Lubricating oil composition

Abstract

A lubricating oil composition having excellent separation property (anti-emulsification property) against water is sought. A lubricating oil composition for an internal combustion engine operating on hydrogen fuel, the lubricating oil composition containing: a base oil (A), a calcium-based detergent (B), a polyoxyalkylene glycol compound (C) represented by the following general formula (1), and one or more imide compounds (D) selected from the group consisting of compounds represented by the following general formulae (2) and (3), in the polyoxyalkylene glycol compound (C), the content of EO units is 65 mol% or less relative to the total amount of EO units and PO units, and the content of the imide compound (D) is 1.50 mass% or more.

Description

Technical Field

[0001] This invention relates to lubricating oil compositions. Background Technology

[0002] As an internal combustion engine used in automobiles and the like, technological development is underway for an internal combustion engine that operates using hydrogen as fuel (hereinafter also referred to as a "hydrogen fuel engine") (for example, Patent Document 1). In a hydrogen fuel engine, water is produced because hydrogen is used as fuel. It can be assumed that the produced water is discharged to the outside of the vehicle, but when this water mixes with the lubricating oil composition, the lubricating oil composition sometimes emulsifies, making it difficult for the water to be discharged.

[0003] Existing technical documents Patent documents Patent document 1: Japanese Patent Application Publication No. 2008-137505. Summary of the Invention

[0004] The problem the invention aims to solve In view of this situation, there is a need for lubricating oil compositions that exhibit superior water separability (hereinafter also referred to as "demulsibility").

[0005] Solution for solving the problem The inventors have conducted repeated and in-depth research and discovered that the above-mentioned problems can be solved by blending a calcium-based detergent, a polyoxyalkylene glycol compound with a specific structure, and a specified amount of an imide compound with a specific structure into the lubricating oil composition. Specifically, the present invention discloses the following methods.

[0006] [1] A lubricating oil composition for use in an internal combustion engine that operates on hydrogen fuel, the lubricating oil composition comprising: a base oil (A), a calcium detergent (B), a polyoxyalkylene glycol compound of general formula (1) below (C), and one or more imide compounds selected from compounds of general formulas (2) and (3) below (D). In the polyoxyalkylene glycol compound (C), the content of EO units relative to the total amount of EO units and PO units is less than 65 mol%. The content of imide compound (D) is 1.50% by mass or more.

[0007] [Chemistry 1] (In the aforementioned general formula (1), E represents ethylene, and P represents propylene. a and c are each independently a number greater than or equal to 0. b is a number greater than or equal to 1.) [Chemistry 2] (In the aforementioned general formulas (2) and (3), R) A RA1 and R A2 Each is an alkenyl group with a weight-average molecular weight of 500–4,000. R B R B1 and R B2 Each is an alkylene group with 2 to 5 carbon atoms. X1 and X2 are each an integer from 1 to 10. [2] The lubricating oil composition according to [1], wherein the calcium detergent (B) comprises calcium salicylate (B1).

[0008] [3] The lubricating oil composition according to [1] or [2], wherein the calcium detergent (B) is substantially free of calcium sulfonate (B2) and calcium phenolate (B3).

[0009] [4] The lubricating oil composition according to any one of [1] to [3], wherein the content of calcium detergent (B) is 0.10 to 10.0% by mass.

[0010] [5] The lubricating oil composition according to any one of [1] to [4], wherein the content of polyoxyalkylene glycol compound (C) is 0.001% to 0.1% by mass.

[0011] [6] The lubricating oil composition according to any one of [1] to [5], wherein the content of imide compound (D) is 10.0% by mass or less.

[0012] [7] The lubricating oil composition according to any one of [1] to [6] further contains one or more imide compounds (E) selected from the compounds shown in the following general formulas (4) and (5).

[0013] [Chemistry 3] (In the aforementioned general formulas (4) and (5), R) A R A1 and R A2 Each is an alkenyl group with a weight-average molecular weight of 500–4,000. R B R B1 and R B2 Each is an alkylene group having 2 to 5 carbon atoms. R C It is an alkyl group with 1 to 10 carbon atoms or a group represented by -(AO)nH (where A represents an alkylene group with 2 to 4 carbon atoms, and n represents an integer from 1 to 10). X1 and X2 are each independently an integer from 1 to 10. [8] The lubricating oil composition according to any one of [1] to [7], wherein the content ratio of calcium detergent (B) to polyoxyalkylene glycol compound (C) [component (C) / component (B)] is 0.15 or less by mass.

[0014] [9] The lubricating oil composition according to any one of [1] to [8], wherein the content ratio of polyoxyalkylene glycol compound (C) to imide compound (D) [component (C) / component (D)] is 0.10 or less by mass.

[0015]

[10] The lubricating oil composition according to any one of [1] to [9], wherein the content ratio of imide compound (D) to imide compound (E) [component (D) / component (E)] is 10.0 or less by mass.

[0016] Invention Effects A suitable embodiment of the present invention provides a lubricating oil composition having excellent demulsibility. Therefore, the lubricating oil composition of a suitable embodiment of the present invention can be suitably used, for example, in internal combustion engines operating on hydrogen fuel. Detailed Implementation

[0017] The upper and lower limits of the numerical ranges described in this specification can be combined arbitrarily. For example, when the numerical range is described as "preferably 30 to 100, more preferably 40 to 80", the range of "30 to 80" and the range of "40 to 100" are also included in the numerical ranges described in this specification.

[0018] Furthermore, when a numerical range is specified 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 specified in this specification. In other words, the numerical range from the lower limit to the upper limit can be specified by appropriately selecting and arbitrarily combining various options.

[0019] Furthermore, the numerical range described in this specification, such as "60~100", means the range of "60 or more (60 or more) and 100 or less (100 or less)".

[0020] Furthermore, the various conditions described as preferred embodiments in this specification can be combined in multiple ways.

[0021] [Composition of the lubricating oil composition] The lubricating oil composition of the present invention contains: base oil (A) (hereinafter also referred to as "component (A)"), calcium detergent (B) (hereinafter also referred to as "component (B)"), polyoxyalkylene glycol compound (C) of general formula (1) (hereinafter also referred to as "component (C)"), and one or more imide compounds (D) selected from the compounds of general formulas (2) and (3) (hereinafter also referred to as "component (D)").

[0022] In this invention, to address the problem of emulsification of the lubricating oil composition caused by the mixing of water generated in a hydrogen fuel engine, the demulsification performance is improved by blending a polyoxyalkylene glycol compound (C) with a specific structure and a specified amount of an imide compound (D) with a specific structure.

[0023] Therefore, the lubricating oil composition of the present invention can drain water, and even if water is mixed in and emulsification occurs, the lubricity will not be significantly impaired. Therefore, it can be suitable for use in hydrogen fuel engines.

[0024] It should be noted that, within the scope of the present invention, the lubricating oil composition of one embodiment may, as needed, contain other lubricating oil additives besides components (B) to (D) without impairing the effect of the present invention.

[0025] The following describes in detail the components contained in a lubricating oil composition according to one aspect of the present invention.

[0026] <Ingredient (A): Base Oil> The base oil (A) used in one embodiment of the present invention may be selected from one or more mineral oils and synthetic oils.

[0027] As mineral oils, examples include atmospheric residue obtained by atmospheric distillation of crude oils such as alkane-based crude oils, intermediate-based crude oils, and cycloalkane-based crude oils; distillate obtained by vacuum distillation of these atmospheric residues; and refined oil obtained by subjecting the distillate to one or more of the following refining processes: solvent deasphalting, solvent extraction, hydrogen cracking, solvent dewaxing, contact dewaxing, and hydrogen refining.

[0028] Examples of synthetic oils include, for instance, α-olefin homopolymers, α-olefin copolymers (e.g., ethylene-α-olefin copolymers with 8 to 14 carbon atoms), and polyα-olefins; isoparaffins; monoesters and diesters; ethers; alkylbenzenes; alkylnaphthalenes; synthetic oils obtained by isomerization of waxes produced from natural gas using the Fischer-Tropsch process (GTL waxes), and synthetic oils obtained by oligomerization of olefins produced from gaseous feedstocks (Ethylene to Liquid (ETL)). These synthetic oils are preferably manufactured from renewable resources.

[0029] In one embodiment of the present invention, the base oil (A) has a kinematic viscosity of 10.0 mm at 100°C. 2 / s or higher, 11.0mm 2 / s or higher or 12.0mm 2 / s or higher; additionally, there is no specific upper limit, for example, it can be 16.5mm. 2 / s or less, 15.5mm 2 / s or 15.0mm 2 / s or less.

[0030] In one embodiment of the present invention, the viscosity index of the base oil (A) used is preferably 90 or higher, more preferably 100 or higher, and even more preferably 110 or higher.

[0031] In this specification, kinematic viscosity means the value measured or calculated according to ASTM D445, and viscosity index means the value measured or calculated according to ASTM D2270.

[0032] It should be noted that the base oil (A) used in one embodiment of the present invention can be a single base oil or a mixture of two or more base oils. When using a mixture, the kinematic viscosity and viscosity index of the mixture are preferably within the ranges described above.

[0033] In one embodiment of the present invention, the content of base oil (A) based on the total amount (100% by mass) of the lubricating oil composition may be set to 60.00% by mass or more, 65.00% by mass or more, 70.00% by mass or more, 75.00% by mass or more, or 80.00% by mass or more. Alternatively, it may be set to 99.90% by mass or less, 99.50% by mass or less, 99.00% by mass or less, 97.00% by mass or less, 95.00% by mass or less, or 92.00% by mass or less.

[0034] <Ingredient (B): Calcium-based detergent> One embodiment of the present invention comprises a calcium-based detergent (B). The calcium-based detergent is an essential component for obtaining a lubricating oil composition with good demulsibility.

[0035] Examples of calcium-based detergents (B) used in one aspect of the present invention include calcium salicylate (B1), calcium sulfonate (B2), and calcium phenolate (B3). Among these, from the viewpoint of obtaining a lubricating oil composition with further improved demulsibility, calcium salicylate (B1) is preferred as the calcium-based detergent (B).

[0036] In one embodiment of the present invention, the content of calcium-based detergent (B) based on calcium atoms, on a total basis of the lubricating oil composition, may be set to, for example, 900 ppm or more by mass, 1100 ppm or more by mass, or 1200 ppm or more by mass, or 1600 ppm or less by mass.

[0037] In this specification, the calcium atom content means the value measured according to ASTM D5185.

[0038] In one embodiment of the present invention, the content of calcium-based detergent (B) in the lubricating oil composition is based on the total amount (100% by mass) of the lubricating oil composition. For example, it may be set to 0.10% by mass or more, 0.50% by mass or more, or 1.00% by mass or more. Alternatively, it may be set to 10.0% by mass or less, 8.00% by mass or less, or 6.00% by mass or less.

[0039] Calcium salicylate (B1) Calcium salicylate (B1) used as one embodiment of the present invention can be exemplified by compounds represented by the following general formula (b-1).

[0040] [Chemistry 4] In the above general formula (b-1), each R is an independent hydrocarbon group with 1 to 18 carbon atoms.

[0041] Alkyl groups with 1 to 18 carbon atoms can be listed as optional hydrocarbon groups for R.

[0042] The calcium salicylate (B1) used in one embodiment of the present invention can be superalkaline calcium salicylate (B11) with an alkalinity of more than 100 mg KOH / g, or neutral calcium salicylate (B12) with an alkalinity of less than 100 mg KOH / g, and they can be used in combination.

[0043] It should be noted that, in this instruction manual, the base value of calcium-based detergent (B) means the value measured by the perchloric acid method based on ASTM D2896.

[0044] In one embodiment of the present invention, the alkalinity of the superalkaline calcium salicylate (B11) used can be set to 120 mg KOH / g or more, 150 mg KOH / g or more, 170 mg KOH / g or more, or 200 mg KOH / g or more. Alternatively, it can be set to 400 mg KOH / g or less or 350 mg KOH / g or less.

[0045] In one embodiment of the present invention, the alkalinity of the neutral calcium salicylate (B12) used can be set to 0 mg KOH / g or more, 10 mg KOH / g or more, 20 mg KOH / g or more, 30 mg KOH / g or more, or 40 mg KOH / g or more, or it can be set to 70 mg KOH / g or less.

[0046] In one embodiment of the present invention, from the viewpoint of obtaining a lubricating oil composition with improved demulsibility, the content of superalkaline calcium salicylate (B11) can be set to 0.50% or more, 1.00% or more, or 1.50% or more based on the total amount (100% by mass) of the lubricating oil composition. Alternatively, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 10.0% or less, 5.00% or less, or 3.00% or less.

[0047] In one embodiment of the present invention, from the viewpoint of obtaining a lubricating oil composition with improved demulsibility, the content of neutral calcium salicylate (B12) based on the total amount (100% by mass) of the lubricating oil composition can be set to 1.00% by mass or more, 1.50% by mass or more, 3.00% by mass or more, or 5.00% by mass or more. Alternatively, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 10.0% by mass or less, 8.00% by mass or less, or 6.00% by mass or less.

[0048] It should be noted that when the content of EO units in the polyoxyalkylene glycol compound of component (C) exceeds 65 mol% relative to the total amount of EO units and PO units, a lubricating oil composition with excellent demulsibility can also be obtained by blending more than 5.0 wt% of neutral calcium salicylate (B12).

[0049] In one embodiment of the present invention, when alkaline calcium salicylate (B11) and neutral calcium salicylate (B12) are used in combination, the content of calcium salicylate (B1) can be set to 1.00% or more, 1.50% or more, or 2.00% or more based on the total amount (100% by mass) of the lubricating oil composition. Alternatively, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 10.0% or less, 8.00% or less, or 6.00% or less.

[0050] Calcium Sulfonate (B2) As one embodiment of the present invention, calcium sulfonate (B2) can be exemplified by compounds represented by the following general formula (b-2).

[0051] [Chemistry 5] In the above general formula (b-2), each R is an independent hydrocarbon group with 8 to 30 carbon atoms.

[0052] Examples of hydrocarbon groups that can be used as R include alkyl groups with 8 to 30 carbon atoms.

[0053] The calcium sulfonate (B2) used in one embodiment of the present invention can be a superalkaline calcium sulfonate (B21) with an alkalinity of 100 mg KOH / g or more, or a neutral calcium sulfonate (B22) with an alkalinity of less than 100 mg KOH / g, preferably a superalkaline calcium sulfonate (B21).

[0054] In one embodiment of the present invention, the alkalinity of the superalkaline calcium sulfonate (B21) used can be set to 150 mg KOH / g or more, 200 mg KOH / g or more, 225 mg KOH / g or more, or 300 mg KOH / g or more. Alternatively, it can be set to 400 mg KOH / g or less or 350 mg KOH / g or less.

[0055] In one embodiment of the present invention, from the viewpoint of obtaining a lubricating oil composition with improved demulsibility, the content of superalkaline calcium sulfonate (B21), based on the total amount (100% by mass) of the lubricating oil composition, can be set to 0.50% by mass or more, 0.80% by mass or more, or 1.00% by mass or more. In addition, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 10.0% by mass or less, 5.00% by mass or less, or 3.00% by mass or less.

[0056] Phenolic Calcium (B3) Calcium phenolate (B3) used in one aspect of the present invention can be exemplified by compounds represented by the following general formula (b-3).

[0057] [Chemistry 6] In the above general formula (b-3), R is independently a hydrocarbon group with 8 to 30 carbon atoms, and y is an integer greater than or equal to 0.

[0058] Examples of hydrocarbon groups that can be used as R include alkyl groups with 8 to 30 carbon atoms.

[0059] The calcium phenolate (B3) used in one embodiment of the present invention can be superalkaline calcium phenolate (B31) with an alkalinity of more than 100 mg KOH / g, or neutral calcium phenolate (B32) with an alkalinity of less than 100 mg KOH / g, preferably superalkaline calcium phenolate (B31).

[0060] In one embodiment of the present invention, the alkalinity of the superalkaline calcium phenolate (B31) used can be set to 150 mg KOH / g or more, 170 mg KOH / g or more, 200 mg KOH / g or more, or 220 mg KOH / g or more. Alternatively, it can be set to 400 mg KOH / g or less or 350 mg KOH / g or less.

[0061] In one embodiment of the present invention, from the viewpoint of obtaining a lubricating oil composition with improved demulsibility, the content of superalkaline calcium phenolate (B31) can be set to 0.50% or more, 0.80% or more, or 1.00% or more based on the total amount (100% by mass) of the lubricating oil composition. Alternatively, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 10.0% or less, 5.00% or less, or 3.00% or less.

[0062] One embodiment of the lubricating oil composition of the present invention may be substantially free of calcium sulfonate (B2) and calcium phenolate (B3). Specifically, the content of calcium sulfonate (B2) and calcium phenolate (B3) based on the total amount of the lubricating oil composition may be less than 0.01% by mass, less than 0.005% by mass, or less than 0.001% by mass.

[0063] One embodiment of the lubricating oil composition of the present invention may contain a metal-based detergent other than the calcium-based detergent (B) described above, or it may not contain one. Examples of such metal-based detergents include, for instance, magnesium-based detergents.

[0064] In one embodiment of the present invention, the content of metal detergents other than calcium detergent (B) in the lubricating oil composition may be set to less than 0.01% by mass, less than 0.005% by mass, or less than 0.001% by mass based on the total amount of the lubricating oil composition.

[0065] <Ingredient (C): Polyoxyalkylene glycol compound> One embodiment of the present invention provides a lubricating oil composition comprising a polyoxyalkylene glycol compound (C) of the following general formula (1). In this polyoxyalkylene glycol compound (C), the content of EO units is 65 mol% or less relative to the total amount of EO units and PO units. If the content of EO units exceeds 65 mol% relative to the total amount of EO units and PO units, there is a concern that a lubricating oil composition with excellent demulsibility may not be obtained. As described above, if water generated in a hydrogen fuel cell engine mixes into the lubricating oil composition, the lubricating oil composition may sometimes emulsify, making it difficult to remove the water. In the present invention, by incorporating a polyoxyalkylene glycol compound (C) having a specific structure into the lubricating oil composition as an demulsifier, excellent demulsibility can be imparted to the lubricating oil composition.

[0066] [Chemistry 7] In the aforementioned general formula (1), E represents ethylene and P represents propylene. a and c are each independently a number of 0 or more. b is a number of 1 or more. Here, E is preferably -CH2CH2- and P is preferably -CH2CH(CH3)-. In addition, the polyoxyalkylene glycol compound (C) is a block copolymer formed by block bonding of EO units and PO units.

[0067] It should be noted that the content of EO units relative to the total amount of EO units and PO units can be 0 mol%. From the viewpoint of suppressing turbidity of the lubricating oil composition and achieving a good appearance, the content of EO units relative to the total amount of EO units and PO units is preferably more than 0 mol.

[0068] In one embodiment of the present invention, the number-average molecular weight of the polyoxyalkylene glycol compound (C) used can exceed 4,000. If the number-average molecular weight of the polyoxyalkylene glycol compound (C) is below 4,000, there is a concern that a lubricating oil composition with excellent demulsibility may not be obtained.

[0069] From the viewpoint of further improving the demulsibility of the lubricating oil composition, the number average molecular weight of the polyoxyalkylene glycol compound (C) is preferably 4,500 or more, more preferably 5,000 or more, and even more preferably 5,300 or more.

[0070] Furthermore, from the viewpoint of solubility in base oil and to suppress turbidity in the lubricating oil composition to achieve a good appearance, the number average molecular weight of the polyoxyalkylene glycol compound (C) is preferably 10,000 or less, more preferably 9,500 or less, and even more preferably 9,000 or less.

[0071] It should be noted that, in this specification, number-average molecular weight means the number-average molecular weight converted to polystyrene, measured by the methods described in the examples below.

[0072] Furthermore, from the viewpoint of further improving the demulsibility of the lubricating oil composition, the weight-average molecular weight of the polyoxyalkylene glycol compound (C) is preferably more than 5,000, more preferably more than 5,500, and even more preferably more than 6,000.

[0073] Furthermore, from the viewpoint of solubility in base oil and to suppress turbidity of the lubricating oil composition to achieve a good appearance, a concentration of 12,000 or less is preferred, 11,500 or less is more preferred, and 11,000 or less is even more preferred.

[0074] It should be noted that, in this specification, weight-average molecular weight means the weight-average molecular weight converted to polystyrene, measured by the method described in the examples below.

[0075] In one aspect of the present invention, from the viewpoint of suppressing turbidity of the lubricating oil composition to achieve a good appearance and further improving the demulsibility of the lubricating oil composition, the content of EO units in the polyoxyalkylene glycol compound (C) is preferably more than 0 mol% and less than 65 mol% relative to the total amount of EO units and PO units, more preferably 1 to 50 mol%, further preferably 10 to 30 mol%, and even more preferably 15 to 25 mol%.

[0076] In the above general formula (1), a and c are each independently a number greater than or equal to 0. That is, a and c can both be 0 or only one of them can be 0. From the viewpoint of suppressing the turbidity of the lubricating oil composition and making it look good, a+c is preferably a number greater than or equal to 1.

[0077] Furthermore, from the viewpoints of further improving the demulsibility of the lubricating oil composition, its solubility in the base oil, and suppressing turbidity of the lubricating oil composition to achieve a good appearance, a and c are each preferably in the number of 4 to 27, more preferably in the number of 10 to 25, and even more preferably in the number of 12 to 24.

[0078] In the above general formula (1), b is a number greater than or equal to 1.

[0079] From the viewpoints of further improving the demulsibility of the lubricating oil composition, its solubility in the base oil, and suppressing turbidity of the lubricating oil composition to achieve a good appearance, b is preferably a number of 64 to 129, more preferably a number of 66 to 125, even more preferably a number of 67 to 120, and even more preferably a number of 70 to 116.

[0080] It should be noted that the polyoxyalkylene glycol compound (C) can be appropriately manufactured by, for example, a known method of polymerizing oxypropylene with propylene glycol as an initiator in the presence of a catalyst such as potassium hydroxide, followed by polymerization of oxyethylene. The manufacturing method is not particularly limited.

[0081] In one aspect of the present invention, from the viewpoint of further improving the demulsibility of the lubricating oil composition, the content of the polyoxyalkylene glycol compound (C) is preferably 0.001% to 0.50% by mass, more preferably 0.005% to 0.30% by mass, and even more preferably 0.01% to 0.10% by mass, based on the total amount (100% by mass) of the lubricating oil composition.

[0082] In one aspect of the present invention, from the viewpoint of obtaining a lubricating oil composition with improved demulsibility, the content ratio of the calcium-based detergent in component (B) to the polyoxyalkylene glycol compound in component (C) [component (C) / component (B)] can be set to 0.15 or less, 0.10 or less, or 0.08 or less by mass. In addition, the lower limit value is not particularly limited, and for example, it can be set to 0.0001 or more, 0.001 or more, or 0.005 or more.

[0083] <Ingredient (D): Imide compound> In one embodiment of the present invention, the lubricating oil composition contains at least one imide compound (D) selected from compounds represented by the following general formulas (2) and (3) in an amount of 1.50% by mass or more. If the content of the imide compound (D) is less than 1.50% by mass, there is a concern that a lubricating oil composition with excellent demulsibility may not be obtained.

[0084] The imide compound (D), as shown in the following general formulas (2) and (3), has -R B -NH- or -R B1 The structure obtained by bonding nitrogen atoms and hydrogen atoms in the -NH- structural unit is called a "non-capped" structure. In this invention, by blending this imide compound (D) with a specific structure as a dispersant together with the aforementioned polyoxyalkylene glycol compound (C) into the lubricating oil composition, it is possible to impart excellent emulsification resistance to the lubricating oil composition.

[0085] [Chemistry 8] In the aforementioned general formulas (2) and (3), R A R A1 and R A2 Each is an alkenyl group with a weight-average molecular weight of 500–4,000. R B R B1 and R B2 Each is an alkylene group having 2 to 5 carbon atoms. X1 and X2 are each an integer from 1 to 10.

[0086] As an optional R A R A1 and RA2 The alkenyl group can be exemplified by, for example, polybutene-based, polyisobutylene-based, ethylene-propylene copolymer, etc. Among these, polybutene-based and polyisobutylene-based are preferred, and polyisobutylene-based is more preferred.

[0087] The weight-average molecular weight of the above-mentioned alkenyl group is 500-4,000, preferably 900-3,000, more preferably 1,300-2,800, and even more preferably 1,800-2,600.

[0088] As an optional R B R B1 and R B2 Alkylenes, for example, include methylene, ethylene, trimethylene, various butylenes, various pentylenes, etc. It should be noted that in this specification, "various" in various butylenes, etc., means including linear, branched, and their isomers.

[0089] x1 is an integer from 1 to 10, preferably an integer from 2 to 5, and more preferably 3 or 4.

[0090] x2 is an integer from 1 to 10, preferably an integer from 3 to 7, and more preferably 5 or 6.

[0091] In addition, the monoimide compound (D1) shown in general formula (2) and the diimide compound (D2) shown in general formula (3) can be boron modified or not, and they can be used in combination.

[0092] In one aspect of the present invention, the content of the imide compound (D) based on nitrogen atom conversion, from the viewpoint of obtaining a lubricating oil composition with further improved demulsibility, can be set to 0.08% by mass or more, 0.09% by mass or more, 0.10% by mass or more, or 0.12% by mass or more based on the total amount (100% by mass) of the lubricating oil composition. Alternatively, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 0.155% by mass or less, 0.15% by mass or less, 0.145% by mass or less, or 0.14% by mass or less.

[0093] In another aspect of the present invention, from the viewpoint of obtaining a lubricating oil composition with further improved demulsibility, the content of imide compound (D), based on the total amount (100% by mass) of the lubricating oil composition, can be set to 2.00% by mass or more, 3.00% by mass or more, or 4.00% by mass or more. In addition, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 10.0% by mass or less, 9.00% by mass or less, or 8.00% by mass or less.

[0094] In one aspect of the present invention, from the viewpoint of obtaining a lubricating oil composition with improved demulsibility, the content ratio of the polyoxyalkylene glycol compound of component (C) to the imide compound of component (D) [component (C) / component (D)] can be set to 0.10 or less, 0.05 or less, or 0.03 or less by mass. The lower limit value is not particularly limited, but can be set to 0.0001 or more, 0.001 or more, or 0.005 or more.

[0095] <Ingredient (E): Imidamine compound> In one embodiment of the present invention, a lubricating oil composition may further contain, in addition to containing one or more imide compounds (D) selected from the compounds shown in general formulas (2) and (3) above, one or more imide compounds (E) selected from the compounds shown in general formulas (4) and (5) below. The imide compound (E) has -R in the non-capped imide compound (D). B -NH- or -R B1 In the structural unit shown by -NH-, the hydrogen atom is replaced by R. C The resulting structure is called a "cap-type".

[0096] [Chemistry 9] In the aforementioned general formulas (4) and (5), R A R A1 and R A2 Each is an alkenyl group with a weight-average molecular weight of 500–4,000. R B R B1 and R B2 Each is an alkylene group having 2 to 5 carbon atoms. R C It is an alkyl group with 1 to 10 carbon atoms or a group represented by -(AO)nH (where A represents an alkylene group with 2 to 4 carbon atoms, and n represents an integer from 1 to 10). X1 and X2 are each independently an integer from 1 to 10.

[0097] As an optional R A R A1 and R A2 The alkenyl group can be exemplified by, for example, polybutene-based, polyisobutylene-based, ethylene-propylene copolymer, etc. Among these, polybutene-based and polyisobutylene-based are preferred, and polyisobutylene-based is more preferred.

[0098] The weight-average molecular weight of the above-mentioned alkenyl group is 500-4,000, preferably 900-3,000, more preferably 1,300-2,800, and even more preferably 1,800-2,600.

[0099] As an optional R B RB1 and R B2 Alkylenes, for example, include methylene, ethylene, trimethylene, various butylenes, various pentylenes, etc. It should be noted that in this specification, "various" in various butylenes, etc., means including linear, branched, and their isomers.

[0100] R C It is an alkyl group with 1 to 10 carbon atoms or a group represented by -(AO)nH (where A represents an alkylene group with 2 to 4 carbon atoms, and n represents an integer from 1 to 10).

[0101] Examples of the aforementioned alkyl groups include straight-chain or branched alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 1,1-dimethylhexyl, 2-ethylhexyl, nonyl, 1,1-dimethylheptyl, and decyl.

[0102] Examples of alkylene groups with 2 to 4 carbon atoms as shown in A include ethylene, trimethylene, and various butylene groups, with ethylene being the most preferred.

[0103] n is an integer from 1 to 10, preferably an integer from 1 to 5, and more preferably an integer from 1 to 3.

[0104] x1 is an integer from 1 to 10, preferably an integer from 2 to 5, and more preferably 3 or 4.

[0105] x2 is an integer from 1 to 10, preferably an integer from 3 to 7, and more preferably 5 or 6.

[0106] In addition, the monoimide compound (E1) shown in general formula (4) and the diimide compound (E2) shown in general formula (5) can be boron modified or not, and they can be used in combination.

[0107] In one aspect of the present invention, the content of the imide compound (E) based on nitrogen atom conversion, from the viewpoint of obtaining a lubricating oil composition with further improved demulsibility, can be set to 0.05% by mass or more, 0.07% by mass or more, 0.08% by mass or more, or 0.09% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition. Alternatively, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 0.13% by mass or less, 0.12% by mass or less, 0.11% by mass or less, or 0.10% by mass or less.

[0108] In another aspect of the present invention, from the viewpoint of obtaining a lubricating oil composition with further improved demulsibility, the content of the imide compound (E), based on the total amount (100% by mass) of the lubricating oil composition, can be set to 0.10% by mass or more, 0.50% by mass or more, 1.00% by mass or more, or 1.50% by mass or more. In addition, from the viewpoint of obtaining a lubricating oil composition with good lubricity, it can be set to 5.00% by mass or less, 4.00% by mass or less, or 3.00% by mass or less.

[0109] In one aspect of the present invention, from the viewpoint of obtaining a lubricating oil composition with improved demulsibility, the content ratio of the imide compound of component (D) to the imide compound of component (E) [component (D) / component (E)] can be set to 10.0 or less, 7.00 or less, or 5.00 or less by mass, and the lower limit is not particularly limited, for example, it can be set to 0.10 or more, 0.50 or more, or 1.00 or more.

[0110] <Additives for Lubricating Oils> In one embodiment of the present invention, the lubricating oil composition may, as needed, contain other lubricating oil additives besides components (B) to (D), without impairing the effects of the present invention.

[0111] Examples of additives for such lubricants include viscosity index improvers, pour point depressants, antioxidants, wear-resistant agents or extreme pressure agents, friction modifiers, metal inertizers, defoamers, and demulsifiers other than component (C).

[0112] These lubricant additives can be used individually or in combination of two or more.

[0113] [Viscosity index improver] The lubricating oil composition of one embodiment of the present invention may further contain a viscosity index improver. The viscosity index improver may be used alone or in combination of two or more.

[0114] As a viscosity index improver used in one aspect of the present invention, examples include non-dispersed polymethyl methacrylate, dispersed polymethyl methacrylate, olefin copolymers (e.g., ethylene-propylene copolymers), dispersed olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers).

[0115] [Pour point depressant] The lubricating oil composition of one embodiment of the present invention may further contain a pour point depressant. The pour point depressant may be used alone or in combination of two or more types.

[0116] Examples of pour point depressants used in one aspect of the present invention include polymethacrylates, alkylated aromatic compounds, copolymers of fumarate and vinyl acetate, and copolymers of ethylene and vinyl acetate, with polymethacrylates having a weight-average molecular weight of 40,000 to 200,000 being preferred.

[0117] [Antioxidants] The lubricating oil composition of one aspect of the present invention may further contain an antioxidant. The antioxidant may be used alone or in combination of two or more.

[0118] Examples of antioxidants used in one aspect of the present invention include, for example, amine-based antioxidants and phenolic antioxidants. Examples of amine-based antioxidants include, for example, alkylated diphenylamines having alkyl groups having 3 to 20 carbon atoms, and other diphenylamine-based antioxidants. Examples of phenolic antioxidants include, for example, 2,6-di-tert-butylphenol, 4,4'-methylenebis(2,6-di-tert-butylphenol), isooctyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0119] [Abrasion resistant agent or extreme pressure agent] The lubricating oil composition of one embodiment of the present invention may further contain a wear-resistant agent or an extreme pressure agent. The wear-resistant agent or extreme pressure agent may be used alone or in combination of two or more.

[0120] Examples of wear-resistant agents or extreme pressure agents include sulfur-containing compounds such as zinc dialkyl dithiophosphate (ZnDTP), zinc phosphate, zinc dithiocarbamate, disulfide compounds, sulfurized olefins, sulfurized oils, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfide compounds; phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and their amine or metal salts; and sulfur- and phosphorus-containing wear-resistant agents such as thiophosphites, thiophosphates, thiophosphonates, and their amine or metal salts.

[0121] Among these, zinc dialkyl dithiophosphate (ZnDTP) is preferred.

[0122] Friction modifier The lubricating oil composition of one aspect of the present invention may further contain a friction modifier. The friction modifier may be used alone or in combination of two or more.

[0123] Examples of friction modifiers used in one aspect of the present invention include molybdenum-based friction modifiers such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdate; and ashless friction modifiers such as aliphatic amines, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, and aliphatic ethers having at least one alkyl or alkenyl group with 6 to 30 carbon atoms in the molecule.

[0124] [Metal inert agent] The lubricating oil composition of one embodiment of the present invention may further contain a metal inert agent. The metal inert agent may be used alone or in combination of two or more.

[0125] Examples of metal inert agents used in one aspect of the present invention include benzotriazole, benzotriazole derivatives, and thiadiazole derivatives.

[0126] [Defoamer] The lubricating oil composition of one aspect of the present invention may further contain an antifoaming agent. The antifoaming agent may be used alone or in combination of two or more.

[0127] Examples of defoamers used in one aspect of the present invention include alkyl silicone defoamers, fluorosilicone defoamers, and fluoroalkyl ether defoamers.

[0128] [Demulsifier] The lubricating oil composition of one aspect of the present invention may further contain an antiemulsifier in addition to component (C).

[0129] Examples of demulsifiers used in one aspect of this invention include polyoxyethylene polyalkylene alkyl ethers. They can be used alone or in combination of two or more.

[0130] [Method for manufacturing lubricating oil composition] The method for manufacturing the lubricating oil composition, as one aspect of the present invention, is not particularly limited, but is preferably a method that includes a step of blending various other additives into the base oil (A) as needed. The blending order of the components can be appropriately set.

[0131] [Properties of the lubricating oil composition] One embodiment of the lubricating oil composition of the present invention has a kinematic viscosity of 10.0 mm at 100°C. 2 / s or higher, 11.0mm 2 / s or higher, 12.0mm 2 / s or higher; additionally, there is no specific upper limit, for example, it can be 16.5mm. 2 / s or less, 15.5mm 2 / s or less or 15.0mm 2 / s or less.

[0132] The alkalinity (perchloric acid method) of the lubricating oil composition of one aspect of the present invention is not particularly limited, and can be set to 4.0 mg KOH / g or more or 5.0 mg KOH / g or more, or 8.0 mg KOH / g or less or 9.0 mg KOH / g or less.

[0133] [Uses of Lubricating Oil Compositions] One embodiment of the lubricating oil composition of the present invention exhibits excellent demulsification properties and good water separation properties. Therefore, this lubricating oil composition can easily expel water and prevent deterioration of its lubricity.

[0134] The lubricating oil composition of one aspect of the present invention can be applied to various devices capable of exhibiting the above-mentioned properties, and can be suitably used for lubrication between components in an internal combustion engine. Furthermore, it is particularly suitable for lubrication between components in an internal combustion engine that operates using hydrogen fuel.

[0135] Furthermore, considering the above-mentioned characteristics of the lubricating oil composition of one aspect of the present invention, the present invention may also provide the following [I].

[0136] [I] A lubrication method for an internal combustion engine, wherein the lubricating oil composition of one aspect of the present invention described above is applied to the lubrication of a hydrogen fuel cell engine. Example

[0137] The invention will now be described in more detail through examples, but the invention is not limited to these examples at all. It should be noted that the methods for measuring various physical properties are as follows.

[0138] (1) Kinematic viscosity The determination was performed according to ASTM D445.

[0139] (2) Viscosity index Calculations were performed according to ASTM D2270.

[0140] (3) Alkalinity (perchloric acid method) The determination was performed using the perchloric acid method according to ASTM D2896.

[0141] (4) Calcium atom (Ca) content The determination was performed according to ASTM D5185.

[0142] (5) Number-average molecular weight (Mn), weight-average molecular weight (Mw) The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of polyoxyalkylene glycol compounds and imide compounds were determined using gel permeation chromatography (GPC) under the following conditions and converted to standard polystyrene.

[0143] (Measurement conditions) • Column: KF-G (protective column) ×1 + KF·402.5HQ ×2 • Developing solvent: chloroform • Flow rate: 0.3 mL / min.

[0144] Examples 1-9, Comparative Examples 1-12, Reference Example 1 The components shown in Tables 1 and 2 were added at the same mixing amounts as in the tables and thoroughly mixed to prepare lubricating oil compositions. The base oils and various additives used in the examples and comparative examples are shown below.

[0145] <Ingredient (A): Base Oil> • "Base oil": Mineral oil classified as Group II of API base oils, with a kinematic viscosity of 90.51 mmHg at 40°C. 2 / s, kinematic viscosity at 100℃ = 10.89mm 2 / s, viscosity index = 107.

[0146] <Ingredient (B): Calcium-based detergent> • "Calcium salicylate (1)": Alkali value (perchloric acid method) = 225 mg KOH / g calcium salicylate, Ca content = 8.0% by mass. • "Calcium salicylate (2)": Alkali value (perchloric acid method) = 226 mg KOH / g calcium salicylate, Ca content = 7.9% by mass. • "Calcium salicylate (3)": Alkali value (perchloric acid method) = 64 mg KOH / g calcium salicylate, Ca content = 2.9% by mass. • "Calcium sulfonate (1)": Alkali value (perchloric acid method) = 300 mg KOH / g of calcium sulfonate, Ca content = 11.6% by mass • "Calcium sulfonate (2)": Alkali value (perchloric acid method) = 307 mg KOH / g of calcium sulfonate, Ca content = 11.9% by mass • "Calcium Phenol": Calcium phenol with an alkalinity (perchloric acid method) of 250 mg KOH / g and a Ca content of 9.25% by mass.

[0147] <Ingredient (C): Polyoxyalkylene glycol compound (PAG compound)> ·PAG compound (1): Polyoxyethylene polyoxypropylene glycol formed by block bonding of EO units and PO units (number average molecular weight = 8,500, content of EO units relative to the total amount of EO units and PO units = 23 mol%). ·PAG compound (2): Polyoxyethylene polyoxypropylene glycol formed by block bonding of EO units and PO units (number average molecular weight = 5,700, content of EO units relative to the total amount of EO units and PO units = 29 mol%).

[0148] ·PAG compound (3): Polyoxyethylene polyoxypropylene glycol formed by block bonding of EO units and PO units (number average molecular weight = 1,900, content of EO units relative to the total amount of EO units and PO units = 71 mol%). ·PAG compound (4): Polyoxyethylene polyoxypropylene glycol formed by random bonding of EO units and PO units (number average molecular weight = 980, content of EO units relative to the total amount of EO units and PO units = 70 mol%). ·PAG compound (5): Polyoxyethylene polyoxypropylene glycol formed by random bonding of EO units and PO units (number average molecular weight = 1360, content of EO units relative to the total amount of EO units and PO units = 90 mol%). ·PAG compound (6): Polyoxyethylene polyoxypropylene glycol formed by random bonding of EO units and PO units (number average molecular weight = 1600, content of EO units relative to the total amount of EO units and PO units = 90 mol%).

[0149] <Ingredient (D): Imide compound> • Non-capped imide compound (1): Non-boron modified polybutene succinic acid bisimide with a non-capped structure (N content = 1.08% by mass, R in the above general formula (3) A1 and R A2 Polybutene-based, R B1 and R B2 (It is an ethylidene imide compound). • Non-capped imide compound (2): Non-boron modified polybutene succinic acid bisimide with a non-capped structure (N content = 2.1% by mass, R in the above general formula (3)) A1 and R A2 Polybutene-based, R B1 and R B2 (It is an ethylidene imide compound).

[0150] <Ingredient (E): Imidamine compound> • Cap-type imide compound (1): Non-boron modified polybutene succinic acid bisimide with a cap-type structure (N content = 1.0% by mass, R in the above general formula (5) A1 and R A2 Polybutene-based, R B1 and R B2 Ethylene, R C (An imide compound with the group shown as -(C2H4O)2-H). • Cap-type imide compound (2): Boron-modified polybutene succinic acid diimide with a cap-type structure (N content = 1.23% by mass, R in the above general formula (5) A1 and R A2 Polybutene-based, R B1 and R B2 Ethylene, R C It is an imide compound with a boric acid group (a group obtained by modifying the group shown in -(C2H4O)2-H with boric acid). Other additives include antioxidants, wear-resistant agents (ZnDTP), metal inerts, pour point depressants, and defoamers.

[0151] The prepared lubricating oil composition was subjected to the following water resistance tests. The test results are shown in Tables 1 and 2.

[0152] [Water Resistance Test] Using the prepared lubricating oil composition as the sample, according to ASTM D 2619 "Standard Test Method for Hydrolytic Stability of Hydraulic Fluids (Beverage Bottle Method)," a copper catalyst and 25 mL of distilled water were added to a container containing 75 mL of the sample. The temperature was raised to 93°C, and the container was kept at this temperature while rotating for 48 hours. Afterward, the mixture was cooled to room temperature (25°C), and the liquid in the container was transferred to a graduated cylinder and allowed to stand for 24 hours. The separation of the oil layer, water layer, and emulsion layer after standing was visually evaluated in the following four stages. Samples with evaluation results of A and B were considered acceptable.

[0153] A: The oil layer and water layer are completely separated; the water layer is not turbid. B: The oil layer and water layer are completely separated; the water layer is slightly turbid. C: Separated into two layers: an oil layer and an emulsion layer. D: It does not separate into oil and water layers, but forms an emulsion layer.

[0154] [Table 1] .

[0155] [Table 2] .

[0156] According to Tables 1 and 2, the lubricating oil compositions of Examples 1-9, containing a calcium-based detergent (B), a polyoxyalkylene glycol compound (C) with a specific structure, and a specified amount of an imide compound (D) with a specific structure, showed good results in water resistance tests and excellent demulsibility. In particular, the water resistance test results of Examples 1-6, which used calcium salicylate (B1) as the calcium-based detergent (B), were extremely good. The lubricating oil compositions of Examples 7-9, which used calcium sulfonate (B2) or calcium phenolate (B3) as the calcium-based detergent (B), showed generally acceptable results, but their demulsibility was worse than that of Examples 1-6.

[0157] On the other hand, in the lubricating oil compositions of Comparative Examples 1 to 12, as a result of the water resistance test, emulsions were formed, and the demulsification properties were poor compared with those of Examples 1 to 9.

[0158] It should be noted that, as shown in Reference Example 1, even when the content of EO units in the polyoxyalkylene glycol compound of component (C) exceeds 65 mol% relative to the total amount of EO units and PO units, a lubricating oil composition with excellent demulsibility can be obtained by blending more than 5.0 wt% of neutral calcium salicylate (B12).

Claims

1. A lubricating oil composition for use in an internal combustion engine operating on hydrogen fuel. The lubricating oil composition contains: a base oil (A), a calcium-based detergent (B), a polyoxyalkylene glycol compound (C) of general formula (1) below, and one or more imide compounds (D) selected from compounds of general formulas (2) and (3) below. In the polyoxyalkylene glycol compound (C), the content of EO units relative to the total amount of EO units and PO units is less than 65 mol%. The content of imide compound (D) is 1.50% by mass or more. [Chemistry 1] In the general formula (1), E represents ethylene, P represents propylene, a and c are each independently numbers greater than or equal to 0, and b is a number greater than or equal to 1. [Chemistry 2] In the general formulas (2) and (3), R A R A1 and R A2 Each is an alkenyl group with a weight-average molecular weight of 500-4000, R B R B1 and R B2 Each is an alkylene group having 2 to 5 carbon atoms, and X1 and X2 are each an integer from 1 to 10.

2. The lubricating oil composition according to claim 1, wherein, Calcium-based detergents (B) contain calcium salicylate (B1).

3. The lubricating oil composition according to claim 1 or 2, wherein, Calcium-based detergents (B) are essentially free of calcium sulfonate (B2) and calcium phenolate (B3).

4. The lubricating oil composition according to any one of claims 1 to 3, wherein, The content of calcium-based detergent (B) is 0.10~10.0% by mass.

5. The lubricating oil composition according to any one of claims 1 to 4, wherein, The content of polyoxyalkylene glycol compound (C) is 0.001% to 0.1% by mass.

6. The lubricating oil composition according to any one of claims 1 to 5, wherein, The content of imide compound (D) is less than 10.0% by mass.

7. The lubricating oil composition according to any one of claims 1 to 6, further comprising one or more imide compounds (E) selected from the compounds shown in the following general formulas (4) and (5). [Chemistry 3] In the general formulas (4) and (5), R A R A1 and R A2 Each is an alkenyl group with a weight-average molecular weight of 500-4000, R B R B1 and R B2 Each is independently an alkylene group having 2 to 5 carbon atoms, R C It is an alkyl group with 1 to 10 carbon atoms or a group represented by -(AO)nH, where X1 and X2 are each independently an integer from 1 to 10. In the formula -(AO)nH, A represents an alkylene group with 2 to 4 carbon atoms, and n represents an integer from 1 to 10.

8. The lubricating oil composition according to any one of claims 1 to 7, wherein, The content ratio of calcium-based detergent (B) to polyoxyalkylene glycol compound (C) [component (C) / component (B)] is 0.15 or less by mass.

9. The lubricating oil composition according to any one of claims 1 to 8, wherein, The content ratio of polyoxyalkylene glycol compound (C) to imide compound (D) [component (C) / component (D)] is 0.10 or less by mass.

10. The lubricating oil composition according to any one of claims 1 to 9, wherein, The content ratio of imide compound (D) to imide compound (E) [component (D) / component (E)] is 10.0 or less by mass.

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