TWI836351B - Lubricating oil composition for internal combustion engine - Google Patents

Abstract

The lubricating oil composition for internal combustion engines of the present invention contains (A) lubricating oil base oil and (B) metal-based detergent. The above-mentioned (B) component contains (B1) calcium content based on the total mass of the composition. A calcium-based detergent within a specific range, and (B2) a magnesium-based cleanser with a magnesium content within a specific range based on the total mass of the composition, where the above (B1) component contains (B1-1) containing boron and For calcium-based detergents, the boron content based on the total mass of the composition is 1000 mass ppm or less, and the boron content in component (B1) based on the total mass of the composition is expressed as B _{( B1)} , the calcium content in component (B1) based on the total mass of the composition is expressed as Ca _(B1) , and the magnesium content in component (B2) based on the total mass of the composition is expressed as In the case of Mg _(B2) , the ratio of B _(B1) to Ca _{(B1 ) (B (B1)} /Ca _(B1) ) is 0.15 or more and 0.35 or less, and the ratio of B _(B1) to Ca _(B1) and Mg The ratio (B (B1) /[Ca _{( B1)} +Mg _(B2) ]) of the total amount of _(B2) (Ca _(B1) +Mg _(B2) ) is 0.13 or more and 0.29 or less.

Description

Lubricating oil composition for internal combustion engine

The present invention relates to a lubricating oil composition for internal combustion engines.

In recent years, as the performance and output of internal combustion engines such as automobile engines have become higher, higher performance has been required of lubricating oils (motor oils) for internal combustion engines, and various lubricating oil compositions in which lubricating oil base oils are blended with various additives have been studied.

For example, in International Publication No. 2019/221295 (Patent Document 1), a lubricating oil composition for an internal combustion engine is disclosed, which comprises a lubricating oil base oil, (A) a metal-based cleaner containing calcium borate, and (B) a metal-based cleaner containing magnesium, wherein the component (A) is one or more calcium-based cleaners peralkalized with calcium borate, or is a metal-based cleaner containing magnesium. In a combination of at least one calcium-based cleaning agent peralkalized with calcium borate and at least one calcium-based cleaning agent not peralkalized with calcium borate, a molar ratio B/Ca of a total amount of boron (unit: mol) derived from the metal-based cleaning agent in the lubricating oil composition to a total amount of calcium (unit: mol) derived from the metal-based cleaning agent in the lubricating oil composition is at least 0.52.

In addition, International Publication No. 2018/212340 (Patent Document 2) discloses a lubricating oil composition for an internal combustion engine comprising a lubricating oil base oil, (A) a metallic detergent containing calcium borate, and (B) a metallic detergent containing magnesium. In paragraph [0064] of the document, it is disclosed that the molar ratio B/Ca of the total boron content B (unit: mol) derived from the metallic detergent in the lubricating oil composition to the total calcium content Ca (unit: mol) derived from the metallic detergent in the lubricating oil composition is preferably 0.52 or more.

Furthermore, Japanese Patent Laid-Open No. 2017-226793 (Patent Document 3) discloses a lubricating oil composition for an internal combustion engine, which contains (A) a lubricating base oil and (B) a metallic detergent, wherein (B) ) The metal-based cleaning agent includes (B1) a metal-based cleaning agent containing calcium and (B2) a metal-based cleaning agent containing magnesium. Based on the total amount of the composition, the amount of calcium is 500 to 2500 ppm by mass, and the amount of magnesium is Calculated as 100~1000 mass ppm. Prior technical literature patent documents

Patent Document 1: International Publication No. 2019/221295 Patent Document 2: International Publication No. 2018/212340 Patent Document 3: Japanese Patent Application Publication No. 2017-226793

[Problem to be solved by the invention]

However, even the conventional lubricating oil compositions for internal combustion engines described in the above-mentioned Patent Documents 1 to 3 have poor performance in suppressing LSPI (Low Speed Pre-Ignition, low speed pre-ignition) (LSPI suppression capability). ) is excellent, and there is still room for improvement in improving friction performance while also achieving excellent fuel consumption performance.

The present invention is made in view of the problems existing in the above-mentioned prior art, and its purpose is to provide a lubricating oil composition for internal combustion engines that can achieve excellent LSPI suppression ability and fuel consumption performance. [Technical means to solve the problem]

The inventors of the present invention have conducted intensive research to achieve the above-mentioned purpose, and have found that the lubricating oil composition for internal combustion engines can have excellent LSPI suppression ability, improve friction performance and also have excellent fuel consumption performance by setting the lubricating oil composition for internal combustion engines as follows, thereby completing the present invention, that is, the lubricating oil composition for internal combustion engines contains (A) a lubricating oil base oil and (B) a metallic cleaning agent, and the above-mentioned (B) component contains (B1) a calcium content of 1650 mass ppm based on the total mass of the composition. (B1-1) a calcium-based cleaner containing boron and calcium, wherein the content of boron based on the total mass of the composition is set to 1000 mass ppm or less, and (B2) a magnesium-based cleaner having a content of magnesium based on the total mass of the composition in a range of 20 mass ppm to 400 mass ppm, wherein the component (B1) contains (B1-1) a calcium-based cleaner containing boron and calcium, wherein the content of boron based on the total mass of the composition is set to 1000 mass ppm or less, and wherein the content (mass ratio) of boron in the component (B1) based on the total mass of the composition is expressed as B _(B1) , when the content (mass ratio) of calcium in the component (B1) based on the total mass of the composition is represented by Ca _(B1) , and the content (mass ratio) of magnesium in the component (B2) based on the total mass of the composition is represented by Mg _(B2) , the ratio of B _(B1) to Ca _(B1) (B _(B1) /Ca _(B1) ) is 0.15 to 0.35, and the ratio of B _(B1) to the total amount of Ca _(B1) and Mg _(B2) (Ca _(B1) +Mg _(B2) ) (B _(B1) /[Ca _(B1) +Mg _(B2) ]) is 0.13 to 0.29.

That is, the lubricating oil composition for internal combustion engines of the present invention contains (A) lubricating oil base oil and (B) metallic detergent, and the above-mentioned (B) component contains (B1) calcium based on the total mass of the composition. Calcium-based detergents with a content in the range of 1,650 ppm by mass or more and 2,500 ppm by mass or less, and (B2) magnesium with a magnesium content in the range of 20 ppm by mass or more and 400 ppm by mass or less based on the total mass of the composition. It is a cleaning agent. The above component (B1) contains (B1-1) a calcium-based cleaning agent containing boron and calcium. The content of boron based on the total mass of the composition is 1000 mass ppm or less, and the composition is to be used. The boron content in the component (B1) based on the total mass is expressed as B _(B1) , and the calcium content in the component (B1) based on the total mass of the composition is expressed as Ca _(B1). When the magnesium content in component (B2) is expressed as Mg _(B2 ) based on the total mass of the substance, the ratio of B _(B1) to Ca _(B1) (B _(B1) /Ca _(B1) ) is 0.15 or more and 0.35 or less, and the ratio of B _(B1) to the total amount of Ca _(B1) and Mg _(B2) (Ca _(B1) + Mg _(B2) ) (B _(B1) / [Ca _(B1) + Mg _{(B2) )} ]) is above 0.13 and below 0.29. In this specification, "the content of boron in component (B1) based on the total mass of the composition", "the content of calcium in component (B1) based on the total mass of the composition" and "based on the combination In the description "Content of magnesium in component (B2) based on the total mass of the composition", the description "content" means the ratio of the mass based on the total mass of the composition (total amount of the composition). Mass ratio: content ratio based on mass).

The lubricating oil composition for an internal combustion engine of the present invention preferably contains calcium borate salicylate as the component (B1-1) as the component (B1).

Moreover, it is preferable that the lubricating oil composition for internal combustion engines of the present invention further contains (C) a poly(meth)acrylate-based viscosity index improver. Moreover, it is preferable that the said (C) component contains a comb-shaped poly(meth)acrylate polymer. [Effects of the invention]

According to the present invention, it is possible to provide a lubricating oil composition for an internal combustion engine that is excellent in both LSPI suppressing ability and fuel consumption saving performance.

The present invention is described in detail below according to the preferred embodiment of the present invention. In addition, in this specification, regarding the numerical values X and Y, unless otherwise specified, the expression "X to Y" means "X or more and Y or less". When a unit is added to the numerical value Y in the expression, the unit also applies to the numerical value X.

The lubricating oil composition for internal combustion engines of the present invention comprises (A) a lubricating oil base oil and (B) a metal-based detergent. The component (B) comprises (B1) a calcium-based detergent having a calcium content of 1650 mass ppm to 2500 mass ppm based on the total mass of the composition, and (B2) a magnesium-based detergent having a magnesium content of 20 mass ppm to 400 mass ppm based on the total mass of the composition. The component (B1) comprises (B1-1) a calcium-based detergent containing boron and calcium. The boron content of the component (B1) based on the total mass of the composition is 1000 mass ppm or less, and the boron content (mass ratio) in the component (B1) based on the total mass of the composition is expressed as B _(B1) , the content (mass ratio) of calcium in the component (B1) based on the total mass of the composition is represented by Ca _(B1) , and the content (mass ratio) of magnesium in the component (B2) based on the total mass of the composition is represented by Mg _(B2) , the ratio of B _(B1) to Ca _(B1) (B _(B1) /Ca _(B1) ) is 0.15 to 0.35, and the ratio of B _(B1) to the total amount of Ca _(B1) and Mg _(B2) (Ca _(B1) +Mg _(B2) ) (B _(B1) /[Ca _(B1) +Mg _(B2) ]) is 0.13 to 0.29. First, the components that can be contained in the lubricating oil composition for internal combustion engines of the present invention are described below.

＜(A) Component: Lubricating base oil＞ In the present invention, the lubricating base oil used as component (A) is not particularly limited. Known base oils available in the lubricating oil field can be appropriately used. For example, one or more mineral oil-based base oils or one kind can be used. The above synthetic base oils, or their mixed base oils.

As the mineral oil-based base oil that can be used as the above-mentioned lubricating oil base oil, Group II base oil, Group III base oil, Group IV base oil, Group V base oil, or a mixture of two or more of these base oils (mixed base oil) in the base oil classification of API (American Petroleum Institute) can be appropriately used (hereinafter, the group of API base oil classification is referred to as "API group"). Here, API Group II base oil is a mineral oil-based base oil with a sulfur content of 0.03% by mass or less, a saturated content of 90% by mass or more, and a viscosity index of 80 or more and less than 120. API Group III base oil is a mineral oil-based base oil with a sulfur content of 0.03% by mass or less, a saturated content of 90% by mass or more, and a viscosity index of 120 or more. In addition, API Group IV base oil is a poly-α-olefin base oil. Furthermore, API Group V base oil refers to base oils other than API Groups I to IV, and ester base oils can be cited as a preferred example.

Furthermore, as the mineral oil-based base oil, for example, there can be used a wax-based mineral oil obtained by refining a lubricating oil fraction obtained by atmospheric distillation and/or reduced pressure distillation of crude oil by one or a combination of two or more refining treatments selected from solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, sulfuric acid washing, clay treatment, etc., and a normal wax-based base oil, an iso-wax-based base oil, and a mixture thereof.

As a preferred example of the mineral oil-based base oil, the base oils (1) to (8) shown below are used as raw materials, and the raw material oils and/or the raw material oils are extracted from the raw material oils using a predetermined refining method. The recovered lubricating oil fraction is refined, and the base oil obtained by recovering the lubricating oil fraction is obtained. (1) Distillate oil obtained by atmospheric distillation of paraffinic crude oil and/or mixed crude oil (2) Distillate oil (WVGO) obtained by vacuum distillation of the atmospheric distillation residue of paraffinic crude oil and/or mixed crude oil (3) Waxes (pine wax, etc.) obtained through the dewaxing step of lubricating oil and/or synthetic waxes (Fischer-Tropsch wax, GTL wax, etc.) obtained through the gas-to-liquid (GTL) process, etc. (4) One or more mixed oils selected from the base oils (1) to (3) and/or a moderately hydrocracked oil of the mixed oils (5) Mixed oils selected from two or more types of base oils (1) to (4) (6) Deasphalted oil (DAO) of base oil (1), (2), (3), (4) or (5) (7) Moderate hydrocracking oil (MHC) of base oil (6) (8) A mixed oil of two or more types selected from the base oils (1) to (7).

Furthermore, the above-mentioned refining methods are preferably: hydro-refining such as hydrocracking and hydrogen supplementary refining; solvent refining such as furfural solvent extraction; dewaxing such as solvent dewaxing or contact dewaxing; clay refining using acid clay or activated clay; chemical (acid or alkali) washing such as sulfuric acid washing and caustic soda washing, etc. One of the refining methods may be performed alone, or two or more of the refining methods may be combined. In addition, when two or more refining methods are combined, the order is not particularly limited and can be appropriately selected.

In addition, the mineral oil-based base oil is particularly preferably obtained by subjecting a base oil selected from the above-mentioned base oils (1) to (8) or a lubricating oil fraction recovered from the base oil to a prescribed treatment. Base oil (9) or (10). (9) Hydrocracked base oil, which is obtained by hydrocracking a base oil selected from the above base oils (1) to (8) or a lubricating oil fraction recovered from the base oil. , and perform dewaxing treatment such as solvent dewaxing or contact dewaxing on the product or the lubricating oil fraction recovered from the product by distillation or the like, or perform distillation after the dewaxing treatment (10) Hydroisomerized base oil, which is obtained by hydrogenating and isomerizing a base oil selected from the above base oils (1) to (8) or a lubricating oil fraction recovered from the base oil. structure, and perform dewaxing treatment such as solvent dewaxing or contact dewaxing on the product or the lubricating oil fraction recovered from the product by distillation, etc., or carry out distillation after such dewaxing treatment Furthermore, it is more preferable that the lubricating base oils of the above (9) and (10) are produced through contact dewaxing treatment (step) as dewaxing treatment. In addition, when obtaining the lubricating base oil of the above (9) or (10), solvent refining treatment and/or hydrogenation supplementary refining treatment step may also be performed at an appropriate stage if necessary.

The % _CP of the mineral oil-based base oil is preferably 70 to 99, more preferably 70 to 95, further preferably 75 to 95, particularly preferably 75 to 94. When the % _CP of the base oil is equal to or higher than the above-mentioned lower limit, the viscosity-temperature characteristics can be improved, and the fuel consumption-saving performance can be further improved. In addition, when an additive is blended with the base oil, the effectiveness of the additive can be fully exerted. In addition, when the % _CP of the base oil is below the above-mentioned upper limit, the solubility of the additive can be improved.

The %C _A of the mineral oil-based base oil is preferably 2 or less, more preferably 1 or less, further preferably 0.8 or less, particularly preferably 0.5 or less. By keeping the %C _A of the base oil below the above upper limit, the viscosity-temperature characteristics can be improved, and the fuel consumption saving performance can be further improved.

The % _CN of the mineral oil-based base oil is preferably 1 to 30, more preferably 4 to 25. When the % _CN of the base oil is below the upper limit, the viscosity-temperature characteristics can be improved, and the fuel consumption performance can be further improved. In addition, when the % _CN is above the lower limit, the solubility of the additive can be improved.

In this specification, % _CP , % _CN and % _CA respectively mean the percentage of paraffin carbon number relative to the total carbon number calculated by the method of ASTM D 3238-85 (ndM ring analysis). The percentage of naphthenic carbon number relative to the total carbon number, and the percentage of aromatic carbon number relative to the total carbon number. That is, the preferable ranges of the above % _CP , % _CN and %C _A are based on the values calculated by the above method. For example, even for lubricating base oils that do not contain naphthenic components, the values are calculated by the above method. %C _N can also display values exceeding 0.

The content of saturated components in the mineral oil-based base oil is preferably 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more, based on the total amount of the base oil. When the content of saturated components is greater than the above lower limit, the viscosity-temperature characteristics can be improved. In addition, in this specification, the so-called saturated components refer to the values measured according to ASTM D 2007-93.

In addition, for the separation method of saturated components, similar methods that obtain the same results can be used. For example, in addition to the method described in the above-mentioned ASTM D 2007-93, there are also the method described in ASTM D 2425-93, the method described in ASTM D 2549-91, and the method using high performance liquid chromatography (HPLC). Methods, or methods that improve these methods, etc.

The aromatic component in the mineral oil base oil is based on the total amount of the base oil, preferably 0 to 10 mass%, more preferably 0 to 5 mass%, especially 0 to 1 mass%, in one embodiment. It may be 0.1% by mass or more. By keeping the content of aromatic components below the above upper limit, the viscosity-temperature characteristics and low-temperature viscosity characteristics can be improved. In addition, the fuel consumption performance can be further improved, and the evaporation loss of lubricating oil can be reduced, thereby reducing the consumption of lubricating oil. quantity. In addition, the effect of additives blended in lubricating oil can be effectively exerted. In addition, the lubricating base oil may not contain aromatic components. However, when the content of aromatic components is equal to or higher than the above-mentioned lower limit, the solubility of the additive can be improved. In addition, in this specification, the so-called aromatic component means the value measured in accordance with ASTM D 2007-93. Among the aromatic components, they usually include alkylbenzenes, alkylnaphthalenes, anthracenes, phenanthrenes and their alkylates, and further include compounds formed by shrinking four or more benzene rings, pyridines, and quinolines. aromatic compounds with heteroatoms such as phenols, naphthols, etc.

The synthetic base oil that can be used as the lubricating oil base oil is not particularly limited, and known synthetic base oils can be appropriately used. Examples of such synthetic base oils that can be used include poly-α-olefins and their hydrogenated products, isobutylene oligomers and their hydrogenated products, isomeric paraffins, alkylbenzenes, alkylnaphthalenes, diesters (bis(decaglutarate) Trialkyl) ester, bis-2-ethylhexyl adipate, diisodecyl adipate, di(tridecyl) adipate, bis-2-ethylhexyl sebacate, etc. ), polyol esters (trimethylolpropane caprylate, trimethylolpropane nonanoate, pentaerythritol 2-ethylhexanoate, pentaerythritol nonanoate, etc.), polyoxyalkylene glycol, dioxane Synthetic base oils such as diphenyl ether, polyphenylene ether, and mixtures thereof, among which poly-α-olefin base oils are preferred. Typical examples of poly-α-olefin base oils include oligomers or co-oligomers (1-octene oligomers) of α-olefins having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms. , decene oligomers, ethylene-propylene co-oligomers, etc.) and their hydrogenation products.

The lubricating base oil preferably has a kinematic viscosity at 100°C of 2.0 to 5.0 mm ² /s (more preferably 3.0 to 5.0 mm ² /s, further preferably 4.0 to 4.8 mm ² /s, and particularly preferably 4.1 to 4.7 mm ² /s). When the kinematic viscosity at 100°C of the lubricating base oil is above the lower limit, an oil film can be formed more efficiently at the lubricating position, and evaporation loss of the lubricating oil composition can be reduced, thereby reducing the consumption of the lubricating oil. When the kinematic viscosity at 100°C of the lubricating base oil is below the upper limit, fuel saving performance can be improved compared to when it exceeds the upper limit. In this specification, the so-called "kinematic viscosity at 100°C" means the kinematic viscosity at 100°C measured according to JIS K 2283-2000.

The lubricating base oil preferably has a kinematic viscosity at 40°C of 9.0 to 36.0 mm ² /s (more preferably 12.6 to 33.2 mm ² /s, further preferably 15.8 to 25.2 mm ² /s, particularly preferably 17.7 to 21.6 mm ² /s, and most preferably 17.5 to 22.1 mm ² /s). When the kinematic viscosity at 40°C of the lubricating base oil is below the above upper limit, the low-temperature viscosity characteristics and fuel efficiency of the lubricating oil composition can be made better than when the kinematic viscosity exceeds the above upper limit. In addition, when the kinematic viscosity of the lubricating oil base oil at 40°C is above the above lower limit, the oil film formation at the lubricating position can be improved compared to the case where it is below the above lower limit, so that the lubricity is excellent, and the evaporation loss of the lubricating oil composition can be reduced, thereby reducing the consumption of the lubricating oil. In addition, in this specification, the so-called "kinematic viscosity at 40°C" means the kinematic viscosity at 40°C measured in accordance with JIS K 2283-2000.

The lubricating base oil preferably has a viscosity index of 100 or more (more preferably 105 or more, further preferably 110 or more, particularly preferably 115 or more, most preferably 120 or more). When the viscosity index is above the above lower limit, the viscosity-temperature characteristics and wear resistance of the lubricating oil composition can be improved compared to the case where the above lower limit is not reached, and the fuel consumption saving performance can be further improved. This can further reduce the evaporation loss of lubricating oil, thus reducing the consumption of lubricating oil. Furthermore, in this specification, the so-called "viscosity index" means the viscosity index measured in accordance with JIS K 2283-1993.

As the lubricating base oil, one with a NOACK evaporation amount at 250°C is preferably 30 mass% or less (more preferably 15 mass% or less). The lower limit of the NOACK evaporation amount of the lubricating base oil at 250°C is not particularly limited, but is usually 3 mass% or more. Furthermore, in this specification, the so-called "NOACK evaporation amount at 250°C" refers to the evaporation amount of the lubricating oil base oil or lubricating oil composition at 250°C measured in accordance with ASTM D 5800.

The lubricating oil base oil preferably has a flow point of -10°C or less (more preferably -12.5°C or less, and even more preferably -15°C or less). When the flow point is below the upper limit, the low-temperature fluidity of the lubricating oil composition as a whole can be improved compared to when the flow point exceeds the upper limit. In this specification, the so-called "flow point" means the flow point measured in accordance with JIS K 2269-1987.

The sulfur content of the above-mentioned lubricating oil base oil depends on the sulfur content of its raw material. For example, when using a raw material that is substantially free of sulfur, such as a synthetic wax component obtained by Fischer-Tropsch reaction, a lubricating oil base oil that is substantially free of sulfur can be obtained. Furthermore, in this specification, the so-called "sulfur content" means the sulfur content measured in accordance with JPI-5S-38. In addition, when using raw materials containing sulfur such as pine wax obtained in the refining process of lubricating oil base oil or microcrystalline wax obtained in the refining process, the sulfur content in the obtained lubricating oil base oil is usually 100 mass ppm or more. From the viewpoint of low sulfur content of the lubricating oil composition, the sulfur content of the lubricating base oil is preferably 100 mass ppm or less, more preferably 50 mass ppm or less, further preferably 10 mass ppm or less, and particularly preferably 5 mass ppm or less.

The content of the nitrogen component in the lubricating base oil is preferably 10 mass ppm or less (more preferably 5 mass ppm or less, further preferably 3 mass ppm or less). In this specification, the nitrogen content means the nitrogen content measured in accordance with JIS K 2609-1990.

The content of the lubricating oil base oil (all base oils) in the lubricating oil composition is preferably 70 to 95 mass % (more preferably 75 to 85 mass %) based on the total mass of the composition.

＜(B) Ingredient: Metal-based cleaner＞ In the present invention, the metal-based cleaning agent used as component (B) contains the following components: (B1) The calcium content based on the total mass of the composition (the calcium content derived from the component (B1) based on the total mass of the composition) is within the range of 1650 mass ppm or more and 2500 mass ppm or less. detergent, and (B2) The magnesium content based on the total mass of the composition (the content of magnesium derived from the component (B2) based on the total mass of the composition) is within the range of 20 mass ppm or more and 400 mass ppm or less. Detergent.

Here, "calcium-based cleaner" refers to a metal-based cleaner containing calcium as a metal, and "magnesium-based cleaner" refers to a metal-based cleaner containing magnesium as a metal. As such a metal-based cleaner, it is sufficient to appropriately select and use from among known metal-based cleaners (e.g., sulfonate cleaners, phenolate cleaners, salicylate cleaners, etc. containing calcium or magnesium as a metal) such that the amounts of calcium, magnesium, and boron are respectively in a desired content ratio. Here, regarding the “sulfonate cleaner”, “phenol salt cleaner” and “salicylate cleaner” exemplified as known metal-based cleaners, for example, those described in paragraphs [0038] to [0054] of Japanese Patent Publication No. 2020-76004 or those described in paragraphs [0043] to [0054] of International Publication No. 2018/212340 can be appropriately utilized.

<About component (B1)> The "calcium-based cleaner" used as component (B1) is a metal-based cleaner containing calcium as a metal, and its components contain at least a calcium-based cleaner containing boron and calcium (component (B1-1)). By making component (B1) contain component (B1-1), it is possible to effectively reduce friction and improve LSPI suppression capability compared to a case where component (B1-1) is not contained.

The above-mentioned "calcium-based detergent" used as component (B1) must contain the above-mentioned component (B1-1) containing boron and calcium, and may also contain other calcium-based detergents other than component (B1-1). As such a calcium-based detergent other than the component (B1-1), a known boron-free calcium-based cleanser (a known metal-based cleanser that does not contain boron and contains calcium as a metal) can be suitably used. Thus, as the said (B1) component, what consists only of (B1-1) component, or the mixture of (B1-1) component and a boron-free calcium-based detergent can be suitably utilized according to the purpose.

The type of calcium-based cleaner used as the component (B1) is not particularly limited, and examples thereof include sulfonate cleaners, phenol cleaners, salicylate cleaners, etc. containing calcium as a metal. Among such calcium-based cleaners, salicylate cleaners containing calcium as a metal are preferred from the viewpoint of friction reduction performance.

Such sulfonate cleaners containing calcium as metal (calcium sulfonate cleaners) are not particularly limited, and known ones can be appropriately used. As such calcium sulfonate cleaners, a more suitable example is a calcium salt of an alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound having a molecular weight of 300 to 1500 (preferably 400 to 1300). As the above-mentioned alkyl aromatic sulfonic acid, for example, petroleum sulfonic acid or synthetic sulfonic acid can be cited. Furthermore, as the above-mentioned petroleum sulfonic acid or synthetic sulfonic acid, known ones can be appropriately used. In addition, as the calcium sulfonate cleaner, known ones that can be used in lubricating oil compositions can be appropriately used.

The salicylate detergent (calcium salicylate detergent) containing calcium as a metal is not particularly limited, and known ones can be appropriately used. Examples of such a salicylate cleanser include a calcium salt of alkyl salicylic acid having 1 to 2 alkyl or alkenyl groups having 4 to 36 carbon atoms (more preferably 14 to 30 carbon atoms) as a substituent. and mixtures thereof. In addition, as the calcium salicylate detergent, known ones that can be used in lubricating oil compositions can be suitably used.

In addition, from the viewpoint of the friction reduction performance under particularly severe sliding conditions, the component (B1-1) (calcium-based cleaner containing boron and calcium) contained in the component (B1) is preferably a calcium-based cleaner containing calcium borate, more preferably a calcium-based cleaner obtained by superbasing calcium borate, and even more preferably a calcium salicylate cleaner obtained by superbasing calcium borate (calcium borate salicylate).

In addition, from the viewpoint of improving fuel economy performance according to application conditions, a mixture of component (B1-1) and a calcium-based cleaner (B1-2) containing calcium carbonate is preferably used as component (B1-2). Component (B1-2) (calcium-based cleaner containing calcium carbonate) is not particularly limited, but is more preferably a calcium-based cleaner obtained by superalkalinizing calcium carbonate, and particularly preferably a calcium salicylate cleaner obtained by superalkalinizing calcium carbonate.

When the component (B1) is a mixture of the component (B1-1) and a calcium-based cleaner other than the component (B1-1) (preferably the component (B1-2)), the content of the component (B1-1) in the component (B1) is not particularly limited, but the content of the component (B1-1) is preferably 30 to 100% by mass (more preferably 45 to 100% by mass, and further preferably 67 to 100% by mass) relative to the total amount of the component (B1). When the content of the component (B1-1) is greater than the above lower limit, the friction reduction performance under particularly severe sliding conditions can be further improved compared to a case where the content is less than the above lower limit.

Regarding the component (B1-1) used as the component (B1), the boron content in the component (B1-1) is preferably 1.0 to 5.0% by mass (more preferably, based on the total amount of the component (B1-1)). 1.3 to 4.5 mass%, more preferably 2.0 to 3.0 mass%). When the content of B in component (B1-1) is more than the above lower limit, the friction reducing performance and LSPI suppressing ability can be further improved compared to the case where it is less than the above lower limit. On the other hand, when the content is below the above upper limit In the case of exceeding the above upper limit, the stability of the lubricating oil composition can be improved.

The calcium-based cleaner used as component (B1) is preferably one in which the content of calcium (Ca) in each calcium-based cleaner contained in component (when component (B1) consists of only one calcium-based cleaner, the one calcium-based cleaner) is 2.0 to 11.5 mass % (more preferably 4.0 to 10.0 mass %, further preferably 5.7 to 7.2 mass %). When the calcium (Ca) content of each calcium-based cleaner is above the above lower limit, the friction loss under low temperature conditions can be further reduced compared to the case where it does not reach the above lower limit. On the other hand, when the calcium (Ca) content is below the above upper limit, the stability of the lubricating oil composition can be improved compared to the case where it exceeds the above upper limit.

The alkali value (TBN) of each calcium-based cleaning agent used as the component (B1) is not particularly limited, and is 50 to 500 mgKOH/g, more preferably 100 to 500 mgKOH/g, and particularly preferably 150 to 500 mgKOH/g in each calcium-based cleaning agent. When the alkali value of each calcium-based cleaning agent used as the component (B1) is above the lower limit, the acid neutralization performance can be improved compared to the case below the lower limit. On the other hand, when it is below the upper limit, the solubility of each additive in the lubricating oil composition can be improved compared to the case exceeding the upper limit. In addition, in this specification, the so-called "alkali value (TBN)" means the alkali value measured by the perchloric acid method according to JIS K2501.

(B1) The content of calcium (Ca _(B1) ) derived from the component (B1) based on the total mass of the composition needs to be 1650 mass ppm or more and 2500 mass ppm or less (more preferably 1650 mass ppm or more and 2200 mass ppm). ppm or less, more preferably 1,700 mass ppm or more and 1,900 mass ppm or less, particularly preferably 1,750 mass ppm or more and 1,900 mass ppm or less). When the calcium content (Ca _(B1) ) is above the above-mentioned lower limit, the cleaning performance can be improved compared to the case where it is less than the above-mentioned lower limit. On the other hand, when it is below the above-mentioned upper limit, the cleaning performance is better than when it exceeds the above-mentioned upper limit. Compared with the previous situation, both the LSPI suppression capability and the fuel consumption saving performance can be improved.

In addition, the content of boron (B _(B1) ) derived from component (B1) is preferably 50 mass ppm or more and 1000 mass ppm or less (based on the total mass of the composition (based on the total mass of the lubricating oil composition)). More preferably, it is not less than 200 mass ppm and not more than 700 mass ppm, further preferably not less than 400 mass ppm and not more than 700 mass ppm, still more preferably not less than 400 mass ppm and not more than 650 mass ppm). When the boron content (B _(B1) ) is above the above lower limit, the friction reducing performance and LSPI suppressing ability can be further improved compared to the case where it is less than the above lower limit. On the other hand, when it is below the above upper limit , the friction reduction performance can be further improved compared to the case where the above upper limit is exceeded.

Moreover, the content of component (B1) is preferably 1.5 to 3.5 mass% (more preferably 2.0 to 3.2 mass%, further preferably 2.4 to 2.9 mass%) based on the total amount of the lubricating oil composition. When the content of component (B1) is more than the above lower limit, the cleanability can be improved compared to the case where it is less than the above lower limit. On the other hand, when it is less than the above upper limit, it is better than when it exceeds the above upper limit. ratio, the friction reduction performance can be further improved.

Furthermore, the content of boron derived from the component (B1) (B _(B1) ) relative to the total amount of boron contained in the composition is preferably 50 mass % or more, more preferably 60 mass % to 100 mass %, and particularly preferably 70 mass % to 100 mass %. When the ratio of B _(B1) relative to the total amount of boron in the composition is greater than the above lower limit, the LSPI inhibitory ability can be further improved compared to a case where the ratio is less than the above lower limit.

In addition, the content of calcium derived from the component (B1) (Ca _(B1) ) relative to the total amount of calcium contained in the composition is preferably 50 mass % or more, more preferably 75 mass % to 100 mass %, and particularly preferably 90 mass % to 100 mass %. When the ratio of Ca _(B1) relative to the total amount of calcium in the composition is greater than the above lower limit, the LSPI inhibitory ability can be further improved compared to the case where it does not reach the above lower limit.

Furthermore, the content of boron derived from component (B1) based on the total mass of the composition (B _(B1) ), and the content of calcium derived from component (B1) based on the total mass of the composition ( Ca _(B1) ) can be measured by the measurement method specified in JPI-5S-38.

<About component (B2)> The "magnesium-based cleaner" used as component (B2) is not particularly limited, and a known metal-based cleaner containing magnesium as a metal can be appropriately used. Examples of such magnesium-based cleaners include sulfonate cleaners, phenol salt cleaners, and salicylate cleaners containing magnesium as a metal. Among such magnesium-based cleaners, sulfonate cleaners containing magnesium as a metal and salicylate cleaners containing magnesium as a metal are preferred from the perspective of friction reduction performance.

Such a sulfonate detergent containing magnesium as a metal (magnesium sulfonate detergent) is not particularly limited, and known ones can be appropriately used. Suitable examples of such a magnesium sulfonate detergent include magnesium alkyl aromatic sulfonate obtained by sulfonating an alkyl aromatic compound with a molecular weight of 300 to 1500 (more preferably 400 to 1300). salt. Examples of the alkyl aromatic sulfonic acid include petroleum sulfonic acid and synthetic sulfonic acid. Furthermore, as the above-mentioned petroleum sulfonic acid or synthetic sulfonic acid, known ones can be appropriately used. In addition, as the magnesium sulfonate detergent, known ones that can be used in lubricating oil compositions can be suitably used.

The salicylate cleaner containing magnesium as a metal (magnesium salicylate cleaner) is not particularly limited, and known ones can be appropriately used. Examples of such salicylate cleaners include magnesium salts of alkyl salicylic acids having 1 to 2 alkyl or alkenyl groups with 4 to 36 carbon atoms (preferably 14 to 30) as substituents and mixtures thereof. In addition, known ones that can be used in lubricating oil compositions can be appropriately used as magnesium salicylate cleaners.

In addition, as the magnesium-based cleaner, a magnesium-based cleaner containing magnesium carbonate is preferred. The magnesium-based cleaner containing magnesium carbonate is not particularly limited, and a magnesium-based cleaner peralkalized with magnesium carbonate is more preferred, and in particular, from the viewpoint of suppressing the alkali value consumption when water is mixed (the alkali value consumption caused by the coarsening, sedimentation or precipitation of the magnesium-based cleaner under the condition of adding water), a magnesium sulfonate cleaner peralkalized with magnesium carbonate is particularly preferred.

The content of magnesium (Mg) in the component (B2) is preferably 6.0 to 10.0 mass% (more preferably 7.5 to 9.5 mass%, further preferably 7.5 to 9.1 mass%) based on the total amount of the component (B2). . When the magnesium content in component (B2) is above the above lower limit, the viscous resistance can be reduced compared to the case where it is less than the above lower limit. On the other hand, when it is below the above upper limit, the viscous resistance can be reduced. Compared with the above upper limit, the stability of the lubricating oil composition can be improved.

The alkali value (TBN) of each magnesium-based cleaning agent used as component (B2) is not particularly limited, but is preferably 50 to 500 mgKOH/g, more preferably 100 to 500 mgKOH/g, and particularly preferably 150 to 500 mgKOH/g. When the alkali value of component (B2) is above the lower limit, the viscosity resistance can be further reduced compared to the case below the lower limit. On the other hand, when the alkali value is below the upper limit, the stability of the lubricating oil composition can be improved compared to the case exceeding the upper limit.

(B2) The content of magnesium (Mg _(B2) ) derived from the component (B2) based on the total mass of the composition needs to be 20 mass ppm or more and 400 mass ppm or less (more preferably 20 mass ppm or more and 300 mass ppm). ppm or less, more preferably 100 mass ppm or more and 300 mass ppm or less, particularly preferably 100 mass ppm or more and 200 mass ppm or less). When the content of magnesium (Mg _(B2) ) is above the above lower limit, the LSPI inhibitory ability can be improved compared to the case where it is less than the above lower limit. On the other hand, when it is below the above upper limit, the LSPI inhibitory ability can be improved compared to when it is below the above upper limit. Compared with the upper limit case, the fuel consumption performance can be improved. In addition, the content of magnesium (Mg _(B2) ) derived from component (B2) based on the total mass of the composition can be measured by the measuring method described in JPI-5S-38.

Moreover, the content of component (B2) is preferably 0.01 to 0.60 mass % (more preferably 0.01 to 0.40 mass %, further preferably 0.10 to 0.27 mass %) based on the total amount of the lubricating oil composition. When the content of component (B2) is more than the above lower limit, the acid neutralizing performance can be improved compared to the case where it is less than the above lower limit. On the other hand, when it is less than the above upper limit, it can be improved compared to the case where it exceeds the above upper limit. Compared with the previous case, the friction reduction performance can be further improved.

In addition, the content of magnesium derived from the component (B2) (Mg _(B2) ) relative to the total amount of magnesium contained in the composition is preferably 50 mass % or more, more preferably 75 mass % to 100 mass %, and particularly preferably 90 mass % to 100 mass %. When the ratio of Mg _(B2) relative to the total amount of magnesium in the composition is greater than the above lower limit, the fuel consumption performance can be further improved compared to the case where it does not reach the above lower limit.

Component (B) may also contain other metal-based cleaners other than component (B1) and component (B2) if necessary. Furthermore, the ratio of the total amount of component (B1) and component (B2) to the total amount of component (B) is preferably 50 to 100 mass % (more preferably 75 to 100 mass %, especially 90 to 100 mass%). When the ratio of the total amount of the component (B1) to the component (B2) is equal to or higher than the above lower limit, the LSPI suppressing ability and friction reducing performance can be further improved compared to the case where the ratio does not reach the above lower limit. There are no particular restrictions on the metal-based cleaning agents other than the component (B1) and the component (B2), and known metal-based cleaning agents can be appropriately used. Furthermore, from the viewpoint of balancing LSPI inhibitory ability and friction reducing performance, component (B) is more preferably a mixture of component (B1) and component (B2).

In addition, the content of component (B) is preferably 1.0 to 4.0 mass % (more preferably 2.2 to 3.0 mass %, and further preferably 2.6 to 3.0 mass %) based on the total amount of the lubricating oil composition. When the content of component (B) is above the lower limit, the acid neutralization performance can be improved compared to the case below the lower limit, while when it is below the upper limit, the friction reduction performance can be further improved compared to the case exceeding the upper limit.

Furthermore, in the lubricating oil composition for an internal combustion engine of the present invention, when the content (mass ratio) of boron in the component (B1) based on the total mass of the composition is expressed as B _(B1) and the content (mass ratio) of calcium in the component (B1) based on the total mass of the composition is expressed as Ca _(B1) , the ratio of B _(B1) to Ca _(B1) (B _(B1) /Ca _(B1) ) is not less than 0.15 and not more than 0.35 (preferably not less than 0.21 and not more than 0.30, and particularly preferably not less than 0.26 and not more than 0.29). When B _(B1) /Ca _(B1) is above the above lower limit, the LSPI suppression capability can be improved compared to the case where it does not reach the above lower limit, thereby achieving both excellent LSPI suppression capability and excellent fuel consumption performance. On the other hand, when it is below the above upper limit, the friction coefficient can be made lower than the case where it exceeds the above upper limit, thereby achieving both excellent LSPI suppression capability and excellent fuel consumption performance.

In the lubricating oil composition for an internal combustion engine of the present invention, when the content (mass ratio) of boron in the component (B1) based on the total mass of the composition is denoted as B _(B1) , the content (mass ratio) of calcium in the component (B1) based on the total mass of the composition is denoted as Ca _(B1) , and the content (mass ratio) of magnesium in the component (B2) based on the total mass of the composition is denoted as Mg _(B2) , the ratio of B _(B1) to the total amount of Ca _(B1) and Mg _(B2) (Ca _(B1) +Mg _(B2) ) (B _(B1) / [Ca _(B1) +Mg _(B2) ]) is 0.13 to 0.29 (more preferably 0.23 to 0.29, and even more preferably 0.25 to 0.29). When B _(B1) /[Ca _(B1) +Mg _(B2) ] is above the above lower limit, the LSPI suppression capability can be improved compared to the case below the above lower limit. On the other hand, when it is below the above upper limit, the fuel consumption performance can be improved compared to the case exceeding the above upper limit.

Furthermore, in the lubricating oil composition for an internal combustion engine of the present invention, when the content (mass ratio) of boron in the component (B1) based on the total mass of the composition is represented by B _(B1) and the total amount of calcium in the composition based on the total mass of the composition (content of all calcium: mass ratio) is represented by Ca, the ratio of B _(B1) to Ca (B _(B1) /Ca) is 0.15 to 0.35 (more preferably 0.21 to 0.31, and particularly preferably 0.26 to 0.30). When B _(B1) /Ca is above the lower limit, the LSPI suppression capability can be further improved compared to the case below the lower limit, and when it is below the upper limit, the fuel consumption performance can be further improved compared to the case exceeding the upper limit.

In the lubricating oil composition for internal combustion engines of the present invention, the boron content (mass ratio) in component (B1) based on the total mass of the composition is expressed as B _(B1). The total amount of calcium in the composition based on the total mass of the composition (all calcium content: mass ratio) is expressed as Ca, and the total amount of magnesium in the composition based on the total mass of the composition (all magnesium content: mass ratio) ) is expressed as Mg, the ratio (B ( _{B1 ) / [Ca + Mg]) of B (B1} ) to the total amount of Ca and Mg (Ca + Mg) is preferably 0.13 or more and 0.29 or less (more preferably 0.23 or more and 0.29 or less) , especially preferably above 0.25 and below 0.29). When B _(B1) /[Ca+Mg] is above the above lower limit, the LSPI suppression capability can be further improved compared to when it is below the above lower limit. On the other hand, when it is below the above upper limit, it is better than when it exceeds the above limit. Compared with the upper limit case, the fuel consumption performance can be further improved.

Furthermore, the preparation method of the metal-based detergent used as component (B) is not particularly limited, and known methods can be appropriately used.

In addition, the lubricating oil composition for internal combustion engines of the present invention may contain, in addition to the components (A) and (B) (including the components (B1) and (B2)), known additives commonly used in lubricating oil compositions for internal combustion engines according to the purpose, to further improve its performance. The components suitable for use as such additives are described below.

<Component (C): Poly(meth)acrylate viscosity index enhancer> In order to further improve fuel efficiency, the lubricating oil composition for internal combustion engines of the present invention preferably contains (C) poly(meth)acrylate viscosity index enhancer. Here, as the "poly(meth)acrylate viscosity index enhancer", the known poly(meth)acrylate compounds used as viscosity index enhancers can be appropriately used (for example, the "viscosity index enhancer" described in International Publication No. 2019/221295, the "poly(meth)acrylate compound" described in Japanese Patent Publication No. 2018-177986, and the Japanese Patent Publication No. 2017-101211). "Comb polymer" described in the gazette, "viscosity index enhancer" described in International Publication No. 2016/159006, "viscosity index enhancer" described in International Publication No. 2017/099052, "viscosity index enhancer" described in Japanese Patent Laid-Open No. 2017-110196, "(co)polymer (A)" described in Japanese Patent Laid-Open No. 2017-110196, etc.).

The poly(meth)acrylate polymer used as the component (C) is not particularly limited in structure and may be a so-called linear poly(meth)acrylate polymer or a so-called comb-shaped poly(meth)acrylate polymer. Among them, the component (C) is more preferably a comb-shaped poly(meth)acrylate polymer from the viewpoint of improving the fuel consumption performance along with the improvement of the viscosity-temperature characteristics and the oil film forming property. Moreover, the poly(meth)acrylate viscosity index improver is particularly preferably a comb-shaped poly(meth)acrylate polymer. As such a comb-like poly(meth)acrylate polymer, a known poly(meth)acrylate polymer having a so-called comb-like structure (for example, the “comb-like polymer” described in Japanese Patent Laid-Open No. 2017-101211, the “comb-like poly(meth)acrylate” described in Japanese Patent Laid-Open No. 2018-177986, the “comb-like poly(meth)acrylate” described in International Publication No. 2016/159006, the “viscosity index enhancer” described in Japanese Patent Laid-Open No. 2017-110196, the “(co)polymer (A)” described in Japanese Patent Laid-Open No. 2017-110196, etc.) can be appropriately utilized.

As such a comb-shaped poly(meth)acrylate polymer, a poly(meth)acrylate polymer having a comb-shaped structure, which is a copolymer of (meth)acrylate and (meth)acrylate macromonomer, can be appropriately used. Moreover, such a comb-shaped poly(meth)acrylate polymer can also be a copolymer of (meth)acrylate, (meth)acrylate macromonomer, and other monomers (such as ethylene, styrene, or 1-butene). Furthermore, in this specification, the so-called "(meth)acrylate" means acrylate and/or methacrylate.

In addition, as the comb-shaped poly(meth)acrylate-based polymer, suitable ones include (meth)acrylate represented by the following formula (1) (hereinafter, abbreviated to "monomer (M) as appropriate"). -1)") A copolymer with a (meth)acrylate macromonomer represented by the following formula (2) (hereinafter, simply referred to as "macromonomer (M-2)" as appropriate).

[Chemical 1]

[In formula (1), ^R1 represents a hydrogen atom or a methyl group, and ^R2 represents a linear or branched alkyl group having 2 to 10 carbon atoms]

[Chemistry 2]

[In formula (2), ^R3 represents a hydrogen atom or a methyl group, and ^R4 represents a alkyl group having 12 to 24 carbon atoms]

^R2 in formula (1) is a linear or branched alkyl group (preferably an alkyl group) having a carbon number of 2 to 10. The carbon number of the alkyl group selected as ^R2 is preferably 4 to 10 (more preferably 4 to 8, and particularly preferably 4 to 6).

In addition, the carbon number of the alkyl group selected as ^R4 in formula (2) is 12 to 24 (more preferably 12 to 20, and particularly preferably 12 to 18). When the carbon number is above the lower limit, a high viscosity index can be achieved, and if it is below the upper limit, good flow under low temperature conditions can be achieved. Furthermore, the alkyl group may be a linear chain or a branched chain. Furthermore, as the macromonomer (M-2), for example, a macromonomer derived from a hydrogenated product of a polyolefin obtained by copolymerizing butadiene and isoprene can be used. In addition, as such a macromonomer (M-2), for example, a known macromonomer (for example, the macromonomer described in Japanese Patent Publication No. 2018-177986, or the "monomer (a)" described in Japanese Patent Publication No. 2017-110196, etc.) can also be appropriately utilized.

In the copolymer of monomer (M-1) and macromonomer (M-2), the copolymerization molar ratio of the monomers is not particularly limited, and the monomer (M-1):monomer (M-2) is preferably about 20:80 to 90:10 (more preferably 30:70 to 80:20, and further preferably 40:60 to 70:30).

In addition, the weight average molecular weight (Mw) of the poly(meth)acrylate polymer (preferably a comb-shaped poly(meth)acrylate polymer) contained in the poly(meth)acrylate viscosity index enhancer is preferably 100,000 to 1,000,000 (more preferably 300,000 to 1,000,000, and further preferably 600,000 to 800,000). When the weight average molecular weight is above the lower limit, the viscosity index when dissolved in the lubricating oil base oil can be improved compared to the case below the lower limit, and the fuel saving performance and low-temperature viscosity characteristics can be improved. On the other hand, when the weight average molecular weight is below the upper limit, the fuel saving performance and low-temperature viscosity characteristics can be improved compared to the case exceeding the upper limit, and the shear stability, solubility in the lubricating oil base oil, and storage stability can be improved.

Furthermore, when (C) the poly(meth)acrylate viscosity index improver contains a comb-shaped poly(meth)acrylate-based polymer, the content of the comb-shaped poly(meth)acrylate-based polymer is relatively The total amount of component (C) is preferably 30 mass% or more (more preferably 50 to 100 mass%, further preferably 95 to 100 mass%, particularly preferably 98 to 100 mass%). When the content of the comb-shaped poly(meth)acrylate polymer in component (C) is more than the above lower limit, it can improve the viscosity-temperature characteristics and oil film formation compared to the case where it does not reach the above lower limit. to further improve fuel consumption performance. Furthermore, as the component (C), from the viewpoint of improving the viscosity-temperature characteristics and oil film formation properties, it is more preferable to use one composed only of a comb-shaped poly(meth)acrylate polymer.

Moreover, the content of component (C) is preferably 5 to 15 mass % (more preferably 7 to 11 mass %, further preferably 9 to 11 mass %) based on the total amount of the lubricating oil composition. When the content of component (C) is more than the above lower limit, compared with the case where it is less than the above lower limit, the viscosity-temperature characteristics can be improved, and the wear resistance can be improved by the formation of an oil film. On the other hand, because of the above When it is below the upper limit, compared with when it exceeds the upper limit, fuel-saving performance can be further improved by suppressing excessive viscosity increase.

The method for preparing the poly(meth)acrylate polymer used in the component (C) is not particularly limited, and a known method can be appropriately adopted. As such a preparation method, for example, a method of obtaining a poly(meth)acrylate polymer by subjecting a monomer (M-1), a macromonomer (M-2), and other monomers used as required to free radical solution polymerization in the presence of a polymerization initiator (such as benzoyl peroxide, etc.) can be adopted.

＜(D)Component: Ashless dispersant＞ In the case where metal powder produced due to abrasion during use is highly dispersed, can improve wear resistance, and can improve oxidation stability, the lubricating oil composition for internal combustion engines of the present invention preferably further contains (D) ashless dispersion agent. As the component (D), compounds known to be used as ashless dispersants in the field of lubricating oil compositions (for example, the "nitrogen-containing ashless dispersant" described in International Publication No. 2019/221295 and Japanese Patent No. Ashless dispersants described in Japanese Patent Application Publication No. 2003-155492, Japanese Patent Application Publication No. 2020-76004, International Publication No. 2013/147162, etc.).

Examples of the ashless dispersant include monosuccinimide or disuccinimide having at least one linear or branched alkyl or alkenyl group in the molecule, benzylamine having at least one alkyl or alkenyl group in the molecule, or polyamine having at least one alkyl or alkenyl group in the molecule, or modified products thereof obtained using boron compounds, carboxylic acids, phosphoric acids, etc. In the component (D), the linear or branched alkyl or alkenyl group is preferably a linear or branched alkyl or alkenyl group having 40 to 400 carbon atoms (more preferably 60 to 350 carbon atoms).

From the viewpoint of imparting better dispersibility to metal powders, etc., as the component (D), it is preferable to use (D1) boronated succinimide (boron-modified compounds of the above-mentioned monosuccinimide or bissuccinimide, etc.), (D2) non-boronated succinimide (the above-mentioned monosuccinimide or bissuccinimide, etc.), and mixtures thereof.

As the (D1) component and the (D2) component, a boronated succinimide compound or a non-boronated succinimide compound known as an ashless dispersant can be appropriately used. As the (D1) component and the (D2) component, it is preferred that the content of nitrogen atoms is 0.5 to 3.0% by mass based on the total amount of the component (the (D1) component or the (D2) component). As the (D1) component, it is preferred that the content of boron is 0.1 to 5.0% by mass (more preferably 0.1 to 3.0% by mass) based on the total amount of the (D1) component. Furthermore, the (D1) component and the (D2) component preferably have a weight average molecular weight of 1,000 to 20,000 (more preferably 2,000 to 20,000, and more preferably 4,000 to 15,000). In addition, the component (D) may be used alone or in combination of two or more.

When the lubricating oil composition of the present invention contains component (D), the content of component (D) is not particularly limited. It is preferably 0.1 to 5.0 mass % (based on the total amount of the lubricating oil composition). More preferably, it is 1.0 to 2.5% by mass). By setting the content of component (D) within the above range, the dispersion performance when insoluble components are generated can be improved.

Furthermore, when the component (D) includes the component (D1), the content of boron derived from the component (D1) (B _(D1) ) is preferably 90 mass % or less (more preferably 70 mass % or less, and further preferably 27 mass % or less) relative to the total amount of boron contained in the composition. When the ratio of B _(D1) to the total amount of boron in the composition is below the upper limit, the generation of excessive ash can be suppressed compared to the case where it exceeds the upper limit.

＜(E) Ingredient: Antioxidant＞ The lubricating oil composition of the present invention preferably further contains (E) an antioxidant in order to improve the oxidation stability. The component (E) is not particularly limited, and those known as antioxidants in the field of lubricating oil compositions can be suitably used. Examples thereof include: (E1) phenolic antioxidant, (E2) amine antioxidant, (E3) Metal-based antioxidants (copper-based antioxidants, molybdenum-based antioxidants, etc.), etc.

As the component (E1), well-known ones can be appropriately used. For example, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 3-(3,5-di -Hindered phenol compounds and bisphenol compounds such as methyl tert-butyl-4-hydroxyphenyl)propionate.

As the component (E2), for example, compounds known as amine antioxidants such as aromatic amine antioxidants and hindered amine antioxidants can be appropriately used (for example, compounds illustrated in International Publication No. 2020/095970, etc.) . As the aromatic amine antioxidant, alkylated diphenylamine and alkylated phenyl-α-naphthylamine are suitably used. As the hindered amine antioxidant, for example, a compound having a 2,2,6,6-tetraalkylpiperidine skeleton (2,2,6,6-tetraalkylpiperidine derivative) or the like is suitably used. As the above-mentioned amine-based antioxidant, aromatic amine-based antioxidants are more preferably used.

Examples of the component (E3) include: oxymolybdenum sulfide or an alkylamine complex of oxymolybdenum, oxymolybdenum sulfide or an alkenyl succinimide complex of oxymolybdenum, and dithiocarbamate oxysulfide. Molybdenum, molybdenum dithiophosphate molybdenum oxysulfide and other organic molybdenum antioxidants, etc. Among such molybdenum-based antioxidants, oxymolybdenum sulfide or oxymolybdenum-di(tridecyl)amine is more preferred in terms of suppressing viscosity increase, easily maintaining fuel-saving performance for a long time, and having better high-temperature cleaning properties. complex, oxymolybdenum sulfide or oxymolybdenum-alkenyl succinimide complex.

In addition, the component (E) may be used alone or in combination of two or more. Furthermore, as the component (E), the component (E1), the component (E2), and the component (E3) may be used in appropriate combination. In particular, in order to suppress the oxidative degradation of the lubricating oil composition for a long period of time, it is preferred to use the component (E2) in combination with the component (E3).

When the lubricating oil composition for internal combustion engines of the present invention contains component (E), the content of component (E) is preferably 1.5 mass % to 2.5 mass % (more preferably 1.7 mass % to 2.0 mass %) based on the total amount of the lubricating oil composition. By setting the content of component (E) within the above range, the solubility of component (E) can be maintained and the deterioration inhibition of the lubricating oil composition can be improved.

Furthermore, when the lubricating oil composition for internal combustion engines of the present invention contains component (E1), the content of component (E1) is preferably 2.0 mass % or less (more preferably 0.5 mass % or less) based on the total amount of the lubricating oil composition. By setting the content of component (E1) within the above range, the solubility of the component can be maintained and the deterioration inhibition of the lubricating oil composition can be improved.

Furthermore, when the lubricating oil composition for internal combustion engines of the present invention contains the component (E2), the content of the component (E2) is preferably 1.3 mass % or more and 2.3 mass % or less (based on the total amount of the lubricating oil composition). More preferably, it is 1.5 mass % or more and 1.9 mass % or less). By setting the content of the component (E2) within the above range, the solubility of the component can be maintained and the deterioration inhibitory properties of the lubricating oil composition can be improved.

Furthermore, when the lubricating oil composition for internal combustion engines of the present invention contains the component (E3), the content of the component (E3) is preferably 0.3% by mass or less (more preferably 0.1%) based on the total amount of the lubricating oil composition. Mass% or more and 0.2 mass% or less). By setting the content of the component (E3) within the above range, the solubility of the component can be maintained and the deterioration inhibitory properties of the lubricating oil composition can be improved.

＜(F) Molybdenum-based friction modifier＞ The lubricating oil composition for an internal combustion engine of the present invention preferably contains (F) a molybdenum-based friction modifier (oil-soluble organic molybdenum compound). As such a molybdenum-based friction modifier, those known as molybdenum-based friction modifiers in the field of lubricating oil compositions can be suitably used.

In addition, as the component (F), from the viewpoint of reducing friction under boundary lubrication conditions, molybdenum dithiocarbamate (molybdenum dithiocarbamate sulfide or molybdenum oxycarbamate dithiocarbamate sulfide) is more preferred. . As the molybdenum dithiocarbamate (MoDTC), for example, a compound represented by the following general formula (3) is suitably used.

[Chemistry 3]

[In formula (3), R ¹⁰ to R ¹³ each independently represent an alkyl group having 2 to 24 carbon atoms or an (alkyl)aryl group having 6 to 24 carbon atoms, and Y ¹ to Y ⁴ each independently represents a sulfur atom or Oxygen atom, at least one of Y ¹ to Y ⁴ represents a sulfur atom]

R ¹⁰ to R ¹³ in the above general formula (3) may be the same or different, and represent an alkyl group with 2 to 24 carbon atoms or an (alkyl)aryl group with 6 to 24 carbon atoms (preferably, alkyl group with 4 carbon atoms). ~13 alkyl group or (alkyl)aryl group with 10-15 carbon atoms). The alkyl group optionally used as R ¹⁰ to R ¹³ may be any one of primary alkyl group, secondary alkyl group and tertiary alkyl group, and may be straight chain or branched chain. In addition, the "(alkyl)aryl group" mentioned here means "aryl group or alkylaryl group". In alkylaryl groups, the substitution position of the alkyl group in the aromatic ring is arbitrary. In addition, Y ¹ to Y ⁴ in the above general formula (3) are each independently a sulfur atom or an oxygen atom, and at least one of Y ¹ to Y ⁴ is a sulfur atom.

Examples of the oil-soluble organic molybdenum compound other than the molybdenum dithiocarbamate include: molybdenum dithiophosphate; molybdenum compounds (for example, molybdenum dioxide, molybdenum trioxide and other molybdenum oxides, orthomolybdic acid, Molybdates such as paramolybdic acid and (poly)molybdic acid sulfide, metal salts of these molybdic acids, ammonium salts and other molybdates, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, molybdenum polysulfide and other molybdenum sulfides, molybdenum sulfide Acid, metal salt or amine salt of molybdic acid sulfide, molybdenum chloride and other molybdenum halides, etc.) and sulfur-containing organic compounds (for example, (thio)xanthate alkyl ester, thiadiazole, mercaptothiadiazole, thio Carbonate, tetrahydrocarbylthiuram disulfide, bis(di(thio)hydrocarbyl dithiophosphonate) disulfide, organic (poly)sulfide, sulfide ester, etc.) or complexes of other organic compounds, etc. ; and sulfur-containing organic molybdenum compounds such as complexes of the above-mentioned molybdenum sulfide, molybdic acid sulfide and other sulfur-containing molybdenum compounds and alkenyl succinimide. Furthermore, the organic molybdenum compound may be a mononuclear molybdenum compound, or a multinuclear molybdenum compound such as a dinuclear molybdenum compound or a trinuclear molybdenum compound.

Furthermore, as the oil-soluble organic molybdenum compound other than the above-mentioned molybdenum dithiocarbamate, a sulfur-free organic molybdenum compound may be used. Examples of the sulfur-free organic molybdenum compound include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, and molybdenum salts of alcohols. Among them, molybdenum-amine complexes, molybdenum salts of organic acids, and molybdenum salts of alcohols are preferred.

The content of the component (F) in the lubricating oil composition is preferably such that the molybdenum content is 100 to 2000 mass ppm (more preferably 300 to 1500 mass ppm, further preferably 500 to 1200 mass ppm, and particularly preferably 700 to 1000 mass ppm) based on the total amount of the lubricating oil composition. When the content of the component (F) is above the lower limit, the fuel consumption performance and the LSPI suppression capability can be further improved. In addition, when the content of the component (F) is below the upper limit, the storage stability of the lubricating oil composition can be improved.

<(G) Anti-wear agent> The lubricating oil composition for internal combustion engines of the present invention preferably contains (G) an anti-wear agent. The anti-wear agent is not particularly limited, and known compounds used as anti-wear agents in lubricating oil compositions can be used. As the anti-wear agent, for example, sulfur-based, phosphorus-based, sulfur-phosphorus-based anti-wear agents can be used. Specifically, anti-wear agents include: phosphites, thiophosphites, dithiophosphites, trithiophosphites, phosphates, thiophosphates, dithiophosphates, trithiophosphates, their amine salts, their metal salts, their derivatives, dithiocarbamates, zinc dithiocarbamates, disulfides, polysulfides, olefin sulfides, sulfide oils, etc.

Among these anti-wear agents, a phosphorus-based anti-wear agent is preferred, and a phosphorus-based anti-wear agent containing zinc is more preferred. Among them, zinc dialkyldithiophosphate represented by the following formula (4) is particularly preferred. (ZnDTP).

[Chemistry 4]

[In formula (4), R ¹⁴ to R ¹⁷ each independently represent a linear or branched alkyl group having 1 to 24 carbon atoms]

R ¹⁴ to R ¹⁷ in the above general formula (4) each independently represent a linear or branched alkyl group having 1 to 24 carbon atoms, and may also be a combination of different groups. Furthermore, the number of carbon atoms in R ¹⁴ to R ¹⁷ is preferably 3 or more, more preferably 12 or less, and more preferably 8 or less. Moreover, R ¹⁴ to R ¹⁷ may be any one of a primary alkyl group, a secondary alkyl group and a tertiary alkyl group, but a primary alkyl group or a secondary alkyl group or a combination thereof is preferred, and a primary alkyl group is even more preferred. The molar ratio between the base and the secondary alkyl group (primary alkyl group: secondary alkyl group) is 0:100~30:70. The ratio can be the combination ratio of the alkyl chains in the molecule, or the mixing ratio of ZnDTP with only primary alkyl groups and ZnDTP with only secondary alkyl groups. By mainly using secondary alkyl groups, fuel consumption performance can be further improved. In addition, the method for producing ZnDTP is not particularly limited, and known methods can be appropriately used. For example, the following method can be used: reacting an alcohol having an alkyl group corresponding to R ¹⁴ to R ¹⁷ and phosphorus pentasulfide to synthesize dithiophosphate, and It is synthesized by neutralizing it with zinc oxide.

The content of the anti-wear agent is based on the total amount of the lubricating oil composition, and is preferably 0.1 to 5.0 mass% or less (more preferably 0.5 to 3.0 mass% or less). If the content of the anti-wear agent is within the above numerical range, sufficient anti-wear effect can be obtained.

＜(H) Pour point depressant＞ The lubricating oil composition for internal combustion engines of the present invention preferably contains (H) a pour point depressant. Such pour point depressant is not particularly limited, and known pour point depressants used in lubricating oil compositions can be appropriately utilized. Examples of such a pour point depressant include poly(meth)acrylate, ethylene-vinyl acetate copolymer, and the like. Among them, polymethacrylate is preferred. In addition, as the poly(meth)acrylate (more preferably polymethacrylate) used as the pouring point depressant, from the viewpoint of the pouring point depressing effect and shear stability, it is preferable that the weight average molecular weight is 20,000 to 100,000 (better, 20,000 to 80,000).

The pour point depressant may be used alone or in combination of two or more. When a pour point depressant is used, its content is preferably 0.01 to 1.0 mass % (more preferably 0.03 to 0.6 mass %) based on the total amount of the lubricating oil composition.

<(I) Other components> The lubricating oil composition for internal combustion engines of the present invention may further contain other additives that can be used in lubricating oil compositions in addition to the above-mentioned components. Such other components are not particularly limited, and examples thereof include: defoaming agents, anti-rust agents, anti-emulsifiers, metal deactivators, etc. Such other components can be appropriately used by known ones. For example, as defoaming agents, polysilicone oils having a kinematic viscosity of 1,000 to 100,000 ^mm2 /s at 25°C, alkenyl succinic acid derivatives, esters of polyhydroxy fatty alcohols and long-chain fatty acids, methyl salicylate, and o-hydroxybenzyl alcohol can be exemplified. The content of such other components is not particularly limited as long as each component is appropriately designed to be the optimal amount according to the application, but it is preferably set to about 0.001 to 5 mass % based on the total amount of the lubricating oil composition. In addition, the content of each component used as component (I) is preferably 0.001 to 0.05 mass parts when the total mass of the components in the lubricating oil composition other than the component is set to 100 mass parts.

[About lubricating oil composition] In the lubricating oil composition for internal combustion engines of the present invention, the boron content based on the total mass of the composition (the boron content based on the total mass of the lubricating oil composition) is 1000 mass ppm or less (more preferably 200 mass ppm or more and 700 mass ppm or less, and further preferably 400 mass ppm or more and 650 mass ppm or less). By setting the boron content based on the total mass of the composition to below the above upper limit, the friction reduction performance can be improved compared to the case where it exceeds the above upper limit. On the other hand, when it is above the above lower limit, the LSPI suppression ability can be improved compared to the case where it does not reach the above lower limit.

In the lubricating oil composition for internal combustion engines of the present invention, the calcium content based on the total amount of the lubricating oil composition is preferably 1650 mass ppm or more and 2500 mass ppm or less (more preferably 1700 mass ppm or more and 1900 mass ppm or less, and further preferably 1750 mass ppm or more and 1900 mass ppm or less). By setting the calcium content based on the total amount of the composition to be below the upper limit, LSPI suppression capability and friction reduction performance can be achieved as compared to a case where the content exceeds the upper limit. On the other hand, when the content is above the lower limit, the detergency can be improved by improving the acid neutralization as compared to a case where the content is below the lower limit.

In the lubricating oil composition for internal combustion engines of the present invention, the magnesium content based on the total amount of the lubricating oil composition is preferably 20 mass ppm or more and 400 mass ppm or less (more preferably 20 mass ppm or more and 300 mass ppm or less), and further Preferably it is 100 mass ppm or more and 200 mass ppm or less). By setting the magnesium content based on the total amount of the composition to less than the above upper limit, the friction reducing performance can be improved compared to the case where it exceeds the above upper limit. On the other hand, when it is above the above lower limit, Compared with the case where the above lower limit is not reached, the acid neutralizing performance can be improved.

In the lubricating oil composition for internal combustion engines of the present invention, when molybdenum is included in the composition, the content of molybdenum based on the total amount of the lubricating oil composition is preferably 100 mass ppm to 1200 mass ppm (more preferably 700 mass ppm to 1000 mass ppm). By setting the content of molybdenum based on the total amount of the composition within the above range, the solubility of the additive in the composition can be maintained and the friction reduction performance can be further improved.

In the lubricating oil composition for internal combustion engines of the present invention, when phosphorus is contained in the composition, the phosphorus content based on the total amount of the lubricating oil composition is preferably 600 mass ppm or more and 800 mass ppm or less (more preferably 700 mass ppm or more and 800 mass ppm or less). By setting the phosphorus content based on the total amount of the composition within the above range, excessive catalyst poisoning can be avoided while taking into account both friction reduction performance and anti-wear performance.

In the lubricating oil composition for internal combustion engines of the present invention, when sulfur is contained in the composition, the sulfur content based on the total amount of the lubricating oil composition is preferably 500 mass ppm to 3000 mass ppm (more preferably 1000 mass ppm to 2700 mass ppm). By setting the sulfur content based on the total amount of the composition within the above range, the burn-in resistance can be improved.

In the lubricating oil composition for internal combustion engines of the present invention, when zinc is contained in the composition, the content of zinc based on the total amount of the lubricating oil composition is preferably 500 mass ppm to 1300 mass ppm (more preferably 700 mass ppm to 900 mass ppm). By setting the content of zinc based on the total amount of the composition within the above range, the anti-wear property can be improved.

Furthermore, the contents of boron, calcium, magnesium, molybdenum, zinc, sulfur and phosphorus in the lubricating oil composition can be determined according to JPI-5S-62.

In the lubricating oil composition for internal combustion engines of the present invention, the ratio of the content of boron based on the total amount of the lubricating oil composition to the content of calcium based on the total amount of the lubricating oil composition (mass ratio: [boron]/[calcium]) is preferably 0.15 to 0.35 (more preferably 0.25 to 0.35, and further preferably 0.26 to 0.30). By setting this mass ratio within the above range, the friction reduction performance can be maintained and the LSPI suppression ability can be improved.

Furthermore, in the lubricating oil composition for internal combustion engines of the present invention, the ratio of the content of boron based on the total amount of the lubricating oil composition to the total amount (total amount) of calcium based on the total amount of the lubricating oil composition and magnesium based on the total amount of the lubricating oil composition [mass ratio: [boron]/([calcium]+[magnesium])] is preferably 0.13 to 0.29 (more preferably 0.20 to 0.29, and further preferably 0.25 to 0.28). By setting such a mass ratio within the above range, the friction reduction performance can be maintained and the LSPI suppression ability can be improved.

The lubricating oil composition for an internal combustion engine of the present invention has a kinematic viscosity at 100° C. of 4.0 to 9.3 mm ² /s (more preferably 6.5 to 8.0 mm ² /s). Furthermore, the lubricating oil composition of the present invention has a kinematic viscosity of 23.0 to 40.0 mm ² /s (more preferably 26.0 to 30.0 mm ² /s) at 40°C. When the kinematic viscosity is below the above upper limit, the fuel consumption performance can be further improved compared to when the kinematic viscosity exceeds the above upper limit. On the other hand, when the kinematic viscosity is equal to or higher than the above-mentioned lower limit, the wear resistance obtained by maintaining the oil film can be improved compared to the case where the kinematic viscosity is less than the above-mentioned lower limit.

The lubricating oil composition for internal combustion engines of the present invention preferably has a viscosity index of 180 or more (more preferably 200 or more, further preferably 220 or more, and particularly preferably 225 or more). When the viscosity index is above the lower limit, the viscosity-temperature characteristics and anti-wear properties of the lubricating oil composition can be improved compared to the case where the viscosity index is below the lower limit, and the fuel consumption performance can be further improved. In addition, when the viscosity index is above the lower limit, the evaporation loss of the lubricating oil can be reduced, thereby reducing the consumption of the lubricating oil.

In addition, the HTHS (High Temperature High Shear) viscosity of the lubricating oil composition for internal combustion engines of the present invention at 150°C is preferably 1.7 mPa·s or more and 2.9 mPa·s or less (more preferably 2.3 mPa·s More than 2.8 mPa・s and less, more preferably 2.6 mPa・s and less than 2.8 mPa・s, particularly preferably 2.6 mPa・s). When the HTHS viscosity at 150°C is above the above lower limit, the wear resistance under shear conditions can be improved compared to the case where the HTHS viscosity is below the above lower limit. On the other hand, when the above upper limit is When the value is below the upper limit, the fuel consumption performance can be further improved by reducing the viscous drag compared to when the upper limit is exceeded. Furthermore, in this specification, the so-called "HTHS viscosity at 150°C" means the high temperature high shear viscosity at 150°C measured in accordance with ASTM D-4683.

The method for producing the lubricating oil composition for internal combustion engines of the present invention is not particularly limited as long as each component contained is appropriately selected in such a manner that the lubricating oil composition of the present invention can be obtained (a manner that satisfies the above conditions) , and prepare by mixing. Example

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Regarding the components used in each embodiment, etc.) First, the lubricating oil base oil and additives used in each embodiment, etc. are shown below.

<(A) Component: Lubricating base oil> (A-1) API Group II base oil (hydrocracked mineral oil-based base oil, Yubase (registered trademark) 3 manufactured by SK Lubricants), dynamic viscosity (100°C) : 3.05 mm ² /s, dynamic viscosity (40°C): 12.3 mm ² /s, viscosity index: 105, NOACK evaporation amount (250°C, 1 h): 40 mass%, %C _P : 72.6, %C _N : 27.4, %C _A : 0, saturated content: 99.6 mass%, aromatic content: 0.3 mass% (A-2) API Group III base oil (hydrocracked mineral oil base oil, Yubase manufactured by SK Lubricants (registered Trademark) 4+), dynamic viscosity (100°C): 4.2 mm ² /s, dynamic viscosity (40°C): 17.9 mm ² /s, viscosity index: 134, NOACK evaporation amount (250°C, 1 h): 13.5 mass %, %C _P : 87.2, %C _N : 12.8, %C _A : 0, saturated component: 99.8 mass%, aromatic component: 0.1 mass% (A-3) API Group III base oil (hydrocracked mineral oil Base oil, Yubase (registered trademark) 6+ manufactured by SK Lubricants, dynamic viscosity (100°C): 6.4 mm ² /s, dynamic viscosity (40°C): 33.8 mm ² /s, viscosity index: 145, NOACK Evaporation amount (250°C, 1 h): 8 mass%, % _CP : 85%, C _N : 15%, C _A : 0%, saturated component: 99.5 mass%, aromatic component: 0.2 mass%

<(B) Ingredients: Metal-based cleaners> <(B1) Ingredients: Calcium-based cleaners> (B1-i) Calcium borate peralkalized calcium salicylate, calcium content: 6.8 mass%, boron content: 2.7 mass%, alkalinity (perchloric acid method): 190 mgKOH/g (B1-ii) Calcium carbonate peralkalized calcium salicylate, calcium content: 8.0 mass%, alkalinity (perchloric acid method): 210 mgKOH/g <(B2) Ingredients: Magnesium-based cleaners> (B2-i) Magnesium carbonate peralkalized magnesium salicylate, magnesium content: 7.5 mass%, alkalinity (perchloric acid method): 350 mgKOH/g (B2-ii) The content of magnesium carbonate peralkalized magnesium sulfonate and magnesium: 9.1 mass %, alkalinity (perchloric acid method): 400 mgKOH/g.

＜(C) Ingredient: Viscosity index enhancer (poly(meth)acrylate viscosity index enhancer)＞ (C-1) Comb-shaped polymethacrylate polymer (manufactured by Sanyo Chemical Industry Co., Ltd., trade name: Aqualube V-7030, Mw: 520,000, Mn: 220,000, Mw/Mn: 2.4) (C-2) Linear polymethacrylate polymer (manufactured by Sanyo Chemical Industry Co., Ltd., trade name: Aqualube V-5090, Mw: 480,000, Mn: 170,000, Mw/Mn: 2.8).

＜(D)Component: Ashless dispersant＞ (D-1) Non-borated succinimide (nitrogen content: 1.6 mass%, Mw: 6000) (D-2) Boronized succinimide (nitrogen content: 1.2 mass%, boron content: 0.5 mass%, Mw: 7000).

<(E) Ingredient: Antioxidant> (E-1) Amine antioxidant (manufactured by BASF, trade name: IRGANOX (registered trademark) L67, bis(nonylphenyl)amine, nitrogen content: 3.6% by mass) (E-2) Molybdenum antioxidant (molybdenum acid dialkylamine salt, molybdenum content: 10% by mass, nitrogen content: 3.6% by mass).

<(F) Component: Friction adjuster (molybdenum-based friction adjuster)> (F-1) Molybdenum dithiocarbamate (MoDTC, manufactured by ADEKA Co., Ltd., trade name: ADEKA SAKURA-LUBE525, molybdenum content (theoretical value): 10.0% by mass).

<(G) Anti-wear agent> (G-1) Zinc dialkyl dithiophosphate (ZnDTP, secondary alkyl type, represented by the above formula (4) and R ¹⁴ to R ¹⁷ in the formula (4) are respectively A compound that is either a secondary alkyl group with 4 or 6 carbon atoms, zinc content: 8.0 mass%, phosphorus content: 7.0 mass%, sulfur content: 14 mass%) (G-2) Dioxane Zinc dithiophosphate (ZnDTP, primary alkyl type, a compound represented by the above formula (4) and R ¹⁴ to R ¹⁷ in the formula (4) are all primary alkyl groups with 8 carbon atoms, zinc content: 8.0 Mass %, phosphorus content: 7.0 mass %, sulfur content: 15 mass %) (G-3) Zinc dialkyl phosphate (ZnP, carbon number 8 primary alkyl type, zinc content: 5.3 mass %, phosphorus Content: 5.2 mass%).

<(H) Component: Pour point depressant> (H-1) Polymethacrylate (manufactured by Evonik INDUSTRIES, trade name: Viscoplex 1-300, Mw: 60,000, Mn: 32,000, Mw/Mn: 1.9).

＜(I) Ingredients: Other additives＞ (I-1) Defoaming agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KF-96H").

(Examples 1 to 5 and Comparative Examples 1 to 10) The lubricating oil compositions of Examples 1 to 5 and Comparative Examples 1 to 10 were prepared using the above-mentioned components in the manner of the compositions shown in Tables 1 to 3. In addition, with respect to the "Composition" item in Tables 1 to 3, "-" indicates that the component is not used. In addition, in the "Composition" item in Tables 1 to 3, the unit "mass%" of the content of component (A) indicates the content (mass%) of each base oil component relative to the total amount of the lubricating oil base oil, the unit "inmass%" of the content of components (B) to (H) indicates the content (mass%) of each additive relative to the total amount of the lubricating oil composition, and "parts by mass" indicates the ratio (parts by mass) of component (I-1) when the total mass of the components in the lubricating oil composition other than component (I-1) is set to 100 parts by mass. In Tables 1 to 3, the unit "massppm" of [B _(B1) ] represents the mass parts per million (mass ppm) of boron derived from the component (B1) based on the total amount of the lubricating oil composition, the unit "massppm" of [Ca _(B1) ] represents the mass parts per million (mass ppm) of calcium derived from the component (B1) based on the total amount of the lubricating oil composition, and the unit "massppm" of [Mg _(B2) ] represents the mass parts per million (mass ppm) of magnesium derived from the component (B2) based on the total amount of the lubricating oil composition. Furthermore, in the "Content of each element in the composition" item in Tables 1 to 3, the unit "mass ppm" related to the content of B, Ca, Mg, Mo, P, S, and Zn represents the mass parts per million (mass ppm) of each element (B, Ca, Mg, Mo, P, S, and Zn) based on the total amount of the lubricating oil composition. Furthermore, the values of the contents of B, Ca, Mg, Mo, P, S, and Zn in the "Content of each element in the composition" item in Tables 1 to 3 are the values measured in accordance with JPI-5S-62.

[Evaluation of the properties of the lubricating oil compositions obtained in each embodiment, etc.] ＜LSPI performance evaluation test (LSPI test)＞ Each lubricating oil composition was subjected to an evaluation test of LSPI inhibition ability according to ASTM D8291 [Test method: Sequence 9 test (Seq.IX ASTM D8291), engine used: Ford engine manufactured in 2012 (2000 CC, 4 cylinders, GDTI engine)]. The average value of the number of LSPI occurrences of each lubricating oil composition obtained by this measurement is shown as the LSPI test results in Tables 1 to 3. In addition, the LSPI test results (average value of LSPI occurrence times) are evaluated to see whether they meet the condition of "5" or below the benchmark value of the engine oil standard "API SP/ILSAC GF-6". In Tables 1 to 3, if it is below the benchmark value (meets the benchmark), it is indicated as "S", and if it exceeds the benchmark value (does not meet the benchmark), it is indicated as "F". Furthermore, when the LSPI test results meet the condition of 5 or below the benchmark value of "API SP/ILSAC GF-6", the lubricating oil composition can be evaluated as having excellent LSPI inhibition ability.

<SRV test (fuel saving performance evaluation test)> Using each lubricating oil composition, the SRV test was carried out using a cylinder-on-disk reciprocating friction tester (SRV manufactured by Optimol) under the test conditions of load 100 N, disk temperature 100°C, vibration number 50 Hz, amplitude 1 mm, and test time 15 minutes to measure the friction coefficient between metals. The obtained results are shown in Tables 1 to 3. In addition, it can be seen that when the friction coefficient value is 0.060 or less, the friction characteristics are excellent, so the lubricating oil composition can be evaluated as having excellent fuel saving performance.

[Table 1] Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Composition (A) Lubricating oil base oil (A-1) mass% 7 7 7 7 7 (A-2) mass% 93 93 93 93 93 (A-3) mass% - - - - - (B) Metal Cleaners (B1) (B1-i) inmass% 2.1 1.7 1.9 2.2 2.1 (B1-ii) inmass% 0.55 0.71 0.93 0.61 0.55 (B2) (B2- i) inmass% - - - - - (B2- ii) inmass% 0.16 0.11 0.11 0.11 0.16 (C) Viscosity index enhancer (C-1) inmass% 10.5 7 7 7 10.5 (C-2) inmass% - - - - - (D) Ashless dispersant (D-1) inmass% 2.4 2.4 2.4 2.4 2.4 (D-2) inmass% - - - - - (E) Antioxidants (E-1) inmass% 1.7 1.7 1.7 1.7 1.7 (E-2) inmass% 0.2 0.2 0.2 0.2 0.2 (F) Friction adjuster (F-1) inmass% 0.8 0.8 0.8 0.8 0.8 (G) Anti-wear agent (G-1) inmass% 0.7 0.7 0.7 0.7 0.55 (G-2) inmass% 0.4 0.4 0.4 0.4 0.35 (G-3) inmass% - - - - - (H) Flow point lowering agent (H-1) inmass% 0.3 0.3 0.3 0.3 0.3 (I) Other ingredients (defoaming agent) (I-1) Quality 0.002 0.002 0.002 0.002 0.002 Content of B from component (B1) [B _(B1) ] massppm 550 450 500 600 550 Content of Ca from component (B1) [Ca _(B1) ] massppm 1850 1700 2000 2000 1850 Content of Mg from component (B2) [Mg _(B2) ] massppm 150 100 100 100 150 [B _(B1) ]/[Ca _(B1) ] Mass ratio 0.30 0.26 0.25 0.30 0.30 [B _(B1) ]/([Ca _(B1) ]＋[Mg _(B2) ]) Mass ratio 0.28 0.25 0.24 0.29 0.28 The content of each element in the composition (based on the total amount of the composition) B massppm 550 450 500 600 550 Ca massppm 1850 1700 2000 2000 1850 Mg massppm 150 100 100 100 150 Mo massppm 1000 1000 1000 1000 1000 P massppm 770 770 770 770 600 S massppm 2500 2500 2500 2500 2200 Zn massppm 880 880 880 880 720 Base oil properties Kinematic viscosity at 100℃ mm ² /s 4.1 4.1 4.1 4.1 4.1 Physical properties of the composition Kinematic viscosity at 40℃ mm ² /s 27.6 27.3 26.4 26.4 27.6 Kinematic viscosity at 100℃ mm ² /s 7.6 6.8 6.6 6.6 7.6 HTHS viscosity at 150℃ mPa・s 2.6 2.3 2.3 2.3 2.6 Viscosity index 267 225 223 223 267 Evaluation results of the properties of the composition LSPI test results (Seq.IX, ASTM D8291) 1.9 2.3 1.5 2.5 4.1 Evaluation relative to API SP/ILSAC GF-6 benchmark S S S S S SRV test results (friction coefficient) 0.051 0.058 0.054 0.057 0.054

[Table 2] Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 composition (A) Lubricant base oil (A-1) mass% 7 - - - - (A-2) mass% 93 70 70 70 70 (A-3) mass% - 30 30 30 30 (B) Metal based cleaner (B1) (B1-i) inmass% 2.1 2.1 0.8 - 2.9 (B1-ii) inmass% 1.5 - 1.2 1.3 - (B2) (B2-i) inmass% - 0.65 0.65 1.3 - (B2-ii) inmass% 0.16 - - - - (C) Viscosity index improving agent (C-1) inmass% 10.5 - - - - (C-2) inmass% - 13 13 13 13 (D)Ashless dispersant (D-1) inmass% 2.4 0.8 0.8 0.8 0.8 (D-2) inmass% - 4 4 4 4 (E)Antioxidants (E-1) inmass% 1.7 1.7 1.7 1.7 1.7 (E-2) inmass% 0.2 0.15 0.15 0.15 0.15 (F) Friction adjuster (F-1) inmass% 0.8 - - - - (G) Anti-wear agent (G-1) inmass% 0.7 - - - - (G-2) inmass% 0.4 - - - - (G-3) inmass% - 1.3 1.3 1.3 1.3 (H) Pour point depressant (H-1) inmass% 0.3 0.3 0.3 0.3 0.3 (I) Other ingredients (defoamer) (I-1) parts by mass 0.002 0.002 0.002 0.002 0.002 Content of B derived from component (B1) [B _(B1) ] massppm 550 550 200 0 800 Content of Ca derived from component (B1) [Ca _(B1) ] massppm 2600 1400 1500 1000 2000 Content of Mg derived from component (B2) [Mg _(B2) ] massppm 150 500 500 950 10 [B _(B1) ]/[Ca _(B1) ] mass ratio 0.21 0.39 0.13 0.00 0.40 [B _(B1) ]/([Ca _(B1) ] + [Mg _(B2) ]) mass ratio 0.20 0.29 0.10 0.00 0.40 Content of each element in the composition (based on the total amount of the composition) B massppm 550 750 400 200 1000 Ca massppm 2600 1400 1500 1000 2000 Mg massppm 150 500 500 950 10 Mo massppm 1000 150 150 150 150 P massppm 770 700 700 700 700 S massppm 2500 800 800 800 800 Zn massppm 880 690 690 690 690 Physical properties of base oil Kinematic viscosity at 100℃ mm ² /s 4.1 4.7 4.7 4.7 4.7 physical properties of composition Kinematic viscosity at 40℃ mm ² /s 28.3 39.2 39.2 39.2 39.4 Kinematic viscosity at 100℃ mm ² /s 7.7 9 9 9 9 HTHS viscosity at 150℃ mPa·s 2.6 2.9 2.9 2.9 2.9 viscosity index 263 221 221 221 220 Evaluation results of the properties of the composition LSPI test results (Seq.IX, ASTM D8291) 8.1 5.1 7.7 5.1 5.9 Evaluation relative to benchmark values of API SP/ILSAC GF-6 F F F F F SRV test results (friction coefficient) 0.065 0.137 0.133 0.138 0.130

[table 3] Comparative example 6 Comparative example 7 Comparative example 8 Comparative example 9 Comparative example 10 composition (A) Lubricant base oil (A-1) mass% - - - - - (A-2) mass% 70 70 70 70 70 (A-3) mass% 30 30 30 30 30 (B) Metal based cleaner (B1) (B1-i) inmass% - - 1.4 - 2.2 (B1-ii) inmass% 2.5 3.2 - 1.8 - (B2) (B2-i) inmass% 0.4 - 1.2 0.4 0.65 (B2-ii) inmass% - - - - - (C) Viscosity index improving agent (C-1) inmass% - - - - 11 (C-2) inmass% 13 13 13 13 - (D)Ashless dispersant (D-1) inmass% 0.8 0.8 0.8 0.8 0.8 (D-2) inmass% 4 4 4 4 4 (E)Antioxidants (E-1) inmass% 1.7 1.7 1.7 1.7 1.7 (E-2) inmass% 0.15 0.15 0.15 0.15 0.15 (F) Friction adjuster (F-1) inmass% - - - - - (G) Anti-wear agent (G-1) inmass% - - - - - (G-2) inmass% - - - - - (G-3) inmass% 1.3 1.3 1.3 1.3 1.3 (H) Pour point depressant (H-1) inmass% 0.3 0.3 0.3 0.3 0.3 (I) Other ingredients (defoamer) (I-1) parts by mass 0.002 0.002 0.002 0.002 0.002 Content of B derived from component (B1) [B _(B1) ] massppm 0 0 400 0 600 Content of Ca derived from component (B1) [Ca _(B1) ] massppm 2000 2500 950 1500 1500 Content of Mg derived from component (B2) [Mg _(B2) ] massppm 300 10 900 300 500 [B _(B1) ]/[Ca _(B1) ] mass ratio 0.00 0.00 0.42 0.00 0.40 [B _(B1) ]/([Ca _(B1) ] + [Mg _(B2) ]) mass ratio 0.00 0.00 0.22 0.00 0.30 Content of each element in the composition (based on the total amount of the composition) B massppm 200 200 600 200 800 Ca massppm 2000 2500 950 1500 1500 Mg massppm 300 10 900 300 500 Mo massppm 150 150 150 150 150 P massppm 700 700 700 700 700 S massppm 800 800 800 800 800 Zn massppm 690 690 690 690 690 Physical properties of base oil Kinematic viscosity at 100℃ mm ² /s 4.7 4.7 4.7 4.7 4.7 physical properties of composition Kinematic viscosity at 40℃ mm ² /s 39.3 39.4 39.3 39.4 34.4 Kinematic viscosity at 100℃ mm ² /s 8.9 8.9 9 9 8.5 HTHS viscosity at 150℃ mPa·s 2.9 2.9 2.9 2.9 2.9 viscosity index 217 216 220 220 239 Evaluation results of the properties of the composition LSPI test results (Seq.IX, ASTM D8291) 23.8 21.5 1.8 21.3 5.0 Evaluation relative to benchmark values of API SP/ILSAC GF-6 F F S F S SRV test results (friction coefficient) 0.116 0.112 0.139 0.118 0.140

According to the results shown in Table 1, the lubricating oil compositions obtained in Examples 1 to 5 have excellent LSPI suppression capability and fuel consumption performance (friction characteristics). The lubricating oil compositions obtained in Examples 1 to 5 include (A) a lubricating oil base oil and (B) a metal-based detergent, wherein the component (B) includes a calcium-based detergent (component (B1)) and a magnesium-based detergent (component (B2)). The calcium in the component (B1) is The content of is in the range of 1650 mass ppm to 2500 mass ppm based on the total mass of the composition, which is due to the fact that the content of magnesium in the component (B2) is in the range of 20 mass ppm to 400 mass ppm based on the total mass of the composition, the component (B1) includes the component (B1-i) (a component containing boron and calcium), the total amount of B in the composition is less than 1000 mass ppm, B _(B1) /Ca _(B1) is in the range of 0.15 to 0.35, and B _(B1) /[Ca _(B1) +Mg _(B2) ] is in the range of 0.13 to 0.29. Furthermore, the lubricating oil compositions obtained in Comparative Examples 2 and 9, in which B _(B1) /Ca _(B1) is not within the range of 0.15 or more and 0.35 or less, have a higher friction coefficient than the lubricating oil compositions obtained in Examples 1 to 5 even if B _(B1) /[Ca _(B1) +Mg _(B2) ] is 0.29. [Industrial Applicability]

As described above, according to the present invention, a lubricating oil composition for internal combustion engines having excellent LSPI suppression capability and fuel saving performance can be provided. Therefore, the lubricating oil composition for internal combustion engines of the present invention is particularly effective as a lubricating oil composition for engines such as gasoline engines and diesel engines.

Claims (4)

A lubricating oil composition for internal combustion engines, which contains (A) lubricating oil base oil and (B) metallic detergent. The above (B) component contains (B1) calcium content based on the total mass of the composition. Calcium-based cleaners in the range of 1,650 ppm by mass or more and 2,500 ppm by mass or less, and (B2) Magnesium-based cleaners with magnesium content in the range of 20 ppm by mass or more and 150 ppm by mass or less based on the total mass of the composition. Agent, the above (B1) component contains (B1-1) a calcium-based detergent containing boron and calcium, the boron content based on the total mass of the composition is 1000 mass ppm or less, and the total mass of the composition is used The boron content in the component (B1) based on the total mass of the composition is expressed as B _(B1) . The calcium content in the component (B1) based on the total mass of the composition is expressed as Ca _(B1) . When the magnesium content in component (B2) based on the total mass is expressed as Mg _(B2) , the ratio of B _(B1) to Ca _(B1) (B _(B1) /Ca _(B1) ) is 0.15 or more 0.30 or less, and the ratio of B _(B1) to the total amount of Ca _(B1) and Mg _(B2) (Ca _(B1) +Mg _(B2) ) (B _(B1) /[Ca _(B1) +Mg _{(B2) )} ]) is above 0.13 and below 0.29. The lubricating oil composition for internal combustion engines as claimed in claim 1, wherein the component (B1) contains calcium borate salicylate as the component (B1-1). The lubricating oil composition for internal combustion engines of claim 1 or 2 further contains (C) a poly(meth)acrylate viscosity index improver. The lubricating oil composition for an internal combustion engine according to claim 3, wherein the component (C) contains a comb-shaped poly(meth)acrylate polymer.