JP2005281614A - Cylinder lubricating oil composition for crosshead type diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder lubricating oil composition for a crosshead diesel engine, which is lower-cost and exhibits higher abrasion resistance and higher seizure resistance in addition to conventional performances. <P>SOLUTION: The lubricating oil composition comprises a lubricating base oil and (A) an ashless dispersant having a boron content of at least 1.5 mass%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cylinder lubricant composition for a crosshead type diesel engine.

  Crosshead diesel engines use cylinder oil that lubricates between the cylinder and piston, and system oil that controls lubrication and cooling of other parts. The cylinder oil is required to have a proper viscosity necessary for lubrication between the cylinder and the piston (piston ring) and a function of maintaining cleanliness necessary for proper movement of the piston and piston ring. Furthermore, this engine has a problem of cylinder corrosion due to acidic components such as sulfuric acid generated by combustion because high sulfur fuel is usually used because of its economic efficiency. In order to prevent this problem, the cylinder oil must have a function of neutralizing acidic components such as sulfuric acid to prevent corrosion.

  On the other hand, recent crosshead type diesel engines have a larger cylinder diameter (for example, a bore size of 70 cm or more) and an increased piston stroke (for example, an average piston speed of 8 m / s or more for further performance improvement). (Extremely long stroke) and increase in combustion pressure (for example, net effective pressure (BMEP) 1.8 MPa or more) tend to be promoted, and increase in combustion pressure leads to an increase in the dropping point of sulfuric acid. The situation is likely to occur. Furthermore, as a measure for preventing the sulfuric acid corrosion, there is a case where the cylinder wall temperature is increased (for example, a cylinder wall temperature of 250 ° C. or more), and the amount of lubricating oil injected into the cylinder is being reduced for economic reasons. As a result, the lubrication environment of cylinders has become more severe.

Furthermore, in recent years, there has been an increasing demand for the use of low-sulfur fuel in coastal areas due to environmental problems. However, when conventional high base number cylinder oil for high-sulfur fuel is used as it is, scuffing, etc. Many cases have been reported where this problem occurs.
Many conventional marine diesel engine oils have low-cost base oils containing an overbased metal detergent as a main component to maintain wear resistance, but recently, salicylate-based sulfonates Marine diesel engine oils containing various types of metal detergents such as phenate, phenate and composite detergents as main components and containing extreme pressure agents and dispersants have been developed (Patent Documents 1 to 5). In recent crosshead type diesel engines as described above, it is required to further exhibit wear prevention and seizure resistance at a lower cost.
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

  In view of these circumstances, the present invention, as a cylinder lubricant for a crosshead type diesel engine, is a cylinder lubricant for a crosshead type diesel engine that has improved the wear resistance and seizure resistance at a lower level in addition to the conventional performance. The purpose is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have found that it is effective to use a specific boron-containing ashless dispersant in order to improve the wear resistance and seizure resistance of the cylinder portion with a lubricating oil. I found out. In addition, only the ashless dispersant containing no boron has a small effect of improving the seizure resistance.

That is, the cylinder lubricating oil composition for a crosshead type diesel engine according to the present invention includes (A) a cylinder lubricating oil composition for a crosshead type diesel engine containing an ashless dispersant having a boron content of 1.5% by mass or more. It is in.
Moreover, it is preferable that the cylinder lubricating oil composition for a crosshead type diesel engine of the present invention further contains an ashless dispersant other than the component (A).
Furthermore, it is preferable that (B) at least one extreme pressure agent is contained.

Hereinafter, the present invention will be described in detail.
The lubricating base oil in the cylinder lubricating oil composition for a crosshead type diesel engine of the present invention (hereinafter also simply referred to as a lubricating oil composition) is not particularly limited, and is a mineral base oil used for ordinary lubricating oil. And / or synthetic base oils can be used.
Specifically, as the mineral base oil, the lubricating oil fraction obtained by subjecting the crude oil to atmospheric distillation obtained under reduced pressure is subjected to solvent removal, solvent extraction, hydrocracking, Produced by isomerizing GTL WAX (Gas Liquid Liquid) produced by one or more treatments such as solvent dewaxing, hydrorefining, etc., or wax isomerized mineral oil, Fischer-Tropsch process, etc. Lubricating oil base oil and the like can be exemplified.

The total aromatic content of the mineral oil base oil is not particularly limited, but is preferably 40% by mass or less, and more preferably 30% by mass or less. Although the total aromatic content may be 0% by mass, it is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more in terms of the solubility of the additive. It is preferably 20% by mass or more. When the total aromatic content of the base oil exceeds 40% by mass, oxidation stability is inferior, which is not preferable.
In addition, the said total aromatic content means the aromatic fraction (aromatic fraction) content measured based on ASTMD2549. 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.

  Further, 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. By including the sulfur content of the mineral oil base oil to some extent, the solubility of the additive can be sufficiently increased.

  Specific examples of 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, Diesters such as diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate; polyol esters such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate; Examples thereof include copolymers of dicarboxylic acids such as dibutyl acid and α-olefins having 2 to 30 carbon atoms; aromatic synthetic oils such as alkylnaphthalene, alkylbenzene and aromatic ester, or mixtures thereof.

  In the present invention, a mineral base oil, a synthetic base oil, or an arbitrary mixture of two or more kinds of lubricating oils selected from these can be used as the lubricating base oil. Examples thereof include 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, and the like.

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 ˜35 mm ² / s. 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 lubrication results in poor lubricity and increases the evaporation loss of the lubricating base oil, which is not preferable.

In the lubricating oil composition of the present invention, the lubricating base oil may have a kinematic viscosity at 100 ° C. of 4 to 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 oil. Examples of the lubricating base oil having a kinematic viscosity at 100 ° C. of less than 4 to 17 mm ² / s include mineral base oils and synthetic base oils such as SAE 10 to 40, and the kinematic viscosity is 5.6 mm ^2. / s or higher, 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, preferably 40 mm ² / s or less, more preferably 35 mm ² / s or less.
In the present invention, a lubricating base oil having a kinematic viscosity at 100 ° C. of less than 4 to 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% by mass or more, If necessary, a lubricating base oil having a kinematic viscosity at 100 ° C. of 17 to 50 mm ² / s can be blended.

  The amount of evaporation loss of the lubricating base oil is preferably 20% by mass or less, more preferably 16% by mass or less, and particularly preferably 10% by mass or less in terms of NOACK evaporation. When the NOACK evaporation amount of the lubricating base oil exceeds 20% by mass, the evaporation loss of the lubricating oil is large, which causes an increase in viscosity and the like, which is not preferable. Here, the NOACK evaporation amount is a value obtained by measuring the evaporation amount of the lubricating oil measured in accordance with ASTM D 5800.

  The viscosity index of the lubricating base oil is not particularly limited, but the value is preferably 80 or more, more preferably 90 or more, still more preferably 100 or more so that excellent viscosity characteristics can be obtained from low temperature to high temperature. It is. 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, etc. Although about 150 to 250 such as a base oil can be used, it is preferably 120 or less, more preferably 110 or less in terms of the solubility and storage stability of the additive.

The component (A) in the present invention is a boron-containing ashless dispersant, and the boron content is required to be 1.5% by mass or more. Specific examples of the component (A) include boron-modified compounds obtained by modifying an ashless dispersant that does not contain boron described below with a boron compound such as boric acid or borate.
As the ashless dispersant that does not contain boron, any ashless dispersant that does not contain boron used in lubricating oils can be used. For example, linear or branched alkyl having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms. And nitrogen-containing compounds having at least one group or alkenyl group in the molecule or derivatives thereof, Mannich dispersants, modified products of alkenyl succinimide, and the like.
In the case where the carbon number of the alkyl group or alkenyl group of the nitrogen-containing compound or derivative thereof is less than 40, the solubility in the lubricating oil base oil is reduced, whereas in the case where the carbon number of the alkyl group or alkenyl group exceeds 400, The low-temperature fluidity of the lubricating oil composition is deteriorated, which is not preferable. The alkyl group or alkenyl group may be linear or branched, but is preferably derived from, for example, an olefin oligomer such as propylene, 1-butene, isobutylene, or a co-oligomer of ethylene and propylene. Examples include branched alkyl groups and branched alkenyl groups.

More specifically, as the component (A), for example, one or two or more compounds selected from the following components (I-1) to (I-3) are boric acid or borate. What modified | denatured with boron compounds, such as, can be used.
(I-1) Succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof,
(I-2) benzylamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof,
(I-3) A polyamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof.

Examples of the component (I-1) include compounds represented by the formula (1) or (2).

In the formula (1), R ²⁰ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350, and h represents an integer of 1 to 5, preferably 2 to 4. On the other hand, in the formula (2), R ²¹ and R ²² each independently represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and particularly preferably a polybutenyl group. I represents an integer of 0 to 4, preferably 1 to 3.

The component (I-1) includes a so-called monotype succinimide represented by the formula (1) in which succinic anhydride is added to one end of the polyamine, and a formula (2) in which succinic anhydride is added to both ends of the polyamine. The so-called bis-type succinimide represented by formula (1)) is included, and the lubricating oil composition of the present invention may contain any of them or a mixture thereof.
There is no restriction | limiting in particular in the manufacturing method of succinimide which is these (I-1) components, For example, the compound which has a C40-C400 alkyl group or an alkenyl group is made to react with maleic anhydride at 100-200 degreeC. It is obtained by reacting the obtained alkyl succinic acid or alkenyl succinic acid with a polyamine.
Specific examples of the polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

Specific examples of the component (I-2) include compounds represented by the formula (3).

In the formula (3), R ²³ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350, and j represents an integer of 1 to 5, preferably 2 to 4.
There is no restriction | limiting in particular in the manufacturing method of benzylamine which is this (I-2) component, For example, after making polyolefin, such as a propylene oligomer, a polybutene, or an ethylene-alpha-olefin copolymer, react with phenol to make alkylphenol, This is obtained by reacting formaldehyde with a polyamine such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine by a Mannich reaction.

Specific examples of the component (I-3) include compounds represented by the formula (4).
^{_{R 24 -NH- (CH 2 CH 2}} NH) k -H (4)
In the formula (4), R ²⁴ represents an alkyl group or an alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350, and k represents an integer of 1 to 5, preferably 2 to 4.
The production method of the polyamine which is the component (I-3) is not particularly limited. For example, after chlorinating a polyolefin such as a propylene oligomer, polybutene and an ethylene-α-olefin copolymer, ammonia, ethylenediamine, diethylenetriamine is added thereto. , Triethylenetetramine, tetraethylenepentamine, or a polyamine such as pentaethylenehexamine.

  Examples of the derivatives of nitrogen-containing compounds mentioned as an example of the ashless dispersant not containing boron include, for example, monocarboxylic acids having 1 to 30 carbon atoms (fatty acids, etc.), oxalic acid, phthalic acid, A C2-C30 polycarboxylic acid such as trimellitic acid or pyromellitic acid or an anhydride thereof, or an ester compound, a C2-C6 alkylene oxide, a hydroxy (poly) oxyalkylene carbonate, etc. A modified compound by a so-called oxygen-containing organic compound obtained by neutralizing or amidating part or all of the remaining amino group and / or imino group; the remaining amino group by allowing phosphoric acid to act on the aforementioned nitrogen-containing compound And / or a so-called phosphoric acid-modified compound obtained by neutralizing or amidating part or all of the imino group; Sulfur-modified compounds obtained by action of; modified by and oxygen-containing organic compound to the nitrogen-containing compounds described above, modified phosphoric acid, modified compounds combining two or more modifying selected from sulfur-modified and the like.

In the present invention, the component (A) is a boron-containing ashless dispersant having a boron content of 1.5% by mass or more, and the boron content is preferably 1.8% by mass or more. By using such a material having a high boron content, it is possible to obtain a lower-cost composition that can realize higher wear resistance and reduce the blending amount of the boron-containing ashless dispersant itself. In addition, (A) component here may contain 10-90 mass%, Preferably it is 30-70 mass% dilution oil (for example, mineral oil, synthetic oil, etc.), The boron content in (A) component Usually means the boron content with diluent oil.
The component (A) is preferably a compound obtained by modifying the component (I-1) listed above with a boron compound, and in particular, a bis-type succinimide-based ashless component represented by the general formula (2). A boric acid-modified compound as a powder is particularly preferable because it can significantly improve wear resistance and seizure resistance.

Further, as the component (A), the mass ratio (B / N ratio) between the boron content and the nitrogen content is not particularly limited, but is preferably 0.5 to 1, more preferably 0.7 to 0. .9. The higher the B / N ratio is, the easier it is to improve the wear prevention and seizure resistance.
In the lubricating oil composition of the present invention, the content of the component (A) is preferably 0.001 to 0.1% by mass, more preferably 0.005 to 0.05 as the boron content based on the total amount of the composition. It is 0.01 mass%, More preferably, it is 0.01-0.04 mass%. Furthermore, when using the ashless dispersant other than the component (A) and the component (B) described later, even if the boron content is reduced to 0.02% by mass or less, sufficient wear resistance and seizure resistance can be obtained. This is particularly preferable because it can be maintained and coking at a high temperature can be further suppressed and a lower-cost composition can be obtained.

In the present invention, an ashless dispersant other than the component (A), for example, an ashless dispersant having a boron content of less than 1.5% by mass, and an ashless dispersant not containing boron listed above may be blended. Among them, it is particularly preferable to add a bis-type succinimide ashless dispersant represented by the general formula (2) because coking at a high temperature is more easily suppressed.
(A) When mix | blending ashless dispersing agents other than a component, there is no restriction | limiting in particular in the compounding quantity, However, Preferably it is 0.005-0.1 mass% by a nitrogen conversion amount on the basis of a composition whole quantity, More preferably It is 0.005-0.05 mass%, More preferably, it is 0.01-0.03 mass%.

In the present invention, in addition to the addition of the component (A), (B) at least one extreme pressure agent can be further contained.
As the extreme pressure agent (B) that can be used in the lubricating oil composition of the present invention, any antiwear 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, dithiocarbamate, zinc dithiocarbamate, molybdenum dithiocarbamate, disulfide , Polysulfides, sulfurized olefins, sulfurized fats and oils, and the like.
In the present invention, it is preferable to use zinc dithiophosphate and / or polysulfides.

  In the lubricating oil composition of the present invention, when the component (B) is used, the content thereof is not particularly limited, but is 0.05 to 5% by mass, preferably 0.1 to 2% based on the total amount of the composition. It is 0.2 mass%, More preferably, it is 0.2-1 mass%. In the present invention, when the component (B) is contained, if it is less than 0.1% by mass, the effect of further improving the wear prevention and seizure resistance is small, whereas if it exceeds 5% by mass, the composition Since the high temperature cleanliness of the resin deteriorates significantly, it is not preferable.

  The lubricating oil composition of the present invention is an optional component commonly used in lubricating oils depending on its purpose in order to further improve its performance or to add other required performance in addition to the above configuration. Further additives can be added. Examples of such additives include metal detergents, antioxidants, friction modifiers, viscosity index improvers, corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, antifoaming agents, and An additive such as a colorant may be mentioned.

The metal detergent is not particularly limited, and is a known alkali metal or alkaline earth metal sulfonate detergent, alkali metal or alkaline earth metal phenate detergent, alkali metal or alkaline earth metal salicylate detergent, Examples thereof include alkali metal or alkaline earth metal naphthenate detergents, alkali metal or alkaline earth metal phosphonate detergents, and mixtures thereof (including complex types).
Examples of the alkali metal herein include sodium and potassium, and examples of the alkaline earth metal include calcium, magnesium, barium and the like, preferably an alkaline earth metal, and preferably calcium or magnesium. Particularly preferred.
The base number of the metal detergent is not particularly limited, but is usually preferably 0 to 500 mgKOH / g, more preferably 150 to 450 mgKOH / g, and particularly preferably 250 to 450 mgKOH / g. The base number referred to here is 7. 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 present invention, it is preferable to use an overbased sulfonate detergent and / or an overbased phenate detergent having a base number of 200 to 450 mgKOH / g, and an overbased sulfonate system having a base number of 350 to 450 mgKOH / g. It is particularly preferred to use a detergent and / or an overbased phenate detergent having a base number of 200 to 300 mg KOH / g.
In the present invention, the content of the metal detergent is not particularly limited, but is usually 1 to 30% by mass, preferably 5 to 25% by mass, based on the total amount of the composition, based on the diluted oil mixture. Preferably it is 10-25 mass% or more, More preferably, it is 15-25 mass%.

Examples of the antioxidant include ashless antioxidants such as phenols and amines, and metal antioxidants such as copper and molybdenum. These contents are usually 0.1 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. These contents are usually 0.1 to 5% by mass based on the total amount of the composition.

  As the viscosity index improver, polymethacrylate viscosity index improver, olefin copolymer viscosity index improver, styrene-diene copolymer viscosity index improver, styrene-maleic anhydride copolymer viscosity index improver or poly Examples thereof include alkylstyrene viscosity index improvers. The weight average molecular weight of these viscosity index improvers is usually 800 to 1,000,000, preferably 100,000 to 900,000. Moreover, content of a viscosity index improver is 0.1-20 mass% normally on the composition whole quantity basis.

Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiadiazole, or imidazole compounds.
Examples of the rust preventive 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, or 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 thereof include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and 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 Examples thereof include alkyl ethers.

  When these additives are contained in the lubricating oil 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 the corrosion inhibitor, the rust inhibitor, and the demulsifier, The metal deactivator 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 kinematic viscosity at 100 ° C. of the lubricating oil 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. ˜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.

  In addition, the base number of the lubricating oil composition of the present invention is not particularly limited, but in order to add excellent high temperature cleanliness and acid neutralization performance even when using a high sulfur fuel containing asphaltenes. Is preferably 5 to 100 mgKOH / g, more preferably 10 mgKOH / g or more, further preferably 20 mgKOH / g or more, more preferably 80 mgKOH / g or less, and still more preferably 50 mgKOH / g or less. Here, the base number refers to a base number measured by ASTM D-2896.

  The amount of sulfated ash in the lubricating oil 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, and particularly preferably 3% by mass or more, preferably It is 20 mass% or less, More preferably, it is 10 mass% or less. The sulfated ash here refers to 5. of JIS K2272. The value measured by the method specified in “Testing method for sulfated ash” is mainly attributable to the metal-containing additive.

  The lubricating oil composition of the present invention is excellent in spreadability to sliding surfaces at high temperatures, is excellent in wear prevention and seizure resistance, and is suitable as a cylinder lubricating oil composition for crosshead type diesel engines, In particular, the latest model with an increased bore size of 70 cm or more, an ultra-long stroke with an average piston speed of 8 m / s or more, and even 8.5 m / s or more, and combustion pressure is a net effective pressure (BMEP). A two-stroke cycle diesel engine operated under a condition that satisfies any or all of the following conditions: 1.8 MPa or more, further 1.9 MPa or more, cylinder wall temperature 250 ° C. or more, further 260 ° C. or more, particularly 270 ° C. or more Particularly effective as a cylinder lubricating oil composition for engines.

  Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these.

(Examples 1-2, Comparative Examples 1-2)
The lubricating oil compositions (Examples 1 and 2) of the present invention having the compositions shown in Table 1 and comparative lubricating oil compositions (Comparative Examples 1 and 2) were prepared. About the obtained composition, the seizure load was measured with the high-speed reciprocation test machine on the conditions shown below, and the result was written together in Table 1. The base oil used here is a combination of SAE 30 Group I base oil (sulfur content 0.03% by mass or more, saturation content less than 90% by mass, viscosity index 80 to 120) and bright stock. With the formulation of the agent, the composition was adjusted to have a kinematic viscosity at 100 ° C. of 20 mm ² / s. Package A is an additive package consisting only of overbased sulfonate and overbased phenate, and is added so that the base number of the composition is 70 mgKOH / g.

<Test conditions for high-speed reciprocating tester>
1. Disc diameter: 190 mm, rotation speed: 1600 rpm
2. Maximum sliding speed: 12.5m / s (position of diameter 150mm)
Average sliding speed: 8.0 m / s
3. Reciprocating speed (ring swing speed): 100 rpm
4). Liner material: Turkaloy C (material used in actual equipment)
Ring material: flake graphite cast iron (material used in actual machine)
Root mean square roughness: 0.38-0.40 μm
5). Oil supply: 1 drop per minute (about 0.5 mg / s)

  As is clear from the results of Table 1, in the composition containing no component (A) in the present invention, 2% by mass and 5% by mass of succinimide containing no boron are contained (Comparative Examples 1 and 2). Then, the seizure load is as low as about 4 MPa, and the effect of improving the seizure resistance of succinimide containing no boron is not observed. However, when the component (A) is contained, the seizure load is increased to 5 MPa (Example 1), and even if the boron-containing succinimide is halved, the seizure load is further increased when the extreme pressure agent is used in combination. It turns out that a load becomes high (Example 2).

Claims (3)

  A cylinder lubricating oil composition for a crosshead type diesel engine, wherein the lubricating base oil contains (A) an ashless dispersant having a boron content of 1.5% by mass or more.   The cylinder lubricating oil composition for a crosshead type diesel engine according to claim 1, further comprising an ashless dispersant other than the component (A). The cylinder lubricating oil composition for a crosshead type diesel engine according to any one of claims 1 and 2, further comprising (B) at least one extreme pressure agent.