CN107429190A - Lubricating oil composition for four-stroke cycle engine - Google Patents

Abstract

The lubricating oil composition for a four-stroke cycle engine comprises a base oil (A) and 0.5-10 mass% of a polyolefin (B), wherein the polyolefin (B) has at least a structural unit derived from isobutene and has a number average molecular weight of 500-10,000, and the lubricating oil composition has a sulfated ash content of 0.3-1.2 mass%.

Description

Lubricating oil composition for four-stroke cycle engine

technical field

The present invention relates to a lubricating oil composition for a four-stroke cycle engine, and relates to a lubricating oil composition that can be suitably used for a four-stroke cycle engine that operates continuously at a high load in, for example, marine or stationary power generation equipment.

Background technique

Engine oils used in gas-fired cogeneration systems and power generation equipment require high-viscosity lubricants such as SAE J300#40 in order to cope with high loads, and as base oils, even neutral oils (such as 500N mineral oil) are sometimes not available full viscosity. Therefore, in the past, high-viscosity base materials such as bright stock and ethylene-propylene copolymer (OCP) were sometimes blended.

In addition, conventionally, it is known, for example, as disclosed in Patent Document 1, that for lubricating oil compositions used in marine diesel engines and power generation engines, a Fischer-Tropsch-derived oil having a kinematic viscosity of 6 to 10 mm ² /s at Lubricant-fuel compatibility can be improved by adding a specified tackifier to the base oil of the FT method (FT origin). Here, as the thickener, one selected from FT-derived base oils, bright stocks, deasphalted cylinder oils, polyisobutylenes, and mixtures thereof having a kinematic viscosity at 100°C in the range of 15 to 30 mm ² /s can be used. Tackifier.

Furthermore, Patent Document 2 also discloses that, in lubricating oil compositions used in internal combustion engines such as gasoline engines and diesel engines, by blending 0.001 to 1% by weight of lubricating base oil, the weight average molecular weight of 500,000 to 1,000 Wan's polybutene and/or polyisobutylene can improve engine detergency.

It should be noted that, in recent years, for four-stroke cycle engines, in order to improve engine efficiency, the compression ratio and turbocharging pressure have been increased, and the combustion temperature and pressure of the engine tend to be increased accordingly. When the engine is operated at high temperature and high pressure, the lubricating oil deteriorates, and dirt tends to be generated on the lower side of the piston, the ring groove, and the land portion. Therefore, lubricating oils for four-stroke cycle engines are sometimes required to have high piston cleanliness. For example, marine or stationary power generation equipment and cogeneration systems are increasingly required to operate at high load rates for a long period of time.

prior art literature

patent documents

Patent Document 1: Japanese PCT Publication No. 2012-511608

Patent Document 2: Japanese Unexamined Patent Publication No. 2007-246771.

Contents of the invention

The problem to be solved by the invention

Conventional lubricating oils used in gas-fired cogeneration systems and engines for power generation equipment may be sludged at high temperatures when they are mixed with high-viscosity substrates such as bright stock, OCP, and thickeners described above. The generation of sludge sometimes leads to deterioration of piston detergency. Therefore, even though it is optimized to incorporate a highly heat-resistant detergent, dispersant, or antioxidant, there is a limit to suppressing the generation of sludge or improving piston detergency with these additives.

Furthermore, as disclosed in Patent Document 2, even if polybutene and/or polyisobutylene having a high molecular weight is blended in a proportion of 1% by mass or less, sludge formation cannot be sufficiently prevented. In addition, the effect of improving detergency is also limited.

In addition, for example, when increasing the amount of a metal-based detergent or the like to improve piston detergency, the metal component adheres to engine components, which may cause knocking. Therefore, in gas-fired cogeneration systems and engines for power generation equipment, manual cleaning is sometimes necessary to remove metal components adhering to engine parts and dirt on pistons, for example, when changing engine oil.

Furthermore, in recent years, turbocharging pressure has been gradually increased in order to improve engine efficiency. In turbochargers, there are concerns about carbon deposits (coking) due to deterioration of lubricating oil, damage to turbochargers, and the like. Therefore, it is required to suppress turbo coking in lubricating oils used in engines equipped with turbochargers. In addition, engine oils for gas-fired cogeneration systems and power generation equipment may require long drain intervals.

The present invention has been made in view of the above-mentioned actual situation, and the object of the present invention is to provide a four-stroke cycle engine that can suppress the generation of sludge under high-temperature operation and can improve various performances even if a high-viscosity base material is blended. lubricating oil composition.

Specifically, the object of the present invention in the first aspect is to provide a high-viscosity base material that can suppress the generation of sludge under high-temperature operation and improve piston cleaning performance so that cleaning operations are not performed frequently. A lubricating oil composition for a four-stroke cycle engine capable of preventing failures such as knocking.

Furthermore, the object of the present invention in the second aspect is to provide a high-viscosity base material that can suppress the generation of sludge under high-temperature operation, and has improved turbine coking resistance so that it can be used even in severe environments. A lubricating oil composition for a four-stroke cycle engine that also has long oil drain properties is used.

means to solve the problem

The inventors of the present invention conducted intensive studies to solve the above-mentioned problems, and as a result, found that by blending a polyolefin having a specific molecular weight and containing a structural unit derived from isobutylene in a predetermined amount, and at the same time making the amount of sulfated ash in the lubricating oil composition predetermined amount, the above-mentioned problems can be solved, and the present invention has been completed. The present invention provides the following lubricating oil composition for a four-stroke cycle engine.

A lubricating oil composition for a four-stroke cycle engine, comprising a base oil (A) and 0.5 to 10% by mass of a polyolefin (B), the polyolefin (B) having at least a structural unit derived from isobutylene and a number average molecular weight is 500 to 10,000, and the sulfated ash content of the lubricating oil composition is 0.3 to 1.2% by mass.

In addition, the present invention also provides a lubricating method, using the lubricating oil composition for a four-stroke cycle engine to lubricate between various components in a four-stroke cycle engine.

Furthermore, the present invention also provides a method for producing a lubricating oil composition for a four-stroke cycle engine described below.

A method for producing a lubricating oil composition for a four-stroke cycle engine, comprising adding 0.5 to 10% by mass of polyolefin (B) to the base oil (A) based on the total amount of the lubricating oil composition, and adjusting so that sulfuric acid The ash content is 0.3 to 1.2% by mass to obtain a lubricating oil composition for a four-stroke cycle engine, wherein the polyolefin (B) has at least a structural unit derived from isobutylene and has a number average molecular weight of 500 to 10,000.

In addition, the inventors of the present invention have made intensive studies to solve the problem of the present invention in the above-mentioned first aspect. The sulfated ash in the lubricating oil composition can solve this problem, and the present invention in the first aspect described below has been completed. The present invention in the first aspect provides the following lubricating oil composition for a four-stroke cycle engine.

A lubricating oil composition for a four-stroke cycle engine, comprising a base oil (A) and 0.5 to 10% by mass of a polyolefin (B), the polyolefin (B) having at least a structural unit derived from isobutylene and a number average molecular weight is 500 to 10,000, and the sulfated ash content of the lubricating oil composition is 0.3 to 0.7% by mass.

In addition, the present invention according to the first aspect also provides a lubricating method for lubricating between various parts in a four-stroke cycle engine with the above-mentioned lubricating oil composition for a four-stroke cycle engine.

Furthermore, the present invention in the first aspect also provides a method for producing a lubricating oil composition for a four-stroke cycle engine described below.

A method for producing a lubricating oil composition for a four-stroke cycle engine, comprising adding 0.5 to 10% by mass of polyolefin (B) to the base oil (A) based on the total amount of the lubricating oil composition, and adjusting so that sulfuric acid The ash content is 0.3-0.7% by mass to obtain a lubricating oil composition for a four-stroke cycle engine. The polyolefin (B) has at least a structural unit derived from isobutylene and has a number-average molecular weight of 500-10,000.

In addition, the inventors of the present invention have made intensive studies to solve the problem of the present invention in the above-mentioned second aspect. The sulfated ash in the lubricating oil composition is contained in a predetermined amount, and this problem can be solved, and the present invention in the second aspect has been completed. The present invention in the second aspect provides the following lubricating oil composition for a four-stroke cycle engine.

A lubricating oil composition for a four-stroke cycle engine, comprising a base oil (A) and 0.5 to 10% by mass of a polyolefin (B), the polyolefin (B) having at least a structural unit derived from isobutylene and a number average molecular weight is 500 to 10,000, and the sulfated ash content of the lubricating oil composition is greater than 0.7% by mass and not more than 1.2% by mass.

Furthermore, the present invention in the second aspect provides a lubricating method for lubricating between components in a four-stroke cycle engine with the above-mentioned lubricating oil composition for a four-stroke cycle engine.

Furthermore, the present invention in the second aspect also provides a method for producing a lubricating oil composition for a four-stroke cycle engine described below.

A method for producing a lubricating oil composition for a four-stroke cycle engine, comprising adding 0.5 to 10% by mass of polyolefin (B) to the base oil (A) based on the total amount of the lubricating oil composition, and adjusting so that sulfuric acid The ash content is more than 0.7% by mass and not more than 1.2% by mass to obtain a lubricating oil composition for a four-stroke cycle engine, wherein the polyolefin (B) has at least a structural unit derived from isobutylene and has a number average molecular weight of 500 to 10,000.

The effect of the invention

In the present invention, even if a high-viscosity substrate is blended, it is possible to suppress the generation of sludge under high-temperature operation and to improve various performances.

More specifically, in the first aspect, even if a high-viscosity base material is used, the generation of sludge under high-temperature operation can be suppressed, and the cleaning performance of the piston can be improved so that knocking can be prevented even without frequent cleaning operations. A lubricating oil composition for a four-stroke cycle engine with such failures.

Furthermore, in the second aspect, even if a high-viscosity base material is used, the generation of sludge under high-temperature operation can be suppressed, and the anti-coking of the turbine is improved, so that it has long oil change even when used in a severe environment. Lubricating oil compositions for periodic four-stroke cycle engines.

detailed description

The lubricating oil composition for a four-stroke cycle engine according to the embodiment of the present invention comprises a base oil (A) and 0.5 to 10% by mass of a polyolefin (B) having at least a structure derived from isobutylene unit, and the number average molecular weight is 500-10,000, and the sulfated ash content of the lubricating oil composition is 0.3-1.2% by mass.

Hereinafter, embodiments of the present invention will be described in more detail. In addition, in the following description, the embodiment corresponding to the said 1st aspect is demonstrated as 1st embodiment, and the embodiment corresponding to the 2nd aspect is demonstrated as 2nd embodiment.

The lubricating oil composition for a four-stroke cycle engine according to the first embodiment contains at least a base oil (A) and a polyolefin (B), and has a sulfated ash content of 0.3 to 0.7% by mass.

In addition, the lubricating oil composition for a four-stroke cycle engine of the second embodiment contains at least a base oil (A) and a polyolefin (B), and has a sulfated ash content of more than 0.7 mass % and 1.2 mass % or less.

Hereinafter, unless otherwise specified, the lubricating oil compositions for four-stroke cycle engines of the first and second embodiments (hereinafter, may be simply referred to as "lubricating oil composition") will be collectively described in detail.

[base oil]

The base oil (A) is appropriately selected from mineral oils and synthetic oils.

Examples of the mineral oil include paraffin-based mineral oil, naphthene-based mineral oil, and intermediate-based mineral oil. distillate, and the obtained lubricating oil fraction is subjected to solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, etc., to refine mineral oil, etc., more specifically , Light neutral oil, medium neutral oil, heavy neutral oil, etc. are mentioned.

In addition, as the mineral oil, it may be a mineral oil classified into any one of Type 1, Type 2, and Type 3 in the base oil category of API (American Petroleum Institute). From the viewpoint of suppressing sludge generation, it is preferable Mineral oil classified as Class 2 or Class 3. It should be noted that the base oil classified as Group 1 has a saturation content of less than 90% and/or a sulfur content of more than 0.03%, and a viscosity index of 80 or more and less than 120. In addition, the base oil classified as Class 2 has a saturation content of 90% or more and a sulfur content of 0.03% or less, and a viscosity index of 80 or more and less than 120. Furthermore, the base oil classified into Class 3 has a saturation content of 90% or more, a sulfur content of 0.03% or less, and a viscosity index of 120 or more.

In addition, the sulfur component is a value measured according to JIS K 2541, and the saturated component is a value measured according to ASTM D 2007. Furthermore, the viscosity index is a value measured according to JIS K 2283.

Examples of synthetic oils include poly-α-olefins (PAO), which are polymers of α-olefins with 6 to 16 carbon atoms; various esters such as polyol esters, dibasic acid esters, and phosphoric acid esters; Various ethers such as ethers; polyalkylene glycols, alkylbenzenes, alkylnaphthalenes, base oils produced by isomerizing GTL WAX, etc.

As the base oil (A), one kind of mineral oil may be used alone, or two or more kinds may be used in combination. In addition, one kind of synthetic oil may be used alone, or two or more kinds may be used in combination. Furthermore, one or more mineral oils and one or more synthetic oils may be used in combination.

In addition, the base oil (A) is the main component of the lubricating oil composition, and is usually contained at 50% by mass or more, preferably 60 to 97% by mass, more preferably 70 to 95% by mass, based on the total amount of the lubricating oil composition .

The viscosity of the base oil (A) is not particularly limited, but the kinematic viscosity at 100°C is preferably in the range of 2 to 25 mm ² /s, more preferably in the range of 4 to 20 mm ² /s, still more preferably in the range of 5 to 15 mm ² /s range. The lubricating oil composition of the present embodiment can be suitably used for a four-stroke cycle engine operating at a high load, especially a gas cogeneration, by making the kinematic viscosity of the base oil (A) high in this way.

[Polyolefin (B)]

As the polyolefin (B), a polyolefin (B) having at least a structural unit derived from isobutylene and having a number average molecular weight of 500 to 10,000 is used. When a lubricating oil composition contains (B) component whose number average molecular weight is 500 or more like this, the viscosity of a lubricating oil composition can be raised.

In the first embodiment, the component (B) contains a structural unit derived from isobutylene and has a number-average molecular weight of 10,000 or less, which is a relatively low value. Therefore, it is possible to suppress the generation of sludge in a high-temperature environment (for example, 200° C. or higher), It is also possible to maintain good detergency (for example, piston detergency). In addition, in conjunction with low sulfuric acid ash content, it is possible to suppress the adhesion of metal components and dirt in engine parts. Therefore, failures such as knocking can be prevented even if engine parts are cleaned infrequently.

In the second embodiment, the component (B) contains a structural unit derived from isobutylene and has a number average molecular weight as low as 10,000 or less. Therefore, generation of sludge in a high-temperature environment (for example, 200° C. or higher) can be suppressed. In addition, as will be described later, by making the sulfated ash content within a predetermined range, oil deterioration at high temperatures is also suppressed, and it is easy to prevent the occurrence of turbo coking.

In 1st and 2nd embodiment, it is preferable that the number average molecular weight of (B) component is 600-6000. By setting the number average molecular weight to be 600 or more, the viscosity of the lubricating oil composition can be further easily increased by the (B) component. Moreover, by making it 6000 or less, it becomes easy to prevent generation|occurrence|production of sludge more effectively. And, for example, in the first embodiment, it is easy to make the detergency good. From these viewpoints, it is more preferable that the number average molecular weight of (B) component is 700-3000.

As the olefin other than isobutene in the component (B), for example, an olefin having 2 to 20 carbon atoms can be used, and as a specific example, ethylene, propylene, 1-butene, 2-butene, 3-methyl Base-1-butene, 4-phenyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl- 1-pentene, 3,4-dimethyl-1-pentene, 4,4-dimethyl-1-pentene, 1-hexene, 4-methyl-1-hexene, 5-methyl -1-hexene, 6-phenyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-pentadecene, 1-decacene Hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, etc. Of these, 1-butene is preferred.

The polyolefin preferably contains 50 to 100 mol%, more preferably 70 to 100 mol%, and still more preferably 80 to 100 mol%, of isobutylene-derived structural units. In this way, if the amount of structural units derived from isobutylene increases, the generation of sludge can be further suppressed. Furthermore, in the first embodiment, it is easy to improve the detergency, and in the second embodiment, it is easy to improve the turbo-coking resistance.

In addition, the polyolefin (B) is preferably obtained by polymerizing various butenes from the viewpoint of suppressing the generation of sludge, improving the detergency in the first embodiment, and improving the turbo-coking resistance in the second embodiment. Among the obtained polybutenes, polyisobutylene is more preferable. It should be noted that polyisobutene in this specification includes not only polyisobutene whose structural units are all derived from isobutylene, but also includes a part (20 mol % or less, preferably 10 mol % or less) of structural units derived from 1-butene, etc. Polyisobutene which is a structural unit of other butenes.

The component (B) may be a hydrogenated product, for example, a hydrogenated product of polybutene or a hydrogenated product of polyisobutylene, preferably unhydrogenated, that is, the above-mentioned polybutene and polyisobutylene are preferably unhydrogenated. In the first and second embodiments, it is easier to suppress generation of sludge and the like when hydrogenation is not performed.

Content of (B) component in each embodiment is 0.5-10 mass % based on a composition whole quantity. By making content of (B) component 0.5 mass % or more, the viscosity of a lubricating oil composition can be raised suitably. Moreover, the generation|occurrence|production of sludge and the fall of dispersibility can be prevented by making content of (B) component into 10 mass % or less. From these viewpoints, in the first embodiment, the content of the component (B) is more preferably 1.0 to 8.0% by mass, and still more preferably 1.5 to 7.0% by mass, based on the total composition. On the other hand, in the second embodiment, the content of the component (B) is more preferably 1.0 to 7.0% by mass, and still more preferably 1.5 to 5.0% by mass, based on the total composition.

[Metal Detergent]

The lubricating oil composition of each embodiment preferably contains a metal-based detergent, specifically, it preferably contains overbased calcium salicylate (C1) with a base value of 170 to 400 mgKOH/g and a group selected from Neutral metal-based detergent (C2) in neutral calcium sulfonate and neutral calcium salicylate with a base value of 50 mgKOH/g or less.

In the lubricating oil composition of each embodiment, the base number maintenance is ensured by the component (C1) with a high base number, and the detergency is also secured by using the component (C2) with a low base number in combination. By using these two Components that can further suppress the generation of sludge while ensuring high detergency. Furthermore, in the second embodiment, it is easy to prevent high-temperature deterioration of the lubricating oil composition and suppress turbine coking by making the desired content described later.

In addition, in each embodiment, it is preferable to use neutral calcium sulfonate among the above-mentioned as (C2) component.

In the first embodiment, the content of overbased calcium salicylate (C1) is preferably 0.5 to 4.0% by mass, more preferably 0.75 to 3.0% by mass, and even more preferably 1.0 to 2.0% by mass based on the total amount of the composition. %. In the first embodiment, by setting the content of the component (C1) within such a range, it is possible to increase the base number of the lubricating oil composition while reducing the sulfated ash content described later.

In the first embodiment, the content of the neutral metal-based detergent (C2) is preferably 0.3 to 3% by mass, more preferably 0.5 to 2.5% by mass, and even more preferably 0.6 to 1.5% by mass, based on the total amount of the composition. . In 1st Embodiment, by making content of (C2)component into such a range, it becomes easy to reduce a sulfated ash content, and it becomes easy to ensure high detergency.

In the second embodiment, the content of overbased calcium salicylate (C1) is preferably 1.5 to 6.0% by mass, more preferably 2.0 to 5.0% by mass, and even more preferably 2.5 to 4.0% by mass based on the total amount of the composition. %. In the second embodiment, by setting the content of the component (C1) in such a range, the base value of the lubricating oil composition can be increased to ensure long oil drain performance, and furthermore, the effect of suppressing turbo coking can be easily enhanced.

In the second embodiment, the content of the neutral metal-based detergent (C2) is less than the above-mentioned component (C1), preferably 0.3 to 3% by mass, more preferably 0.5 to 2.0% by mass, based on the total amount of the composition, More preferably, it is 0.6-1.5 mass %. In 2nd Embodiment, it becomes easy to ensure high detergency by making content of (C2)component into such a range. Moreover, by making content of (C2) component 0.6 mass % or more, the inhibitory effect of turbo coking becomes high.

Moreover, the base value of the overbased calcium salicylate (C1) in each embodiment is 170-400 mgKOH/g as mentioned above, Preferably it is 190-380 mgKOH/g, More preferably, it is 200-350 mgKOH/g. In the first embodiment, by setting the base number of the component (C1) within such a range, it is easy to make detergency favorable and suppress generation of sludge easily. In addition, in the second embodiment, by making the base number of the component (C1) fall within the above-mentioned range, the base number of the lubricating oil composition can also be increased, thereby achieving good detergency while suppressing the generation of sludge, and easily improving Inhibitory effect of turbo coking.

In addition, the base value of the (C2) component (ie, neutral calcium sulfonate and neutral calcium salicylate) in each embodiment is 50 mgKOH/g or less, preferably 10 to 40 mgKOH/g, more preferably 15 to 30 mgKOH/g. g. In the first embodiment, it is easy to improve the detergency of the lubricating oil composition by using a specific metal-based detergent having a low base number. In addition, in the second embodiment, by using a predetermined amount of a specific metal-based detergent with a low base number, it is easy to improve the detergency of the lubricating oil composition, and it is also easy to enhance the effect of suppressing turbo coking.

In addition, the lubricating oil composition contains calcium by blending the aforementioned components (C1) and (C2), and the calcium content in the lubricating oil composition in the first embodiment is preferably 500 to 1800 ppm by mass. In the first embodiment, by setting the calcium content of the composition in such a range, it is possible to reduce the sludge and ensure high detergency while suppressing the sulfuric acid ash content. From such a viewpoint, the calcium content in the lubricating oil composition in the first embodiment is more preferably 700 to 1600 mass ppm, and still more preferably 900 to 1500 mass ppm.

In addition, the calcium content in the lubricating oil composition in the second embodiment is preferably more than 1800 mass ppm and 3500 mass ppm or less. If it is more than 1800 mass ppm, the detergency can be improved and the generation of sludge can be suppressed. Furthermore, if the sulfated ash content is more than 0.7 mass %, the effect of suppressing turbo coking is excellent, and it is easy to ensure long oil drain performance. On the other hand, by making it 3500 mass ppm or less, the sulfated ash content becomes easily 1.2 mass % or less. From the above viewpoint, the calcium content in the lubricating oil composition in the second embodiment is more preferably 2000 to 3000 mass ppm, and still more preferably 2100 to 2900 mass ppm.

Examples of overbased calcium salicylate (C1) include those obtained by overbasing calcium salts of alkyl salicylic acids such as monoalkyl salicylic acid and dialkyl salicylic acid. substance. Moreover, the calcium salt of alkyl salicylic acid, such as monoalkyl salicylic acid and dialkyl salicylic acid, is mentioned as neutral calcium salicylate used as (C2) component. The alkyl group constituting the alkyl salicylic acid is preferably a linear or branched alkyl group having 4 to 30 carbon atoms, more preferably 8 to 22 carbon atoms.

As the neutral calcium sulfonate used as the component (C2), calcium salts of various sulfonic acids can be used. Here, as the sulfonic acid used, there are aromatic petroleum sulfonic acid, alkylsulfonic acid, arylsulfonic acid, alkylarylsulfonic acid, etc. Specifically, for example, dodecylbenzenesulfonic acid , Dilauryl cetyl benzene sulfonic acid, paraffin wax substituted benzene sulfonic acid, polyolefin substituted benzene sulfonic acid, polyisobutylene substituted benzene sulfonic acid, naphthalene sulfonic acid, etc.

In addition, in this specification, the base number of a metallic detergent means the base number measured by JISK-2501: Perchloric acid method.

[Ashless Dispersant]

The lubricating oil composition of each embodiment preferably further contains an ashless dispersant. Examples of the ashless dispersant include polybutenylsuccinimide (D1) and boron-modified polybutenylsuccinimide (D2), and the lubricating oil composition preferably contains both of them. By containing these compounds, the lubricating oil composition in the first embodiment can improve both heat resistance and dispersibility without increasing the sulfated ash content, and for example, it is easy to suppress the generation of sludge due to thermal deterioration. In addition, the lubricating oil composition in the second embodiment can also improve both heat resistance and dispersibility by containing these compounds in the same manner.

Examples of the polybutenylsuccinimide (D1) include compounds represented by the following general formulas (1) and (2).

[chemical formula 1]

.

[chemical formula 2]

.

PIB in these general formulas (1) and (2) represents a polybutene group, and its number average molecular weight is 750-3500 normally, Preferably it is 900-2000. When the number average molecular weight is 750 or more, the dispersibility is good, and when it is 3500 or less, the storage stability is good. Moreover, n in each of said general formula (1) and (2) is an integer of 1-5 normally, More preferably, it is an integer of 2-4.

The method for producing the compounds represented by these general formulas (1) and (2) is not particularly limited, and can be produced by known methods. For example, it can be obtained by reacting polybutene and maleic anhydride at a temperature of 100°C to 200°C to obtain polybutenylsuccinic acid, and combining the obtained polybutenylsuccinic acid with di It is obtained by reacting polyamines such as ethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

Further, as polybutenylsuccinimide (D1), compounds represented by general formulas (1) and (2) and alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy Modified polybutenyl succinimide obtained by reacting compounds, organic acids, etc.

As the boron-modified polybutenylsuccinimide (D2), there is a compound obtained by causing the above-mentioned polybutenylsuccinimide (D1) to act on a boron compound.

Examples of boron compounds include boric acid, borates, and borate esters. As boric acid, for example, orthoboric acid, metaboric acid, and pyroboric acid (paraboric acid) etc. are mentioned. In addition, examples of the borate include ammonium salts, for example, ammonium borates such as ammonium metaborate, ammonium tetraborate, ammonium pentaborate, and ammonium octaborate. In addition, boric acid esters include esters of boric acid and alkyl alcohol (preferably having 1 to 6 carbon atoms), such as monomethyl borate, dimethyl borate, trimethyl borate, monoethyl borate, Diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, dibutyl borate, tributyl borate and the like are suitable examples.

The total content of polybutenylsuccinimide (D1) and boron-modified polybutenylsuccinimide (D2) in each embodiment is calculated in terms of nitrogen atoms based on the total amount of lubricating oil composition Preferably it is 0.01-0.15 mass %, More preferably, it is 0.02-0.12 mass %. Moreover, it is more preferable that the said total content in 2nd Embodiment is 0.04-0.10 mass %. By being more than these lower limits, heat resistance and dispersibility become favorable, and it becomes easy to prevent generation|occurrence|production of sludge, etc. Moreover, if it is below an upper limit, the performance equivalent to content will be exhibited easily.

In addition, in each embodiment, the mass ratio B/ N is usually preferably 0.05 to 1.5, more preferably 0.15 to 1.2.

[Anti-wear agent]

The lubricating oil composition in each embodiment preferably contains zinc dithiophosphate (E) as an antiwear agent. As the zinc dithiophosphate (E), for example, one represented by the following general formula (3) can be used.

[chemical formula 3]

.

In the general formula (3), R ¹ to R ⁴ each independently represent a straight-chain or branched alkyl group with 1 to 24 carbon atoms, and a straight-chain or branched chain with 2 to 24 carbon atoms. The alkenyl groups or the aralkyl groups having 6 to 18 carbon atoms may be different from each other or the same. In the general formula (3), in the alkyl and alkenyl groups, the number of carbon atoms of R ¹ to R ⁴ is preferably 6 to 10, and in the aralkyl group, the number of carbon atoms is preferably 8 to 20. From the viewpoints of stability, Alkyl or aralkyl is preferred.

In the first embodiment, by using zinc dithiophosphate, wear resistance and oxidation stability can be improved with a small amount of use without excessively increasing the sulfated ash content.

In addition, in the second embodiment, by using zinc dithiophosphate, wear resistance can be improved with a small usage amount. In addition, high-temperature oxidative deterioration of the lubricating oil composition is prevented, and the occurrence of turbo coking is easily suppressed.

Examples of the alkyl group in R ¹ to R ⁴ include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl , n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n- Nonadecanyl, n-eicosyl, n-uncodecyl, n-docosyl, n-tricosyl, n-tetradecyl, and branched chain structures of these alkyl groups Construct.

In addition, examples of the alkenyl group include n-butenyl, n-pentenyl, n-hexenyl, n-heptenyl, n-octenyl, n-nonenyl, n-decenyl, n-undecenyl, n-dodecenyl, n-tridecenyl, n-tetradecenyl, n-pentadecenyl, n-hexadecenyl, n-heptadecenyl, n-octadecenyl, n- Nonadecenyl, n-eicosenyl, n-uncocenyl, n-dococenyl, n-tridecenyl, n-tetradecenyl, and these alkenyl groups Branched-chain structural isomers.

Examples of the aralkyl group include ethylphenyl, n-butylphenyl, n-propylphenyl, n-hexylphenyl, n-octylphenyl, n-nonylphenyl, n-decylphenyl, n-decylphenyl Dialkylphenyl groups and structural isomers in which their alkyl groups are branched.

In addition, R ¹ to R ⁴ are more preferably primary alkyl groups each independently representing a structure of R-CH ₂ - (where R is an alkyl group having 1 to 23 carbon atoms), and among them, n-hexyl-n- Straight-chain alkyl such as heptyl, n-octyl, n-nonyl, n-decyl; branched chain such as 2-methylpropyl, 2-methylbutyl, 2-methylhexyl, 2-ethylhexyl alkyl. In this way, by making R ¹ to R ⁴ a primary alkyl group or an aralkyl group, in the first and second embodiments, the oxidation stability of the lubricating oil composition can be further improved. Furthermore, in the second embodiment, it is easy to suppress the occurrence of turbo coking.

The content of the zinc dithiophosphate (E) in the first embodiment is preferably 100 to 1,000 ppm by mass, more preferably 150 to 800 ppm, and even more preferably 200 to 800 ppm in terms of phosphorus atoms based on the total amount of the lubricating oil composition. 600ppm. In 1st Embodiment, by making content of (E) component into such a range, abrasion resistance can be made favorable, suppressing the quantity of sulfated ash.

The content of the zinc dithiophosphate (E) in the second embodiment is preferably 100 to 1000 ppm by mass, more preferably 200 to 800 ppm by mass, and still more preferably 300~600 ppm by mass. In 2nd Embodiment, abrasion resistance can be made favorable by making content of (E) component more than these lower limits. Moreover, by making it more than the lower limit, high-temperature deterioration can be prevented and turbo-coking resistance can be improved easily. On the other hand, by making it below the upper limit, it becomes easy to exhibit the performance corresponding to the compounding quantity, and it becomes easy to make the sulfated ash content into 1.2 mass % or less.

[Antioxidants]

The lubricating oil composition of each embodiment preferably contains a hindered phenol compound (F1) and an alkyldiphenylamine compound (F2) as an antioxidant.

In the first embodiment, the lubricating oil composition can improve oxidation stability and improve high-temperature detergency by containing these two components as antioxidants. In addition, in the first embodiment, the total content of the hindered phenol compound (F1) and the alkyldiphenylamine compound (F2) is preferably more than 1.5 mass % and 5.0 mass % or less based on the total amount of the lubricating oil composition. . By making it more than 1.5% by mass, the detergency of the piston can be sufficiently improved. Moreover, the effect corresponding to the addition amount can be exhibited by making it 5.0 mass % or less.

In the first embodiment, from the viewpoint of improving oxidation stability and high-temperature detergency, the total content of the above-mentioned (F1) component and (F2) component is more preferably 2.0 to 4.5% by mass, and still more preferably 2.5 to 4.0% by mass. %.

In the second embodiment, the total content of the hindered phenol compound (F1) and the alkyldiphenylamine compound (F2) is preferably more than 1.5 mass % and 6.0 mass % or less based on the total amount of the lubricating oil composition.

As described above, lubricating oil for a four-stroke cycle engine preferably has high piston cleanliness, and in the second embodiment, it is also preferable to ensure high piston cleanliness.

The lubricating oil composition according to the second embodiment can improve oxidation stability and ensure high Piston cleanliness. Moreover, the effect corresponding to the addition amount can be exhibited by making it 6.0 mass % or less.

In the second embodiment, from the viewpoint of improving oxidation stability and piston detergency, the total content of the above-mentioned (F1) component and (F2) component is more preferably 2.0 to 5.5% by mass, and still more preferably 2.5 to 5.0% by mass. %.

It should be noted that in the first and second embodiments, the mass ratio (F2/F1) of the alkyldiphenylamine compound (F2) to the hindered phenol compound (F1) is not particularly limited, but is preferably 1/3 to 3 /1 or so, more preferably 1/2 to 2/1 or so.

Typical examples of the hindered phenol compound (F1) include compounds in which a tert-butyl group is substituted at the ortho position to the phenolic hydroxyl group, bisphenol-based compounds, monophenol-based compounds, and the like. Examples of bisphenol-based compounds include 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-bis(2,6-di-tert-butylphenol), 4 ,4'-isopropylidene bis(2,6-di-tert-butylphenol), bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, thiodiethylenebis[ 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 4,4'-bis(2-methyl-6-tert-butylphenol), 2,2'-methylene Base bis(4-ethyl-6-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3 -methyl-6-tert-butylphenol), 4,4'-thiobis(2-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6- tert-butylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), bis(3-methyl-4-hydroxy-5-tert-butylbenzyl)sulfide Wait.

In addition, examples of monophenol compounds include 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butyl-4-ethylphenol, etc., where the number of carbon atoms in the alkyl group is 1. ~4 2,6-di-tert-butyl-4-alkylphenol; 3-(4-hydroxy-3,5-di-tert-butylphenyl) n-octyl propanoate, 3-(3,5-di 6-methylheptyl tert-butyl-4-hydroxyphenyl) propionate, n-octadecyl 3-(4-hydroxy-3,5-di-tert-butylphenyl) propionate and other alkyl carbons Alkyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate with 4~12 atoms; 2,4-dimethyl-6-tert-butylphenol.

Among these, t-butyl groups are preferably substituted at two positions ortho to the phenolic hydroxyl group from the viewpoint of improving oxidation stability and high-temperature detergency.

Examples of the alkyldiphenylamine compound (F2) include mono-tert-butyldiphenylamine, monooctyldiphenylamine, and monononyldiphenylamine in which one phenyl group is substituted with a number of carbon atoms. Monoalkyl-substituted diphenylamines with 3~10 alkyl groups; 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-diphenylamine Hexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldiphenylamine, 4-butyl- 4'-octyldiphenylamine and other dialkyldiphenylamines whose alkyl groups have 3 to 10 carbon atoms; tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine Phenylamine, tetranonyldiphenylamine, bis(2,4-diethylphenyl)amine, bis(2-ethyl-4-nonylphenyl)amine, etc. have 3 or more alkyl groups and Polyalkyldiphenylamines having 1 to 10 carbon atoms in each alkyl group, etc., among these, dialkyldiphenylamines having 3 to 10 carbon atoms in each alkyl group are preferable.

[Other additives]

The lubricating oil composition may further contain other additives such as a pour point depressant, a metal inert agent, an anti-emulsifier, and an antifoaming agent.

Examples of the pour point depressant include polymethacrylate, polyacrylate, and the like. Examples of metal inactivators include benzotriazole-based, tolyltriazole-based, thiadiazole-based, imidazole-based, and pyrimidine-based compounds.

As the anti-emulsifier, surfactants can be used, such as polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxypropylene alkylphenyl ether and polyoxyethylene Polyalkylene glycol-based nonionic surfactants such as alkyl naphthyl ethers, and the like.

In addition, examples of the antifoaming agent include silicone oil, fluorosilicone oil, and fluoroalkyl ether.

[lubricating oil composition]

The lubricating oil composition in the first embodiment has a sulfated ash content of 0.3 to 0.7% by mass as described above. In the first embodiment, by using the component (B), the generation of sludge can be suppressed, and the detergency can be maintained at a good level. Therefore, in cooperation with the sulfuric acid ash content being reduced to 0.7% by mass or less, metal in the engine parts can be suppressed. Composition, dirt adhesion. Therefore, failures such as knocking can be prevented even if engine parts are cleaned infrequently.

In addition, in the first embodiment, by making the sulfated ash content 0.3% by mass or more, a certain amount of metal-based additives is used. Therefore, as described above, effects such as suppressing sludge, ensuring high detergency, and improving abrasion resistance are easily obtained by the action of the metal-based detergent, anti-wear agent, and the like.

From the above viewpoint, the sulfated ash content of the lubricating oil composition of the first embodiment is preferably 0.35 to 0.65% by mass, more preferably 0.40 to 0.60% by mass.

The lubricating oil composition in the second embodiment has a sulfated ash content of more than 0.7% by mass and 1.2% by mass or less as described above. In the second embodiment, by increasing the sulfuric acid ash content to more than 0.7% by mass, the metal component derived from the metal-based detergent and zinc dithiophosphate in the composition increases, so that high-temperature deterioration is suppressed in conjunction with the use of the above-mentioned component (B). , it is difficult to cause turbine coking in the lubricating oil composition, and it is also easy to ensure long oil drain performance.

In addition, by making the sulfated ash content 1.2% by mass or less, the amount of metal in the composition does not increase more than necessary, and metal components can be prevented from being deposited in a combustion chamber or the like. The lubricating oil composition of the second embodiment can achieve long oil drain performance, and thus can be operated for a long period of time without changing the lubricating oil composition. Furthermore, even if the lubricating oil composition of the second embodiment is used without replacement for a long period of time, metal components are less likely to precipitate as described above, and knocking or the like does not occur until replacement.

From the above viewpoint, the sulfated ash content of the lubricating oil composition of the second embodiment is preferably 0.80 to 1.15% by mass, more preferably 0.90 to 1.10% by mass.

The kinematic viscosity at 100°C of the lubricating oil composition of each embodiment is preferably 6.9 mm ² /s or more and less than 21.9 mm ² /s, more preferably 9.3 mm ² /s or more and less than 18.0 mm ² /s, More preferably, it is 9.3 mm ² /s or more and less than 16.3 mm ² /s. The lubricating oil compositions according to the first and second embodiments can be suitably used in an engine operating under a high load, especially a gas cogeneration system, by setting the kinematic viscosity at 100° C. within such a range.

The lubricating oil composition of each embodiment is used as an engine oil for lubricating between components in a four-stroke cycle engine.

In addition, the lubricating oil composition of the first embodiment is suitable for use in a four-stroke cycle engine that operates continuously under a high load in ships, stationary power generation equipment, and the like. As such a four-stroke cycle engine, specifically, an engine with a maximum output of 200 kW or more, continuously operated at 60% or more of the maximum output for 10 hours or more, and an engine with an oil change cycle of 500 hours or more . It should be noted that the so-called "time" in the oil change cycle refers to the total time the engine is running.

Even if the lubricating oil composition of the first embodiment is used in such a four-stroke cycle engine that operates continuously under a high load, the piston detergency is good, and the generation of sludge is also suppressed. Knocking caused by adhesion to engine parts, etc. Therefore, it is possible to reduce the cleaning work of the engine parts at the time of oil replacement, and reduce the burden of maintenance.

The lubricating oil composition of the second embodiment is suitable for use in a four-stroke cycle engine that operates continuously at a high load and is equipped with a turbocharger in ships or stationary power generation equipment. As such a four-stroke cycle engine, specifically, an engine with a maximum output of 200 kW or more, continuously operating at 60% or more of the maximum output for 10 hours or more, and an engine with an oil change cycle of 1000 hours or more.

Even when the lubricating oil composition of the second embodiment is used in a four-stroke cycle engine that operates continuously under a high load as described above, the piston detergency is good and the generation of sludge is also suppressed. Furthermore, high-temperature deterioration is prevented, the turbo coking suppression effect is good, and long oil drain intervals are ensured.

The lubricating oil compositions of the first and second embodiments are suitable for use in gas engines, particularly gas cogeneration systems.

[Method for producing lubricating oil composition for four-stroke cycle engine]

In the method for producing a lubricating oil composition for a four-stroke cycle engine in the first embodiment, the polyolefin (B) is blended into the base oil (A) and adjusted so that the sulfated ash content becomes 0.3 to 0.7% by mass to obtain A lubricating oil composition for a four-stroke cycle engine.

Furthermore, in the method for producing a lubricating oil composition for a four-stroke cycle engine in the second embodiment, the polyolefin (B) is blended into the base oil (A) and adjusted so that the sulfated ash content exceeds 0.7% by mass and becomes 1.2% by mass. mass% or less, thereby obtaining a lubricating oil composition for a four-stroke cycle engine.

In each of the above-mentioned production methods, the details of the base oil (A) and the polyolefin (B) are as above, and the amounts (blend amounts) of each component are also the same as the above-mentioned contents, and the description thereof is omitted.

In addition, the above-mentioned metal-based detergent, ashless dispersant, anti-wear agent, antioxidant, and other additives are optionally mixed in the same amount as the above-mentioned content, and adjusted so that the sulfated ash content reaches 0.3 to 1.2 mass % (0.3 to 0.7% by mass in the first embodiment, more than 0.7% by mass and 1.2% by mass or less in the second embodiment). In addition, since the detail of the lubricating oil composition obtained by this method is the same as above, description is abbreviate|omitted.

In this production method, each component may be blended into the base oil by any method, and the method and blending order are not limited.

Example

Next, the present invention will be described in more detail through examples, but the present invention is not limited by these examples.

The measurement method of each property was calculated|required according to the procedure mentioned below.

(1) Kinematic viscosity

The value measured using the glass capillary viscometer according to JISK2283-2000.

(2) Sulfur content

Measured in accordance with JIS K2541.

(3) Base value

The base value of the metal detergent and lubricating oil composition is a value measured by the perchloric acid method in accordance with JIS K-2501-2003.

(4) Sulfated ash

Measured in accordance with JIS K2272.

(5) Number average molecular weight, weight average molecular weight

The number-average molecular weight and weight-average molecular weight of each component were measured under the following conditions and calculated in terms of standard polystyrene: Model HLC-8220 manufactured by Tosoh, with a Tosoh column installed: TSKgel GMH-XL 2 pieces + G2000H-XL 1 root, detector: refractive index detector, measurement temperature: 40°C, mobile phase: tetrahydrofuran, flow rate: 1.0ml/min, concentration: 1.0mg/ml.

(6) Calcium content

Calcium content in lubricating oil compositions is measured in accordance with JPI-5S-38-03.

(7) Heat pipe test

According to JPI-5S-5599, it implemented at the measurement temperature of 310 degreeC. The lacquer attached to the glass tube was compared with the standard color, and the case of transparency was scored as 10 points, and the case of black was scored as 0 point, and the quality of the varnish attached to the glass tube was measured. Higher scores, with less varnish in addition, indicate higher performance.

(8) Panel coking test

According to Fed. Test Method Std. 791-3462, under the conditions of panel temperature 300°C, 310°C, or 320°C, and oil temperature 100°C, the test was carried out for 3 hours with a cycle of sputtering time of 15 seconds and stop time of 45 seconds. After the test, the adhesion amount of the coke adhering to the panel was evaluated.

(9) High temperature deterioration test (turbine coking resistance test)

0.5 g of the test oil was put into an iron dish-shaped container with a diameter of 35 mm and a height of 3 mm, and the state of the residue after heating at 250° C. for 6 hours was observed and evaluated according to the following evaluation criteria.

A: Liquidity B: No liquidity.

[Examples 1-5, Comparative Examples 1-4]

Lubricating oil compositions of Examples and Comparative Examples formulated in Table 1 were produced, and properties of the lubricating oil compositions were measured. In addition, the lubricating oil compositions of Examples and Comparative Examples were evaluated by a heat pipe test and a panel coking test. The results are shown in Table 1. It should be noted that the panel coking test was performed at panel temperatures of 300°C and 320°C.

[Table 1]

.

※The calcium content and phosphorus content are the calcium content and phosphorus content in each lubricating oil composition, expressed based on the total amount of the composition.

※ Each component in Table 1 is shown below.

Base oil: 500N mineral oil (hydrorefined mineral oil), kinematic viscosity at 100°C: 10.9 mm ² /s, sulfur content: 0.01% by mass or less, API classification: Class 2

Polybutene-1: polyisobutene, number average molecular weight 850, not hydrogenated

Polybutene-2: polyisobutene, number average molecular weight 950, not hydrogenated

Polybutene-3: polyisobutene, number average molecular weight 1800, not hydrogenated

Polybutene-4: polyisobutylene, number average molecular weight 4500, hydride

Polybutene-5: polyisobutene, number average molecular weight 30,000, unhydrogenated

Bright stock: 150BS mineral oil (hydrorefined mineral oil), kinematic viscosity at 100°C of 33.3 mm ² /s, sulfur content of 0.01% by mass or less

OCP-1: Ethylene-propylene copolymer, weight average molecular weight 91000

OCP-2: Styrene/isoprene block copolymer, weight average molecular weight: 132500

Metal-based detergent A: overbased calcium salicylate, calcium content: 7.8% by mass, base value: 225 mgKOH/g

Metal-based detergent B: calcium sulfonate, calcium content: 2.35% by mass, base value: 17 mgKOH/g

Ashless dispersant A: polybutenylsuccinimide, nitrogen content 1.0% by mass

Ashless dispersant B: boron-modified polybutenylsuccinimide, nitrogen content 1.23% by mass, boron content 1.3% by mass

Anti-wear agent: zinc di(2-ethylhexyl)dithiophosphate, phosphorus content: 7.40% by mass, zinc content: 8.9% by mass

Antioxidant: a mixture of antioxidant F1 and antioxidant F2 (F2/F1 (mass ratio) = 2/1.5)

Antioxidant F1: a mixture of alkyl 3-(4-hydroxy-3,5-di-tert-butylphenyl) propionate (wherein the alkyl is a mixture of alkyl groups with 7 to 9 carbon atoms)

Antioxidant F2: Dioctyldiphenylamine

Other additives: pour point depressant, metal inert agent, defoamer, anti-emulsifier.

As described above, in Examples 1 to 5, since the polybutene with a predetermined molecular weight was blended, the kinematic viscosity was adjusted to an appropriate value, and the results of the heat pipe test and the panel coking test were also good, excellent in detergency, and also Can prevent the generation of sludge. In contrast, in Comparative Examples 1 to 4, bright stock, OCP, or polybutene with a large molecular weight was used instead of polybutene, so at least any one of the heat pipe test and the panel coking test deteriorated. , it is impossible to achieve good detergency while suppressing the occurrence of sludge.

[Examples 6-9, Comparative Examples 5-7]

The lubricating oil compositions of Examples and Comparative Examples formulated as shown in Table 2 were produced, and the properties of the lubricating oil compositions were measured. In addition, the lubricating oil compositions of the respective Examples and Comparative Examples were evaluated by a panel coking test and a high-temperature deterioration test. The results are shown in Table 2. It should be noted that the panel coking test was performed at panel temperatures of 300°C and 310°C.

[Table 2]

.

※The calcium content and phosphorus content are the calcium content and phosphorus content in each lubricating oil composition, expressed based on the total amount of the composition.

Among the components in Table 2, polybutene-6 is as follows, and other components are the same as above.

Polybutene-6: Polyisobutene with a number average molecular weight of 750, not hydrogenated.

As described above, in Examples 6 to 9, polybutene with a predetermined molecular weight was blended, and various additives were blended so that the sulfated ash content exceeded 0.7% by mass, so the kinematic viscosity was adjusted to an appropriate value, and the panel coking test The results were good and sludge was suppressed. Furthermore, the result of the high-temperature deterioration test was good, and the turbo-coking resistance was good. Thus, in this example, in the lubricating oil composition with a high sulfated ash content, since the sludge is suppressed and the turbo-coking resistance is good, it is easy to ensure a long drain period.

In contrast, in Comparative Examples 5 to 7, bright stock, OCP, or polybutene with a large molecular weight was used instead of polybutene, so the results of the panel coking test deteriorated, and it was not possible to achieve good detergency while suppressing Sludge occurs. Furthermore, good results were not obtained in the high-temperature deterioration test, and the effect of suppressing turbo coking was low.

Furthermore, about Examples 6-9, the heat pipe test was implemented also. The test results are shown below. As shown in Table 3 below, in Examples 6 to 9, the results of the heat pipe test were good, and the piston detergency was also good.

[table 3]

.

Claims (20)

1. A lubricating oil composition for a four-stroke cycle engine, comprising a base oil (A) and 0.5 to 10% by mass of polyolefin (B), The polyolefin (B) has at least a structural unit derived from isobutylene and has a number average molecular weight of 500 to 10,000, The sulfated ash content of the lubricating oil composition is 0.3-1.2% by mass. 2. The lubricating oil composition for a four-stroke cycle engine according to claim 1, wherein the sulfated ash content is 0.3 to 0.7% by mass. 3. The lubricating oil composition for a four-stroke cycle engine according to claim 2, comprising: Overbased calcium salicylate (C1) with a base value of 170~400mgKOH/g, and A neutral metal-based detergent (C2) selected from neutral calcium sulfonate with a base value of 50 mgKOH/g or less and neutral calcium salicylate with a base value of 50 mgKOH/g or less; The calcium content of the lubricating oil composition is 500 to 1,800 ppm by mass. 4. The four-stroke cycle engine lubricating oil composition according to claim 2 or 3, which also contains hindered phenolic compounds (F1) and alkyldiphenylamine compounds (F2), and their total content is represented by the composition The total amount is based on more than 1.5 mass % and 5.0 mass % or less. 5. The lubricating oil composition for a four-stroke cycle engine according to any one of claims 2 to 4, which is used for a maximum output power of more than 200kW, and continuously for more than 60% of the maximum output power for more than 10 hours A four-stroke cycle engine with an oil replacement cycle of more than 500 hours. 6 . The lubricating oil composition for a four-stroke cycle engine according to claim 1 , wherein the sulfated ash content is greater than 0.7 mass % and 1.2 mass % or less. 7. The lubricating oil composition for a four-stroke cycle engine according to claim 6, comprising: Overbased calcium salicylate (C1) with a base value of 170~400mgKOH/g, and A neutral metal-based detergent (C2) selected from neutral calcium sulfonate with a base value of 50 mgKOH/g or less and neutral calcium salicylate with a base value of 50 mgKOH/g or less; The calcium content of the lubricating oil composition is more than 1800 mass ppm and 3500 mass ppm or less. 8. The lubricating oil composition for a four-stroke cycle engine according to claim 6 or 7, which also contains hindered phenolic compounds (F1) and alkyldiphenylamine compounds (F2), and their total content is represented by the composition The total amount is based on more than 1.5 mass % and 6.0 mass % or less. 9. The lubricating oil composition for a four-stroke cycle engine according to any one of claims 6 to 8, which is used for a maximum output power of more than 200kW, and continuously for more than 60% of the maximum output power for more than 10 hours A four-stroke cycle engine with an oil replacement cycle of more than 1000 hours. 10. The lubricating oil composition for a four-stroke cycle engine according to any one of claims 1 to 9, wherein the polyolefin (B) is polybutene. 11. The lubricating oil composition for a four-stroke cycle engine according to claim 10, wherein the polybutene is polyisobutylene. 12. The lubricating oil composition for a four-stroke cycle engine according to claim 10 or 11, wherein the polybutene is not hydrogenated. 13. The lubricating oil composition for a four-stroke cycle engine according to any one of claims 1 to 12, further comprising polybutenyl succinimide (D1), and boron-modified polybutenyl Succinimide (D2). 14. The lubricating oil composition for a four-stroke cycle engine according to any one of claims 1 to 13, comprising 100 to 1000 mass ppm of disulfide in terms of phosphorus atom conversion relative to the total amount of the lubricating oil composition Zinc phosphate (E). 15 . The lubricating oil composition for a four-stroke cycle engine according to claim 1 , wherein the kinematic viscosity at 100° C. is 6.9 mm ² /s or more and less than 21.9 mm ² /s. 16. The lubricating oil composition for a four-stroke cycle engine according to any one of claims 1 to 15, which is used in a gas cogeneration system. 17. Lubricating method, by lubricating oil composition for four-stroke cycle engine described in any one in claim 1～16, lubricate between each part in the four-stroke cycle engine. 18. A method for producing a lubricating oil composition for a four-stroke cycle engine, comprising blending 0.5 to 10% by mass of a polyolefin (B) based on the total amount of the lubricating oil composition to the base oil (A), and adjusting to The sulfated ash content is 0.3-1.2% by mass to obtain a lubricating oil composition for a four-stroke cycle engine. The polyolefin (B) has at least a structural unit derived from isobutylene and has a number-average molecular weight of 500-10,000. 19. The method for producing a lubricating oil composition for a four-stroke cycle engine according to claim 18, wherein the sulfated ash content is 0.3 to 0.7% by mass. 20 . The method for producing a lubricating oil composition for a four-stroke cycle engine according to claim 18 , wherein the sulfated ash content is greater than 0.7 mass % and is 1.2 mass % or less.