Lubricating oil base oil

Abstract

A lubricant base oil according to the present invention contains an ester compound which has a structural moiety (A) that is derived from an alcohol compound (A) and a structural moiety (B) that is derived from a carboxylic acid; and the structural moiety (B) comprises a structural moiety (B1) that is derived from a monocarboxylic acid (B1) and a structural moiety (B2) that is derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms. The present invention is capable of providing a lubricant base oil that has excellent stability at low temperatures and high heat resistance, while maintaining low torque properties.

Description

[Technical Field]

[0001] The present invention relates to lubricant base oils, lubricants, and methods for producing lubricant base oils. [Background technology]

[0002] Lubricating oils are required to have low torque, low temperature stability, and high heat resistance.

[0003] JP 2018-100369 A describes a lubricating base oil in which a pentaerythritol ester compound has a benzoyloxy group or a naphthoyloxy group in its structure, which makes the lubricating base oil highly heat-resistant and resistant to thermal degradation even at high temperatures.

[0004] Japanese Patent Application Laid-Open No. 2017-174221 describes a lubricating oil composition that can reduce volatilization under high temperature conditions by combining a specific phenolic antioxidant and an amine-based antioxidant with an ester-based synthetic oil having a specific viscosity. Summary of the Invention

[0005] The present invention provides a lubricating base oil comprising an ester compound having a structural moiety (A) derived from an alcohol compound (A) represented by the following general formula (1) and a structural moiety (B) derived from a carboxylic acid, wherein the structural moiety (B) includes a structural moiety (B1) derived from a monocarboxylic acid (B1) represented by the following general formula (2) and a structural moiety (B2) derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms: [ka] (In general formula (1), R 1 is a hydroxyl group, and R 2 From R 4 are independently a hydroxyl group, a hydrogen atom, or a saturated hydrocarbon group having 1 to 3 carbon atoms. [ka] (In general formula (2), R 5From R 9 Any one of the groups is a carboxyl group, -CH2-COOH, or -CH2-CH2-COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having from 1 to 10 carbon atoms.) Detailed Description of the Invention

[0006] It has been difficult to achieve both low temperature stability and high heat resistance with conventional lubricating base oils.

[0007] The present invention provides a lubricating base oil that is excellent in low temperature stability and high heat resistance while maintaining low torque properties.

[0008] The present invention provides a lubricating base oil comprising an ester compound having a structural moiety (A) derived from an alcohol compound (A) represented by the following general formula (1) and a structural moiety (B) derived from a carboxylic acid, wherein the structural moiety (B) includes a structural moiety (B1) derived from a monocarboxylic acid (B1) represented by the following general formula (2) and a structural moiety (B2) derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms: [ka] (In general formula (1), R 1 is a hydroxyl group, and R 2 From R 4 are independently a hydroxyl group, a hydrogen atom, or a saturated hydrocarbon group having 1 to 3 carbon atoms. [ka] (In general formula (2), R 5 From R 9 is a carboxyl group, -CH-COOH, or -CH-CH-COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having from 1 to 10 carbon atoms.

[0009] According to the present invention, it is possible to provide a lubricating base oil that is excellent in low temperature stability and high heat resistance while maintaining low torque properties.

[0010] An embodiment of the present invention will be described below.

[0011] <Lubricant base oil> The lubricating base oil of this embodiment contains an ester compound having a structural moiety (A) derived from an alcohol compound (A) represented by the following general formula (1) and a structural moiety (B) derived from a carboxylic acid, wherein the structural moiety (B) includes a structural moiety (B1) derived from a monocarboxylic acid (B1) represented by the following general formula (2) and a structural moiety (B2) derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms: [ka] (In general formula (1), R 1 is a hydroxyl group, and R 2 From R 4 are independently a hydroxyl group, a hydrogen atom, or a saturated hydrocarbon group having 1 to 3 carbon atoms. [ka] (In general formula (2), R 5 From R 9 is a carboxyl group, -CH-COOH, or -CH-CH-COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having from 1 to 10 carbon atoms.

[0012] The lubricating base oil of this embodiment maintains low torque and has excellent low-temperature stability and high heat resistance. Although the reason why the lubricating base oil exhibits such effects is unclear, it is believed that the presence of the above-described structure in the ester molecular skeleton reduces crystallinity and suppresses thermal decomposition, thereby achieving both low-temperature stability and high heat resistance while maintaining low torque.

[0013] [Ester compounds] [Structural part (A)] The structural moiety (A) is a structural moiety derived from the alcohol compound (A) represented by the general formula (1).

[0014] In the general formula (1), R 1 is a hydroxyl group, and R 2 From R 4 are independently a hydroxyl group, a hydrogen atom, or a saturated hydrocarbon group having 1 to 3 carbon atoms. 2 From R 4 From the viewpoint of achieving both low torque and high heat resistance, preferably at least one of the groups is a hydroxyl group, more preferably at least two of the groups are hydroxyl groups, and even more preferably all of the groups are hydroxyl groups.

[0015] Examples of the alcohol compound (A) include pentaerythritol, trimethylolpropane, trimethylolethane, neopentyl glycol, etc. From the viewpoint of achieving both low torque and high heat resistance, the alcohol compound (A) is preferably at least one selected from pentaerythritol, trimethylolpropane, and neopentyl glycol, more preferably at least one selected from pentaerythritol and trimethylolpropane, and even more preferably pentaerythritol.

[0016] [Structural part (B)] The structural moiety (B) is a structural moiety derived from a carboxylic acid, and includes the structural moiety (B1) and the structural moiety (B2).

[0017] (Structural site (B1)) The structural moiety (B1) is a structural moiety derived from the monocarboxylic acid (B1) represented by the general formula (2). 5 From R 9 Any one of R is a carboxyl group, -CH2-COOH, or -CH2-CH2-COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having 1 to 10 carbon atoms. 5 From R 9 From the viewpoint of torque reduction, any one of R is preferably a carboxyl group or —CH—COOH, and more preferably a carboxyl group. 5From R 9 are preferably each independently a hydroxyl group or a saturated hydrocarbon group having from 1 to 10 carbon atoms, more preferably a saturated hydrocarbon group having from 1 to 10 carbon atoms, from the viewpoint of achieving both low torque and high heat resistance. The number of carbon atoms in the saturated hydrocarbon group is preferably 2 or more, more preferably 4 or more, from the viewpoint of achieving both low torque and high heat resistance, and is preferably 6 or less, more preferably 4 or less, from the viewpoint of achieving both low torque and high heat resistance.

[0018] In the general formula (2), preferably, R 7 is a carboxyl group, -CH2-COOH, or -CH2-CH2-COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having 1 to 10 carbon atoms. 7 is preferably a carboxyl group or —CH—COOH, and more preferably a carboxyl group. 5 , R 6 , R 8 and R 9 are preferably each independently a hydroxyl group or a saturated hydrocarbon group having from 1 to 10 carbon atoms, more preferably a saturated hydrocarbon group having from 1 to 10 carbon atoms, from the viewpoint of achieving both low torque and high heat resistance. The number of carbon atoms in the saturated hydrocarbon group is preferably 2 or more, more preferably 4 or more, from the viewpoint of achieving both low torque and high heat resistance, and is preferably 6 or less, more preferably 4 or less, from the viewpoint of achieving both low torque and high heat resistance.

[0019] Examples of the monocarboxylic acid (B1) include 3-hydroxybenzoic acid, 5-methyl-3-hydroxybenzoic acid, 5-ethyl-3-hydroxybenzoic acid, 4-ethyl-3-hydroxybenzoic acid, 5-isopropyl-3-hydroxybenzoic acid, 6-isopropyl-3-hydroxybenzoic acid, 5-n-butyl-3-hydroxybenzoic acid, 5-tert-butyl-3-hydroxybenzoic acid, 5-sec-butyl-3-hydroxybenzoic acid, 5-isoheptyl-3- Hydroxybenzoic acid, 5-isohexyl-3-hydroxybenzoic acid, 5-isooctyl-3-hydroxybenzoic acid, 4-methoxy-3-hydroxybenzoic acid, 4-ethoxy-3-hydroxybenzoic acid, 6-butoxy-3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 6-methyl-4-hydroxybenzoic acid, 6-ethyl-4-hydroxybenzoic acid, 6-isopropyl-4-hydroxybenzoic acid, 6-tert-butyl-4-hydroxybenzoic acid, 6 -sec-Butyl-4-hydroxybenzoic acid, 6-isohexyl-4-hydroxybenzoic acid, 6-isoheptyl-4-hydroxybenzoic acid, 6-isooctyl-4-hydroxybenzoic acid, 5-n-propyl-4-hydroxybenzoic acid, 5-methoxy-4-hydroxybenzoic acid, 6-butoxy-4-hydroxybenzoic acid, 5-ethoxy-4-hydroxybenzoic acid, 3-tert-butyl-4-hydroxybenzoic acid, 3-isooctyl-4-hydroxybenzoic acid hydroxybenzoic acids such as benzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, 5,6-di-tert-butyl-4-hydroxybenzoic acid, 2-hydroxybenzoic acid, 3-methyl-2-hydroxybenzoic acid, 3-isopropyl-2-hydroxybenzoic acid, 3-tert-butyl-2-hydroxybenzoic acid, 6-methoxy-2-hydroxybenzoic acid, and 6-ethoxy-2-hydroxybenzoic acid;Dihydroxy aromatic carboxylic acids such as 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2,6-dihydroxy-4-methylbenzoic acid, 2,4-dihydroxy-6-methylbenzoic acid, 3,5-dihydroxy-4-methylbenzoic acid, 2,3-dihydroxy-4-methoxybenzoic acid, 3,4-dihydroxy-5-methoxybenzoic acid, 2,4-di(hydroxymethyl)benzoic acid, and 3,4-di(hydroxymethyl)benzoic acid; trihydroxybenzoic acids such as 3,4,5-trihydroxybenzoic acid and 2,4,6-trihydroxybenzoic acid; 2-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, and 4-hydroxyphenyl Examples of the hydroxybenzoic acid include 4-hydroxybenzoic acid, 3-(2-hydroxyphenyl)propionic acid, 3-(3-hydroxyphenyl)propionic acid, 3-(4-hydroxyphenyl)propionic acid, 2-(2-hydroxyphenyl)propionic acid, 2-(3-hydroxyphenyl)propionic acid, and 2-(4-hydroxyphenyl)propionic acid. Among these, from the viewpoint of achieving both low torque and high heat resistance, preferred are one or more selected from the group consisting of 4-hydroxybenzoic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, and 3,4,5-trihydroxybenzoic acid, and more preferred are one or more selected from the group consisting of 3,5-di-tert-butyl-4-hydroxybenzoic acid and 3,4-dihydroxybenzoic acid;

[0020] The proportion of the structural moiety (B1) in the structural moiety (B) in the ester compound is preferably 0.1 mol % or more, more preferably 1 mol % or more, from the viewpoint of achieving both low torque and high heat resistance, and is preferably 5 mol % or less, more preferably 3 mol % or less, from the viewpoint of achieving both low torque and high heat resistance.

[0021] (Structural site (B2)) The structural moiety (B2) is a structural moiety derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms. From the viewpoint of achieving both low torque properties and high heat resistance, the number of carbon atoms in the structural moiety (B2) is 4 or more, preferably 7 or more, and from the viewpoint of achieving both low torque properties and high heat resistance, the number of carbon atoms in the structural moiety (B2) is 18 or less, preferably 9 or less.

[0022] Examples of the aliphatic monocarboxylic acid (B2) include straight-chain fatty acids such as butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid; 2-methylpropanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2,2-dimethylpropanoic acid, 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2,2-dimethylbutanoic acid, 2,3-dimethylbutanoic acid, 3,3-dimethylbutanoic acid, and 2-methyl Hexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 5-methylhexanoic acid, 2,2-dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 2,4-dimethylpentanoic acid, 3,3-dimethylpentanoic acid, 3,4-dimethylpentanoic acid, 4,4-dimethylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 2,2,3-trimethylbutanoic acid, 2,3,3-trimethylbutanoic acid, 2-ethyl-2-methylbutanoic acid, 2-ethyl-3-methylbutanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 4-methylheptanoic acid Hexanoic acid, 5-methylheptanoic acid, 6-methylheptanoic acid, 2-ethylhexanoic acid, 3-ethylhexanoic acid, 4-ethylhexanoic acid, 2,2-dimethylhexanoic acid, 2,3-dimethylhexanoic acid, 2,4-dimethylhexanoic acid, 2,5-dimethylhexanoic acid, 3,3-dimethylhexanoic acid, 3,4-dimethylhexanoic acid, 3,5-dimethylhexanoic acid, 4,4-dimethylhexanoic acid, 4,5-dimethylhexanoic acid, 5,5-dimethylhexanoic acid, 2-propylpentanoic acid, 2-methyloctanoic acid, 3-methyloctanoic acid, 4-methyl Octanoic acid, 5-methyloctanoic acid, 6-methyloctanoic acid, 7-methyloctanoic acid, 2,2-dimethylheptanoic acid, 2,3-dimethylheptanoic acid, 2,4-dimethylheptanoic acid, 2,5-dimethylheptanoic acid, 2,6-dimethylheptanoic acid, 3,3-dimethylheptanoic acid, 3,4-dimethylheptanoic acid, 3,5-dimethylheptanoic acid, 3,6-dimethylheptanoic acid, 4,4-dimethylheptanoic acid, 4,5-dimethylheptanoic acid, 4,6-dimethylheptanoic acid, 5,5-dimethylheptanoic acid, 5,6-dimethylheptanoic acid, 6,Examples of branched fatty acids include 6-dimethylheptanoic acid, 2-methyl-2-ethylhexanoic acid, 2-methyl-3-ethylhexanoic acid, 2-methyl-4-ethylhexanoic acid, 3-methyl-2-ethylhexanoic acid, 3-methyl-3-ethylhexanoic acid, 3-methyl-4-ethylhexanoic acid, 4-methyl-2-ethylhexanoic acid, 4-methyl-3-ethylhexanoic acid, 4-methyl-4-ethylhexanoic acid, 5-methyl-2-ethylhexanoic acid, 5-methyl-3-ethylhexanoic acid, 5-methyl-4-ethylhexanoic acid, 2-ethylheptanoic acid, 3-methyloctanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethyl-2,3,3-trimethylbutyric acid, 2,2,4,4-tetramethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, and 2,2,3,4-tetramethylpentanoic acid. Among these, from the viewpoint of achieving both low torque and high heat resistance, one or more selected from the group consisting of heptanoic acid and nonanoic acid are preferred.

[0023] The proportion of the structural moiety (B2) in the structural moiety (B) in the ester compound is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and still more preferably 97 mol% or more, from the viewpoint of achieving both low torque and high heat resistance, and is preferably 99.9 mol% or less, more preferably 99 mol% or less, from the viewpoint of achieving both low torque and high heat resistance.

[0024] The ratio of the amount of substance (mol) of the structural portion (B1) to the amount of substance (mol) of the structural portion (B2) in the structural portion (B) (amount of substance (mol) of the structural portion (B1) / amount of substance (mol) of the structural portion (B2)) is preferably 0.001 or more, more preferably 0.01 or more, from the viewpoint of achieving both low torque properties and high heat resistance, and is preferably 0.05 or less, more preferably 0.03 or less, from the viewpoint of achieving both low torque properties and high heat resistance.

[0025] The structural moiety (B) may have structural moieties other than the structural moiety (B1) and the structural moiety (B2) within the range that does not impair the effects of the present invention. The proportion of structural moieties other than the structural moiety (B1) and the structural moiety (B2) in the structural moiety (B) in the ester compound is preferably 10 mol % or less, more preferably 5 mol % or less, and even more preferably 1 mol % or less.

[0026] From the viewpoint of achieving low torque, low temperature stability, and high heat resistance at the same time, the ester compound preferably contains the following ester compound (A) and ester compound (B). Ester compound (A): R in the general formula (1) 1 ~R 4 A compound in which all hydroxyl groups of an alcohol compound (A1) are hydroxyl groups, and the aliphatic monocarboxylic acid (B2) is ester-bonded to all hydroxyl groups of the alcohol compound (A1). Ester compound (B): A compound in which the monocarboxylic acid (B1) is ester-bonded to one hydroxyl group of the alcohol compound (A1) and the aliphatic monocarboxylic acid (B2) is ester-bonded to the remaining three hydroxyl groups.

[0027] From the viewpoint of low torque, the content of the ester compound (A) in the ester compound is preferably 25% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, still more preferably 50% by mass or more, still more preferably 60% by mass or more, and still more preferably 80% by mass or more. From the viewpoint of high heat resistance, the content of the ester compound (A) in the ester compound is preferably 99% by mass or less, more preferably 98% by mass or less, even more preferably 95% by mass or less, still more preferably 92% by mass or less, and still more preferably 90% by mass or less.

[0028] From the viewpoint of high heat resistance, the content of the ester compound (B) in the ester compound is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 5% by mass or more, still more preferably 8% by mass or more, and still more preferably 10% by mass or more. From the viewpoint of low torque, the content of the ester compound (B) in the ester compound is preferably 75% by mass or less, more preferably 60% by mass or less, even more preferably 55% by mass or less, still more preferably 50% by mass or less, still more preferably 40% by mass or less, and still more preferably 20% by mass or less.

[0029] From the viewpoint of achieving low torque, low-temperature stability, and high heat resistance, the total content of the ester compound (A) and the ester compound (B) in the ester compound is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, still more preferably substantially 100% by mass, and even more preferably 100% by mass. In this specification, "substantially 100% by mass" means that substances other than the ester compound (A) and the ester compound (B) are inevitably mixed in.

[0030] The mass ratio of the ester compound (A) to the ester compound (B) in the ester compound (mass of the ester compound (A) in the ester compound / mass of the ester compound (B) in the ester compound) is preferably 1 or more, more preferably 1.5 or more, and even more preferably 2 or more from the viewpoint of low torque, and is preferably 70 or less, more preferably 60 or less, and even more preferably 50 or less from the viewpoint of high heat resistance.

[0031] From the viewpoint of achieving both low torque and high heat resistance, the content of the ester compound in the lubricating base oil is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably substantially 100% by mass, and still more preferably 100% by mass.

[0032] <Method of manufacturing lubricating base oil> The method for producing a lubricating base oil of this embodiment is a method for producing the lubricating base oil, and includes a reaction step of carrying out an esterification reaction and / or a transesterification reaction between the alcohol compound (A) and a carboxylic acid component for deriving the structural moiety (B), wherein the carboxylic acid component for deriving the structural moiety (B) contains the monocarboxylic acid (B1) and / or an ester-forming derivative of the monocarboxylic acid (B1), and the aliphatic monocarboxylic acid (B2) and / or an ester-forming derivative of the aliphatic monocarboxylic acid (B2).

[0033] Examples of the ester-forming derivatives of the monocarboxylic acid (B1) include alkyl esters having 1 to 6 carbon atoms. Examples of the ester-forming derivatives of the aliphatic monocarboxylic acid (B2) include alkyl esters of the aliphatic monocarboxylic acid (B2) having 1 to 6 carbon atoms.

[0034] The esterification reaction and transesterification reaction in the reaction step can be carried out by using known methods.

[0035] <Lubricating oil composition> The lubricating oil composition of this embodiment contains the lubricating base oil. The lubricating oil composition may contain other additives within a range that does not impair the effects of the present invention. Examples of such other additives include detergents, dispersants, antioxidants, oiliness improvers, antiwear agents, extreme pressure agents, rust inhibitors, corrosion inhibitors, metal deactivators, viscosity index improvers, pour point depressants, antifoaming agents, emulsifiers, demulsifiers, fungicides, and solid lubricants.

[0036] The content of the lubricating base oil in the lubricating oil composition is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0037] The total content of the other additives in the lubricating oil composition is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less.

[0038] The content of the ester compound (A) in the lubricating oil composition is preferably 12.5% ​​by mass or more, more preferably 25% by mass or more, even more preferably 40% by mass or more, and still more preferably 60% by mass or more, from the viewpoint of low torque. The content of the ester compound (A) in the lubricating oil composition is preferably 99% by mass or less, more preferably 98% by mass or less, even more preferably 95% by mass or less, still more preferably 92% by mass or less, and still more preferably 90% by mass or less, from the viewpoint of high heat resistance.

[0039] From the viewpoint of high heat resistance, the content of the ester compound (B) in the lubricating oil composition is preferably 0.5% by mass or more, more preferably 2% by mass or more, even more preferably 5% by mass or more, still more preferably 8% by mass or more, and even more preferably 10% by mass or more. From the viewpoint of low torque, the content of the ester compound (B) in the lubricating oil composition is preferably 75% by mass or less, more preferably 60% by mass or less, even more preferably 55% by mass or less, still more preferably 50% by mass or less, still more preferably 40% by mass or less, and even more preferably 20% by mass or less.

[0040] The lubricating oil composition can be used in combustion-based lubricating oils such as gasoline engine oils, diesel engine oils, and marine engine oils; and non-combustion-based lubricating oils such as gear oils, automatic transmission oils, hydraulic oils, fire-retardant hydraulic fluids, refrigeration oils, compressor oils, vacuum pump oils, bearing oils, insulating oils, turbine oils, sliding surface oils, rock drill oils, metal processing oils, plastic processing oils, heat treatment oils, and greases. The lubricating oil composition is particularly preferably used in the non-combustion-based lubricating oils. The lubricating oil composition can also be used in sliding parts such as rotary sliding parts like plain bearings, surface sliding parts like thrust bearings, and slide sliding parts like splines, and can be used in lubrication methods for the spline parts of clutch discs, the shaft and gear bore bearing parts of transmissions, the spline parts of hub sleeves, metal-supported parts of various parts, and the spline parts of gear shift operating systems.

[0041] In relation to the above-described embodiments, the present specification further discloses the following lubricant base oil, lubricant composition, and method for producing the lubricant base oil.

[0042] <1> The present invention comprises an ester compound having a structural moiety (A) derived from an alcohol compound (A) represented by the following general formula (1) and a structural moiety (B) derived from a carboxylic acid, The structural moiety (B) comprises a structural moiety (B1) derived from a monocarboxylic acid (B1) represented by the following general formula (2), and a structural moiety (B2) derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms: [ka] (In general formula (1), R 1 is a hydroxyl group, and R 2 From R 4 are independently a hydroxyl group, a hydrogen atom, or a saturated hydrocarbon group having 1 to 3 carbon atoms. [ka] (In general formula (2), R 5 From R 9 is a carboxyl group, -CH-COOH, or -CH-CH-COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having from 1 to 10 carbon atoms. <2> the proportion of the structural moiety (B1) in the structural moiety (B) is 0.1 mol % or more and 5 mol % or less; <1> The lubricating base oil according to claim 1. <3> the ratio of the amount of substance (mol) of the structural moiety (B1) to the amount of substance (mol) of the structural moiety (B2) in the structural moiety (B) (amount of substance (mol) of the structural moiety (B1) / amount of substance (mol) of the structural moiety (B2)) is 0.001 or more and 0.05 or less; <1> or <2> The lubricating base oil according to claim 1. <4> R in the general formula (2) 7 is a carboxyl group, <1> ~ <3> The lubricating base oil according to any one of the preceding claims. <5> The alcohol compound (A) is at least one selected from the group consisting of pentaerythritol and trimethylolpropane. <1> ~ <4> The lubricating base oil according to any one of the preceding claims. <6> The proportion of the structural moiety (B1) in the structural moiety (B) is 0.1 mol % or more and 5 mol %, and R 7 is a carboxyl group, and the alcohol compound (A) is pentaerythritol. <1> ~ <5> The lubricating base oil according to any one of the preceding claims. <7> The proportion of the structural moiety (B1) in the structural moiety (B) is 1 mol % or more and 3 mol %, and R 7 is a carboxyl group, and the alcohol compound (A) is pentaerythritol. <1> ~ <6> The lubricating base oil according to any one of the preceding claims. <8> the ratio of the amount of substance (mol) of the structural moiety (B1) to the amount of substance (mol) of the structural moiety (B2) in the structural moiety (B) is 0.001 or more and 0.05 or less, and R 7 is a carboxyl group, and the alcohol compound (A) is pentaerythritol. <1> ~ <7> The lubricating base oil according to any one of the preceding claims. <9> the ratio of the amount of substance (mol) of the structural moiety (B1) to the amount of substance (mol) of the structural moiety (B2) in the structural moiety (B) is 0.01 or more and 0.03 or less, and R 7 is a carboxyl group, and the alcohol compound (A) is pentaerythritol. <1> ~ <8> The lubricating base oil according to any one of the preceding claims. <10> the proportion of the structural moiety (B1) in the structural moiety (B) is 1 mol % or more and 3 mol %, the ratio of the amount of substance (mol) of the structural moiety (B1) to the amount of substance (mol) of the structural moiety (B2) in the structural moiety (B) is 0.01 or more and 0.03 or less, and R 7is a carboxyl group, and the alcohol compound (A) is pentaerythritol. <1> ~ <9> The lubricating base oil according to any one of the preceding claims. <11> The ester compound includes the following ester compound (A) and the following ester compound (B): <1> ~ <10> The lubricating base oil according to any one of the preceding claims. Ester compound (A): R in the general formula (1) 1 ~R 4 A compound in which all hydroxyl groups of an alcohol compound (A1) are hydroxyl groups, and the aliphatic monocarboxylic acid (B2) is ester-bonded to all hydroxyl groups of the alcohol compound (A1). Ester compound (B): A compound in which the monocarboxylic acid (B1) is ester-bonded to one hydroxyl group of the alcohol compound (A1) and the aliphatic monocarboxylic acid (B2) is ester-bonded to the remaining three hydroxyl groups. <12> The content of the ester compound (A) in the ester compound is 25% by mass or more and 99% by mass or less. <1> ~ <11> The lubricating base oil according to any one of the preceding claims. <13> The content of the ester compound (B) in the ester compound is 1% by mass or more and 75% by mass or less. <1> ~ <14> The lubricating base oil according to any one of the preceding claims. <14> the content of the ester compound (A) in the ester compound is 80% by mass or more and 99% by mass or less, and the content of the ester compound (B) in the ester compound is 1% by mass or more and 20% by mass or less; <1> ~ <13> The lubricating base oil according to any one of the preceding claims. <15> the content of the ester compound (A) in the ester compound is 80% by mass or more and 90% by mass or less, and the content of the ester compound (B) in the ester compound is 1% by mass or more and 10% by mass or less; <1> ~ <14> The lubricating base oil according to any one of the preceding claims. <16> the total content of the ester compound (A) and the ester compound (B) in the ester compound is 80 mass% or more; <1> ~ <15> The lubricating base oil according to any one of the preceding claims. <17> a mass ratio of the ester compound (A) to the ester compound (B) in the ester compound (mass of the ester compound (A) in the ester compound / mass of the ester compound (B) in the ester compound) is 1 or more and 70 or less; <1> ~ <16> The lubricating base oil according to any one of the preceding claims. <18> the content of the ester compound (A) in the ester compound is 80% by mass or more and 99% by mass or less, the content of the ester compound (B) is 1% by mass or more and 20% by mass or less, and the mass ratio of the ester compound (A) to the ester compound (B) in the ester compound is 1.5 or more and 60 or less; <1> ~ <17> The lubricating base oil according to any one of the preceding claims. <19> 1. The lubricating base oil according to claim 1, wherein the content of the ester compound (A) in the ester compound is 80% by mass or more and 90% by mass or less, the content of the ester compound (B) in the ester compound is 10% by mass or more and 20% by mass or less, and the mass ratio of the ester compound (A) to the ester compound (B) in the ester compound is 2 or more and 50 or less. <20> <1> ~ <19> A lubricating oil composition comprising the lubricating base oil according to any one of the preceding claims. <21> The content of the lubricating base oil in the lubricating oil composition is 50% by mass or more. <20> The lubricating oil composition according to claim 1. <22> The content of the ester compound (A) in the lubricating oil composition is 12.5% ​​by mass or more and 99% by mass or less. <20> or <21> The lubricating oil composition according to claim 1. <23> The content of the ester compound (B) in the lubricating oil composition is 0.5% by mass or more and 75% by mass or less. <20> ~ <22> The lubricating base oil according to any one of the preceding claims. <24> the content of the ester compound (A) in the lubricating oil composition is 40% by mass or more and 98% by mass or less, and the content of the ester compound (B) in the lubricating oil composition is 2% by mass or more and 60% by mass or less; <20> ~ <23> The lubricating base oil according to any one of the preceding claims. <25> the content of the ester compound (A) in the lubricating oil composition is 60% by mass or more and 95% by mass or less, and the content of the ester compound (B) in the lubricating oil composition is 5% by mass or more and 40% by mass or less; <20> ~ <24> The lubricating base oil according to any one of the preceding claims. <26> The present invention comprises an ester compound having a structural moiety (A) derived from an alcohol compound (A) represented by the following general formula (1) and a structural moiety (B) derived from a carboxylic acid, A method for using an ester compound, in a lubricating base oil, in which the structural moiety (B) includes a structural moiety (B1) derived from a monocarboxylic acid (B1) represented by the following general formula (2) and a structural moiety (B2) derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms: [ka] (In general formula (1), R 1 is a hydroxyl group, and R 2 From R 4 are independently a hydroxyl group, a hydrogen atom, or a saturated hydrocarbon group having 1 to 3 carbon atoms. [ka] (In general formula (2), R 5 From R 9 is a carboxyl group, -CH-COOH, or -CH-CH-COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having from 1 to 10 carbon atoms. [Example]

[0043] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0044] <Preparation of lubricating base oil> Example 1 A 1-liter four-neck flask equipped with a stirrer, thermometer, nitrogen inlet, and condenser was charged with 453.30 g of heptanoic acid and 11.0 g of 3,5-di-tert-butyl-4-hydroxybenzoic acid as monocarboxylic acids, and 150.1 g of pentaerythritol as alcohol. The amounts of monocarboxylic acids were adjusted so that the total carboxyl groups of the monocarboxylic acids was 0.8 equivalents per equivalent of hydroxyl groups of the alcohol. Next, nitrogen gas was blown into the flask, and the temperature was raised to 250°C while stirring. The flask was maintained at 250°C for 4 hours, and the distilled water was removed from the flask using the condenser. After the reaction was completed, an additional 230.04 g of heptanoic acid was added. The temperature was again raised to 250°C. The flask was maintained at 250°C for 10 hours, and the distilled water was removed from the flask using the condenser. After the reaction was completed, excess carboxylic acid components were distilled off under a reduced pressure of 0.13 kPa, and the mixture was steamed for 1 hour under a reduced pressure of 0.13 kPa. The remaining carboxylic acid components were adsorbed onto an adsorbent (trade name: Kyoward 500SH, manufactured by Kyowa Chemical Industry Co., Ltd.), and the reaction product in the flask was filtered to obtain lubricating base oil 1 according to Example 1.

[0045] [Examples 2, 3, 5, 6, and 8, and Comparative Examples 1 and 2] Each lubricating base oil was obtained in the same manner as in Example 1, except that the types and blending amounts of each raw material were changed as shown in Table 1.

[0046] Example 4 A 1-liter four-neck flask equipped with a stirrer, thermometer, nitrogen inlet, and condenser was charged with 305.10 g of heptanoic acid and 160.0 g of 3,5-di-tert-butyl-4-hydroxybenzoic acid as monocarboxylic acids, 145.1 g of pentaerythritol as alcohol, and 0.26 g of titanium tetraisopropoxide as catalyst. The monocarboxylic acids were mixed in such a way that the total carboxyl groups of the monocarboxylic acids were 0.8 equivalents per equivalent of hydroxyl groups of the alcohol. Next, nitrogen gas was blown into the flask, and the temperature was raised to 250°C while stirring. The flask was maintained at 250°C for 4 hours, and the distilled water was removed from the flask using the condenser. After the reaction was completed, an additional 247.0 g of heptanoic acid was added. The temperature was again raised to 250°C. The flask was maintained at 250°C for 10 hours, and the distilled water was removed from the flask using the condenser. After the reaction was completed, 17.3 g of ion-exchanged water was added, and the mixture was stirred at 80 ° C for 1 hour to deactivate the catalyst. Then, water and excess carboxylic acid components were distilled off under a reduced pressure of 0.13 kPa, and steaming was performed for 1 hour under a reduced pressure of 0.13 kPa. After the remaining carboxylic acid components were adsorbed onto an adsorbent (trade name: Kyoward 500SH, manufactured by Kyowa Chemical Industry Co., Ltd.), the reaction product in the flask was filtered to obtain lubricating base oil 4 according to Example 4.

[0047] Example 7 The lubricating base oil of Example 7 was obtained in the same manner as in Example 4, except that the types and blending amounts of each raw material were changed as shown in Table 1.

[0048] Comparative Example 3 An ester compound according to Comparative Example 3 was obtained in the same manner as in Example 1, except that the types and blending amounts of each raw material were changed as shown in Table 1. An additive (IRGANOX 1076 (manufactured by BASF)) was added to the ester compound so that the content in the lubricating base oil was 1.6 mass %, thereby obtaining a lubricating base oil according to Comparative Example 3.

[0049] The amounts of raw materials used in the synthesis of the above-mentioned Examples and Comparative Examples are shown in Table 1. The raw materials listed in Tables 1 and 2 (described later) are as follows. Trimethylolpropane (Tokyo Chemical Industry Co., Ltd.) Pentaerythritol (Tokyo Chemical Industry Co., Ltd.) Heptanoic acid (n-heptanoic acid, manufactured by Tokyo Chemical Industry Co., Ltd.) Nonanoic acid (Tokyo Chemical Industry Co., Ltd.) 3,5-Di-tert-butyl-4-hydroxybenzoic acid (Tokyo Chemical Industry Co., Ltd.) 4-Hydroxybenzoic acid (Fujifilm Wako Pure Chemical Industries, Ltd.) 3,4-Dihydroxybenzoic acid (Fujifilm Wako Pure Chemical Industries, Ltd.) Titanium tetraisopropoxide (Fujifilm Wako Pure Chemical Industries, Ltd.) Methyl gallate (Tokyo Chemical Industry Co., Ltd.) Benzoic acid (Fujifilm Wako Pure Chemical Industries, Ltd.) IRGANOX1076 (BASF)

[0050] [Table 1]

[0051] <Evaluation> [Composition of ester compound] The composition of the ester compounds contained in each of the lubricating base oils according to Examples 1 to 8 and Comparative Examples 1 to 3 was measured by the method shown below. The ester compound was dissolved in deuterated acetone and analyzed using a nuclear magnetic resonance apparatus (trade name: Agilent 400-MR DD2 system, manufactured by Agilent Technologies, Inc.). 1 H-NMR measurement was performed. Since the proton intensity is proportional to the number of moles, the molar ratio of the number of ester groups having an alkyl chain or a phenol structure was calculated from the ratio of the proton intensity of each peak obtained by the measurement. Alkyl chain: Calculation was made based on the peak that appears around 2.3 ppm and is derived from the methylene group at the α-position of the alkyl chain. Phenol structure: Calculated based on the peaks derived from the methine hydrogens at the 2nd and 6th positions of the aromatic ring, which appear around 8.0 ppm. The compositions of the ester compounds contained in the lubricating base oils according to Examples 1 to 8 and Comparative Examples 1 to 3 obtained by the measurements are shown in Table 2.

[0052] [Table 2]

[0053] [Evaluation of low torque] The kinematic viscosity of each lubricating base oil in each example and comparative example was measured at 40°C and 100°C (mm 2 The lower the viscosity, the better the low torque.

[0054] [Evaluation of high heat resistance] The high heat resistance of each lubricating base oil according to each example and comparative example was evaluated by measuring the thermal response of each lubricating base oil using a simultaneous thermogravimetry and differential thermal analyzer (product name: TG / DTA6200, manufactured by Seiko Instruments Inc.) under conditions of a nitrogen and air atmosphere of 200 mL / min, heating from 30°C to 500°C at 10°C / min, and then holding the temperature at 500°C for 3 minutes, and comparing the temperature at which the weight loss rate (mass%) reached 10%. A higher temperature indicates better heat resistance.

[0055] [Evaluation of low temperature stability (pour point)] The pour point of each lubricating base oil according to each example and comparative example was evaluated by measuring the pour point (°C) using a measurement method in accordance with JIS K 2269. A lower pour point indicates better low-temperature stability.

[0056] [Evaluation of low temperature stability (appearance)] The low-temperature stability of each lubricating base oil according to each example and comparative example was evaluated by placing a 10 mL sample in a screw tube (No. 5), storing it at -20°C in a low-temperature incubator PU-1KP (manufactured by ESPEC) for 1 day, and then evaluating its appearance (liquid / solid).

[0057] The results of the evaluation are shown in Table 3.

[0058] [Table 3]

[0059] The results in Table 3 show that the lubricating base oils according to Examples 1 to 8 are excellent in low torque properties, low temperature stability, and high heat resistance.

Claims

1. The present invention comprises an ester compound having a structural moiety (A) derived from an alcohol compound (A) represented by the following general formula (1) and a structural moiety (B) derived from a carboxylic acid, the structural moiety (B) includes a structural moiety (B1) derived from a monocarboxylic acid (B1) represented by the following general formula (2), and a structural moiety (B2) derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms, the proportion of the structural moiety (B1) in the structural moiety (B) is 0.1 mol % or more, the proportion of the structural moiety (B2) in the structural moiety (B) is 80 mol % or more; A lubricating base oil, wherein the ratio of the amount of substance (mol) of the structural moiety (B1) to the amount of substance (mol) of the structural moiety (B2) in the structural moiety (B) (amount of substance (mol) of the structural moiety (B1) / amount of substance (mol) of the structural moiety (B2)) is 0.05 or less. 【Chemistry 1】 (In general formula (1), R １ is a hydroxyl group, and R ２ From R ４ are independently a hydroxyl group, a hydrogen atom, or a saturated hydrocarbon group having 1 to 3 carbon atoms. 【Chemistry 2】 (In general formula (2), R ５ From R ９ Any one of the following is a carboxyl group, -CH ２ -COOH or -CH ２ -CH ２ -COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having 1 to 10 carbon atoms.

2. The lubricating base oil according to claim 1, wherein the proportion of the structural moiety (B1) in the structural moiety (B) is 5 mol % or less.

3. The ratio of the amount of substance (mol) of the structural moiety (B1) to the amount of substance (mol) of the structural moiety (B2) in the structural moiety (B) (amount of substance (mol) of the structural moiety (B1) / amount of substance (mol) of the structural moiety (B2)) is 0.001 or more. The lubricating base oil according to claim 1 or 2.

4. R in the general formula (2) ７ The lubricating base oil according to any one of claims 1 to 3, wherein is a carboxyl group.

5. The lubricating base oil according to any one of claims 1 to 4, wherein the alcohol compound (A) is at least one selected from the group consisting of pentaerythritol and trimethylolpropane.

6. The lubricating base oil according to any one of claims 1 to 5, wherein the ester compounds comprise the following ester compound (A) and the following ester compound (B): Ester compound (A): R in the general formula (1) １ ~R ４ a compound in which all hydroxyl groups of an alcohol compound (A1) are hydroxyl groups, and the aliphatic monocarboxylic acid (B2) is ester-bonded to all hydroxyl groups of the alcohol compound (A1) Ester compound (B): A compound in which the monocarboxylic acid (B1) is ester-bonded to one hydroxyl group of the alcohol compound (A1) and the aliphatic monocarboxylic acid (B2) is ester-bonded to the remaining three hydroxyl groups.

7. The lubricating base oil according to claim 6, wherein the content of the ester compound (A) in the ester compound is 25% by mass or more and 99% by mass or less.

8. The lubricating base oil according to claim 6 or 7, wherein the content of the ester compound (B) in the ester compound is 1% by mass or more and 75% by mass or less.

9. The lubricating base oil according to any one of claims 6 to 8, wherein the total content of the ester compound (A) and the ester compound (B) in the ester compound is 80% by mass or more.

10. The lubricating base oil according to any one of claims 6 to 9, wherein the mass ratio of the ester compound (A) to the ester compound (B) in the ester compound (mass of the ester compound (A) in the ester compound / mass of the ester compound (B) in the ester compound) is 1 or more and 70 or less.

11. A lubricating oil composition comprising the lubricating base oil according to any one of claims 1 to 10.

12. The content of the lubricating base oil in the lubricating oil composition is 50 mass % or more. The lubricating oil composition of claim 11.

13. The method for producing the lubricating base oil according to any one of claims 1 to 10, a reaction step of carrying out an esterification reaction and / or a transesterification reaction between the alcohol compound (A) and a carboxylic acid component for deriving the structural moiety (B), a carboxylic acid component for deriving the structural moiety (B) comprising the monocarboxylic acid (B1) and / or an ester-forming derivative of the monocarboxylic acid (B1), and the aliphatic monocarboxylic acid (B2) and / or an ester-forming derivative of the aliphatic monocarboxylic acid (B2).

14. The present invention comprises an ester compound having a structural moiety (A) derived from an alcohol compound (A) represented by the following general formula (1) and a structural moiety (B) derived from a carboxylic acid, the structural moiety (B) includes a structural moiety (B1) derived from a monocarboxylic acid (B1) represented by the following general formula (2), and a structural moiety (B2) derived from an aliphatic monocarboxylic acid (B2) having from 4 to 18 carbon atoms, the proportion of the structural moiety (B1) in the structural moiety (B) is 0.1 mol % or more, the proportion of the structural moiety (B2) in the structural moiety (B) is 80 mol % or more; A method for using an ester compound in a lubricating base oil, wherein the ratio of the amount of substance (mol) of the structural moiety (B1) to the amount of substance (mol) of the structural moiety (B2) in the structural moiety (B) (amount of substance (mol) of the structural moiety (B1) / amount of substance (mol) of the structural moiety (B2)) is 0.05 or less. 【Transformation 3】 (In general formula (1), R １ is a hydroxyl group, and R ２ From R ４ are independently a hydroxyl group, a hydrogen atom, or a saturated hydrocarbon group having 1 to 3 carbon atoms. 【Chemistry 4】 (In general formula (2), R ５ From R ９ Any one of the following is a carboxyl group, -CH ２ -COOH or -CH ２ -CH ２ -COOH, and the others are each independently a hydrogen atom, a hydroxyl group, or a saturated hydrocarbon group having 1 to 10 carbon atoms.

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