Lubricant composition

Abstract

To provide a lubricant composition having high metal corrosion resistance and capable of being suitably used for lubrication of an internal combustion engine using a fuel containing ammonia.SOLUTION: A lubricant composition used for lubrication of a marine engine using a fuel containing ammonia comprises a base oil (A), an amide-based compound (B), a metal deactivator (C), an organic zinc dithiophosphate (D), and a calcium-based detergent (E), wherein a content of the component (C) is less than 0.30 mass% based on the total amount of the lubricant composition, a content of the component (E) in terms of calcium atoms is 5,000 mass ppm or more based on the total amount of the lubricant composition, a base number of the lubricant composition is 10.0 or more, and a sulfated ash content of the lubricant composition is more than 1.10 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to lubricating oil compositions and methods of using lubricating oil compositions. [Background technology]

[0002] Various requirements are placed on internal combustion engines installed in automobiles, ships, trains, etc., and lubricating oil compositions for use in internal combustion engines are being developed to meet these requirements. For example, Patent Document 1 discloses an invention relating to a lubricating oil composition for diesel engines, which contains 14% by mass or more of a fraction having a boiling point of 500 to 550°C and 5% by mass or more of a fraction having a boiling point exceeding 550°C.

[0003] While hydrocarbon fuels such as diesel oil and natural gas, petroleum gas, and other fuels have been used to fuel internal combustion engines, the use of ammonia as a fuel is also being considered. Ammonia is a compound obtained from petroleum, biomass, and renewable energy sources (wind, solar, hydroelectric, and geothermal). Ammonia produced using renewable energy sources has a virtually zero carbon footprint when burned, and virtually zero emissions of CO2, SOx, particulate matter, and unburned hydrocarbons. For this reason, development of an internal combustion engine that uses ammonia as fuel, as disclosed in Patent Document 2, is also underway. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-196595 [Patent Document 2] Japanese Patent Publication No. 2022-075566 Summary of the Invention [Problem to be solved by the invention]

[0005] Meanwhile, lubricating oil compositions for use in lubricating internal combustion engines that use ammonia-containing fuel have also been developed. The ammonia used as fuel can corrode metals such as copper that make up the components of the internal combustion engine. Therefore, there is a demand for lubricating oil compositions that have high resistance to metal corrosion and that can be suitably used to lubricate internal combustion engines that use fuels containing ammonia. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by a lubricating oil composition that contains a base oil, an amide-based friction modifier, a predetermined amount of a metal deactivator, an organic zinc dithiophosphate, and a predetermined amount of a calcium-based detergent, and that has a base number and sulfated ash content within predetermined ranges. Specifically, the present invention discloses the following aspects. [1] A lubricating oil composition comprising a base oil (A), an amide-based friction modifier (B), a metal deactivator (C), an organic zinc dithiophosphate (D), and a calcium-based detergent (E), The content of component (C) is less than 0.30 mass% based on the total amount of the lubricating oil composition, The content of component (E) in terms of calcium atoms is 5000 ppm by mass or more based on the total amount of the lubricating oil composition, The base number of the lubricating oil composition is 10.0 mgKOH / g or more, The sulfated ash content of the lubricating oil composition is greater than 1.10% by mass. A lubricating oil composition for use in lubricating marine engines that use fuels containing ammonia. [2] The kinematic viscosity of the lubricating oil composition at 40 ° C. is 100 mm 2 / s or more. [3] The lubricating oil composition according to the above [1] or [2], wherein component (B) comprises a fatty acid amide (D1). [4] The lubricating oil composition according to any one of the above [1] to [3], wherein the content of component (B) is 0.01 to 5.00 mass % based on the total amount of the lubricating oil composition. [5] The lubricating oil composition according to any one of the above [1] to [4], wherein component (C) comprises one or more compounds selected from the group consisting of thiadiazole-based compounds, benzotriazole-based compounds, and tolyltriazole-based compounds. [6] The lubricating oil composition according to any one of the above [1] to [5], wherein the content of component (D) in terms of zinc atoms is 100 to 7000 ppm by mass based on the total amount of the lubricating oil composition. [7] The lubricating oil composition according to any one of the above [1] to [6], further comprising an antioxidant (F). [8] The lubricating oil composition according to the above [7], wherein component (F) comprises at least one selected from the group consisting of phenolic antioxidants and amine antioxidants. [9] The lubricating oil composition according to any one of the above [1] to [8], further comprising an imide-based compound (G).

[10] The lubricating oil composition according to any one of the above [1] to [9], wherein the base number of the lubricating oil composition is 12.0 to 30.0 mgKOH / g.

[11] A method for lubricating a marine engine, comprising applying the lubricating oil composition according to any one of the above [1] to

[10] to lubricate a marine engine that uses a fuel containing ammonia. [Effects of the Invention]

[0007] The lubricating oil composition of a preferred embodiment of the present invention has excellent metal corrosion resistance and can therefore be suitably used for lubricating internal combustion engines that use fuels containing ammonia. DETAILED DESCRIPTION OF THE INVENTION

[0008] The upper and lower limits of the numerical ranges described herein can be combined in any combination. For example, if a numerical range is described as "preferably 30 to 100, more preferably 40 to 80," the range "30 to 80" and the range "40 to 100" are also included in the numerical ranges described herein. Furthermore, for example, when a numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less," the range of "30 to 80" and the range of "40 to 100" are also included in the numerical range described in this specification. In other words, in specifying the upper and lower limits described in this specification, the numerical range from the lower limit to the upper limit can be specified by appropriately selecting from the respective options and combining them as desired. Furthermore, as a numerical range described in this specification, for example, "60 to 100" means a range of "60 or more and 100 or less." In addition, the various features described as preferred embodiments in this specification can be combined in multiple ways.

[0009] In this specification, the kinematic viscosity and viscosity index refer to values ​​measured and calculated in accordance with JIS K2283:2000. In this specification, the contents of alkali metal atoms, alkaline earth metal atoms, zinc atoms (Zn), and molybdenum atoms (Mo) refer to values ​​measured in accordance with JPI-5S-38-92.

[0010] [Constitution of lubricating oil composition] A lubricating oil composition according to one embodiment of the present invention contains a base oil (A), an amide-based friction modifier (B), a metal deactivator (C), an organic zinc dithiophosphate (D), and a calcium-based detergent (E). In recent years, ammonia fuels have been attracting attention for their environmental advantages, such as virtually zero carbon footprint when burned and virtually zero emissions of CO2, SOx, particulate matter, and unburned hydrocarbons. The lubricating oil composition of one embodiment of the present invention is formulated for use in lubricating internal combustion engines (particularly marine engines) that use fuels containing such ammonia.

[0011] When ammonia is used as a fuel, there is a problem that metals such as copper constituting the components of an internal combustion engine are easily corroded. Therefore, a lubricating oil composition used in an internal combustion engine is required to have high metal corrosion resistance against the metals (particularly copper) constituting the components of the internal combustion engine. Furthermore, ammonia has a high minimum ignition energy and is difficult to burn as a fuel, so it is used in combination with hydrocarbon fuel. Marine hydrocarbon fuels generally also contain a high amount of sulfur. For example, while the maximum sulfur content of fuel-derived sulfur in ordinary gasoline and diesel is approximately 0.001% by mass, marine hydrocarbon fuels have a maximum of approximately 0.5% by mass. Combustion of fuels with a high sulfur content produces sulfuric acid, which must be neutralized. Furthermore, oxides are produced after ammonia combustion, so these nitrogen oxides must also be neutralized. In order to neutralize sulfuric acid and nitrogen oxides in this way, the lubricating oil composition of one embodiment of the present invention has a high calcium-based detergent content and adjusts the base number and sulfated ash content.

[0012] In one embodiment of the lubricating oil composition of the present invention, from the viewpoint of providing a lubricating oil composition that can neutralize sulfuric acid produced when marine hydrocarbon fuel is burned and nitrogen oxides produced when ammonia is burned, the base number is 10.0 mgKOH / g or more, and is preferably 11.0 mgKOH / g or more, 12.0 mgKOH / g or more, 13.0 mgKOH / g or more, 14.0 mgKOH / g or more, 15.0 mgKOH / g or more, 16.0 mgKOH / g or more, 17.0 mgKOH / g or more, 18.0 mgKOH / g or more, 19.0 mgKOH / g or more, 20.0 mgKOH / g or more, 21.0 mgKOH / g, or 22.0 mgKOH / g or more.

[0013] When the lubricating oil composition of one embodiment of the present invention is used to lubricate an inland marine engine, the base number of the lubricating oil composition is preferably 30.0 mgKOH / g or less, 28.0 mgKOH / g or less, 26.0 mgKOH / g or less, 24.0 mgKOH / g or less, 23.0 mgKOH / g or less, 22.0 mgKOH / g or less, 21.0 mgKOH / g or less, or 20.0 mgKOH / g or less.

[0014] Furthermore, when the lubricating oil composition of one embodiment of the present invention is used to lubricate marine engines, the base number of the lubricating oil composition may be 30.0 mgKOH / g or more, 35.0 mgKOH / g or more, 40.0 mgKOH / g or more, 45.0 mgKOH / g or more, or 50.0 mgKOH / g or more, and may be 200 mgKOH / g or less, 150 mgKOH / g or less, 100 mgKOH / g or less, 80.0 mgKOH / g or less, 70.0 mgKOH / g or less, or 60.0 mgKOH / g or less.

[0015] In this specification, the base number refers to a value measured in accordance with "9. Potentiometric titration method (perchloric acid method)" of JIS K2501 "Petroleum products and lubricants - Testing method for neutralization number."

[0016] In one embodiment of the lubricating oil composition of the present invention, from the viewpoint of providing a lubricating oil composition that can neutralize sulfuric acid produced when marine hydrocarbon fuel is burned and nitrogen oxides produced when ammonia is burned, the sulfated ash content is more than 1.1 mass%, but may also be 1.2 mass% or more, 1.3 mass% or more, 1.4 mass% or more, 1.5 mass% or more, 1.6 mass% or more, 1.7 mass% or more, 1.8 mass% or more, 1.9 mass% or more, 2.0 mass% or more, 2.1 mass% or more, 2.2 mass% or more, 2.3 mass% or more, or 2.4 mass% or more, and may also be 10.0 mass% or less, 9.0 mass% or less, 8.0 mass% or less, 7.0 mass% or less, 6.0 mass% or less, 5.0 mass% or less, 4.5 mass% or less, 4.0 mass% or less, 3.5 mass% or less, or 3.0 mass% or less. In this specification, the sulfated ash content refers to a value measured in accordance with JIS K2272:1998.

[0017] The lubricating oil composition of one embodiment of the present invention may further contain an antioxidant (F). The lubricating oil composition of one embodiment of the present invention may further contain an imide-based compound (G). The lubricating oil composition of one embodiment of the present invention may further contain other lubricating oil additives in addition to components (A) to (G) to the extent that the effects of the present invention are not impaired.

[0018] In the lubricating oil composition of one embodiment of the present invention, the total content of components (A) to (E) is preferably 60 mass% or more, 65 mass% or more, 70 mass% or more, 75 mass% or more, 80 mass% or more, 85 mass% or more, or 90 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, and may be 100 mass% or less, 99.9 mass% or less, 99.0 mass% or less, 98.0 mass% or less, 97.0 mass% or less, 96.0 mass% or less, or 95.0 mass% or less.

[0019] In the lubricating oil composition of one embodiment of the present invention, the total content of components (A) to (G) is preferably 60 mass% or more, 65 mass% or more, 70 mass% or more, 75 mass% or more, 80 mass% or more, 85 mass% or more, 90 mass% or more, 93 mass% or more, or 95 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, and may be 100 mass% or less, 99.9 mass% or less, 99.0 mass% or less, 98.0 mass% or less, or 97.0 mass% or less.

[0020] Hereinafter, each component contained in the lubricating oil composition of one embodiment of the present invention will be described in detail.

[0021] <Component (A): Base oil> In the lubricating oil composition of one embodiment of the present invention, the base oil used as component (A) may be one or more selected from mineral oils and synthetic oils. Examples of mineral oils include atmospheric residues obtained by atmospheric distillation of crude oils such as paraffin-based crude oil, intermediate-based crude oil, and naphthene-based crude oil; distillates obtained by vacuum distillation of these atmospheric residues; and refined oils obtained by subjecting the distillates to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0022] Examples of synthetic oils include poly-α-olefins such as α-olefin homopolymers or α-olefin copolymers (e.g., α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffins; polyalkylene glycols; ester oils such as polyol esters, dibasic acid esters, and phosphate esters; ether oils such as polyphenyl ethers; alkylbenzenes; alkylnaphthalenes; synthetic oils (GTL) obtained by isomerizing wax produced from natural gas by the Fischer-Tropsch process or the like (GTL wax (Gas to Liquids Wax)); CTL base oils obtained by direct liquefaction methods (such as the Bergius process) in which coal is crushed, mixed with a solvent, and then directly reacted with hydrogen under high temperature and pressure; and CTL base oils obtained by indirect liquefaction methods (such as the Fischer-Tropsch process) in which coal is gasified (coal gasification) and the resulting gas is then synthetically reacted with separated and purified raw materials to liquefy the resulting gas.

[0023] The kinematic viscosity at 40°C of the component (A) used in one embodiment of the present invention is 20 mm 2 / s or more, 50mm 2 / s or more, 70mm 2 / s or more, 90mm 2 / s or more, 100mm 2 / s or more, 110mm 2 / s or more, 120mm 2 / s or more, 130mm 2 / s or more, or 140 mm 2 / s or more is preferable, and 2 / s or less, 450mm 2 / s or less, 400mm 2 / s or less, 350mm 2 / s or less, 300mm 2 / s or less, 250mm 2 / s or less, 220mm 2 / s or less, 200mm 2 / s or less, 190mm 2 / s or less, 180mm 2 / s or less, or 170 mm 2 It is preferable to set it to / s or less.

[0024] The viscosity index of component (A) used in one embodiment of the present invention is preferably 70 or more, more preferably 80 or more, even more preferably 90 or more, still more preferably 95 or more, and particularly preferably 100 or more, and may also be 200 or less, 180 or less, 160 or less, 140 or less, or 120 or less. In one embodiment of the present invention, when a mixed oil of two or more base oils is used as component (A), the mixed oil preferably has a kinematic viscosity and viscosity index within the above ranges. The kinematic viscosity or viscosity index of the mixed oil can be determined by calculating a weighted average of the kinematic viscosity or viscosity index of each of the base oils constituting the mixed oil and their content ratios.

[0025] In the lubricating oil composition of one embodiment of the present invention, the content of component (A) is preferably 40 mass% or more, 45 mass% or more, 50 mass% or more, 55 mass% or more, 60 mass% or more, 65 mass% or more, 70 mass% or more, 75 mass% or more, or 80 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, and may be 99.5 mass% or less, 99.0 mass% or less, 97.0 mass% or less, 95.0 mass% or less, 92.0 mass% or less, or 90.0 mass% or less.

[0026] <Component (B): Amide-based compound> The lubricating oil composition of one embodiment of the present invention contains an amide compound as component (B). By containing component (B), metal corrosion resistance is improved, and the lubricating oil composition can be made suitable for use in lubricating internal combustion engines that use fuels containing ammonia. In one embodiment of the present invention, the component (B) may be used alone or in combination of two or more types.

[0027] In this specification, "amide-based compound" means a compound having an amide structure (excluding structures corresponding to imide structures) represented by the following formula (b-0), and also includes a chain compound having the amide structure and a cyclic compound having the amide structure. Furthermore, "amide-based compound" may be any compound having the amide structure, and includes, for example, fatty acid amides, aromatic amides, alicyclic amides, etc. [ka] (In the above formula, * indicates the bond position.)

[0028] Examples of component (B) used in one embodiment of the present invention include condensation compounds of monoamines or polyamines with carboxylic acids, and specific examples include compounds represented by the following general formula (b-1) or (b-2): [ka]

[0029] In the above general formula (b-1), R B1 is a hydrocarbon group. B2 and R B3 are each independently a hydrogen atom, a hydrocarbon group, or a hydrocarbon group substituted with a hydroxyl group.

[0030] In the above general formula (b-2), R B4 is a hydrogen atom, a hydrocarbon group, or a hydrocarbon group substituted with a hydroxyl group. Each X is independently a hydrogen atom or -(C=O)-R B5 An acyl group (R B5 is a hydrocarbon group), and at least one of the multiple Xs is the acyl group. b1 is an integer of 1 to 6. b2 is an integer of 1 or more, preferably an integer of 1 to 20.

[0031] R B1 , R B2 , R B3 , R B4 , and R B5 Examples of the hydrocarbon group that can be selected as the alkyl group include an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, and an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group having 1 to 6 carbon atoms.

[0032] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group (n-propyl group, isopropyl group), a butyl group (n-butyl group, s-butyl group, t-butyl group, isobutyl group), a pentyl group, a hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a hexadecyl group, and an octadecyl group. These alkyl groups may be straight-chain alkyl groups or branched-chain alkyl groups. The alkyl group has 1 to 30 carbon atoms, but may have 2 or more, 6 or more, 10 or more, 12 or more, 14 or more, or 16 or more carbon atoms, and may have 28 or less, 26 or less, 24 or less, 22 or less, or 20 or less carbon atoms.

[0033] Examples of the alkenyl group include ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, and octadecenyl groups. These alkenyl groups may be straight-chain alkenyl groups or branched-chain alkenyl groups. The alkenyl group has 2 to 30 carbon atoms, but may have 3 or more, 5 or more, 8 or more, 10 or more, 12 or more, 14 or more, or 16 or more carbon atoms, and may have 28 or less, 26 or less, 24 or less, 22 or less, or 20 or less carbon atoms.

[0034] Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a biphenyl group, a terphenyl group, and a phenylnaphthyl group, with a phenyl group being preferred. Examples of the "alkyl group having 1 to 6 carbon atoms" that can substitute for these aryl groups include the alkyl groups having 1 to 6 carbon atoms mentioned above.

[0035] Examples of the hydrocarbon group constituting the hydrocarbon group substituted with the hydroxyl group include the above-mentioned alkyl groups, alkenyl groups, and aryl groups, and the number of carbon atoms in the hydrocarbon group is preferably 1 to 30, more preferably 1 to 20, even more preferably 1 to 10, still more preferably 1 to 6, and particularly preferably 1 to 3. The number of hydroxyl groups in the hydroxyl-substituted hydrocarbon group may be one or more, but is preferably 1 to 6, more preferably 1 to 3, even more preferably 1 to 2, and still more preferably 1. In one embodiment of the present invention, the hydrocarbon group substituted with a hydroxyl group is preferably an alkyl group or alkenyl group substituted with a hydroxyl group, more preferably an alkyl group substituted with a hydroxyl group, and even more preferably an alkyl group having 1 to 6 carbon atoms substituted with a hydroxyl group.

[0036] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of improving metal corrosion resistance and providing a lubricating oil composition that can be suitably used for lubricating an internal combustion engine that uses a fuel containing ammonia, it is preferred that component (B) contains a glycolic acid amide (B1). The component (B1) used in one aspect of the present invention is R in the general formula (b-1). B1 is an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms, and R B2 is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, or an alkyl group having 1 to 30 carbon atoms substituted with a hydroxyl group, R B3 is preferably a glycolic acid amide in which R is an alkyl group having 1 to 30 carbon atoms substituted with a hydroxyl group, and B1 is an alkenyl group having 2 to 30 carbon atoms, and R B2 and R B3 are more preferably glycolic acid amides, each of which is independently an alkyl group having 1 to 30 carbon atoms substituted with a hydroxyl group.

[0037] In the lubricating oil composition of one embodiment of the present invention, the content of component (B1) in component (B) is preferably 50 mass% or more, 60 mass% or more, 70 mass% or more, 80 mass% or more, 90 mass% or more, 95 mass% or more, 97 mass% or more, 98 mass% or more, 99 mass% or more, or 100 mass% based on the total amount (100 mass%) of component (B) contained in the lubricating oil composition.

[0038] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of improving metal corrosion resistance and providing a lubricating oil composition that can be suitably used for lubricating internal combustion engines that use ammonia-containing fuel, the content of component (B) is preferably 0.01 mass% or more, 0.05 mass% or more, 0.10 mass% or more, 0.15 mass% or more, 0.20 mass% or more, 0.25 mass% or more, or 0.30 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, and is also preferably 5.00 mass% or less, 4.50 mass% or less, 4.00 mass% or less, 3.50 mass% or less, 3.00 mass% or less, 2.50 mass% or less, 2.00 mass% or less, 1.50 mass% or less, 1.20 mass% or less, 1.00 mass% or less, 0.80 mass% or less, or 0.60 mass% or less.

[0039] <Component (C): Metal deactivator> The lubricating oil composition of one embodiment of the present invention contains less than 0.30 mass% of a metal deactivator as component (C), which improves metal corrosion resistance and makes the lubricating oil composition suitable for use in lubricating internal combustion engines using fuels containing ammonia. In one embodiment of the present invention, the component (C) may be used alone or in combination of two or more types.

[0040] Examples of the component (C) used in one embodiment of the present invention include benzotriazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, tolyltriazole-based compounds, and pyrimidine-based compounds. Among these, from the viewpoint of further improving metal corrosion resistance and providing a lubricating oil composition that can be suitably used for lubricating an internal combustion engine using a fuel containing ammonia, it is preferable that component (C) used in one embodiment of the present invention contains a benzotriazole-based compound (C1).

[0041] In the lubricating oil composition of one embodiment of the present invention, the content of component (C1) in component (C) is preferably 50 mass% or more, 60 mass% or more, 70 mass% or more, 80 mass% or more, 90 mass% or more, 95 mass% or more, 97 mass% or more, 98 mass% or more, 99 mass% or more, or 100 mass% based on the total amount (100 mass%) of component (C) contained in the lubricating oil composition.

[0042] An example of the component (C1) used in one embodiment of the present invention is a compound represented by the following general formula (c-1). [ka]

[0043] In the general formula (c-1), R C1 is a hydrocarbon group which may contain at least one atom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom, or a hydrogen atom. R C are each independently a hydrocarbon group which may contain at least one atom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom. c1 is an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0044] Examples of the hydrocarbon group include an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, and a group formed by combining two or more of these groups. R C1The number of carbon atoms in the hydrocarbon group that can be selected as is preferably 1 or more, 3 or more, 6 or more, 8 or more, 10 or more, 12 or more, or 15 or more, and is preferably 30 or less, 28 or less, 26 or less, 24 or less, 22 or less, or 20 or less. R C The number of carbon atoms of the hydrocarbon group that can be selected as is preferably 1 to 20, 1 to 16, 1 to 12, 1 to 8, 1 to 6, 1 to 4, or 1 to 2.

[0045] The alkyl group, alkenyl group, and aryl group that can be selected as the hydrocarbon group include R B1 Examples of the alkyl group, alkenyl group, and aryl group that can be selected as the alkyl group include: Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and an adamantyl group.

[0046] R C1 and R C Examples of the hydrocarbon group containing at least one atom selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom that can be selected as above include groups represented by the following formulae (ci) to (c-iii). [ka]

[0047] In the general formulae (ci) to (c-iii), A c is a divalent hydrocarbon group, and R c11 and R c12 are each independently a monovalent hydrocarbon group. A cExamples of the divalent hydrocarbon group that can be selected as the alkylene group include an alkylene group having 1 to 20 carbon atoms (preferably 1 to 12, more preferably 1 to 8, even more preferably 1 to 4, still more preferably 1 to 2, and particularly preferably 1), an alkenylene group having 2 to 20 carbon atoms (preferably 2 to 12, more preferably 2 to 8, and even more preferably 2 to 4), a cycloalkylene group having 3 to 20 ring carbon atoms (preferably 3 to 15, more preferably 5 to 12, and even more preferably 5 to 6), and an arylene group having 6 to 30 ring carbon atoms (preferably 6 to 18, more preferably 6 to 15, and even more preferably 6 to 12). R c11 and R c12 Examples of the monovalent hydrocarbon group that can be selected include an alkyl group having 1 to 20 carbon atoms (preferably 1 to 16, more preferably 2 to 12, even more preferably 3 to 10, and still more preferably 4 to 8), an alkenyl group having 2 to 20 carbon atoms (preferably 2 to 16, more preferably 2 to 12, and even more preferably 2 to 10), a cycloalkyl group having 3 to 20 ring carbon atoms (preferably 3 to 15, more preferably 5 to 12, and even more preferably 5 to 6), and an aryl group having 6 to 30 ring carbon atoms (preferably 6 to 18, more preferably 6 to 15, and even more preferably 6 to 12).

[0048] The component (C) used in one embodiment of the present invention preferably contains a compound (C1) represented by the following general formula (c-2). [ka]

[0049] In the above general formula (c-2), R C and c1 is R in the general formula (c-1) above. C and c1, and the preferred embodiments of the groups are also the same. c , R c11 and R c12 represents A in the above general formula (c-iii). c , R c11 and R c12 and the preferred embodiments of the groups are also the same. In addition, a preferred embodiment of the compound (C1) is a compound represented by the general formula (c-2) above, wherein R C are each independently an alkyl group having 1 to 20 carbon atoms (preferably 1 to 16, more preferably 1 to 12, more preferably 1 to 8, even more preferably 1 to 6, still more preferably 1 to 4, and particularly preferably 1 to 2), and A c is an alkylene group having 1 to 20 carbon atoms (preferably 1 to 12, more preferably 1 to 8, even more preferably 1 to 4, still more preferably 1 to 2, and particularly preferably 1), and R c11 and R c12 are each independently an alkyl group having 1 to 20 carbon atoms (preferably 1 to 16, more preferably 2 to 12, even more preferably 3 to 10, and still more preferably 4 to 8). z1 is an integer of 0 to 4 (preferably an integer of 0 to 2, more preferably an integer of 0 to 1, and even more preferably 0).

[0050] In the lubricating oil composition of one embodiment of the present invention, the content of component (C) is adjusted to less than 0.30 mass% based on the total amount (100 mass%) of the lubricating oil composition, from the viewpoint of improving the effect of inhibiting discoloration of copper plates and the like that constitute components of internal combustion engines. From the above viewpoints, the content of component (C) is preferably 0.28 mass% or less, 0.26 mass% or less, 0.24 mass% or less, 0.22 mass% or less, 0.20 mass% or less, 0.18 mass% or less, 0.16 mass% or less, 0.14 mass% or less, 0.12 mass% or less, 0.10 mass% or less, less than 0.10 mass%, 0.09 mass%, 0.08 mass% or less, or 0.07 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition. Furthermore, from the viewpoint of providing a lubricating oil composition that can inhibit the elution of metals from copper plates and the like that constitute components of internal combustion engines, the content of component (C) is preferably 0.01 mass % or more, 0.02 mass % or more, 0.03 mass % or more, 0.04 mass % or more, or 0.05 mass % or more based on the total amount (100 mass %) of the lubricating oil composition.

[0051] In one embodiment of the lubricating oil composition of the present invention, from the viewpoint of suppressing discoloration and metal elution of copper plates and the like constituting components of internal combustion engines, improving metal corrosion resistance, and providing a lubricating oil composition that can be suitably used for lubricating internal combustion engines that use fuels containing ammonia, the content ratio of component (B) to component (C) [(B) / (C)], in mass ratio, is preferably 1.2 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, 4.0 or more, 4.5 or more, 5.0 or more, or 5.5 or more, and is preferably 10.0 or less, 9.5 or less, 9.0 or less, 8.5 or less, 8.0 or less, 7.5 or less, or 7.0 or less.

[0052] <Component (D): Organic zinc dithiophosphate> The lubricating oil composition of one embodiment of the present invention contains an organic zinc dithiophosphate (hereinafter also referred to as "ZnDTP") as component (D). By including component (D), it is possible to obtain a lubricating oil composition with improved metal corrosion resistance and wear resistance in a well-balanced manner. In one embodiment of the present invention, the component (D) may be used alone or in combination of two or more types.

[0053] Component (D) used in one embodiment of the present invention includes a compound represented by the following general formula (d-1). [ka]

[0054] In the above formula (d-1), R D1 ~R D4 are each independently a hydrocarbon group, and may be the same as or different from each other. R D1 ~R D4 The hydrocarbon group that can be selected as above preferably has 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, even more preferably 3 to 12 carbon atoms, and even more preferably 3 to 10 carbon atoms.

[0055] R D1 ~R D4Examples of the hydrocarbon group that can be selected as the above include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl; alkenyl groups such as octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, and pentadecenyl; cyclohexyl, dimethylcyclohexyl, ethylenediamine, ethylenediamine, ethylenediamine cycloalkyl groups such as ethylcyclohexyl group, methylcyclohexylmethyl group, cyclohexylethyl group, propylcyclohexyl group, butylcyclohexyl group, and heptylcyclohexyl group; aryl groups such as phenyl group, naphthyl group, anthracenyl group, biphenyl group, and terphenyl group; alkylaryl groups such as tolyl group, dimethylphenyl group, butylphenyl group, nonylphenyl group, methylbenzyl group, and dimethylnaphthyl group; and arylalkyl groups such as phenylmethyl group, phenylethyl group, and diphenylmethyl group. R D1 ~R D4 The hydrocarbon group that can be selected as is preferably an alkyl group, more preferably a primary or secondary alkyl group, and even more preferably a secondary alkyl group.

[0056] In one embodiment of the lubricating oil composition of the present invention, from the viewpoint of obtaining a lubricating oil composition having improved metal corrosion resistance and wear resistance in a balanced manner, the content of component (D) is, based on the total amount (100 mass%) of the lubricating oil composition, 0.01 mass% or more, 0.05 mass% or more, 0.10 mass% or more, 0.20 mass% or more, 0.30 mass% or more, 0.40 mass% or more, 0.45 mass% or more, 0.50 mass% or more, 0.55 mass% or more, 0.60 mass% or more, 0.65 mass% or more, 0.70 mass% or more, 0.75 mass% or more, or 0.80 mass% or more, and is 7.0 mass% or less, 6.0 mass% or less, 5.0 mass% or less, 4.0 mass% or less, 3.0 mass% or less, 2.0 mass% or less, 1.5 mass% or less, 1.2 mass% or less, 1.0 mass% or less, or 0.90 mass% or less.

[0057] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with improved metal corrosion resistance and wear resistance in a balanced manner, the content of component (D) in terms of zinc atoms is preferably 100 ppm by mass or more, 200 ppm by mass or more, 300 ppm by mass or more, 400 ppm by mass or more, 450 ppm by mass or more, 500 ppm by mass or more, 550 ppm by mass or more, 600 ppm by mass or more, or 650 ppm by mass or more, based on the total amount (100% by mass) of the lubricating oil composition, and is preferably 7000 ppm by mass or less, 6000 ppm by mass or less, 5000 ppm by mass or less, 4000 ppm by mass or less, 3000 ppm by mass or less, 2000 ppm by mass or less, 1500 ppm by mass or less, 1200 ppm by mass or less, 1000 ppm by mass or less, 900 ppm by mass or less, or 800 ppm by mass or less.

[0058] <Component (E): Calcium-based detergent> The lubricating oil composition of one embodiment of the present invention contains a calcium-based detergent as component (E). The inclusion of component (E) neutralizes sulfuric acid produced when marine hydrocarbon fuel is burned and nitrogen oxides produced when ammonia is burned, thereby providing a lubricating oil composition that can inhibit corrosion of metal materials constituting internal combustion engine components caused by sulfuric acid and nitrogen oxides. The component (E) used in one embodiment of the present invention may be used alone or in combination of two or more types.

[0059] Component (E) used in one embodiment of the present invention may be a neutral calcium-based detergent having a base number of less than 100 mgKOH / g, or may be an overbased calcium detergent having a base number of 100 mgKOH / g or more. However, from the viewpoint of providing a lubricating oil composition that can inhibit corrosion of metal materials constituting internal combustion engine components caused by sulfuric acid, it is preferable that the lubricating oil composition contain an overbased calcium detergent.

[0060] From the viewpoint of providing a lubricating oil composition that can inhibit corrosion of metal materials constituting members of internal combustion engines caused by sulfuric acid, the base number of component (E) used in one embodiment of the present invention is preferably 100 mgKOH / g or more, 120 mgKOH / g or more, 150 mgKOH / g or more, 170 mgKOH / g or more, 200 mgKOH / g or more, 220 mgKOH / g or more, 250 mgKOH / g or more, 270 mgKOH / g or more, 300 mgKOH / g or more, 320 mgKOH / g or more, or 340 mgKOH / g or more, and may also be 600 mgKOH / g or less, 550 mgKOH / g or less, 500 mgKOH / g or less, 450 mgKOH / g or less, or 400 mgKOH / g or less.

[0061] Examples of the component (E) used in one embodiment of the present invention include calcium phenate, calcium sulfonate, and calcium salicylate, with calcium salicylate being preferred. Examples of calcium phenates include compounds represented by the following general formula (e-1), examples of calcium sulfonates include compounds represented by the following general formula (e-2), and examples of calcium salicylates include compounds represented by the following general formula (e-3).

[0062] [ka]

[0063] In the above general formulas (e-1) to (e-3), R is a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms. The hydrocarbon group may be a straight-chain hydrocarbon group or a branched-chain hydrocarbon group. Examples of hydrocarbon groups that can be selected as R include alkyl groups having 1 to 18 carbon atoms, alkenyl groups having 1 to 18 carbon atoms, cycloalkyl groups having 3 to 18 ring carbon atoms, aryl groups having 6 to 18 ring carbon atoms, alkylaryl groups having 7 to 18 carbon atoms, and arylalkyl groups having 7 to 18 carbon atoms. y is an integer of 0 or more, preferably an integer of 0 to 3.

[0064] In one embodiment of the lubricating oil composition of the present invention, from the viewpoint of providing a lubricating oil composition that can inhibit corrosion of metal materials constituting members of internal combustion engines caused by sulfuric acid, the content of component (E) in terms of calcium atoms is, based on the total amount (100 mass%) of the lubricating oil composition, 5000 ppm by mass or more, 5200 ppm by mass or more, 5400 ppm by mass or more, 5600 ppm by mass or more, 5800 ppm by mass or more, 6000 ppm by mass or more, 6200 ppm by mass or more, 6400 ppm by mass or more, 6600 ppm by mass or more, 6800 ppm by mass or more, 7000 ppm by mass or more, 8000 ppm by mass or more, 9000 ppm by mass or more, 1000 ppm by mass or more, 1100 ppm by mass or more, 1200 ppm by mass or more, 1300 ppm by mass or more, 1400 ppm by mass or more, 1500 ppm by mass or more, 1600 ppm by mass or more, 1700 ppm by mass or more, 1800 ppm by mass or more, 1900 ppm by mass or more, 2000 ppm by mass or more, 2100 ppm by mass or more, 2200 ppm by mass or more, 2300 ppm by mass or more, 2400 ppm by mass or more, 2500 ppm by mass or more, 2600 ppm by mass or more, 2700 ppm by mass or more, 2800 ppm by mass or more, 2900 ppm by mass or more, 3000 ppm by mass or more, 3100 ppm by mass or more, 3200 ppm by mass or more, 3300 ppm by mass or more, 3400 ppm by mass or more, 3500 ppm by mass pm or more, or 7200 ppm by mass or more, and from the viewpoint of obtaining a lubricating oil composition that can suppress the amount of deposits generated and the occurrence of scratching wear, and from the viewpoint of obtaining a lubricating oil composition with good metal corrosion resistance, it is preferable that the content be 9000 ppm by mass or less, 8500 ppm by mass or less, 8000 ppm by mass or less, 7800 ppm by mass or less, 7600 ppm by mass or less, 7400 ppm by mass or less, 7200 ppm by mass or less, 7000 ppm by mass or less, 6500 ppm by mass or less, or 6000 ppm by mass or less.

[0065] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition that can inhibit corrosion of metal materials that constitute components of internal combustion engines caused by sulfuric acid, the content of component (E) is preferably 2.0 mass% or more, 2.5 mass% or more, 3.0 mass% or more, 3.5 mass% or more, 4.0 mass% or more, 4.5 mass% or more, 5.0 mass% or more, 5.5 mass% or more, 5.7 mass% or more, or 6.0 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition. Furthermore, from the viewpoint of providing a lubricating oil composition that can inhibit the amount of deposits generated and the occurrence of scratching wear, and from the viewpoint of providing a lubricating oil composition with good metal corrosion resistance, the content of component (E) is preferably 12.0 mass% or less, 11.0 mass% or less, 10.0 mass% or less, 9.0 mass% or less, 8.0 mass% or less, 7.0 mass% or less, 6.5 mass% or less, 6.0 mass% or less, 5.5 mass% or less, or 5.0 mass% or less.

[0066] <Other metal-based detergents> The lubricating oil composition of one embodiment of the present invention may contain metal-based detergents other than calcium, as long as the effects of the present invention are not impaired. Other metal-based detergents include sodium-based detergents such as sodium phenate, sodium sulfonate, and sodium salicylate; and magnesium-based detergents such as magnesium phenate, magnesium sulfonate, and magnesium salicylate.

[0067] In the lubricating oil composition of one embodiment of the present invention, the content of each of the sodium-based detergent and the magnesium-based detergent, calculated as metal atoms, may be less than 1000 ppm by mass, less than 500 ppm by mass, less than 100 ppm by mass, less than 50 ppm by mass, less than 40 ppm by mass, less than 30 ppm by mass, 20 ppm by mass or less, less than 10 ppm by mass, less than 1.0 ppm by mass, less than 100 ppb by mass, less than 10 ppb by mass, or less than 1.0 ppb by mass, based on the total amount (100% by mass) of the lubricating oil composition.

[0068] In the lubricating oil composition of one embodiment of the present invention, the content of each of the sodium-based detergent and the magnesium-based detergent may be less than 10.0 mass%, less than 5.0 mass%, less than 2.0 mass%, less than 1.0 mass%, less than 0.1 mass%, less than 0.01 mass%, less than 0.001 mass%, less than 0.0001 mass%, or less than 0.00001 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0069] In the lubricating oil composition of one embodiment of the present invention, the content of the sodium-based detergent or magnesium-based detergent may be less than 50 parts by mass, less than 20 parts by mass, less than 10 parts by mass, less than 5.0 parts by mass, less than 1.0 part by mass, less than 0.1 part by mass, less than 0.01 part by mass, or less than 0.001 part by mass, relative to 100 parts by mass of the total amount of component (E) contained in the lubricating oil composition.

[0070] <Ingredient (F): Antioxidant> The lubricating oil composition of one embodiment of the present invention may further contain an antioxidant. By containing component (F), it is possible to obtain a lubricating oil composition that can inhibit sludge deposition. In one embodiment of the present invention, the component (F) may be used alone or in combination of two or more types.

[0071] Examples of component (F) used in one embodiment of the present invention include amine-based antioxidants such as alkylated diphenylamine, phenylnaphthylamine, and alkylated phenylnaphthylamine; phenol-based antioxidants such as 2,6-di-t-butylphenol, 4,4'-methylenebis(2,6-di-t-butylphenol), isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; and sulfur-based antioxidants such as phenothiazine, dioctadecyl sulfide, dilauryl-3,3'-thiodipropionate, and 2-mercaptobenzimidazole. Among these, the component (F) used in one embodiment of the present invention preferably contains an amine-based antioxidant (F1). As the amine-based antioxidant (F1), alkylated diphenylamines are preferred, and compounds represented by the following general formula (f-1) are more preferred. [ka]

[0072] In the above general formula (f-1), R F1 and R F2 are each independently an alkyl group. f1 and f2 are each independently an integer of 1 to 5, preferably an integer of 1 to 3, more preferably 1 or 2, and further preferably 1. R F1 and R F2 Examples of the alkyl group that can be selected as the alkyl group include a methyl group, an ethyl group, a propyl group (n-propyl group, isopropyl group), a butyl group (n-butyl group, s-butyl group, t-butyl group, isobutyl group), a pentyl group, a hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a hexadecyl group, and an octadecyl group. R F1 and R F2 The number of carbon atoms in the alkyl group that can be selected as is preferably 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, or 9 or more, and is preferably 20 or less, 18 or less, 16 or less, 14 or less, 12 or less, or 10 or less.

[0073] In the lubricating oil composition of one embodiment of the present invention, the content of component (F1) in component (F) is preferably 20 mass% or more, 30 mass% or more, 40 mass% or more, 50 mass% or more, 60 mass% or more, 70 mass% or more, 80 mass% or more, 90 mass% or more, 95 mass% or more, or 100 mass% based on the total amount (100 mass%) of component (C) contained in the lubricating oil composition.

[0074] In the lubricating oil composition of one embodiment of the present invention, the content of component (F) is preferably 0.01 mass% or more, 0.05 mass% or more, 0.10 mass% or more, 0.15 mass% or more, 0.20 mass% or more, 0.25 mass% or more, or 0.30 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, and is preferably 10.0 mass% or less, 7.0 mass% or less, 5.0 mass% or less, 4.0 mass% or less, 3.0 mass% or less, 2.0 mass% or less, 1.5 mass% or less, 1.0 mass% or less, or 0.80 mass% or less.

[0075] In the lubricating oil composition of one embodiment of the present invention, the content of component (F1) calculated as nitrogen atoms is preferably 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, 70 ppm by mass or more, 80 ppm by mass or more, 90 ppm by mass or more, or 100 ppm by mass or more, based on the total amount (100% by mass) of the lubricating oil composition, and is preferably 1000 ppm by mass or less, 800 ppm by mass or less, 600 ppm by mass or less, 500 ppm by mass or less, 400 ppm by mass or less, 300 ppm by mass or less, 250 ppm by mass or less, 200 ppm by mass or less, or 150 ppm by mass or less. In this specification, the nitrogen atom content refers to a value measured in accordance with JIS K2609:1998.

[0076] <Component (G): Imide-based compound> The lubricating oil composition of one embodiment of the present invention may contain an imide-based compound as component (G). By containing component (G), it is possible to obtain a lubricating oil composition that can inhibit sludge deposition. In one embodiment of the present invention, the component (G) may be used alone or in combination of two or more types.

[0077] In this specification, the term "imide-based compound" refers to a compound having an imide structure represented by the following formula (g-0), and includes a chain compound having the imide structure and a cyclic compound having the imide structure. [ka] (In the above formula, * indicates the bond position.)

[0078] Component (G) used in one embodiment of the present invention may be a modified imide-based compound reacted with one or more compounds selected from the group consisting of boron compounds, alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, and organic acids, or may be a non-modified imide-based compound.

[0079] Component (G) used in one embodiment of the present invention preferably contains one or more selected from alkenyl succinimides and modified products thereof, and more preferably contains one or more selected from non-boron-modified alkenyl succinimides (G1) and boron-modified alkenyl succinimides (G2).

[0080] The total content of components (G1) and (G2) in component (G) used in one embodiment of the present invention is preferably 60 to 100 mass%, more preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 85 to 100 mass%, still more preferably 90 to 100 mass%, and particularly preferably 95 to 100 mass%, based on the total amount (100 mass%) of component (G) contained in the lubricating oil composition.

[0081] The non-boron-modified alkenyl succinimide (G1) is preferably at least one selected from the group consisting of alkenyl succinic acid bisimides (G11) represented by the following general formula (g-1) and alkenyl succinic acid monoimides (G12) represented by the following general formula (g-2). [ka]

[0082] In the above general formulas (g-1) and (g-2), R G1 , R G2 and R G3 are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 3000 (preferably 900 to 2500). R G1 , R G2 and R G3 Examples of the alkenyl group that can be selected as include a polybutenyl group, a polyisobutenyl group, an ethylene-propylene copolymer, and the like. Among these, a polybutenyl group or a polyisobutenyl group is preferred. A G1 , A G2 and A G3 are each independently an alkylene group having 2 to 5 carbon atoms. z1 is an integer of 0 to 10, preferably an integer of 1 to 4, and more preferably 2 or 3. z2 is an integer of 1 to 10, preferably an integer of 2 to 5, and more preferably 3 or 4.

[0083] Examples of the boron-modified alkenyl succinimide (G2) used in one embodiment of the present invention include a boron-modified alkenyl succinic acid bisimide represented by the general formula (g-1) above and a boron-modified alkenyl succinic acid monoimide represented by the following general formula (g-2):

[0084] In the lubricating oil composition of one embodiment of the present invention, the content of component (G) is preferably 0.10 mass% or more, 0.50 mass% or more, 1.0 mass% or more, 1.2 mass% or more, 1.5 mass% or more, or 1.7 mass% or more, based on the total amount (100 mass%) of the lubricating oil composition, and is preferably 10.0 mass% or less, 8.0 mass% or less, 6.0 mass% or less, 5.0 mass% or less, or 4.0 mass% or less.

[0085] <Lubricant additives> The lubricating oil composition of one embodiment of the present invention may further contain lubricating oil additives other than components (B) to (G) as needed, provided that the effects of the present invention are not impaired. Examples of such lubricating oil additives include pour point depressants, viscosity index improvers, friction modifiers, anti-wear agents, extreme pressure agents, oiliness agents, rust inhibitors, and anti-foaming agents. These lubricating oil additives may be used alone or in combination of two or more.

[0086] The content of each of the above lubricating oil additives can be adjusted as appropriate within a range that does not impair the effects of the present invention, and is typically 0.001 to 15 mass%, preferably 0.005 to 10 mass%, and more preferably 0.01 to 5 mass%, for each additive, based on the total amount (100 mass%) of the lubricating oil composition.

[0087] Furthermore, the lubricating oil composition of one embodiment of the present invention may have limited contents of the lubricating oil additives, and the content of each of the lubricating oil additives may be less than 5.0 mass%, less than 2.0 mass%, less than 1.0 mass%, less than 0.1 mass%, less than 0.01 mass%, less than 0.001 mass%, less than 0.0001 mass%, or less than 0.00001 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0088] [Pour point depressants] The lubricating oil composition of one embodiment of the present invention may further contain a pour point depressant. The pour point depressants may be used alone or in combination of two or more. Examples of pour point depressants used in one embodiment of the present invention include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, and polyalkylstyrenes. The weight average molecular weight (Mw) of the pour point depressant used in one embodiment of the present invention may be 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, 20,000 or more, 25,000 or more, 30,000 or more, 35,000 or more, 40,000 or more, 45,000 or more, 50,000 or more, 55,000 or more, or 60,000 or more, and may be 150,000 or less, 120,000 or less, 100,000 or less, 90,000 or less, or 80,000 or less.

[0089] [Viscosity index improver] The lubricating oil composition of one embodiment of the present invention may further contain a viscosity index improver. The viscosity index improvers may be used alone or in combination of two or more. Examples of viscosity index improvers used in one embodiment of the present invention include polymers such as non-dispersant polymethacrylate, dispersant polymethacrylate, olefin copolymers (e.g., ethylene-propylene copolymers), dispersant olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers). The mass average molecular weight (Mw) of the viscosity index improver used in one embodiment of the present invention may be 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, or 20,000 or more, and may be 1,000,000 or less, 700,000 or less, 500,000 or less, 300,000 or less, 200,000 or less, 100,000 or less, or 50,000 or less.

[0090] [Friction modifiers and anti-wear agents] The lubricating oil composition of one embodiment of the present invention may further contain a friction modifier or an anti-wear agent. The friction modifier or anti-wear agent may be used alone or in combination of two or more kinds. Examples of friction modifiers and anti-wear agents used in one embodiment of the present invention include sulfur-based compounds such as sulfurized olefins, dialkyl polysulfides, diaryl alkyl polysulfides, and diaryl polysulfides; phosphorus-based compounds such as phosphate esters, thiophosphate esters, phosphites, alkyl hydrogen phosphites, phosphate ester amine salts, and phosphites ester amine salts; and ashless friction modifiers such as fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea-based compounds, and hydrazide-based compounds.

[0091] [Extreme pressure agents] The lubricating oil composition of one embodiment of the present invention may further contain an extreme pressure agent. The extreme pressure agents may be used alone or in combination of two or more. Examples of extreme pressure agents used in one embodiment of the present invention include sulfur-based compounds such as sulfurized olefins, dialkyl polysulfides, diaryl alkyl polysulfides, and diaryl polysulfides; and phosphorus-based compounds such as phosphate esters, thiophosphate esters, phosphite esters, alkyl hydrogen phosphites, phosphate ester amine salts, and phosphite ester amine salts.

[0092] [Oil-based agent] The lubricating oil composition of one embodiment of the present invention may further contain an oiliness agent. The oiliness agents may be used alone or in combination of two or more. Examples of oily agents used in one embodiment of the present invention include saturated and unsaturated aliphatic monocarboxylic acids such as stearic acid and oleic acid, polymerized fatty acids such as dimer acid and hydrogenated dimer acid, hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid, saturated and unsaturated aliphatic monoalcohols such as lauryl alcohol and oleyl alcohol, saturated and unsaturated aliphatic monoamines such as stearylamine and oleylamine, and saturated and unsaturated aliphatic monocarboxylic acid amides such as lauric acid amide and oleic acid amide.

[0093] [Rust inhibitor] The lubricating oil composition of one embodiment of the present invention may further contain a rust inhibitor. The rust inhibitor may be used alone or in combination of two or more kinds. Examples of the rust inhibitor used in one embodiment of the present invention include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, and alkyl polyoxyethylene ethers.

[0094] [Antifoaming agent] The lubricating oil composition of one embodiment of the present invention may further contain an antifoaming agent. The antifoaming agents may be used alone or in combination of two or more. Examples of the defoaming agent used in one embodiment of the present invention include alkylsilicone-based defoaming agents, fluorosilicone-based defoaming agents, and fluoroalkyl ether-based defoaming agents.

[0095] <Method of manufacturing lubricating oil composition> There are no particular limitations on the method for producing the lubricating oil composition of one embodiment of the present invention, but from the viewpoint of productivity, it is preferred that the method comprises a step of blending the above-mentioned components (B) to (E) with base oil (A), as well as components (F) to (G) and other lubricating oil additives, as necessary.

[0096] [Properties of lubricating oil composition] The kinematic viscosity at 40°C of the lubricating oil composition of one embodiment of the present invention is 100mm 2 / s or more, 110mm 2 / s or more, 115mm 2 / s or more, 120mm 2 / s or more, 125mm 2 / s or more, or 130 mm 2 / s or more is preferable, and 2 / s or less, 500mm 2 / s or less, 400mm 2 / s or less, 350mm 2 / s or less, 300mm 2 / s or less, 250mm 2 / s or less, or 200 mm2 It is preferable to set it to / s or less.

[0097] The kinematic viscosity at 100°C of the lubricating oil composition of one embodiment of the present invention is 6.0 mmHg, from the viewpoint of making the lubricating oil composition suitable for lubricating marine engines. 2 / s or more, 7.0mm 2 / s or more, 8.0mm 2 / s or more, 9.0mm 2 / s or more, 10.0mm 2 / s or more, 11.0mm 2 / s or more, 12.0mm 2 / s or more, 13.0mm 2 / s or more, or 14.0 mm 2 / s or more, and 50.0 mm 2 / s or less, 40.0mm 2 / s or less, 30.0mm 2 / s or less, 25.0mm 2 / s or less, 20.0mm 2 / s or less, 18.0mm 2 / s or less, or 16.0 mm 2 It is preferable to set it to / s or less.

[0098] The viscosity index of the lubricating oil composition of one embodiment of the present invention is preferably 90 or greater, 95 or greater, 100 or greater, 105 or greater, or 110 or greater.

[0099] The calcium atom content in the lubricating oil composition of one embodiment of the present invention, based on the total amount (100% by mass) of the lubricating oil composition, is 5000 ppm by mass or more, 5200 ppm by mass or more, 5400 ppm by mass or more, 5600 ppm by mass or more, 5800 ppm by mass or more, 6000 ppm by mass or more, 6200 ppm by mass or more, 6400 ppm by mass or more, 6600 ppm by mass or more, 6800 ppm by mass or more, 7000 ppm by mass or more, from the perspective of providing a lubricating oil composition that can inhibit corrosion of metal materials constituting members of internal combustion engines caused by sulfuric acid and nitrogen oxides. or 7200 ppm by mass or more, and from the viewpoint of obtaining a lubricating oil composition that can suppress the amount of deposits generated and the occurrence of scratching wear, and from the viewpoint of obtaining a lubricating oil composition with good metal corrosion resistance, the content is preferably 9000 ppm by mass or less, 8500 ppm by mass or less, 8000 ppm by mass or less, 7800 ppm by mass or less, 7600 ppm by mass or less, 7400 ppm by mass or less, 7200 ppm by mass or less, 7000 ppm by mass or less, 6500 ppm by mass or less, or 6000 ppm by mass or less.

[0100] From the viewpoint of obtaining a lubricating oil composition that exhibits a well-balanced improvement in metal corrosion resistance and wear resistance, the content of zinc atoms in the lubricating oil composition of one embodiment of the present invention is preferably 100 ppm by mass or more, 200 ppm by mass or more, 300 ppm by mass or more, 400 ppm by mass or more, 450 ppm by mass or more, 500 ppm by mass or more, 550 ppm by mass or more, 600 ppm by mass or more, or 650 ppm by mass or more, based on the total amount (100% by mass) of the lubricating oil composition, and is preferably 7000 ppm by mass or less, 6000 ppm by mass or less, 5000 ppm by mass or less, 4000 ppm by mass or less, 3000 ppm by mass or less, 2000 ppm by mass or less, 1500 ppm by mass or less, 1200 ppm by mass or less, 1000 ppm by mass or less, 900 ppm by mass or less, or 800 ppm by mass or less.

[0101] The sodium atom content of the lubricating oil composition of one embodiment of the present invention may be, based on the total amount (100% by mass) of the lubricating oil composition, less than 1000 ppm by mass, less than 500 ppm by mass, less than 100 ppm by mass, less than 50 ppm by mass, less than 40 ppm by mass, less than 30 ppm by mass, 20 ppm by mass or less, less than 10 ppm by mass, less than 1.0 ppm by mass, less than 100 ppb by mass, less than 10 ppb by mass, or less than 1.0 ppb by mass.

[0102] The magnesium atom content of the lubricating oil composition of one embodiment of the present invention may be, based on the total amount (100% by mass) of the lubricating oil composition, less than 1000 ppm by mass, less than 500 ppm by mass, less than 100 ppm by mass, less than 50 ppm by mass, less than 40 ppm by mass, less than 30 ppm by mass, 20 ppm by mass or less, less than 10 ppm by mass, less than 1.0 ppm by mass, less than 100 ppb by mass, less than 10 ppb by mass, or less than 1.0 ppb by mass.

[0103] The content of molybdenum atoms in the lubricating oil composition of one embodiment of the present invention may be, based on the total amount (100% by mass) of the lubricating oil composition, less than 1000 ppm by mass, less than 500 ppm by mass, less than 100 ppm by mass, less than 50 ppm by mass, less than 40 ppm by mass, less than 30 ppm by mass, 20 ppm by mass or less, less than 10 ppm by mass, less than 1.0 ppm by mass, less than 100 ppb by mass, less than 10 ppb by mass, or less than 1.0 ppb by mass.

[0104] When a copper plate corrosion test is conducted on the lubricating oil composition of one embodiment of the present invention by the method described in the Examples below, the amount of copper eluted is preferably 30 ppm by mass or less, more preferably 28 ppm by mass or less, even more preferably 26 ppm by mass or less, still more preferably 24 ppm by mass or less, and particularly preferably 20 ppm by mass or less. Furthermore, after a copper plate corrosion test is conducted by the method described in the Examples below, the discoloration number of the copper plate according to "Table 1: Classification of corrosion according to copper plate corrosion standards" of JIS K2513 is preferably 1(a) or 1(b), more preferably 1(a). The specific procedures and conditions for the copper plate corrosion test are as described in the Examples below.

[0105] [Uses of lubricating oil composition] The lubricating oil composition of one embodiment of the present invention has excellent metal corrosion resistance and can therefore be suitably used for lubricating internal combustion engines that use fuels containing ammonia, and in particular, can be suitably used for lubricating marine engines that use fuels containing ammonia and marine hydrocarbon fuel.

[0106] Considering the above-mentioned properties of the lubricating oil composition of one embodiment of the present invention, the present invention can also provide the following [I] and [II]. [I] A marine engine that uses a fuel containing ammonia and is filled with the lubricating oil composition according to one embodiment of the present invention. [II] A method for lubricating a marine engine, comprising applying the lubricating oil composition according to one embodiment of the present invention to a marine engine that uses a fuel containing ammonia. The vessels described in [I] and [II] above may be inland vessels or open-air vessels, and the fuel may be a fuel containing ammonia and marine hydrocarbon fuel. [Example]

[0107] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are as follows.

[0108] (1) Kinematic viscosity and viscosity index Measurements and calculations were made in accordance with JIS K2283:2000. (2) Base number (perchloric acid method) Measurements were performed in accordance with "9. Potentiometric titration method (perchloric acid method)" of JIS K2501 "Petroleum products and lubricants - Testing method for neutralization number." (3) Content of calcium atoms (Ca), zinc atoms (Zn), sodium atoms (Na), magnesium atoms (Mg), and molybdenum atoms (Mo) Measurements were performed in accordance with JPI-5S-38-92. (4) Nitrogen atom (N) content Measurement was carried out in accordance with JIS K2609:1998. (5) Sulfated ash content Measurement was carried out in accordance with JIS K2272:1998.

[0109] Examples 1 to 4, Comparative Examples 1 to 10 Lubricating oil compositions were prepared by adding and mixing the base oil and various additives in the amounts shown in Tables 2 and 3. Details of the components used in preparing the lubricating oil compositions are as follows:

[0110] <Base oil> "Base oil (a-1)": Base oil classified as Group I of the API base oil category, kinematic viscosity at 40°C = 90.48 mm 2 / s, viscosity index=104. "Base oil (a-2)": Base oil classified as Group I of the API base oil category, kinematic viscosity at 40°C = 435.1 mm 2 / s, viscosity index=107. <Various additives> "Fatty acid amide": oleic acid diethanolamide Metal deactivator: 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole "Secondary ZnDTP": R in the general formula (d-1) d1 ~R d4 The organic zinc dithiophosphate is a secondary alkyl group, and the Zn content is 7.99% by mass. "Ca-based metal cleaning agent": Calcium salicylate with a base number of 350 mg KOH / g and a Ca content of 12.1% by mass. "Antioxidant": Bis(nonylphenyl)amine, N content = 3.61% by mass. · "Imide-based compounds": boron-modified alkenyl succinimides. "Antifoaming agent-containing solution": An antifoaming agent-containing solution obtained by diluting an antifoaming agent with a diluent oil.

[0111] The kinematic viscosity at 40°C and 100°C, viscosity index, base number, Ca and Zn contents, and sulfated ash content of the prepared lubricating oil compositions were measured or calculated, and the following corrosivity test was also carried out. The results are shown in Tables 2 and 3. In the prepared lubricating oil compositions, the magnesium atom (Mg) content was 20 ppm by mass or less, and the sodium atom (Na) and molybdenum atom (Mo) contents were both less than 5 ppm by mass.

[0112] [Corrosion test] Fuel containing ammonia Lubricating oil compositions used in internal combustion engines using fuels containing ammonia are more susceptible to corrosion of the components of the engine due to combustion than those using general hydrocarbon fuels, due to the fuel characteristics of the lubricating oil compositions, and therefore require higher corrosion resistance. Therefore, corrosion tests were conducted using the following procedure to evaluate the corrosion resistance to copper, which is also applicable to internal combustion engines using fuels containing ammonia. (i) Sample preparation The lubricating oil compositions prepared in the examples and comparative examples were aged in accordance with the ISOT (JIS K2514) test at an oil temperature of 165.5°C, a rotation speed of 1300 rpm, and for 48 hours to prepare sample oils. (ii) Corrosion resistance evaluation Corrosion tests were conducted in accordance with ASTM D6594 using the sample oils prepared in (i) above. The amount of copper (Cu) eluted was measured, and the discoloration of the copper plate after the test was observed. The corrosion resistance of the copper plate was evaluated based on "Table 1: Classification of Corrosion by Copper Plate Corrosion Standard" of JIS K2513, as shown in Table 1 below. The amount of copper elution was measured in accordance with JPI-5S-44-11. In Table 1, the "discoloration number (subdivision symbol)" is used. The smaller the number, the lower the copper corrosion resistance, and the alphabetical order indicates the degree of corrosion. In this test, if the amount of copper (Cu) eluted into the test oil was 30 ppm by mass or less and the copper plate discoloration was 1(a) or 1(b), the lubricating oil composition was determined to have excellent copper corrosion resistance and to be suitable for use in internal combustion engines using ammonia-containing fuel.

[0113] [Table 1]

[0114] [Table 2]

[0115] [Table 3]

[0116] As can be seen from Tables 2 to 3, the lubricating oil compositions prepared in Examples 1 to 4 reduced the amount of copper eluted and the discoloration of the copper plate in the copper corrosion test compared to the lubricating oil compositions of Comparative Examples 1 to 10, resulting in excellent metal corrosion resistance.

Claims

1. A lubricating oil composition comprising a base oil (A), an amide-based compound (B), a metal deactivator (C), an organic zinc dithiophosphate (D), and a calcium-based detergent (E), The content of component (C) is less than 0.30 mass% based on the total amount of the lubricating oil composition, The content of component (E) in terms of calcium atoms is 5000 ppm by mass or more based on the total amount of the lubricating oil composition, The base number of the lubricating oil composition is 10.0 mgKOH / g or more, The sulfated ash content of the lubricating oil composition is greater than 1.10 mass%. A lubricating oil composition for use in lubricating marine engines that use fuels containing ammonia.

2. The kinematic viscosity of the lubricating oil composition at 40°C is 100 mm ２ 2. The lubricating oil composition of claim 1, wherein the .gamma.-to-.alpha ...beta.

3. 3. The lubricating oil composition of claim 1, wherein component (B) comprises a fatty acid amide (D1).

4. The lubricating oil composition according to any one of claims 1 to 3, wherein the content of component (B) is 0.01 to 5.00 mass% based on the total amount of the lubricating oil composition.

5. The lubricating oil composition according to any one of claims 1 to 4, wherein component (C) comprises at least one compound selected from the group consisting of thiadiazole-based compounds, benzotriazole-based compounds, and tolyltriazole-based compounds.

6. The lubricating oil composition according to any one of claims 1 to 5, wherein the content of component (D) in terms of zinc atoms is 100 to 7000 ppm by mass based on the total amount of the lubricating oil composition.

7. The lubricating oil composition according to any one of claims 1 to 6, further comprising an antioxidant (F).

8. 8. The lubricating oil composition of claim 7, wherein component (F) comprises at least one selected from the group consisting of phenolic antioxidants and amine antioxidants.

9. The lubricating oil composition according to any one of claims 1 to 8, further comprising an imide-based compound (G).

10. The lubricating oil composition according to any one of claims 1 to 9, wherein the lubricating oil composition has a base number of 12.0 to 30.0 mgKOH / g.

11. A method for lubricating a marine engine, comprising applying the lubricating oil composition according to any one of claims 1 to 10 to lubricate the marine engine using a fuel containing ammonia.

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