JP2003155492A - 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 reduces the poisoning of an NOx sorption catalyst, also reduces a deposit on an intake valve, and is suited for use in an engine in which gasoline is directly injected into the cylinder. SOLUTION: This lubricant composition for an internal combustion engine contains (A) a base oil comprising mineral and/or synthetic oils having a kinematic viscosity (100 deg.C) of 3.5-10.0 mm<2> /s, a total sulfur content of at most 0.005 mass %, and a total aromatics content of at most 10 mass %, 0.01-0.2 mass % (in terms of the nitrogen), based on the entire weight of the composition, (B) polybutenyl succinimide and/or a derivative thereof, at most 0.3 mass % (in terms of the sulfur) (C) zinc thiophosphate, 0.1-5.0 mass % (D) phenolic and/or aminic ashless antioxidants, and 0.1-0.3 mass % (in terms of the alkaline earth metal) (E) alkaline earth metal cleaner and is substantially free from (F) a viscosity index improver.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lubricating oil composition for an internal combustion engine, and more particularly to a lubricating oil composition for an internal combustion engine which is suitable for use in a gasoline direct injection engine.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of environmental regulations for automobiles, especially from the viewpoint of prevention of global warming, reduction of carbon dioxide emission by fuel saving or exhaust gas purification has been emphasized. Improvements have been implemented. As one of the promising technologies for fuel saving, introduction of gasoline direct injection engine with higher combustion efficiency is being promoted (eg Okano et al .: Development of direct injection gasoline engine, TOYOTA Technical Review, 50 , 2 (200
0)). NOx storage catalysts are used in exhaust gas purification systems for gasoline direct-injection engines because they are difficult to achieve with conventional three-way catalysts (for example, N. Miyoshi et al.,: Development of New Concept
Three-Way Catalyst for Automotive lean-Burn Engine
s, SAE Paper 950809), it has been reported that this NOx storage catalyst is susceptible to poisoning by sulfur contained in gasoline and engine oil (eg Suzuki et al .: Analysis of poisoning mechanism of NOx storage catalyst and its Improvement, TOYOTA Technical Review, 44, 27 (1996)), and low sulfur of gasoline, as well as improvement of evaporation of engine oil and low sulfur are required. Furthermore, in gasoline direct-injection engines, deposit accumulation at gasoline intake system ports or valves is a problem (eg SW Morris: The Evaluati
on of Performance Enhancing Fluids and The Develop
ment of Measurement and Evaluation techniques in
The Mitsubishi G-DI Engine, SAE Paoer 1999-01-149
6), measures are also required.

[0003]

However, in consideration of the evaporation characteristics and low sulfur of engine oil, it is necessary to reduce the catalyst poisoning of the NOx storage type catalyst and to reduce the deposit in the gasoline direct injection engine. There have been few reports on engine oil focused on, and it seems that it has not been used in the market. The present invention has been made from the above viewpoint, and provides a lubricating oil composition for an internal combustion engine, which is capable of suppressing catalyst poisoning of a NOx storage catalyst and also reducing intake valve deposits, and which is suitable for a gasoline direct injection engine. The purpose is to do.

[0004]

[Means for Solving the Problems] The present inventors have proposed a base oil in which a deposit is hard to form, a soot which is considered to be a core substance of the deposit, a viscosity index improver which is considered to contribute to the growth of the deposit, and further to suppress the deposit. As a result of repeated intensive studies to optimize various compounding additives, it was found that a composition containing a specific base oil and a specific additive in a specific amount can solve the above problems, and the present invention Has been completed. That is, the present invention provides (A) 100
A group consisting of mineral oil and / or synthetic oil having a kinematic viscosity of 3.5 to 10.0 mm ² / s at 0 ° C, a total sulfur content of 0.005 mass% or less and a total aromatic content of 10 mass% or less. Based on the total amount of the composition, (B) polybutenyl succinimide and / or its derivative was added to the oil in an amount of 0.
0.1 to 0.2% by mass, (C) zinc dithiophosphate in an amount of 0.3% by mass or less in terms of sulfur element, and (D) a phenol-based ashless antioxidant and / or an amine-based ashless antioxidant. 1
To 5.0% by mass, (E) an alkaline earth metal-based detergent is contained in an amount of 0.1 to 0.3% by mass in terms of an alkaline earth metal element, and (F) a viscosity index improver is substantially contained. The lubricating oil composition for internal combustion engines is characterized by not containing it.

The lubricating oil composition for an internal combustion engine of the present invention preferably has a kinematic viscosity at 100 ° C. of 5.6 to 16.3 mm ² / s. In the lubricating oil composition for internal combustion engines of the present invention, the component (E) has a total base number of 150 to 35.
It is preferably 0 mg KOH / g basic calcium salicylate. In the lubricating oil composition for internal combustion engines of the present invention, the base oil has a kinematic viscosity at 100 ° C. of 1.
It is preferably composed of one or more selected from poly-α-olefins of 8 to 40 mm ² / s and hydrides thereof. The lubricating oil composition for an internal combustion engine of the present invention is preferably for an internal combustion engine equipped with an exhaust gas purifying device loaded with a NOx storage catalyst. The lubricating oil composition for an internal combustion engine of the present invention is preferably for a gasoline direct injection engine.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The component (A) in the lubricating oil composition for internal combustion engines of the present invention is a specific base oil composed of mineral oil and / or synthetic oil. As the mineral oil, specifically, a lubricating oil fraction obtained by distilling crude oil under atmospheric pressure and vacuum distillation is used for solvent degassing, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining. Examples thereof include paraffin-based or naphthene-based oils and normal paraffins, which have been purified by one or a combination of two or more purification treatments such as sulfuric acid washing and clay treatment. Those that have been subjected to solvent refining and hydrorefining are generally used, but advanced hydrocracking processes and GTL that can further reduce aromatics
It is more preferable to use a wax produced by an isomerization method of gas (gas to liquid wax).

Specific examples of the synthetic oil include poly-α-
Olefin (for example, 1-octene oligomer, 1-decene oligomer, ethylene-propylene oligomer, etc.), poly-α-olefin hydride, isobutene oligomer, isobutene oligomer hydride, isoparaffin, alkylbenzene, alkylnaphthalene, diester (for example, Ditridecyl glutarate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, dioctyl sebacate, etc., polyol ester (for example, trimethylol propane caprylate, trimethylol propane pelargonate, trimethylol propane isostearinate and other trimethylol propane esters) Pentaerythritol such as pentaerythritol 2-ethylhexanoate and pentaerythritol pelargonate Ester), polyoxyalkylene glycols, dialkyl ethers, polybutene, and polyphenyl ether. As the component (A) in the present invention, an arbitrary mixed oil of one or two or more selected from these mineral oils and synthetic oils can be used.

The total sulfur content of the component (A) is required to be 0.005% by mass or less, the preferable range is 0.002% by mass or less, and particularly preferably substantially no sulfur ( That is, it is preferably 0.0005 mass% or less or not contained at all). As a result, it is possible to prevent caulking of the intake valve and the like and to reduce the sulfur content of the composition, so that it is possible to suppress catalyst poisoning of the NOx storage catalyst. The aromatic content of the component (A) is required to be 10% by mass or less, the preferable range is 6% by mass or less, and the particularly preferable range is 2%.
It is not more than mass%. The aromatic content of component (A) is 10
If the content exceeds 10% by mass, suppress coking of the intake valve, etc., even when using new oil (not yet used after being manufactured by the lubricating oil composition of the present invention), when soot is mixed, or when used for a long time. It is not preferable because it cannot be done. The total aromatic content is the aromatic fraction (aromat) measured according to the method specified in ASTM D2549.
ics fraction) content is meant.

The kinematic viscosity of component (A) at 100 ° C. must be 3.5-10.0 mm ² / s,
The preferable range is 4.0 to 9.0 mm ² / s.
If the kinematic viscosity at 100 ° C. is less than 3.5 mm ² / s, the base oil will evaporate too much, which may cause poisoning of the catalyst and adverse effects on the viscosity increase. It is easy to cause coking to the intake valve etc. due to, and the kinematic viscosity at 100 ° C is 10.0 mm
If it exceeds ² / s, not only is power loss due to viscous resistance increased, fuel efficiency is inferior, but also contact time with high temperature parts such as the intake valve becomes longer and coking tends to occur, which is not preferable. .

When a mixed oil is used as the component (A),
As long as the kinematic viscosity, total sulfur content, and total aromatic content of the mixed oil at 100 ° C. are within the ranges specified above,
A base oil in which one of the mixed oils falls outside this range, for example,
A base oil having a kinematic viscosity of more than 10 mm ² / s at 100 ° C., a base oil having a total sulfur content of more than 0.005 mass%, or a base oil having an aromatic content of more than 10 mass% is appropriately mixed and used. You may. In the present invention, 100 ° C
Kinematic viscosity at the 1.8~40mm ² / s, preferably, 2.8~20mm ² / s, more preferably, 3.5
It is preferable to use a base oil consisting of one or two or more selected from poly-α-olefins and hydrides thereof of 10 mm ² / s. However, the base oil has a kinematic viscosity range defined in the present invention (that is, 3.5 to 10.0 mm ² / s (10
0 ° C.)) or, in the case of mixed oils, adjust to such a range. (A)
The viscosity index of the component is not particularly limited, but it is preferably 110 or more, and particularly preferably 120 or more. By using a base oil having a high viscosity index, it is possible to further suppress coking and obtain a multigrade engine oil composition having excellent fuel economy and low temperature viscosity characteristics.

The component (B) is polybutenyl succinimide and / or its derivative. Examples of the polybutenyl succinimide include polybutenyl succinimide represented by the following general formula (1) or (2).

[0012]

[Chemical 1]

In the general formula (1) or (2), the PIB
Represents a polybutenyl group having a number average molecular weight of 900 to 3500, and is obtained from polybutene obtained by polymerizing a high-purity isobutene or a mixture of 1-butene and isobutene with a boron fluoride catalyst or an aluminum chloride catalyst, The polybutene mixture usually contains 5 to 100 mol% of those having a vinylidene structure at the terminal. In addition, in order to obtain an excellent sludge suppression effect,
n is an integer of 2 to 5, preferably 3 or 4. Also,
It is particularly preferable that the polybutene, which is caused by the catalyst in the production process, has a small amount of residual fluorine and chlorine sufficiently removed by an appropriate method such as an adsorption method or sufficient washing with water. The content of halogen elements is 50
The content is preferably not more than mass ppm, more preferably not more than 10 mass ppm, further preferably not more than 5 mass ppm, and particularly preferably not more than 1 mass ppm.

The method for producing the succinimide represented by the general formula (1) or (2) is not particularly limited. For example, polybutene obtained by chlorinating the above polybutene, preferably polybutene from which chlorine and fluorine are sufficiently removed, is mixed with maleic anhydride to 100 to 2
Polybutenyl succinic acid obtained by reacting at 00 ° C.,
A method of reacting with a polyamine such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine can be used. When producing bissuccinimide,
The polybutenyl succinic acid may be reacted in a double amount (molar ratio) of the polyamine. When producing monosuccinimide, the polybutenyl succinic acid and the polyamine may be reacted in an equal amount (molar ratio). Good. Among these, polybutenyl bissuccinimide is preferable because it has excellent soot dispersibility and can further suppress coking when soot is mixed.

In the component (B), as the derivative of polybutenyl succinimide, a compound represented by the above general formula (1) or (2) can be used, for example, a boron compound or an oxygen-containing organic compound. To neutralize a part or all of the remaining amino group and / or imino group by reacting with, or an amidated compound. Examples of the boron compound that acts on the compound of the general formula (1) or (2) include boric acid, borate salts, and borate esters. Specific examples of boric acid include orthoboric acid, metaboric acid, and tetraboric acid. Examples of the borate include alkali metal salts of boric acid, alkaline earth metal salts, ammonium salts, and the like, and more specifically, for example, lithium metaborate, lithium tetraborate, lithium pentaborate, perborate. Lithium borate such as lithium; sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate and other sodium borate; potassium metaborate, potassium tetraborate, Potassium pentaborate, potassium hexaborate,
Potassium borate such as potassium octaborate; calcium metaborate, calcium diborate, tricalcium tetraborate,
Calcium borate such as pentacalcium tetraborate and calcium hexaborate; magnesium borate such as magnesium metaborate, magnesium diborate, trimagnesium tetraborate, pentamagnesium tetraborate and magnesium hexaborate;
And ammonium metaborate, ammonium tetraborate,
Examples thereof include ammonium borate and ammonium octaborate. Examples of the borate ester include esters of boric acid and an aliphatic alcohol preferably having 1 to 6 carbon atoms, and more specifically, for example, monomethyl borate, dimethyl borate, trimethyl borate, and borate. Monoethyl borate, diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, dibutyl borate, tributyl borate and the like. The succinimide derivative on which the above boron compound acts is preferably used because it has excellent heat resistance and oxidation stability.

Specific examples of the oxygen-containing organic compound which acts on the compound of the general formula (1) or (2) include, for example,
Formic acid, acetic acid, glycolic acid, propionic acid, lactic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid,
C1-C30 monocarboxylic acids such as tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, oleic acid, nonadecanoic acid, eicosanoic acid; oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid Polycarboxylic acids having 2 to 30 carbon atoms such as acids or their anhydrides, or ester compounds; 2 to 6 carbon atoms
Alkylene oxide; hydroxy (poly) oxyalkylene carbonate and the like. By causing such an oxygen-containing organic compound to act, for example, when a part or all of the amino group or imino group in the compound of the general formula (1) or (2) becomes a structure represented by the following general formula (3). Presumed.

[0017]

[Chemical 2]

R ¹ is a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, an alkenyl group, an alkoxy group, or --O--.
(R ² O) _m H represents a hydroxy (poly) oxyalkylene group, R ² represents an alkylene group having 1 to 4 carbon atoms, and m represents an integer of 1 to 5.

Of these, polybutenyl bissuccinimide containing as a main component a compound obtained by acting these oxygen-containing organic compounds on all amino groups or imino groups is preferably used because of its excellent sludge dispersibility. Such a compound is, for example, (n-1) based on 1 mol of the compound of the formula (1).
It is obtained by reacting a molar oxygen-containing organic compound.
The succinimide derivative treated with such an oxygen-containing organic compound is excellent in soot dispersibility, and is preferably one treated with hydroxy (poly) oxyalkylene carbonate.

The content of the component (B) in the present invention is 0.01% by mass in terms of nitrogen element based on the total amount of the composition.
It is necessary to be 0.2% by mass, and the preferable range is 0.05 to 0.18% by mass. When the content of the component (B) is less than 0.01% by mass, it is difficult to suppress coking, while the content of the component (B) is 0.
If it exceeds 2% by mass, the low-temperature viscosity characteristics are inferior and the desired multigrade engine oil cannot be obtained, which is not preferable.

The component (C) in the present invention is zinc dialkyldithiophosphate. Preferred examples of the component (C) include compounds represented by the following general formula (4).

[0022]

[Chemical 3]

In the general formula (4), R ^{11 to} R ¹⁴ each independently have 2 to 18 carbon atoms, preferably 3 to 10 carbon atoms.
Is a linear or branched alkyl group. Specific examples of the alkyl group include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group. Examples thereof include a group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group and an octadecyl group, which may be linear or branched. Further, these may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group. When introducing the alkyl group, a mixture of α-olefins may be used as a raw material. In this case, the component (C) is a mixture of zinc dialkyldithiophosphate having an alkyl group having a different structure.

In the composition of the present invention, the content of the component (C) is required to be 0.3 mass% or less in terms of elemental sulfur based on the total amount of the composition, and 0.26 mass% or less. It is preferably present, and more preferably 0.2 mass% or less. The content is preferably 0.02 mass% or more, more preferably 0.06 mass% or more. Content of component (C) is 0.02% by mass
If less than, there is a fear of deterioration of the wear prevention performance, while, when the content exceeds 0.3 mass%, deterioration of the composition at high temperature oxidation is promoted, and there is a concern that the intake system deposit increases. Further, there is a possibility that the poisoning of the NOx storage type catalyst due to sulfur may be accelerated and the exhaust gas purification performance may be adversely affected.

The component (D) in the present invention is a phenol ashless antioxidant and / or an amine ashless antioxidant. Specific examples of the phenol-based ashless antioxidant include 4,4′-methylenebis (2,6-di-t).
ert-butylphenol), 4,4'-bis (2,6
-Di-tert-butylphenol), 4,4'-bis (2-methyl-6-tert-butylphenol),
2,2'-methylenebis (4-ethyl-6-tert-
Butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-
Butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6
-Di-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-nonylphenol), 2,
2'-isobutylidene bis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2, 6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-
tert-butylphenol, 2,6-di-tert-
α-dimethylamino-p-cresol, 2,6-di-t
ert-Butyl-4 (N, N'-dimethylaminomethylphenol), 4,4'-thiobis (2-methyl-6-
tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol),
2,2′-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4-hydroxy-)
5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, 2,2′-thio-diethylenebis [3- (3,5-di-tert-butyl) -4-Hydroxyphenyl) propionate], octyl-3- (3,3
5-di-tert-butyl-4-hydroxyphenyl)
Propionate, tridecyl-3- (3,5-di-te
rt-Butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis [3- (3,5-
Di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-te
rt-Butyl-4-hydroxyphenyl) propionate, and mixtures thereof. In addition, among these, the phenolic compounds having a molecular weight of 240 or more are
It is more preferably used because it has a high decomposition temperature and exerts its effect even under higher temperature conditions.

Specific examples of the amine-based ashless antioxidants include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, dialkyldiphenylamine, N, N'-diphenyl-p-phenylenediamine and mixtures thereof. Can be mentioned. Examples of the alkyl group include linear or branched alkyl groups having 1 to 20 carbon atoms.

The lower limit of the content of the component (D) in the present invention is 0.1% by mass, preferably 0.3% by mass, based on the total amount of the composition, while the upper limit thereof is 5% by mass. %, Preferably 2.5% by mass. Its content is 0.
If the amount is less than 1% by mass, the composition of the present invention is not preferable because there is a concern that the intake system deposit may increase. On the other hand, if the content exceeds 5% by mass, the amount of the intake system deposit may be increased with respect to the content. It is not preferable because the suppressing effect cannot be sufficiently obtained.

The component (E) in the present invention is an alkaline earth metal detergent. Examples of the alkaline earth metal-based detergents include alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates. The alkaline earth metal sulfonate has, for example, a molecular weight of 300 to 1500, preferably 40.
It is an alkaline earth metal salt of an alkylaromatic sulfonic acid obtained by sulfonation of an alkylaromatic compound of 0 to 700, particularly a magnesium salt and / or a calcium salt, and a calcium salt is preferably used. Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid. As the petroleum sulfonic acid, generally used is one obtained by sulfonation of an alkyl aromatic compound of a lubricating oil fraction of mineral oil, so-called mahogany acid produced as a by-product during the production of white oil, or the like. Further, as the synthetic sulfonic acid, for example, an alkylbenzene having a linear or branched alkyl group, which is obtained as a by-product from an alkylbenzene production plant which is a raw material of a detergent or obtained by alkylating a polyolefin into benzene, is sulfonated. Or a sulfonated product of alkylnaphthalene such as dinonylnaphthalene. As the sulfonating agent for sulfonating these alkyl aromatic compounds, for example, fuming sulfuric acid or sulfuric anhydride is usually used.

Examples of the alkaline earth metal phenates include alkylphenols, alkylphenol sulfides, alkaline earth metal salts of Mannich reaction products of alkylphenols, particularly magnesium salts and / or calcium salts. Specifically, the following general formula (5)-
The thing represented by (7) can be mentioned.

[0030]

[Chemical 4]

[0031]

[Chemical 5]

[0032]

[Chemical 6]

In the general formulas (5), (6) and (7), R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ and R ²⁶ may be the same or different and each has 4 carbon atoms. ~ 3
0, preferably 6-18 linear or branched alkyl groups, M ¹ , M ² and M ³ each represent an alkaline earth metal, preferably calcium and / or magnesium, and x is 1 or 2 Indicates.

Specific examples of the alkyl group represented by R ^{21 to} R ²⁶ include butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, Tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group , And a triacontyl group. These may be linear or branched.
These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

As the alkaline earth metal salicylate,
For example, the alkaline earth metal salts of alkylsalicylic acid, especially the magnesium and / or calcium salts. Specific examples include compounds represented by the following general formula (8).

[0036]

[Chemical 7]

In the general formula (8), R ²⁷ has 4 to 4 carbon atoms.
30, preferably 6-18 linear or branched alkyl groups, M ⁴ represents an alkaline earth metal, preferably calcium and / or magnesium. Specific examples of the alkyl group represented by R ²⁷ include a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group,
Decyl group, undecyl group, dodecyl group, tridecyl group,
Tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group And the like, which may be linear or branched. These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

Alkaline earth metal sulfonates, alkaline earth metal phenates and alkaline earth metal salicylates are prepared by directly adding magnesium or magnesium directly to the above alkyl aromatic sulfonic acid, alkylphenol, alkylphenol sulfide, Mannich reaction product of alkylphenol, alkylsalicylic acid and the like. And / or reacting with an alkaline earth metal base such as an alkaline earth metal oxide or hydroxide of calcium, or once replacing with an alkaline earth metal salt such as a sodium salt or potassium salt. Neutral (normal salt) alkaline earth metal sulfonates, neutral (normal salt) alkaline earth metal phenates and neutral (normal salt) alkaline earth metal salicylates obtained by
Alternatively, it can be obtained by heating a neutral alkaline earth metal sulfonate, a neutral alkaline earth metal phenate, a neutral alkaline earth metal salicylate, and an excess of an alkaline earth metal salt or an alkaline earth metal base in the presence of water. Of basic alkaline earth metal sulfonates, basic alkaline earth metal phenates and basic alkaline earth metal salicylates; further of neutral alkaline earth metal sulfonates, neutral alkaline earth metal phenates and neutral alkaline earth metal salicylates An overbased (superbasic) alkaline earth metal sulfonate obtained by reacting a hydroxide of an alkaline earth metal with carbon dioxide or boric acid in the presence of
Also included are overbased (ultrabasic) alkaline earth metal phenates and overbased (ultrabasic) alkaline earth metal salicylates.

In the present invention, the above-mentioned neutral alkaline earth metal salt, basic alkaline earth metal salt, overbased (superbasic) alkaline earth metal salt, a mixture thereof and the like can be used. Metal-based detergents are usually commercially available in a state of being diluted with a light lubricating base oil or the like, and are available, but the metal content thereof is generally 1.0 to 20% by mass, preferably 2%. The thing of 0.0-16 mass% is used. Although the total base number of the alkaline earth metal-based detergent used in the present invention is arbitrary, one having a total base number of 500 mgKOH / g or less, preferably 150 to 450 mgKOH / g is usually used. The total base number is JIS K2501 (1992)
7. "Petroleum products and lubricants-Neutralization number test method" Means the total base number measured by the perchloric acid method in accordance with In the present invention, of these alkaline earth metal-based detergents, it is preferable to use alkaline earth metal salicylates, and the lower limit of the total base number is 150 mg.
KOH / g is preferred, 160 mg KOH /
More preferably g. On the other hand, the upper limit of the total base number is preferably 350 mgKOH / g, 3
More preferably, it is 00 mgKOH / g, 25
Particularly preferred is 0 mg KOH / g. By using an alkaline earth metal salicylate having a total base number in the above range, it is possible to obtain a composition capable of suppressing intake system deposits even when soot is mixed in or when lubricating oil deteriorates.

The content of the component (E) in the lubricating oil composition for an internal combustion engine of the present invention is 0.1 to 0.3% by mass in terms of alkaline earth metal element, based on the total amount of the composition. Is required, and more preferably 0.15 to 0.25% by mass. When the amount of the component (E) is less than 0.1% by mass, the effect of suppressing intake system deposits is poor, while (E)
When the content of the component exceeds 0.3% by mass, ash is accumulated inside the engine to deteriorate the cleanability, and there is a concern that the NOx storage catalyst may be adversely affected.

The lubricating oil composition for internal combustion engines of the present invention comprises (F)
Substantially free of viscosity index improver. The term "substantially free from the component (F)" means that the content is not included at all, or even if it is included, it is a small amount compared with the usual content (2.0 to 10% by mass). The content is 1.0 mass% or less, more preferably 0.5 mass% or less, based on the total amount of the composition. If the content of the component (F) exceeds 1.0% by weight, the amount of intake system deposits produced tends to increase rapidly.

Examples of the (F) viscosity index improver include:
Examples thereof include non-dispersion type or dispersion type viscosity index improvers. Specific examples of the non-dispersion type viscosity index improver include alkyl acrylates having 1 to 18 carbon atoms and 1 to 18 carbon atoms.
Homo- or copolymer of one or more monomers (F-1) selected from alkyl methacrylate, olefin having 2 to 20 carbon atoms, styrene, methylstyrene, maleic anhydride ester, maleic anhydride amide, etc. Examples thereof include hydrides.

As the dispersion type viscosity index improver, dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate,
Diethylaminoethyl methacrylate, 2-methyl-5
-Vinyl pyridine, morpholino methyl methacrylate,
Morpholinoethyl methacrylate, N-vinylpyrrolidone, etc., and one or more kinds of monomers (E
-2) a homopolymer or copolymer thereof, or a hydride thereof obtained by introducing an oxygen-containing group, or a component (F-1) and a component (F-
Examples thereof include copolymers with the component 2), hydrides thereof, and the like. When the above-mentioned (F-1) component and (F-2) component are copolymerized, the molar ratio of the (F-1) component and the (F-2) component is
Generally, it is about 80:20 to 95: 5.

In addition to the above-mentioned additives, the lubricating oil composition for internal combustion engines of the present invention may contain, if necessary, any additives generally used in lubricating oils. Examples of such additives include friction reducing agents, (B)
An ashless dispersant other than the components, an antiwear agent other than the component (C),
Other than the component (D), there may be mentioned antioxidants, pour point depressants, corrosion inhibitors, rust preventives, demulsifiers, metal deactivators, defoamers, and additives such as colorants.

As the friction reducing agent, for example, carbon number 6 to
Examples thereof include amine compounds, fatty acid esters, fatty acid amides, fatty acid metal salts and the like having 30 linear or branched, preferably linear hydrocarbon groups, or organic molybdenum compounds, and any mixture thereof. As the linear or branched hydrocarbon group having 6 to 30 carbon atoms,
Specifically, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, Alkyl groups such as henicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group (these alkyl groups may be linear or branched); hexenyl Group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, nonadecenyl group,
Alkenyl groups such as icosenyl group, henicosenyl group, docosenyl group, tricosenyl group, tetracosenyl group, pentacocenyl group, hexacosenyl group, heptacosenyl group, octacosenyl group, nonacocenyl group, triacontenyl group (these alkenyl groups may be linear or branched. And the position of the double bond is arbitrary); and the like.

The amine compound has 6 to 3 carbon atoms as described above.
Examples thereof include aliphatic monoamines having 0 hydrocarbon group, aliphatic polyamines, and alkylene oxide adducts of these aliphatic amines. Examples of the fatty acid ester include esters of the above-mentioned fatty acid having a hydrocarbon group having 6 to 30 carbon atoms with an aliphatic monohydric alcohol or an aliphatic polyhydric alcohol. The fatty acid amide has 6 carbon atoms as described above.
Examples thereof include amides of a fatty acid having a hydrocarbon group of about 30 and an aliphatic monoamine or an aliphatic polyamine. Examples of the fatty acid metal salt include alkaline earth metal salts (magnesium salt, calcium salt, etc.) and zinc salt of the above-mentioned fatty acid having a hydrocarbon group having 6 to 30 carbon atoms. Of these, fatty acid esters are preferred, and specific preferred examples include glycerin monooleate and sorbitan monooleate.

As the organic molybdenum compound, for example,
Examples thereof include molybdenum dithiocarbamate compounds and molybdenum dithiophosphate. A molybdenum dithiocarbamate compound which is excellent in oxidation stability and a friction reducing effect is more preferable, and specific examples thereof include those represented by the general formula (9).

[0048]

[Chemical 8]

In the general formula (9), R ³¹ , R ³² , R
³³ and R ³⁴ each independently represent a hydrocarbon group (specifically, an alkyl group or an alkylaryl group having 2 to 18 carbon atoms), and Y ¹ , Y ² , Y ³ and Y ⁴ are each individually Shows S (sulfur atom) or O (oxygen atom). The alkyl group includes a primary alkyl group, a secondary alkyl group or a tertiary alkyl group, which may be linear or branched. As the preferred alkyl group, specifically, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group,
Examples thereof include alkyl groups such as octyl group, decyl group, dodecyl group and tridecyl group (these alkyl groups may be linear or branched). Specific examples of preferred alkylaryl groups include alkylaryl groups such as a butylphenyl group and a nonylphenyl group (these alkyl groups may be linear or branched).

Specific preferred molybdenum dithiocarbamate compounds include molybdenum sulfide diethyldithiocarbamate, molybdenum dipropyldithiocarbamate sulfide, molybdenum dibutyldithiocarbamate sulfide, molybdenum dipentyldithiocarbamate sulfide,
Molybdenum sulfide dihexyl dithiocarbamate, molybdenum dioctyl dithiocarbamate, molybdenum sulfide didecyl dithiocarbamate, molybdenum sulfide didodecyl dithiocarbamate, molybdenum sulfide ditridecyl dithiocarbamate, sulfide molybdenum di (butylphenyl) dithiocarbamate, molybdenum di (nonylphenyl) dithiocarbamate, sulfide Oxymolybdenum diethyl dithiocarbamate, oxymolybdenum dipropyl dithiocarbamate, oxymolybdenum dibutyl dithiocarbamate, oxymolybdenum dipentyl dithiocarbamate, oxymolybdenum dihexyl dithiocarbamate, oxymolybdenum dioctyl dithiocarbamate, oxymolybdenum didecyl dithiocarbamate Molybdenum dithiocarbamate, such as sulfurized oxymolybdenum didodecyl dithiocarbamate, sulfurized oxymolybdenum ditridecyl dithiocarbamate, sulfurized oxymolybdenum di (butylphenyl) dithiocarbamate, sulfurized oxymolybdenum di (nonylphenyl) dithiocarbamate (each alkyl group may be linear Branched form may be used) and a mixture thereof.

In the present invention, the content of the above-mentioned friction reducing agent is usually 0.01 to 10% by mass, based on the total amount of the composition,
The content of molybdenum dithiocarbamate containing molybdenum in the molecule, molybdenum dithiophosphate, etc. is preferably 0.1 to 3% by mass, but the total amount of the composition is 0.01 to 10 in terms of elemental sulfur. It is desirable to limit the content to 0.20% by mass, preferably 0.02 to 0.15% by mass. By limiting the sulfur content as described above, it is possible to reduce the total sulfur content of the composition while maintaining the effect of suppressing intake system deposits and the effect of reducing friction, and reduce the adverse effect on the NOx storage catalyst. You can

Examples of the ashless dispersant other than the component (B) include benzylamine or polyamine having an alkyl group or an alkenyl group having 40 to 400 carbon atoms and derivatives thereof. Examples of these derivatives include those obtained by reacting the above-mentioned succinimide, benzylamine, polyamine and the like with the above-mentioned boron-containing compound, the above-mentioned oxygen-containing organic compound and the like. (C)
As the antiwear agent other than the components, for example, phosphoric acid ester, phosphorous acid ester and amine salts thereof, phosphorus compounds such as zinc dialkylthiophosphate, zinc dialkylphosphate, zinc dialkyldithiocarbamate, disulfides, sulfurized olefins And sulfur compounds such as sulfurized fats and oils, and an arbitrary mixture thereof.

Examples of the antioxidant other than the component (D) include alkyldithiocarbamic acid ester and the like. Examples of the corrosion inhibitor include benzotriazole-based, tolyltriazole-based, thiadiazole-based, and imidazole-based compounds. Examples of the pour point depressant include various polymethacrylates compatible with lubricating base oils, olefin copolymers and the like.

Examples of the rust preventive agent include polyhydric alcohol ester, petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester. Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and polyoxyethylene alkylnaphthyl ether.

Examples of the metal deactivator include imidazoline, pyrimidine derivatives, alkylthiadiazole,
Mercaptobenzothiazole, benzotriazole or a derivative thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and β- (o -Carboxybenzylthio) propionnitrile and the like. Examples of the defoaming agent include silicone, fluorosilicone, fluoroalkyl ether and the like.

When these additives are contained in the lubricating oil composition for an internal combustion engine of the present invention, their content is usually based on the total amount of the composition, and in the ashless dispersant other than the component (B),
0.01-10% by mass, 0.01-5% by mass for antiwear agents other than the component (C), 0.01-10% by mass for antioxidants other than the component (D), and as a pour point depressant , 0.
It is 01 to 5 mass%. Corrosion inhibitors, rust preventives and demulsifiers are selected in the range of 0.01 to 5% by mass, metal deactivators in the range of 0.005 to 1% by mass, and defoamers in the range of 0.0005 to 1% by mass. .

In the lubricating oil composition for internal combustion engines of the present invention, the sulfur content of the (A) base oil is 0.005 as described above.
Not only limited to not more than mass%, but (C) zinc dithiophosphate-derived sulfur content is 0.3 mass% or less, preferably 0.2 mass% or less, and the above sulfur-containing addition such as molybdenum dithiocarbamate By limiting the total content of the agents to 0.4 mass% or less, preferably 0.35 mass% or less, particularly preferably 0.3 mass% or less, in terms of sulfur element, based on the total amount of the composition, the composition Can have a sulfur content of 0.5% by mass or less, preferably 0.4% by mass or less, more preferably 0.35% by mass or less, and further contains sulfur as a diluent oil usually blended with the additive. By using an extremely small amount (for example, the component (A)), the total sulfur content in the composition can be reduced to 0.3 mass% or less, and the intake system deposit suppressing effect and other performance can be maintained. Shitsu , It is possible to further reduce the adverse effect on the NOx storage catalyst or the like.

[0058]

EXAMPLES The contents of the present invention will be described more specifically below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Examples 1 to 9 and Comparative Examples 1 to 8 As shown in Table 1, the lubricating oil composition for an internal combustion engine of the present invention (Examples 1 to 1)
9) and, as a comparison, lubricating oil compositions (Comparative Examples 1 to 8) not satisfying the requirements of the present invention were prepared. The obtained composition (new oil), a composition in which 1% by mass of carbon black manufactured by Mitsubishi Chemical Corporation was mixed with this new oil, and an ISOT test (according to JIS K 2514, 165.5 ° C., 72 hours) of the composition ), The deteriorated oil forcibly deteriorated by the panel caulking test (Federal 791 test method Tenta
live Standard Method 3462
-T, panel temperature 320 ° C., oil temperature 100 ° C., splashing bar operation 15 seconds to stop 45 seconds, test time 3 hours), and measure the weight of the deposit on the panel after the test. The lubricating oil composition was evaluated. The evaluation results are shown in Table 1.
And shown in Table 2. Under the conditions of the panel caulking test as described above, it was recognized that there is a certain degree of correlation between the weight of the deposit and the amount of intake system deposit produced, particularly in the case of carbon black mixed oil or deteriorated oil.

[0060]

[Table 1]

[0061]

[Table 2]

From the results shown in Table 1, in the lubricating oil compositions for internal combustion engines (Examples 1 to 9) of the present invention, each component is within the claimed range and the coke in the panel caulking test is obtained regardless of the viscosity grade. It can be seen that the amount of king produced is as small as 50 mg or less. In addition, the amount of carbon black mixed oil that is assumed to be mixed with soot and other contaminants under actual use conditions and forcedly deteriorated oil is as low as 100 mg or less. Excellent performance in the range from new oil to post-use oil assuming actual use conditions. have. In particular, when a poly-α-olefin hydride is used as the component (A), when an alkaline earth metal salicylate is used as the component (E), when no component (F) is contained,
And when the content of the component (C) is 0.2 mass% or less in terms of sulfur element conversion, the effect of suppressing the amount of coking is excellent.

On the other hand, from the results shown in Table 2, when the kinematic viscosity of the component (A) does not satisfy the requirements of the present invention (Comparative Examples 1 and 2), poly-α, which is a synthetic oil having excellent oxidation stability, is used. −
Despite the use of olefin hydride
King production increases. When the content of the component (B) is less than the specified amount of the present invention (Comparative Example 4), when the component (D) is not included (Comparative Example 6), the amount of the (F) component exceeds the specified amount of the present invention. In the case (Comparative Example 7) and the content of the component (E) is less than the regulation of the present invention (Comparative Example 8), the
The amount of king generation tends to increase remarkably. further,
When the sulfur content and aromatic content of the component (A) do not meet the requirements of the present invention (Comparative Example 3) and the amount of the component (C) exceeds the requirements of the present invention (Comparative Example 5), the amount of coking produced Is significantly increased, and the sulfur content in the composition is high, which may cause an adverse effect on the NOx storage catalyst.

[0064]

EFFECTS OF THE INVENTION According to the present invention, a lubricating oil composition for internal combustion engines, which is unlikely to cause coking at high temperatures and has a low sulfur content, can be obtained, in particular, even when soot is mixed in or after deterioration. Can be suppressed. Therefore, it is extremely effective for an internal combustion engine equipped with an exhaust gas purification device loaded with a NOx storage catalyst, particularly for a gasoline direct injection engine. In addition, other lubricating oil compositions for internal combustion engines that easily mix soot and easily cause coking at high temperatures, for example, vehicles equipped with EGR, vehicles equipped with three-way catalysts, vehicles equipped with oxidation catalysts, diesel engines, gas engines, motorcycles It can also be preferably used as a lubricating oil for an internal combustion engine such as a 4-cycle engine. Further, according to the present invention, 5W-20, 5W-30, 10W-40, 1
It is possible to provide a multi-grade lubricating oil composition for an internal combustion engine such as 0W-20.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10M 133/12 C10M 133/12 133/56 133/56 135/24 135/24 135/30 135/30 137 / 10 137/10 A 139/00 139/00 A 159/22 159/22 // C10N 10:04 C10N 10:04 20:00 20:00 Z 20:02 20:02 30:04 30:04 30: 08 30:08 40:25 40:25 F-term (reference) 4H104 BA07A BB05C BB34C BE02C BE07C BF03C BG13C BG16C BH07C BJ05C CA01A DA02A DB06C EA02A EA02Z EA21A EA22C EB02 FA02 LA02 LA04 PA41

Claims (6)

[Claims] 1. (A) The kinematic viscosity at 100 ° C. is 3.5.
~ 10.0 mm ² / s, total sulfur content 0.005
(B) Polybutenyl succinimide and / or its derivative is added to a base element consisting of a mineral oil and / or a synthetic oil having a total aromatic content of 10% by mass or less and a nitrogen element as a composition total amount basis. 0.01 to 0.2% by mass in terms of conversion, (C) 0.3% by mass or less of zinc dithiophosphate in terms of sulfur element, (D) Phenol-based ashless antioxidant and / or amine-based ashless oxidation 0.1 to 5.0 mass% of inhibitor, (E) 0.1 to 0.3 mass% of alkaline earth metal-based detergent in terms of alkaline earth metal element, and (F) viscosity A lubricating oil composition for an internal combustion engine, which contains substantially no index improver. 2. The composition has a kinematic viscosity at 100 ° C. of 5.6 to.
The lubricating oil composition for an internal combustion engine according to claim 1, wherein the lubricating oil composition has a diameter of 16.3 mm ² / s. 3. The total base number of the component (E) is 150 to 150.
The lubricating oil composition for an internal combustion engine according to claim 1, which is 350 mgKOH / g of basic calcium salicylate. 4. The base oil comprises one or more selected from poly-α-olefins and hydrides thereof having a kinematic viscosity at 100 ° C. of 1.8 to 40 mm ² / s. The lubricating oil composition for internal combustion engines according to claim 1. 5. An internal combustion engine equipped with an exhaust gas purifying device, which is loaded with a NOx storage catalyst.
The lubricating oil composition for internal combustion engines according to any one of to 4. 6. The lubricating oil composition for an internal combustion engine according to claim 1, which is for a gasoline direct injection engine.