JP2012057166A - Lubricant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition having low contents in all of sulfate ash, phosphorus, sulfur and chlorine, and suitable for lubrication of the engine of diesel engine-mounted vehicles particularly using a low-sulfur hydrocarbon-based fuel as a traveling fuel.SOLUTION: The lubricant composition comprises dissolving or dispersing the following components (a) to (d) into a low-sulfur base oil, and has low contents in all of sulfate ash, phosphorus, sulfur and chlorine: (a) an ashless dispersant which is an alkenyl- or alkyl-succinic imide or a derivative thereof; (b) a cleaning agent being a low-sulfur calcium alkylsalicylate (provided that 0.2-7 mass% of organic acid metal salts contained in the cleaning agent exists in the composition, and the cleaning agent is a mixture of a cleaning agent comprising unsulfurized calcium alkylsalicylates having 14-18C alkyl and that having 20-28C alkyl); (c) a nonabrasive agent comprising zinc phosphate; and (d) an antioxidant.

Description

  The present invention relates to a lubricating oil composition useful for lubricating internal combustion engines used on land such as diesel engines, gasoline engines, and gas engines. More specifically, the present invention has a low ash content, a low phosphorus content, and a low sulfur content, and is excellent in high temperature cleanliness and wear resistance. Also, the particulate filter, unburned soot and fuel in the exhaust gas are used. For internal combustion engines that have less adverse effects on exhaust gas purification devices such as oxidation catalysts mounted on automobiles to oxidize oil and lubricating oil, and can fully meet recent strict exhaust gas regulations and stricter exhaust gas regulations expected in the future The present invention relates to a lubricating oil composition. In particular, the present invention relates to an automobile, particularly an exhaust gas purifier (particularly a particulate), using a hydrocarbon fuel having a sulfur content of about 0.005 mass% or less (particularly about 0.001 mass% or less) as a running fuel. Provided is an environment-friendly lubricating oil composition for an internal combustion engine that is suitably used in a diesel engine vehicle equipped with a filter and an oxidation catalyst.

Internal combustion engine, a vehicle having a diesel engine in particular land travel, measures against environmental pollution caused by exhaust gas components such as particulate and NO _X is an important issue.
As countermeasures, there are exhaust gas purification devices such as particulate filters and oxidation catalysts in automobiles, but when using conventional lubricating oil for internal combustion engines with high ash content, phosphorus content and sulfur content, the particulate filter The soot adhering to is removed by oxidation and combustion in the exhaust gas purification apparatus, but the problem of filter clogging due to metal oxides, sulfates, carboxylates, etc. generated by combustion cannot be solved.

  Furthermore, the presence of sulfur in the fuel leads to the incorporation of sulfuric acid or sulfate into the exhaust gas, so it is necessary to reduce the sulfur content as much as possible, especially considering the adverse effect on the oxidation catalyst, and fuel sulfur reduction is further advanced. It is out. Taking diesel oil for automobiles equipped with diesel engines as an example, the sulfur content is reduced from about 0.005 mass% or less to about 0.001 mass% or less. If the fuel is reduced in sulfur, the amount of metal-based detergent (metal-containing detergent) added to the lubricating oil required to neutralize sulfuric acid or the like can be reduced. A part of the lubricating oil is used for lubrication in the engine, and at the same time, it is burned and discharged as a part of the exhaust gas. Therefore, it is natural that the metal content and sulfur content in the lubricating oil are preferably as low as possible. Furthermore, it is preferable to reduce the phosphorus content in the lubricating oil in order to prevent deterioration of the catalyst. In addition, if chlorine is mixed into the exhaust gas, dioxins are likely to be generated, so it is preferable that the amount of chlorine in the lubricating oil is small.

  That is, conventionally, diesel engines used on land such as automobiles, construction machines, and generators are operated using fuel (light oil or heavy oil) having a sulfur content of about 0.005% by mass or more as described above. In general, as a diesel engine lubricating oil, about 1.3 to 2% by mass of sulfated ash, about 0.3 to 0.7% by mass of sulfur, and about 0.1 to 0 of phosphorus are conventionally used. .13% by weight has been used in many cases.

On the other hand, as a lubricating oil that responds to the demands of low ash content, low phosphorus content, low sulfur content, and low chlorine content in recent lubricating oils, Patent Document 1 discloses a low sulfur content as described above. A lubricating oil composition suitable for lubricating a diesel engine using fuel is described, and the lubricating oil composition is a base oil having a sulfur content of 0.1% by mass or less (preferably 0.03% by mass or less). At least based on the total mass of the composition,
a) An ashless dispersant that is an alkenyl or alkyl succinimide or a derivative thereof is 0.01 to 0.3% by mass in terms of nitrogen content,
b) A metal-containing detergent (so-called metal detergent) having a sulfur content of 3% by mass or less and a total base number of 10 to 350 mgKOH / g is 0.1 to 1% by mass in terms of sulfated ash.
c) zinc dialkyldithiophosphate is 0.01 to 0.12% by weight in terms of phosphorus content, and d) 0.01 to 5% by mass of an antioxidant phenol compound and / or an antioxidant amine compound. ,
The amount of sulfated ash is in the range of 0.1 to 1% by weight, the phosphorus content is in the range of 0.01 to 0.1% by weight, based on the total weight of the composition, and The sulfur content is in the range of 0.01 to 0.3% by mass, the chlorine content is 40 ppm or less, and the organic acid metal salt contained in the metal-containing detergent is 0.2 to 7 in the composition. It is characterized by the presence of mass% (preferably 0.5-5 mass%, more preferably 1.0-3 mass%).

  In addition, as a preferable example of the metal-containing detergent of the component a), [0022] of Patent Document 1 includes an alkali metal salt or alkaline earth of a non-sulfurized alkyl salicylate having an average number of carbon atoms of about 8 to 30. Metal salts are described.

JP 2002-53888 A

  Recently (2008), “Automobile Diesel Engine Lubricant (JASO M 355: 2008)” established by the Society of Automotive Engineers of Japan, covers trucks and buses equipped with aftertreatment devices to comply with exhaust gas regulations. The lubricating oil according to DH-2-08 has a sulfate ash content of 1.0 ± 0.1%, a phosphorus content of 0.12% by mass or less, a sulfur content of 0.5% by mass or less, and a chlorine content The amount is specified to be 150 ppm or less.

  The present invention satisfies the above (JASO M 355: 2008) regulations and has a high high temperature cleanliness particularly at a temperature of 300 ° C. or higher compared to the lubricating oil composition described in Patent Document 1. It is an object of the present invention to provide a lubricating oil composition for an internal combustion engine that can sufficiently cope with severe operating conditions such as higher temperatures in the engine in recent years and predicted in the future.

  The inventor of the present invention has studied to further improve the cleanliness at high temperature realized by the lubricating oil composition described in Patent Document 1. As a result, as an alkali metal salt or alkaline earth metal salt of a non-sulfurized alkyl salicylate having an average carbon atom number of about 8 to 30 described as a preferred example of the metal-containing detergent in Patent Document 1, the number of carbon atoms is Alkyl salicylic acid calcium salt which is a mixture of a non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group in the range of 14 to 18 and a non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group in the range of 20 to 28 carbon atoms By using in combination with a cleaning agent, especially at a high temperature of 300 ° C. or higher, the cleanliness is improved, the wear resistance is also high, and the low-temperature viscosity is advantageous for use in cold regions. The inventors have found that an oil composition can be obtained and have reached the present invention.

Accordingly, in the present invention, at least the following components a) to d) are dissolved or dispersed in a base oil having a sulfur content of 0.1% by mass or less (preferably 0.03% by mass or less). The amount is in the range of 0.1 to 1.1% by mass, the phosphorus content is in the range of 0.01 to 0.12% by mass, the sulfur content is in the range of 0.01 to 0.5% by mass, and the chlorine content is Is below 150 ppm,
A lubricating oil composition for lubricating an internal combustion engine operated using a fuel oil having a sulfur content of 0.005 mass% or less (particularly 0.001 mass% or less).
a) An ashless dispersant that is an alkenyl or alkyl succinimide or a derivative thereof is 0.01 to 0.3% by mass in terms of nitrogen content,
b) An alkyl salicylic acid calcium salt detergent having a sulfur content of 3% by mass or less and a total base number of 10 to 350 mg KOH / g is 0.1 to 1% by mass in terms of sulfated ash, provided that the alkyl salicylic acid calcium salt is purified. The organic acid metal salt contained in the agent is present in the composition in an amount of 0.2 to 7% by mass (preferably 0.5 to 5% by mass, more preferably 1.0 to 3% by mass), and the calcium alkylsalicylate Non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms and non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 20 to 28 carbon atoms Is a mixture with,
c) a zinc phosphate antiwear agent selected from the group consisting of zinc dialkyldithiophosphate and zinc dihydrocarbyl phosphate is 0.01 to 0.12% by mass in terms of phosphorus content, and d) antioxidant phenol 0.01 to 5% by mass of an antioxidant selected from the group consisting of a compound and an antioxidant amine compound,
However, the above-mentioned sulfated ash content, phosphorus content, sulfur content, and mass% of components a) to d) are values based on the total mass of the composition.

Preferred embodiments of the lubricating oil composition of the present invention are described below.
(1) The total base value of the alkyl salicylic acid calcium salt detergent of component b) is in the range of 30 to 300 mg KOH / g.
(2) The total base number of the non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms is in the range of 100 to 250 mg KOH / g.
(3) The total base number of the non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 20 to 28 carbon atoms is in the range of 280 to 350 mgKOH / g.
(4) The alkylsalicylic acid calcium salt detergent is a non-sulfurized alkylsalicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms and a non-sulfurizing alkylsalicylic acid calcium salt detergent having an alkyl group having 20 to 28 carbon atoms. It is a mixture of 2: 8 to 8: 2 (particularly, 3: 7 to 7: 3) in terms of the calcium amount ratio (amount ratio of calcium contained in each detergent) with the sulfurized alkylsalicylic acid calcium salt detergent.
(5) The calcium alkylsalicylate detergent is a non-sulfurized alkylsalicylate calcium detergent having an alkyl group having 14 to 18 carbon atoms and a non-sulfurizing alkyl salicylate having an alkyl group having 20 to 28 carbon atoms. 4: 6 to 8: 2 (especially 5: 5 to 7: 3) in terms of the amount ratio of organic acid metal salt to the sulfurized alkylsalicylic acid calcium salt detergent (quantity ratio of organic acid metal salt contained in each detergent) ).
(6) The ashless dispersant of component a) reacts polybutenyl succinic anhydride obtained by a thermal reaction method using polybutene and maleic anhydride as raw materials without contacting chlorine or a chlorine-containing compound with polyamine. Succinimide or a derivative thereof. (7) Furthermore, a molybdenum containing compound is contained 0.01-5 mass%.
(8) The total base number is in the range of 1 to 17 mg KOH / g (particularly in the range of 2 to 13 mg KOH / g).
(9) The lubricating oil composition is a 0W5, 0W10, 0W15, 0W20, 0W30, 5W20, 5W30, 10W20, or 10W30 multigrade engine oil containing a viscosity index improver.
(10) For lubrication of a diesel engine mounted on a vehicle for land travel that is operated using a fuel oil having a sulfur content of 0.005 mass% or less (particularly 0.001 mass% or less).

  The present invention also uses a lubricating oil composition of the present invention as described above, and is a vehicle for land travel that is driven using a fuel oil having a sulfur content of 0.005 mass% or less (particularly 0.001 mass% or less). There is also a method of operating the diesel engine installed in the vehicle.

  The lubricating oil composition of the present invention, like the lubricating oil composition described in Patent Document 1, has a severe operation of 300 ° C. or higher despite having a low sulfated ash content, a low phosphorus content, and a low sulfur content. It exhibits high cleanliness even under conditions, has a high level of wear resistance, and has a low low-temperature viscosity that is advantageous for use in cold regions. Therefore, the lubricating oil composition of the present invention uses a hydrocarbon-based fuel having a sulfur content of about 0.005% by mass or less (particularly about 0.001% by mass or less) as a running fuel. In particular, it is suitably used for lubrication of a diesel engine equipped with a diesel engine equipped with a particulate filter and an oxidation catalyst.

As the base oil in the lubricating oil composition of the present invention, mineral oil or synthetic oil having a kinematic viscosity at 100 ° C. of ² to 50 mm ² / s is usually used. Although there is no restriction | limiting in particular about the kind of this mineral oil or synthetic oil, or other properties, As a base oil, sulfur content needs to be 0.1 mass% or less. The sulfur content is desirably 0.03% by mass or less, and particularly desirably 0.005% by mass or less.

The mineral oil base oil is preferably obtained by treating a mineral oil base oil fraction using a combination of solvent refining or hydrotreating treatment methods as appropriate, particularly highly hydrorefined base oils (for example, viscosity A base oil having an index of 100 to 150, an aromatic content of 5% by mass or less, and nitrogen and sulfur contents of 50 ppm or less is preferably used.
Among them, a high viscosity index base oil (for example, viscosity index 140-160) obtained by hydroisomerizing slack wax or GTL wax is particularly preferably used.

  Synthetic oils (synthetic lubricating base oils) include, for example, poly-α-olefins, which are polymers of α-olefins having 3 to 12 carbon atoms, sebacic acid, azelaic acid, adipic acid represented by dioctyl sebacate, etc. Dialkyl diester which is an ester of a dibasic acid and an alcohol having 4 to 18 carbon atoms, polyol ester which is an ester of 1-trimethylolpropane or pentaerythritol and a monobasic acid having 3 to 18 carbon atoms, 9 to 40 carbon atoms And alkylbenzene having an alkyl group of In general, synthetic oils are substantially free of sulfur, are excellent in oxidation stability and heat resistance, and are less likely to form residual carbon and soot once burned, so that they can be preferably used in the lubricating oil composition of the present invention.

  Mineral base oils and synthetic base oils can be used alone, but if desired, two or more mineral base oils or a combination of two or more synthetic base oils may be used. it can. Further, if desired, a mineral base oil and a synthetic base oil can be used in combination at any ratio.

  As the ashless dispersant as component a) in the lubricating oil composition of the present invention, an alkenyl or alkyl succinimide derived from polyolefin or a derivative thereof is used. The addition amount is in a range of 0.01 to 0.3% by mass in terms of nitrogen content based on the total mass of the composition. Exemplary succinimides include succinic anhydrides substituted with high molecular weight alkenyl or alkyl groups and polyalkylene polyamines containing an average of 4 to 10 (preferably 5 to 7) nitrogen atoms per molecule. It can obtain by reaction of. The high molecular weight alkenyl or alkyl group is preferably a polybutene having a number average molecular weight of about 900 to 3,000.

In the process of obtaining polybutenyl succinic anhydride by reaction of polybutene and maleic anhydride, a chlorination method using chlorine is often used. However, this process results in a large amount of chlorine (eg, about 2000-3000 ppm) remaining in the succinimide final product. On the other hand, in the thermal reaction method using no chlorine, chlorine remaining in the final product can be suppressed to an extremely low level (for example, 0 to 30 ppm). Therefore, in order to suppress the chlorine content in the lubricating oil composition to an amount in the range of 0 to 30 mass ppm, it is desirable to use succinimide from polybutenyl succinic anhydride obtained by a thermal reaction method. The succinimide can be further reacted with boric acid, alcohol, aldehyde, ketone, alkylphenol, cyclic carbonate, organic acid, etc., and used as a so-called modified succinimide. In particular, boron-containing alkenyl (or alkyl) succinimide obtained by reaction with boric acid or a boron compound is advantageous in terms of thermal and oxidation stability.

  The lubricating oil composition of the present invention contains alkenyl or alkyl succinimide or a derivative thereof as an essential component, but other ashless dispersants such as alkenyl benzylamine type and alkenyl succinic ester type ashless properties. A dispersant is also used in appropriate combination.

  The alkyl salicylic acid calcium salt detergent which is the component b) in the lubricating oil composition of the present invention contains 0.2 to 7% by mass (preferably, the organic acid metal salt contained in the alkyl salicylic acid calcium salt detergent in the composition). 0.5-5 wt%, more preferably 1.0-3 wt%) and the alkylsalicylic acid calcium salt detergent is a non-sulfurized alkylsalicylic acid having an alkyl group with 14-18 carbon atoms It is a mixture of a calcium salt detergent and a non-sulfurized alkylsalicylic acid calcium salt detergent having an alkyl group having 20 to 28 carbon atoms. In the present invention, the non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms is 90 mol% or more of the alkyl groups contained in the non-sulfurized alkyl salicylic acid calcium salt. It means a non-sulfurized alkyl salicylic acid calcium salt detergent which is an alkyl group having 14 to 18 carbon atoms. Similarly, the non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 20 to 28 carbon atoms means that 90 mol% or more of the alkyl groups contained in the non-sulfurized alkyl salicylic acid calcium salt has carbon atoms. Means a non-sulfurized alkyl salicylic acid calcium salt detergent wherein is a 20-28 alkyl group.

  The non-sulfurized calcium alkylsalicylate is preferably a calcium salt of alkylsalicylic acid produced by utilizing a Kolbe-Schmidt reaction from an alkylphenol obtained by reacting an α-olefin having a predetermined number of carbon atoms with phenol. Usually, an overbased calcium salicylate having an increased total base number is further used as a calcium salicylate detergent by a carbonation step for overbasing using slaked lime and carbon dioxide.

  There is also a method in which alkylphenol is directly neutralized to obtain a Ca salt, and calcium salicylic acid calcium salt is obtained directly in the carbonation step.

  On the other hand, an organic acid having a carbon-nitrogen bond or an alkali metal salt or alkaline earth metal salt of a phenol derivative can also be used in combination with the lubricating oil composition of the present invention in a small amount as a metal detergent. In general, by reacting an amine compound, a base number derived from basic nitrogen can be obtained, and a high base number can be obtained even at a low ash content, which is advantageous. For example, various metal salts such as aminocarboxylic acid metal salts are conceivable. In particular, non-sulfurized alkyl phenates (alkali metal salts or alkaline earth metal salts) having a Mannich base structure are effective. This compound is usually synthesized by Mannich reaction using alkylphenol, formaldehyde, amine or an amine compound, and the reaction product obtained by aminomethylation of the phenol ring is neutralized with a base such as calcium hydroxide to form a metal salt. Can be obtained.

In addition to the metallic detergents described so far, petroleum sulfonic acid or alkylbenzene sulfonic acid or alkyltoluenesulfonic acid alkali metal salt or alkaline earth metal sulfonate can be effectively used in combination with a small amount. .

  Sulfurized phenates used in conventional diesel engine oils are alkali metal salts or alkaline earth metal salts of sulfurized alkylphenols, and calcium salts or magnesium salts are generally known. Sulfurized phenates have good heat resistance, but many of them have a sulfur content exceeding about 3% by mass due to the sulfurization reaction. In the present invention, a small amount thereof can be used in combination with the alkylsalicylic acid calcium salt detergent described above.

  The alkyl salicylic acid calcium salt detergent used in the lubricating oil composition of the present invention has an organic acid metal salt contained in the alkyl salicylic acid calcium salt detergent in an amount of 0.2 to 7% by mass (preferably 0.5%). The type and amount of the two or more alkylsalicylic acid calcium salt detergents described above are selected so as to be present in an amount of ˜5% by mass, more preferably 1.0 to 3% by mass. The above alkyl salicylic acid calcium salt detergent is composed of an organic acid metal salt (generally referred to as a soap component or soap) in an oily medium and a basic agglomerated around the organic acid metal salt. An oily dispersion containing inorganic salt fine particles (eg, calcium carbonate fine particles) in a dispersed state (the content of the oily medium is usually about 25 to 55% by mass). If the amount of the organic acid metal salt in the lubricating oil composition is maintained at a certain level or more even if the addition amount of the calcium alkylsalicylate detergent is reduced to the lubricating oil composition, the lubricating oil composition The deterioration of the high temperature cleanliness (the ability to keep the inside of the engine clean in a high temperature environment) is not significant.

  The zinc phosphate antiwear agent of component c) in the lubricating oil composition of the present invention is selected from the group consisting of zinc dialkyldithiophosphates and zinc dihydrocarbylphosphates. The basic production methods and properties of these zinc phosphate antiwear agents are well known. This zinc phosphate antiwear agent is used in the range of 0.01 to 0.12% by mass in terms of phosphorus content, but from the viewpoint of low phosphorus content and low sulfur content, 0.01 to 0.06 mass. It is preferably used in an amount in the range of%.

  It is desirable that the zinc dialkyldithiophosphate has an alkylaryl group containing an alkyl group having 3 to 18 carbon atoms or an alkyl group having 3 to 18 carbon atoms. Particularly preferred is an alkyl group derived from a secondary alcohol having 3 to 18 carbon atoms, or a primary alcohol having 3 to 18 carbon atoms and 3 to 18 carbon atoms, which is particularly effective for suppressing wear. Dialkyldithiophosphate zinc containing an alkyl group derived from a mixture of a secondary alcohol. Zinc dialkyldithiophosphates from primary alcohols tend to be excellent in heat resistance. These zinc dithiophosphates may be used alone, but are preferably used in a mixture mainly of a secondary alkyl group type and / or a primary alkyl group type.

The lubricating oil composition of the present invention contains 0.01 to 5% by weight (preferably 0.1 to 3% by weight) of an antioxidant phenol compound and / or an antioxidant amine compound as component d). It is characterized by including. In general, a low ash, low phosphorus and low sulfur lubricating oil composition means a reduction in metallic detergents and zinc dithiophosphate, leading to reduced high temperature cleanliness, oxidation stability or wear resistance. Component d) is required to maintain these performances. This component d) is preferably a diarylamine antioxidant and / or a hindered phenol antioxidant. These antioxidants are also effective in improving high temperature cleanability. In particular, diarylamine-based antioxidants are advantageous in this respect because they have a base number derived from nitrogen. On the other hand, hindered phenolic antioxidant is advantageous in prevention of the NO _x oxidation degradation.

Examples of hindered phenol antioxidants include 2,6-di-t-butyl-p-cresol, 4,4′-methylenebis (2,6-di-t-butylphenol), 4,4′-methylenebis. (6-t-butyl-o-cresol), 4,4′-isopropylidenebis (2,6-di-t-butylphenol), 4,4′-bis (2,6-di-t-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 2,2-thio-diethylenebis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], and octyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3- (3,5-di-t- Butyl-4-hydroxy It may be mentioned hindered phenols such as phenyl) octadecyl propionate.

  Examples of diarylamine antioxidants include mixed alkyl diphenylamines having 4 to 9 carbon atoms, p, p′-dioctyldiphenylamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, alkylated α-naphthylamine, And diarylamines, such as alkylation-phenyl-alpha-naphthylamine, can be mentioned. The hindered phenol-based antioxidant and the diarylamine-based antioxidant can be used alone or in combination as desired. Moreover, you may use together oil-soluble antioxidant other than these.

  The lubricating oil composition of the present invention may further contain a molybdenum-containing compound and / or an alkali metal borate hydrate belonging to the multifunctional additive in an amount of 5% by mass or less, particularly 0.01 to 5% by mass. Many of these compounds contain ash, sulfur or the like, but can be used effectively by adjusting the addition amount in consideration of the properties of the entire lubricating oil composition of the present invention.

  The molybdenum-containing compound functions mainly as a friction modifier, an antioxidant or an antiwear agent in the lubricating oil composition, and contributes to an improvement in cleanliness at high temperatures. The content of the molybdenum-containing compound in the lubricating oil composition is desirably in the range of 10 to 2500 ppm in terms of molybdenum metal content. Examples of molybdenum-containing compounds include sulfur-containing molybdenum complexes of succinimide, sulfurized oxymolybdenum dithiocarbamate, sulfurized oxymolybdenum dithiophosphate, amine molybdenum complex compounds, oxymolybdenum diethylate amide, and oxymolybdenum monoglyceride. In particular, the sulfur-containing molybdenum complex of succinimide is effective for improving the cleanliness at high temperatures.

On the other hand, addition of alkali metal borate hydrate is also effective in terms of imparting high temperature cleanliness or base number. Alkali metal borate hydrate represents a compound represented by the compounds synthesized by the methods described in US Pat. Nos. 3,929,650 and 4,089,790. For example, alkali metal or alkaline earth metal neutral sulfonate is carbonated in the presence of an alkali metal hydroxide to obtain an overbased sulfonate, and boric acid is reacted with this to disperse fine particles of alkali metal borate obtained (A desirable ashless dispersant such as succinimide is allowed to coexist during the carbonation reaction). Here, potassium, sodium, etc. are desirable as the alkali metal. Specific examples include a fine particle dispersion having a particle size of about 0.3 μm or less represented by a composition formula: KB ₃ O ₅ .H ₂ O dispersed in neutral calcium sulfonate and succinimide. From the viewpoint of water resistance, those obtained by replacing potassium with sodium are also used favorably.

The lubricating oil composition of the present invention preferably further contains a viscosity index improver in an amount of 20% by mass or less (preferably in the range of 1 to 20% by mass). Examples of the viscosity index improver include polymer compounds such as polyalkyl methacrylate, ethylene-propylene copolymer, styrene-butadiene copolymer, and polyisoprene. Alternatively, a dispersion-type viscosity index improver or a multifunctional viscosity index improver that imparts dispersion performance to these polymer compounds can be used. These viscosity index improvers can be used alone, but any viscosity index improver may be used in combination of two or more.

  The lubricating oil composition of the present invention may further contain various auxiliary additives. Examples of such auxiliary additives include, as antioxidants or antiwear agents, zinc dithiocarbamate, methylenebis (dibutyldithiocarbamate), oil-soluble copper compounds, sulfur compounds (eg, sulfurized olefins, sulfurized esters, Polysulfide), phosphate ester, phosphite ester, organic amide compound (eg, oleylamide) and the like. In addition, compounds such as benzotriazole compounds and thiadiazole compounds that function as metal deactivators can be added. In addition, polyoxyalkylene nonionic surfactants such as polyoxyethylene alkylphenyl ethers functioning as rust inhibitors or demulsifiers and copolymers of ethylene oxide and propylene oxide can also be added. Various amines, amides, amine salts, and derivatives thereof that function as friction modifiers, fatty acid esters of polyhydric alcohols, or derivatives thereof can also be added. Furthermore, various compounds that function as an antifoaming agent or a pour point depressant can also be added. These auxiliary additives are preferably used in an amount of 3% by mass or less (particularly in the range of 0.001 to 3% by mass) with respect to the lubricating oil composition.

(1) Production of Lubricating Oil Composition As a lubricating oil composition used for performance evaluation, using the following base oil and additive component, sulfate ash content is 1.0 mass%, phosphorus content is 0.09 mass%, A lubricating oil composition having a sulfur content of 0.2% by mass and a chlorine content of 5 ppm or less was produced according to the following formulation. The lubricating oil composition was adjusted to show a 5W30 viscosity grade (SAE viscosity grade) by the addition of a viscosity index improver.

(2) Base oil and additives 1) Base oil (mixture of 35:65 by volume ratio of the following base oil A and base oil B)
Base oil A: highly hydrorefined base oil having a kinematic viscosity at 100 ° C. of 4.0 mm ² / s, a viscosity index of 123, and a sulfur content of less than 0.001% by mass Base oil B: kinematic viscosity at 100 ° C. Highly hydrorefined base oil with a viscosity index of 132 and a sulfur content of less than 0.001% by mass at 6.5 mm ² / s 2) Additive

Dispersant A: ethylene carbonate reaction-treated succinimide dispersant (nitrogen content: 0.85 mass%, chlorine content: 30 mass ppm, produced from a polybutene having a number average molecular weight of about 2200 and maleic anhydride by a thermal reaction method. , Which is reacted with a polyalkylene polyamine having an average number of atoms of 6.5 (per molecule), and then the resulting bis-type succinimide is reacted with ethylene carbonate; Implementation of JP-A-7-150166 Manufactured according to Example 17): addition amount 0.0085 mass% (nitrogen content conversion value)
Dispersant B: Boron-containing succinimide-based dispersant (nitrogen content: 1.5 mass%, boron content: 0.5 mass%, chlorine content: less than 5 mass ppm, polybutene and anhydrous maleic acid having a number average molecular weight of about 1300 It is produced from an acid by a thermal reaction method, reacted with a polyalkylene polyamine having an average number of nitrogen atoms of 6.5 (per molecule), and then the obtained bis-type succinimide is reacted with boric acid. Manufactured according to Example 8 of JP-A-7-150166): 0.06% by mass (nitrogen content conversion value)

  Alkyl salicylic acid calcium salt detergent (described in detail in Examples 1 and 2 below and Comparative Example 1): 0.82% by mass (converted to sulfate ash)

ZnDTP: zinc dialkyldithiophosphate (P: 7.2% by mass, Zn: 7.85%, S: 14.4%, secondary alcohol having 3 to 8 carbon atoms used as a raw material): 0.09 mass % (Phosphorus content conversion value)

Antioxidant A: amine compound [dialkyldiphenylamine (alkyl group: mixture of C ₄ and C ₈ ), N: 4.6% by mass, TBN: 180 mgKOH / g]: 0.7% by mass
Antioxidant B: Phenol compound [octyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]: 0.7% by mass

  Mo compound: Sulfur-containing oxymolybdenum-succinimide complex compound (Mo: 5.4% by mass, S: 3.7% by mass, TBN: 45 mgKOH / g): 0.085% by mass

  Viscosity index improver (non-dispersed ethylene propylene copolymer, Paratone 8057)

[Example 1]
Alkyl salicylic acid calcium salt detergent as non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms (TBN: 220 mgKOH / g, containing about 30% by mass of petroleum-based medium, organic acid Non-sulfurized alkyl salicylic acid calcium salt detergent having a metal salt content of 49% by mass) and an alkyl group having 20 to 28 carbon atoms (TBN: 320 mg KOH / g, containing about 35% by mass of petroleum-based medium, Lubricating oil composition according to the present invention (TBN: 9.6 mg KOH / g, organic acid metal salt content: using a mixture of 1: 1 calcium ratio with organic acid metal salt content: 32.5% by mass): 1.1% by mass) was prepared.

[Example 2]
Alkyl salicylic acid calcium salt detergent, non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms (TBN: 225 mg KOH / g, containing petroleum medium of less than about 30% by mass, organic Acid metal salt content: 51% by mass) and a non-sulfurized alkylsalicylic acid calcium salt detergent having an alkyl group having 20 to 28 carbon atoms (TBN: 320 mgKOH / g, containing about 35% by mass petroleum-based medium) , Organic acid metal salt content: 32.5% by mass) and a 1: 1 mixture of calcium amount ratio, lubricating oil composition according to the present invention (TBN: 9.6 mg KOH / g, organic acid metal salt content) : 1.1% by mass).

[Comparative Example 1]
Alkyl salicylic acid calcium salt detergent, non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 20 to 28 carbon atoms (TBN: 320 mg KOH / g, containing about 35% by mass petroleum-based medium, organic acid A comparative lubricating oil composition (TBN: 9.6 mg KOH / g, organic acid metal salt content: 0.7 mass%) was prepared using only the metal salt content: 32.5 mass%.

Evaluation of the content of organic acid metal salt (soap), high temperature cleanliness, and wear resistance was performed by the following methods.
(1) Measurement of organic acid metal salt content (soap content) This is a detergent active ingredient that remains in the rubber membrane by dialyzing mineral oil and low molecular weight components in the metal detergent by the usual rubber membrane dialysis method. A dialysis residue (A) is obtained. On the other hand, carbon dioxide derived from the carbonate in the metallic detergent is measured, and based on this and metal analysis, an overbased component (B) such as calcium carbonate or magnesium carbonate is obtained. The organic acid metal salt (soap) was determined from the difference between (A) and (B).

(2) Evaluation of high temperature cleanliness of lubricating oil composition The cleaning performance of the lubricating oil composition at 300 ° C and 305 ° C was evaluated by a hot tube test (KES-07-803) according to the following method.
A heater block is set perpendicularly to a glass tube having an inner diameter of 2 mm, and sample oil is fed from the lower part of the glass tube at a rate of 0.31 cc / hour and air at a rate of 10 cc / minute. This operation is continued for 16 hours while keeping the temperature of the heater section at a predetermined temperature. Deposits (deposits) adhering to the inside of the glass tube after the end of the test are evaluated with a maximum of 10 points (10 points means a state in which deposits are not observed).

(3) Evaluation of abrasion resistance A shell four-ball test (specified in JPI-5S-32) was performed under conditions of an oil temperature of 90 ° C., a load of 40 kgf, and 1800 rpm for 30 minutes. The evaluation results are shown by wear scar diameter (unit: mm).
(4) Low temperature viscosity The low temperature viscosity (unit: cP) was measured at -35 ° C using an MRV viscometer (as defined in ASTM D4684).

[Table 1]
[Evaluation test results]
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Lubricating oil High temperature cleanability Abrasion resistance (wear scar diameter) Low temperature viscosity Composition 300 ° C 305 ° C
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Example 1 6.0 5.0 0.610 25200
Example 2 6.0 5.0-25100
────────────────────────────────────
Comparative Example 1 5.0 3.0 0.610 Cannot be measured ─────────────────────────────────── ─

  As is clear from the above evaluation test results, the lubricating oil compositions (Examples 1 and 2) of the present invention using two types of calcium alkylsalicylate having different numbers of carbon atoms contained in the alkyl group, It exhibits excellent high temperature cleanliness even under extremely severe temperature conditions such as 305 ° C., has high wear resistance, and has a sufficiently low low temperature viscosity. On the other hand, a lubricating oil composition (Comparative Example 1) using only one type of alkyl salicylic acid calcium salt having an alkyl group having a large number of carbon atoms has high wear resistance but is relatively inferior in terms of high-temperature cleanliness and low-temperature viscosity. Becomes very high.

Claims (12)

At least the following components a) to d) are dissolved or dispersed in a base oil having a sulfur content of 0.1% by mass or less, and the amount of sulfated ash is 0.1 to 1.1% by mass, containing phosphorus. The amount is in the range of 0.01 to 0.12 mass%, the sulfur content is in the range of 0.01 to 0.5 mass%, and the chlorine content is 150 ppm or less, and the sulfur content is 0.005 mass% or less. Lubricating oil composition for lubrication of internal combustion engines operated with fuel oil:
a) An ashless dispersant that is an alkenyl or alkyl succinimide or a derivative thereof is 0.01 to 0.3% by mass in terms of nitrogen content,
b) An alkyl salicylic acid calcium salt detergent having a sulfur content of 3% by mass or less and a total base number of 10 to 350 mg KOH / g is 0.1 to 1% by mass in terms of sulfated ash, provided that the alkyl salicylic acid calcium salt is purified. The organic acid metal salt contained in the agent is present in the composition in an amount of 0.2 to 7% by mass, and the alkyl salicylic acid calcium salt detergent is a non-sulfurized alkyl having an alkyl group having 14 to 18 carbon atoms. A mixture of a calcium salicylic acid detergent and a non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group with 20 to 28 carbon atoms,
c) a zinc phosphate antiwear agent selected from the group consisting of zinc dialkyldithiophosphate and zinc dihydrocarbyl phosphate is 0.01 to 0.12% by mass in terms of phosphorus content, and d) antioxidant phenol 0.01 to 5% by mass of an antioxidant selected from the group consisting of a compound and an antioxidant amine compound,
However, the above-mentioned sulfated ash content, phosphorus content, sulfur content, and mass% of components a) to d) are values based on the total mass of the composition.   The lubricating oil composition according to claim 1, wherein the total base number of the alkyl salicylic acid calcium salt detergent of component b) is in the range of 30 to 300 mg KOH / g.   The lubricating oil composition according to claim 1, wherein the total base number of the non-sulfurized alkylsalicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms is in the range of 100 to 250 mgKOH / g.   The lubricating oil composition according to claim 1, wherein the total base number of the non-sulfurized alkylsalicylic acid calcium salt detergent having an alkyl group having 20 to 28 carbon atoms is in the range of 280 to 350 mgKOH / g.   The calcium salicylic acid calcium salt detergent is a non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms and a non-sulfurized alkyl salicylic acid having an alkyl group having 20 to 28 carbon atoms. The lubricating oil composition according to claim 1, wherein the lubricating oil composition is a mixture having a calcium amount ratio of 2: 8 to 8: 2 with the calcium salt detergent.   The calcium salicylic acid calcium salt detergent is a non-sulfurized alkyl salicylic acid calcium salt detergent having an alkyl group having 14 to 18 carbon atoms and a non-sulfurized alkyl salicylic acid having an alkyl group having 20 to 28 carbon atoms. The lubricating oil composition according to claim 1, which is a mixture of an organic acid metal salt amount ratio of 4: 6 to 8: 2 with a calcium salt detergent.   The ashless dispersant of component a) is obtained by reacting polybutenyl succinic anhydride with polyamine obtained by a thermal reaction method using polybutene and maleic anhydride as raw materials and without contacting chlorine or a chlorine-containing compound. The lubricating oil composition according to claim 1, which is succinimide or a derivative thereof. Furthermore, the lubricating oil composition of Claim 1 which contains a molybdenum containing compound 0.01-5 mass%.   The lubricating oil composition according to claim 1, wherein the total base number is in the range of 1 to 17 mg KOH / g.   The lubricating oil composition according to claim 1, which is a 0W5, 0W10, 0W15, 0W20, 0W30, 5W20, 5W30, 10W20, or 10W30 multigrade engine oil containing a viscosity index improver.   The lubricating oil composition according to claim 1, wherein the lubricating oil composition is used for lubricating a diesel engine operated using fuel oil having a sulfur content of 0.005% by mass or less mounted on a vehicle for running on land.   A method for operating a diesel engine mounted on a vehicle for land travel that is operated using fuel oil having a sulfur content of 0.005 mass% or less, using the lubricating oil composition according to claim 1.