JP2001139978A - Lubricating oil composition for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricating oil composition for an internal combustion engine which is excellent in friction loss reduction in the internal combustion engine of an automobile and is especially suitable for a diesel engine equipped with an exhaust gas recirculator(EGR). SOLUTION: This lubricating oil composition for an internal combustion engine, especially for a diesel engine equipped with an EGR features formulating 0.01-40 wt.%, based on the total weight of the composition, of at least one kind selected from the group consisting of an alkylene oxide adduct to a polyhydric alcohol-partially esterified fatty acid and a fatty acid-partially esterified polyethylene glycol in a base oil composed of a mineral oil and/or a synthetic lubricant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition for an internal combustion engine, and more particularly, to a lubricating oil composition excellent in friction loss reduction for an internal combustion engine of an automobile, particularly an exhaust gas recirculation device (hereinafter abbreviated as EGR). The present invention relates to a fuel-saving lubricating oil composition for an internal combustion engine suitable for use in a diesel engine equipped with the above.

[0002]

2. Description of the Related Art Generally, an engine having a sliding portion is provided.
Lubricating oil is used in internal combustion engines, automatic transmissions, shock absorbers, drive system devices such as power steering, gears, and the like in order to facilitate their operations. In particular, lubricating oil for internal combustion engines mainly lubricates various sliding parts such as piston rings and cylinder liners, bearings for crankshafts and connecting rods, and valve trains including cams and valve lifters, as well as cooling and combustion generation in the engine. It acts to clean and disperse things and prevent rust and corrosion. As described above, lubricating oils for internal combustion engines are required to have various performances, and in recent years, advanced performances have been required in accordance with higher performance, higher output, and more severe operating conditions of internal combustion engines. I have.
Therefore, various additives for satisfying such required performance, for example, an antiwear agent, a metal detergent, an ashless dispersant, an antioxidant, and the like are blended in the lubricating oil for an internal combustion engine. As a basic function of a lubricating oil for an internal combustion engine, it is important to make the engine operate smoothly, particularly under all conditions, to prevent wear and seizure. Most of the engine lubrication part is in a fluid lubrication state, but it tends to be in a boundary lubrication state at the valve operating system or at the top and bottom dead center of the piston. It is provided by addition.

[0003] In an internal combustion engine, since energy loss is large in a friction portion in which lubricating oil is involved, measures for reducing friction loss and reducing fuel consumption, for example, are disclosed in Japanese Patent Publication No. 3-23.
As shown in Japanese Patent Application Publication No. 595, a lubricating oil in which various additives such as a friction reducing agent are combined is used. The internal combustion engine of an automobile is operated over a wide range of oil temperatures, rotation speeds, and loads. Therefore, in order to further improve fuel efficiency, a lubricating oil for an internal combustion engine has excellent friction characteristics under a wide range of use conditions. There is a need.

Heretofore, in order to lower the friction coefficient of lubricating oil, an organic molybdenum compound has been added, and a combination of an organic molybdenum compound and a metallic detergent (for example, Japanese Patent Publication No. 6-62).
983), a combination of an organic molybdenum compound and a sulfur-based compound (for example, Japanese Patent Publication No. 5-83599),
Alternatively, a combination of an organic molybdenum compound, zinc dithiophosphate and a sulfur compound (for example, JP-A-8-73878) has been used. Examples of the friction reducing agent other than the organic molybdenum compound include a combination of a glycerol partial ester of a fatty acid and an organic copper compound (for example, Japanese Patent Publication No. 3-77837), a pentaerythritol ester and a succinimide or dithiophosphoric acid. Combination with zinc (for example, JP-A-55-80494,
JP-A-55-82195) has been proposed. However, in a diesel engine, unlike a gasoline engine, a large amount of soot produced by incomplete combustion of light oil is mixed into engine oil. It is said that this soot in oil has a surface activity and therefore has an effect of adsorbing polar additives in oil and shaving off a film formed on a friction surface. Therefore, under such severe frictional conditions that soot is mixed in oil, the mode of action as a friction reducer is significantly different from that of a gasoline engine, and conventional friction reducers, that is, organic molybdenum compounds, amines and amides are used. , Phosphate esters and the like are said to have no sufficient effect on reducing fuel consumption of diesel engines. Therefore, in order to improve the fuel-saving performance of a diesel engine, a compounded oil of an alkali metal borate hydrate (for example, Japanese Patent Publication No. 1-48319) or a compounded oil of a partial ester of a polyhydric alcohol (JP-A-2000-2)
No. 6879) is merely proposed. In addition, since exhaust gas pollution from diesel engines, especially air pollution due to NOx and the like, is becoming more serious worldwide, new regulations are being added on NOx and the like emitted from diesel vehicles to reduce emissions. In response to these exhaust gas regulations, engine manufacturers are adopting EGR measures used in gasoline engines as a NOx reduction measure. The effects of this EGR include that the number of suits in oil further increases, the suits increase the valve train and piston / cylinder wear, and the effect of reducing the fuel consumption by the friction reducing agent is not sufficiently exhibited. Are listed. On the other hand, it is known that lowering the viscosity of a lubricating oil is also effective as a means for improving fuel efficiency, and a viscosity index improver such as polymethacrylate or ethylene-propylene copolymer is added to a low-viscosity lubricating oil. Multi-grade diesel engine oils are commonly used. However, the fuel efficiency reduction effect of a multi-grade diesel engine oil to which only these viscosity index improvers were added was insignificant and could not be said to be sufficient. For this reason, there has been a strong demand for the technical development of a lubricating oil composition for an internal combustion engine that exhibits a sufficient fuel consumption reduction effect not only in a gasoline engine but also in a diesel engine. In Japan, in particular, the average fuel economy of diesel passenger cars since 2005 was 14.9% (199
(Compared to five years), and expectations for fuel-saving technology with diesel engine oil are increasing.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil composition which is excellent in reducing the friction loss of an internal combustion engine of an automobile and is particularly suitable for a diesel engine equipped with EGR.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to overcome the problems of the prior art, and as a result, have found that a lubricating oil containing a specific amount of an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol is contained. When the composition was prepared, it was surprisingly found that a low coefficient of friction was obtained under lubricating conditions with mixed suits. The present invention has been completed based on these findings.

That is, according to the present invention, a base oil composed of mineral oil and / or synthetic lubricating oil is added in an amount of 0.1% based on the total amount of the composition.
At least one of an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol and polyethylene glycol partially esterified with a fatty acid;
There is provided a lubricating oil composition for a fuel engine, comprising a seed. Further, according to the present invention, there is provided the above lubricating oil composition for an internal combustion engine, wherein the fatty acid partial ester of the polyhydric alcohol is a sorbitan fatty acid partial ester. Further, according to the present invention, there is provided the above lubricating oil composition for an internal combustion engine, which is used for an internal combustion engine that discharges soot or a diesel engine equipped with an exhaust gas recirculation device (EGR).

The present invention provides, as described above, an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol,
Alternatively, the present invention relates to a fuel-saving lubricating oil composition for internal combustion engines containing at least one kind of polyethylene glycol partially esterified with a fatty acid. Preferred embodiments thereof include the following. (1) The lubricating oil composition for an internal combustion engine described above, wherein the fatty acid is a saturated fatty acid or an unsaturated fatty acid having 12 to 24 carbon atoms. (2) The polyhydric alcohol is at least one selected from glycerin, erythritol, arabitol, sorbitol, sorbitan, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, tripentaerythritol, ditrimethylolpropane, and a mixture thereof. A lubricating oil composition for an internal combustion engine as described above, which is a seed. (3) The lubricating oil composition for an internal combustion engine described above, wherein the alkylene oxide adduct is an ethylene oxide adduct. (4) Further, based on the total amount of the composition, 0.01 to 30% by weight of a viscosity index improver of a non-dispersible ethylene-propylene copolymer or polyisobutylene, and 0.001 in terms of nitrogen amount.
The lubricating oil composition for an internal combustion engine according to the above, comprising succinimide in an amount of up to 0.5% by weight. (5) The non-dispersible ethylene-propylene copolymer or polyisobutylene has a weight average molecular weight of 100,000 or more (GP
The lubricating oil composition for an internal combustion engine according to the above, wherein the lubricating oil composition is a polystyrene equivalent in C analysis). (6) The lubricating oil composition for an internal combustion engine described above, wherein the composition is used in a state where the amount of the suit in oil is 0.1% by weight or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. 1. Lubricating Base Oil The base oil used in the lubricating oil composition of the present invention is not particularly limited, and any base oil generally used as a lubricating base oil can be used. That is, those which correspond to these include mineral oil, synthetic lubricating oil, or a mixed oil thereof.

As the mineral oil, a solvent-refined raffinate and a lubricating oil raw material obtained by treating a lubricating oil raw material derived by distillation of crude oil under normal pressure or reduced pressure with an aromatic extraction solvent such as phenol, furfural and N-methylpyrrolidone are used. Hydrotreated oil obtained by contacting hydrogen under hydrotreating conditions in the presence of a hydrotreating catalyst, isomers obtained by contacting wax with hydrogen under isomeric conditions in the presence of a catalyst for isomerization And a lubricating oil fraction obtained by combining a solvent purification step, a hydrotreating step, an isomerization step, and the like. In any of the production methods, steps such as a dewaxing step, a hydrofinishing step, and a clay treatment step can be arbitrarily adopted by a conventional method. Specific examples of the mineral oil include light neutral oil, medium neutral oil, heavy neutral oil, bright stock, and the like. The base oil can be adjusted by appropriately mixing so as to satisfy required properties.

Examples of the synthetic lubricating oil include poly-α-olefin, α-olefin oligomer, polybutene, alkylbenzene, polyol ester, dibasic acid ester, polyoxyalkylene glycol, polyoxyalkylene glycol ether, silicone oil and the like. be able to.

These base oils can be used alone or in combination of two or more, and mineral oil and synthetic oil may be used in combination. The base oil used in the present invention is usually ^{2 to 20} mm 2/100 ° C.
s with a kinematic viscosity of 3 to 15 mm ² / s
Range. If the kinematic viscosity of the lubricating base oil is too high, the stirring resistance will increase, and the friction coefficient in the fluid lubrication region will increase, resulting in poor fuel economy.If the kinematic viscosity is too low, the There is a problem in that wear increases in sliding parts such as a valve train, a piston, a ring, and a bearing.

2. Polyethylene glycol alkylene oxide adduct of a fatty acid partial ester and polyethylene glycol partially esterified with a fatty acid In the lubricating oil composition for an internal combustion engine of the present invention, an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol as an essential component Or at least one kind of polyethylene glycol partially esterified with a fatty acid,
As described below, the alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol is characterized by addition polymerization of a condensate of an alkylene oxide such as ethylene oxide to a free hydroxyl group of a fatty acid partial ester of a polyhydric alcohol. There is. In addition, polyethylene glycol partially esterified with a fatty acid includes a general formula RCOO
Polyoxyethylene fatty acid monoester (or polyethylene glycol fatty acid monoester) represented by (CH ₂ CH ₂ O) _n H (n is 3 or more), or both ends were not esterified at all and some hydroxyl groups were left. It is a partially esterified product of polyoxyethylene fatty acid diester (or polyethylene glycol fatty acid diester).

The polyhydric alcohol component used as the raw material for the alkylene oxide adduct of the fatty acid partial ester of the polyhydric alcohol used in the present invention has three or more hydroxyl groups in one molecule. Examples of such a polyhydric alcohol component having three or more hydroxyl groups in one molecule include glycerin, erythritol, arabitol, sorbitol,
Trimethylolpropane, ditrimethylolpropane,
Trimethylolethane, pentaerythritol, dipentaerythritol, tripentaerythritol, and sorbitol which has been dehydrated in the molecule of sorbitol, and the like may be used. One type of these may be used, or two or more types may be appropriately mixed and used. Good. Among them, sorbitan is preferably used. Having less than 3 hydroxyl groups in one molecule, such as 2
In the case of a polyhydric alcohol or the like, a low coefficient of friction cannot be obtained under lubricating conditions in which soot is mixed, and the object of the present invention cannot be achieved.

An alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol used in the present invention and a fatty acid component which is a raw material of polyethylene glycol partially esterified with a fatty acid are a saturated fatty acid having 3 to 24 carbon atoms or an unsaturated fatty acid. Fatty acids are used, and are preferably saturated or unsaturated fatty acids having 12 to 24 carbon atoms, more preferably 12 to 18 carbon atoms. Specific examples of preferred fatty acids include, for example, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, stearolic acid, and the like. If the chain length of the fatty acid is short, under lubricating conditions in which soot is mixed, a low coefficient of friction may not be obtained,
Further, the compatibility and stability in the lubricating oil may be reduced.

In the lubricating oil composition of the present invention, an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol, which is used as an essential friction-reducing component, contains ethylene oxide at a free hydroxyl group such as a fatty acid partial ester of a polyhydric alcohol. And addition polymerization of condensates such as propylene oxide. The alkylene oxide preferably has 2 to 4 carbon atoms, and ethylene oxide is preferred. The addition rate of alkylene oxide is 1 to 30 mol for ethylene oxide and 1 to 30 mol for propylene oxide per molecule of the fatty acid partial ester of polyhydric alcohol.
About 10 to 10 moles are appropriate, and preferably all are 4 moles or more. These may be added alone or as a mixture. Further, it may be random or block.

In the lubricating oil composition of the present invention, the content of the alkylene oxide adduct of the fatty acid partial ester of the polyhydric alcohol or the polyethylene glycol partially esterified with the fatty acid is 0.01 to 4 based on the total amount of the composition.
0% by weight, preferably 0.1 to 25% by weight. If the content is less than 0.01% by weight, a low coefficient of friction cannot be obtained under lubricating conditions containing soot. On the other hand, if it exceeds 40% by weight, no improvement in the friction reducing effect can be obtained, but rather the seal rubber compatibility deteriorates, which is not preferred. In addition, since the alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol is also used as a base oil, the kinematic viscosity at 100 ° C. is 0.5 to 50 mm ² / s.
It is desirable that The kinematic viscosity at 100 ° C. is 0.
If it is less than 5 mm ² / s, there is a problem in that wear is increased in sliding parts such as a valve train of an internal combustion engine, a piston, a ring and a bearing, and oil consumption may be increased. When the kinematic viscosity at exceeds 50 mm ² / s,
There is a concern that compatibility with other base oils and the like may become a problem, and further, agitation resistance increases, a friction coefficient in a fluid lubrication region increases, and fuel saving characteristics deteriorate.

Further, as the alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol, as described above in connection with the raw material components, an ethylene oxide adduct of a sorbitan fatty acid partial ester is preferably used. In particular, an ethylene oxide adduct of a saturated fatty acid having 12 to 24 carbon atoms or a partial ester of an unsaturated fatty acid having an acyl group is preferably used.
An ethylene oxide adduct of a partial ester of 2 to 18 saturated fatty acids or unsaturated fatty acids is preferably used. One type of fatty acid may be used, or two or more types may be appropriately mixed. Polyoxyethylene castor oil and polyoxyethylene hydrogenated castor oil can also be used as equivalents of alkylene oxide adducts of fatty acid partial esters of polyhydric alcohols. These can be prepared by addition polymerization of castor oil or hydrogenated castor oil with ethylene oxide. Further, the lubricating oil composition of the present invention contains, as an essential component, at least one kind of the above-mentioned alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol or polyethylene glycol partially esterified with a fatty acid in a base oil. Thus, when used as a lubricating oil for an internal combustion engine such as an automobile engine, various friction parts involving the lubricating oil exhibit a remarkable effect of low friction characteristics. In particular, a remarkable friction reducing effect can be obtained under the lubrication condition in which the suit is mixed. Therefore, the lubricating oil composition of the present invention is used for an internal combustion engine having a suit in oil. In particular, it is used for diesel engines equipped with EGR. The amount of the suit in the oil is 0.1% by weight or more, preferably in the range of 0.2 to 5.0% by weight. When the amount of the suit in the oil exceeds 5.0% by weight, there is a possibility that abrasion at the sliding portion increases. The amount of the suit in oil (% by weight) shown in the present specification was determined by ultracentrifugation (centrifugal force: 36,790 G, rotation speed: 17,500 rpm, time: 30 minutes, number of times: 3 times, temperature: 0 ° C.).

3. Other additive components The lubricating oil composition for an internal combustion engine of the present invention includes, as an essential component in a lubricating base oil, an alkylene oxide adduct of the above-mentioned fatty acid partial ester of a polyhydric alcohol, or polyethylene partially esterified with a fatty acid. At least one of the glycols
Although it contains seeds, the addition of a viscosity index improver or an ashless dispersant also has a different effect of reducing friction under lubrication conditions in which a suit is mixed.

Examples of the viscosity index improver include polymethacrylates, olefin copolymers (polyisobutylenes, ethylene-propylene copolymers), polyalkylstyrenes, styrene-butadiene hydrogenated copolymers, and styrene-maleic anhydride. Ester copolymers, star-like isoprenes, and the like can be mentioned, but in the present invention, non-dispersed olefin copolymers (polyisobutylenes, ethylene-propylene copolymers) are preferably used from the viewpoint of friction reduction effect. Further, as the molecular weight of polyisobutylene or ethylene-propylene copolymer, those having a weight average of 100,000 or more (in terms of polystyrene in GPC analysis) are particularly preferably used. The non-dispersed type does not contain oxygen or nitrogen in the molecule and has no dispersing ability. These are usually used at a ratio of 0.01 to 30% by weight based on the total amount of the composition.

As the ashless dispersant, succinimide-based dispersants,
Succinamides, benzylamines, succinates, succinates-amides, and boron-containing compounds thereof may be mentioned. In the present invention, succinimides and boron-containing succinates are used in view of a friction reducing effect. Acid imides are preferably used. The compounding amount of the succinimide and the boron-containing succinimide is 0.001 to 0.5% by weight, preferably 0.05 to 0.2% by weight, as a nitrogen amount in oil, based on the total amount of the composition. is there.

A variety of performances are required for lubricating oils for internal combustion engines, and in order to ensure performance suitable for them, various additives such as pour point depressants, metal detergents, Antioxidants, friction reducing agents, antiwear agents, extreme pressure agents, metal deactivators, rust inhibitors, defoamers, corrosion inhibitors, colorants, etc. are appropriately added within a range that does not impair the purpose of the present invention. be able to.

As the pour point depressant, generally, ethylene-
Vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol,
Examples thereof include polymethacrylate and polyalkylstyrene, and among them, polymethacrylate is preferably used. These are usually used at a ratio of 0.01 to 5% by weight.

As metal detergents, Ca, Mg, Ba,
Na and other sulfonate-based, phenate-based, salicylate-based, and phosphonate-based ones.
It is used in a proportion of from 0.5 to 5% by weight.

Examples of the antioxidant include amine antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated phenyl-α-naphthylamine; 2,6-ditert-butylphenol;
Phenolic antioxidants such as 4,4'-methylenebis- (2,6-ditert-butylphenol); sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate; and phosphorus-based oxidation such as phosphite. Inhibitors Further, zinc dithiophosphate and the like can be mentioned, and among them, amine antioxidants and phenolic antioxidants are preferably used. These are usually used at a ratio of 0.05 to 5% by weight.

Examples of the friction reducing agent include, in addition to the above-mentioned essential components, an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol or polyethylene glycol partially esterified with a fatty acid, for example, an organic molybdenum compound, a fatty acid, a higher Examples include alcohols, fatty acid esters, fatty acid partial esters, oils and fats, amines, amides, sulfurized esters, phosphate esters, phosphite esters, phosphate ester amine salts and the like. These are usually 0.0
It is used in a proportion of 5 to 3% by weight.

As the antiwear agent, zinc dithiophosphate, metal dithiophosphate (Pb, Sb, Mo, etc.), metal dithiocarbamate (Zn, Pb, Sb, Mo, etc.), metal naphthenate (Pb, etc.) are generally used. , A fatty acid metal salt (such as Pb), a boron compound, a phosphate ester, a phosphite ester, a phosphate ester amine salt and the like, and are usually used at a ratio of 0.1 to 5% by weight. Among them, zinc dialkyldithiophosphate is preferably used. In this case, the compounding amount is 0.05 to 0.1 as a phosphorus concentration.
16% by weight is preferred.

Examples of extreme pressure agents include ashless sulfide compounds, sulfurized oils and fats, phosphate esters, phosphite esters, phosphate ester amine salts, and the like.
Usually, it is used in a ratio of 0.05 to 3% by weight.

Examples of the metal deactivator include benzotriazole, a triazole derivative, a benzotriazole derivative, a thiadiazole derivative and the like, and these are usually used at a ratio of 0.001 to 3% by weight.

Examples of the rust preventive include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, paraffin oxide, and alkyl polyoxyethylene ether. Is usually 0.01 to 3
Used in percentages by weight.

Examples of the antifoaming agent include dimethylpolysiloxane and polyacrylate. Usually, a very small amount, for example, about 0.002% by weight is added. Furthermore,
In the lubricating oil composition of the present invention, other additives such as a corrosion inhibitor and a coloring agent can be used as desired.

[0032]

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not particularly limited to these examples. The friction coefficient in the examples and comparative examples was measured using a reciprocating (SRV) friction tester, and a friction test was performed under the following test conditions. Test conditions ・ Test piece (friction material): SUJ-2 ・ Plate: 24 mm diameter × 7 mm ・ Cylinder: 15 mm diameter × 22 mm ・ Temperature: 80 ° C. or 40 ° C., 50 ° C., 60 ° C., 70 ° C. ・ Load: 400 N ・Amplitude: 1.5 mm-Frequency: 50 Hz-Test time: 5 minutes

[Examples 1 to 9] In Examples 1 to 5, solvent-refined paraffinic mineral oil (viscosity at 100 ° C: 5.7 mm ² / s) was used as a lubricating base oil, based on the total amount of the composition. As an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol, an ethylene oxide adduct of sorbitan monooleate (addition of 20 mol) was added.
0% by weight, non-dispersible ethylene-
2.0% by weight of a propylene copolymer (weight-average molecular weight: 195,000), 0.07% by weight of succinimide as a nitrogen (N) amount as an ashless dispersant, and an alkyl group having primary C8 and primary C8. Zinc dialkyldithiophosphate (Zn) which is a mixture of secondary C3 / C6 (weight ratio primary / secondary = 10/9)
DTP) as phosphorus (P) in an amount of 0.09% by weight, and other additives such as a metal detergent, a viscosity index improver (dispersed polymethacrylate), a pour point depressant, and an antifoaming agent. In addition to the lubricating oil composition containing a total of 7.42% by weight of the components, the actual diesel engine was operated in advance only with the lubricating base oil, and the concentrated and collected suit was removed from 0 to 0.
A lubricating oil composition containing 3.0% by weight was prepared, and the friction coefficient in an SRV friction and wear test was measured. Table 1 shows the results. In Examples 6 to 9, similarly to Examples 1 to 5, the lubricating base oil component, the additive component, and the suit shown in Table 1 were blended in the proportions shown in the table to prepare a lubricating oil composition. Table 1 also shows the results of measuring the friction coefficient of these lubricating oil compositions in the SRV friction and wear test.

[0034]

[Table 1]

Comparative Examples 1 to 10 Lubricating oil compositions were prepared by blending the lubricating base oil components, additive components and suits shown in Table 2 in the proportions shown in the same table. Comparative Examples 1 to 10 do not contain an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol, and Comparative Examples 6 to 8 contain a polyhydric alcohol instead of the alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol. Comparative Examples 9, 10 containing sorbitan monooleate which is a fatty acid partial ester of
Uses potassium borate hydrate as a friction reducing agent.
Contains 0% by weight. Table 2 shows the results of measuring the coefficient of friction in the same manner as in Examples 1 to 9.

[0036]

[Table 2]

[Examples 10 to 14] Examples 10 to 14
Is a solvent refined paraffinic mineral oil (1
The viscosity at 00 ° C. of 5.1 mm ² / s) was used, and based on the total amount of the composition, as an alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol, an ethylene oxide adduct of sorbitan monooleate (20 mol addition) was used. ), Polyethylene glycol partially esterified with a fatty acid, polyethylene glycol monooleate, a viscosity index improver, a non-dispersible ethylene-propylene copolymer, an ashless dispersant, succinimide, and an alkyl group of a primary type. Zinc dialkyldithiophosphate (ZnDTP) which is a mixture of C8 and secondary C3 / C6 (weight ratio of primary / secondary = 10/9), and other additive components such as metal detergent, pour point depressant, A lubricating oil composition containing an antifoaming agent in the ratio shown in Table 3 was further added to the actual diesel engine in advance. Driving only with a lubricating base oil, the suits concentrating collected 3.0 lubricating oil composition weight percent blend was prepared, the friction coefficient was measured in SRV friction wear test. still,
The coefficient of friction is the average of the coefficient of friction measured at each temperature of 40 ° C, 50 ° C, 60 ° C, and 70 ° C. Table 3 shows the results.

[0038]

[Table 3]

[Comparative Examples 11 to 17] Lubricating oil compositions were prepared by blending the lubricating base oil components, additive components and suits shown in Table 4 in the proportions shown in the same table. Table 4 shows the results of measuring the coefficient of friction in the same manner as in Examples 10 to 14.

[0040]

[Table 4]

From the results of the above Examples and Comparative Examples, at least one kind of alkylene oxide adduct of a fatty acid partial ester of a specific polyhydric alcohol or polyethylene glycol partially esterified with a fatty acid was added to a lubricating base oil. Surprisingly, it was found that the lubricating oil composition contained reduced the coefficient of friction with an increase in the amount of the suit in oil in the presence of the suit in oil. With other friction reducing agents, the effect of reducing the coefficient of friction is not so significant in the presence of a suit in oil, but rather the coefficient of friction tends to increase. In addition, lubricating base oils containing at least one type of alkylene oxide adduct of a fatty acid partial ester of a specific polyhydric alcohol or polyethylene glycol partially esterified with a fatty acid, further comprise a non-dispersible ethylene glycol. -It became clear that the lubricating oil composition containing the propylene copolymer and the succinimide had an excellent effect of reducing the coefficient of friction in the presence of a suit in oil.

[0042]

The lubricating oil composition for internal combustion engines of the present invention is obtained by partially esterifying a lubricating base oil with an alkylene oxide adduct of a fatty acid partial ester of a specific polyhydric alcohol or a fatty acid as an essential component. By containing at least one kind of polyethylene glycol, a remarkable effect of being excellent in friction loss reduction under lubricating conditions in which a suit insoluble in oil is mixed is exhibited. Therefore, it can be suitably used as a lubricating oil composition for an internal combustion engine having an in-oil suit, particularly a diesel engine equipped with an exhaust gas recirculation device (EGR).

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 145/36 C10M 145/36 145/38 145/38 // C10N 30:04 C10N 30:04 40:25 40:25 (72) Inventor Satoshi Ogano 1-3-1 Nishitsurugaoka, Oimachi, Iruma-gun, Saitama Prefecture Tonen Co., Ltd. (72) Katsuya Koganei 1-3-3, Nishitsurugaoka, Oimachi, Iruma-gun, Saitama No. 1 F-term in Tonen Research Laboratory (reference) 4H104 BB44A BB44C BB47A BB47C CB14A CB14C DA02A EB02 LA02 PA41 PA42

Claims (4)

[Claims] 1. An alkylene oxide adduct of a fatty acid partial ester of a polyhydric alcohol or a fatty acid partial ester with a base oil composed of mineral oil and / or synthetic lubricating oil in an amount of 0.01 to 40% by weight, based on the total amount of the composition. A lubricating oil composition for an internal combustion engine, comprising at least one kind of polyethylene glycol which has been converted into an oil. 2. The lubricating oil composition for an internal combustion engine according to claim 1, wherein the fatty acid partial ester of the polyhydric alcohol is a sorbitan fatty acid partial ester. 3. The lubricating oil composition for an internal combustion engine according to claim 1, which is used for an internal combustion engine that discharges soot. 4. The lubricating oil composition for an internal combustion engine according to claim 3, which is used for a diesel engine equipped with an exhaust gas recirculation device (EGR).