JP2001164283A - 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 having long life without rapidly increasing viscosity of the lubricating oil by finely dispersing solid impurities insoluble in the oil into the oil. SOLUTION: This lubricating oil composition for the internal-combustion engine is characterized in that the lubricating oil composition is obtained by formulating (A) succinimide having >=2,500 weight-average molecular weight in an amount of 0.03-0.12 wt.% expressed in terms of nitrogen, (B) a basic alkaline earth metal sulfonate having 200-450 mgKOH/g whole base value as a metal cleaner in an amount the whole base value derived from the metal cleaner is within the range of 6-18 mgKOH/g and (C) a dialkyl zinc dithiophosphate in an amount of 0.04-0.5 wt.% expressed in terms of phosphorus based on the total weight of the composition to a lubricating base oil composed of a mineral oil and/or a synthetic oil. The lubricating oil composition for the internal-combustion engine is further characterized by comprising a basic alkaline earth metal salicylate or a basic alkaline earth metal phenate having 100-350 mgKOH/g whole base value as a metal cleaner so that the amount ratio of the salicylate or the phenate based on the total metal cleaners is at most 40% or 20% respectively expressed in terms of the whole base value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition for an internal combustion engine, and more particularly, to dispersing solid impurities such as soot inevitably generated when a diesel engine is driven in oil to reduce the viscosity of the lubricating oil. The present invention relates to a lubricating oil composition for a long-life internal combustion engine, especially a diesel engine, which does not increase rapidly.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine, in addition to lubrication of various sliding parts such as a piston ring and a cylinder liner, bearings of a crankshaft and a connecting rod, and a valve mechanism including a cam and a valve lifter, cooling of the engine is performed. Lubricating oils are used for the purpose of clean dispersion of combustion products and combustion products, and further, to prevent rust and corrosion. As described above, lubricating oils for internal combustion engines are required to have various performances, and in recent years, advanced performances have been required in accordance with high performance, high output, and severe operating conditions of internal combustion engines. . Therefore, lubricating oils for internal combustion engines are required to satisfy such required performances, for example, ashless dispersants, metal detergents, antiwear agents (antiwear agents), friction reducers (friction modifiers), antioxidants Various additives such as agents are blended. Heretofore, ashless dispersants and metal detergents have been used in combination as lubricating oils for internal combustion engines as detergent and dispersants. As the ashless dispersant, generally, polyalkenyl or polyalkylsuccinimide, polyalkenyl or polyalkylsuccinamide,
Polyalkenyl or polyalkyl succinic esters, polyalkenyl or polyalkyl benzylamines, and borated products thereof are used. As the metal detergent, phenates, sulfonates, salicylates, phosphonates of alkali metals and alkaline earth metals, and overbased products thereof are generally used. By the way, in a diesel engine, a large amount of solid impurities insoluble in a lubricating oil such as a combustion residue or soot is generated on a combustion mechanism as compared with a gasoline engine, and these are mixed into the lubricating oil or the lubricating system. I have. When the mixing amount increases, a sudden increase in the viscosity of the lubricating oil and the lubricating portion and a clogging phenomenon in the lubricating system occur, which hinders smooth lubrication management and necessitates a short-term oil renewal. I have. Therefore, in order to solve such a problem, various measures and measures have conventionally been taken to eliminate solid impurities insoluble in lubricating oil such as combustion residues or soot. There are two methods. The first method is to aggregate and coarsen solid impurities and capture and remove them with an oil filter installed in a lubricating oil circulation system. Specifically, for example, calcium having a specific total base number Phenate, solid impurity cohesive diesel engine oil containing magnesium sulfonate having a specific total base number and alkenyl succinimide, etc. (Japanese Patent Publication No. 3-29839,
JP-A-5-295382), a diesel engine using a lubricating oil composition to which two kinds of calcium sulfonates having a specific total base number, calcium phenate having a specific total base number, alkenyl succinimide and zinc dithiophosphate are added. A lubrication system (Japanese Patent Publication No. 6-60317) and the like have been proposed. In a similar technical concept, a diesel containing thiophosphonic acid hydroxyethyl ester or the like is blended in order to moderately disperse and remove combustion residues with an oil filter. Engine oils and the like (Japanese Unexamined Patent Publication Nos. 4-1293 and 5-93197), a land-based diesel engine oil in which dispersibility is suppressed by a combination of succinimide and long-chain zinc dialkyldithiophosphate to remove solid impurities ( JP-A-5-230485) and the like have been proposed. On the other hand, the second method is different from the first method in that the basic idea is different from that of the first method in that aggregation of solid impurities such as soot mixed in oil is prevented, and the solid impurities themselves are finely dispersed in oil. More specifically, for example, a diesel engine oil containing calcium phenate, alkenyl succinimide and specific zinc dialkyldithiophosphate having a specific base number capable of controlling the particle size of soot (Japanese Unexamined Patent Application Publication No. 9
JP-A-1655591) and a lubricant containing a transition metal salt (Japanese Patent Publication No. 1-50)
No. 1396) has been proposed. Further, as applied to a diesel engine equipped with a diesel particulate filter (DPF), zinc dialkyldithiophosphate, calcium carbonate overbased calcium salicylate and / or calcium borate overbased calcium salicylate having a specific total base number, and A low phosphorus and low ash type diesel engine oil containing a specific amount of a boric acid-modified succinimide having a specific molecular weight (Japanese Patent Application Laid-Open No. 9-111275) has been proposed. However, despite these proposals, there is no lubricating oil system for diesel engines that has a sufficiently long service life yet, and in particular, prevents the aggregation of solid impurities such as soot by the second method, and makes the solid impurities themselves finer. There are few lubricating oils for long-life internal combustion engines (especially diesel engines) which are dispersed in oil and the viscosity of the lubricating oil does not increase rapidly.

[0003]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a long-life lubricating oil in which solid impurities insoluble in oil are finely dispersed in the oil so that the viscosity of the lubricating oil does not increase rapidly. Another object of the present invention is to provide a lubricating oil composition for an internal combustion engine.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above-mentioned problems, and as a result, a lubricating base oil comprising a mineral oil and / or a synthetic oil, a succinimide having a specific weight average molecular weight, A basic alkaline earth metal sulfonate, or a metal detergent in which a basic alkaline earth metal sulfonate is combined with a basic alkaline earth metal salicylate, and zinc dialkyldithiophosphate are blended at specific ratios. As a result, it has been found that solid impurities such as soot in oil are finely dispersed and the viscosity of lubricating oil does not increase rapidly, and the present invention has been completed based on this finding.
That is, according to the present invention, (A) succinimide having a weight average molecular weight of 2500 or more based on the total amount of the composition is added to a lubricating base oil composed of mineral oil and / or synthetic oil in an amount of 0.03 as nitrogen. And (B) a basic alkaline earth metal sulfonate having a total base number of 200 to 450 mg KOH / g as a metal detergent, and a total base number derived from the metal detergent of 6 to 18 mg KOH / g. And (C) a zinc dialkyldithiophosphate in an amount of 0.04 to 0.5% by weight as a phosphorus amount. You. Further, according to the present invention, as a metal detergent, a basic alkaline earth metal salicylate or phenate having a total base number of 100 to 350 mgKOH / g is further used. The lubricating oil composition for an internal combustion engine is provided, wherein the lubricating oil composition is blended in an amount of at most 40% or 20% on a value basis.

[0005] As described above, the present invention relates to a lubricating base oil,
A lubricating oil composition for an internal combustion engine, wherein a specific amount of a succinimide having a specific weight average molecular weight, a metal detergent such as a basic alkaline earth metal sulfonate, and zinc dialkyldithiophosphate are blended. However, preferred embodiments thereof include the following. The lubricating oil composition for an internal combustion engine as described above, wherein the internal combustion engine is a diesel engine that produces soot in oil. The above lubricating oil composition for an internal combustion engine, wherein the alkaline earth metal is calcium. The metal detergent is 1 based on the total base number derived from the metal detergent.
The lubricating oil composition for an internal combustion engine as described above, which is a combination of 0 to 60% basic alkaline earth metal sulfonate and 0 to 40% basic alkaline earth metal salicylate. When the metal detergent has a total base number of 7 based on the metal detergent,
The lubricating oil composition for an internal combustion engine as described above, which is a combination of 5 to 62.5% of a basic alkaline earth metal sulfonate and 25 to 37.5% of a basic alkaline earth metal salicylate. The metal detergent is 1 based on the total base number derived from the metal detergent.
The lubricating oil composition for an internal combustion engine described above, which is a combination of 00 to 80% basic alkaline earth metal sulfonate and 0 to 20% basic alkaline earth metal phenate. The metal detergent is 9 based on the total base number derived from the metal detergent.
The lubricating oil composition for an internal combustion engine described above, which is a combination of 9.5 to 94% of a basic alkaline earth metal sulfonate and 0.5 to 6% of a basic alkaline earth metal phenate. The lubricating oil composition for an internal combustion engine as described above, wherein the compounding amount of the succinimide having a weight average molecular weight of 2500 or more is at least 0.06% by weight or more as the amount of nitrogen. The lubricating base oil contains the compound, and further,
Selected from the group of friction reducing agents, antioxidants, viscosity index improvers, pour point depressants, rust inhibitors, corrosion inhibitors, defoamers, and other additive components required for lubricating oil compositions for internal combustion engines The lubricating oil composition for an internal combustion engine according to any of the above, which comprises at least one additive component.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (1) Lubricating oil base oil In the lubricating oil composition for an internal combustion engine of the present invention, mineral oil and / or synthetic oil is used as the lubricating oil base oil. The lubricating base oil is not particularly limited, and any lubricating base oil that is generally used can be used. In other words,
There is a mineral oil, a synthetic oil, or a mixed oil thereof. The mineral oil is obtained, for example, by treating a lubricating oil raw material derived from normal or reduced pressure distillation of a paraffinic, intermediate or naphthenic crude oil with an aromatic extraction solvent such as phenol, furfural or N-methylpyrrolidone. Solvent-refined raffinate, hydrotreated oil obtained by contacting hydrogen under hydrogenation conditions in the presence of a hydrotreating catalyst such as cobalt or molybdenum using silica-alumina as a lubricating oil raw material as a carrier, hydrocracking Hydrocracked oil obtained by contacting with hydrogen under severe cracking reaction conditions in the presence of a catalyst, isomerized oil obtained by contacting wax with hydrogen under isomerization conditions in the presence of a catalyst for isomerization, Alternatively, a lubricating oil fraction obtained by combining a solvent refining step with a hydrotreating step, a hydrocracking step, an isomerization step, and the like can be mentioned. In particular, a high viscosity index mineral oil obtained by a hydrocracking step or an isomerization step can be mentioned as a preferable one. In any of the production methods, steps such as a dewaxing step, a hydrofinishing step, and a clay treatment step can be arbitrarily adopted by a conventional method. Specific examples of the mineral oil include light neutral oil, medium neutral oil, heavy neutral oil, bright stock, and the like. The base oil can be adjusted by appropriately mixing so as to satisfy required properties.

[0007] Synthetic oils include, for example, poly α-olefins, α-olefin oligomers, polybutenes, alkylbenzenes, polyol esters, dibasic acid esters,
Examples thereof include polyoxyalkylene glycol, polyoxyalkylene glycol ether, and silicone oil. Each of these base oils can be used alone or
More than one species can be used in combination, and mineral oil and synthetic oil may be used in combination. The base oil used in the present invention usually has a kinematic viscosity at 100 ° C. of ^{2 to 20} mm ² / s, and a preferable kinematic viscosity is in a range of 3 to 15 mm ² / s. If the kinematic viscosity of the lubricating base oil is too high, the low-temperature viscosity deteriorates and the friction loss increases. On the other hand, if the kinematic viscosity is too low, there is a problem that the wear increases in sliding parts such as the piston ring and the valve mechanism.

(2) Succinimide In the lubricating oil composition for an internal combustion engine of the present invention, succinimide is used as an essential component (A). As the succinimide, for example, a compound represented by the general formula [I]

[0009]

Embedded image

A monopolyalkenyl or monopolyalkylsuccinimide represented by the general formula [II]:

[0011]

Embedded image

And a bispolyalkenyl or bispolyalkylsuccinimide represented by the formula: In the general formulas [I] and [II], R ¹ , R ³ and R
⁴ is an oligomer residue of an α-olefin having about 2 to 8 carbon atoms or a hydride thereof, and R ³ and R ⁴
May be the same or different. Also,
R ² , R ⁵ and R ⁶ are each an alkylene group having 2 to 4 carbon atoms, and R ⁵ and R ⁶ may be the same or different. m is an integer of 1 to 10, and n is an integer of 0 to 10.

In the present invention, as the component (A), a mono-form represented by the general formula [I] or a bis-form represented by the general formula [II] may be used. These mixtures may be used. The polyalkenyl or polyalkyl succinimide represented by the general formulas [I] and [II] is usually a polyalkenyl succinic anhydride obtained by a reaction between polyolefin and maleic anhydride, or a polyalkyl succinic hydride thereof. Acid anhydrides can be prepared by reacting with a polyalkylene polyamine. The mono- and bis-forms of the polyalkenyl or polyalkylsuccinimide can be produced by changing the reaction ratio between the polyalkenyl or polyalkylsuccinic anhydride and the polyalkylenepolyamine.

In the production of polyalkenyl or polyalkylsuccinimide, the polyolefin used as a raw material is appropriately selected from those obtained by polymerizing α-olefin having about 2 to 8 carbon atoms and used. . The α-olefin forming the polyolefin may be used alone or in combination of two or more. Polybutene is particularly preferred as the polyolefin. On the other hand, examples of the polyalkylene polyamine include polyethylene polyamine, polypropylene polyamine, and polybutylene polyamine. Of these, polyethylene polyamine is preferable.

In the lubricating oil composition for an internal combustion engine of the present invention, the succinimide used as the component (A) must have a weight average molecular weight of 2500 or more. By setting the weight average molecular weight to 2500 or more, solid impurities such as soot in the oil can be dispersed in the oil, and the viscosity of the lubricating oil does not increase rapidly. When the weight average molecular weight is less than 2500, solid impurities such as soot in the oil are aggregated and coarsened, and as a result, the viscosity of the lubricating oil rapidly increases, and the intended effect is not sufficiently exhibited. In particular, when the weight average molecular weight is 2,000 or less, solid impurities are aggregated and coarsened. In addition,
The value of the weight average molecular weight is a value converted into polybutene by GPC (gel permeation chromatography).

In the lubricating oil composition for an internal combustion engine of the present invention, the amount of succinimide used as the component (A) is 0.03 to 3.0% as nitrogen (N) derived from succinimide based on the total amount of the composition. Although it is necessary to be blended in the range of 0.12% by weight, the amount of nitrogen is 0.05 to 0.12% by weight
Is particularly preferably used, and particularly preferably, the amount of nitrogen is in the range of 0.06 to 0.12% by weight. If the amount is less than 0.03% by weight of nitrogen, the desired effect is not sufficiently exhibited, while the amount of component (A) exceeds 0.12% by weight of nitrogen. However, improvement in dispersibility by increasing the blending amount cannot be obtained.

(3) Metal Detergent In the lubricating oil composition for an internal combustion engine of the present invention, a metal detergent is used as an essential component (B). As the metal detergent, a basic alkaline earth metal sulfonate or one of the basic alkaline earth metal sulfonate and the basic alkaline earth metal salicylate or phenate is blended.

The basic alkaline earth metal sulfonate is
It is an alkaline earth metal salt of a hydrocarbon group-containing sulfonic acid such as petroleum sulfonic acid or sulfonic acid of long-chain alkylbenzene or alkylnaphthalene, and is a basic salt. As the alkaline earth metal, calcium, magnesium, and barium are used, and among them, calcium is preferable. The total base number of the alkaline earth metal sulfonate is 200-4.
50 mgKOH / g, preferably 200-400
mg KOH / g. Total base number is 200mgKOH /
If the amount is less than g, the ability to neutralize the acidic substance generated by the deterioration becomes small, so that sufficient acid neutralization performance cannot be obtained and the life cannot be extended. In addition, the soot dispersion performance deteriorates, and the viscosity increase due to soot increases. On the other hand, if it exceeds 450 mgKOH / g, calcium carbonate in the metal detergent tends to precipitate, and no improvement in the acid neutralizing ability is recognized for its total base number. The total base number is based on JIS K2
It is a value measured by the 501 perchloric acid method.

The basic alkaline earth metal salicylate is
It is obtained by converting an alkaline earth metal salt of salicylic acid into a basic salt with calcium carbonate. As alkaline earth metals,
Calcium, magnesium, and barium are used,
Among them, calcium is preferred. The total base number of the alkaline earth metal salicylate is 100 to 350 mgKOH / g, preferably 200 to 300 mgKOH / g. When the total base number is less than 100 mgKOH / g, the ability to neutralize acidic substances generated by deterioration is reduced,
Sufficient acid neutralization performance cannot be obtained, and a longer life cannot be achieved.
On the other hand, if it exceeds 350 mgKOH / g, calcium carbonate in the metal detergent tends to precipitate, and no improvement in the acid neutralizing ability is recognized for its total base number. The method for producing the basic alkaline earth metal salicylate is arbitrary, and can be produced by a known method. Also, commercially available products can be used for the component (B) of the present invention. Examples of commercially available products of this kind include SAP005 (manufactured by Infinium Japan) having a total base number of 280 mgKOH / g, and SAP001 (manufactured by Infinium Japan) having a total base number of 168 mgKOH / g. Can be.

The basic alkaline earth metal phenate is an alkaline earth metal salt of an alkylphenol or a sulfurized alkylphenol, and is a basic salt. As the alkaline earth metal, calcium, magnesium, and barium are used, and among them, calcium is preferable. The total base number of the alkaline earth metal phenate is 100-350 mgK
OH / g, preferably 200-300 mg KOH
/ G. If the total base number is less than 100 mgKOH / g, the ability to neutralize the acidic substance generated by the deterioration becomes small, so that sufficient acid neutralization performance cannot be obtained, and the life cannot be extended. On the other hand, if it exceeds 350 mgKOH / g, calcium carbonate in the metal detergent tends to precipitate,
No improvement in the acid neutralizing ability is recognized for the total base number.

In the lubricating oil composition of the present invention, a metal detergent which is an essential component (B), that is, a basic alkaline earth metal sulfonate, or the basic alkaline earth metal sulfonate and the basic alkaline earth metal salicylate Alternatively, the compounding amount of either phenate is such that the total base number derived from the metal detergent is 6 to 18 mg KO with respect to the total amount of the composition.
The amount is in the range of H / g. When the compounding amount of the metal detergent, that is, the amount in which the total base number derived from the metal detergent is less than 6 mgKOH / g, solid impurities such as soot in the oil cannot be dispersed in the oil, and Agglomeration and coarsening occur, and as a result, the viscosity of the lubricating oil sharply increases, and the intended effect is not sufficiently exhibited. On the other hand, when the total base number derived from the metal detergent is more than 18 mgKOH / g, the ability to disperse solid impurities such as soot in oil in oil due to an increase in the blending amount is not recognized. Deposits may increase due to deterioration of the metal detergent itself.

A basic alkaline earth metal sulfonate;
Even in the case of using a mixture with a basic alkaline earth metal salicylate or a basic alkaline earth metal phenate, the compounding amount thereof is such that the total base number derived from the metal detergent is 6 to 18 mgKOH / g with respect to the total amount of the composition. However, the mixing ratio of the basic alkaline earth metal salicylate or the basic alkaline earth metal phenate with respect to the entire metal detergent, based on the total base number, in the case of the salicylate,
The amount is at most 40%, preferably 25 to 3%.
7.5%, and with the phenate,
The amount is at most 20%, preferably 0.5 to 6%. The mixing ratio of the basic alkaline earth metal salicylate or basic alkaline earth metal phenate to the entire metal detergent is 40% based on the total base number.
If the amount exceeds 20% or exceeds 20%, solid impurities such as soot in the oil cannot be sufficiently dispersed in the oil, and the solid impurities aggregate and coarsen. As a result, the viscosity of the lubricating oil is increased. And the expected effect is not fully exhibited.

(4) Zinc dialkyldithiophosphate In the lubricating oil composition for an internal combustion engine of the present invention, zinc dialkyldithiophosphate is used as an essential component (C), an antiwear agent or an antioxidant. Zinc dialkyldithiophosphate is represented, for example, by the following general formula [III].

[0024]

Embedded image

In the above general formula [III], R ⁷ is
A primary (primary) or secondary (secondary) alkyl group having 1 to 26 carbon atoms, which may be the same or different from each other. R ⁷ is preferably an alkyl group having 3 to 12 carbon atoms, and particularly preferably a secondary (secondary) alkyl group.

In the lubricating oil composition for an internal combustion engine of the present invention, the compounding amount of the zinc dialkyldithiophosphate, which is an essential component (C), is 0. 04 to 0.50% by weight. If the amount of phosphorus derived from zinc dithiophosphate in the entire composition is less than 0.04% by weight, satisfactory antiwear properties may not be obtained under high-temperature and low-speed operation conditions. On the other hand, if the amount of phosphorus derived from zinc dithiophosphate exceeds 0.50% by weight in the entire composition, no improvement in the wear prevention effect due to an increase in the amount of the compound is not observed.

(5) Other Additive Components The lubricating oil composition for an internal combustion engine of the present invention contains the above-mentioned components (A), (B) and (B) as essential components in a lubricating base oil composed of mineral oil and / or synthetic oil. The compound of (C) is blended, and if necessary, other additive components conventionally used in lubricating oils for internal combustion engines, for example, viscosity index improvers,
Pour point depressants, antioxidants, friction reducers, antiwear agents, extreme pressure agents, metal deactivators, rust inhibitors, defoamers, corrosion inhibitors,
A coloring agent or the like can be appropriately added as long as the object of the present invention is not impaired.

Examples of the viscosity index improver include polymethacrylates, olefin copolymers (polyisobutylene, ethylene-propylene copolymers), polyalkylstyrenes, styrene-butadiene hydrogenated copolymers, and styrene-maleic anhydride. Examples thereof include acid ester copolymers, which are usually used in a proportion of 1 to 30% by weight.

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

Examples of the antioxidant include, in addition to the above-mentioned essential component (C) zinc dialkyldithiophosphate, amine antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated phenyl-α-naphthylamine. Phenolic antioxidants such as 2,6-di-tert-butylphenol and 4,4'-methylenebis- (2,6-di-tert-butylphenol);
Examples include sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate and phosphorus-based antioxidants such as phosphite. Among them, amine-based antioxidants and phenol-based antioxidants are preferably used. . These are usually 0.
It is used in a proportion of from 0.5 to 5% by weight.

Examples of the friction reducing agent include organic molybdenum compounds, fatty acids, higher alcohols, fatty acid esters, oils and fats, amines, amides, sulfide esters, phosphate esters, phosphite esters, phosphate ester amine salts and the like. Can be These are usually used at a ratio of 0.05 to 3% by weight.

Examples of the antiwear agent include metal dithiophosphate (Pb, Sb, Mo, etc.) and metal dithiocarbamate (Zn, Pb, Sb, etc.) in addition to the above-mentioned essential component (C) zinc dialkyldithiophosphate. Mo), metal salts of naphthenic acids (such as Pb), metal salts of fatty acids (such as Pb),
Examples include a boron compound, a phosphoric ester, a phosphite, a phosphoric ester amine salt and the like. These are usually used at a ratio of 0.1 to 5% by weight.

The extreme pressure agent includes, for example, ashless sulfide compounds, sulfurized oils and fats, phosphate esters, phosphite esters, phosphate ester amine salts and the like. These are usually 0.05 to 3% by weight. Used in proportions.

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

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

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

[0037]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not particularly limited to these examples. The methods of measuring and evaluating the lubricating oil viscosity increase rate and soot average particle diameter in oil in soot mixing in Examples and Comparative Examples were carried out by the following methods.

(1) Method of Measuring and Estimating Lubricant Viscosity Increase Rate and Soot Average Particle Size in Oil When Soot is Mixed In advance, the actual diesel engine is operated only with the lubricating oil base oil, and concentrated soot is used as the lubricating oil. A lubricating oil composition is prepared by blending in a predetermined amount, and the kinematic viscosity of the lubricating oil before soot blending and one day after soot blending is measured in accordance with JIS K2283,
The lubricating oil viscosity increase rate when soot is mixed is calculated from the kinematic viscosity before and after soot mixing. Further, the average particle size of soot in the lubricating oil after one day of soot blending is measured by a light scattering method. If the rate of increase in the viscosity of the lubricating oil increases, it is determined that the soot in the oil is agglomerated due to agglomeration.Here, solid impurities such as soot in the oil are sufficiently dispersed in the oil. 1 that is judged to be
The development target was a lubricating oil viscosity increase rate of less than 50% at 00 ° C.

(2) Preparation and Evaluation of Lubricating Oil Composition (Examples and Comparative Examples) [Example 1] As a lubricating base oil, a solvent-refined paraffinic mineral oil (viscosity at 100 ° C of 5.6 mm ² / s) was used. A succinimide having a weight average molecular weight of 2550 was used as the component (A) in an amount of 0.06% by weight as the amount of nitrogen (N), and the total base was used as the component (B). Calcium sulfonate having a TBN value of 250 mgKOH / g as a TBN amount;
The amount corresponding to 1 mg KOH / g and the total base number (TBN)
A basic calcium salicylate having a TBN amount of 4.9 mgKOH / g, that is, a TBN amount of 16.0 mgKOH / g in the lubricating oil derived from the metal detergent of the component (B); T from basic calcium salicylate to total metal detergent
An amount corresponding to a BN ratio of 30.6%, zinc dialkyldithiophosphate as a component (C) 0.14% by weight as a phosphorus (P) component, and a viscosity index improver as another additive component , Pour point depressant and defoamer in total of 3.92
A lubricating oil composition containing 4.0% by weight of soot was further prepared from the lubricating oil composition containing 4.0% by weight of soot, and the viscosity increase rate of the lubricating oil when soot was mixed and the average particle size of soot in oil were measured. Table 1 shows the results. The lubricating oil viscosity increase rate does not increase so much (10
(34.7% at 0 ° C.), and the average particle size of soot in oil is 122.
nm and is not coarse, and solid impurities such as soot in the oil are sufficiently dispersed in the lubricating oil.

Example 2 Example 1 was used as a lubricating base oil.
In the same manner as in Example 1, a solvent-refined paraffinic mineral oil (having a viscosity of 5.6 mm ² / s at 100 ° C.) was used, and based on the total amount of the composition, as the component (A), the weight average molecular weight was as in Example 1. The succinimide of 2550 is converted to nitrogen (N)
0.06% by weight of a basic calcium sulfonate having a total base number (TBN) of 250 mgKOH / g as the component (B) of 14.8 mgK
OH / g and a total base number (TBN) of 250
an amount corresponding to 1.2 mg KOH / g as a basic calcium salicylate of mg KOH / g as a TBN amount;
That is, TB in lubricating oil derived from the metal detergent of component (B)
N is 16.0 mgKOH / g, and the amount of the basic calcium salicylate-derived TBN to the entire metal detergent is 7.5%, and as the component (C), the dialkyldithioline is used in the same manner as in Example 1. 0.14% by weight of zinc acid in terms of phosphorus (P) and, similarly to Example 1, a total of 3.92 of a viscosity index improver, a pour point depressant, and a defoamer as other additive components. A lubricating oil composition containing 4.0% by weight of soot was further prepared from the lubricating oil composition containing 4.0% by weight of soot, and the viscosity increase rate of the lubricating oil when soot was mixed and the average particle size of soot in oil were measured. Table 1 shows the results. The lubricating oil viscosity increase rate did not increase so much (36.6 at 100 ° C.).
%), And the average particle size of soot in oil is 120 nm. As in Example 1, the soot is not coarsened and solid impurities such as soot in oil are sufficiently dispersed in lubricating oil.

[Examples 3 and 4] As lubricating base oils, solvent-refined paraffinic mineral oils (100
5.6 mm ² / s), and succinimide having a weight-average molecular weight of 2550 was replaced with nitrogen (as component (A)) in the same manner as in Examples 1 and 2, based on the total amount of the composition. 0.06% by weight as an amount of N), and as a component (B), a basic calcium sulfonate having a total base number (TBN) of 250 mgKOH / g as a TBN amount;
In Example 3, 15.2 mgKOH / g, and in Example 4, 1 mgKOH / g
The amount corresponding to 2.9 mg KOH / g and the total base number (TB
N) is 250 mgKOH / g and the basic calcium phenate is defined as the amount of TBN.
OH / g, an amount corresponding to 3.1 mg KOH / g in Example 4, that is, the TBN in the lubricating oil derived from the metal detergent of the component (B) was 16.0 mg KOH / g, and the base relative to the entire metal detergent. TB derived from soluble calcium phenate
The ratio of N is 5.0% in the third embodiment and 1% in the fourth embodiment.
In the same manner as in Examples 1 and 2, the amount corresponding to 9.4% and 0.14% by weight of zinc dialkyldithiophosphate as the amount of phosphorus (P) as the component (C), and in Example 1,
Similar to 2, a lubricating oil composition containing a total of 3.92% by weight of a viscosity index improver, a pour point depressant, and a defoamer as other additive components, and further 4.0% by weight of soot is added. The oil composition was prepared, and the lubricating oil viscosity increase rate when soot was mixed and the average particle size of soot in oil were measured. Table 1 shows the results. The lubricating oil viscosity increase rate did not increase so much (35.6% in Example 3 at 100 ° C., 39.0 in Example 4), and the average soot particle diameter in oil was 148 nm in Example 3. In Example 4, the thickness was 132 nm, and as in Examples 1 and 2, solid impurities such as soot in the oil were not dispersed and sufficiently dispersed in the lubricating oil.

[Examples 5 and 6] As lubricating base oils, solvent-refined paraffinic mineral oils (100
5.6 mm < ² > / s), and based on the total amount of the composition, succinimide having a weight average molecular weight of 2550 was replaced with nitrogen (A) as in the case of Examples 1-4. The amount of N) is 0.06% by weight, and the total base number (TBN) is 250 mg in Example 5 as the component (B).
16. A basic calcium sulfonate of KOH / g, 220 mg KOH / g in Example 6, was used as a TBN amount.
An amount corresponding to 0 mg KOH / g, and as the component (C),
As in Examples 1 to 4, zinc dialkyldithiophosphate was added in an amount of 0.14% by weight of phosphorus (P), and as in Examples 1 to 4, a viscosity index improver was used as another additive component, A lubricating oil composition containing a total of 3.92% by weight of a pour point depressant and a defoamer was further mixed with 4.0% by weight of soot to prepare a lubricating oil composition. The average particle size of soot in oil was measured. The results are also shown in Table 1. The lubricating oil viscosity increase rate does not increase so much (45.4% in Example 5 at 100 ° C., 48.5% in Example 6),
The average soot particle diameter in oil was 164 nm in Example 5 and 166 nm in Example 6, and was similar to Examples 1 to 4.
It is not so coarse, and solid impurities such as soot in oil are sufficiently dispersed in lubricating oil.

[0043]

[Table 1]

Comparative Examples 1 to 9 In the same manner as in Examples 1 to 6, lubricating base oil components and various additive components shown in Table 2 were blended in the proportions shown in the same table, and soot was further added to 4.0. By weight, a lubricating oil composition was prepared, and the rate of increase in the viscosity of the lubricating oil when soot was mixed and the average particle size of soot in oil were measured. Table 2 shows these results.
Shown in The rate of increase in the viscosity of the lubricating oil is increasing, and the average particle size of soot in oil is larger than in Examples 1 to 6, and the particle size of soot is coarse.

[0045]

[Table 2]

From the above Examples and Comparative Examples, the lubricating base oil was added to the lubricating base oil according to the present invention: (A) a succinimide having a weight average molecular weight of a specific amount or more, and (B) a total base number in a specific range. A specific amount of a basic alkaline earth metal sulfonate, or a metal detergent obtained by combining a basic alkaline earth metal sulfonate with a basic alkaline earth metal salicylate or phenate, and (C) zinc dialkyldithiophosphate. Thus, in any of the examples, it is apparent that the insoluble solid impurities (soot) in the oil are finely dispersed, and the oil has an excellent effect of not coarsening and not rapidly increasing the viscosity of the lubricating oil. became. That is, taking the result of Example 1 as an example, the soot average particle diameter is 1
It is 22 nm, and the viscosity increase rate of the lubricating oil is 34.7% at 100 ° C., which is not so much increased, and it is apparent that the life can be extended. Similarly, Examples 2 to
As for No. 6, an insoluble solid impurity (soot) is finely dispersed in the oil to obtain an excellent effect that the oil does not coarsen and the viscosity of the lubricating oil does not increase rapidly.

On the other hand, in Comparative Example 1, in place of (B) a basic calcium sulfonate having a total base number in a specific range, which is one of the essential components of the present invention, a basic calcium sulfonate having a total base number out of the specific range was used. Are prepared and evaluated, but the average particle size of soot in the oil is coarsened and the viscosity of the lubricating oil is rapidly increasing, which does not satisfy the development target. In Comparative Example 2, succinimide having a weight average molecular weight of less than a specific amount was blended in place of (A) succinimide having a weight average molecular weight of a specific amount or more, which is one of the essential components of the present invention. A lubricating oil composition for an internal combustion engine has been prepared and evaluated, but the average particle size of soot in the oil has been coarsened and the viscosity of the lubricating oil has rapidly increased, which does not satisfy the development target. Similarly, in Comparative Examples 3 and 4, basic calcium phenate or basic calcium salicylate is blended in place of (B) basic calcium sulfonate which is an essential component of the present invention. The average particle size of soot in oil has become coarse, and the viscosity of lubricating oil has increased sharply, failing to meet the development goals. In Comparative Examples 5 to 9, (B) a basic alkaline earth metal sulfonate, which is an essential component of the present invention, and either a basic alkaline earth metal salicylate or a phenate are blended. In any case, Comparative Examples 1 to 4 because the mixing ratio with salicylate or phenate is not in the specific range.
Similarly, the average particle size of soot in oil is coarsened, and the viscosity of lubricating oil is rapidly increasing, which does not satisfy the development target.

From these, the lubricating base oil is added to the essential components of the present invention (A) succinimide having a weight average molecular weight of a specific amount or more, and (B) basic alkaline earth having a total base number in a specific range. A metal detergent comprising a similar metal sulfonate, or the basic alkaline earth metal sulfonate and either a basic alkaline earth metal salicylate or a phenate having a total base number in a specific range, and (C) zinc dialkyldithiophosphate; Unless each is blended in a specific amount, solid impurities (soot) insoluble in the oil are not finely dispersed, but aggregate and coarse. As a result, it is clear that the viscosity of the lubricating oil sharply increases, and high-quality lubricating oil for an internal combustion engine cannot be obtained. That is, (A) a succinimide having a weight average molecular weight of not less than a specific amount,
A basic alkaline earth metal sulfonate having a total base number in a specific range, or a metal detergent comprising the basic alkaline earth metal sulfonate and any one of a basic alkaline earth metal salicylate or a phenate having a total base number in a specific range. By mixing a specific amount of the agent and (C) zinc dialkyldithiophosphate, the solid impurities (soot) insoluble in the oil are finely dispersed and are not coarsened.
Demonstrates the excellent effect that the viscosity of the lubricating oil does not increase rapidly,
It has been found that a long-life lubricating oil composition for an internal combustion engine can be obtained.

[0049]

According to the lubricating oil composition for an internal combustion engine of the present invention, (A) a succinimide having a weight average molecular weight of a specific amount or more and (B) a total base number in a specific range are added to a lubricating base oil. (C) a basic alkaline earth metal sulfonate, or a metal detergent comprising the basic alkaline earth metal sulfonate and one of a basic alkaline earth metal salicylate or a phenate having a total base number in a specific range; By mixing zinc dialkyldithiophosphate in a specific amount, the insoluble solid impurities (soot) in the oil are finely dispersed to prevent coarsening and an excellent effect that the viscosity of the lubricating oil does not sharply increase. Demonstrates excellent long-life performance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 137/10 C10M 137/10 // C10N 10:04 C10N 10:04 30:02 30:02 40:25 40:25 (72) Inventor Satoshi Ogano 1-3-1 Nishitsurugaoka, Oi-machi, Iruma-gun, Saitama F-term in Tonen Research Laboratory (reference) 4H104 BF03C BH07C DA02A DB06C DB07C EA03C EA22C EB02 FA02 LA02 PA41

Claims (2)

[Claims] 1. A lubricating base oil composed of a mineral oil and / or a synthetic oil, having (A) a weight average molecular weight of 25 based on the total amount of the composition.
Succinimide which is not less than 00 is 0.0
3 to 0.12% by weight, and (B) a basic alkaline earth metal sulfonate having a total base number of 200 to 450 mg KOH / g as a metal detergent, and a total base number derived from the metal detergent of 6 to 18 mg KOH / g. g, and (C) a zinc dialkyldithiophosphate in an amount of 0.04 to 0.5% by weight in terms of phosphorus, and a lubricating oil composition for an internal combustion engine. 2. The metal detergent further includes a basic alkaline earth metal salicylate or phenate having a total base number of 100 to 350 mg KOH / g, wherein the salicylate or the phenate in the entire metal detergent is based on the total base number. 2. The lubricating oil composition for an internal combustion engine according to claim 1, wherein the lubricating oil composition is blended in a proportion of at most 40% or 20%.