-8.

(A) Lubricating base oil/lubricating base oil 1: Group III base oil (hydrocracked mineral oil base oil) kinematic viscosity 4.2 mm ² /s (100 ° C.), viscosity index 135
・Lubricating base oil 2: Group II base oil (hydrocracked mineral oil base oil) Kinematic viscosity 3.0 mm ² /s (100 ° C.), viscosity index 106
・Lubricating base oil 3: Group IV base oil (poly-α-olefin) kinematic viscosity 4.1 mm ² /s (100 ° C.), viscosity index 125
Base oils were mixed at the mass ratios shown in Tables 1 to 4 to prepare lubricating base oils. In the table, the numerical value of the base oil represents the mass ratio based on the total amount of the base oil.

Additives were added as described in Tables 1-4. The details of the additive are as follows. The blending amount of the additive is based on the total amount of the composition.
(B) Viscosity index improver/Viscosity index improver 1: comb-shaped poly(meth)acrylate (weight average molecular weight 500,000)
・Viscosity index improver 2: Dispersed poly(meth)acrylate (weight average molecular weight 270,000)
・Viscosity index improver 3: Olefin copolymer (weight average molecular weight 180,000)
(C) Metallic detergent/metallic detergent 1: calcium carbonate salicylate (calcium content: 11.0% by mass, base number: 310 mgKOH/g)
- Metallic detergent 2: calcium carbonate salicylate (calcium content: 8.0% by mass, base number: 230 mgKOH/g)
- Metallic detergent 3: magnesium carbonate salicylate (magnesium content: 7.5% by mass, base number: 350 mgKOH/g)
- Metallic detergent 4: calcium carbonate sulfonate (calcium content: 11.6% by mass, base number: 300 mgKOH/g)
(D) Dispersant/Dispersant 1: Succinimide-based dispersant (boron content 0.0% by mass, nitrogen content 1.5% by mass)
- Dispersant 2: succinimide-based dispersant (boron content of 0.5% by mass, nitrogen content of 1.5% by mass)
(E) Antioxidants/Amine-based ashless antioxidant 1: bis(nonan-1-ylphenyl)amine, nitrogen content of 3.6%
・Phenol-based ashless antioxidant 2: benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, C7-C9 side chain alkyl ester ・Phosphorus-based antioxidant 1: dialkyldithioline zinc acid, zinc content 9.3 wt%, phosphorus content 8.5 wt%, sulfur content 17.8 wt%, secondary ZnDTP
Phosphorus-based antioxidant 2: zinc dialkyldithiophosphate, zinc content 7.8% by mass, phosphorus content 7.0% by mass, sulfur content 14.8% by mass, primary ZnDTP
(F) Organic molybdenum compound/Organic molybdenum compound 1: molybdenum dithiocarbamate (molybdenum content is 10.1% by mass, nitrogen content is 1.5% by mass)
(G) Ashless Friction Modifier/Ashless Friction Modifier 1: N-oleoylsarcosine ((Z)-N-methyl-N-(1-oxo-9-octadecynyl)glycine) with a nitrogen content of 4.0 mass%
Ashless friction modifier 2: glycerin monooleate, nitrogen content of 0.0% by mass
Ashless friction modifier 3: octadecenyl urea, nitrogen content of 9.0 wt%
Ashless friction modifier 4: (Z)-9-octadecen-1-amine, nitrogen content of 5.2% by mass
Ashless friction modifier 5: 2,2′-(octadecen-1-yl imino)diethanol, nitrogen content of 4.1% by weight
(H) Triazole derivative/Triazole derivative 1: N-[(ar-methyl-1H-benzotriazol-1-yl)methyl]bis(2-ethylhexyl)amine (I) Alicyclic epoxy compound/Alicyclic epoxy compound 1: 3,4-epoxycyclohexylmethyl (3,4-epoxy)cyclohexane carboxylate

<Evaluation method>
(1) Amount of sulfated ash The sulfated ash content was measured according to ASTM D874.

(2) HTHS viscosity and viscosity index HTHS viscosity at 150°C was measured according to ASTM D4683.
Also, the viscosity index was measured according to JIS K 2283-1993.

(3) High temperature corrosion bench test (HTCBT)
A high temperature corrosion bench test (HTCBT) was performed according to ASTM D6594. Test lubricants with a copper level of 20 ppm by weight or less, a lead level of 120 ppm by weight or less, and a tin level of 50 ppm by weight or less were rated as having good corrosion resistance.

(4) HTT test (evaluation of cleanliness)
Detergency was measured according to JPI-5S-55-99. The test conditions are a sample amount of 10 mg, a test temperature of 280° C., and a test time of 16 hours. Test lubricants with a rating of 7.0 or higher were rated as having good detergency.

(5) SRV test (evaluation of friction coefficient)
The friction coefficient was measured using an OPTIMOL SRV tester. Cylinders (size φ15×22 mm) and discs (size φ24×6.9 mm), which are standard test pieces conforming to ASTM D5706, D5707 and D6425, were used as test pieces. The test conditions are a load of 100 N, a frequency of 50 Hz, an amplitude of 1.5 mm, a test time of 15 minutes, and a test temperature of 50°C or 80°C. For each coefficient of friction, the average value of the test time of 10 to 15 minutes was adopted. At a test temperature of 50° C., those with a coefficient of friction of 0.075 or less were evaluated as having good fuel economy at low temperatures. At the test temperature of 80° C., those with a coefficient of friction of 0.065 or less were evaluated as having good fuel economy at high temperatures.

The evaluation results for each test lubricating oil composition are shown in Tables 5-8 below.

Each of the test lubricating oil compositions of Examples 1 to 17 exhibited low low-temperature and high-temperature friction coefficient values, and was evaluated as having good fuel economy. In addition, each of the test lubricating oil compositions of Examples 1 to 17 was evaluated to have improved corrosion resistance in HTCBT, with copper, lead, and tin measured values all falling below the specified values.
In Comparative Example 1, which does not contain an alicyclic epoxy compound, the measured value of lead exceeded the specified value in HTCBT.
Comparative Example 2, which does not contain an organomolybdenum compound, has increased low and high temperature friction coefficients.
In Comparative Example 3, which does not contain triazole or a triazole derivative, the measured copper value exceeded the specified value in HTCBT.
In Comparative Example 4, which did not contain an ashless friction modifier, the measured copper exceeded specified values and the low temperature coefficient of friction increased in HTCBT.
In Comparative Example 5, in which an ashless friction modifier was included but the amount of nitrogen derived from the ashless friction modifier exceeded 400 mass ppm, the measured value of lead exceeded the specified value in HTCBT.
In each of Comparative Examples 6 and 7, which contained an organomolybdenum compound but the amount of molybdenum derived from the organomolybdenum compound was less than 400 mass ppm, the low-temperature friction coefficient increased.

According to the lubricating oil composition for internal combustion engines of the present invention, it is possible to provide a lubricating oil composition for internal combustion engines that has improved corrosion resistance while maintaining fuel efficiency at low and high temperatures.

Claims (7)

(A) lubricating base oil,
(B) an organomolybdenum compound,
(C) an alicyclic epoxy compound,
(D) a triazole or triazole derivative, and (E) an amino acid compound, an amine compound, a urea compound, a fatty acid ester compound, and derivatives thereof having an alkyl group, alkenyl group, or acyl group having 12 to 30 carbon atoms. A lubricating oil composition for an internal combustion engine comprising at least one ashless friction modifier comprising
The amount of molybdenum derived from the component (B) is 400 mass ppm or more based on the total amount of the composition,
A lubricating oil composition for an internal combustion engine, wherein the amount of nitrogen derived from the component (E) is 400 mass ppm or less based on the total amount of the composition. 2. The lubricating oil composition for an internal combustion engine according to claim 1, further comprising a poly(meth)acrylate as (F) a viscosity index improver, and having a viscosity index of 200 or more and 350 or less. The lubricating oil composition for internal combustion engines according to claim 1 or 2, wherein the amount of molybdenum derived from said component (B) is 2,000 mass ppm or less based on the total amount of the composition. The lubricating oil composition for internal combustion engines according to any one of claims 1 to 3, wherein the sulfated ash content is 0.8% by mass or less. (A) The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 4, wherein the kinematic viscosity at 100°C of the lubricating base oil is 3.0 mm ² /s or more and 6.0 mm ² /s or less. . (E) The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 5, wherein the ashless friction modifier is a nitrogen-containing ashless friction modifier. (A) the amount of lubricating base oil is 50% by mass or more and 95% by mass or less based on the total amount of the composition;
(C) The amount of the alicyclic epoxy compound is 0.01% by mass or more and 2% by mass or less, based on the total amount of the composition, and (D) The amount of the triazole or triazole derivative is 0, based on the total amount of the composition. The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 6, which is .001% by mass or more and 1% by mass or less.