KR102075820B1 - Lubricant oil composition for internal combustion engine - Google Patents

Abstract

This invention aims at further friction reduction and provides the lubricating oil composition for internal combustion engines which was excellent in fuel economy saving performance. (A) 0.005-0.2 mass% and (C) metal type cleaning agent as a molybdenum amount with respect to the composition whole quantity with respect to the lubricating oil base oil of kinematic viscosity in 2.0 to 5.0 mm <^2> / s at 100 degreeC. Internal combustion containing 0.01-10 mass% of 1 or more types of compounds chosen from the amino acid and / or derivative (s) which have 0.01-1 mass% and (D) a C6-C24 alkyl group, alkenyl group, or acyl group as a whole quantity basis. Lubricant compositions for engines.

Description

Lubricant composition for internal combustion engines {LUBRICANT OIL COMPOSITION FOR INTERNAL COMBUSTION ENGINE}

The present invention relates to a lubricating oil composition for an internal combustion engine having improved fuel economy.

The low fuel consumption of automobiles, which began to be triggered by the oil crisis, is still an important issue in terms of resource protection and environmental protection, and his necessity has been increasing in recent years. The fuel economy of automobiles has been improved by reducing the weight of the vehicle body, improving the combustion of the engine, and lowering the friction of the engine and the drive system. The low friction of the engine includes the improvement of the moving valve system mechanism, the reduction of the surface roughness of the sliding member, the use of a low fuel consumption lubricating oil composition (engine oil), and the like.

Among these, the use of low fuel consumption engine oil is becoming common in the market from the point which is excellent in cost-effectiveness. As a countermeasure for low fuel consumption due to engine oil, low viscosity intended to reduce friction loss under fluid lubrication conditions such as piston system and bearing part has been considered, and reduction of friction loss under mixed lubrication and boundary lubrication of moving valve system, etc. has been studied. Addition of friction reducing agents such as intended organic molybdenum compounds is proposed.

As such a fuel-saving engine oil, Patent Document 1, for example, discloses a specific additive (alkaline earth metal salicylate-based detergent, molybdenum diti) in base oil having a kinematic viscosity at 100 ° C of 2 to 8 mm ² / s and an aromatic content of 15% by mass. An engine oil composition containing a specific amount of a carbamate-based friction reducing agent, etc.) is further described in Patent Literature 2 to a lubricating oil base oil containing an ester lubricating oil base oil having a kinematic viscosity of 3 to 8 mm ² / s at 100 ° C. The lubricating oil composition for an internal combustion engine comprising a friction modifier or an ester-based or amine-based frictionless modifier and an overbased Ca salicylate is further described in Patent Literature 3. Or lubricating oil compositions for internal combustion engines which have been formulated by combining an ashless friction modifier such as aliphatic amine compounds. There is.

However, even if the molybdenum-based friction modifier increases the compounding amount, there is a limit in the friction reduction effect, there is a problem such as a precipitate is generated and unstable, and even if used in combination with an ester-based or amine-based ashless friction modifier, Further improvement was hardly confirmed. In addition, fuel economy savings required for lubricating oil are increasing in recent years, and sufficient fuel economy is still not obtained with conventional engine oils.

On the other hand, sarcosine and aspartic acid derivatives are known as ashless friction modifiers (for example, Patent Literatures 4 to 6), but also blended with a lubricating oil composition for an internal combustion engine or exhibiting synergistic effects of friction reduction by being used in combination with a molybdenum friction modifier. It is not known that one of ordinary skill in the art can predict this working effect.

Japanese Patent Publication No. 8-302378 Japanese Patent Publication No. 2005-41998 Japanese Patent Laid-Open No. 2008-106199 Japanese Patent Laid-Open No. 9-316475 Japanese Patent Laid-Open No. 2008-179669 Japanese Patent Laid-Open No. 2005-290181

The present invention solves the above problems, and an object of the present invention is to provide a lubricating oil composition for an internal combustion engine, which is capable of further reducing friction and excellent in fuel economy saving performance.

The present invention is (A) 0.005 to 0.2% by mass of (B) a molybdenum-based friction modifier based on the total amount of the composition in (B) a lubricating oil base oil having a kinematic viscosity at 100 ° C of 2.0 to 5.0 mm ² / s. 0.01-10 mass of the at least 1 type compound chosen from the amino acid and / or its derivative which have a metallic detergent based on the whole quantity of a composition as a metal amount, and (D) an alkyl group or an alkenyl group, or an acyl group of 6-24 carbon atoms. It is lubricating oil composition for internal combustion engines containing%.

Preferably, the (C) metal-based detergent contains at least a salicylate-based detergent, and has a kinematic viscosity at 100 ° C. of the lubricating oil composition for an internal combustion engine at 4.0 to 12.5 mm ² / s, furthermore, dialkyldithio. It is a lubricating oil composition for internal combustion engines which contains 0.02 to 0.2 mass% of zinc phosphate (ZnDTP) as a phosphorus amount further based on composition whole quantity.

The lubricating oil composition for an internal combustion engine of the present invention exhibits a remarkable effect of low friction coefficient and excellent fuel economy saving performance.

(A) Lube base oil

The lubricating oil base oil in the present invention is not particularly limited as long as it is a lubricating oil base oil having a kinematic viscosity of 2.0 to 5.0 mm ² / s at 100 ° C and is used as a lubricating oil base oil of a lubricating oil composition for a normal internal combustion engine, regardless of mineral oil or synthetic oil. Can be used.

It is preferable that dynamic viscosity in 100 degreeC of this lubricating oil base oil is in the range of 2.5-4.5 mm <^2> / s, More preferably, it is 3.0 mm <^2> / s or more, More preferably, it is 3.5 mm <^2> / s or more.

If the kinematic viscosity at 100 ° C. is less than 2.0 mm ² / s, the oil film formation at the lubrication point will be insufficient, resulting in poor lubricity and increased evaporation loss of the lubricant base oil. On the other hand, when it exceeds 5.0 mm <^2> / s, fuel economy saving effect will become small and low temperature viscosity characteristic will deteriorate.

In addition, in this invention, dynamic viscosity in 100 degreeC is dynamic viscosity in 100 degreeC prescribed | regulated by ASTMD-445.

Moreover, it is preferable that a viscosity index is 90 or more, and, as for the lubricating oil base oil of this invention, it is more preferable that it is 100 or more. If the viscosity index of base oil is less than 90, the viscosity in low temperature may become high and startability may deteriorate. In addition, in this invention, a viscosity index means the viscosity index measured based on JISK2283-1993.

The lubricant base oil in the present invention may be a mineral oil base oil or a mixture of two or more kinds of mineral oil base oils or a mixture of two or more kinds of synthetic base oils, as long as the conditions of the above-described lubricant base oil can be used solely as mineral oil base oils or synthetic base oils. It does not matter even if it is a mixture of mineral oil base oil and synthetic oil base oil. And two or more types of base oil mixing ratios in the said mixture can be selected arbitrarily.

As mineral oil base oil, lubricating oil fraction obtained by atmospheric distillation and reduced pressure distillation of crude oil is suitably subjected to refining treatment such as solvent depressurization, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, sulfuric acid washing and clay treatment. Lubricating oil base oils, such as a paraffin type and a naphthenic type refine | purified in combination, can be illustrated.

Examples of the synthetic base oil include poly-α-olefins (for example, polybutene, 1-octene oligomer, 1-decene oligomer, ethylene-propylene oligomer, etc.) or hydrides thereof, isobutene oligomers or hydrides thereof, isoparaffin, alkyl Benzene, alkylnaphthalene, diesters (e.g. dibutyl maleate, ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2- Ethylhexyl sebacate, etc.), copolymers of α-olefins with diesters, polyol esters (e.g., trimethylolpropane caprylate, trimethylolpropane caplargonate, pentaerythritol-2-ethylhexano And pentaerythritol pelargonate), dialkyl diphenyl ether, polyphenyl ether, and the like.

In the mineral oil base oil of the lubricating oil base oil of the present invention, a base oil having a saturated hydrocarbon content of 90% or more is preferable. In addition, in this invention, this saturated hydrocarbon powder means the value measured by ASTMD-2007.

In addition, the base oil is preferably classified into Group III or higher in the classification based on the classification of base oil by the API (American Petroleum Society), base oil obtained by isomerization of wax, and the like.

Although there is no restriction | limiting in particular about the manufacturing method of this base oil, Desulfurization and hydrocracking of the atmospheric residual oil obtained by atmospheric distillation of crude oil, fractional distillation by the set viscosity grade, or solvent-dewaxing or contact dewaxing the residual oil, if necessary, is added. It is preferable to use solvent extraction, hydrogenation, and base oil. Especially, the base oil obtained by contact dewaxing is preferable.

In the lubricating oil base oil, in addition, in recent years, the atmospheric distillation residual oil is further distilled under reduced pressure, and fractional distillation is carried out to the required viscosity grade, and then, through a process such as solvent purification and hydrogenation purification, solvent waxing is performed to produce the base oil manufacturing process. Petroleum wax isomerized lubricating oil base oil hydroisomerized by-produced petroleum wax in the dewaxing process or produced by a method of isomerizing GTL WAX (gas-to-liquid wax) produced by the Fischer Tropsch process or the like. GTL type wax isomerization lubricating oil base oil etc. which are mentioned are also included. The basic manufacturing process of the wax isomerized lubricating oil base oil in this case is the same as the manufacturing method of hydrocracking base oil.

% C _A of the base oil is not particularly limited, but is less than 3 is preferable, and more preferably 2 or less, still more preferably not more than 1, and most preferably substantially zero. When it exceeds 10, the improvement of heat resistance which is one of the objectives of this invention will become inadequate.

In addition, the% C _A means a value as measured by the method (ndM ring analysis) in conformity with ASTM D3238-85.

Moreover, although the sulfur content of the said base oil does not have a restriction | limiting in particular, 0.03 mass% or less is preferable, 0.01 mass% or less is more preferable, and it is especially preferable that it does not contain sulfur substantially. The smaller the sulfur content, the higher the degree of purification, and the less solubility of the sludge becomes.

Although there is no restriction | limiting in particular in the measuring method of sulfur, JIS K2541-1996 etc. are generally used.

(B) Molybdenum Friction Modifier

Examples of the molybdenum-based friction modifier in the present invention include dithiocarbamate molybdenum (MoDTC), dithiophosphate molybdenum (MoDTP), and the like. As dithiocarbamic acid molybdenum, the compound specifically represented by following General formula (1) can be illustrated. Moreover, as molybdenum dithiophosphate, the compound specifically represented by following General formula (2) can be illustrated.

In the formulas (1) and (2), each of R ¹ to R ⁸ individually represents a hydrocarbon group having 1 to 24 carbon atoms, a, b, c, and d are each independently any of 0 to 4, and a The integer of + b = 4 and c + d = 4 is shown.

As a preferable example of a C1-C24 hydrocarbon group represented by R <^1> -R <^8> of General formula (1) and (2), each is a C1-C24 linear or branched alkyl group, a C5-C13 cyclo An alkyl group or a linear or branched alkylcycloalkyl group, a straight or branched alkenyl group having 3 to 24 carbon atoms, an aryl group having 6 to 18 carbon atoms or a linear or branched alkylaryl group, an arylalkyl group having 7 to 19 carbon atoms, and the like Can be mentioned. The alkyl group and the alkenyl group may be primary, secondary or tertiary.

As the molybdenum-based friction modifier in the lubricating oil composition of the present invention, in addition to the above, for example, reaction products with basic nitrogen compounds such as succinimide, acidic molybdenum compounds such as molybdenum trioxide, and sulfur compounds such as hydrogen sulfide and phosphorus sulfide A phosphorus organic molybdenum complex etc. are mentioned as a preferable example.

In the lubricating oil composition of the present invention, the content of the molybdenum-based friction modifier is 0.005% by mass or more and 0.2% by mass or less, preferably 0.01% by mass or more, based on the total amount of the molybdenum element. When the content of the molybdenum-based friction modifier is less than 0.005% by mass in terms of the elemental molybdenum, a noticeable fuel economy saving effect cannot be obtained. It is not preferable that the improvement of the fuel efficiency savings commensurate with this is not obtained.

In the lubricating oil composition of the present invention, dithiophosphoric acid molybdenum and dithiocarbamate molybdenum are preferably used. However, since the synergy effect with other components can significantly improve the fuel economy saving performance from low to high temperatures, dithio Particular preference is given to molybdenum carbamic acid.

(C) metal type cleaning agent

As the metallic detergent of the present invention, any compound commonly used in lubricating oils can be used, and for example, the overbased property of oil-soluble metal salts having a linear or branched hydrocarbon group and also having an OH group and / or a carbonyl group. Compounds can be used. Furthermore, superbasic metal salts, such as alkaline earth metal sulfonates, alkaline earth metal carboxylates, alkaline earth metal salicylates, alkaline earth metal phenates, alkaline earth metal phosphonates, alkaline earth metal hydroxides or oxides, and boric acid or boric anhydrides as necessary The overbased metal salt obtained by making it can be used. Examples of alkaline earth metals include magnesium, calcium and barium, but calcium is preferable. As the overbased metal salt, it is more preferable to use an oil-soluble metal salt of a compound containing an OH group and / or a carbonyl group overbased with an alkaline earth metal borate or an alkaline earth metal carbonate. In particular, it is preferable to use alkaline earth metal salicylate from the viewpoint of excellent fuel economy, and more preferably to use alkaline earth metal salicylate overbased with alkaline earth metal borate.

The metal detergent of the present invention preferably has a base value of 50 mgKOH / g or more, more preferably 100 mgKOH / g or more, still more preferably 120 mgKOH / g or more, and particularly preferably 140 mgKOH / g or more. Moreover, it is preferable that it is 300 mgKOH / g or less, and it is more preferable that it is 200 mgKOH / g or less. When the base value is less than 50 mgKOH / g, the increase in viscosity increases the fuel economy saving deterioration and the friction reducing effect due to the addition thereof tends to be insufficient. In addition, when the base value exceeds 300 mgKOH / g, effects such as wear resistant additives are easily inhibited, and the friction reducing effect tends to be insufficient. The basic value in the present invention is a value measured by JIS K 2501 5.2.3.

The preparation method of the metal-based cleaning agent used in the present invention is arbitrary, but for example, the oil-soluble metal salt, alkaline earth metal hydroxide or oxide, boric acid or boric anhydride as necessary, alcohol, benzene, such as water, methanol, ethanol, propanol, butanol, It is obtained by making it react for 2 to 8 hours at 20-200 degreeC in presence of dilution solvents, such as toluene and xylene, and then heating to 100-200 degreeC, and removing an alcohol and a diluting solvent as needed. These detailed reaction conditions are suitably selected according to the quantity of a raw material, a reactant, etc. In addition, the detail of a manufacturing method is described in Unexamined-Japanese-Patent No. 60-116688, Unexamined-Japanese-Patent No. 61-204298, etc., for example. Since the total base value of the oil-soluble metal salt overbased with the alkaline earth metal borate prepared by the above method is usually 100 mgKOH / g or more, it can be preferably used in the lubricating oil composition of the present invention.

It is preferable that metal ratio of metal cleaning agent of this invention is 4.0 or less, 3.0 or less are more preferable, 2.0 or less are more preferable. Moreover, when metal ratio exceeds 4.0, there exists a possibility that reduction of friction torque, ie, fuel economy saving, may become inadequate. Moreover, it is preferable that metal ratio is 1.0 or more, More preferably, it is a metal type cleaning agent adjusted to 1.1 or more, More preferably, it is 1.5 or more. If the metal ratio is less than 1.0, the kinematic viscosity and the low temperature viscosity of the lubricating oil composition for an internal combustion engine are increased, which may cause problems in fuel economy and startability.

In addition, the metal ratio used in this invention is represented by the valence X metal element content (mol%) / soap content (mol%) of a metal element in a metallic detergent, and a metal element is a sulfonic acid, such as calcium and magnesium, and a soap group. Group, a phenol group, a salicylic acid group, etc. are meant.

The linear or branched hydrocarbon group of the metal detergent of the present invention is preferably an alkyl group or an alkenyl group, and such an alkyl group or alkenyl group is preferably 8 or more carbon atoms, more preferably 10 or more, still more preferably 12 or more, Moreover, 19 or less are preferable. If the carbon number is less than 8, it is not preferable because the usefulness is not sufficient. Moreover, although it may be linear or branched, it is preferable that they are linear, and these may be a primary alkyl group or an alkenyl group, a secondary alkyl group or an alkenyl group, or a tertiary alkyl group or an alkenyl group, but it is a secondary alkyl group or an alkenyl group, or 3 In the case of a class alkyl group or an alkenyl group, it is preferable that the branch position is only carbon bonded to an aromatic group.

The content of the metal-based detergent is 0.01% by mass or more, preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and 1% by mass or less, preferably in terms of metal elements, based on the total amount of the lubricating oil composition. 0.5 mass% or less, More preferably, it is 0.4 mass% or less, More preferably, it is 0.3 mass% or less, Especially preferably, it is 0.25 mass% or less, Most preferably, it is 0.22 mass% or less. When the content is less than 0.01% by mass, the friction reducing effect due to the addition thereof tends to be insufficient, and fuel economy saving, thermal and oxidation stability and cleanability of the lubricating oil composition tend to be insufficient. On the other hand, when content exceeds 1 mass%, the friction reduction effect by the addition tends to become inadequate, and the fuel economy saving property of a lubricating oil composition tends to become inadequate.

The content of the metallic detergent containing boron is, in terms of boron element, based on the total amount of the lubricating oil composition, preferably 0.01% by mass or more, more preferably 0.03% by mass or more, still more preferably 0.04% by mass or more, Especially preferably, it is 0.05 mass% or more, More preferably, it is 0.2 mass% or less, More preferably, it is 0.10 mass% or less, More preferably, it is 0.08 mass% or less, Especially preferably, it is 0.07 mass% or less. When its content is less than 0.01 mass%, the friction reduction effect by the addition tends to become inadequate, and there exists a tendency for the fuel economy saving, thermal, oxidation stability, and cleanliness of a lubricating oil composition to become inadequate. On the other hand, when content exceeds 0.2 mass%, there exists a tendency for the friction reduction effect by its addition to become inadequate, and the fuel economy saving property of a lubricating oil composition tends to become inadequate.

In addition, the boron-containing metal-based cleaning agent preferably has a ratio (MB1) / (MB2) of the weight (MB1) of the containing metal element of the cleaning agent to the weight (MB2) of the containing boron element of the cleaning agent, preferably 1 or more, More preferably, it is 2 or more, More preferably, it is 2.5 or more. When (MB1) / (MB2) becomes less than 1, it is not preferable because fuel economy may deteriorate. In addition, (MB1) / (MB2) is preferably 20 or less, more preferably 15 or less, still more preferably 10 or less, particularly preferably 5 or less. When (MB1) / (MB2) exceeds 20, it is not preferable because fuel economy may deteriorate.

(D) accounting friction modifier

In the present invention, at least one or more amino acids having an alkyl group having 6 to 24 carbon atoms or an alkenyl group or acyl group and / or derivatives thereof are contained as the ashless friction modifier. For example, the compound represented by the following general formula (3) Can be mentioned.

R ⁹ is an alkyl group or alkenyl group or acyl group having 6 to 24 carbon atoms, R ¹⁰ is an alkyl group having 1 to 4 carbon atoms or hydrogen, and R ¹¹ is hydrogen or an alkyl group having 1 to 10 carbon atoms. This alkyl group may contain a linear, branched or cyclic structure, the carbon atom may be substituted by a hetero atom, and may be modified by functional groups, such as a hydroxyl group, a carboxyl group, and an amino group. R ¹² is an alkyl group having 1 to 4 carbon atoms or hydrogen, n is 0 or 1, and X is a functional group having active hydrogen or a hydrocarbon having the functional group and a metal salt or ethanolamine salt or methoxy group of the functional group.

R ⁹ in the general formula (3) is more preferably an alkyl group or an alkenyl group or an acyl group having 11 or more carbon atoms in view of solubility in base oil. Moreover, in terms of storage stability, the carbon number of 20 or less is more preferable. Moreover, it is preferable that it is linear from a viewpoint of a friction reduction effect. As such an alkyl group, an alkenyl group, and an acyl group, For example, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexa Alkyl groups such as decyl group, heptadecyl group, octadecyl group, nonadecyl group, isosil group, heneicosyl group, docosyl group, tricosyl group and tetracosyl group (these alkyl groups may be linear or branched), hex Senyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octa Alkenyl groups (such as alkenyl groups may be linear or branched, and also dedecenyl groups, nonadesenyl groups, isocenyl groups, heneisenenyl groups, docosenyl groups, tricosenyl groups, and tetracosenyl groups) The position of the double bond is arbitrary), these alkyl groups or alke And the like can be mentioned an acyl group having a ketone group at the terminal of the group.

R ¹⁰ in the general formula (3) is more preferably an alkyl group having 4 or less carbon atoms, more preferably 3 or less carbon atoms, and particularly preferably 2 or less carbon atoms, in view of storage stability and the like.

The alkyl group of R ¹¹ may include a linear, branched or cyclic structure, the carbon atom may be substituted with a hetero atom, or may be modified with a functional group such as a hydroxyl group, a carboxyl group or an amino group. From the viewpoint of the friction reducing effect and the solubility in the base oil, an alkyl group having 2 or less carbon atoms is more preferable, more preferably 1 or less carbon atoms, and particularly preferably hydrogen.

R ¹² is more preferably an alkyl group having 4 or less carbon atoms, more preferably 3 or less carbon atoms, particularly preferably 2 or less carbon atoms, and most preferably hydrogen.

As a functional group which has active hydrogen of X in General formula (3), a hydroxyl group, an amino group, etc. are suitable. As amino groups, primary and secondary amines are preferable, and primary amines are particularly preferable. Moreover, the metal salt of a hydroxyl group is mentioned as a metal salt of the said active hydrogen group. Especially, -COX in general formula (3) has a carboxyl group.

As a hydrocarbon which has a hydroxyl group which is a functional group which has active hydrogen, specifically, for example, ethylene glycol, propylene glycol, 1, 4- butanediol, 1,2-butanediol, neopentyl glycol, 1, 6- hexanediol, 1,2 Octanediol, 1,8-octanediol, isopreneglycol, 3-methyl-1,5-pentanediol, sorbite, catechol, resorcin, hydroquinone, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol Dihydric alcohols such as F and dimer diols; Glycerin, 2- (hydroxymethyl) -1,3-propanediol, 1,2,3-butanetriol, 1,2,3-pentanetriol, 2-methyl-1,2,3-propanetriol , 2-methyl-2,3,4-butanetriol, 2-ethyl-1,2,3-butanetriol, 2,3,4-pentanetriol, 2,3,4-hexanetriol, 4 -Propyl-3,4,5-heptanetriol, 2,4-dimethyl-2,3,4-pentanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, trimethyl Trihydric alcohols such as oleethane and trimethylolpropane; Pentaerythritol, erythritol, 1,2,3,4-pentanetetrol, 2,3,4,5-hexanetetrol, 1,2,4,5-pentanetetrol, 1,3,4,5 Tetrahydric alcohols such as hexanetetrol, diglycerin and sorbitan; Pentahydric alcohols such as adonitol, arabitol, xylitol and triglycerine; Hexavalent alcohols such as dipentaerythritol, sorbitol, mannitol, iditol, inositol, dulcitol, thalos, and allose; Polyglycerol or these dehydration condensates etc. are mentioned.

Examples of the metal of the hydroxyl metal salt include alkali metals or alkaline earth metals and zinc, and examples of the alkali metal or alkaline earth metals include sodium, potassium, magnesium and calcium. Among these, alkaline earth metals and zinc are preferable from the viewpoint of improving the persistence of the friction characteristic effect.

As a metal salt, the carboxylate whose -COX of General formula (3) is a carboxyl group is preferable also in general formula (3).

As the ashless friction modifier of the present invention, at least one compound selected from the general formula (3) is preferable from the viewpoint of improving the durability of the friction characteristic effect, and only one compound selected from the general formula (3) alone It may be used or a mixture of two or more compounds may be used.

Moreover, as a suitable example of a compound represented by General formula (3), N-acyl sarcosine, among which R <^9> is an acyl group of 18 carbon atoms, R <^10> is a methyl group, R <^11> is hydrogen, X is a hydroxyl group, n is 0 N-oleoyl sarcosine or a lauroyl group in which R ⁹ is an acyl group having 12 carbon atoms, R ¹⁰ is a methyl group, R ¹¹ is hydrogen, R ¹² is hydrogen, X is a hydroxyl group, and n is 1-lauroyl-N- Methyl-β-alanine is mentioned.

Content of the said ashless friction modifier is 0.01-10 mass% on the basis of a composition whole quantity, Preferably it is 5 mass% or less, More preferably, it is 2 mass% or less. When content exceeds 10 mass%, the further improvement of the friction characteristic suitable for content is not seen, and it is unpreferable in the point which storage stability falls. On the other hand, 0.05 mass% or more is preferable on the basis of a composition whole quantity, More preferably, it is 0.1 mass%. When this content is less than 0.01 mass%, since the improvement effect of a friction characteristic is not seen, it is not preferable.

(E) antiwear agents

In addition to the above additives, it is preferable to add dialkyldithiophosphate zinc (ZnDTP) of the formula (4) to the lubricating oil composition for an internal combustion engine of the present invention as a wear inhibitor.

R ¹³ to R ¹⁶ in the formula (4) are each independently hydrogen or at least one linear or branched alkyl group having 1 to 24 carbon atoms, and this alkyl group may be primary, secondary or third It may be class.

In the present invention, these dialkyldithiophosphates may be used alone or in combination of two or more thereof. However, zinc dithiophosphate (primary ZnDTP) or secondary having a primary alkyl group may be used. Zinc dithiophosphate containing a alkyl group (secondary ZnDTP) is preferable, and zinc dithiophosphate of a secondary alkyl group is particularly preferable because of its high wear resistance.

In the lubricating oil composition of the present invention, the content of zinc dialkyldithiophosphate is preferably 0.02 to 0.2% by mass, more preferably 0.03 to 0.1% by mass, based on the total amount of the composition. When this phosphorus amount is less than 0.02 mass%, abrasion resistance and high temperature cleanliness are not enough, and when it exceeds 0.2 mass%, catalyst poisoning of an exhaust gas catalyst will become remarkable and it is unpreferable.

Lubricating oil compositions for internal combustion engines of the present invention include other additives, such as viscosity index improvers, pour point depressants, antioxidants, antiwear agents or extreme pressure agents, friction reducers, dispersants, rust inhibitors, if necessary, within the scope of not impairing the object of the present invention. , Surfactants or anti-emulsifiers, antifoaming agents and the like can be appropriately blended.

For example, as a viscosity index improver, a non-dispersion type viscosity index improver and a dispersion type viscosity index improver can be used, Specifically, a non-dispersion type or a dispersion type polymethacrylate, an olefin copolymer, polyisobutene, polystyrene, Ethylene-propylene copolymers, styrene-diene copolymers and hydrides thereof and the like can be used. Although their weight average molecular weight is generally 5,000 to 1,000,000, in order to further improve fuel economy, the viscosity index improver having a weight average molecular weight of 100,000 to 1,000,000, preferably 200,000 to 900,000, particularly preferably 400,000 to 800,000 is used. It is desirable to. Moreover, especially in this invention, the ratio of the structural unit represented by following General formula (5) is 30-90 mol%, the ratio of the structural unit represented by following General formula (6) is 0.1-50 mol%, and the hydrocarbon backbone ratio is 0.18. The viscosity index improver which is a poly (meth) acrylate type viscosity index improver which is the following is preferable for the fuel efficiency improvement.

In addition, formula (5) in R ¹⁷ is a hydrogen or a methyl group, R ¹⁸ is R ¹⁹ of hydrocarbon group of a linear or branched chain having 6 or less carbon atoms, the formula (6) represents a hydrogen or a methyl group, R ²⁰ is It is a C16 or more linear or branched hydrocarbon group.

In addition, the viscosity index improver preferably has a PSSI (Permanent Shear Stability Index) in the diesel injector method of 30 or less. When PSSI exceeds 30, shear stability is bad, and there exists a possibility that the fuel economy of an initial stage may deteriorate in order to maintain the kinematic viscosity and HTHS viscosity after use more than fixed.

In addition, "PSSI in the diesel injector method" referred to here is ASTM D6278-02 (Test Method for Shear Stability of Polymer Containing Fluids Using) based on ASTM D6022-01 (Standard Practice for Calculation of Permanent Shear Stability Index). a permanent shear stability index of a polymer, calculated on the basis of data measured by a European Diesel Injector Apparatus.

As the pour point depressant, for example, a polymethacrylate polymer, an alkylated aromatic compound, a fumarate-vinyl acetate copolymer, an ethylene-vinyl acetate copolymer, or the like suitable for the lubricating oil base oil to be used can be used.

As the clean dispersant, a succinic acid imide, a benzylamine, an alkyl polyamine, a polybuteneamine or a modified product of a boron compound or sulfur compound thereof, an alkenylsuccinic acid ester, or the like can be used.

It is preferable that this clean dispersing agent is a mono type or bis type succinic acid imide, and its bis type succinic acid imide is more preferable. Moreover, it is especially preferable that it is bis type succinic acid imide which is boron-free.

Moreover, it is preferable that this clean dispersing agent is molecular weight 1000 or more, More preferably, it is 5000 or more, More preferably, it is 7000 or more, More preferably, it is preferable that it is 9000 or more. Moreover, it is preferable that it is molecular weight 30000 or less, It is preferable that it is 25000 or less, It is more preferable that it is molecular weight 20000 or less. When the molecular weight is 1000 or less, the cleanliness may be insufficient. On the other hand, when the molecular weight exceeds 30000, the fuel economy savings of the engine oil composition may be greatly deteriorated.

The content of the clean dispersant is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, still more preferably 1.0 to 8% by mass based on the total amount of the engine oil composition. When content of a clean dispersing agent is less than 0.1 mass%, cleanliness may become inadequate, On the other hand, when it exceeds 15 mass%, the fuel economy savings of an engine oil composition may deteriorate significantly.

Moreover, it is preferable that N content of a clean dispersing agent is 0.1 or more, More preferably, it is 0.3 or more, More preferably, it is 0.4 or more, More preferably, it is preferable that it is 0.5 or more. Moreover, it is preferable that it is 2.0 or less, It is preferable that it is 1.0 or less, It is more preferable that it is 0.8 or less. If the N content is 0.1 or less, the cleanliness may be insufficient. On the other hand, if the N content is more than 2.0, the fuel economy savings of the engine oil composition may be greatly deteriorated.

As antioxidant, if it is generally used for lubricating oils, such as a phenolic compound and an amine compound, all can be used, For example, Alkylphenols, such as 2, 6- di-tert- butyl- 4-methylphenol, Methylene-4 Bisphenols such as, 4-bis (2,6-di-tert-butyl-4-methylphenol), naphthylamines such as phenyl-α-naphthylamine, dialkyldiphenylamines, phenothiazines, and the like. Can be used

Examples of the extreme pressure additive and the antiwear agent include phosphorus-based compounds such as phosphate esters, phosphorous acid esters, and salts thereof, and sulfur-based compounds such as disulfides, sulfide olefins, and sulfide fats and oils.

As the rust inhibitor, for example, alkenylsuccinic acid, alkenylsuccinic acid esters, polyhydric alcohol esters, petroleum sulfonates, dinonylnaphthalenesulfonates, and the like can be used.

As the corrosion inhibitor, for example, a benzotriazole-based, thiadiazole-based or imidazole-based compound can be used.

As the antifoaming agent, silicone compounds such as dimethylsilicone and fluorosilicone can be used, for example.

Although the addition amount of these additives is arbitrary, on the basis of composition whole quantity, content of an antifoamer is 0.0005 to 0.01 mass%, content of a viscosity index improver is 0.05-20 mass%, content of a corrosion inhibitor is 0.005 to 0.2 mass%, and other additives Content is about 0.05-10 mass%, respectively.

Kinematic viscosity of the 100 ℃ of an internal combustion engine lubricating oil composition of the present invention is 4.0mm ² / s is preferably, more preferably and most preferably 6.0mm ² / s, more preferably at least 6.1mm ² / s or more, or more is 6.2mm ² / s and above, is also 12.5mm ² / s or less is preferable, more preferably from 9.3mm ² / s or less, more preferably 8.5mm ² / s or less. The kinematic viscosity at 100 ° C herein refers to the kinematic viscosity at 100 ° C specified in ASTM D-445. If the kinematic viscosity of the 100 ℃ 4.0mm ² / s is less than a concern has not achieve the low-temperature viscosity and sufficient fuel saving performance required if the concerned result in insufficient lubricity and exceeds 12.5mm ² / s.

Moreover, it is preferable that dynamic viscosity in 40 degreeC of a lubricating oil composition is 4-50 mm <^2> / s, Preferably it is 40 mm <^2> / s or less, More preferably, it is 35 mm <^2> / s or less. The kinematic viscosity at 40 ° C is preferably 15 mm ² / s or more, more preferably 18 mm ² / s or more, even more preferably 20 mm ² / s or more, particularly preferably 22 mm ² / s or more, most preferably Preferably it is 25 mm <^2> / s or more. The kinematic viscosity at 40 ° C herein refers to the kinematic viscosity at 40 ° C specified in ASTM D-445. When the kinematic viscosity of a 40 ℃ case 4mm ² / s is less than it is apprehended result in insufficient lubricity, exceeding 50mm ² / s, there is a fear not achieve the low-temperature viscosity and sufficient fuel saving performance required.

The viscosity index of the lubricating oil composition is 120 or more, preferably 400 or less, preferably 190 or more, more preferably 200 or more, particularly preferably 230 or more, most preferably 240 or more. When the viscosity index is less than 120, there is a concern that it is difficult to improve fuel economy while maintaining the HTHS viscosity of 150 ° C. In addition, when the viscosity index exceeds 400, the evaporability may deteriorate, and there may be a problem due to insufficient solubility of the additive and lack of compatibility with the sealing material.

In order to prevent the problem of low viscosity and provide fuel economy while maintaining durability, HTHS viscosity ("HTHS viscosity" is also called "high temperature high shear viscosity") at 150 degreeC is high, and it is 40 degreeC on the other hand. Although it is effective to lower the kinematic viscosity in 100 degreeC, the kinematic viscosity in 100 degreeC, and HTHS viscosity in 100 degreeC, it was very difficult to satisfy all these requirements with the conventional lubricating oil.

It is preferable that HTHS viscosity in 100 degreeC of a lubricating oil composition is 5.5 mPa * s or less, More preferably, it is 5.0 mPa * s or less, More preferably, it is 4.7 mPa * s or less, Especially preferably, it is 4.5 mPa * s or less, Most preferably, it is 4.4 mPa * s or less. Moreover, Preferably it is 3.0 mPa * s or more, More preferably, it is 3.5 mPa * s or more, Especially preferably, it is 4.0 mPa * s or more, Most preferably, it is 4.1 mPa * s or more. HTHS viscosity in 100 degreeC said by this invention shows the high temperature high shear viscosity in 100 degreeC prescribed | regulated by ASTMD4683. When HTHS viscosity in 100 degreeC is less than 3.0 mPa * s, there exists a possibility that a lack of lubricity may be caused, and when it exceeds 5.5 mPa * s, there exists a possibility that the required low temperature viscosity and sufficient fuel economy saving performance may not be acquired.

Moreover, it is preferable that ratio (HTHS viscosity in HTHS viscosity / 100 degreeC in 150 degreeC) of HTHS viscosity in 150 degreeC and HTHS viscosity in 100 degreeC of the lubricating oil composition of this invention is 0.45 or more, More preferably, it is 0.475 or more, More preferably, it is 0.50, More preferably, it is 0.515 or more, Especially preferably, it is 0.53 or more. If the said ratio is less than 0.45, there exists a possibility that a required low temperature viscosity and sufficient fuel economy saving performance may not be acquired.

Example

Although the content of this invention is demonstrated further more concretely by an Example and a comparative example below, this invention is not limited to these examples at all.

(Examples 1 to 7, Comparative Examples 1 to 7)

(A) Lube base oil

A hydrocracking lubricating oil base oil having the following properties was used in combination in the proportions shown in Table 1. (A-1) a kinematic viscosity at 40 ℃ 19.6mm ² / s, kinematic viscosity at 100 ℃ 4.2mm ² / s, viscosity index 122, sulfur less than 10ppm, 80.7% C _P,% C _N 19.3,% C _A 0

(A-2) Kinematic Viscosity at 40 ° C 13.5mm ² / s, Kinematic Viscosity at 100 ° C 3.2mm ² / s, Viscosity Index 112, Less than 10ppm Sulfur,% C _P 72.6,% C _N 27.4,% C _A 0

The following additives were added to the lubricating oil base oil in the proportions shown in Table 1 to prepare lubricating oil compositions.

(B) Molybdenum Friction Modifier

Dithiocarbamic acid molybdenum: In the formula ^(1), R 1 to R ⁴ is 8 carbon atoms or an alkyl group, a and b are 2, the concentration of the molybdenum element of 13 10 mass%, 11 mass% sulfur

(C) metal type cleaning agent

(C-1) Overbasic Ca salicylate: Metal ratio 2.3, C14-C18 of an alkyl group, Ca content 6.2 mass%, The base is 180 mgKOH / g

(C-2) Overbasic boric acid Ca salicylate: Metal ratio 2.5, C14-C18 of the alkyl group, Ca content 6.8 mass%, B content 2.7 mass%, Base value 190 mgKOH / g

(C-3) Overbasic boric acid Ca salicylate: Metal ratio 1.5, C14-28 carbon number of an alkyl group, 5.0 mass% of Ca content, 1.8 mass% of B content, 140 mgKOH / g of bases

(D) accounting friction modifier

(D-1) Oleoyl Sarcosine

(D-2) N-lauroyl-N-methyl-β-alanine

(D-3) N-lauroyl sarcosine

(D-4) Oleoyl-N-methyl-β-alanine

(D-5) Alkylamine Ethylene Oxide Adduct

(D-6) oleylamine

(D-7) Glycerine Monooleate

(D-8) oleyl amide

(D-9) Orail Urea

(E) other additives

(E-1) ZnDTP: secondary alkyl group, carbon number 4 and 6, Zn content 7.8% by mass, P content 7.2% by mass, S content 15% by mass

(E-2) Non-dispersion PMA Viscosity Index Improver (Mw = 380,000, PSSI = 25)

(E-3) Polybutenyl succinimide: molecular weight 9000, N content 0.6 mass%

(E-4) antioxidant, antifoaming agent (dimethylsilicone), etc.

About the manufactured lubricating oil composition, the motoring friction test was done on condition of the following, and friction torque was measured. Average friction torque of each lubricating oil composition was calculated, and the improvement rate based on the average friction torque of Comparative Example 1 (= average friction torque of Comparative Examples 2 to 7 of Comparative Examples 1 to 7) Average friction torque). The obtained result is shown in% in Table 1 with the physical property of a lubricating oil composition.

(Exam conditions)

Engine used: 4-cylinder in 1800cc, roller rocker arm type engine

Oil temperature: 100 ℃

RPM: 1000rpm

From the above results, the combination of the molybdenum-based friction modifier with an ashless friction modifier that does not have a C6-C24 hydrocarbon group, a nitrogen atom, and a carboxyl group in the molecule did not show any friction reducing effect (Comparative Examples 2 to 6). The lubricating oil composition which uses a C6-C24 hydrocarbon group, a nitrogen atom, and an ashless friction modifier which has a carboxyl group shows synergistically remarkable friction reduction effect, The lubricating oil composition for internal combustion engines of this invention has a low friction coefficient, and a fuel economy saving performance It is clear that this outstanding effect is exerted.

The lubricating oil composition for an internal combustion engine of the present invention can be suitably used as fuel saving engine oil such as fuel saving gasoline engine oil and fuel saving diesel engine oil.

Claims (5)

(A) In lubricating oil base oil whose kinematic viscosity in 100 degreeC is 2.0-5.0 mm <^2> / s,
(B) 0.005 to 0.2% by mass of molybdenum-based friction modifier, based on the total amount of the composition,
(C) 0.01-1 mass% of metal type detergent as a metal amount based on composition whole quantity, and
(D) The lubricating oil composition for internal combustion engines containing 0.01-10 mass% of 1 or more types of compounds represented by following General formula (3).

[Wherein R ⁹ is an acyl group having 6 to 24 carbon atoms,
R ¹⁰ is an alkyl group having 1 to 4 carbon atoms or hydrogen,
R ¹¹ is hydrogen or an alkyl group having 1 to 10 carbon atoms, the alkyl group may be linear, branched, or may include a cyclic structure, and the carbon atom may be substituted with a hetero atom, or It may be modified with a hydroxyl group, a carboxyl group, or an amino group,
R ¹² is an alkyl group having 1 to 4 carbon atoms or hydrogen,
n is 0 or 1,
X is a functional group having active hydrogen, a hydrocarbon having the functional group, a metal salt or an ethanolamine salt of the functional group, or a methoxy group] The lubricating oil composition for an internal combustion engine according to claim 1, wherein the metal cleaning agent (C) contains at least a salicylate cleaning agent. The lubricating oil composition for an internal combustion engine according to claim 1 or 2, wherein the kinematic viscosity at 100 ° C is 4.0 to 12.5 mm ² / s. The lubricating oil composition for an internal combustion engine according to claim 1 or 2, further comprising 0.02 to 0.2 mass% of dialkyldithiophosphate (ZnDTP) as a phosphorus amount based on the total amount of the composition. 4. The lubricating oil composition for an internal combustion engine according to claim 3, further comprising 0.02 to 0.2% by mass of zinc dialkyldithiophosphate (ZnDTP), based on the total amount of the composition.