JP6072605B2 - Lubricating oil composition for internal combustion engines - Google Patents

Description

  The present invention is a lubricating oil for an internal combustion engine in which a monoglyceride (partial ester of fatty acid and glycerin) is blended as a friction modifier in order to realize fuel saving performance in an internal combustion engine (hereinafter sometimes referred to as an engine). A fuel-saving automotive engine oil lubricating oil composition with excellent performance to prevent engine corrosion and rust by dispersing condensed water due to water vapor generated by the combustion of fuel in an internal combustion engine into the engine oil About.

  In recent passenger cars, an idling stop function is activated when the passenger car is stopped by a signal or the like in order to suppress the fuel consumption of the engine, and the engine is frequently stopped during traveling in an urban area. For this reason, in short-distance driving such as shopping, the temperature of the lubricating oil for the internal combustion engine does not rise sufficiently, and the operation ends before the water mixed in the oil evaporates and is discharged in the oil pan. End up. Similarly, in a PHV (Plug-in-Hybrid) vehicle, etc., the engine does not get warm enough when driving commuting or shopping at a short distance due to on-off of the engine rotation as required. In order to stop, the water vapor generated by the combustion of the fuel enters the engine room together with the blow-by gas, and since the engine is not warmed, it may condense in the oil pan to form water droplets and be mixed into the lubricating oil for the internal combustion engine.

Furthermore, in recent years, from the viewpoint of CO ₂ reduction of global warming, while renewable biofuels is applied to automotive gasoline and diesel.

For example, based on Japan's Energy Supply Structure Advancement Law, plans are underway to reduce greenhouse gas (CO ₂ ) annually by blending these renewable biofuels with gasoline for automobiles. Actually, 210,000 KL / year of biofuel in crude oil equivalent was applied to automobile gasoline in 2010, and 500,000 KL / year of biofuel in crude oil equivalent will be applied by FY2017. It is planned.

These biofuels, specifically, bioethanol or bio ETBE (Ethyl tert-butyl ether) have a hydrogen element ratio (H / C) among the hydrocarbons used in the fuel. It is a high fuel for internal combustion engines, and more water (steam) is generated during combustion than ordinary fuel. H / C (carbon hydrogen ratio) of commercially available premium gasoline and regular gasoline is 1.763 and 1.875, respectively, when calculated from the carbon concentration in Table 2.4-1 of Non-Patent Document 1. If 3% of this premium gasoline and regular gasoline are replaced with (bio) ethanol or the like, the H / C will be approximately 1.80 and 1.91, respectively. Thus, by applying biofuel to gasoline, H / C is increased and CO ₂ due to combustion is reduced, but the generation of water vapor is increased. Similarly, according to Table 4.1.1-2 of Non-Patent Document 2, H / C of commercially available diesel oil equivalent “BASE” is 1.91 as H / C of commercially available diesel oil. According to Table 2 of Patent Document 3, H / C of diesel diesel oil JIS2 is 1.927, and when 5% of these are replaced with methyl stearate as a representative biofuel for diesel engine blending, H / C is Although it increases to about 1.93, the generation of CO ₂ due to combustion decreases, while the generation of water vapor increases.

  The same applies to engines for vehicles that use natural gas, LPG, or propane, which have a higher hydrogen element ratio (H / C) than gasoline or light oil, as fuel.

  According to the latest gasoline engine oil standards, API-SN + RC (Resource Conserving) and ILSAC GF-5 standards, combustion water and unburned ethanol are also used for internal combustion engines even for vehicles using E85 fuel containing bioethanol. The ability to emulsify (condensate) water or E85 fuel into the internal combustion engine oil so that water drops do not precipitate on the metal surface and rust or corrode from the surroundings (ASTM D7563). : Emulsion Retention) is required, and these performances are standardized. Emulsion retention (emulsion retention: emulsion stability) is a test whose evaluation method is defined in ASTM D7563. This test was conducted in the form of an emulsion without depositing on the surface of the internal combustion engine oil to be used so that even if (condensation) water, E85 fuel, etc. were mixed, the internal combustion engine parts of each part would not rust or corrode. It is a test to confirm and evaluate the stability of the oil in the oil and whether it is separated or not.

  On the other hand, in recent years, ashless friction modifiers such as fatty acid esters have been added to lubricating oil for internal combustion engines in order to reduce inter-metal friction in internal combustion engines and improve fuel economy. (For example, see Patent Document 1 and Non-Patent Document 4).

  Although organic molybdenum compounds are often used as friction modifiers, they do not adversely affect exhaust gas treatment equipment such as exhaust gas catalysts and diesel particulate filters (DPF), and have little impact on the environment. In recent years, ashless-based friction modifiers (which do not contain elements such as metal and phosphorus, and thus do not generate ash when burned) are preferred.

  The ashless friction modifiers added to these lubricating oils for internal combustion engines do not contain elements such as metals and phosphorus, so there is little effect on exhaust gas catalysts and exhaust gas aftertreatment systems, and lubrication for internal combustion engines. It is known to be easy to apply to oil. On the other hand, in order to have an effect as a surfactant, in some cases, the demulsibility and water separation properties of internal combustion engine oil become stronger, and when condensed water of water vapor generated by fuel combustion is mixed in the oil, Water easily deposits on the metal surfaces of engine parts. Since the precipitated water contains oxidized combustion residues, there has been a concern that rust and corrosion will be caused on the metal surfaces of engine parts.

  In particular, monoglyceride ashless friction modifiers are known to have a high friction reducing effect and are suitable for lubricating oil compositions for internal combustion engines. When the condensed water of water vapor is mixed into the engine oil, there has been a concern about improving the demulsibility and water separation.

  From the above, it has excellent wear resistance and fuel efficiency (low friction characteristics), and also condensates water caused by water vapor generated by fuel combustion, etc., in oil to prevent corrosion and rust of the internal combustion engine. There is a need for lubricating oil compositions for internal combustion engines that have the ability to

JP 2004-155881 A

Japan Petroleum Industry Revitalization Center: FY2005 Automotive Fuel Research Results Report PEC-2005JC-16, 2-14 Japan Petroleum Industry Revitalization Center: FY2008 Research and Development Results Report on Diversification and Highly Efficient Use of Automobile Fuels 14 National Institute for Traffic Safety and Environment Forum 2011 Materials Trends in Advanced Fuels for Automobiles at the International Energy Agency (IEA) Tribologist, Naoto Namiki, Vol. 48, No. 11 (2003), 903-909

  The present invention has been made in view of such a situation, and the object thereof is to have excellent wear resistance and fuel saving, and to condense water caused by water vapor generated by combustion of fuel into oil. An object of the present invention is to provide a lubricating oil composition for an internal combustion engine which has a performance of dispersing and preventing corrosion and rust of the internal combustion engine.

The inventors have identified specific internal combustion engine lubricating oils {particularly in groups 2, 3 and 4 in the base oil category of API (American Petroleum Institute) with a kinematic viscosity at 100 ° C. of 3.0 to 12.0 mm ² / s. In at least one or more base oils selected from the group consisting of base oils classified into (1), the anti-emulsifying properties and water separation properties of monoglycerides having a specific structure used as ashless friction modifiers were confirmed. As a result, when a specific amount of monoglyceride having the specific structure is contained, excellent friction resistance and the like can be exhibited. However, when condensed water of steam accompanying combustion of engine fuel is mixed into engine oil, It has been clarified that the demulsibility and water separability are enhanced by the relationship with the lubricating oil for internal combustion engines, and water can be easily separated from the surface (a trade-off relationship). For this reason, when the monoglyceride having the specific structure is used alone, rust prevention and corrosion resistance are reduced, and the above-mentioned specific internal combustion engine lubricating oil composition containing the monoglyceride having the specific structure is the latest gasoline. It became clear that the engine oil standards API-SN + RC and ILSAC GF-5 were not met.

  Therefore, the present inventors have conducted various studies and studies in order to improve the emulsion stability of the above-described composition (that is, a combination of a specific base oil and a specific amount of a monoglyceride having a specific structure). As a result, the lubricating oil for an internal combustion engine in which a fatty acid ester having an HLB value of 1.0 to 4.0 or a fatty acid ester derivative obtained by adding polyoxyethylene to the fatty acid ester is blended in a predetermined range has excellent wear resistance. The present invention has been completed by finding that the emulsion stability is improved while exhibiting the properties and fuel economy.

More specifically, the present invention provides the following [1] to [4].
The present invention [1]
(A) Kinematic viscosity at 100 ° C. is 3.0 to 12.0 mm ² / s, and selected from the group consisting of base oils classified into groups 2, 3 and 4 in the API (American Petroleum Institute) base oil category At least one base oil, and
(B) A monoglyceride having a hydrocarbon group having 8 to 22 carbon atoms and a hydroxyl value of 150 to 350 mgKOH / g is 0.3 to 2.0% by mass based on the total amount of the composition,
(C) A fatty acid ester having an HLB value of 1.0 to 4.0, or a fatty acid ester derivative obtained by adding polyoxyethylene to the fatty acid ester, 0.7% by mass or more based on the total amount of the composition,
It is a lubricating oil composition for internal combustion engines characterized by containing.
The present invention [2] is an internal combustion engine using a fuel having an H / C ratio of 1.75 to 4, an internal combustion engine of a vehicle with an idling stop device, or an internal combustion using a fuel blended with biofuel. The lubricating oil composition for an internal combustion engine according to the invention [1], wherein the lubricating oil composition is used in an engine.
The invention [3] is the lubricating oil composition for internal combustion engines according to the invention [1] or [2], wherein the fatty acid ester is a sorbitan fatty acid ester.
The invention [4] is the lubricating oil composition for internal combustion engines according to any one of the inventions [1] to [3], wherein the fatty acid ester is a fatty acid triester.

  According to the present invention, it has excellent wear resistance and fuel economy, and also condensates water caused by water vapor generated by fuel combustion or the like in oil so as to form a stable emulsion, thereby preventing corrosion of an internal combustion engine. A lubricating oil composition for internal combustion engines having the ability to prevent rust is obtained.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In addition, this form is one form of this invention to the last, and the technical scope of this invention is not limited to this form.

The lubricating oil composition for internal combustion engines according to this embodiment will be described in the following order.
1 Lubricating Oil Composition-Composition 2 Lubricating Oil Composition-Properties 3 Lubricating Oil Composition-Applications

This form
(A) Kinematic viscosity at 100 ° C. is 3.0 to 12.0 mm ² / s, and selected from the group consisting of base oils classified into groups 2, 3 and 4 in the API (American Petroleum Institute) base oil category At least one base oil, and
(B) A monoglyceride having a hydrocarbon group having 8 to 22 carbon atoms and a hydroxyl value of 150 to 350 mgKOH / g is 0.3 to 2.0% by mass based on the total amount of the composition,
(C) A fatty acid ester having an HLB value of 1.0 to 4.0, or a fatty acid ester derivative obtained by adding polyoxyethylene to the fatty acid ester, 0.7% by mass or more based on the total amount of the composition,
It is related with the lubricating oil composition for internal combustion engines characterized by containing.

≪Lubricating oil composition-composition≫
The lubricating oil composition for internal combustion engines according to this embodiment (hereinafter sometimes simply referred to as “lubricating oil composition”) includes, as its components, base oil, monoglyceride, fatty acid ester or derivative thereof, and necessary And other additives. Each component will be described in detail below.

<Base oil>
As the base oil of the present lubricating oil composition, mineral oils and hydrocarbon synthetic oils called highly refined base oils can be used. Particularly, group 2 in the API (American Petroleum Institute, American Petroleum Institute) base oil category, Base oils selected from the group consisting of base oils classified into Group 3 and Group 4 can be used alone or as a mixture. The base oil used here has a kinematic viscosity at 100 ° C. of 3.0 to 12.0 mm ² / s, preferably 3.0 to 10.0 mm ² / s, more preferably 3.0 to It may be 8.0 mm ² / s. The viscosity index of the base oil may be 100 to 180, preferably 100 to 160, more preferably 100 to 150. The sulfur element content of the base oil may be 300 ppm or less, preferably 200 ppm or less, more preferably 100 ppm or less, and even more preferably 50 ppm or less. The density of the base oil at 15 ° C. is 0.80 to 0.95 g / cm ³ , preferably 0.80 to 0.90 g / cm ³ , more preferably 0.80 to 0.85 g / cm ^3. Also good. The aromatic content% C _{A of the} base oil (the aromatic content in the present invention is ndM analysis: measured by ASTM D3238) may be less than 5, preferably less than 4, more preferably less than 3.

Group 2 base oils are, for example, paraffinic mineral oils obtained by applying a suitable combination of hydrocracking, dewaxing and other refining means to a lubricating oil fraction obtained by distillation of crude oil under reduced pressure. Can be mentioned. Also, the base oil of the Gulf Company Law Group 2, which is refined by hydrorefining methods such as, together with the total sulfur content is less than 10 ppm, aromatic content% C _A is 5 or less, the lubricating oil composition of the present embodiment It can be suitably used as a base oil blended into a product. Group 2 base oils preferably have a viscosity index (the viscosity index in the present invention is measured by ASTM D2270 and JIS K2283) of 100 or more and less than 120, and more preferably 105 or more and less than 120. The kinematic viscosity at 100 ° C. of the base oil of group 2 (the kinematic viscosity in the present invention is measured by ASTM D445 and JIS K2283) is preferably 3.0 to 12.0 mm ² / s, and preferably 3.0 to 9 More preferably, it is 0.0 mm ² / s. The group 2 base oils preferably have a total sulfur content of less than 300 ppm, more preferably less than 200 ppm, even more preferably less than 100 ppm, and particularly preferably less than 10 ppm. The total sulfur content is a value measured using a radiation excitation method (according to ASTM D4294, JIS K2541-4). The total nitrogen content of the Group 2 base oil may be less than 10 ppm, preferably less than 1 ppm. Further, the aniline point of the group 2 base oil (aniline point in the present invention is measured by ASTM D611, JIS K2256) is preferably 80 to 150 ° C, and more preferably 100 to 135 ° C.

Group 3 base oils include, for example, “paraffinic mineral oil obtained by applying advanced hydrorefining means to lubricating oil fraction obtained by distillation of crude oil under reduced pressure”, “natural gas liquid GTL (gas-liquid) wax synthesized by the Fischer-Tropsch method, which is a fuel technology, or wax produced via a dewaxing process is further converted to isoparaffin and dewaxed after solvent dewaxing Examples of the base oil refined by the ISODEWAX process, the base oil refined by the mobile wax (WAX) isomerization process, and the like. The viscosity index of Group 3 base oils is preferably 100 to 150, more preferably 100 to 140. Kinematic viscosity at 100 ° C. of the base oil group 3 is preferably 3.0~12.0mm ² / s, more preferably 3.0~9.0mm ² / s. Further, the total sulfur content of the Group 3 base oils is preferably less than 100 ppm, and more preferably less than 10 ppm. The total nitrogen content of Group 3 base oils is preferably less than 10 ppm, more preferably less than 1 ppm. Furthermore, the aniline point of the group 3 base oil is preferably 80 to 150 ° C, more preferably 110 to 140 ° C.

  Group 4 base oils include polyalphaolefins (poly-α-olefins), alpha olefin oligomers (α-olefin oligomers), or mixtures thereof (polyalphaolefins and alpha olefin oligomers). Polyalphaolefin (PAO) is a polymer of various alphaolefins (monomers). The polyalphaolefin may be a mixture of not only one “alpha olefin (monomer) polymer” but also a plurality of “alpha olefin (monomer) polymer”. The alpha olefin oligomers are oligomers of various alpha olefins (monomers), and also include hydrogenated alpha olefin (monomer) oligomers. Although it does not specifically limit as an alpha olefin (monomer), For example, ethylene, propylene, butene, an alpha olefin of 5 or more carbon atoms, etc. are mentioned.

In addition, GTL (Gas Liquid Liquid) oil synthesized by the Fischer-Tropsch method of natural gas liquid fuel technology has extremely low sulfur and aromatic content compared to mineral oil base oil refined from crude oil. Since the paraffin composition ratio is extremely high, the oxidation stability is excellent, and the evaporation loss is very small. Therefore, it is suitable as the base oil of this embodiment. The viscosity property of the GTL base oil is not particularly limited, but the viscosity index is preferably 100 to 180, and more preferably 100 to 150. Further, the kinematic viscosity at 100 ° C., is preferably 3.0~12.0mm ² / s, and further preferably from 3.0~9.0mm ² / s.

  In general, the total sulfur content may be less than 10 ppm and the total nitrogen content may be less than 1 ppm. An example of such a GTL base oil product is SHELL XHVI (registered trademark).

  Examples of the hydrocarbon-based synthetic oil include polyolefins including PAO described above, alkylbenzene, alkylnaphthalene, and the like, or a mixture thereof.

The viscosity of these synthetic oils is not particularly limited, the kinematic viscosity at 100 ° C., is preferably 3.0~12.0mm ² / s, more to be 3.0~10.0mm ² / s Preferably, it is 3.0-8.0 mm < ² > / s. The viscosity index of the synthetic base oil is preferably 10 to 120 in the case of alkylbenzene or alkylnaphthalene, more preferably 20 to 120, still more preferably 20 to 110, and polyalphaolefin. Is preferably 100 to 170, more preferably 110 to 170, and still more preferably 110 to 155. Density at 15 ℃ of the synthetic base oil is preferably 0.8000~0.9500g / cm ^3, more preferably 0.8100~0.9500g / cm ^3, 0.8100~0. More preferably, it is 9200 g / cm ³ .

Furthermore, as the base oil of the lubricating oil composition, a base oil belonging to Group 1 in the API (American Petroleum Institute, American Petroleum Institute) base oil category may be blended with the base oil. Group 1 base oils can be obtained, for example, by applying a suitable combination of solvent refining, hydrorefining, dewaxing and other refining means to a lubricating oil fraction obtained by atmospheric distillation of crude oil. Mention may be made of paraffinic mineral oil. The group 1 base oil used here has a kinematic viscosity at 100 ° C. of 3.0 to 12.0 mm ² / s, preferably 3.0 to 10.0 mm ² / s, more preferably 3.0 to 8. It may be 0 mm ² / s. Further, the viscosity index may be 90 to 120, preferably 95 to 115, more preferably 95 to 110. Further, the sulfur content may be 0.03 to 0.7% by mass, preferably 0.1 to 0.7% by mass, more preferably 0.4 to 0.7% by mass. Moreover,% CA by ASTM D3238 may be 5 or less, preferably 4 or less, more preferably 3.4 or less. Also, the% CP according to ASTM D3238 may be 60 or more, preferably 63 or more, more preferably 66 or more.

  The content of the base oil in the lubricating oil composition of the present embodiment is not particularly limited, but is 50 to 90% by mass, preferably 60 to 90% by mass, more preferably 70 to 85% by mass based on the total amount of the lubricating oil composition. The range of can be illustrated. In addition, when mix | blending the base oil which belongs to Group 1 as a base oil of this lubricating oil composition, Preferably the range of 10 mass% or less can be illustrated on the basis of the whole quantity of lubricating oil composition. By making the base oil belonging to Group 1 within the range, the influence on the wear resistance and friction reduction effect of the lubricating oil composition is reduced.

<Monoglyceride>
The monoglyceride used as the ashless friction modifier is a partial ester of a fatty acid and glycerin, more specifically, a glycerin fatty acid ester in which a fatty acid is ester-bonded to one of the three hydroxyl groups of glycerin. The monoglyceride according to the form may contain some diglycerides (glycerin fatty acid esters in which fatty acids are ester-bonded to two of the three hydroxyl groups of glycerin) as impurities)}. In this embodiment, the hydrocarbon group portion of the fatty acid of the monoglyceride preferably has 8 to 22 carbon atoms. When the carbon number of the hydrocarbon group portion of the fatty acid of the monoglyceride is less than 8, the adsorptivity to the metal surface is weak and the resulting friction coefficient reducing effect is small. Moreover, when carbon number of the hydrocarbon group part of the fatty acid of a monoglyceride exceeds 22, the solubility with respect to a lubricating base oil will be scarce, and it will lack practicality. Specific examples of the hydrocarbon group having 8 to 22 carbon atoms include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, Alkyl groups such as octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group (these alkyl groups may be linear or branched), octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group , Alkenyl groups such as tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, nonadecenyl group, icocenyl group, henicocenyl group, dococenyl group (these alkenyl groups may be linear or branched, The position of the double bond is also arbitrary, and the cis And it may be any of trans.) And the like.

  Further, the hydroxyl value of monoglyceride depends on the number of carbon atoms of the hydrocarbon group of the fatty acid, but when the number of carbon atoms is in the range of 8 to 22 as described above, it is based on the hydroxyl value measurement method according to JIS K0070. It is suitable that it is 150-350 mgKOH / g. When the hydroxyl value is lower than 150 mgKOH / g, the solubility is high, but the adsorptivity to metal is low, and the effect of reducing the friction coefficient is small. When the hydroxyl value is higher than 350 mgKOH / g, the adsorptivity is strong, but the solubility is poor and the practicality cannot be endured. The hydroxyl value is preferably 200 to 350 mgKOH / g, and more preferably 220 to 330 mgKOH / g.

  Furthermore, the content of monoglyceride is in the range of 0.3 to 2.0 mass%, preferably 0.4 to 1.7 mass%, more preferably 0.5 to 1.5 mass%, based on the total amount of the composition. It can be illustrated.

<Fatty acid ester or derivative thereof>
As described above, the lubricating oil composition according to the present embodiment contains a specific fatty acid ester or a fatty acid ester derivative obtained by adding polyoxyethylene to the fatty acid ester (hereinafter referred to as “fatty acid ester or the like”). Moreover, as a fatty acid ester etc. in this form, the thing whose HLB value calculated by either of the following formula shows 1.0-4.0 is used. This method for calculating the HLB value is a method called the Griffin method devised by Griffin of Atlas, USA. For details of the Griffin method, for example, “Introduction to Surfactant” (Sanyo Kasei Kogyo Co., Ltd., Takehiko Fujimoto, June 2007, 1st edition, p. 142) can be referred to. Here, the value of HLB (Hydrophile-Lipophile Balance) indicates the ratio of hydrophilic group to hydrophobic group, and generally includes the Griffin method, the Oda method, the Davis method, etc., but nonionics such as polyethylene glycol type and polyhydric alcohol The surfactant HLB is calculated by the Griffin method “Introduction to Surfactant” (Sanyo Kasei Kogyo Co., Ltd., Takehiko Fujimoto, June 2007, 1st edition, p. 142).
Nonionic surfactant HLB = (molecular weight of hydrophilic group portion / molecular weight of surfactant) × 20

Moreover, HLB of the fatty acid ester of polyhydric alcohol which is a kind of nonionic surfactant can also be calculated by the following formula.
HLB value of fatty acid ester, etc. = 20 × (1-S / A)
S: Saponification value of the fatty acid ester [mgKOH / g]
A: Acid value of the fatty acid ester [mgKOH / g]

  Here, as described above, the lubricating oil composition according to the present embodiment contains monoglyceride having an excellent friction reducing effect as an ashless friction modifier, and this monoglyceride is adsorbable on a metal surface. Is strong. Strong adsorption on the metal surface leads to the effect of reducing the coefficient of friction by preventing contact between metals, while forming an adsorption film at the interface between water and oil (base oil). It is expected that the tendency will be easy. Therefore, the lubricating oil composition containing monoglyceride has strong demulsibility and water separation properties, and when used for an internal combustion engine, when the condensed water of water vapor generated by the combustion of fuel is mixed into the oil, It becomes easy to deposit water on the metal surface. Since the deposited water also contains oxidized combustion residues, there is a concern that rust and corrosion may be caused on the metal surfaces of engine parts.

  In order to improve the demulsibility and water separability in the lubricating oil composition, it is necessary to change the balance between hydrophilicity and hydrophobicity, so it is necessary to add other surfactants. At this time, care must be taken so that the surfactant to be added does not adversely affect the wear resistance and friction reduction effect (fuel economy) of the lubricating oil composition.

  Therefore, in this embodiment, the lubricating oil composition containing monoglyceride contains the above-described fatty acid ester having an HLB value of 1.0 to 4.0, so that the friction of monoglyceride which is an ashless friction modifier is included. Without impeding the reduction effect and without reducing the wear resistance of the lubricating oil composition, it is possible to have a water embedding force (Emulsion Retention) suitable for the lubricating oil composition. And water separation properties can be improved, and further, rust prevention and corrosion resistance can be improved.

  The fatty acid ester used in the present embodiment having the effects as described above is a fatty acid ester in which a fatty acid is ester-bonded to at least one hydroxyl group of a compound having a hydroxyl group such as alcohol or saccharide, and the HLB value is 1 Although it will not restrict | limit especially if it exists in the range of 0.0-4.0, The following specific examples are mentioned as a compound and fatty acid which have a hydroxyl group.

  Examples of the compound having a hydroxyl group include methanol, ethanol, propanol, isopropyl alcohol, butanol, hexanol, octanol, 2-ethyl-hexyl alcohol, ethylene glycol, propylene glycol, trimethylolpropane, pentaerythritol, sorbitan, sorbitol, polyethylene glycol. And polypropylene glycol.

  Examples of fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, 12-hydroxystearic acid, erucic acid, linoleic acid, α-linolenic acid, and the like. .

  Among the above-mentioned various fatty acid esters, the fatty acid ester is a sorbitan fatty acid ester from the viewpoint that the HLB value is in the range of 1.0 to 4.0 and the above-described water entrapment force is further increased. Preferably there is. Here, the sorbitan fatty acid ester is relatively easily dissolved in the lubricating oil, easily available, and has a moderate hydroxyl group in the molecule, and therefore has a strong adsorptivity to the metal surface. Therefore, by adding the sorbitan fatty acid ester to the lubricating oil composition, not only the sorbitan fatty acid ester is dissolved well in the lubricating oil, but also a friction reducing effect and an oily effect are easily obtained, The monoglyceride contained in the lubricating oil composition of the present embodiment does not adversely affect the wear resistance and the friction coefficient reducing effect (fuel economy).

  From the same viewpoint, a fatty acid triester in which the compound having a hydroxyl group is sorbitan is preferable. Furthermore, as the fatty acid ester according to this embodiment, a sorbitan fatty acid triester that satisfies both of the above conditions is particularly preferable.

  The HLB value of the fatty acid ester or the like used in the present embodiment needs to be 1.0 to 4.0 as described above, but from the viewpoint of further strengthening the power to embrace water (Emulsion Retention). The HLB value is preferably 1.0 to 3.8, more preferably 1.0 to 3.5.

  Content of fatty acid ester etc. is 0.7 mass% or more on the basis of the whole quantity of lubricating oil composition. If the content of the fatty acid ester or the like is less than 0.7% by mass, the force for embedding water (Emulsion Retention) is insufficient, and the water present in the lubricating oil composition may be separated. From the standpoint of further strengthening the power of embracing water, the content of fatty acid ester or the like is preferably 0.8% by mass or more, and more preferably 0.9% by mass or more. On the other hand, if the content of the fatty acid ester or the like is too large, the adsorption of the antiwear agent is hindered and the wear resistance may be lowered. Therefore, the content of the fatty acid ester or the like may be 2.0% by mass or less. preferable.

<Other optional components>
In order to further improve the performance of the lubricating oil composition in addition to the components described above, various additives can be appropriately used as necessary. These include pour point depressants, antioxidants, metal deactivators, antiwear agents, antifoaming agents, viscosity index improvers, detergent dispersants, rust inhibitors, and other known lubrications. Mention may be made of oil additives.

(Pour point depressant)
A pour point depressant may be added to the lubricating oil composition according to this embodiment in order to improve low temperature fluidity. The pour point depressant is not particularly limited. For example, the polymethacrylate polymer also has a function as a pour point depressant. The addition amount of the pour point depressant can be used in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the base oil.

(Antioxidant)
As the antioxidant used in this embodiment, those used for lubricating oil are practically preferable, and examples thereof include amine-based antioxidants, sulfur-based antioxidants, phenol-based antioxidants, and phosphorus-based antioxidants. be able to. These antioxidants can be used alone or in combination within a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the base oil.

  Examples of the amine antioxidant include p, p′-dioctyl-diphenylamine (Seiko Chemical Co., Ltd .: Nonflex OD-3), p, p′-di-α-methylbenzyl-diphenylamine, and Np-butylphenyl. Dialkyl-diphenylamines such as -Np'-octylphenylamine, monoalkyldiphenylamines such as mono-t-butyldiphenylamine and monooctyldiphenylamine, di (2,4-diethylphenyl) amine, di (2-ethyl- Bis (dialkylphenyl) amines such as 4-nonylphenyl) amine, alkylphenyl-1-naphthylamines such as octylphenyl-1-naphthylamine, Nt-dodecylphenyl-1-naphthylamine, 1-naphthylamine, phenyl-1 -Naphthylamine, phenyl-2-na Aryl-naphthylamines such as tilamine, N-hexylphenyl-2-naphthylamine, N-octylphenyl-2-naphthylamine, N, N′-diisopropyl-p-phenylenediamine, N, N′-diphenyl-p-phenylenediamine, etc. Phenylenediamines, phenothiazines (manufactured by Hodogaya Chemical Co., Ltd .: Phenothiazine), and phenothiazines such as 3,7-dioctylphenothiazine.

  Examples of sulfur-based antioxidants include dialkyl sulfides such as didodecyl sulfide and dioctadecyl sulfide, didodecyl thiodipropionate, dioctadecyl thiodipropionate, dimyristyl thiodipropionate, and dodecyl octadecyl thiodipropionate. Examples include thiodipropionic acid esters and 2-mercaptobenzimidazole.

  Examples of phenolic antioxidants include 2-t-butylphenol, 2-t-butyl-4-methylphenol, 2-t-butyl-5-methylphenol, 2,4-di-t-butylphenol, 2,4- Dimethyl-6-t-butylphenol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,5-di-t-butylhydroquinone (manufactured by Kawaguchi Chemical Co., Ltd .: Antage DBH), 2,6-di-t-butylphenol such as 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol 2,6-di-tert-butyl-4-, such as -4-alkylphenols, 2,6-di-tert-butyl-4-methoxyphenol, 2,6-di-tert-butyl-4-ethoxyphenol There is a Turkey alkoxy phenols.

  3,5-di-t-butyl-4-hydroxybenzyl mercapto-octyl acetate, n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (manufactured by Yoshitomi Pharmaceutical Co., Ltd.) Yoshinox SS), n-dodecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2'-ethylhexyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Alkyl-3- () such as propionate, benzenepropanoic acid 3,5-bis (1,1-dimethyl-ethyl) -4-hydroxy-C7-C9 side chain alkyl ester (manufactured by Ciba Specialty Chemicals: Irganox L135) 3,5-di-t-butyl-4-hydroxyphenyl) propionates, 2,6-di-t-butyl-α- Methylamino-p-cresol, 2,2′-methylenebis (4-methyl-6-t-butylphenol) (manufactured by Kawaguchi Chemical Co .: Antage W-400), 2,2′-methylenebis (4-ethyl-6-t) -Butylphenol) (Kawaguchi Chemical Co., Ltd .: Antage W-500) and the like.

  Further, 4,4′-butylidenebis (3-methyl-6-tert-butylphenol) (manufactured by Kawaguchi Chemical Co., Ltd .: Antage W-300), 4,4′-methylenebis (2,6-di-tert-butylphenol) (shell) -Japan company make: Ionox220AH), 4,4'-bis (2,6-di-t-butylphenol), 2, 2- (di-p-hydroxyphenyl) propane (shell Japan company make: bisphenol A), 2,2-bis (3,5-di-t-butyl-4-hydroxyphenyl) propane, 4,4′-cyclohexylidenebis (2,6-t-butylphenol), hexamethylene glycol bis [3- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionate] (manufactured by Ciba Specialty Chemicals: Irganox L109), tri Tylene glycol bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (Yoshitomi Pharmaceutical Co., Ltd .: Tominox 917), 2,2′-thio- [diethyl-3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate] (manufactured by Ciba Specialty Chemicals: Irganox L115), 3,9-bis {1,1-dimethyl-2- [3- (3-t-butyl -4-hydroxy-5-methylphenyl) propionyloxy] ethyl} 2,4,8,10-tetraoxaspiro [5,5] undecane (Sumitomo Chemical: Sumilizer GA80), 4,4'-thiobis (3-methyl -6-tert-butylphenol) (manufactured by Kawaguchi Chemical Co .: Antage RC), 2,2'-thiobis (4,6-di-tert-butyl-resorcin), etc. There is a bisphenol.

  Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (manufactured by Ciba Specialty Chemicals: Irganox L101), 1,1,3-tris (2-methyl) -4-hydroxy-5-t-butylphenyl) butane (Yoshitomi Pharmaceutical Co., Ltd .: Yoshinox 930), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4 -Hydroxybenzyl) benzene (manufactured by Shell Japan: Ionox 330), bis- [3,3′-bis- (4′-hydroxy-3′-t-butylphenyl) butyric acid] glycol ester, 2- (3 ', 5'-di-tert-butyl-4-hydroxyphenyl) methyl-4- (2 ", 4" -di-tert-butyl-3 "-hydroxyphenyl Polyphenols such as methyl-6-tert-butylphenol, 2,6-bis (2′-hydroxy-3′-tert-butyl-5′-methyl-benzyl) -4-methylphenol, pt-butylphenol and formaldehyde And a phenol aldehyde condensate such as a condensate of pt-butylphenol and acetaldehyde.

  Examples of phosphorus antioxidants include triaryl phosphites such as triphenyl phosphite and tricresyl phosphite, trialkyl phosphites such as trioctadecyl phosphite and tridecyl phosphite, and tridodecyl trithiophosphite. It is done.

  Regarding the sulfur-based and phosphorus-based antioxidants, the blending amount must be limited in consideration of the influence on the exhaust gas control system of the internal combustion engine. The phosphorus content in the entire lubricating oil is 0.10% by mass or less, and the sulfur content is preferably 0.6% by mass or less, more preferably the phosphorus content is 0.08% by mass or less, and the sulfur content is 0.5% by mass or less.

(Metal deactivator)
Examples of the metal deactivator that can be used in combination with the composition according to this embodiment include benzotriazole, 4-methyl-benzotriazole, 4-alkyl-benzotriazoles such as 4-ethyl-benzotriazole, 5-methyl-benzotriazole, 5-alkyl-benzotriazoles such as 5-ethyl-benzotriazole, 1-alkyl-benzotriazoles such as 1-dioctylaminomethyl-2,3-benzotriazole, 1-dioctylaminomethyl-2,3-toltriazole and the like Benzotriazole derivatives such as 1-alkyl-tolutriazoles, 2- (octyldithio) -benzimidazole, 2- (decyldithio) -benzimidazole, 2- (dodecyldithio) -benzimidazole, 2- ( Alkyldithio) -be Benzimidazole derivatives such as 2- (alkyldithio) -toluimidazoles such as zoimidazoles, 2- (octyldithio) -toluimidazole, 2- (decyldithio) -toluimidazole, 2- (dodecyldithio) -toluimidazole, etc. is there.

  Further, indazole derivatives such as tolindazoles such as indazole, 4-alkyl-indazole, 5-alkyl-indazole, benzothiazole, 2-mercaptobenzothiazole derivative (manufactured by Chiyoda Chemical Co., Ltd .: Thiolite B-3100), 2- (hexyl) 2- (alkyldithio) benzothiazoles such as dithio) benzothiazole and 2- (octyldithio) benzothiazole, 2- (alkyldithio) such as 2- (hexyldithio) tolthiazole and 2- (octyldithio) tolthiazole Tolthiazoles, 2- (N, N-diethyldithiocarbamyl) benzothiazole, 2- (N, N-dibutyldithiocarbamyl) -benzothiazole, 2- (N, N-dihexyldithiocarbamyl) -benzothiazole 2- (N, N-dialkyl such as Thiocarbamyl) benzothiazoles, 2- (N, N-diethyldithiocarbamyl) tolthiazole, 2- (N, N-dibutyldithiocarbamyl) tolthiazole, 2- (N, N-dihexyldithiocarbamyl) torthiazole Benzothiazole derivatives such as 2- (N, N-dialkyldithiocarbamyl) -torzothiazoles.

  Furthermore, 2- (alkyldithio) -benzoxazoles such as 2- (octyldithio) benzoxazole, 2- (decyldithio) benzoxazole, 2- (dodecyldithio) benzoxazole, 2- (octyldithio) toluoxazole, 2 Benzoxazole derivatives such as 2- (alkyldithio) toluxazoles such as-(decyldithio) toluxazole and 2- (dodecyldithio) toluxazole, 2,5-bis (heptyldithio) -1,3,4-thiadiazole, 2 , 5-bis (nonyldithio) -1,3,4-thiadiazole, 2,5-bis (dodecyldithio) -1,3,4-thiadiazole, 2,5-bis (octadecyldithio) -1,3,4 2,5-bis (alkyldithio) -1,3,4-thiadiazo such as thiadiazole 2,5-bis (N, N-diethyldithiocarbamyl) -1,3,4-thiadiazole, 2,5-bis (N, N-dibutyldithiocarbamyl) -1,3,4-thiadiazole 2,5-bis (N, N-dialkyldithiocarbamyl) -1,3,4-thiadiazoles such as 2,5-bis (N, N-dioctyldithiocarbamyl) -1,3,4-thiadiazole 2-N, N-dibutyldithiocarbamyl-5-mercapto-1,3,4-thiadiazole, 2-N, N-dioctyldithiocarbamyl-5-mercapto-1,3,4-thiadiazole Thiadiazole derivatives such as N, N-dialkyldithiocarbamyl-5-mercapto-1,3,4-thiadiazoles, 1-amines such as 1-di-octylaminomethyl-2,4-triazole Triazole derivatives of Kill 2,4 triazoles such like. These metal deactivators can be used alone or in combination within a range of 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the base oil.

(Antiwear agent)
In order to impart wear resistance to the lubricating oil composition according to the present embodiment, a phosphorus compound can be added as an antiwear agent. Examples of the phosphorus compound suitable for this embodiment include zinc dithiophosphate and zinc phosphate. These phosphorus compounds are 0.01 to 2% by mass with respect to 100 parts by mass of the base oil, and the phosphorus content is preferably 0.05 to 0.10% by mass, more preferably 0.00%, based on the entire lubricating oil. It can be used alone or in combination in the range of 05-0.08 mass%. If the phosphorus content exceeds 0.10% by mass based on the entire lubricating oil, it will adversely affect the catalyst of the exhaust gas control system, etc. If the phosphorus content is less than 0.05% by mass, the wear resistance as engine oil Cannot be maintained.

  Examples of the zinc dithiophosphate generally include zinc dialkyldithiophosphate, zinc diaryldithiophosphate, zinc arylalkyldithiophosphate, and the like. As the hydrocarbon group, for example, the alkyl group includes a primary or secondary alkyl group having 3 to 12 carbon atoms. As the aryl group, a phenyl group or a phenyl group is substituted with an alkyl group having 1 to 18 carbon atoms. And alkylaryl groups.

  Among these zinc dithiophosphates, zinc dialkyldithiophosphates having a secondary alkyl group are preferable, and the number of carbon atoms is 3 to 12, preferably 3 to 8, and more preferably 3 to 6.

(Defoamer)
In order to impart antifoaming properties to the lubricating oil composition according to this embodiment, an antifoaming agent may be added. Examples of the antifoaming agent suitable for this embodiment include organosilicates such as dimethylpolysiloxane, diethyl silicate and fluorosilicone, and non-silicone antifoaming agents such as polyalkyl acrylate. The addition amount can be used individually or in combination within a range of 0.0001 to 0.1 parts by mass with respect to 100 parts by mass of the base oil.

≪Lubricating oil composition-properties≫
The viscosity of the lubricating oil composition according to this embodiment is not particularly limited, but the viscosity index may be 100 or more, preferably 110 or more, more preferably 120 or more, and the upper limit of the viscosity index is 300 or less. Also good. The kinematic viscosity at 100 ° C. of the lubricating oil composition is 5.6 to 15 mm ² / s, preferably 5.6 to 12.5 mm ² / s, more preferably 5.6 to 11.0 mm ² / s. There may be.

≪Lubricating oil composition-application≫
The lubricating oil composition according to this embodiment is used as a lubricating oil composition for internal combustion engines. The lubricating oil composition according to the present embodiment has an H / C ratio of 1.75 to 4 (preferably 1.80 to 4, more preferably 1.93 to 4, more preferably 2.67 to 4). It can be used in an internal combustion engine using fuel. The H / C (carbon hydrogen ratio) of commercial premium gasoline and regular gasoline are 1.763 and 1.875, respectively. If 3% of this premium gasoline and regular gasoline are replaced with (bio) ethanol or the like, the H / C will be approximately 1.80 and 1.91, respectively. The H / C of the commercially available No. 2 diesel oil equivalent “BASE” is 1.91, and the diesel diesel oil JIS No. 2 has an H / C of 1.927, and 5% of these are stearins as representative biofuels for diesel engines. When converted to methyl acid, H / C is about 1.93. Examples of the fuel having an H / C ratio of 1.75 to 4 include commercially available premium gasoline, regular gasoline, premium gasoline in which 3% of these are replaced with (bio) ethanol, and regular gasoline (H / C = 1.80 and 1.91), 5% of diesel diesel oil JIS 2 is replaced with methyl stearate as a representative biofuel for diesel engine blending (H / C = 1.93), propane (H / C = 2.6), natural gas (H / C = 4 when methane is the main component). Further, the lubricating oil composition according to the present embodiment can be used in an internal combustion engine of a vehicle equipped with an idling stop device. Furthermore, the lubricating oil composition according to the present embodiment is a biogasoline fuel or biofuel (for example, fatty acid methyl ester, plant and tallow) obtained by adding biofuel (for example, bioethanol, ethyl tert-butyl ether, or cellulosic ethanol) to gasoline. Hydrotreating oil obtained by decomposing and refining raw oils and fats using petroleum refining hydrotreating technology, or biomass pyrolysis gas using catalytic reaction from carbon monoxide and hydrogen by FT (Fischer Tropsch) method It is suitably used in an internal combustion engine using a biodiesel fuel (biodiesel fuel) obtained by adding a synthetic oil produced by synthesizing liquid hydrocarbons to light oil. In particular, the lubricating oil composition according to the present embodiment is suitably used for an internal combustion engine using biogasoline fuel containing biofuel in an amount of more than 3% by volume, preferably 5% by volume or more, more preferably 10% by volume or more. The In particular, the lubricating oil composition according to the present embodiment uses biodiesel fuel (biolight oil fuel) in which biofuel is blended with light oil in an amount of more than 5% by mass, preferably 7% by mass or more, more preferably 10% by mass or more. It is preferably used for an internal combustion engine.

  Below, it has the excellent wear resistance and fuel saving performance of the present invention, and also has the ability to prevent the corrosion and rust of the internal combustion engine by dispersing condensed water due to water vapor generated by fuel combustion etc. in the oil. The lubricating oil composition for an internal combustion engine will be specifically described with reference to examples and comparative examples, but the present invention is not limited thereto.

<< 1. Composition material >>
In preparing Examples and Comparative Examples, the following composition materials were prepared.

<Base oil>
Base oils 1 to 4 used in Examples and Comparative Examples have the properties shown in Table 1. Here, the kinematic viscosity at 40 ° C. and the kinematic viscosity at 100 ° C. are values obtained by JIS K 2283 “Crude oil and petroleum products—Kinematic viscosity test method and viscosity index calculation method”. The viscosity index is a value obtained in accordance with JIS K 2283 “Crude oil and petroleum products—Kinematic viscosity test method and viscosity index calculation method”. Furthermore, pour point (PP) is JIS K 2269, flash point is JIS K 2265-4 (COC: Cleveland open method), sulfur content is JIS K 2541 (radiation excitation type method),% C _A , % for _{C N} and% _{C P} those values obtained in conformity with ASTM D3238, was used respectively. The base oil-4 is a base oil produced from GTL (gas-liquid) wax synthesized by the Fischer-Tropsch method.

<Additives>
[Additive A: Monoglyceride]
In the examples, the properties of monoglycerides formulated as additives are shown below. As the monoglyceride of this example, the following properties were used.
・ White paste glycerin monooleate (partial ester of glycerin and oleic acid which has 18 carbon atoms) at 25 ° C
Melting point: 41 ° C
Flash point (COC) 220 ° C
・ Acid value less than 1.0 mgKOH / g ・ Hydroxyl value 222 mgKOH / g
[Additive B: Viscosity index improver]
In Examples and Comparative Examples, viscosity index improvers blended as additives are shown below. For the measurement of molecular weight, Shodex GPC-101 manufactured by Showa Denko KK and high performance liquid chromatography was used. The measurement conditions were a temperature of 40 ° C., a detector with a refractive index detector (RI), and a carrier flow rate of THF. −1.0 ml / min (Ref 0.3 ml / min), sample injection amount 100 μl, column {KF-G (Shodex) × 1, KF-805L (Shodex × 2)}, peak molecular weight 2,600 Using the range corresponding to ˜690,000, the average molecular weight (polystyrene equivalent value) was analyzed (calculated).
Weight average molecular weight (Mw): 283,000
Number average molecular weight (Mn): 269,000
Non-dispersion type polymethacrylate (PMA) -based polymer with Mw / Mn = 1.05 [Additive C: Package additive for ILSAC GF-5]
Additive C is an additive package for internal combustion engine oil, and contains an antiwear agent, a dispersant, a metallic detergent, an antioxidant, a metal deactivator, and the like. In the product catalog of Oronite, it is described that the performance suitable for API-SN and ILSAC GF-5 standards can be obtained when 8.9-10.55% by mass of the additive is added to the lubricating oil. . Therefore, in the Examples, the amount of the additive C is 9.05% by mass and the amount suitable for the ILSAC GF-5 standard is used. However, the amount of additive C is not particularly limited.
[Additive D: Antifoam solution]
This is an antifoaming agent solution in which 3% by mass of a dimethylpolysiloxane type silicone oil is dissolved in light oil.
[Additive E: Fatty acid ester, etc.]
In Examples and Comparative Examples, fatty acid esters or derivatives thereof (surfactants) blended as additives, their HLB values, and product names are shown below. In the following, the numerical values in parentheses indicate HLB values.
・ Sorbitan trioleate (1.8): Rheodor SP-O30V (manufactured by Kao Corporation)
Sorbitan tristearate (2.1): Rheodor SP-S30 (manufactured by Kao Corporation)
Sorbitan monooleate (4.3): Rheodor SP-O10V (manufactured by Kao Corporation)
Sorbitan monolaurate (8.6): Rheodor SP-L10 (manufactured by Kao Corporation)
Polyoxyethylene (POE) sorbitan monooleate (10.0): Rheodor TW-O106V (manufactured by Kao Corporation)
Polyoxyethylene (POE) sorbitan monolaurate (13.3): Rheodor TW-L106 (manufactured by Kao Corporation)

≪2. Preparation of lubricating oil composition >>
Using the above-mentioned composition materials, lubricating oil compositions for internal combustion engines of Examples 1 to 5 and Comparative Examples 1 to 11 were prepared with the compositions shown in Table 2.

≪3. Exam >>
For the lubricating oil compositions of Examples 1 to 5 and Comparative Examples 1 to 11, various tests shown below were performed to see the performance.
(1) Demulsibility test In order to evaluate the emulsification stability (performance of embedding water) of a lubricating oil, the following emulsification test based on ASTM D7563 was performed.
Using a commercially available blender capable of stirring at high speed, for example, WARING BLENDER 7011H (currently 7011S) using a stainless steel container manufactured by MFI Co., Ltd. An evaluation test was conducted using water. The test procedure is as follows.
At room temperature (20 ° C. ± 5 ° C.), 185 ml of test oil to be evaluated with a 200 ml graduated cylinder was measured and put into a blender 7011H. Next, 15 ml of prototype E85 fuel was measured with a 100 ml graduated cylinder, and this was put into a blender 7011H. Finally, 15 ml of distilled water was measured with a 100 ml graduated cylinder, and this was put into 7011H. Immediately after that, the container was covered and stirred for 60 seconds at a rotational speed of 15000 rpm. Immediately after the stirring, 100 ml of the mixed solution was put into a 100 ml graduated cylinder with a sliding glass stopper with a lid, and left in a constant temperature bath at a predetermined temperature (-5 to 0 ° C. or 20 to 25 ° C.) for 24 hours. After stirring, let stand in a thermostatic bath for 24 hours, measure the amount of oil-emulsion-water with a graduated cylinder scale, water separation is seen as "water separation", water separation is not seen The results are shown in Table 2 as “no water separation”.
As the prototype E85 fuel, 150 ml of commercially available JIS No. 1 automobile gasoline and 850 ml of special grade ethanol from Wako Pure Chemical Industries were measured with a graduated cylinder and mixed so as to be uniform at room temperature.
The mixing required for the test was completed in a short period of time within a specified time, and was kept in a cool and dark place indoors in a container that could be tightly sealed so that light components would not evaporate.
(2) Shell-type 4-ball wear test The shell-type 4-ball test was performed in accordance with ASTM D4172 under the conditions of a rotation speed of 1800 rpm, an oil temperature of 50 ° C., a load of 40 kgf, and a time of 30 minutes. After the test, the test piece was taken out, the wear scar diameter was measured, and the result was shown.
(3) Friction coefficient measurement test In order to see the friction characteristics, the friction coefficient was measured and evaluated using a CAMERON-PLINT / TE77 tester used in ASTM-G-133 (American Society for Testing and Materials). The upper test piece is made of SK-3 and has a cylindrical shape with a diameter of 6 mm and a length of 16 mm. The lower test piece is a plate made of SK-3, and the test temperature is 80.degree. A minute test was performed and the average value of the coefficient of friction measured during the last stable minute was noted. A smaller friction coefficient indicates better friction reduction.

<< 4. Results and discussion >>
Table 2 shows the results of the above tests for Examples 1 to 5 and Comparative Examples 1 to 11.

  Comparative Example 1 was an engine oil containing no glycerin monooleate, and no water separation was observed in the demulsibility test. However, since Comparative Example 1 does not include glycerin monooleate as a result of the friction coefficient measurement test, the wear scar diameter is as high as 0.42 mm and the friction coefficient is as high as 0.112. I found out I couldn't get it.

  In Comparative Example 2, glycerin monooleate is added, so that the wear scar diameter is 0.35 mm and the friction coefficient is less than 0.10, which is smaller than the case where no glycerin monooleate is included, and the friction coefficient is reduced. The fuel-saving effect by was obtained. However, in Comparative Example 2, it was found that water was separated in the demulsibility test at 25 ° C. due to the surfactant activity of glycerin monooleate.

  In Comparative Examples 3 to 5, a fatty acid ester or the like (surfactant) having a low HLB of 4.0 or less was used, but in the demulsibility test at 25 ° C., the concentration was 0.5% by mass or less. Was found to separate. From this result, even when a fatty acid ester having an HLB of 4.0 or less is added, if the content is less than 0.7% by mass, the effect of improving the demulsibility and water separability is low and sufficient water is sufficient. It was suggested that the force to embrace (emulsion stability) could not be obtained. In Comparative Examples 3 to 5, as in Comparative Example 2, the wear scar diameter is 0.37 mm or less and the friction coefficient is less than 0.10, which is smaller than when no glycerin monooleate is included, and the friction coefficient is reduced. The fuel-saving effect of was obtained.

  In Comparative Examples 6 to 9, the fatty acid ester or the like (surfactant) having an HLB of 4.3 or 8.6 was used, but in this case, not only when the concentration was as low as 0.5% by mass, It was found that even when the concentration was increased to 0.9% by mass, water was embraced but was weak and the water separated. From this result, even when fatty acid esters with HLB exceeding 4.0 are added, the effect of improving the anti-emulsification property and water separation property is low, and sufficient water embedding power (emulsification stability) cannot be obtained. Was suggested. In Comparative Examples 6 to 9, as in Comparative Example 2, the wear scar diameter is 0.36 mm or less and the friction coefficient is less than 0.10, which is smaller than when no glycerin monooleate is included, and the friction coefficient is reduced. The fuel-saving effect of was obtained.

  In Comparative Examples 10 and 11, a fatty acid ester or the like (surfactant) having an HLB of 10.0 or more was used, but in this case, water was separated in the demulsibility test at 0 ° C. and 25 ° C. It was impossible to embed water in the lubricating oil. In Comparative Examples 10 and 11, as in Comparative Example 2, the wear scar diameter is 0.38 mm or less, and the friction coefficient is less than 0.10, which is smaller than when no glycerin monooleate is included, and the friction coefficient is reduced. The fuel-saving effect of was obtained.

  In Examples 1, 2, 3, and 4, those belonging to Group 3 of the API base oil classification with a low sulfur content and a low degree of unsaturation were used. In this case, if 0.7% by mass or more of a fatty acid ester having an HLB in the range of 1.0 to 4.0 is added, the water separability due to the strong surfactant effect of glycerin monooleate is canceled, It was found that the emulsification-retention can be improved. Further, even when the fatty acid ester or the like is added, these properties and effects are maintained without impairing the wear resistance and the friction coefficient reducing effect.

  In Example 5, GTL (Gas Liquid Liquid) base oil synthesized by the Fischer-Tropsch method among API Group 3 base oils and API Group 2 base oils were used. Even when these base oils are used, if 0.7% by mass or more of a fatty acid ester having an HLB in the range of 1.0 to 4.0 is added, the wear resistance and the friction coefficient reducing effect are maintained. It has been found that the ability to release water separation and improve the ability to embrace water (Emulsion-Retention) can be improved.

The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment. That is, it is understood that other forms or various modifications that can be conceived by those skilled in the art within the scope of the invention described in the claims belong to the technical scope of the present invention.

Claims (3)

(A) Kinematic viscosity at 100 ° C. is 3.0 to 12.0 mm ² / s, and selected from the group consisting of base oils classified into groups 2, 3 and 4 in the API (American Petroleum Institute) base oil category At least one base oil, and
(B) A monoglyceride having a hydrocarbon group having 8 to 22 carbon atoms and a hydroxyl value of 150 to 350 mgKOH / g is 0.3 to 2.0% by mass based on the total amount of the composition,
(C) A fatty acid ester having an HLB value of 1.0 to 4.0, or a fatty acid ester derivative obtained by adding polyoxyethylene to the fatty acid ester, 0.7% by mass or more based on the total amount of the composition,
Contain,
It is used in an internal combustion engine using a fuel having an H / C ratio of 1.75 to 4, an internal combustion engine of a vehicle with an idling stop device, or an internal combustion engine using a fuel blended with biofuel. A lubricating oil composition for an internal combustion engine. The lubricating oil composition for an internal combustion engine according to claim 1, wherein the fatty acid ester is a sorbitan fatty acid ester. The lubricating oil composition for an internal combustion engine according to claim 1 or 2 , wherein the fatty acid ester is a fatty acid triester.