JP2008239775A - Lubricating oil composition for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a lubricating oil composition for a diesel engine, which comprises a salicylate-based cleaning agent having a high base number and zinc dithiophosphate and suppresses increase in viscosity and reduction in base number by interaction of additives when the base number is ≥15 mgKOH/g. <P>SOLUTION: The lubricating oil composition for a diesel engine comprises a lubricant base oil, a salicylate-based cleaning agent to be mixed with the base oil, having a base number of ≥100 mgKOH/g and zinc dithiophosphate, has a base number of ≥15 mgKOH/g, contains a phenol-based antioxidant having an ester bond or zinc dithiophosphate containing a secondary alkyl group and does not contain an ashless dispersant or contains <0.005 mass% calculated as nitrogen of an ashless dispersant. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a lubricating oil composition for diesel engines, and more particularly to a lubricating oil composition for diesel engines such as marine diesel engines such as fishing boat diesel engines and trunk piston engines.

Diesel engines that use fuels with a sulfur content of 0.01% by mass or more, such as C heavy oil and A heavy oil, have a base number of at least 10 mgKOH / g or more in order to suppress corrosion of the cylinder due to sulfuric acid generated during combustion. In general, lubricating oils for internal combustion engines are recommended.
In recent years, these lubricating oils for internal combustion engines have been required to be more excellent in heat resistance because the combustion temperature has become higher due to higher efficiency. In addition, although anti-polishing is being considered for recent marine internal combustion engines, this reduces the amount of lubricating oil consumed, resulting in the advantage of reducing the number of lubrication oil replenishments and the amount of replenishment. The lubrication conditions of the engine will become more severe. Furthermore, since it is inevitable that the amount of soot mixed with the long-term use of the lubricating oil is unavoidable, a means for suppressing abnormal wear and viscosity increase due to soot is also required.
From this point of view, conventional marine diesel engine oils use salicylate additives with high oxidation stability and heat resistance, use of high base number lubricants, high dispersibility of sludge and sludge dispersibility The use of succinimide dispersants or the use of extreme pressure agents such as zinc dithiophosphate has been studied (for example, see Patent Documents 1 to 15).

However, according to the study by the present inventors, when a high base number salicylate detergent, zinc dithiophosphate, and a succinimide dispersant are used in combination, the base number of the lubricating oil is 15 mgKOH / g or more. In some cases, it has been found that the viscosity of the lubricating oil increases due to the interaction of these additives as well as the inclusion of soot. This increase in viscosity is unlikely to occur when the base number of the lubricating oil is less than 15 mg KOH / g or when a salicylate detergent with a low base number is used, and it has also been found to be a phenomenon peculiar to the above case. . Furthermore, it has been found that the base number of the lubricating oil decreases as the viscosity increases.
On the other hand, in some internal combustion engines, oil purifiers such as centrifugal cleaners, various filters, and strainers are used to separate and remove insoluble components due to deterioration of lubricating oil and contamination with soot and water that causes deterioration. Sometimes. In such an oil purifier such as a centrifugal cleaner, when the oil purifying conditions are loose, removal of impurities such as sludge, wear powder or moisture becomes insufficient, so that the oil purifying conditions are more strict. However, in an oil purifying apparatus such as a centrifugal cleaner, the additive and water in the lubricating oil are easily contacted at a high temperature to cause hydrolysis, or precipitation due to the interaction of the additive is likely to occur. The initial performance of the lubricating oil, such as anti-wear performance and high-temperature cleaning performance, may be reduced early. If an excessive amount of a succinimide dispersant is contained in the lubricating oil, the water separability is deteriorated, so that the function of the oil purifier cannot be fully exhibited. Therefore, in an internal combustion engine equipped with the oil purifier, soot dispersion The use of a lubricating oil that excessively uses a succinimide-based dispersant, which is expected to have good properties and sludge dispersibility, has to be restricted.
JP 2002-275491 A JP-T-2002-515933 Japanese translation of PCT publication No. 2002-501974 Japanese translation of PCT publication No. 2002-500026 JP 2002-241780 A JP 2005-281614 A JP-A-11-29784 Japanese Patent Laid-Open No. 8-253782 JP 59-27994 JP-A-8-283964 Japanese Patent Laid-Open No. 11-1694 Japanese Patent Laid-Open No. 10-102082 Japanese Patent Laid-Open No. 10-121081 JP-A-10-121082 JP-A-9-111275

An object of the present invention is to provide a high base number salicylate detergent for enhancing heat resistance, zinc dithiophosphate for enhancing extreme pressure, or succinimide for further improving soot dispersibility and sludge dispersibility. Even when an ashless dispersant such as a dispersant is used and the base number of the lubricating oil is 15 mg KOH / g or more, an increase in the viscosity of the lubricating oil due to the interaction of these additives can be suppressed. An object of the present invention is to provide a lubricating oil composition for a diesel engine that can enhance the base performance retention performance of the product.
Another problem of the present invention is the use of an ashless dispersant such as a succinimide-based dispersant that can be expected to have dispersibility in soot and insoluble matter in a diesel engine equipped with an oil purifier where water separability is important. Among these, even when a high base number salicylate detergent and zinc dithiophosphate are used in combination and the base number of the lubricating oil is 15 mg KOH / g or more, the lubricating oil due to the interaction of these additives An object of the present invention is to provide a lubricating oil composition for a diesel engine that can suppress an increase in viscosity and further enhance the retention performance of the base number of the composition.

  According to the study by the present inventors, the increase in the viscosity of the lubricating oil by the combined use of a high base number salicylate detergent and zinc dithiophosphate is succinimide to improve dispersibility of wrinkles and insoluble matter. When used in combination with ashless dispersants such as zinc-based dispersants, it occurs regardless of the type of zinc dithiophosphate, and additional ashless dispersants such as succinimide-based dispersants and general amine-based antioxidants and bisphenol-based oxidation It was found that the inhibitor could not be suppressed. And it became clear that this viscosity increase could be suppressed only by using a specific antioxidant. In addition, the increase in the viscosity of the lubricating oil by using a high base number salicylate-based detergent and zinc dithiophosphate in combination with an ashless dispersant such as a succinimide-based dispersant, or when using only a slight amount, It was found that the increase in viscosity can be suppressed by using a specific zinc dithiophosphate, depending on the type of zinc dithiophosphate. However, it has also been found that when an ashless dispersant such as a succinimide dispersant is excessively used, this viscosity increase inhibiting effect disappears.

That is, according to the present invention, the composition contains a lubricating base oil, a salicylate detergent with a base number of 100 mgKOH / g or more and a zinc dithiophosphate compounded in the base oil, and the base number of the composition is 15 mgKOH / g or more of a diesel engine lubricating oil composition comprising a phenolic antioxidant having an ester bond (hereinafter abbreviated as composition (A)). Is provided).
Moreover, according to this invention, the composition (A) containing 0.005 mass% or more of ashless dispersing agents as nitrogen amount is provided.
Furthermore, according to the present invention, the composition contains a lubricating base oil, a salicylate detergent with a base number of 100 mgKOH / g or more, and zinc dithiophosphate, and a base number of the composition is 15 mgKOH / g. The diesel engine lubricating oil composition as described above, wherein the zinc dithiophosphate contains zinc dithiophosphate having a secondary alkyl group, and the composition contains no ashless dispersant or 0.005 mass as a nitrogen amount. The lubricating oil composition for diesel engines (hereinafter sometimes abbreviated as composition (B), characterized in that the composition (A) and the composition (B) are collectively referred to as the composition of the present invention) May be provided).

The composition (A) of the present invention can suppress an increase in viscosity due to the interaction between additives when a large amount of highly basic salicylate detergent and zinc dithiophosphate are used in combination with the above-described configuration, and , The reduction of the base number can be suppressed. Moreover, while suppressing the increase in viscosity, a large amount of a highly basic salicylate-based detergent having excellent heat resistance can be blended, and zinc dithiophosphate is also used in combination to improve extreme pressure, wear resistance or antioxidant properties. Can do.
In addition to the above, the composition (B) of the present invention does not contain an ashless dispersant or is slightly limited even if it is contained, so for a diesel engine equipped with an oil purifier such as a centrifuge, Hydrolysis stability in the oil purifier is improved, and performance that can withstand long-term use can be maintained.
Therefore, the composition of the present invention is used for marine vessels such as diesel engines for fishing boats and trunk piston diesel engines using fuels such as A heavy oil and C heavy oil having a sulfur content of 0.01% by mass, preferably 0.1% by mass or more. It can be suitably used not only for an internal combustion engine for a diesel engine but also as a lubricating oil composition for a power generation diesel engine and a railway vehicle diesel engine using the fuel.

Hereinafter, the present invention will be described in detail.
The composition of the present invention is for a marine diesel engine such as a fishing boat diesel engine or a trunk piston diesel engine using a fuel having a sulfur content of 0.01% by mass, or a power generation diesel engine or railcar using the fuel. It can be suitably used for a diesel engine.
Examples of the fuel having a sulfur content of 0.01% by mass or more include A heavy oil, B heavy oil, C heavy oil, asphalt, crude oil, and the like. The sulfur content is preferably 0.05 to 5% by mass, more preferably Is 0.1 to 3.5% by mass. The fuel usually contains asphaltene and residual carbon at least 0.02% by mass (JIS K 2270) of residual carbon (0.2% by mass of 10% residual carbon).

The lubricating base oil used in the composition of the present invention is not particularly limited, and a mineral base oil and / or a synthetic base oil used for ordinary lubricating oils can be used.
Mineral oil base oils include solvent oil removal, solvent extraction, hydrocracking, solvent dewaxing, hydrogen removal of lubricating oil fractions obtained by vacuum distillation of atmospheric residue obtained by atmospheric distillation of crude oil. Lubricating base oil produced by isomerizing GTL WAX (Gas Liquid Wax) produced by one or more treatments such as hydrorefining, wax isomerized mineral oil, Fischer-Tropsch process, etc. Can be illustrated.

The total aromatic content of the mineral oil base oil is not particularly limited, but is preferably 40% by mass or less, more preferably 30% by mass or less. The total aromatic content may be 0% by mass, but is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and particularly preferably 20% by mass or more in terms of the solubility of the additive. . When the total aromatic content of the base oil exceeds 40% by mass, the oxidation stability may be inferior.
The total aromatic content means the aromatic fraction content measured according to ASTM D2549. Usually, this aromatic fraction includes alkylbenzene, alkylnaphthalene, anthracene, phenanthrene, alkylated products thereof, compounds in which four or more benzene rings are condensed, and heterogeneous compounds such as pyridines, quinolines, phenols and naphthols. Compounds having aromatics are included.
The sulfur content in the mineral oil base oil is not particularly limited, but is preferably 1% by mass or less, and more preferably 0.5% by mass or less. Although 0 mass% may be sufficient as a sulfur content, Preferably it is 0.1 mass% or more, More preferably, it is 0.2 mass% or more. When the mineral oil base oil contains sulfur to some extent, the solubility of the additive can be sufficiently increased.

  Synthetic base oils include polybutene or hydrides thereof; poly α-olefins such as 1-octene oligomers and 1-decene oligomers or hydrides thereof; ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl Diesters such as adipate and di-2-ethylhexyl sebacate; polyol esters such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate and pentaerythritol pelargonate; dicarboxylics such as dibutyl maleate Examples include copolymers of acids and α-olefins having 2 to 30 carbon atoms; aromatic synthetic oils such as alkylnaphthalenes, alkylbenzenes, and aromatic esters, or mixtures thereof.

  In the present invention, a mineral base oil, a synthetic base oil, a fat or oil, or an arbitrary mixture of two or more kinds of lubricating oils selected from these can be used as the lubricating base oil. For example, one or more mineral base oils, one or more synthetic base oils, a mixed oil of one or more mineral base oils and one or more synthetic base oils may be mentioned.

The kinematic viscosity of the lubricating base oil is not particularly limited, but the kinematic viscosity at 100 ° C. is preferably 4 to 50 mm ² / s, more preferably 6 to 40 mm ² / s, and particularly preferably 8 to 35 mm ² / s. It is. When the kinematic viscosity at 100 ° C. of the lubricating base oil exceeds 50 mm ² / s, the low-temperature viscosity characteristics deteriorate, whereas when the kinematic viscosity is less than 4 mm ² / s, an oil film is formed at the lubricating location. Insufficient lubricity is inferior, and evaporation loss of the lubricating base oil may increase.

The lubricating base oil used in the present invention has a kinematic viscosity at 100 ° C. of 4 mm ² / s or more and less than 17 mm ² / s and / or a kinematic viscosity at 100 ° C. of 17 to 50 mm ² / s. It is preferable to contain a lubricating base oil. Examples of the lubricating base oil having a kinematic viscosity at 100 ° C. of 4 mm ² / s or more and less than 17 mm ² / s include mineral base oils such as SAE 10-40 and synthetic base oils. 6 mm ² / s or more, more preferably 9.3 mm ² / s or more, preferably 14 mm ² / s or less, more preferably 12.5 mm ² / s. Examples of the lubricating base oil having a kinematic viscosity at 100 ° C. of 17 to 50 mm ² / s include mineral base oils and synthetic base oils such as SAE50 and bright stock, and the kinematic viscosity is preferably It is 20 mm ² / s or more, more preferably 25 mm ² / s or more, preferably 40 mm ² / s or less, more preferably 35 mm ² / s or less.
In the composition of the present invention, a lubricating base oil having a kinematic viscosity at 100 ° C. of 4 mm ² / s or more and less than 17 mm ² / s as a main component, for example, 50% by mass or more based on the total amount of the base oil, more preferably 70 Lubricating base oil having a kinematic viscosity at 100 ° C. of 17 to 50 mm ² / s can be blended if necessary.

  The viscosity index of the lubricating base oil is not particularly limited, but the value is preferably 80 or higher, more preferably 90 or higher, and still more preferably 100 or higher so that excellent viscosity characteristics can be obtained from low temperature to high temperature. The upper limit of the viscosity index is not particularly limited, and is about 135 to 180, such as normal paraffin, slack wax, GTL wax, or isoparaffin mineral oil obtained by isomerizing these, complex ester base oil, HVI-PAO base oil However, it is preferably 120 or less, and particularly preferably 110 or less, from the viewpoint of the solubility and storage stability of the additive.

The composition of the present invention contains a salicylate detergent having a base number of 100 mgKOH / g or more.
The structure of the salicylate detergent is not particularly limited, but a metal salt of salicylic acid having 1 to 2 alkyl groups having 1 to 40 carbon atoms, preferably an alkali metal salt or alkaline earth metal salt, particularly a magnesium salt and A calcium salt is preferably used.

  As the salicylate-based detergent, those containing a dialkyl salicylic acid metal salt are preferable in that they are superior in high-temperature cleanability and hydrolysis stability. That is, a salicylate detergent in which the constituent ratio of the dialkyl salicylic acid metal salt exceeds 0 and is 100 mol% or less, preferably 5 mol% or more, more preferably 10 mol% or more is desirable. On the other hand, those having a high composition ratio of the monoalkyl salicylic acid metal salt are preferred from the viewpoint of superior low temperature viscosity characteristics. For example, the composition ratio of the monoalkyl salicylic acid metal salt is 85 to 100 mol%, and the composition ratio of the dialkyl salicylic acid metal salt is 0 to An alkyl salicylic acid metal salt and / or its (over) basic salt is preferably 15 mol%, and the constituent ratio of the 3-alkyl salicylic acid metal salt is 40 to 100 mol%.

The monoalkyl salicylic acid metal salt means an alkyl salicylic acid metal salt having one alkyl group such as a 3-alkyl salicylic acid metal salt, a 4-alkyl salicylic acid metal salt, and a 5-alkyl salicylic acid metal salt. The ratio is usually 85 to 100 mol%, preferably 88 to 98 mol%, more preferably 90 to 95 mol% with respect to 100 mol% of the alkylsalicylic acid metal salt. Alkylsalicylic acid metal salts other than monoalkylsalicylic acid metal salts such as dialkylsalicylic acid The composition ratio of the metal salt is usually 0 to 15 mol%, preferably 2 to 12 mol%, more preferably 5 to 10 mol%.
Moreover, the composition ratio of 3-alkyl salicylic acid metal salt is 40-100 mol% normally with respect to 100 mol% of alkyl salicylic acid metal salt, Preferably it is 45-80 mol%, More preferably, it is 50-60 mol%.
The total composition ratio of the 4-alkyl salicylic acid metal salt and the 5-alkyl salicylic acid metal salt corresponds to the composition ratio excluding the 3-alkyl salicylic acid metal salt and the dialkyl salicylic acid metal salt with respect to 100 mol% of the alkyl salicylic acid metal salt. Usually, it is 0 to 60 mol%, preferably 20 to 50 mol%, more preferably 30 to 45 mol%. By containing a small amount of a metal salt of dialkyl salicylic acid, it is possible to obtain a composition that is excellent in high-temperature cleanliness and low-temperature characteristics and excellent in hydrolytic stability. By setting the composition ratio of 3-alkyl salicylate to 40 mol% or more, 5 -The composition ratio of the alkyl salicylic acid metal salt can be relatively lowered, and the oil solubility can be improved.

The alkyl group in the alkyl salicylic acid metal salt constituting the salicylate-based detergent has 10 to 40 carbon atoms, preferably 10 to 19 carbon atoms or 20 to 30 carbon atoms, more preferably 14 to 18 carbon atoms or 20 to 20 carbon atoms. The alkyl group having 26 to 26 carbon atoms is preferable in view of excellent low-temperature viscosity characteristics, and the alkyl group having 14 to 18 carbon atoms is preferable in terms of excellent dispersibility.
Examples of the alkyl group having 10 to 40 carbon atoms include decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group. Group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, and triacontyl group. These alkyl groups may be linear or branched, and may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group. In the present invention, the desired metal salicylate is used. A secondary alkyl group is particularly preferred from the viewpoint of easily obtaining a salt.

  Examples of the metal in the alkyl salicylic acid metal salt include alkali metals such as sodium and potassium, and alkaline earth metals such as calcium and magnesium. Calcium and magnesium are preferable, and calcium is particularly preferable.

The salicylate-based detergent can be produced by a known method and is not particularly limited. For example, 1 mol or more of a polymer such as ethylene, propylene, butene, or a copolymer such as a copolymer or a copolymer of 10 to 10 carbon atoms with respect to 1 mol of phenol. 40 olefins, preferably a method of alkylating with a linear α-olefin such as an ethylene polymer and carboxylating with carbon dioxide gas or the like, or 1 mol or more of the olefin, preferably the linear chain with respect to 1 mol of salicylic acid Alkyl salicylic acid mainly composed of monoalkyl salicylic acid obtained by an alkylation method using an α-olefin is reacted with a metal base such as an alkali metal or alkaline earth metal oxide or hydroxide, or Alkali metal salts such as sodium and potassium salts, It can be obtained by replacing a potassium metal salt with an alkaline earth metal salt.
Here, the reaction ratio of phenol or salicylic acid and olefin is preferably controlled to, for example, 1: 1 to 1.15 (molar ratio), more preferably 1: 1.05 to 1.1 (molar ratio). The constituent ratio of the monoalkyl salicylic acid metal salt and the dialkyl salicylic acid metal salt can be controlled to a desired ratio. Further, by using a linear α-olefin as the olefin, the composition ratio of the 3-alkyl salicylic acid metal salt, the 5-alkyl salicylic acid metal salt and the like can be easily controlled to a desired ratio of the present application, and the preferred secondary alkyl in the present invention It is particularly preferable because a metal salt of an alkyl salicylic acid having the above can be obtained as a main component.
In addition, when a branched olefin is used as the olefin, it is easy to obtain only a 5-alkyl salicylic acid metal salt, but the oil solubility is improved by mixing a 3-alkyl salicylic acid metal salt or the like so as to have the desired configuration of the present application. This is not preferable in that the manufacturing process is diversified.

The salicylate detergent is an alkali metal or alkaline earth gold salicylate (neutral salt) obtained as described above, an excess of an alkali metal or alkaline earth metal salt, an alkali metal or an alkaline earth metal base ( A basic salt obtained by heating an alkali metal or alkaline earth metal hydroxide or oxide) in the presence of water, or the neutral salt in the presence of carbon dioxide gas, boric acid or borate. Also included are overbased salts obtained by reacting with a base such as an alkali metal or alkaline earth metal hydroxide.
These reactions are usually carried out in a solvent such as an aliphatic hydrocarbon solvent such as hexane, an aromatic hydrocarbon solvent such as xylene, a light lubricating base oil, etc., and its metal content is 1.0-20. It is desirable to use a material having a mass% of 2.0 to 16% by mass.

  As the most preferable salicylate detergents, the composition ratio of the monoalkyl salicylic acid metal salt is 85 to 95 mol% and the composition of the dialkyl salicylic acid metal salt is excellent in the balance between high temperature detergency, hydrolysis stability and low temperature viscosity characteristics. The composition ratio of 3-alkyl salicylic acid metal salt, which is a monoalkyl salicylic acid metal salt, is 5 to 15 mol%, and the composition ratio of 4-alkyl salicylic acid metal salt and 5-alkyl salicylic acid metal salt is Alkyl salicylic acid metal salts that are 35 to 45 mol% and / or their (over) basic salts. The alkyl group here is particularly preferably a secondary alkyl group.

In the present invention, the base number of the salicylate detergent needs to be 100 mgKOH / g or more, preferably 150 to 500 mgKOH / g, more preferably 160 to 450 mgKOH / g, and is selected from these. 1 type, 2 or more types, or 3 or more types can be used together. For example, a salicylate detergent having a base number of 100 to less than 200 mgKOH / g, a salicylate detergent having a base number of 200 to 300 mgKOH / g, a salicylate detergent having a base number of more than 300 mgKOH / g and less than 450 mgKOH / g You may use together 1 type, 2 types or more selected, or 3 types or more. Even when a salicylate detergent of less than 100 mg KOH / g is used, the increase in viscosity due to the interaction with zinc dithiophosphate is small, but this is not only excluded from the subject of the present invention, but also the deterioration of wear prevention and In order to make the base number 15 mgKOH / g or more, the amount to be contained becomes large, which is not preferable from the viewpoint of economy.
In the present invention, when a (over) basic salicylate detergent having a base number of 200 to 300 mgKOH / g is used, a (over) basic salicylate detergent having a base number of less than 200 mgKOH / g or more than 300 mgKOH / g Contains a (super) basic salicylate detergent with a base number of 200 to 300 mgKOH / g, because the viscosity increase due to the interaction with zinc dithiophosphate and the like tends to be relatively large compared to the case of using the Even in this case, it is important to sufficiently suppress the increase in viscosity.
The base number referred to here is JIS K2501, “Petroleum products and lubricating oils-Neutralization number test method”. Means the base number measured by the perchloric acid method according to the above.
In the composition of the present invention, the content of the salicylate detergent is usually 1 to 30% by mass, preferably 5 to 15% by mass, and more preferably 7 to 10% by mass, based on the total amount of the composition.

In the composition of the present invention, the above salicylate detergent may be used alone, but other metal detergents such as phenate detergent and sulfonate detergent may be used in combination. However, when an overbased salicylate and a sulfonate detergent are blended in a large amount, the micelle stability is deteriorated and precipitation is likely to occur. Therefore, it is particularly preferable to use a phenate detergent in combination.
Examples of the phenate detergent include alkylphenol sulfide alkali obtained by reacting sulfur with an alkylphenol having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 10 to 18 carbon atoms. An earth metal salt, or an alkaline earth metal salt of a Mannich reaction product of an alkylphenol obtained by reacting the alkylphenol with formaldehyde, particularly a magnesium salt and / or a calcium salt, is preferably used.
The base number of the phenate detergent is usually 0 to 500 mgKOH / g, preferably 20 to 450 mgKOH / g, more preferably 150 to 300 mgKOH / g.
Although there is no restriction | limiting in particular when using a phenate type | system | group detergent, 0.1-30 mass% normally on the basis of the composition whole quantity, Preferably it is 1-10 mass%, Most preferably, it is 1.5-3 mass %.

  In the present invention, when a salicylate detergent and a phenate detergent are used in combination, the base number burden ratio is not particularly limited, but the salicylate detergent is used for the total base number resulting from the salicylate detergent and the phenate detergent. The base rate burden rate of the detergent is preferably 50% or more, more preferably 60% or more, still more preferably 70% or more, preferably 95% or less, more preferably 90% or less. By increasing the base number burden ratio of the salicylate detergent, a lubricating oil composition having excellent heat resistance can be obtained, and by using a phenate detergent together, a lubricating oil composition that can further suppress an increase in viscosity can be obtained. Can be obtained.

Sulfonate detergents that can be used in the compositions of the present invention include neutral alkaline earth metal sulfonates, basic alkaline earth metal sulfonates, overbased alkaline earth metal sulfonates, or mixtures of two or more thereof. The base number is usually selected from the range of 0 to 500 mgKOH / g.
As the sulfonate detergent, calcium sulfonate detergent and magnesium sulfonate detergent are preferable, and calcium sulfonate detergent is particularly preferable.
The content in the case of using a sulfonate detergent is not particularly limited, but is usually selected from a range of 0.1 to 30% by mass. Is good.

The composition of the present invention contains zinc dithiophosphate for imparting extreme pressure properties, antiwear properties or antioxidant properties.
Examples of zinc dithiophosphate include zinc dithiophosphate represented by the formula (1).

In the formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent an alkyl group having 1 to 18 carbon atoms, an aryl group or an alkylaryl group having 7 to 18 carbon atoms.
Examples of the alkyl group include 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, tetradecyl group, pentadecyl group. Group, hexadecyl group, heptadecyl group, and octadecyl group. Particularly, an alkyl group having 3 to 8 carbon atoms is generally used. The alkyl group may be linear or branched and may be a primary (primary) alkyl group or a secondary (secondary) alkyl group.
In the production of zinc dithiophosphate represented by the formula (1), a mixture of α-olefins may be used as a raw material when introducing R ¹ , R ² , R ³ and R ^4. ) Is a mixture of zinc dialkyldithiophosphates having alkyl groups with different structures.

Examples of the aryl group include a phenyl group and a naphthyl group.
As the alkylaryl group, for example, tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, Examples include an undecylphenyl group and a dodecylphenyl group. These alkyl groups may be linear or branched and include all substituted isomers.

  Specific compounds of zinc dithiophosphate include, for example, zinc di (2-ethylhexyl) dithiophosphate, zinc di (1,3-dimethylbutyl) dithiophosphate, zinc diisopropyldithiophosphate, or a mixture of two or more thereof. It is done.

In the composition (A) of the present invention, the zinc dithiophosphate is preferably a zinc dialkyldithiophosphate having a primary alkyl group or a secondary alkyl group, and in any case, it has an ester bond described later. By using a phenolic antioxidant, it is possible to suppress an increase in viscosity due to the interaction between the highly basic salicylate detergent and zinc dithiophosphate.
When using the phenolic antioxidant which has an ester bond, if the ashless dispersing agent mentioned later is used together, the further viscosity increase inhibitory effect will be exhibited. However, even if an amine-based antioxidant or a bisphenol-based antioxidant is used instead of the phenol-based antioxidant having an ester bond, the above-described increase in viscosity is not exhibited.

In the composition (B) of the present invention, the zinc dithiophosphate is a zinc dialkyldithiophosphate having a secondary alkyl group, particularly a zinc dialkyldithiophosphate having a secondary alkyl group having 3 to 6 carbon atoms, particularly 3 and / or carbon atoms. Alternatively, it is essential to use zinc dialkyldithiophosphate having 6 secondary alkyl groups. Instead of this, even if a zinc dialkyldithiophosphate having a primary alkyl group is used, the effect of suppressing the increase in viscosity is not exhibited.
When the composition (B) of the present invention contains an ashless dispersant, which will be described later, excessively, the effect of inhibiting the increase in viscosity due to the zinc dialkyldithiophosphate having a secondary alkyl group is impaired by the interaction. Even if it is not included at all, its content must be limited.
As described above, since the interaction between the additives is complicatedly entangled with the composition (A) and the composition (B), the combination of the additives and the selection of the application to be used are extremely important.

In the composition of the present invention, the content of the zinc dithiophosphate is not particularly limited, but is usually 0.01 to 0.2% by mass, preferably 0.02 to 0.1% by mass as the phosphorus amount based on the total amount of the composition. %, Particularly preferably 0.03 to 0.06% by mass.
The metal amount (M) in the composition resulting from the metal detergent containing the salicylate detergent or the metal amount (M ′) in the composition resulting from the salicylate detergent and the zinc dithiophosphate The mass ratio (M / P) or (M ′ / P) to the amount of phosphorus (P) is not particularly limited, but is preferably 4 or more, more preferably 10 or more, still more preferably 15 or more, and preferably 100 Below, more preferably 50 or less, and still more preferably 30 or less. The higher the M / P or M ′ / P ratio, the more the viscosity increase can be improved.

In the composition (A) of the present invention, it is important to contain a phenolic antioxidant having an ester bond. It can also be added to the composition (B).
As the phenolic antioxidant having an ester bond, any known one for lubricating oil can be used and is not particularly limited. For example, among the compounds represented by the formula (2) or the formula (3) Preferred are one or more compounds selected.

In the formula (2), R ³⁰ represents an alkyl group having 1 to 4 carbon atoms, R ³¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ³² represents an alkylene group having 1 to 6 carbon atoms, R ³³ represents an alkyl group or alkenyl group having 1 to 24 carbon atoms. In formula (3), R ⁹ and R ¹³ each independently represent an alkyl group having 1 to 4 carbon atoms, and R ¹⁰ and R ¹⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ¹¹ and R ¹² each independently represents an alkylene group having 1 to 6 carbon atoms, and X represents an alkylene group having 1 to 18 carbon atoms or —R ¹⁵ —S—R ¹⁶ —. However, R ¹⁵ and R ¹⁶ are each independently an alkylene group having 1 to 6 carbon atoms.

Examples of the alkyl group having 1 to 4 carbon atoms of R ³⁰ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. However, a tert-butyl group is preferred because the composition is excellent in oxidation stability.
Examples of R ³¹ include a hydrogen atom or an alkyl group having 1 to 4 carbon atoms as described above, and a methyl group or a tert-butyl group is preferable because the composition is excellent in oxidation stability.
The alkylene group having 1 to 6 carbon atoms represented by R ³² may be linear or branched. For example, a methylene group, a methylmethylene group, an ethylene group (dimethylene group), an ethylmethylene group, a propylene group (Methylethylene group), trimethylene group, butylene group, pentylene group, hexylene group. R ³² is more preferably an alkylene group having 1 to 2 carbon atoms, such as a methylene group, a methylmethylene group, or an ethylene group (dimethylene group) in that the compound represented by the formula (2) can be produced with a small number of reaction steps. preferable.

The alkyl group or alkenyl group having 1 to 24 carbon atoms represented by R ³³ may be linear or branched, and the position of the double bond of the alkenyl group may be arbitrary. For example, a methyl group, an ethyl group, Propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl Alkyl groups such as icosyl group, hencosyl group, docosyl group, tricosyl group, tetracosyl group; vinyl group, propenyl group, isopropenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group , Undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, Tadeseniru group, hexadecenyl group, heptadecenyl group, octadecenyl group, octadecadienyl group, nonadecenyl group, icosenyl, henicosenyl group, docosenyl, tricosenyl group, and an alkenyl group such as a tetracosenyl group.
R ³³ is a linear or branched alkyl group having 4 to 18 carbon atoms, for example, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, or a nonyl group, because of its excellent solubility in base oils. Decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, and octadecyl group are preferable, and a linear or branched alkyl group having 6 to 12 carbon atoms is more preferable. A branched alkyl group of formula 6-12 is particularly preferred.

Among the compounds represented by formula (2), R ³² is an alkylene group having 1 to 2 carbon atoms, and R ³³ is a linear or branched alkyl group having 6 to 12 carbon atoms. It is particularly preferable that R ³² is an alkylene group having 1 to 2 carbon atoms and R ³³ is a branched alkyl group having 6 to 12 carbon atoms.

  Examples of the compound represented by the formula (2) include (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-hexyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl). ) Isohexyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-heptyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isoheptyl acetate, (3-methyl-5 -Tert-butyl-4-hydroxyphenyl) acetate n-octyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate isooctyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) 2-ethylhexyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-nonyl, (3-methyl-5-te t-butyl-4-hydroxyphenyl) isononyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-decyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetic acid Isodecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-undecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetoisodecyl, (3-methyl-5-tert -Butyl-4-hydroxyphenyl) acetic acid n-dodecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate isododecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionic acid n-hexyl, isohexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate N-heptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5- tert-butyl-4-hydroxyphenyl) n-octylpropionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isooctylpropionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) ) 2-ethylhexyl propionate, n-nonyl (3-methyl-5-tert-butyl-4-hydroxyphenyl), isononyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, ( 3-methyl-5-tert-butyl-4-hydroxyphenyl) propionic acid n-deci Isodecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, n-undecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5- tert-butyl-4-hydroxyphenyl) isoundecyl propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) n-dodecyl propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) ) Isododecyl propionate, n-hexyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, isohexyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5- Di-tert-butyl-4-hydroxyphenyl) acetic acid n-heptyl, (3,5-di-tert-butyl- 4-Hydroxyphenyl) isoheptyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-octyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate isooctyl, (3 , 5-Di-tert-butyl-4-hydroxyphenyl) acetic acid 2-ethylhexyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid n-nonyl, (3,5-di-tert-butyl) -4-hydroxyphenyl) isononyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-decyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetodecyl, ( 3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid n-undecyl, (3,5-di-tert-butyl-4-hydroxyphenyl) vinegar Isoundecyl acid, n-dodecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, isododecyl (3,5-di-tert-butyl-4-hydroxyphenyl) acetate, (3,5-di- tert-butyl-4-hydroxyphenyl) n-hexyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) isohexyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) ) N-heptyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) isoheptyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) n-octyl propionate, Isooctyl 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl) 4-hydroxyphenyl) propionate 2-ethylhexyl, (3,5-di-tert-butyl-4-hydroxyphenyl) propionate n-nonyl, (3,5-di-tert-butyl-4-hydroxyphenyl) propion Isononyl acid, n-decyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, isodecyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5- N-undecyl di-tert-butyl-4-hydroxyphenyl) propionate, isoundecyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4- Hydroxyphenyl) n-dodecyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) propiate Phosphate isododecyl, or a mixture of two or more kinds may be preferably mentioned.

Examples of the alkyl group having 1 to 4 carbon atoms of R ⁹ and R ¹³ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. From the viewpoint that the composition is excellent in oxidation stability, both are preferably tert-butyl groups.
Examples of R ¹⁰ and R ¹⁴ include a hydrogen atom or an alkyl group having 1 to 4 carbon atoms as described above. From the viewpoint that the composition is excellent in oxidative stability, each is independently a methyl group or a tert-butyl group. Preferably there is.
The alkylene group having 1 to 6 carbon atoms of R ¹¹ and R ¹² may be linear or branched, and examples thereof include various alkylene groups described above for R ³² individually. R ¹¹ and R ¹² are each independently an alkylene group having 1 to 2 carbon atoms, for example, in that the compound represented by the formula (3) can be produced with few reaction steps and the raw material is easily available. A methylene group, a methylmethylene group, and an ethylene group (dimethylene group) are more preferable.
The alkylene group having 1 to 18 carbon atoms of X may be linear or branched. For example, methylene group, methylmethylene group, ethylene group (dimethylene group), ethylmethylene group, propylene group (methylethylene group), trimethylene Group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group and octadecylene group. C1-6 alkylene group, for example, methylene group, methylmethylene group, ethylene group (dimethylene group), ethylmethylene group, propylene group (methylethylene group), trimethylene group, butylene group because of easy availability of raw materials More preferred are a pentylene group and a hexylene group, an ethylene group (dimethylene group), a trimethylene group, a linear butylene group (tetramethylene group), a linear pentylene group (pentamethylene group), a linear hexylene group (hexamethylene group), etc. The straight chain alkylene group having 2 to 6 carbon atoms is particularly preferable.

Among the compounds represented by the formula (3), particularly preferred as a compound when X is an alkylene group having 1 to 18 carbon atoms is tetramethylene bis (3- (3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate) or hexamethylene bis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) represented by formula (5) Is mentioned.

When X in Formula (3) is —R ¹⁵ —S—R ¹⁶ —, the alkylene group having 1 to 6 carbon atoms which is R ¹⁵ and R ¹⁶ may be linear or branched. , Each individually includes various alkylene groups as described above for R ³² . R ¹⁵ and R ¹⁶ are each independently an alkylene group having 1 to 3 carbon atoms, such as a methylene group, a methylmethylene group, an ethylene group, because raw materials for producing the compound of formula (3) are easily available. (Dimethylene group), ethylmethylene group, propylene group (methylethylene group), and trimethylene group are more preferable.

Among the alkylphenols represented by the formula (3), as a particularly preferable compound when X is —R ¹⁵ —S—R ¹⁶ —, for example, thiodiethylene bis (3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)] compound.

Examples of other phenol-based antioxidants having an ester bond other than the compound represented by formula (2) or formula (3) include pentaerythritol tetrakis (3- (3,5) represented by formula (7). -Di-tert-butyl-4-hydroxyphenyl) propionate) compounds.

  Although there is no restriction | limiting in particular in content of the said phenolic antioxidant which has the said ester bond in the composition of this invention, 0.01-5 mass% normally on the basis of a composition whole quantity, Preferably it is 0.05-2 mass% More preferably, it is 0.1 to 1% by mass. Even if an amount exceeding 5% by mass is contained, an effect corresponding to the content cannot be expected, and if it is less than 0.01% by mass, a sufficient effect may not be obtained. It is preferable to be in the range.

In the composition (A) of the present invention, a further increase in the viscosity increase can be obtained by using an ashless dispersant in combination.
As the ashless dispersant, any ashless dispersant used in lubricating oils can be used. For example, a nitrogen-containing compound having at least one linear or branched alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule or a derivative thereof can be mentioned.
Examples of the nitrogen-containing compound include succinimide, benzylamine, polyamine, Mannich base, and derivatives thereof include boron compounds such as boric acid and borate, (thio) phosphoric acid, Derivatives obtained by acting phosphorus compounds such as (thio) phosphate, organic acids, hydroxy (poly) oxyalkylene carbonate, and the like. In the present invention, one or two or more arbitrarily selected from these can be blended.

The alkyl group or alkenyl group has 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms. When the alkyl group or alkenyl group has less than 40 carbon atoms, the solubility of the compound in the lubricating base oil decreases, whereas when the alkyl group or alkenyl group has more than 400 carbon atoms, the composition of the present invention Low temperature fluidity may be deteriorated. This alkyl group or alkenyl group may be linear or branched, but specifically, preferred are derived from olefin oligomers such as propylene, 1-butene and isobutylene, and co-oligomers of ethylene and propylene. And a branched alkyl group and a branched alkenyl group.
As the ashless dispersant, mono-type and / or bis-type succinimide-based ashless dispersants, particularly bis-type succinimide-based ashless dispersants are preferable from the viewpoint of high-temperature cleanliness, and succinimide-based ashless dispersants The powder may or may not contain boron, but it is particularly preferable that it contains boron from the standpoint of seizure resistance.
In the composition (A) of the present invention, the content when an ashless dispersant is blended is not particularly limited, but is usually 0.1 to 10% by mass, preferably 0.5 to 4% by mass based on the total amount of the composition. %, More preferably 1 to 3% by mass, and the nitrogen content is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and further preferably 0.015% by mass or more. In addition, it is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and further preferably 0.04% by mass or less. Even if the content of the ashless dispersant is less than the above, it is possible to exert a favorable viscosity increase inhibiting effect, but by making it in the above range, a further viscosity increasing inhibiting effect will be exhibited, and the soot dispersion performance is also Be improved.

  In the composition (B) of the present invention, if the ashless dispersant is excessively used, the effect of the zinc dialkyldithiophosphate having a secondary alkyl group described above may be inhibited. Further, when used in a diesel engine equipped with an oil purifier such as a centrifugal separator, there is a risk that hydrolysis stability is impaired and initial lubricating oil performance cannot be maintained for a long time. Accordingly, the composition (B) of the present invention desirably uses no ashless dispersant, or even if it is used, the amount of nitrogen is less than 0.005% by mass based on the total amount of the composition.

The composition of the present invention can suppress the increase in viscosity of the composition due to the interaction between the highly basic salicylate detergent and zinc dithiophosphate and enhance the retention of the base number according to the above configuration. Any additive commonly used in lubricating oils can be added to the compositions of the present invention to improve or for other purposes.
Examples of such additives include antioxidants other than those described above, antiwear agents or extreme pressure agents other than those described above, friction modifiers, viscosity index improvers, corrosion inhibitors, rust inhibitors, antiemulsifiers, metal additives Activators, antifoaming agents, or coloring agents.

  Antioxidants other than those mentioned above include phenolic antioxidants having no ester bond, such as 2,6-ditertiarybutyl-4-methylphenol (DBPC), 4,4′-methylenebis- (2,6- Examples thereof include phenolic antioxidants such as ditertiary butylphenol), amine antioxidants such as alkyldiphenylamine and (alkyl) phenyl-α-naphthylamine, and metal antioxidants. Content when using antioxidant other than the above is 0.1-5 mass% normally on the composition whole quantity basis.

As the antiwear agent or extreme pressure agent other than those described above, any antiwear agent or extreme pressure agent used in lubricating oils can be used. For example, sulfur-based, phosphorus-based, sulfur-phosphorus extreme pressure agents and the like can be used. Specifically, phosphites, thiophosphites, dithiophosphites, trithiophosphites Esters, phosphate esters, thiophosphate esters, dithiophosphate esters, trithiophosphate esters, amine salts thereof, metal salts thereof, derivatives thereof, dithiocarbamates, disulfides, polysulfides, sulfurized olefins And sulfurized oils and the like.
In the composition of the present invention, the content when an antiwear agent or extreme pressure agent is used is not particularly limited, but is usually 0.01 to 5% by mass based on the total amount of the composition.

  Examples of the friction modifier include ashless friction modifiers such as fatty acid esters, aliphatic amines, and fatty acid amides, and metal friction modifiers such as molybdenum dithiocarbamate and molybdenum dithiophosphate. Content when using a friction modifier is 0.01-5 mass% normally on the composition whole quantity basis.

  Examples of the viscosity index improver include, for example, a polymethacrylate viscosity index improver, an olefin copolymer viscosity index improver, a styrene-diene copolymer viscosity index improver, and a styrene-maleic anhydride copolymer viscosity index improver. Or a polyalkyl styrene type viscosity index improver etc. are mentioned. The weight average molecular weight of the viscosity index improver is usually 800 to 1,000,000, preferably 100,000 to 900,000. Moreover, the mixture ratio in the case of using a viscosity index improver is 0.1-20 mass% normally on the basis of the total amount of the composition.

Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiadiazole, or imidazole compounds.
Examples of the rust inhibitor include 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 alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.
Examples of metal deactivators include imidazoline, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis. Examples include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, or β- (o-carboxybenzylthio) propiononitrile.
Examples of antifoaming agents include silicone oil, alkenyl succinic acid derivatives, esters of polyhydroxy aliphatic alcohols and long chain fatty acids, methyl salicylate and o-hydroxybenzyl alcohol, aluminum stearate, potassium oleate, N-dialkyl-allylamine Nitroaminoalkanols, aromatic amine salts of isoamyloctyl phosphate, alkylalkylene diphosphates, metal derivatives of thioethers, metal derivatives of disulfides, fluorine compounds of aliphatic hydrocarbons, triethylsilane, dichlorosilane, alkylphenyl polyethylene glycol ether sulfides, fluoro An alkyl ether is mentioned.

  When these additives are contained in the composition of the present invention, the content is based on the total amount of the composition, and is usually 0.005 to 5% by mass for a corrosion inhibitor, a rust inhibitor and an anti-emulsifier, respectively. The activator is usually selected from the range of 0.005 to 1% by mass, and the antifoaming agent is usually selected from the range of 0.0005 to 1% by mass.

The base number of the composition of the present invention is 15 mgKOH / g or more in order to add excellent high temperature cleanliness and acid neutralization performance even when using a high sulfur fuel containing asphaltenes, preferably It is 15-100 mgKOH / g, More preferably, it is 20-80 mgKOH / g, More preferably, it is 20-70 mgKOH / g. Here, the base number refers to a base number measured by ASTM D-2896.
The kinematic viscosity at 100 ° C. of the composition of the present invention is not particularly limited, but is preferably 6 to 50 mm ² / s, more preferably 9.3 to 30 mm ² / s, and particularly preferably 12.5 to 21.9 mm ^2. / S. The kinematic viscosity at 100 ° C. here refers to the kinematic viscosity at 100 ° C. as defined in ASTM D-445.
The amount of sulfated ash in the composition of the present invention is not particularly limited, but is preferably 1.2% by mass or more, more preferably 2% by mass or more, particularly preferably 3% by mass or more, preferably 20% by mass or less, More preferably, it is 10 mass% or less. The sulfated ash here refers to JIS K2272 5. The value measured by the method specified in “Testing method for sulfated ash” is mainly attributable to the metal-containing additive.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these at all.
Examples 1-9, Comparative Examples 1-12, Reference Examples 1-2
According to the composition shown in Table 1 and Table 2, the lubricating oil composition of the present invention (Examples 1 to 9), the comparative lubricating oil composition (Comparative Examples 1 to 12), and the reference lubricating oil composition (Reference Example) 1-2) were prepared respectively. The obtained composition was added to JIS K 2514, 4. Forcibly deteriorated at 165.5 ° C. for 48 hours, and the composition after the test was measured for kinematic viscosity, acid value, base value, pentane insoluble matter (Method B), and lacquer. The results are shown in Tables 1 and 2. Moreover, the viscosity ratio of the composition after the test with respect to new oil and the base number retention were calculated from the obtained results and the kinematic viscosity and base number of the new oil. The results are shown in Tables 1 and 2.

In addition, 1) to 10) in Table 1 and 1) to 12) in Table 2 are as follows.
(Table 1)
1) Kinematic viscosity at 100 ° C: 7.2mm ² / s, viscosity index 100
2) Kinematic viscosity at 100 ° C: 10.5mm ² / s, viscosity index 95
3) 100 ° C. kinematic viscosity: 32mm ² / s, viscosity index 95
4) Overbased Ca salicylate mixture of 170BN, 230BN and 320BN
5) 255BN overbased Ca phenate
6) Zinc dialkyldithiophosphate having 1ryC8 alkyl group
7) Zinc dialkyldithiophosphate having 2ryC3 / C6 alkyl group
8) Boron-containing succinimide dispersant (nitrogen content: 2 mass%, boron content 0.5 mass%)
9) Octyl-3- (3,5-ditertiarybutyl-4-hydroxyphenyl) propionate
10) Dialkyldiphenylamine (Table 2)
1) Kinematic viscosity at 100 ° C: 7.2mm ² / s, viscosity index 100
2) Kinematic viscosity at 100 ° C: 10.5mm ² / s, viscosity index 95
3) 100 ° C. kinematic viscosity: 32mm ² / s, viscosity index 95
4) 230BN overbased Ca salicylate
5) Zinc dialkyldithiophosphate having 1ryC8 alkyl group
6) Zinc dialkyldithiophosphate having 2ryC3 / C6 alkyl group
7) Boron-containing succinimide dispersant (nitrogen content: 2 mass%, boron content 0.5 mass%)
8) Octyl-3- (3,5-ditertiarybutyl-4-hydroxyphenyl) propionate
9) Thiodiethylene bis [3- (3,5-ditertiarybutyl-4-hydroxyphenyl) propionate]
10) 4,4'-Methylenebis- (2,6-ditertiary butylphenol)
11) Dialkyldiphenylamine
12) Neutral Ca salicylate of 60BN

(Result of reference example)
From the results of Reference Examples 1 and 2 in Tables 1 and 2, the content of the metal detergent including the highly basic salicylate detergent is small, the base number (perchloric acid method) is less than 15 mgKOH / g, or the calcium content is In the case of using a lubricating oil composition of less than 0.5% by mass (Reference Example 1) or a salicylate detergent having a base number (perchloric acid method) of less than 100 mgKOH / g (Reference Example 2), the deterioration The subsequent increase in viscosity is small, and the increase in viscosity due to the interaction between the salicylate detergent and zinc dithiophosphate as in the subject of the present invention is small. Accordingly, an object of the present invention is to solve a peculiar phenomenon in which an increase in viscosity due to interaction with zinc dithiophosphate becomes remarkable when a large amount of a metal detergent containing a highly basic salicylate is contained.

(Result of composition (A))
From the results of Tables 1 and 2, the composition (A) of the present invention using the phenolic antioxidant having an ester bond (Examples 1 to 5, 8 and 9) has a very small increase in viscosity after deterioration. Moreover, it turns out that the retention of a base number is also high. In addition, it has been confirmed that the above effect is further enhanced by including 0.005% by mass or more of the ashless dispersant as the amount of nitrogen. On the other hand, it is a composition other than the composition (B) and does not contain an ashless antioxidant (Comparative Examples 1, 3, 4, 6-9), and an phenol having an ester bond as an antioxidant. In the composition using the amine antioxidant instead of the system antioxidant (Comparative Examples 2, 5, 11 and 12) and the composition using the bisphenol antioxidant having no ester bond (Comparative Example 10) It can be seen that the increase in viscosity is larger than that of the composition using the phenolic antioxidant having an ester bond, and the retention of the base number is also low.
When a phenolic antioxidant having an ester bond is not used, the effect of using an ashless dispersant is not recognized or less than the effect of the present invention, and a phenolic antioxidant having an ester bond is used. In the case where the ashless dispersant is contained in a specific amount or more, the effect of the alkyl group type of zinc dithiophosphate is not recognized. For the first time, the use of a phenolic antioxidant with an ester bond as an antioxidant suppresses an increase in viscosity and a decrease in base number due to the interaction between a highly basic salicylate detergent and zinc dithiophosphate. It can be seen that it was possible to achieve an exceptional effect that was completely unpredictable.

(Result of composition (B))
From the results of Tables 1 and 2, the composition (B) (Examples 6 and 7) that does not contain an ashless dispersant and uses a zinc dialkyldithiophosphate having a secondary alkyl group (Examples 6 and 7) has a very small increase in viscosity after deterioration. Moreover, it turns out that the retention of a base number is also high. In contrast, a composition using a zinc dialkyldithiophosphate having a primary alkyl group and containing no ashless dispersant (Comparative Example 8), a composition using an amine-based antioxidant in the composition of Comparative Example 8 (Comparison) Example 12) Alternatively, even when a zinc dialkyldithiophosphate having a secondary alkyl group is used, the composition containing the ashless dispersant in a specific amount or more (Comparative Examples 3, 6, and 7) is compared with the composition (B). It can be seen that the viscosity increase is large and the base number retention is low. From this, it can be seen that the effect of using the zinc dialkyldithiophosphate having a secondary alkyl group is inhibited by the ashless dispersant.

Claims (7)

  A lubricating oil for diesel engines containing a lubricating base oil, a salicylate-based detergent having a base number of 100 mgKOH / g or more, and zinc dithiophosphate blended in the base oil, and having a base number of the composition of 15 mgKOH / g or more A diesel engine lubricating oil composition comprising a phenolic antioxidant having an ester bond.   The composition of Claim 1 which contains 0.005 mass% or more of ashless dispersing agents as nitrogen amount.   A lubricating oil for diesel engines containing a lubricating base oil, a salicylate-based detergent having a base number of 100 mgKOH / g or more, and zinc dithiophosphate blended in the base oil, and having a base number of the composition of 15 mgKOH / g or more It is a composition, wherein the zinc dithiophosphate contains zinc dithiophosphate having a secondary alkyl group, and the composition contains no ashless dispersant or less than 0.005% by mass as the amount of nitrogen. A lubricating oil composition for diesel engines.   The composition according to claim 3, wherein the composition is for a diesel engine equipped with an oil purifier.   The composition according to any one of claims 1 to 4, comprising a phenate detergent having a base number of 100 to 300 mgKOH / g.   The mass ratio (M / P) of the metal content (M) attributed to the salicylate detergent in the composition to the phosphorus content (P) attributed to zinc dithiophosphate is 4 or more, The composition according to any one of claims 1 to 5.   The composition according to any one of claims 1 to 6, wherein the composition is for a diesel engine equipped with an anti-polishing device.