JP5913338B2 - Cylinder lubricating oil composition for crosshead type diesel engine - Google Patents

Description

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

  The crosshead type diesel engine uses cylinder oil that lubricates between the cylinder and the piston, and system oil that controls lubrication and cooling of other parts. Here, the cylinder oil is required to have the proper viscosity necessary for lubrication between the cylinder and the piston (piston ring) and the function of maintaining the cleanliness necessary for proper movement of the piston and piston ring. It is done. Furthermore, since the high-sulfur fuel is usually used in the crosshead type diesel engine because of its economical efficiency, it has a problem of cylinder corrosion due to acidic components such as sulfuric acid generated by combustion. In order to solve this problem, the cylinder oil also needs a function of neutralizing acidic components such as sulfuric acid to be generated and preventing corrosion.

  On the other hand, in recent crosshead type diesel engines, in order to further improve the performance, the cylinder diameter is increased (for example, bore size is 70 cm or more) and the piston stroke is increased (for example, average piston speed is 8 m / s or more). And an increase in combustion pressure (for example, net average effective pressure (BMEP) of 1.8 MPa or more) tends to be promoted, and the increase in combustion pressure causes an increase in the dropping point of sulfuric acid. Corrosion is more likely to occur. In addition, as a measure for preventing the sulfuric acid corrosion, there is a case where the wall temperature of the cylinder is increased (for example, the cylinder wall temperature is 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 is becoming more severe.

  More recently, due to environmental issues, the IMO (International Maritime Organization) has begun to regulate the emissions of marine engines and to limit the sulfur level of the fuel in order to reduce sulfur dioxide emissions. At present, it is obliged to use fuel with a sulfur content of 4.5% by mass or less even in high-sulfur fuel in general sea areas, and low-sulfur fuel with 1% by mass or less of fuel sulfur must be used in regulated sea areas centering on the North Sea. Is no longer.

  When using high sulfur fuel, it is necessary to use cylinder oil with a high base number (generally 70 mgKOH / g) to neutralize the acidic components produced by combustion. It is necessary to switch to a cylinder oil of 40 mg KOH / g). This means that if a low-sulfur fuel (with a sulfur content of 1% by mass or less) is used while a cylinder oil with a high base number (70 mgKOH / g) is used, the excess base component of the high base number cylinder oil will be the top land of the piston. This is because it accumulates as hard ash, and the cylinder liner may be polished to cause excessive wear. Conversely, if a high sulfur fuel is used with the cylinder oil having a low base number (40 mgKOH / g), neutralization of sulfuric acid generated by combustion becomes insufficient and wear due to corrosion occurs.

  In the future, as the regulatory sea area is expected to increase further, it is expected that the frequency of switching cylinder oil will increase along with the switching of fuel oil during voyage. In order to simplify this complicated switching operation, it is desirable that a single cylinder oil that can be used for both high-sulfur fuel and low-sulfur fuel can be used as the cylinder oil.

  On the other hand, gasification of fuel is also being studied. When the fuel is a gas, although the amount of sulfur in the fuel is small, a cylinder oil having a base number of 40 mgKOH / g or more is preferable from the viewpoint of ensuring cleanliness, but in this case, the base number becomes excessive even at 40 mgKOH / g. . In order to stably operate a gas-fired engine, it is necessary to suppress the accumulation of excessive base components on the top land of the piston. Therefore, even when the gas is used as fuel, if there is no problem with the same cylinder oil as the liquid fuel, the complexity and cost of the supply side can be reduced.

  Many conventional cylinder oils have low-cost base oils with overbased sulfonate metal detergents as the main component to maintain corrosion wear resistance, but recently, salicylate, phenate or There have been developed various types of metal detergents such as composite detergents as main components and further containing extreme pressure agents and dispersants (Patent Documents 1 to 5).

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 has no problem with any sulfur amount fuel in addition to conventional performance such as heat resistance, cleanliness, wear resistance, etc. as a cylinder lubricant for a crosshead type diesel engine. An object of the present invention is to provide a cylinder lubricant for a crosshead type diesel engine in which the piston deposit amount is suppressed even when the base number is excessive.

  As a result of intensive studies to solve the above problems, the present inventors contain an ashless dispersant and a metallic detergent, and the product of the number average molecular weight, the blending amount, and the effective concentration of the ashless dispersant is a specific value or more. The present inventors have found that a cross-head type diesel engine cylinder lubricating oil composition in which the endothermic peak temperature of the metallic detergent is not more than a specific value can improve the above problems, and have completed the present invention.

That is, the present invention includes (A) a lubricating base oil containing (B) an ashless dispersant and (C) a metal-based detergent,
The (A) lubricating base oil has a kinematic viscosity at 100 ° C. of 4 to 50 mm ² / s and a kinematic viscosity at 100 ° C. of 4 mm ² / s or more and less than 17 mm ² / s. Comprising at least one of a base oil and a synthetic base oil and a mineral oil base oil and a synthetic oil base oil having a kinematic viscosity at 100 ° C. of 17 to 150 mm ² / s,
The (B) ashless dispersant is a bis-type or mono-type succinimide,
The product of the number average molecular weight, the blending amount and the effective concentration of the (B) ashless dispersant is 9000 or more,
The (C) metallic detergent is an overbased calcium salicylate or an overbased calcium sulfonate,
The (C) metal-based detergent is a cylinder lubricant composition for a crosshead type diesel engine having an endothermic peak temperature of 460 ° C. or less at a temperature rising rate of 50 ° C./min as measured by DSC. .

  Furthermore, the number average molecular weight of the ashless dispersant as described in (B) is 2500 or more, The cylinder lubricating oil composition for a crosshead type diesel engine.

  The present invention softens the ash content of the cylinder oil that accumulates on the piston top land and easily breaks down to suppress deposit accumulation on the land portion. This is a cylinder lubricating oil composition for a crosshead type diesel engine that can be used in sulfur fuel and gas-fired engines.

It is a photograph which shows the baked material (ash content) height.

  Hereinafter, the present invention will be described in detail. (A) Lubricating oil 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 oil system used for ordinary lubricating oil. Base oils and / or synthetic oil 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, GTL WAX (Gas Liquid Liquid) produced by one or more processes such as solvent dewaxing, catalytic dewaxing, hydrorefining, etc., or GTL WAX (Gas Liquid Liquid) produced by wax isomerized mineral oil, Fischer-Tropsch process, etc. is isomerized. Examples thereof include a lubricating base oil produced by a technique.

  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. The total aromatic content of the mineral base oil may be 0% by mass, but is preferably 1% by mass or more, more preferably 5% by mass or more, more preferably 10% by mass or more in terms of the solubility of the additive. More preferably, it is particularly 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 the sulfur content in mineral oil type base oil, 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.

Specific examples of synthetic base oil include polybutene or hydride thereof; poly α-olefin or hydride thereof having 8 to 14 carbon atoms represented by 1-octene oligomer, 1-decene oligomer, etc. Diesters such as ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate; trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexa Polyol esters such as noate and pentaerythritol pelargonate; copolymers of dicarboxylic acids such as dibutyl maleate and α-olefins having 2 to 30 carbon atoms; fragrances such as alkylnaphthalenes, alkylbenzenes and aromatic esters A group synthetic oil or a mixture thereof can be exemplified. Among these, the most preferable synthetic oil base oil is the oligomer having 8 to 14 carbon atoms called polyalphaolefin, and its kinematic viscosity at 100 ° C. is 4 to 150 mm ² / s.

  In the present invention, as the lubricating base oil (A), a mineral base oil, a synthetic base oil, or any mixture of two or more base oils selected from these can be used. Examples thereof include one or more mineral oil base oils, one or more synthetic oil base oils, a mixed oil of one or more mineral oil base oils and one or more synthetic oil base oils, and the like.

Kinematic viscosity at 100 ° C. of the lubricating base oil used is a 4~50mm ² / s, preferably 6~40mm ² / s, particularly preferably 8~35mm ² / s. When the kinematic viscosity at 100 ° C. of the lubricating base oil exceeds 50 mm ² / s, the low-temperature viscosity characteristic deteriorates, whereas when the kinematic viscosity is less than 4 mm ² / s, oil film formation at the lubrication site is caused. 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 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 150 mm ^2. / S of 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 oil base oils such as SAE 10-40 and synthetic oil base oils. it is preferably 5.6 mm ² / s or more, more preferably 9.3 mm ² / s or more, preferably 14 mm ² / s or less, and more preferably not more than 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 oil base oils and synthetic oil base oils such as SAE50 and Brightstock, and the kinematic viscosity is preferably 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. Furthermore, as the lubricating base oil having a kinematic viscosity at 100 ° C. of 50 to 150 mm ² / s, a synthetic base oil is equivalent.

  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 according to ASTM D5800.

  The viscosity index of the lubricating base oil to be used 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 from low temperature to high temperature can be obtained. It is. On the other hand, the upper limit of the viscosity index of the lubricating base oil is not particularly limited, and those having a viscosity index of about 135 to 180, such as normal paraffin, slack wax, GTL wax, or isoparaffin mineral oil obtained by isomerizing these, In addition, although those having a viscosity index of about 150 to 250 such as complex ester base oil and HVI-PAO base oil can be used, the viscosity index is 120 in terms of the solubility and storage stability of the additive. Or less, more preferably 110 or less.

  The cylinder lubricating oil composition for a crosshead type diesel engine of the present invention contains (B) an ashless dispersant (hereinafter also referred to as (B) component) as an essential component.

  As the component (B), any ashless dispersant used in lubricating oils can be used. For example, a linear or branched alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms in the molecule. And at least one nitrogen-containing compound or derivative thereof, a Mannich dispersant, or a modified product of alkenyl succinimide. In use, one kind or two or more kinds arbitrarily selected from these can be blended.

  When 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 lubricant base oil may be reduced, whereas when it exceeds 400, the lubricant composition of the present invention may be reduced. There is a risk that the low-temperature fluidity of the product will deteriorate. The alkyl group or alkenyl group may be linear or branched, and is preferably a branch derived from an olefin oligomer such as propylene, 1-butene, isobutylene, or a co-oligomer of ethylene and propylene. An alkyl group and a branched alkenyl group.

Examples of the component (B) include one or more compounds selected from the following components (B-1) to (B-3).
(B-1) A succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof,
(B-2) benzylamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof,
(B-3) Polyamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof.

As said (B-1) component, the compound shown by following formula (1) or (2) can be illustrated.

In the formula (1), R ¹ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and h represents an integer of 1 to 5, preferably 2 to 4.

On the other hand, in formula (2), R ² and R ³ each independently represent an alkyl group or 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 (B-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 in which succinic anhydride is added to both ends of the polyamine ( Although the so-called bis-type succinimide represented by 2) is included, any of these or a mixture thereof may be included in the composition of the present invention.

  There is no restriction | limiting in particular in the manufacturing method of the succinimide which is the said (B-1) component, 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. Here, examples of the polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

As said (B-2) component, the compound represented by following formula (3) can be illustrated.

In formula (3), R ⁴ represents an alkyl 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 the benzylamine which is the said (B-2) component, For example, after making polyolefin, such as a propylene oligomer, polybutene, or an ethylene-alpha-olefin copolymer, react with phenol to make alkylphenol, Examples thereof include a method in which formaldehyde and a polyamine such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine are reacted by a Mannich reaction.

As said (B-3) component, the compound represented by following formula (4) can be illustrated.
R ⁵ —NH— (CH ₂ CH ₂ NH) _k —H (4)

In the formula (4), R ⁵ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably 60 to 350 carbon atoms, and k represents an integer of 1 to 5, preferably 2 to 4.

  There is no restriction | limiting in particular in the manufacturing method of the polyamine which is the said (B-3) component, For example, after chlorinating polyolefin, such as a propylene oligomer, polybutene, or an ethylene-alpha-olefin copolymer, this is ammonia, ethylenediamine, diethylenetriamine. , A method of reacting polyamines such as triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine.

  Examples of the derivative of the nitrogen-containing compound exemplified as the component (B) include, for example, monocarboxylic acids such as fatty acids, oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid having 1 to 30 carbon atoms in the aforementioned nitrogen-containing compound. C2-30 polycarboxylic acids such as acids or their anhydrides, or ester compounds, alkylene oxides having 2-6 carbon atoms, hydroxy (poly) oxyalkylene carbonate, and the remaining amino group and / or Modified compounds by so-called oxygen-containing organic compounds, in which some or all of the imino groups are neutralized or amidated; one of the remaining amino groups and / or imino groups by reacting boric acid with the nitrogen-containing compounds described above A so-called boron-modified compound obtained by neutralizing a part or the whole or amidating it; by reacting phosphoric acid with the aforementioned nitrogen-containing compound, residual amino And / or a so-called phosphoric acid-modified compound obtained by neutralizing or amidating a part or all of the imino group; a sulfur-modified compound obtained by allowing a sulfur compound to act on the nitrogen-containing compound described above; and the nitrogen-containing compound described above. Examples thereof include modified compounds in which two or more kinds of modifications selected from oxygen organic compound modification, boron modification, phosphoric acid modification, and sulfur modification are combined. Among these derivatives, the boric acid-modified compound of alkenyl succinimide, particularly the boric acid-modified compound of bis-type alkenyl succinimide, can further improve the heat resistance when used in combination with the above-mentioned component (A). .

  The content ratio of the component (B) in the lubricating oil composition of the present invention is usually 0.005 to 0.4% by mass, preferably 0.01 to 0.2% by mass, as the amount of nitrogen, based on the total amount of the composition. More preferably, it is 0.01-0.1 mass%, Most preferably, it is 0.02-0.05 mass%. Further, when a boron-containing ashless dispersant is used as the component (B), 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, it is 0.7-0.9. The higher the B / N ratio is, the easier it is to improve the wear resistance and seizure resistance. Moreover, when using a boron containing ashless dispersant, the content rate does not have a restriction | limiting in particular, However, Preferably it is 0.001-0.1 mass% as a boron amount on the basis of the composition whole quantity, More preferably, it is 0.005. -0.05 mass%, Most preferably, it is 0.01-0.04 mass%.

  In the lubricating oil composition of the present invention, the component (B) preferably has a boron content of 0.5% by mass or more, more preferably 1.0% by mass or more, still more preferably 1.5% by mass or more, particularly preferably. It is most desirable to include 1.8% by mass of a boron-containing ashless dispersant, in particular, a bis-type boron-containing succinimide-based ashless dispersant. Here, the boron-containing ashless dispersant having a boron content of 0.5% by mass or more includes 10 to 90% by mass, preferably 30 to 70% by mass, for example, a diluent oil such as mineral oil or synthetic oil. The boron content usually means the boron content in a state including a diluent oil.

  The number average molecular weight (Mn) of the component (B) in the present invention is measured by removing the diluted oil from the sample by rubber membrane fractionation and analyzing it by GPC (Gel Permeation Chromatography).

The procedure for rubber membrane dialysis fractionation is as follows.
(I) Collect about 5 g of sample in the rubber film.
(Ii) The rubber film is bound with a thread, and the rubber film is placed in a cylindrical filter paper.
(Iii) Place in a Soxhlet extractor with cylindrical filter paper.
(Iv) Put 100 ml of petroleum ether in a flat flask, and install a Soxhlet extractor on it.
(V) The flat flask is heated in a water bath (70 ° C.), and the Soxhlet extractor is cooled with an attached cooler.
(Vi) Heat to reflux for 2 days.
(Vii) The dialysis residue in the rubber membrane is transferred to a beaker, and the rubber membrane deposit is washed into the beaker with petroleum ether. Petroleum ether is heated and removed with a water bath, and the rubber film residue is obtained.
(Viii) Petroleum ether in the flat flask portion is removed by heating with a water bath, and the rubber membrane dialyzed portion is obtained.

The analysis conditions for GPC are as follows.
Apparatus: Waters Alliance 2695
Column: Tosoh GMHHR-M
Mobile phase: tetrahydrofuran Sample solvent concentration: 1% by mass (solvent is tetrahydrofuran)
Temperature: 23 ° C
Flow rate: 1 ml / min
Sample volume: 100 μl
Detector: RI
Molecular weight: Polystyrene conversion

  In the present invention, the effective concentration of the ashless dispersant as the component (B) was determined from the result of the rubber membrane dialysis fraction described above. That is, the ratio of the mass remaining in the rubber film with respect to the amount of sample (about 5 g) collected as a sample first was taken as the effective concentration.

  In the present invention, it is necessary to blend (B) the ashless dispersant such that the product of its number average molecular weight (Mn), blending amount and effective concentration is 9000 or more, which is preferably 10,000 or more, More preferably, it is 12000 or more, More preferably, it is 15000 or more, Most preferably, it is 20000 or more, However, It is preferable that it is 50000 or less. If the product is less than 9000, the deposit intended in the present invention is not easily broken, not only the deposits increase, but also the adverse effect on wear increases. On the other hand, when the product exceeds 50000, the viscosity is too high, the fluidity is insufficient, and the deposit is increased.

  Here, the fragility of the deposit is measured by the height of the product obtained by firing the cylinder lubricating oil composition by TGA (Thermo Gravimetry Analyzer). Specifically, a cylinder lubricant composition is collected in a hermetic pan of a TGA (thermobalance), baked, and the baked product of the cylinder lubricant composition swelled like a cupcake from the hermetic pan as shown in FIG. Measure the height. The higher this height, the easier it is to break if it is formed as a deposit. Details are described in the Examples column.

  The number average molecular weight (Mn) of the (B) ashless dispersant in the present invention is preferably 2500 or more, more preferably 3000 or more, further preferably 4000 or more, and most preferably 5000 or more, but 10,000 or less. Preferably there is. When the number average molecular weight of the ashless dispersant is less than 2500, the deposit intended in the present invention is not easily broken, not only the deposits increase, but also the adverse effect on wear increases. On the other hand, when the number average molecular weight of the ashless dispersant exceeds 10,000, the viscosity is too high, the fluidity becomes insufficient, and the deposit increases.

  In the present invention, the blending amount and effective concentration of (B) the ashless dispersant are not particularly limited as long as the product of the number average molecular weight (Mn) of the ashless dispersant, the blending amount and the effective concentration is 9000 or more. However, the effective concentration of (B) ashless dispersant (ratio of the mass remaining in the rubber film to the amount of sample initially collected as a sample) is preferably in the range of 0.30 to 0.70, and (B) The concentration of the ash dispersant in the composition (the product of the blending amount and the effective concentration) is preferably in the range of 0.9 to 14% by mass based on the total amount of the lubricating oil composition.

  The cylinder lubricating oil composition for a crosshead type diesel engine of the present invention contains (C) a metal-based detergent (hereinafter sometimes referred to as (C) component) as an essential component.

  (C) As the metal detergent, any compound usually used for lubricating oils can be used, and examples thereof include sulfonate detergent, phenate detergent, salicylate detergent, and naphthenate detergent. . In use, these metal detergents can be used alone or in combination of two or more.

  Examples of the sulfonate detergent include alkali metal salts and alkaline earth metals of alkyl aromatic sulfonic acids obtained by sulfonating alkyl aromatic compounds having a weight average molecular weight of 400 to 1500, preferably 700 to 1300. A salt or a (over) basic salt thereof can be used. Examples of the alkali metal or alkaline earth metal include sodium, potassium, magnesium, barium, and calcium. Magnesium or calcium is preferable, and calcium is particularly preferable. Examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid. Examples of the petroleum sulfonic acid herein include those obtained by sulfonating an alkyl aromatic compound of a lubricating oil fraction of mineral oil, and so-called mahoganic acid that is by-produced during white oil production. As the synthetic sulfonic acid, for example, an alkylbenzene having a linear or branched alkyl group, which is produced as a by-product from an alkylbenzene production plant that is a raw material of a detergent or obtained by alkylating a polyolefin with benzene, is used. A sulfonated one or a sulfonated alkylnaphthalene such as dinonylnaphthalene is used. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, but usually fuming sulfuric acid or sulfuric anhydride is used.

As said phenate type | system | group detergent, the alkyl metal sulfide alkali metal salt, alkaline-earth metal salt, or its (over) basic salt which has a structure shown by following formula (5) can be used. Examples of the alkali metal or alkaline earth metal include sodium, potassium, magnesium, barium, and calcium. Magnesium or calcium is preferable, and calcium is particularly preferable.

In the formula (5), R ⁶ represents a linear or branched, saturated or unsaturated alkyl group or alkenyl group having ⁶ to 21 carbon atoms, m is a degree of polymerization, and is an integer of 1 to 10, and S is sulfur. Element and x show the integer of 1-3.

  Carbon number of the alkyl group and alkenyl group in Formula (5) becomes like this. Preferably it is 9-18, More preferably, it is 9-15. If the carbon number is less than 6, the solubility in the base oil may be inferior. On the other hand, if the carbon number exceeds 21, the production is difficult and the heat resistance may be inferior.

  Among phenate-type metal detergents, those containing an alkylphenol sulfide metal salt having a polymerization degree m of 4 or more, particularly m of 4 to 5 shown in formula (5) are preferable because of excellent heat resistance.

  Examples of the salicylate detergent include an alkali metal having one hydrocarbon group having 1 to 19 carbon atoms, an alkaline earth metal salicylate or a (over) basic salt thereof, and a hydrocarbon group having 20 to 40 carbon atoms. Alkali metal having one, alkaline earth metal salicylate or (over) basic salt thereof, alkali metal having two or more hydrocarbon groups having 1 to 40 carbon atoms, alkaline earth metal salicylate or (over) base thereof Salt. These hydrocarbon groups may be the same or different. In these, it is desirable to use the alkali metal, alkaline-earth metal salicylate, or its (over) basic salt which has one C8-19 hydrocarbon group at the point which is excellent in low-temperature fluidity | liquidity. Examples of the alkali metal or alkaline earth metal include sodium, potassium, magnesium, barium, and calcium. Magnesium and / or calcium are preferable, and calcium is particularly preferably used.

  The base number of component (C) is preferably in the range of 50 to 500 mgKOH / g, more preferably in the range of 100 to 450 mgKOH / g, and still more preferably in the range of 120 to 400 mgKOH / g. When the base number is less than 50 mgKOH / g, the corrosion wear may increase. On the other hand, when it exceeds 500 mgKOH / g, there may be a problem in solubility.

  The metal ratio of the component (C) is not particularly limited, but the lower limit is preferably 1 or more, more preferably 2 or more, particularly preferably 2.5 or more, and the upper limit is preferably 20 or less, more preferably 19 or less, particularly preferably. Is preferably 18 or less. The metal ratio here is represented by the valence of the metal element in the component (C) × metal element content (mol%) / soap group content (mol%). Further, the metal element means calcium, magnesium and the like, and the soap group means a sulfonic acid group, a phenol group, a salicylic acid group and the like.

  In the lubricating oil composition of the present invention, the component (C) can be used alone, but it is preferable to use two or more kinds in combination. When used in combination, in particular, (1) overbased Ca phenate / overbased Ca sulfonate, (2) overbased Ca phenate / overbased Ca salicylate, (3) overbased Ca phenate / overbased Ca sulfonate / A combination of overbased Ca salicylate is preferred.

  A preferred ratio of (1) overbased Ca phenate / overbased Ca sulfonate or (2) overbased Ca phenate / overbased Ca salicylate is 0.1 or more in terms of the weight ratio of the additive. 2 or more is more preferable, and 0.3 or more is most preferable. This is because the heat resistance is inferior when the ratio is less than 0.1. The ratio is preferably 9 or less, more preferably 7 or less, and most preferably 5 or less. This is because when the ratio exceeds 9, the height in the TGA firing test is not sufficient, and the deposit on the piston top land is not sufficiently reduced.

  (3) In the case of overbased Ca phenate / overbased Ca sulfonate / overbased Ca salicylate, the sum of the overbased Ca sulfonate and the overbased Ca salicylate with respect to the overbased Ca phenate is the above ratio. Is preferred. In this case, although there is no restriction | limiting in the weight ratio of the compounding quantity of overbased Ca sulfonate / overbased Ca salicylate, 0.1 or more are preferable, 0.2 or more are further more preferable, and 0.3 or more are the most preferable. This is because if the weight ratio is less than 0.1, the deposit may increase conversely in a state far exceeding 300 ° C. The weight ratio is preferably 9 or less, more preferably 7 or less, and most preferably 5 or less. When the weight ratio exceeds 9, the cleanliness deteriorates.

  In the lubricating oil composition of the present invention, the content ratio of the component (C) is preferably 3 to 30% by mass, more preferably 6 to 25% by mass, and particularly preferably 8 to 20% by mass based on the total amount of the composition. is there. When the content ratio of the component (C) is less than 3% by mass, the required cleanliness and acid neutralization may not be obtained. On the other hand, when the content exceeds 30% by mass, the excess metal component is a piston. There is a risk of accumulation.

  In the lubricating oil composition of the present invention, the metal content based on the component (C) is preferably 0.35 to 3.6% by mass, more preferably 1.0 to 2.9, based on the total amount of the composition. % By mass, particularly preferably 1.4 to 2.7% by mass. When the content ratio of the metal component based on the component (C) is less than 0.7% by mass, the necessary cleanliness and acid neutralization may not be obtained. On the other hand, when the content exceeds 3.6% by mass In this case, excessive ash may accumulate on the piston top land, causing bore polishing or scuffing of the liner.

  The component (C) of the present invention needs to have an endothermic peak temperature measured by DSC (Differential Scanning Calorimeter) of 460 ° C. or less.

The DSC measurement conditions are as follows.
Equipment: TA Instruments DSC2920
Sample collection bread: hermetic bread Sample collection amount: 30 mg
Atmosphere: Nitrogen (Flow rate: 50 ml / min)
Temperature increase rate: 50 ° C / min
Endothermic peak temperature: endothermic peak temperature after the diluent oil of the additive has evaporated

  When the endothermic peak temperature exceeds 460 ° C., the effect of softening the deposit cannot be obtained sufficiently. Of course, those having no endothermic peak between the endothermic peak accompanying evaporation of the diluent oil and 460 ° C. have no effect of softening the deposit. On the other hand, the lower limit of the endothermic peak temperature of (C) the metallic detergent is not particularly limited, but is preferably 350 ° C. or higher. Below this, the compound becomes unstable and the heat resistance may be insufficient.

  The lubricating oil composition of the present invention preferably contains a sulfur-based extreme pressure agent as the other component. Preferred examples of the sulfur-based extreme pressure agent include dihydrocarbyl polysulfide, sulfurized fatty acid, sulfurized olefin, sulfurized ester, sulfurized fat, sulfurized mineral oil, thiazole compound, thiadiazole compound, and alkylthiocarbamate compound.

  In addition, the lubricating oil composition of the present invention preferably contains an organic molybdenum compound. Examples of the organic molybdenum compound include organic molybdenum compounds containing sulfur such as molybdenum dithiophosphate and molybdenum dithiocarbamate (MoDTC); molybdenum compounds (eg, molybdenum oxide such as molybdenum dioxide and molybdenum trioxide; orthomolybdic acid, para Molybdic acid such as molybdic acid and (poly) sulfurized molybdic acid; molybdate such as metal salt and ammonium salt of molybdic acid; molybdenum sulfide such as molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, and polysulfide molybdenum; Metal salts or amine salts of molybdic acid, sulfurized molybdic acid, molybdenum halides such as molybdenum chloride) and sulfur-containing organic compounds [eg, alkyl (thio) xanthate, thiadiazole, mercaptothiadiazole Complex with thiocarbonate, tetrahydrocarbylthiuram disulfide, bis (di (thio) hydrocarbyldithiophosphonate) disulfide, organic (poly) sulfide, sulfide ester] or other organic compounds; or the above molybdenum sulfide, molybdenum sulfide A complex of a sulfur-containing molybdenum compound such as an acid and an alkenyl succinimide can be given.

  Furthermore, the lubricating oil composition of the present invention preferably contains zinc dithiophosphate (ZnDTP) (hereinafter sometimes referred to as component (E)) as an antiwear agent. Examples of the zinc dithiophosphate include 3 to 18 carbon atoms such as zinc dipropyldithiophosphate, zinc dibutyldithiophosphate, zinc dipentyldithiophosphate, zinc dihexyldithiophosphate, zinc diheptyldithiophosphate, or zinc dioctyldithiophosphate. Is a dialkyldithiophosphate zinc having a linear or branched (primary, secondary or tertiary, preferably primary or secondary) alkyl group having 3 to 10 carbon atoms; zinc diphenyldithiophosphate Or a di ((alkyl) aryl) dithiophosphate zinc having an aryl group or an alkylaryl group having 6 to 18 carbon atoms, preferably 6 to 10 carbon atoms, such as zinc ditolyl dithiophosphate, or a mixture of two or more thereof. Can be mentioned.

  The lubricating oil composition of the present invention is generally 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 components. Optional additives can be further included. Examples of such additives include antioxidants, ashless friction modifiers, corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, antifoaming agents, and colorants.

  Examples of the antioxidant include ashless antioxidants such as phenols and amines; and metal antioxidants such as copper and molybdenum. The ratio in the case of containing these is 0.1-5 mass% normally on the composition whole quantity basis.

  Examples of the ashless friction modifier include fatty acid esters, aliphatic amines, and fatty acid amides. The ratio in the case of containing these is 0.1-5 mass% normally on the composition whole quantity basis.

  Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiadiazole, and 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, or polyoxyethylene alkyl naphthyl ether.

  Examples of the metal deactivator include imidazoline, pyrimidine derivatives, alkylthiadiazole, mercaptobenzothiazole, benzotriazole or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5- Bisdialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, or β- (o-carboxybenzylthio) propiononitrile.

Examples of the antifoaming agent include silicone oils and alkenyl succinic acid derivatives having a kinematic viscosity at 25 ° C. of less than 0.1 to 100 mm ² / s.

  When these additives are contained in the lubricating oil composition of the present invention, the content is usually 0.005 to 5% by mass based on the total amount of the composition, and usually 0.0005 to 1% by mass for the antifoaming agent. It is chosen from the range.

  The cylinder lubricating oil composition for a crosshead type diesel engine of the present invention preferably has a base number of 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, still more preferably 25 mgKOH / g or more, particularly preferably 40 mgKOH. / G or more, preferably 100 mgKOH / g or less, more preferably 85 mgKOH / g or less, and even more preferably 75 mgKOH / g or less. When the base number is less than 10 mgKOH / g, the piston cleanliness is insufficient. On the other hand, when the base number exceeds 100 mgKOH / g, the excessive base number, that is, the metal carbonate forms a deposit and causes wear and piston ring sticking.

  The base number when using both high sulfur fuel and low sulfur fuel is preferably 50 mgKOH / g or more, more preferably 60 mgKOH / g or more, and even more preferably 70 mgKOH / g or more. When the base number is less than 50 mgKOH / g, when high-sulfur fuel is used, the neutralizing ability of the generated acidic substance is not sufficient, and corrosion wear cannot be suppressed. The upper limit in this case is as described above.

  When only low sulfur fuel or gas fuel is used, the base number is preferably 60 mgKOH / g or less, more preferably 50 mgKOH / g or less, still more preferably 45 mgKOH / g or less. When the base number exceeds 60 mgKOH / g, when low-sulfur fuel or gas fuel is used, there is a high possibility that abrasion or piston ring sticking occurs due to the formation of an excess base number, that is, deposit due to metal carbonate. The lower limit in this case is as described above.

  Here, the high sulfur fuel means a fuel containing 3.5% by mass or more of the sulfur content, and the low sulfur fuel means a fuel having a sulfur content of less than 1.0% by mass. A fuel having a sulfur content of 1.0% by mass or more and less than 3.5% by mass can be handled in either a high sulfur fuel or a low sulfur fuel. In addition, the sulfur content of gas is 0.1 mass% or less.

  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 1-14, Comparative Examples 1-8)
A lubricating oil composition having the formulation shown in Table 1 was prepared, and as described above, the fragility of the formed deposit was measured by TGA. The test conditions are as follows.
Equipment: TA Instruments TGA2950
Sample collection bread: hermetic bread Sample collection amount: 30 mg
Atmosphere: Nitrogen (Flow rate: 50 ml / min)
Temperature increase rate: 50 ° C / min
Deposit fragility: ash content height after holding from 30 ° C. after raising temperature from room temperature to 600 ° C. FIG. 1 shows an example.

In addition, a WD300 engine test manufactured by Ricardo Co., Ltd. was performed on the prepared lubricating oil composition under the following conditions.
Equipment: WD300 engine manufactured by Ricardo (number of cylinders: 1, displacement: 2.2 L, piston bore: 135 mm)
Axial mean effective pressure: 20 bar
Rotation speed: 1200rpm
Fuel: Light oil (Sulfur content less than 10ppm)
Cooling water outlet temperature: 85 ° C
Lubricating oil temperature: 80 ° C
Piston Topland Evaluation Method: Merit score of the Petroleum Institute Method (JPI-5S-15) (The higher the score, the less the deposit)

The base oil: base oil ratio was changed to 44-69 parts by mass of solvent refined base oil SAE30 and 31-56 parts by mass of bright stock, and the kinematic viscosity (100 ° C.) of the lubricating oil composition was 20.0-21.0 mm. adjusted to ² / s * solvent refined base oil SAE 30: kinematic viscosity ^{(40 ℃) 94.33mm 2 / s} , kinematic viscosity (100 ℃) 10.79mm ² / s
** Bright stock: kinematic viscosity (40 ° C.) 466.6 mm ² / s, kinematic viscosity (100 ° C.) 31.57 mm ² / s

Ashless dispersant 1: polybutenyl succinimide, Mn 2390 (effective concentration 40% by mass, ratio of mass remaining in rubber film to collected sample amount = 0.4), endothermic peak temperature at DSC 442 ° C.
Ashless dispersant 2: polybutenyl succinimide, Mn 2660 (effective concentration 50 mass%, ratio of mass remaining in rubber film to collected sample amount = 0.5), endothermic peak temperature at DSC 447 ° C.
Ashless dispersant 3: polybutenyl succinimide, Mn 3180 (effective concentration 60 mass%, ratio of mass remaining in rubber film to collected sample amount = 0.6), endothermic peak temperature at DSC 456 ° C.
Ashless dispersant 4: Polybutenyl succinimide, Mn 4460 (effective concentration 50 mass%, ratio of mass remaining in rubber film to collected sample amount = 0.5), endothermic peak temperature 442 ° C. in DSC
Ashless dispersant 5: polybutenyl succinimide, Mn 4770 (effective concentration 60 mass%, ratio of mass remaining in rubber film to collected sample amount = 0.6), endothermic peak temperature at DSC 450 ° C.
Ashless dispersant 6: polybutenyl succinimide, Mn 7630 (effective concentration 45% by mass, ratio of mass remaining in rubber film to collected sample amount = 0.45), endothermic peak temperature at DSC 453 ° C.

Metal detergent 1: Overbased calcium salicylate, base number 320 mgKOH / g, endothermic peak temperature in DSC 403 ° C.
Metal detergent 2: Overbased calcium sulfonate, base number 400 mgKOH / g, endothermic peak temperature at DSC 449 ° C.
Metal detergent 3: Overbased calcium sulfonate, base number 400 mgKOH / g, endothermic peak temperature in DSC 470 ° C.
Metal detergent 4: Overbased calcium sulfonate, base number 400 mgKOH / g, endothermic peak temperature at DSC 481 ° C.
Metal detergent 5: Overbased calcium sulfonate, base number 400 mgKOH / g, endothermic peak temperature in DSC 498 ° C.
Metal detergent 6: Overbased calcium sulfonate, base number 400 mgKOH / g, endothermic peak temperature at DSC 512 ° C.
Metal detergent 7: Overbased calcium phenate, base number 150 mgKOH / g, endothermic peak temperature at DSC 484 ° C.

  As shown in Table 1, the height of the ash has a very good correlation with the piston top land rating according to the Ricardo WD300 engine test. That is, when the height of the ash exceeds 2 mm, the score of the deposit exceeds 3.5, which means that there is little adhesion of the deposit.

  The cylinder lubricating oil composition of the example has a high ash content and a high piston top land rating, whereas the product of the number average molecular weight, blending amount and effective concentration of the ashless dispersant is less than 9000. The cylinder lubricating oil compositions of Examples 2 to 4 and the cylinder lubricating oil compositions of Comparative Examples 5 to 8 that do not contain a metal detergent having an endothermic peak temperature of 460 ° C. or lower have a low ash content, and the piston top land The score of was also low.

Claims (2)

(A) A lubricant base oil contains (B) an ashless dispersant and (C) a metal detergent,
The (A) lubricating base oil has a kinematic viscosity at 100 ° C. of 4 to 50 mm ² / s and a kinematic viscosity at 100 ° C. of 4 mm ² / s or more and less than 17 mm ² / s. Comprising at least one of a base oil and a synthetic base oil and a mineral oil base oil and a synthetic oil base oil having a kinematic viscosity at 100 ° C. of 17 to 150 mm ² / s,
The (B) ashless dispersant is a bis-type or mono-type succinimide,
The product of the number average molecular weight, the blending amount and the effective concentration of the (B) ashless dispersant is 9000 or more,
The (C) metallic detergent is an overbased calcium salicylate or an overbased calcium sulfonate,
(C) The endothermic peak temperature at a heating rate of 50 ° C./min as measured by DSC is not more than 460 ° C. (C) The cylinder lubricant composition for a crosshead type diesel engine, characterized in that   The cylinder lubricating oil composition for a crosshead type diesel engine according to claim 1, wherein the (B) ashless dispersant has a number average molecular weight of 2500 or more.