JPWO2016152540A1 - Lubricating oil composition for internal combustion engine and method for reducing friction of gasoline engine - Google Patents

Abstract

Provided is a lubricating oil composition for an internal combustion engine that can exhibit a sufficient friction reducing effect in a practical temperature range of 80 ° C. or higher from a low temperature range assuming engine startup. A lubricating oil composition for an internal combustion engine, comprising a surfactant having an alkylene oxide as a constituent unit and having an HLB value of 7 or more and less than 15, and a lubricating base oil.

Description

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

In recent years, in order to reduce energy loss and carbon dioxide emission while driving a car, it has been studied to improve the fuel efficiency of the car. As measures for improving the fuel efficiency of automobiles, the weight of automobile bodies is being reduced, but lubricating oils are also required to contribute to the fuel efficiency. For this reason, the improvement of the further friction reduction by lubricating oil is examined.
Patent documents 1-5 are proposed as a technique of friction reduction by lubricating oil.

Patent Document 1 proposes to use a molybdenum-based compound such as MoDTC, which is a typical friction reducing technique, as a friction reducing agent.
Patent Documents 2 and 3 propose using, as a friction reducing agent, an organic compound having a hydroxyl group or an amino group and a boron-containing compound obtained by heating and stirring boric acid or a boric acid derivative in a high-temperature environment. .
Patent Document 4 proposes a lubricating oil composition in which a nonionic surfactant having an HLB value of 15 or more is blended with a lubricating base oil.
Patent Document 5 proposes a lubricating oil composition used for a frictional driving force transmission device containing a specific amine compound.

JP, 2015-010177, A JP 2014-118558 A International Publication 2014/098161 JP 2002-294270 A International Publication 2011/062282

Conventionally, as fuel efficiency of engine oil, it has been common to target fuel efficiency in a temperature range of about 80 to 100 ° C. mainly after the end of warm-up operation of the engine. However, in recent years, there has been a demand for fuel efficiency in a low temperature range of about 25 to 60 ° C. assuming engine start.
However, as in Patent Document 1, just adding a molybdenum friction reducing agent does not provide a friction reducing effect in a low temperature region such as at the time of starting the engine, and the fuel efficiency cannot be sufficiently improved. It was.
The friction reducing agents and lubricating oil compositions proposed in Patent Documents 2 to 5 have not been studied for friction reduction in a low temperature region.

On the other hand, ashless friction reducing agents such as glycerol monooleate have been conventionally used as a method for obtaining a friction reducing effect in a low temperature region. However, such an ashless friction reducing agent cannot obtain a friction reducing effect in a practical temperature range of 80 ° C. or higher.
Currently, a lubricating oil composition for an internal combustion engine is required to have a high friction reducing effect and a low ash differentiation in a practical temperature range of 80 ° C. or higher from a low temperature range at the start of the engine. It is difficult to meet this requirement only by using a molybdenum friction reducer and an ashless friction reducer in combination.
Accordingly, there is a demand for a lubricating oil composition using an ashless friction reducing agent that can provide a sufficient friction reducing effect even in a practical temperature range of 80 ° C. or higher from a low temperature range when the engine is started.

  It is an object of the present invention to provide a lubricating oil composition for an internal combustion engine that can provide a sufficient friction reducing effect not only in a low temperature range assuming engine startup but also in a practical temperature range of 80 ° C. or higher.

  In order to solve the above problems, an embodiment of the present invention provides a lubricating oil composition for an internal combustion engine comprising a surfactant having an alkylene oxide as a structural unit and having an HLB value of 7 or more and less than 15, and a lubricating base oil. provide.

  INDUSTRIAL APPLICABILITY The lubricating oil composition for an internal combustion engine of the present invention can improve the friction reducing effect in a practical temperature range of 80 ° C. or higher from a low temperature range assumed at the time of engine start, and thus can improve fuel economy.

Embodiments of the present invention will be described below.
[Lubricating oil composition for internal combustion engine]
The lubricating oil composition for an internal combustion engine according to the present embodiment includes a surfactant having an alkylene oxide as a constituent unit and having an HLB value of 7 or more and less than 15, and a lubricating base oil.

<Surfactant>
The internal combustion engine lubricating oil composition of the present embodiment includes a surfactant having an alkylene oxide as a structural unit and having an HLB value of 7 or more and less than 15.
Even if the surfactant has an HLB value in the above range, those having no alkylene oxide in the structural unit tend to have insufficient friction reduction. Moreover, even if it is a surfactant which has an alkylene oxide in a structural unit, the thing with an HLB value of less than 7 has bad adsorptivity with respect to a metal surface, and friction reduction is inadequate. Moreover, even if it is surfactant which has an alkylene oxide in a structural unit, a thing with HLB value more than 15 is bad in solubility to a lubricating base oil, and it is very difficult to use it.

As the surfactant, various surfactants can be used. From the viewpoint of reducing friction due to adsorption to the metal surface and stability, an amine compound or amide formed by bonding an alkylene oxide to a nitrogen atom. System compounds and the like are preferred. Among these, amine compounds are preferable, and tertiary amines are preferable among amine compounds.
Examples of the tertiary amine surfactant include compounds represented by the following general formula (I). The compound represented by the general formula (I) is preferable in that the ash content is 0% by mass while having the above effects.

（式中、Ｒ^１及びＲ^２はそれぞれ独立に、炭素数４〜１８のアルキル基、又は炭素数４〜１８のアルケニル基を示す。また、式中、ｘは０又は１を示し、かつｘ＝０の時にｙは１を示し、ｘ＝１の時にｙは０を示す。また、式中、Ａ^１Ｏ及びＡ^２Ｏはそれぞれ独立に、炭素数２〜４のオキシアルキレン基を示す。また、式中、ｎ_１及びｎ_２はオキシアルキレン基の平均付加モル数を示し、それぞれ独立に１〜１３の整数を示し、かつｎ_１＋ｎ_２は５〜１４である。）

(In the formula, R ¹ and R ² each independently represents an alkyl group having 4 to 18 carbon atoms or an alkenyl group having 4 to 18 carbon atoms. In the formula, x represents 0 or 1, and x When y = 0, y represents 1, and when x = 1, y represents 0. In the formula, A ¹ O and A ² O each independently represents an oxyalkylene group having 2 to 4 carbon atoms. in the above formula, _{n 1} and _{n 2} are shown the average addition mole number of oxyalkylene groups, each independently represent an integer of 1 to 13, and _n 1 + _{n 2} is 5-14.)

The alkyl group and alkenyl group of R ¹ and R ² may be linear, branched or cyclic, but is preferably linear. R ¹ and R ² are preferably alkenyl groups. When x = 0, the alkyl group and alkenyl group of R ¹ preferably have 12 to 18 carbon atoms. When x = 1, the alkyl groups and alkenyl groups of R ¹ and R ² preferably have 4 to 16 carbon atoms.

The oxyalkylene group of A ¹ O and A ² O preferably has 2 to 3 carbon atoms, and more preferably 2 carbon atoms.
Further, _{n 1} and _{n 2} is preferably each independently an integer of 2-10, more preferably 3-7. n ₁ + n ₂ is preferably 8 to 12, and more preferably 9 to 11.

In addition, (A ¹ O) _n1 and (A ² O) _n2 may be formed by bonding oxyalkylene groups having different carbon numbers randomly or in blocks. For example, (A ¹ O) _n1 and (A ² O) _n2 may be ones in which an ethylene oxide (EO) group and a propylene oxide (PO) group are bonded randomly or in blocks.

When the tertiary amine of the general formula (I) is used as the surfactant, the same type may be used, or different types may be mixed and used. The same species refers to those in which R ¹ , R ^{2 and the} like in the general formula (I) are all the same. The term “heterologous” refers to a substance in which at least one of R ¹ and R ^{2 in} the general formula (I) is different.
Moreover, even when different types are mixed, it is preferable to include many of the preferred embodiments. For example, the ratio of the mass of the tertiary amine in which R ¹ and R ² are alkenyl groups to the total mass of the tertiary amine of the above general formula (I) [general formula in which R ¹ and R ² are alkenyl groups The mass of the tertiary amine of (I) / the total mass of the general formula (I) tertiary amine] is preferably 60% by mass or more, more preferably 70% by mass or more, and 80% by mass or more. More preferably it is.
From the viewpoint of the stability of the effect, it is preferable to use the tertiary amine of the general formula (I) having the same carbon number for R ¹ . If a tertiary amine of general formula (I) contain an R ^2, it is preferable to further the number of carbon atoms in R ² is used as all the same.

Moreover, as the surfactant, polyoxyalkylene fatty acid esters are also suitable.
The number of carbon atoms of the oxyalkylene group of the polyoxyalkylene fatty acid ester is preferably 2 to 4, more preferably 2 to 3, and still more preferably 2. The oxyalkylene group may be formed by bonding oxyalkylene groups having different carbon numbers randomly or in blocks. Moreover, it is preferable that the average addition mole number of an oxyalkylene group is an integer of 2-10, and it is more preferable that it is 3-7.
The carbon number of the structural unit derived from the fatty acid of the polyoxyalkylene fatty acid ester is preferably 8 to 28, more preferably 14 to 22, and further preferably 16 to 20.
Examples of such polyoxyalkylene fatty acid esters include polyoxyethylene oleate and polyoxyethylene stearate.

The surfactant preferably has a molecular weight in the range of 350 to 950 g / mol, and in the range of 440 to 940 g / mol, from the viewpoint of friction reduction and compatibility between friction reduction and cleanliness. Is more preferable.
In the present embodiment, the molecular weight of the surfactant is measured by a mass spectrum by liquid chromatography mass spectrometry (LC / MS). Specifically, the range in which the peak of the mass-to-charge ratio (m / z) of the surfactant appears was regarded as the range of the molecular weight (g / mol) of the surfactant.
Further, the surfactant preferably has an ash content of 0% by mass.

In this embodiment, it is preferable to contain 0.01-2.0 mass% of the said surfactant in the lubricating oil composition for internal combustion machines, it is more preferable to contain 0.1-1.5 mass%, and 0.2 It is more preferable to contain -1.0 mass%.
By setting the content of the surfactant to 0.01% by mass or more, friction can be reduced in a practical temperature range of 80 ° C. or higher from a low temperature range assumed at the time of engine start. Moreover, by making content of surfactant into 2.0 mass% or less, while maintaining friction reduction, it can be easy to suppress the fall of cleanliness.

<Boron modified product of succinimide>
The lubricating oil composition for an internal combustion machine of the present embodiment preferably further contains a boron-modified product of succinimide.
By containing a boron-modified succinimide together with the above surfactant, friction can be further reduced and cleanliness is improved in a practical temperature range of 80 ° C. or higher from a low temperature range assumed when the engine is started. be able to.

Examples of the boron-modified succinimide include boronated alkenyl or alkyl succinic monoimide, or alkenyl or alkyl succinic bisimide.
Examples of the alkenyl or alkyl succinic acid monoimide include compounds represented by the following general formula (II). Examples of the alkenyl or alkyl succinic acid bisimide include compounds represented by the following general formula (III).

In the general formulas (II) and (III), R ³ , R ⁵ and R ⁶ are alkenyl groups or alkyl groups, and the weight average molecular weights are preferably 500 to 3,000, more preferably 1, respectively. 000 to 3,000.
When the weight average molecular weight of R ³ , R ⁵ and R ⁶ is 500 or more, the solubility in the lubricating base oil can be improved. Moreover, when it is 3,000 or less, it is expected that the effect obtained by the present compound is appropriately exhibited. R ⁵ and R ⁶ may be the same or different.
R ⁴ , R ⁷ and R ⁸ are each an alkylene group having 2 to 5 carbon atoms, and R ⁷ and R ⁸ may be the same or different. n3 represents an integer of 1 to 10, and n4 represents 0 or an integer of 1 to 10. Here, n3 is preferably 2 to 5, more preferably 2 to 4. When n3 is 2 or more, it is expected that the effect obtained by the boron-modified succinimide is easily obtained. When n3 is 5 or less, the solubility in the lubricating base oil is further improved.
In general formula (III), n4 becomes like this. Preferably it is 1-6, More preferably, it is 2-6. When n4 is 1 or more, it is expected that the effect obtained by the present compound is appropriately exhibited. When n4 is 6 or less, the solubility in the lubricating base oil is further improved.

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

The boron-modified succinimide is obtained by, for example, reacting a polyolefin with maleic anhydride to obtain an alkenyl succinic anhydride (A), and further reacting a polyamine with a boron compound to obtain an intermediate (B). Can be obtained by reacting alkenyl succinic anhydride (A) with intermediate (B) and imidizing. Monoimides or bisimides can be made by changing the ratio of alkenyl succinic anhydride or alkyl succinic anhydride to polyamine.
Moreover, the boron modified body of the said succinimide can be manufactured also by processing the alkenyl or alkyl succinic monoimide which does not contain boron, or an alkenyl or alkyl succinic acid bisimide with a boron compound.

As the olefin monomer forming the above-mentioned polyolefin, one or two or more kinds of α-olefins having 2 to 8 carbon atoms can be mixed and used, but a mixture of isobutene and 1-butene is preferably used. be able to.
On the other hand, polyamines include ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, and other single diamines, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di (methylethylene) triamine, dibutylenetriamine, triethylene And polyalkylene polyamines such as butylenetetramine and pentapentylenehexamine, and piperazine derivatives such as aminoethylpiperazine.

Examples of the boron compound include boric acid, borates, and borate esters.
Examples of boric acid include orthoboric acid, metaboric acid, and paraboric acid. Examples of the borate include ammonium borate such as ammonium metaborate, ammonium tetraborate, ammonium pentaborate, and ammonium octaborate. As borate esters, monomethyl borate, dimethyl borate, trimethyl borate, monoethyl borate, diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, Examples thereof include dibutyl borate and tributyl borate.

  From the viewpoint of friction reduction, the ratio of boron atom weight to nitrogen atom weight (B / N ratio) contained in the boron-modified succinimide is preferably 0.6 or more, and 0.7 or more. More preferably, it is 0.8 or more. The B / N ratio is not particularly limited, but is preferably 2.0 or less, more preferably 1.5 or less, and further preferably 1.3 or less.

From the viewpoint of friction reduction, the boron-modified product of the succinimide preferably contains a large amount of tri-coordinated boron-modified product of succinimide, and specifically, a boron-modified product of tri-coordinated succinimide. Is preferably contained in a molar ratio of 0.50 or more, more preferably 0.60 or more, based on the total amount of boron-modified succinimide having three and four coordinates. More preferably, it is 65 or more.
The ratio of the boron-modified body of 3-coordinate succinimide and the boron-modified body of 4-coordinated succinimide can be measured, for example, by ¹¹ B-NMR measurement as a BF ₃ · OEt ₂ standard (0 ppm). In the ¹¹ B-NMR measurement, the peak of the tricoordinated succinimide boron-modified product appears at 5 to 25 ppm, and the peak of the tetracoordinated succinimide boron-modified product appears at -10 to 5 ppm. Therefore, it is possible to calculate the ratio by calculating the integral value of each peak.

  In the present embodiment, the content of the boron-modified succinimide is preferably 0.1 to 15.0% by mass, and 0.2 to 10.0% by mass in the lubricating oil composition for an internal combustion engine. It is more preferable that it is 0.5-5.0 mass%, and it is still more preferable that it is 0.5-2.0 mass%. By making the content of the boron-modified succinimide in the above range, the friction can be further reduced in the practical temperature range of 80 ° C. or higher from the low temperature range assumed at the time of engine start, and the cleanliness is better. It is easy to do.

  Moreover, in this embodiment, it is preferable that content of the boron modified body of the succinimide modified in terms of boron atom is 0.2% by mass or less in the lubricating oil composition for an internal combustion engine, and 0.001 to 0.00. The content is more preferably 05% by mass, and further preferably 0.005 to 0.03% by mass. By setting the content of the boron-modified succinimide in terms of the boron atom in the above range, the friction can be further reduced in a practical temperature range of 80 ° C. or higher from a low temperature range assumed at the time of engine start, and clean. It is easy to make the property better.

  In the present embodiment, the mass ratio of the surfactant content to the boron-modified product content of the succinimide (content of the boron-modified product / content of the surfactant) is 100 or less. Preferably, it is preferably 20 or less, and more preferably 5 or less. By setting the mass ratio in the above range, friction can be further reduced and cleanliness can be easily improved in a practical temperature range of 80 ° C. or higher from a low temperature range assumed when the engine is started.

  Further, in the present embodiment, the content of the surfactant relative to the content in terms of boron atom of the boron-modified product of the succinimide (the content in terms of boron atom of the boron-modified product of the succinimide / the surface activity). The mass ratio of the content of the agent is preferably 1 or less, more preferably 0.2 or less, and even more preferably 0.05 or less. By setting the mass ratio within the above range, friction can be further reduced in a practical temperature range of 80 ° C. or higher from a low temperature range that is assumed when the engine is started, and friction reduction and cleanliness can be more easily achieved.

<Poly (meth) acrylate>
The lubricating oil composition for an internal combustion machine of the present embodiment preferably further contains poly (meth) acrylate as a viscosity index improver.
By containing poly (meth) acrylate, in addition to the improvement in fuel efficiency due to the friction reduction of the surfactant and the boron-modified succinimide, the fuel efficiency can be further improved.

The monomer constituting the poly (meth) acrylate is an alkyl (meth) acrylate, preferably an alkyl (meth) acrylate having a linear alkyl group having 1 to 18 carbon atoms or a branched alkyl group having 3 to 34 carbon atoms.
As preferred monomers constituting the alkyl (meth) acrylate, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, Hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetra (meth) acrylate, hexa (meth) acrylate, octadecyl ( (Meth) acrylate and the like. Two or more of these monomers may be used as a copolymer. The alkyl group of these monomers may be linear or branched.
Examples of the alkyl (meth) acrylate having a branched alkyl group having 3 to 34 carbon atoms include isopropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 3,5,5-trimethylhexyl (meth) acrylate, 2- Butyloctyl (meth) acrylate, 2-hexyldecyl (meth) acrylate, 2-octyldodecyl (meth) acrylate, 2-decyltetradecyl (meth) acrylate, 2-dodecylhexadecyl (meth) acrylate, 2-tetradecyloctadecyl (Meth) acrylate is mentioned.

The poly (meth) acrylate preferably has a weight average molecular weight of 100,000 to 600,000, more preferably 15,000 to 300,000.
In the present embodiment, “weight average molecular weight” refers to a molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC) measurement.

The poly (meth) acrylate preferably has an SSI of 30% or less, more preferably 1 to 28%. By making the said weight average molecular weight into the said range, SSI can be 30% or less.
Here, SSI means the shear stability index (Shear Stability Index), and indicates the ability to resist the decomposition of poly (meth) acrylate. The higher the SSI, the more unstable the polymer is to shear and the easier it is to degrade.

ＳＳＩは、ポリマーに由来するせん断による粘度低下をパーセンテージで示すもので、上記計算式により算出される。式中、Ｋｖ_０は、基油にポリ（メタ）アクリレートを加えた混合物の１００℃動粘度の値である。Ｋｖ₁は、基油にポリ（メタ）アクリレートを加えた混合物を、ＡＳＴＭ Ｄ６２７８の手順にしたがって、３０サイクル高剪断ボッシュ・ディーゼルインジェクターに通過させた後の１００℃動粘度の値である。また、Ｋｖ_oilは、基油の１００℃動粘度の値である。なお、基油としては、１００℃動粘度５．３５ｍｍ^２／ｓ、粘度指数１０５のGroup II基油を使用する。

SSI is a percentage decrease in viscosity due to shear derived from a polymer, and is calculated by the above formula. In the formula, Kv ₀ is a value of 100 ° C. kinematic viscosity of a mixture obtained by adding poly (meth) acrylate to base oil. Kv ₁ is the value of 100 ° C. kinematic viscosity after passing a mixture of base oil plus poly (meth) acrylate through a 30 cycle high shear Bosch diesel injector according to the procedure of ASTM D6278. Kv _oil is the value of the 100 ° C. kinematic viscosity of the base oil. As a base oil, a Group II base oil having a kinematic viscosity of 100 ° C. of 5.35 mm ² / s and a viscosity index of 105 is used.

  The content of the poly (meth) acrylate is preferably 1 to 15% by mass, more preferably 2 to 10% by mass in the lubricating oil composition for an internal combustion engine from the viewpoint of fuel economy. More preferably, it is 8 mass%.

<Molybdenum compound>
The lubricating oil composition for an internal combustion machine of the present embodiment preferably further contains a molybdenum compound from the viewpoint of reducing friction.
Examples of the molybdenum compound include MoDTC (molybdenum dialkyldithiocarbamate) and MoDTP (molybdenum dialkyldithiophosphate).
The content of the molybdenum compound is preferably 2.0% by mass or less, more preferably 0.1 to 1.0% by mass in the lubricating oil composition for internal combustion machines.

<Lubricant base oil>
Examples of the lubricating base oil include mineral oil and / or synthetic oil.
Mineral oils include paraffin-based mineral oils, intermediate-based mineral oils and naphthenic-based mineral oils obtained by ordinary refining methods such as solvent refining and hydrogenation refining; wax produced by the Fischer-Tropsch process (gas-tri-liquid wax) And wax isomerized oil produced by isomerizing wax such as mineral oil-based wax.
Examples of synthetic oils include hydrocarbon synthetic oils and ether synthetic oils. Examples of the hydrocarbon-based synthetic oil include polybutene, polyisobutylene, 1-octene oligomer, 1-decene oligomer, α-olefin oligomer such as ethylene-propylene copolymer or the hydride thereof, alkylbenzene, and alkylnaphthalene. . Examples of ether synthetic oils include polyoxyalkylene glycol and polyphenyl ether.

The lubricating base oil may be a single system using one of the above-mentioned mineral oils and synthetic oils, but is a mixture of two or more mineral oils or a mixture of two or more synthetic oils. A mixed system may be used, such as a mixture of one or more of mineral oil and synthetic oil.
In particular, as the lubricating base oil, it is preferable to use one or more selected from mineral oils or synthetic oils classified into Group 3 and Group 4 in the base oil classification of the American Petroleum Institute.

  The content of the lubricating base oil is preferably 70% by mass or more and less than 100% by mass, more preferably 75% by mass or more and 95% by mass or less, and more preferably 80% by mass or more in the lubricating oil composition for an internal combustion engine. More preferably, it is 90 mass% or less.

<Additives>
The internal combustion engine lubricating oil composition of the present embodiment may contain additives such as metal detergents, antioxidants, and antiwear agents.
The content of these additives is preferably 0.01 to 5% by mass with respect to the total amount of the lubricating oil composition for an internal combustion machine.

<Physical properties of lubricating oil composition for internal combustion engine>
The lubricating oil composition for an internal combustion engine of the present embodiment has a 40 ° C. kinematic viscosity, a 100 ° C. kinematic viscosity, and a 150 ° C. HTHS viscosity from the viewpoint of reducing friction in a practical temperature range of 80 ° C. or higher from a low temperature range assuming engine starting. Are preferably in the following ranges, respectively.
The 40 ° C. kinematic viscosity is preferably 20 to 40 mm ² / s, and more preferably 30 to 35 mm ² / s.
100 ° C. kinematic viscosity is preferably 3.0~12.5mm ² / s, more preferably 4.0~9.3mm ² / s.
The 150 ° C. HTHS viscosity is preferably 1.4 to 2.9 mPa · s, and more preferably 1.7 to 2.9 mPa · s.
The kinematic viscosity was measured according to JIS K2283. The HTHS viscosity was measured according to ASTM D4683 using a TBS viscometer (Tapered Bearing Simulator Viscometer), oil temperature 100 ° C., shear rate 10 ⁶ / s, rotation speed (motor) 3000 rpm, interval (rotor and stator The interval was measured under the condition of 3 μm.

<Use of lubricating oil composition for internal combustion machine>
The lubricating oil composition for an internal combustion engine of the present embodiment can be suitably used for various internal combustion engines such as a four-wheeled vehicle and a two-wheeled vehicle. Moreover, among internal combustion engines, it can be particularly suitably used for gasoline engines.

[Method for reducing friction of internal combustion engine]
The internal combustion engine friction reducing method of the present embodiment is a method in which the above-described lubricating oil composition for an internal combustion engine of the present embodiment is added to the internal combustion engine.
According to the friction reduction method for an internal combustion engine of the present embodiment, the friction reduction effect can be improved in a practical temperature range of 80 ° C. or higher from a low temperature range assumed at the time of engine start, and thus fuel economy is improved. Can be. When the internal combustion engine is a gasoline engine, the effect can be made particularly good.

  Next, the present embodiment will be described in more detail by way of examples.

1. Preparation of Lubricating Oil Composition for Internal Combustion Machines Lubricating oil compositions for internal combustion machines of Examples, Comparative Examples, and Reference Examples were prepared at the composition ratios shown in Table 1. The lubricating oil compositions for internal combustion engines of the examples, comparative examples, and reference examples are all prepared by adjusting the HTHS viscosity at 150 ° C. to 2.6 mPa · s.

2. Measurement and Evaluation The following measurements and evaluations were performed on the lubricating oil compositions for internal combustion engines of Examples, Comparative Examples, and Reference Examples. The results are shown in Table 1.
2-1. Kinematic Viscosity According to the description in the specification, the 40 ° C. kinematic viscosity and 100 ° C. kinematic viscosity of the lubricating oil composition for an internal combustion engine were measured.

2-2. Coefficient of friction The coefficient of friction of the lubricating oil composition for internal combustion machines was measured under the following conditions.
Test machine: MTM (Mini Traction Machine) test machine, PCS Instruments manufactured test piece: Standard test piece rubbing (run-in) time: 2 hours Oil temperature: 80 ° C
Load: 10N
Measurement speed: 1.2 m / s

The materials in Table 1 are as follows.
<Lubricant base oil>
Mineral oil having a kinematic viscosity of 100 ° C. of 4.07 mm ² / s, viscosity index: 131,% C _A : −0.4,% C _N : 12.8,% C _P : 87.6
<Surfactant A>
A tertiary amine of the general formula (I) (x = 0, n1 + n2 = 10, carbon number of A ¹ O and A ² O: 2, R ¹ : oleyl group) 69% by mass, and a tertiary amine of the general formula (I) Mixture with tertiary amine (x = 0, n1 + n2 = 10, carbon number of A ¹ O and A ² O: 2, R ¹ : stearyl group) 31% by mass (mass ratio is measured by liquid chromatography mass spectrometry) . HLB value: 13.2. Peak appearance position of mass spectrum by liquid chromatography mass spectrometry: 440 to 940 m / z (≈molecular weight range: 440 to 940 g / mol).
Liquid chromatograph mass spectrometry was performed under the following conditions.
<Conditions for high performance liquid chromatography-mass spectrometry>
・ Detector: Photodiode array detector, evaporative light scattering detector ・ Column: Inertsil ODS (3.0 × 150 mm, 3 μm)
Mobile phase: A) MeCN / (0.1% formic acid + 0.1% ammonium formate) = 80/20
B) THF
-Mass spectrometry: Ion Trap MS manufactured by Thermo Fisher Scientific
-Ion source: Heated ESI positive, negative
M / z range: 150-1000
<Surfactant B>
A tertiary amine of general formula (I) (x = 0, n1 + n2 = 7, carbon number of A ¹ O and A ² O: 2, R ¹ : oleyl group) 85% by mass, and a tertiary amine of general formula (I) A mixture with tertiary amine (x = 0, n1 + n2 = 10, carbon number of A ¹ O and A ² O: 2, R ¹ : stearyl group) with 15% by mass (mass ratio is measured by liquid chromatography mass spectrometry) . HLB value: 11.7. Peak appearance position of mass spectrum by liquid chromatography mass spectrometry: 400 to 850 m / z (≈molecular weight range: 400 to 850 g / mol).
<Surfactant C>
Polyoxyalkylene fatty acid ester (HLB value: 11.1, carbon number of oxyalkylene group: 2, average number of added moles of oxyalkylene group: 5, carbon number of structural unit derived from fatty acid: 18)
<Surfactant D>
Product name: Esomine O / 12, manufactured by Lion Akzo, Material name: Polyoxyethylene oleylamine (tertiary amine of general formula (I), x = 0, n1 + n2 = 2, carbon number of A ¹ O and A ² O : 2), HLB value 6.5, weight average molecular weight: 356
<Surfactant E>
Product name: INFINEUM-C9440, manufactured by Infinium, substance name: glycerol monooleate

<Boron modified product of succinimide>
Boron modified polybutenyl succinic acid bisimide, ratio of tetracoordinate and tricoordinate (integral value of tricoordinate peak / integral value of tetracoordinate peak + integral value of tricoordinate peak): 0. 67, boron atomic weight / nitrogen atomic weight: 1.1, boron content: 1.30% by mass, nitrogen content: 1.23% by mass
<MoDTC>
MoDTC with Mo content of 0.07% by mass
<Polymethacrylate>
Weight average molecular weight: 230,000, SSI: 25.2%
<Metal-based detergent>
Calcium salicylate, calcium content: 7.8% by mass, overbased, base number 224 mgKOH / g
<Antioxidant>
Phenol-based antioxidant, trade name: IRGANOX-L135, manufactured by BASF <Package additive>
Package additive containing ZnDTP, polymer bisimide, amine antioxidant <other additives>
Metal deactivator, pour point depressant

  From the results of Table 1, it can be confirmed that the lubricating oil compositions for internal combustion engines of Examples 1 to 4 are excellent in the friction reducing effect in a practical temperature range of 80 ° C. or higher while using an ashless friction reducing agent. . In particular, the lubricating oil composition for an internal combustion engine of Example 3 comprising a combination of a surfactant having an alkylene oxide as a constituent unit and having an HLB value of 7 or more and less than 15 and a boron-modified succinimide, It can be confirmed that the effect is extremely excellent.

2-3. Cleanliness The cleanliness of the lubricating oil compositions for internal combustion engines of Examples 1 and 3, Comparative Examples 1 to 3, and Reference Example was further evaluated.
<Score>
The test temperature was set to 300 ° C., and the other conditions were measured according to JPI-5S-55-99. Based on JPI-5S-55-99, the glass tube after the test was evaluated in increments of 0.5 at 0 points (black) to 10 points (colorless), and evaluated in 21 steps. The higher the number, the better the cleanliness.
<Adhesion amount>
In the above test of the score, the mass of the lacquer adhered to the glass tube after the test was measured. The smaller the amount of adhesion, the better the cleanliness.

表２の結果から、アルキレンオキサイドを構成単位に有し、かつＨＬＢ値７以上１５未満である界面活性剤と、コハク酸イミドのホウ素変性体とを併用してなる実施例３の内燃機用潤滑油組成物は、さらに清浄性を良好にできることが確認できる。

From the results of Table 2, the lubricating oil for an internal combustion engine of Example 3 comprising a combination of a surfactant having an alkylene oxide as a constituent unit and having an HLB value of 7 or more and less than 15 and a boron-modified succinimide. It can be confirmed that the composition can be further improved in cleanliness.

  The lubricating oil composition for an internal combustion engine of the present embodiment utilizes the characteristics that friction can be reduced and fuel economy can be improved in a practical temperature range of 80 ° C. or higher from a low temperature range assumed when the engine is started. It can be suitably used for various internal combustion engines such as wheel cars and two-wheeled cars. Moreover, among internal combustion engines, it can be particularly suitably used for gasoline engines.

Claims (15)

  A lubricating oil composition for an internal combustion engine, comprising a surfactant having an alkylene oxide as a structural unit and having an HLB value of 7 or more and less than 15, and a lubricating base oil.   The lubricating oil composition for an internal combustion engine according to claim 1, wherein the surfactant has a molecular weight in the range of 350 to 950 g / mol.   The lubricating oil composition for an internal combustion engine according to claim 1 or 2, wherein the surfactant is an amine compound.   The lubricating oil composition for an internal combustion engine according to claim 3, wherein the amine compound is a tertiary amine.   The lubricating oil composition for internal combustion engines according to claim 1 or 2, wherein the surfactant is a polyoxyalkylene fatty acid ester.   The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 5, wherein a content of the surfactant in the lubricating oil composition is 0.01 to 2.0 mass%.   Furthermore, the lubricating oil composition for internal combustion engines of any one of Claims 1-6 containing the boron modified body of a succinimide.   The lubricating oil composition for an internal combustion engine according to claim 7, wherein the boron-modified content of the succinimide boron-modified product in the lubricating oil composition is 0.2% by mass or less.   The mass ratio of the content of the surfactant to the content of the boron-modified product of the succinimide (the content of the boron-modified product of the succinimide / the content of the surfactant) is 100 or less. Item 9. The lubricating oil composition for internal combustion engines according to Item 7 or 8.   The content of the surfactant relative to the boron atom content of the boron-modified product of the succinimide (content of boron atom of the boron-modified product of succinimide / content of the surfactant) The lubricating oil composition for an internal combustion engine according to any one of claims 7 to 9, wherein the ratio is 20 or less.   Furthermore, the lubricating oil composition for internal combustion engines of any one of Claims 1-10 containing a poly (meth) acrylate.   The said lubricating base oil is 1 or more types chosen from the mineral oil or synthetic oil classified into the group 3 and the group 4 in the base oil classification | category of the American Petroleum Institute of Claim 1-11. Lubricating oil composition for internal combustion engines. The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 12, wherein the kinematic viscosity at 100 ° C is 3.8 to 12.5 mm ² / s.   The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 13, which is used for a gasoline engine.   A method for reducing friction in a gasoline engine, wherein the lubricating oil composition for an internal combustion engine according to any one of claims 1 to 13 is added to the gasoline engine.