Lubricating oil composition

Abstract

A lubricating oil composition containing a base oil (A) containing an ester oil (A1), a phenothiazine-based compound (B), and a non-metal thiophosphate-based compound (C) is prepared. The ester oil (A1) preferably contains a diester oil (A11).

Description

Technical Field

[0001] The present invention relates to a lubricating oil composition. Background Art

[0002] In recent years, as bearings assembled in devices such as automotive electrical equipment, home appliances, and OA office equipment, oil-impregnated bearings obtained by sintering and molding metal powders have been widely used.

[0003] An oil-impregnated bearing is generally manufactured by forming a porous metal body through various processes such as mixing, molding, sintering, and sizing of metal powder as a raw material, and then using an impregnation device to vacuum-impregnate the metal body with lubricating oil. It is a sliding bearing used in a self-lubricating state.

[0004] The oil-impregnated bearing supplies the lubricating oil composition impregnated into the porous metal body to the sliding surface between the rotating shaft and the inner surface of the bearing by the pumping action caused by the rotation of the rotating shaft for lubrication. It not only has excellent durability and rigidity but also has the advantage that the production cost is also suppressed to a low level.

[0005] As the base oil of the lubricating oil composition impregnated into the oil-impregnated bearing, various base oils such as mineral oil, hydrocarbon-based synthetic oil, ether oil, ester oil, fluorinated oil, and silicone oil are used, for example. Patent Document 1 proposes a lubricating oil composition for an oil-impregnated bearing using ester oil as the base oil (for example, refer to Patent Document 1).

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-210443 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, oil-impregnated bearings are usually used without oil supply. Therefore, if the amount of the lubricating oil composition impregnated into the oil-impregnated bearing easily decreases over time, the life of the oil-impregnated bearing is likely to be reduced.

[0011] Therefore, the present inventors have repeatedly conducted in-depth research on its formulation in order to create a lubricating oil composition for an oil-impregnated bearing that is less likely to evaporate. As a result, a formulation has been found that can make the lubricating oil composition for an oil-impregnated bearing using ester oil as the base oil less likely to evaporate, has excellent evaporation characteristics, and can also make the abrasion resistance excellent.

[0012] It should be noted that the lubricating oil composition having excellent evaporation characteristics and abrasion resistance is not limited to the use in oil-impregnated bearings and can meet the requirements in various uses.

[0013] The object of the present invention is to provide a lubricating oil composition having excellent evaporation characteristics and abrasion resistance.

[0014] Means for Solving the Problem

[0015] According to the present invention, the following [1] to [5] are provided.

[0016] [1] A lubricating oil composition containing: a base oil (A) containing an ester oil (A1), a phenothiazine compound (B), and a non-metallic thiophosphate compound (C).

[0017] [2] The lubricating oil composition according to the above [1], which is used as an impregnating bearing oil.

[0018] [3] A method for using the aforementioned lubricating oil composition, wherein the lubricating oil composition according to the above [1] is used as an impregnating bearing oil.

[0019] [4] An oil-impregnated bearing impregnated with the lubricating oil composition according to the above [1].

[0020] [5] A method for manufacturing a lubricating oil composition, which includes a step of mixing a base oil (A) containing an ester oil (A1), a phenothiazine compound (B), and a non-metallic thiophosphate compound (C).

[0021] Effect of the Invention

[0022] According to the present invention, a lubricating oil composition having excellent evaporation characteristics and abrasion resistance can be provided. Detailed Description of the Invention

[0023] The upper limit value and the lower limit value of the numerical range described in this specification can be arbitrarily combined. For example, when "A to B" and "C to D" are described as numerical ranges, the numerical ranges of "A to D" and "C to B" also fall within the scope of the present invention.

[0024] In addition, the numerical range "lower limit value to upper limit value" described in this specification means above the lower limit value and below the upper limit value unless otherwise specified.

[0025] In addition, in this specification, the numerical values in the examples are values that can be used as the upper limit value or the lower limit value.

[0026] [Regarding the Lubricating Oil Composition]

[0027] The lubricating oil composition of the present embodiment contains: a base oil (A) containing an ester oil (A1), a phenothiazine compound (B), and a non-metallic thiophosphate compound (C).

[0028] The inventors of the present invention have repeatedly conducted in-depth research to solve the above problems.

[0029] As a result, the present inventors obtained a new insight that phenothiazine-based compounds have the effect of inhibiting the evaporation of ester oil.

[0030] Based on this insight, the present inventors further repeatedly conducted in-depth research, and as a result, it was found that by using a non-metal thiophosphate-based compound, it is possible to impart abrasion resistance to the lubricating oil composition without impairing the effect of inhibiting the evaporation of ester oil by the phenothiazine-based compound.

[0031] Based on these insights, the present inventors further repeatedly conducted various studies, and thus completed the present invention.

[0032] It should be noted that in the following description, "base oil (A)", "phenothiazine-based compound (B)", and "non-metal thiophosphate-based compound (C)" will also be referred to as "component (A)", "component (B)", and "component (C)", respectively.

[0033] The lubricating oil composition of the present embodiment may be composed only of component (A), component (B), and component (C), and may further contain other components in addition to component (A), component (B), and component (C).

[0034] In the lubricating oil composition of the present embodiment, the total content of component (A), component (B), and component (C) is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, still further preferably 75% by mass or more, and even further preferably 80% by mass or more based on the total amount of the lubricating oil composition.

[0035] Hereinafter, each component contained in the lubricating oil composition of the present embodiment will be described in detail.

[0036] <Base oil (A)>

[0037] The lubricating oil composition of the present embodiment contains: a base oil (A) containing an ester oil (A1).

[0038] Since the lubricating oil composition of the present embodiment contains a phenothiazine-based compound (B), the evaporation characteristics of the ester oil (A1) are improved, and the evaporation characteristics of the lubricating oil composition can be made excellent.

[0039] Here, from the viewpoint of more easily enjoying the effects of the present invention, the content of the ester oil (A1) in the base oil (A) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, further preferably 70% by mass to 100% by mass, still further preferably 80% by mass to 100% by mass, even further preferably 90% by mass to 100% by mass, and yet further preferably 95% by mass to 100% by mass based on the total amount of the base oil (A).

[0040] It should be noted that the kinematic viscosity of the base oil (A) at 100 °C is preferably 2.0 mm 2 / s to 30.0 mm 2 / s, more preferably 2.5 mm 2 / s to 25.0 mm 2 / s, and even more preferably 3.0 mm 2 / s to 22.0 mm 2 / s.

[0041] In addition, the viscosity index of the base oil (A) is preferably 65 or more.

[0042] When using a mixed oil obtained by combining two or more base oils as the base oil (A), the kinematic viscosity and viscosity index of the mixed oil are preferably in the above ranges.

[0043] It should be noted that the kinematic viscosity and viscosity index of the base oil (A) are values measured and calculated in accordance with JIS K2283:2000.

[0044] In the lubricating oil composition of the present embodiment, the content of the base oil (A) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, still more preferably 80% by mass or more, based on the total amount of the lubricating oil composition. In addition, it is preferably 99.5% by mass or less, more preferably 99.0% by mass or less, and even more preferably 98.0% by mass or less.

[0045] (Ester oil (A1))

[0046] As the ester oil (A1), compounds having an ester bond can be cited.

[0047] Specific examples include diester oil (A11), polyol ester oil (A12), and aromatic ester oil (A13).

[0048] The ester oil (A1) can be used alone or in combination of two or more.

[0049] -Diester oil (A11)-

[0050] The diester oil (A11) is an ester of a dibasic acid and an alcohol, and is preferably a compound represented by the following general formula (a-1).

[0051] [Chemical formula 1]

[0052]

[0053] In the above general formula (a-1), R a1 and R a2Each independently represents an alkyl group having 2 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. Further, R a3 represents an alkylene group having 2 to 20 carbon atoms.

[0054] Regarding the alkyl group that can be selected as R a1 and R a2 Examples of the alkyl group include ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, 3,3,5-trimethylhexyl, n-decyl, dimethyloctyl, isodecyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, and n-eicosyl.

[0055] Further, regarding the alkenyl group that can be selected as R a1 and R a2 Examples of the alkenyl group include vinyl, n-propenyl, n-butenyl, n-hexenyl, n-octenyl, 2-ethylhexenyl, n-nonenyl, 3,3,5-trimethylhexenyl, n-decenyl, dimethyloctenyl, isodecenyl, n-undecenyl, n-dodecenyl, n-tridecenyl, n-tetradecenyl, n-pentadecenyl, n-hexadecenyl, n-octadecenyl, and n-eicosenyl.

[0056] It should be noted that the alkyl group or alkenyl group can be linear or branched.

[0057] Further, from the viewpoint of improving the effects of the present invention, etc., the number of carbon atoms of the alkyl group or alkenyl group is preferably 4 to 16, more preferably 5 to 14, and further preferably 6 to 12.

[0058] Further, regarding the alkylene group that can be selected as R a3 Examples of the alkylene group include ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, 2-ethylhexylene, n-nonylene, n-decylene, n-undecylene, n-tridecylene, n-hexadecylene, n-octadecylene, and n-eicosylene.

[0059] It should be noted that the alkylene group can be linear or branched.

[0060] Further, from the viewpoint of improving the effects of the present invention, etc., the number of carbon atoms of the alkylene group is preferably 4 to 16, more preferably 6 to 13, and further preferably 8 to 12.

[0061] The diester oil (A11) can be used alone in one kind or in combination of two or more kinds.

[0062] - Polyol ester oil (A12) -

[0063] The polyol ester oil (A12) is an ester which is a condensate of a polyol and a fatty acid.

[0064] From the viewpoint of improving heat resistance and the like, the number of carbon atoms of the polyol constituting the polyol ester oil (A12) is preferably 2 to 20, more preferably 2 to 15, and further preferably 2 to 12.

[0065] From the viewpoint of improving heat resistance and the like, the number of carbon atoms of the fatty acid constituting the polyol ester oil (A12) is preferably 2 to 20, more preferably 2 to 18, and further preferably 2 to 16.

[0066] Specific examples of the polyol constituting the polyol ester oil (A12) include diols such as ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, 2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol; polyols such as trimethylolethane, trimethylolpropane, trimethylolbutane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, glycerol, glycerol dimer, 1,3,5-pentanetriol, sorbitol, dehydrated sorbitol, adonitol, arabinitol, xylitol, and mannitol; and saccharides such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, and sorbose.

[0067] Among these, from the viewpoint of improving heat resistance and the like, trimethylolpropane, glycerol, pentaerythritol, and dipentaerythritol are preferred.

[0068] Specific examples of the fatty acid constituting the polyol ester oil (A12) include propionic acid, n-butyric acid, n-valeric acid (valeric acid), isovaleric acid (isovaleric acid), n-caproic acid (caproic acid), n-heptanoic acid, isoheptanoic acid, n-caprylic acid (caprylic acid), 2-ethylhexanoic acid, isooctanoic acid, n-nonanoic acid (nonanoic acid), isononanoic acid, n-decanoic acid (decanoic acid), isodecanoic acid, n-undecanoic acid, isoundecanoic acid, n-dodecanoic acid (lauric acid), isododecanoic acid, n-tridecanoic acid, isotridecanoic acid, n-tetradecanoic acid (myristic acid), n-hexadecanoic acid (palmitic acid), n-octadecanoic acid (stearic acid), isostearic acid, n-eicosanoic acid (arachidic acid), 10-undecenoic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, and gadoleic acid.

[0069] These fatty acids can be linear or branched.

[0070] In addition, these fatty acids can be saturated fatty acids or unsaturated fatty acids.

[0071] The polyol ester oil (A12) can be used alone as one kind, or two or more kinds can be used in combination.

[0072] - Aromatic ester oil (A13)-

[0073] The aromatic ester oil (A13) is an ester having one or more ester groups bonded to an aromatic ring, and is preferably a compound represented by the following general formula (a-3).

[0074] [Chemical formula 2]

[0075]

[0076] In the above general formula (a-3), m represents an integer of 1 to 5, preferably an integer of 2 to 4, and more preferably an integer of 3 to 4.

[0077] R a31 is an alkyl group having 2 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. It should be noted that the plurality of R a31 existing may be the same as each other or different from each other.

[0078] Regarding the alkyl group that can be selected as R a31 the alkyl groups exemplified as R a11 and R a12 can be cited.

[0079] Regarding the alkenyl group that can be selected as R a31 the alkenyl groups exemplified as R a11 and R a12 can be cited.

[0080] It should be noted that the alkyl group and the alkenyl group can be linear or branched.

[0081] In addition, from the viewpoint of improving heat resistance and the like, the number of carbon atoms of the alkyl group and the alkenyl group is preferably 4 to 16, more preferably 6 to 13, and further preferably 8 to 12.

[0082] The aromatic ester oil (A13) can be used alone as one kind, or two or more kinds can be used in combination.

[0083] (Suitable form of ester oil (A1))

[0084] In the lubricating oil composition of the present embodiment, the ester oil (A1) preferably contains a diester oil (A11).

[0085] Generally, esters having a hydrogen atom bonded to the β-position carbon atom on the alcohol side of the ester bond are liable to decompose when heated (Non-Patent Document 1: Tribology Series 8 Lubricating Greases and Synthetic Lubricants (Friction Science Library 8 Lubricating Greases and Synthetic Lubricants), Kogyo Shuppan Co., Ltd., December 25, 1983, First Edition First Printing).

[0086] According to the research of the present inventors, it has been confirmed that even esters having a hydrogen atom bonded to the β-position carbon atom on the alcohol side of the ester bond can improve the evaporation characteristics by the action of the phenothiazine-based compound (B).

[0087] Therefore, according to the formulation shown in the present embodiment, even when the ester oil (A1) contains an ester having a hydrogen atom bonded to the β-position carbon atom on the alcohol side of the ester bond, the evaporation characteristics of the lubricating oil composition can be made excellent.

[0088] Here, most of the diester oils (A11) have a hydrogen atom bonded to the β-position carbon atom on the alcohol side of the ester bond. Therefore, their evaporation characteristics are mostly poor.

[0089] Therefore, the formulation shown in the present embodiment (i.e., the lubricating oil composition of the present embodiment) is suitable for the case where the ester oil (A1) contains the diester oil (A11).

[0090] In addition, the formulation shown in the present embodiment is more suitable for the case where the diester oil (A11) is a diester oil (A11x) having a hydrogen atom bonded to the β-position carbon atom on the alcohol side of the ester bond.

[0091] Here, from the viewpoint of more easily enjoying the effects of the present invention, the content of the diester oil (A11) in the ester oil (A1) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, further preferably 70% by mass to 100% by mass, still further preferably 80% by mass to 100% by mass, yet further preferably 90% by mass to 100% by mass, and even further preferably 95% by mass to 100% by mass, based on the total amount of the ester oil (A1).

[0092] In addition, from the viewpoint of more easily enjoying the effects of the present invention, the content of the diester oil (A11x) in the ester oil (A1) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, further preferably 70% by mass to 100% by mass, still further preferably 80% by mass to 100% by mass, yet further preferably 90% by mass to 100% by mass, and even further preferably 95% by mass to 100% by mass, based on the total amount of the ester oil (A1).

[0093] (Base oil (A2) other than the ester-based oil (A1))

[0094] In the lubricating oil composition of the present embodiment, as the base oil (A), one or more base oils (A2) selected from synthetic oils and mineral oils other than ester oil (A1) may be contained.

[0095] Examples of the synthetic oil other than ester oil (A1) include polyolefins 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; various ethers such as polyalkylene glycols and polyphenyl ethers; alkylbenzenes; alkylnaphthalenes; base oils (GTL) obtained by isomerizing waxes produced from natural gas by the Fischer-Tropsch method or the like (Gas To Liquids WAX).

[0096] These synthetic oils may be used alone or in combination of two or more.

[0097] Examples of the mineral oil include atmospheric residue obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate crude oil, and naphthenic crude oil; distillate oil obtained by vacuum distillation of these atmospheric residues; mineral oil obtained by subjecting the distillate oil to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0098] These mineral oils may be used alone or in combination of two or more.

[0099] <Phenothiazine-based compound (B)>

[0100] The lubricating oil composition of the present embodiment contains a phenothiazine-based compound (B).

[0101] The phenothiazine-based compound (B) has the effect of improving the evaporation characteristics of the ester oil (A1). Moreover, this effect can be fully exerted even when the non-metal thiophosphate-based compound (C) is blended into the lubricating oil composition.

[0102] It should be noted that in this specification, "phenothiazine-based compound (B)" refers to one or more selected from phenothiazine (B1) and phenothiazine derivatives (B2).

[0103] (Phenothiazine (B1))

[0104] Phenothiazine (B1) is unsubstituted phenothiazine represented by the following structural formula (b-1).

[0105] [Chemical formula 3]

[0106]

[0107] (Phenothiazine derivative (B2))

[0108] The phenothiazine derivative (B2) is a compound in which at least one hydrogen atom of the unsubstituted phenothiazine represented by the above structural formula (b-1) is substituted by a substituent, and the compounds represented by the following general formula (b-2) can be preferably cited.

[0109] [Chemical formula 4]

[0110]

[0111] In the above general formula (b-2), R b1 , R b2 and R b3 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 11 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an acyl group having 1 to 10 carbon atoms, a hydroxyl group, a sulfone group, a nitro group, an amino group, a carboxyl group or a halogen.

[0112] In the above general formula (b-2), p1 and p2 are each independently an integer from 0 to 4.

[0113] When p1 is two or more, the multiple Rs b1 present may be the same as each other or different from each other.

[0114] In addition, when p2 is two or more, the multiple Rs b2 present may be the same as each other or different from each other.

[0115] The phenothiazine derivative (B2) can be used alone as one kind, or two or more kinds can be used in combination.

[0116] (Preferred form of the phenothiazine derivative (B2))

[0117] The phenothiazine derivative (B2) preferably satisfies one or more of the following conditions 1 to 4.

[0118] -Condition 1-

[0119] From the viewpoint of improving the solubility of the phenothiazine derivative (B2) in the base oil (A), R b1 , R b2 and R b3 are an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 11 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 10 carbon atoms or an acyl group having 1 to 10 carbon atoms.

[0120] -Condition 2-

[0121] R b1 , R b2 and R b3When it is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an acyl group having 1 to 10 carbon atoms, from the viewpoints of improving the solubility of the phenothiazine derivative (B2) in the base oil (A) and suppressing the precipitation of sludge, etc., the number of carbon atoms of these substituents is preferably 4 to 10, more preferably 6 to 10.

[0122] -Condition 3-

[0123] From the viewpoint of suppressing the oxidation of the phenothiazine derivative (B2) itself, one of the 3-position and 7-position of phenothiazine, preferably both, is introduced with R as b1 , R b2 and R b3 and the above-mentioned substituents listed.

[0124] -Condition 4-

[0125] From the viewpoint of suppressing the oxidation of the phenothiazine derivative (B2) itself, one of the 1-position and 2-position of phenothiazine, preferably both, is introduced with an acyl group having 1 to 10 carbon atoms.

[0126] (Content of phenothiazine-based compound (B))

[0127] In the lubricating oil composition of the present embodiment, from the viewpoint of more easily improving the evaporation characteristics of the lubricating oil composition, the content of the phenothiazine-based compound (B) is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.08% by mass or more based on the total amount of the lubricating oil composition. In addition, from the viewpoint of the balance between the content of the phenothiazine-based compound (B) and the effect of improving the evaporation characteristics, the content of the phenothiazine-based compound (B) is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and further preferably 2.5% by mass or less.

[0128] The upper limit value and the lower limit value of these numerical ranges can be arbitrarily combined. Specifically, it is preferably 0.01% by mass to 5.0% by mass, more preferably 0.05% by mass to 3.0% by mass, and further preferably 0.08% by mass to 2.5% by mass.

[0129] <Non-metallic thiophosphate-based compound (C)>

[0130] The lubricating oil composition of the present embodiment contains a non-metallic thiophosphate-based compound (C).

[0131] The non-metallic thiophosphate-based compound (C) can not only fully exert the role of improving the evaporation characteristics of the ester oil (A1) by using the phenothiazine-based compound (B), but also impart abrasion resistance to the lubricating oil composition.

[0132] As the non-metallic thiophosphate compound (C), compounds that do not contain metal atoms as constituent atoms and contain phosphorus atoms and sulfur atoms as constituent atoms can be cited. As such compounds, for example, one or more selected from thiophosphates, thiophosphites, and their amine salts, etc. can be cited.

[0133] Among these, from the viewpoint of improving the effects of the present invention, the non-metallic thiophosphate compound (C) preferably contains thiophosphates (C1).

[0134] As the thiophosphates (C1), one or more selected from monothiophosphates, dithiophosphates, trithiophosphates, etc. can be cited.

[0135] Among these, one or more selected from monothiophosphates and dithiophosphates are preferred.

[0136] It should be noted that the content of the thiophosphates (C1) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, further preferably 70% by mass to 100% by mass, still further preferably 80% by mass to 100% by mass, yet further preferably 90% by mass to 100% by mass, and even further preferably 95% by mass to 100% by mass based on the total amount of the non-metallic thiophosphate compound (C).

[0137] It should be noted that in this specification, "monothiophosphates" refers to thiophosphates or their derivatives in which the number of sulfur atoms bonded to the phosphorus atom is 1.

[0138] In addition, "dithiophosphates" refers to thiophosphates or their derivatives in which the number of sulfur atoms bonded to the phosphorus atom is 2.

[0139] In addition, "trithiophosphates" refers to thiophosphates or their derivatives in which the number of sulfur atoms bonded to the phosphorus atom is 3.

[0140] (Trithiophosphoric acid monoester (C1x))

[0141] Regarding the thiophosphates (C1), from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), as the monothiophosphates, it is preferable to contain one or more selected from the trithiophosphoric acid monoesters (C1x) represented by the following general formula (c-1x).

[0142] [Chemical formula 5]

[0143]

[0144] [In the above general formula (c-1x), each symbol is as follows.

[0145] R c1, R c2 and R c3 each independently represents an aliphatic hydrocarbon group having 1 to 18 carbon atoms, saturated or unsaturated, an alicyclic hydrocarbon group having 5 to 18 carbon atoms, saturated or unsaturated and optionally having substituents, or an aromatic hydrocarbon group having 5 to 18 carbon atoms and optionally having substituents.

[0146] In the above general formula (c-1x), as R c1 , R c2 and R c3 the number of carbon atoms of the optionally selected saturated or unsaturated aliphatic hydrocarbon group is more preferably 5 to 18.

[0147] Specific examples of the saturated aliphatic hydrocarbon group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl.

[0148] They may be linear or branched.

[0149] Examples of the unsaturated aliphatic hydrocarbon group include groups having at least 1 unsaturated bond such as vinyl and propenyl other than the above-mentioned methyl, which is a specific saturated aliphatic hydrocarbon group.

[0150] In the above general formula (c-1x), regarding R c1 , R c2 and R c3 specific examples of the optionally selected saturated alicyclic hydrocarbon group include cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl.

[0151] Examples of the unsaturated alicyclic hydrocarbon group include groups having at least 1 unsaturated bond such as cyclopentenyl and cyclohexenyl in the above-mentioned saturated alicyclic hydrocarbon group.

[0152] In the above general formula (c-1x), regarding R c1 , R c2 and R c3 specific examples of the optionally selected aromatic hydrocarbon group include aryl groups such as phenyl and naphthyl.

[0153] Examples of the substituent include, for example, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, and aryl groups of C 6 -C 14 .

[0154] As specific examples of the monothiophosphoric acid triester (C1x), tributyl thiophosphate, tripentyl thiophosphate, trihexyl thiophosphate, triheptyl thiophosphate, trioctyl thiophosphate, trinonyl thiophosphate, tridecyl thiophosphate, tris(undecyl) thiophosphate, tris(dodecyl) thiophosphate, tris(tridecyl) thiophosphate, tris(tetradecyl) thiophosphate, tris(pentadecyl) thiophosphate, tris(hexadecyl) thiophosphate, tris(heptadecyl) thiophosphate, tris(octadecyl) thiophosphate, trioleyl thiophosphate, triphenyl thiophosphate, tricresyl thiophosphate, tris(xylene) thiophosphate, tolyl diphenyl thiophosphate, dimethylphenyl diphenyl thiophosphate, tris(n-propylphenyl) thiophosphate, tris(isopropylphenyl) thiophosphate, tris(n-butylphenyl) thiophosphate, tris(isobutylphenyl) thiophosphate, tris(sec-butylphenyl) thiophosphate, and tris(tert-butylphenyl) thiophosphate, etc. can be cited.

[0155] It should be noted that from the viewpoints of improving the effects of the present invention and improving the hydrolysis resistance of the ester oil (A1), the content of the monothiophosphoric acid triester (C1x) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, further preferably 70% by mass to 100% by mass, still further preferably 80% by mass to 100% by mass, yet further preferably 90% by mass to 100% by mass, and even further preferably 95% by mass to 100% by mass based on the total amount of the thiophosphoric acid esters (C1).

[0156] The monothiophosphoric acid triester (C1x) can be used alone as one kind, or two or more kinds can be used in combination.

[0157] (monothiophosphoric acid triaryl ester (C11x))

[0158] From the viewpoints of improving the effects of the present invention and improving the hydrolysis resistance of the ester oil (A1), the monothiophosphoric acid triester (C1x) preferably contains one or more selected from the monothiophosphoric acid triaryl esters (C11x) represented by the following general formula (c-11x).

[0159] [Chemical formula 6]

[0160]

[0161] [In the above general formula (c-11x), each symbol is as follows.

[0162] R c11 、R c12 and R c13 each independently represents an alkyl group having 1 to 3 carbon atoms.

[0163] n1, n2, and n3 each independently represent an integer from 0 to 5.

[0164] In the above general formula (c-11x), R c11 , R c12 , and R c13 are each independently an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include methyl, ethyl, n-propyl, isopropyl, and the like.

[0165] n1, n2, and n3 are each independently preferably 0 to 2, more preferably 0 to 1, and still more preferably 0.

[0166] Specifically, examples of the triaryl monothiophosphate (C11x) represented by the above general formula (c-11x) include tricresyl thiophosphate and triphenyl thiophosphate.

[0167] It should be noted that from the viewpoints of improving the effects of the present invention and improving the hydrolysis resistance of the ester oil (A1), the content of the triaryl monothiophosphate (C11x) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, still more preferably 70% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, still even more preferably 90% by mass to 100% by mass, and yet even more preferably 95% by mass to 100% by mass, based on the total amount of the trithiophosphate (C1x).

[0168] The triaryl monothiophosphate (C11x) can be used alone as one kind or in combination of two or more kinds.

[0169] (Dithiophosphate (C1y) having a carboxyl group at the terminal)

[0170] Regarding the thiophosphates (C1), from the viewpoint of achieving good abrasion resistance, as the dithiophosphates, those preferably include dithiophosphates (C1y) having a carboxyl group at the terminal.

[0171] Specific examples of the dithiophosphate having a carboxyl group at the terminal include compounds represented by the following general formula (c-1y).

[0172] [Chemical formula 7]

[0173]

[0174] In the above general formula (c-1y), R c21 represents a linear or branched alkylene group having 1 to 8 carbon atoms. R c22 , and R c23 each independently represent a hydrocarbon group having 3 to 20 carbon atoms.

[0175] In the above general formula (c-1y), from the viewpoint of good solubility in the base oil (A), R c21 is preferably a linear or branched alkylene group having 1 to 8 carbon atoms, more preferably a linear or branched alkylene group having 2 to 4 carbon atoms, and still more preferably a branched alkylene group having 2 to 4 carbon atoms.

[0176] In addition, from the viewpoints of good solubility in the base oil (A) and improving abrasion resistance, R c22 and R c23 are preferably linear or branched alkyl groups having 3 to 8 carbon atoms, more preferably linear or branched alkyl groups having 4 to 6 carbon atoms. Specifically, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylbutyl, 1-methylpentyl, 1,3-dimethylbutyl, and 2-ethylhexyl can be mentioned. Among these, isobutyl and tert-butyl are preferred.

[0177] It should be noted that from the viewpoint of improving the effects of the present invention, the content of the dithiophosphate (C1y) having a carboxyl group at the terminal is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, still more preferably 70% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, still even more preferably 90% by mass to 100% by mass, and yet even more preferably 95% by mass to 100% by mass, based on the total amount of the thiophosphates (C1).

[0178] The dithiophosphate (C1y) having a carboxyl group at the terminal can be used alone or in combination of two or more.

[0179] (Content of the non-metallic thiophosphate compound (C))

[0180] In the lubricating oil composition of the present embodiment, from the viewpoint of more easily improving the abrasion resistance of the lubricating oil composition, the content of the non-metallic thiophosphate compound (C) is preferably 0.10% by mass or more, more preferably 0.50% by mass or more, and still more preferably 0.80% by mass or more, based on the total amount of the lubricating oil composition. In addition, from the viewpoint of the balance between the content of the non-metallic thiophosphate compound (C) and the effect of improving abrasion resistance, the content of the non-metallic thiophosphate compound (C) is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and still more preferably 2.5% by mass or less.

[0181] The upper limit and the lower limit of these numerical ranges can be arbitrarily combined. Specifically, it is preferably 0.10% by mass to 5.0% by mass, more preferably 0.50% by mass to 3.0% by mass, and still more preferably 0.80% by mass to 2.5% by mass.

[0182] Here, in the lubricating oil composition of the present embodiment, from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), the content of the dithiophosphate (C1y) having a carboxyl group at the terminal is preferably low. Specifically, the content of the dithiophosphate (C1y) having a carboxyl group at the terminal is preferably less than 0.95% by mass, more preferably less than 0.5% by mass, further preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, and still more preferably does not contain the dithiophosphate (C1y) having a carboxyl group at the terminal, based on the total amount of the lubricating oil composition.

[0183] <Content ratio of component (B) and component (C)>

[0184] From the viewpoint of improving the effect of the present invention, the content ratio [(B) / (C)] of the phenothiazine compound (B) to the non-metallic thiophosphate compound (C) is preferably 1 / 10 to 10 / 1, more preferably 1 / 8 to 8 / 1, and further preferably 1 / 6 to 6 / 1 in terms of mass ratio.

[0185] <Metal deactivator (D)>

[0186] From the viewpoint of improving the hydrolysis resistance of the ester oil (A1), the lubricating oil composition of the present embodiment preferably further contains a metal deactivator (D).

[0187] It should be noted that in the following description, the "metal deactivator (D)" will also be referred to as "component (D)".

[0188] Examples of the metal deactivator (D) include triazole compounds, thiadiazole compounds, imidazole compounds, and pyrimidine compounds.

[0189] They can be used alone or in combination of two or more.

[0190] (Benzotriazole compound (D1))

[0191] Here, from the viewpoint of further improving the hydrolysis resistance of the ester oil (A1), the metal deactivator (D) preferably contains a triazole compound, and more preferably contains a benzotriazole compound (D1) represented by the following general formula (d-1).

[0192] [Chemical formula 8]

[0193]

[0194] In the above general formula (d-1), R d1is an alkyl group having 1 to 4 carbon atoms. This alkyl group may be linear or branched. Here, from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), the number of carbon atoms of this alkyl group is preferably 1 to 3, more preferably 1 to 2, and still more preferably 1.

[0195] In the above general formula (d-1), q is an integer from 0 to 4. When there are multiple Rs d1 (that is, when q is an integer from 2 to 4), the multiple Rs d1 may be the same as each other or different from each other. Here, from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), q is preferably 0 to 3, more preferably 0 to 2, and still more preferably 1.

[0196] In the above general formula (d-1), R d2 is methylene or ethylene. Here, from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), R d2 is preferably methylene.

[0197] In the above general formula (d-1), R d3 and R d4 are each independently a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. This alkyl group may be linear or branched, and from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), it is preferably branched. In addition, from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), the number of carbon atoms of this alkyl group is preferably 2 to 14, more preferably 4 to 12, and still more preferably 6 to 10.

[0198] Here, from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), the content of the benzotriazole-based compound (D1) in the metal deactivator (D) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, still more preferably 70% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, still further preferably 90% by mass to 100% by mass, and yet further preferably 95% by mass to 100% by mass, based on the total amount of the metal deactivator (D).

[0199] From the viewpoint of improving the hydrolysis resistance of the ester oil (A1), the content of the metal deactivator (D) is preferably 0.01% by mass to 2.0% by mass, more preferably 0.05% by mass to 1.5% by mass, and still more preferably 0.08% by mass to 1.0% by mass, based on the total amount of the lubricating oil composition.

[0200] <Lubricating oil additive>

[0201] The lubricating oil composition of the present embodiment may further contain lubricating oil additives other than component (B), component (C), and component (D) as needed.

[0202] Examples of such lubricating oil additives include antioxidants (e.g., amine-based antioxidants and phenol-based antioxidants), metal detergents, dispersants, friction modifiers, antiwear agents other than non-metal thiophosphate compounds (C) (e.g., zinc dialkyldithiophosphate), extreme pressure agents, viscosity index improvers, pour point depressants, antifoaming agents, rust inhibitors, and antistatic agents.

[0203] Among these, it is preferable to contain dispersants such as succinimide-based dispersants and viscosity index improvers such as polymethacrylates.

[0204] The lubricating oil additives can be used singly or in combination of two or more.

[0205] The content of each of these lubricating oil additives can be appropriately adjusted within the range that does not impair the effects of the present invention. Based on the total amount (100% by mass) of the lubricating oil composition, each additive is generally 0.001 to 15% by mass, preferably 0.005 to 10% by mass, and more preferably 0.01 to 5% by mass, respectively and independently.

[0206] Here, in the lubricating oil composition of the present embodiment, from the viewpoint of improving evaporation characteristics, it is preferable that the content of the phenol-based antioxidant is small.

[0207] Examples of the phenol-based antioxidant include monophenol-based antioxidants and bisphenol-based antioxidants.

[0208] Examples of the monophenol-based antioxidant include alkyl-3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl) propionate such as n-octyl-3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl) propionate, 6-methylheptyl-3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl) propionate, and n-octadecyl-3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl) propionate (as the alkyl group, an alkyl group having 4 to 20 carbon atoms is exemplified, and preferably 8 to 18 carbon atoms); 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, etc., 2,6-di-tert-butyl-4-alkylphenol (the alkyl group has 1 to 4 carbon atoms); 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-amyl-p-cresol, etc.

[0209] In addition, as bisphenol antioxidants, examples include 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-bis(2,6-di-tert-butylphenol), 4,4'-bis(2-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4,4'-isopropylidenebis(2,6-di-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-nonylphenol), 2,2'-isobutylidenebis(4,6-dimethylphenol), 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 4,4'-thiobis(2-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), bis(3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], and the like.

[0210] The content of the phenolic antioxidant is preferably less than 0.5% by mass, more preferably less than 0.1% by mass, further preferably less than 0.01% by mass, and even more preferably free of phenolic antioxidants, based on the total amount of the lubricating oil composition.

[0211] In addition, in the lubricating oil composition of the present embodiment, from the viewpoint of improving the hydrolysis resistance of the ester oil (A1), the content of the thiocarbamate compound as an antiwear agent other than the metal thiophosphate compound (C) is preferably small.

[0212] Examples of the thiocarbamate compound include thiocarbamate compounds and dithiocarbamate compounds.

[0213] Examples of the thiocarbamate compound include diethylthiocarbamic acid, methylene diethylthiocarbamate, ethylidene diethyldithiocarbamate, dipropylthiocarbamic acid, methylene dipropylthiocarbamate, ethylidene dipropyldithiocarbamate, dibutyldithiocarbamic acid, methylene dibutyldithiocarbamate, ethylidene dibutyldithiocarbamate, dipentyldithiocarbamic acid, methylene dipentyldithiocarbamate, ethylidene dipentyldithiocarbamate, methylene dihexyldithiocarbamate, and ethylidene dihexyldithiocarbamate.

[0214] Examples of the dithiocarbamate compound include methylene bis(diethylthiocarbamate), ethylene bis(diethyldithiocarbamate), methylene bis(dipropylthiocarbamate), ethylene bis(dipropyldithiocarbamate), methylene bis(dibutylthiocarbamate), ethylene bis(dibutyldithiocarbamate), methylene bis(diisopentylthiocarbamate), ethylene bis(diisopentyldithiocarbamate), methylene bis(dihexylthiocarbamate), and ethylene bis(dihexylthiocarbamate).

[0215] The content of the thiocarbamate compound is preferably less than 1.0% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, and even more preferably the thiocarbamate compound is not contained, based on the total amount of the lubricating oil composition.

[0216] In addition, in the lubricating oil composition of the present embodiment, the content of the molybdenum-based friction modifier is preferably small.

[0217] Examples of the molybdenum-based friction modifier include molybdenum dithiocarbamate (MoDTC) and molybdenum dithiophosphate (MoDTP).

[0218] The content of the molybdenum-based friction modifier is preferably less than 0.5% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, and even more preferably the molybdenum-based friction modifier is not contained, based on the total amount of the lubricating oil composition.

[0219] [Physical properties of the lubricating oil composition]

[0220] [Evaporation characteristics]

[0221] The longer the evaporation life of the lubricating oil composition of the present embodiment measured by the method described in the following examples, the more preferable. Specifically, it is preferably 10 days or more, more preferably 12 days or more, still more preferably 14 days or more.

[0222] [Wear resistance]

[0223] The smaller the wear scar diameter of the lubricating oil composition of the present embodiment measured by the method described in the following examples, the more preferable. Specifically, it is preferably 0.90 mm or less, more preferably 0.80 mm or less, still more preferably 0.70 mm or less, even more preferably 0.60 mm or less, and still even more preferably 0.50 mm or less.

[0224] [Hydrolysis resistance (acid value, copper dissolution amount)]

[0225] The lower the acid value of the oil component of the lubricating oil composition of the present embodiment, as measured by the method described in the following examples, the more preferable. The lower the acid value, the more excellent the hydrolysis resistance. Specifically, it is preferably 5.00 mgKOH / g or less, more preferably 4.00 mgKOH / g or less, and further preferably 3.70 mgKOH / g or less.

[0226] The less the copper elution amount of the oil component of the lubricating oil composition of the present embodiment, as measured by the method described in the following examples, the more preferable. The less the copper elution amount, the more excellent the hydrolysis resistance. Specifically, it is preferably 20 mass ppm or less, more preferably 15 mass pp or less, and further preferably 10 mass ppm or less.

[0227] <Kinematic viscosity, viscosity index>

[0228] The kinematic viscosity of the lubricating oil composition of the present embodiment at 100 °C is preferably 2.0 mm 2 / s to 30.0 mm 2 / s, more preferably 2.5 mm 2 / s to 25.0 mm 2 / s, further preferably 3.0 mm 2 / s to 22.0 mm 2 / s.

[0229] The viscosity index of the lubricating oil composition of the present embodiment is preferably 90 or more.

[0230] It should be noted that the kinematic viscosity and viscosity index of the lubricating oil composition are values measured and calculated in accordance with JIS K2283:2000.

[0231] [Manufacturing method of lubricating oil composition]

[0232] The manufacturing method of the lubricating oil composition of the present embodiment is not particularly limited.

[0233] For example, the manufacturing method of the lubricating oil composition of the present embodiment includes: a step of mixing a base oil (A) containing an ester oil (A1), a phenothiazine compound (B), and a non-metallic thiophosphate compound (C).

[0234] As a method of mixing the base oil (A) containing the ester oil (A1), the phenothiazine compound (B), and the non-metallic thiophosphate compound (C), there is no particular limitation, and examples thereof include a method of blending the phenothiazine compound (B) and the non-metallic thiophosphate compound (C) into the base oil (A) containing the ester oil (A1).

[0235] In the case of compounding additives other than the phenothiazine compound (B) and the non-metallic thiophosphate compound (C), the additives may be compounded simultaneously with the phenothiazine compound (B) and the non-metallic thiophosphate compound (C), or may be compounded separately. Further, each component may be compounded after adding a diluent oil or the like to form a solution (dispersion) form.

[0236] Preferably, after compounding each component, it is stirred by a known method to be uniformly dispersed.

[0237] It should be noted that the preferred modes of the above-mentioned respective components are as described above.

[0238] [Use of the lubricating oil composition]

[0239] The lubricating oil composition of the present embodiment is excellent in evaporation characteristics and abrasion resistance.

[0240] Therefore, the lubricating oil composition of the present embodiment can be used for all applications requiring evaporation characteristics and abrasion resistance, and can be particularly suitably used for oil-impregnated bearings assembled in devices such as automotive electrical equipment, home electrical appliances, and OA office equipment.

[0241] Thus, according to the lubricating oil composition of the present embodiment, the following (1) to (3) can be provided.

[0242] (1) The lubricating oil composition of the present embodiment, which is used as an impregnating bearing oil.

[0243] (2) A method of using the lubricating oil composition, wherein the lubricating oil composition of the present embodiment is used as an impregnating bearing oil.

[0244] (3) An oil-impregnated bearing impregnated with the lubricating oil composition of the present embodiment.

[0245] In addition, in the present embodiment, the following methods (4) to (6) can also be provided.

[0246] (4) A method of improving the evaporation characteristics of the ester oil (A1) by compounding the phenothiazine compound (B) into the ester oil (A1).

[0247] (5) A method of improving the evaporation characteristics of the diester oil (A11) by compounding the phenothiazine compound (B) into the diester oil (A11).

[0248] (6) A method of improving the evaporation characteristics of the diester oil (A11), which is a diester oil having a hydrogen atom bonded to the β-position carbon atom on the alcohol side of the ester bond, by compounding the phenothiazine compound (B) into the diester oil.

[0249] In addition, the lubricating oil composition of the present embodiment is not limited to the use in oil-impregnated bearings, and can also be suitably used, for example, in hydrodynamic bearings of spindle motors used in electronic devices such as hard disk drives.

[0250] [One aspect of the present invention provided]

[0251] In one aspect of the present invention, the following [1] to

[11] are provided.

[0252] [1] A lubricating oil composition comprising: a base oil (A) containing an ester oil (A1), a phenothiazine compound (B), and a non-metallic thiophosphate compound (C).

[0253] [2] The lubricating oil composition according to [1] above, wherein the ester oil (A1) contains a diester oil (A11).

[0254] [3] The lubricating oil composition according to [1] or [2] above, wherein the non-metallic thiophosphate compound (C) contains thiophosphates (C1).

[0255] [4] The lubricating oil composition according to [3] above, wherein the thiophosphates (C1) contain one or more selected from the monothiophosphoric acid triesters (C1x) represented by the following general formula (c-1x).

[0256] [Chemical formula 9]

[0257]

[0258] [In the above general formula (c-1x), each symbol is as follows.

[0259] R c1 、R c2 and R c3 each independently represents a saturated or unsaturated aliphatic hydrocarbon group having 1 to 18 carbon atoms, a saturated or unsaturated alicyclic hydrocarbon group having 5 to 18 carbon atoms which may have a substituent, or an aromatic hydrocarbon group having 5 to 18 carbon atoms which may have a substituent.]

[0260] [5] The lubricating oil composition according to [4] above, wherein the monothiophosphoric acid triesters (C1x) contain one or more selected from the monothiophosphoric acid triaryl esters (C11x) represented by the following general formula (c-11x).

[0261] [Chemical formula 10]

[0262]

[0263] [In the above general formula (c-11x), each symbol is as follows.

[0264] R c11 , R c12 and R c13 Each independently represents an alkyl group having 1 to 3 carbon atoms.

[0265] n1, n2 and n3 each independently represent an integer of 0 to 5.]

[0266] [6] The lubricating oil composition according to any one of [1] to [5] above, further comprising a metal inactivating agent (D).

[0267] [7] The lubricating oil composition according to any one of [1] to [6] above, wherein the content ratio [(B) / (C)] of the phenothiazine compound (B) to the non-metallic thiophosphate compound (C) is 1 / 10 to 10 / 1 in terms of mass ratio.

[0268] [8] The lubricating oil composition according to any one of [1] to [7] above, which is used as an impregnation bearing oil.

[0269] [9] The method for using the lubricating oil composition, wherein the lubricating oil composition according to any one of [1] to [7] is used as an impregnation bearing oil.

[0270]

[10] An oil-impregnated bearing impregnated with the lubricating oil composition according to any one of [1] to [7] above.

[0271]

[11] A method for producing a lubricating oil composition, comprising: mixing a base oil (A) containing an ester oil (A1), a phenothiazine compound (B), and a non-metallic thiophosphate compound (C).

[0272] Example

[0273] The present invention is specifically described by the following examples, but the present invention is not limited to the following examples.

[0274] [Measurement methods of various physical property values]

[0275] The raw materials used in the examples and comparative examples and the properties of the lubricating oil compositions of the examples and comparative examples were measured in the following manner.

[0276] (1) Kinematic viscosity and viscosity index

[0277] The measurement and calculation were performed in accordance with JIS K2283:2000.

[0278] [Examples 1 to 2, Comparative Examples 1 to 5]

[0279] Mix the above components to prepare a lubricating oil composition having the composition shown in Table 1, and conduct the evaluation described below.

[0280] It should be noted that the numerical unit of the compounding composition in Table 1 is "mass %".

[0281] Details of each component used to prepare the lubricating oil composition having the composition shown in Table 1 are described below.

[0282] <Base oil (A)>

[0283] Use bis(2-ethylhexyl) dodecanedioate (DODN).

[0284] Bis(2-ethylhexyl) dodecanedioate is a base oil conforming to diester oil (A11), and is a compound in which R a1 and R a2 in the above general formula (a-1) are 2-ethylhexyl, and R a3 is a decylene group (-(CH 2 ) 10 -). A hydrogen atom is bonded to the β-position carbon atom on the alcohol side of the ester bond in this compound.

[0285] The kinematic viscosity at 40 °C is 13.9 mm 2 / s, the kinematic viscosity at 100 °C is 3.71 mm 2 / s, and the viscosity index is 163.

[0286] <Phenothiazine compound (B)>

[0287] Use phenothiazine.

[0288] Phenothiazine is an unsubstituted phenothiazine conforming to phenothiazine (B1).

[0289] <Non-phenothiazine compound (B')>

[0290] For comparison with the phenothiazine compound (B), use the following two compounds known as antioxidants.

[0291] · Amine compound: 4,4'-bis(α,α-dimethylbenzyl) diphenylamine

[0292] · Phenol compound: n-octadecyl 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate

[0293] <Non-metallic thiophosphate compound (C)>

[0294] Use triphenyl thiophosphate (TPPT).

[0295] Triphenyl thiophosphate is a compound that conforms to triaryl monothiophosphates (C11x), and is a compound in which n1, n2, and n3 in the above general formula (c-11x) are 0.

[0296] <Metal deactivator (D)>

[0297] A benzotriazole compound represented by the following structural formula is used.

[0298] The benzotriazole compound represented by the following structural formula is a compound that conforms to benzotriazole compounds (D1), and in the above general formula (d-1), R d1 is methyl, q is 1, R d2 is methylene, R d3 and R d4 are 2-ethylhexyl compounds.

[0299] [Chemical formula 11]

[0300]

[0301] <Other additives>

[0302] · Viscosity index improver: polymethacrylate (weight average molecular weight: 300,000, resin component: 19% by mass, diluent oil: diester oil (isodecyl sebacate))

[0303] · Dispersant: succinimide dispersant (succinimide: 53% by mass, components other than succinimide: deuterated alkane (diluent) and polybutene)

[0304] <Evaluation 1: Evaluation of evaporation characteristics>

[0305] For the lubricating oil compositions of Examples 1 to 2 and Comparative Examples 1 to 5, the evaporation characteristics were evaluated according to the following steps.

[0306] A constant temperature bath specified in the test method for thermal stability of lubricating oils (JIS K2540: 2000) and equipped with a turntable (manufactured by Yoshida Scientific Instruments Co., Ltd., model TST-9R) was used.

[0307] A glass container with an inner diameter of 53 mm and a depth of 56 mm was used as the sample container.

[0308] After measuring 2.0 g (±0.010 g) of the lubricating oil composition to be evaluated and 2.0 g (±0.010 g) of iron powder or copper powder into the sample container, it was left standing in a constant temperature bath heated to 150 °C, taken out at a time that is a multiple of 24 hours, and weighed.

[0309] The evaporation rate (weight %) is calculated based on the weight before and after the test, and the time (days) until the evaporation rate starts to rise sharply is defined as the evaporation life. Specifically, when the change amount (a) of the evaporation rate (y) with respect to the number of test days (x) is represented by the regression line y = ax, the determination coefficient R 2 The number of test days less than 0.9 is defined as the evaporation life.

[0310] The longer the evaporation life, the more excellent the evaporation characteristics of the lubricating oil composition. Conversely, the shorter the evaporation life, the poorer the evaporation characteristics of the lubricating oil composition.

[0311] In this example, a lubricating oil composition with an evaporation life of 10 days or more is considered qualified.

[0312] It should be noted that for the lubricating oil compositions of Comparative Examples 2 to 5, the evaluation using copper powder was not carried out.

[0313] <Evaluation 2: Evaluation of Abrasion Resistance>

[0314] For the lubricating oil compositions of Examples 1 to 2 and Comparative Example 1, the abrasion resistance was evaluated according to the following steps.

[0315] Using a 0.5-inch ball made of SUJ-2 of grade 20, the wear scar diameter (mm) of the fixed ball after the shell four-ball wear test carried out under the conditions of an oil temperature of 80 °C, a rotation speed of 1200 rpm, a load of 392 N, and a test time of 60 minutes was measured.

[0316] The smaller the wear scar diameter, the more excellent the abrasion resistance of the lubricating oil composition. Conversely, the larger the wear scar diameter, the poorer the abrasion resistance of the lubricating oil composition.

[0317] In this example, a lubricating oil composition with a wear scar diameter of 0.90 mm or less is considered qualified.

[0318] The results of Evaluation 1 and Evaluation 2 are shown in Table 1.

[0319] It should be noted that "<" in Table 1 means "exceed".

[0320]

[0321] From Table 1, the following conclusions can be drawn.

[0322] It can be seen that the evaporation characteristics and abrasion resistance of the lubricating oil compositions of Examples 1 to 2 are both excellent.

[0323] In contrast, it can be seen that the lubricating oil composition of Comparative Example 1 can ensure abrasion resistance but has poor evaporation characteristics. It can be seen that the evaporation characteristics of the lubricating oil compositions of Comparative Examples 2 to 5 are all poor.

[0324] <Evaluation 3: Evaluation of Hydrolysis Resistance>

[0325] For the lubricating oil compositions of Examples 1 to 2 and Comparative Example 1, the hydrolysis resistance was evaluated according to the following steps.

[0326] Using a rotating bomb oxidation stability tester (RBOT) and a sample container (beaker for RBOT test) specified in JIS K 2514-3:2003, the lubricating oil composition to be evaluated was tested under the following conditions. After the test, the oil and water in the sample container were separated, and the acid value and copper dissolution amount of the oil were evaluated. It should be noted that the acid value and copper dissolution amount of the lubricating oil composition before the test were also measured.

[0327] (Test Conditions)

[0328] · Sample oil volume: 20 g

[0329] · Catalyst: 120 mg of copper powder

[0330] · Water: 1 mL inside the beaker and 1 mL outside the beaker

[0331] · Enclosure: Air (atmospheric pressure)

[0332] · Temperature: 150 °C

[0333] · Test time: 24 hours

[0334] The acid value of the oil was measured by the potentiometric method using a TS1700 manufactured by HIRANUMA Corporation in accordance with JIS K2501:2003.

[0335] In addition, the copper dissolution amount of the oil was measured by ICP emission spectrometry using an ICPS-8100 manufactured by Shimadzu Corporation.

[0336] The lower the acid value of the oil, the better the hydrolysis resistance. Conversely, the higher the acid value of the oil, the worse the hydrolysis resistance.

[0337] In addition, the less the copper dissolution amount of the oil, the better the hydrolysis resistance. Conversely, the more the copper dissolution amount of the oil, the worse the hydrolysis resistance.

[0338] In this example, a lubricating oil composition with an acid value of 5.00 mg KOH / g or less and a copper dissolution amount of 20 mass ppm or less in the oil after 24 hours was considered qualified.

[0339] The results of Evaluation 3 are shown in Table 2.

[0340] It should be noted that ">" in Table 2 means "less than".

[0341] [Table 2]

[0342]

[0343] As can be seen from Table 2, the hydrolysis resistance of the lubricating oil compositions of Examples 1 to 2 is excellent.

Claims

1. A lubricating oil composition comprising: a base oil (A) containing an ester oil (A1), a phenothiazine compound (B), and a non-metallic thiophosphate compound (C).

2. The lubricating oil composition according to claim 1, wherein, the ester oil (A1) contains a diester oil (A11).

3. The lubricating oil composition according to claim 1 or 2, wherein, the non-metallic thiophosphate compound (C) contains thiophosphates (C1).

4. The lubricating oil composition according to claim 3, wherein, the thiophosphates (C1) contain one or more selected from the monothiophosphoric acid triesters (C1x) represented by the following general formula (c-1x), [Chemical formula 1] In the general formula (c-1x), each symbol is as follows: R c1 、R c2 and R c3 each independently represents an aliphatic hydrocarbon group having 1 to 18 carbon atoms, saturated or unsaturated, an alicyclic hydrocarbon group having 5 to 18 carbon atoms, saturated or unsaturated and optionally having substituents, or an aromatic hydrocarbon group having 5 to 18 carbon atoms and optionally having substituents.

5. The lubricating oil composition according to claim 4, wherein, the monothiophosphoric acid triesters (C1x) contain one or more selected from the monothiophosphoric acid triaryl esters (C11x) represented by the following general formula (c-11x), [Chemical formula 2] In the general formula (c-11x), each symbol is as follows: R c11 、R c12 and R c13 each independently represents an alkyl group having 1 to 3 carbon atoms, n1, n2 and n3 each independently represent an integer of 0 to 5.

6. The lubricating oil composition according to any one of claims 1 to 5, further comprising a metal deactivator (D).

7. The lubricating oil composition according to any one of claims 1 to 6, wherein, the content ratio [(B) / (C)] of the phenothiazine compound (B) to the non-metallic thiophosphate compound (C) is 1 / 10 to 10 / 1 by mass ratio.

8. The lubricating oil composition according to any one of claims 1 to 7, which is used as an impregnated bearing oil.

9. A method for using the aforementioned lubricating oil composition, wherein, the lubricating oil composition according to any one of claims 1 to 7 is used as an impregnated bearing oil.

10. An oil-impregnated bearing impregnated with the lubricating oil composition according to any one of claims 1 to 7.

11. A method for manufacturing a lubricating oil composition, which comprises: a step of mixing a base oil (A) containing an ester oil (A1), a phenothiazine compound (B), and a non-metallic thiophosphate compound (C).

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