Power transmission lubricant base oil

Abstract

To provide a lubricant base oil for power transmission that is high in traction coefficient and flash point and is superior in low temperature flowability.SOLUTION: The present invention relates to a lubricant base oil for power transmission that comprises an ester compound represented by the following general formula (1) [where R1-R5 are the same or different to represent a hydrogen atom or a C1-4 linear or branched alkyl group].SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a lubricant base oil for power transmissions, and more particularly to a lubricant base oil for traction drives. [Background technology]

[0002] In recent years, with the advancement of the digital information society, the precision required for printers and copiers is increasing. In particular, high rotational precision, low vibration and low noise are required for the motor section, which is required for highly accurate paper feeding. When a gear system is used as the power transmission means for these rotating parts, vibration and noise are large, so a traction drive that reduces these is often used.

[0003] In addition, with the spread of industrial robots, traction drives are also used in joints that require precise movements. Other applications of traction drives include continuously variable transmissions for industrial equipment, aircraft generators, and rotor speed control for helicopters. In order to increase the amount of power transmitted, studies have been conducted on making the traction drives larger, but there is a tendency for the amount of heat generated to increase with the increase in contact area.

[0004] Lubricant base oils for traction drives preferably have a high traction coefficient to enhance power transmission performance, and alicyclic hydrocarbon compounds have been proposed, such as dicyclohexyl compounds represented by 2-methyl-2,4-dicyclohexylpentane and dimerized norbornanes (Patent Documents 1 and 2).

[0005] However, alicyclic hydrocarbon compounds such as 2-methyl-2,4-dicyclohexylpentane tend to have low flash points of 200°C or less, which is not necessarily sufficient for use in fields where heat resistance and safety are important, such as large traction drives.

[0006] Ester compounds have also been proposed as lubricant base oils for traction drives with high flash points, such as alicyclic diester compounds typified by di(cyclohexylmethyl) 1,2-cyclohexanedicarboxylate (Patent Document 3).

[0007] However, alicyclic diester compounds, such as di(cyclohexylmethyl) 1,2-cyclohexanedicarboxylate, tend to have high pour points of -20°C or higher, which are not necessarily sufficient for use in aircraft, helicopters, automobiles, and other fields where operability at low temperatures is important. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 47-7664 [Patent Document 2] Japanese Patent Application Publication No. 3-95295 [Patent Document 3] International Publication No. 2018 / 008667 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a lubricating base oil for power transmission (particularly a lubricating base oil for traction drives) having a high traction coefficient, a high flash point and good low-temperature fluidity. [Means for solving the problem]

[0010] The present inventors have found that a specific ester compound has a high traction coefficient and a flash point, and also has good low-temperature fluidity. The present invention was completed through further investigation based on this finding.

[0011] That is, the present invention provides a power transmission lubricant base oil (particularly, a traction drive lubricant base oil) that satisfies the following requirements:

[0012] [Section 1] General formula (1) [ka] [In the formula, R 1 ~R 5 are the same or different and each represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms.] The present invention relates to a power transmission lubricating base oil containing an ester compound represented by the formula:

[0013] [Section 2] R in the general formula (1) 1 ~R 5 are the same or different and each is a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a tert-butyl group.

[0014] [Section 3] R in the general formula (1) 1 ~R 5 are the same or different and each is a hydrogen atom or a methyl group.

[0015] [Section 4] The power transmission lubricant base oil according to any one of [Item 1] to [Item 3], wherein the content of the ester compound represented by general formula (1) in the power transmission lubricant base oil is 70 mass % or more.

[0016] [Section 5] The power transmission lubricant base oil according to any one of [Item 1] to [Item 3], wherein the content of the ester compound represented by general formula (1) in the power transmission lubricant base oil is 90 mass % or more.

[0017] [Section 6] The power transmission lubricant base oil according to any one of [Item 1] to [Item 5], wherein the power transmission lubricant base oil is a traction drive lubricant base oil.

[0018] [Section 7] A lubricant for power transmission comprising the lubricant base oil for power transmission according to any one of [Item 1] to [Item 6].

[0019] [Section 8] A lubricating oil for power transmission, comprising the lubricating oil base oil for power transmission according to any one of [Item 1] to [Item 6] and an antioxidant.

[0020] [Section 9] Item 8. The lubricating oil for power transmission according to item 8, wherein the antioxidant is a phenol-based antioxidant and / or an amine-based antioxidant. Effect of the Invention

[0021] The ester compound of the present invention has the characteristics of having a high traction coefficient (60°C, 140°C) and flash point, and good low-temperature fluidity, and can therefore be suitably used as a lubricant base oil for power transmission (particularly, a lubricant base oil for traction drives). [Brief description of the drawings]

[0022] [Figure 1] 1 is an IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2-methyl-cyclohexanecarboxylate obtained in Example 1. [Diagram 2] 1H-NMR spectrum of 2-methyl-cyclohexanecarboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl obtained in Example 1. [Diagram 3] IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3-methyl-cyclohexanecarboxylate obtained in Example 2. [Figure 4] 1H-NMR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3-methyl-cyclohexanecarboxylate obtained in Example 2. [Diagram 5]IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 4-methyl-cyclohexanecarboxylate obtained in Example 3. [Figure 6] 1H-NMR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 4-methyl-cyclohexanecarboxylate obtained in Example 3. [Figure 7] IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3,5-dimethyl-cyclohexanecarboxylate obtained in Example 4. [Figure 8] 1H-NMR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3,5-dimethyl-cyclohexanecarboxylate obtained in Example 4. [Figure 9] 1 is an IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl cyclohexanecarboxylate obtained in Example 5. [Figure 10] 1H-NMR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl cyclohexanecarboxylate obtained in Example 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The power transmission lubricating base oil of the present invention is represented by the general formula (1) [ka] [In the formula, R 1 ~R 5 are the same or different and each represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms.] The present invention is characterized in that it contains an ester compound represented by the following formula:

[0024] R in the general formula (1) 1 ~R 5are preferably the same or different and each is a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a tert-butyl group.

[0025] Specific examples of the ester compound represented by the general formula (1) include 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl cyclohexane carboxylate, 2-methylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2-methylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3-methylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 4-methylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2-methylcyclohexane carboxylate, ,3-Dimethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 2,4-Dimethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 2,5-Dimethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 2,6-Dimethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 3,4-Dimethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3,5-dimethylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2,3,4-trimethylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2,3,5-trimethylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2,3,6-trimethylcyclohexane carboxylate, 2-(1,3,3 -trimethylbutyl)-5,7,7-trimethyl-1-octyl, 2,4,5-trimethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 2,4,6-trimethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 3,4,5-trimethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 2-ethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 3-ethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 4-ethylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 2-isopropylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl, 3-isopropylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl) 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 4-isopropylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2-tert-butylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3-tert-butylcyclohexane carboxylate, 4-tert-butylcyclohexane carboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl is preferred, and in particular, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl cyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2-methylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3-methylcyclohexane carboxylate, 4-methylcyclohexane carboxylate, Preferred are 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl cyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3,4-dimethylcyclohexane carboxylate, 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3,5-dimethylcyclohexane carboxylate, and 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 4-tert-butylcyclohexane carboxylate.

[0026] The above ester compounds can be used alone or in combination as a mixture of two or more types as a lubricating oil base oil for power transmission.

[0027] The method for producing the ester compound represented by the general formula (1) is not particularly limited. For example, the ester compound represented by the general formula (1) can be produced by reacting (esterification reaction or transesterification reaction) the alcohol represented by the formula (2) with the carboxylic acid compound represented by the general formula (3) or a derivative thereof, as shown in reaction formula 1. Here, examples of the derivative of the carboxylic acid represented by the general formula (3) include highly reactive derivatives such as acid halides (e.g., acid chlorides, etc.), mixed acid anhydrides, and active esters, and lower (1 to 4 carbon atoms) alkyl esters. [ka] [In the formula, R 1 ~R 5 Same as above.] The ester compound represented by the general formula (1) can be produced, for example, by dehydration condensation of an alcohol represented by the formula (2) and a carboxylic acid compound represented by the general formula (3) in the presence of an acid catalyst (e.g., sulfuric acid, p-toluenesulfonic acid, etc.) while removing by-produced water by heating. It can also be produced by a similar method by changing the acid catalyst to an inorganic metal catalyst (e.g., tin oxide, etc.) or an organic titanium catalyst (e.g., tetra-n-butoxytitanium, etc.). In addition, the ester compound represented by general formula (1) can also be produced by reacting an alcohol represented by formula (2) with a carboxylic acid compound represented by general formula (3) in the presence of a condensing agent (e.g., dicyclohexylcarbodiimide, carbonyldiimidazole, etc.). Alternatively, the ester compound represented by general formula (1) can be produced by converting the carboxylic acid compound represented by general formula (3) into a highly reactive derivative such as an acid halide (e.g., an acid chloride), a mixed acid anhydride, or an activated ester, and then reacting the resulting derivative with an alcohol represented by formula (2) in the presence of a base (e.g., triethylamine, 4-(N,N-dimethylamino)pyridine, pyridine, etc.). Furthermore, the ester compound represented by the general formula (1) can also be produced by reacting (esterifying) the carboxylic acid compound represented by the general formula (3) with a lower (carbon number 1 to 4) alcohol (e.g., methanol, ethanol, etc.) to form a lower alkyl ester, and then subjecting the lower alkyl ester to a transesterification reaction with the alcohol represented by the formula (2). The reaction shown in the above reaction scheme 1 can be carried out according to or in accordance with known reaction conditions depending on the type of reaction.

[0028] Alternatively, the ester compound represented by general formula (1) can be produced by reacting (esterification reaction or transesterification reaction) an alcohol represented by formula (2) with an aromatic carboxylic acid or a derivative thereof represented by general formula (4) to obtain a compound represented by general formula (5), and then hydrogenating (reducing) the aromatic ring of the compound, as shown in reaction formula 2. Here, examples of the derivative of the aromatic carboxylic acid represented by general formula (4) include highly reactive derivatives such as acid halides (e.g., acid chlorides, etc.), mixed acid anhydrides, and active esters, and lower (1 to 4 carbon atoms) alkyl esters. [ka] [In the formula, R 1 ~R 5 Same as above.] The reaction of producing a compound represented by general formula (5) by reacting an alcohol represented by formula (2) with an aromatic carboxylic acid represented by general formula (4) or a derivative thereof can be carried out according to or in accordance with the reaction of producing a compound represented by general formula (1) by reacting an alcohol represented by formula (2) with a carboxylic acid compound represented by general formula (3) or a derivative thereof in the above reaction scheme 1. A known method can be adopted for the reaction of hydrogenating (reducing) the compound represented by the general formula (5). For example, the compound represented by the general formula (1) can be produced by reducing the compound represented by the general formula (5) under a hydrogen atmosphere (from room temperature to pressure) in the presence of a reduction catalyst (a transition metal such as platinum, palladium, nickel, or rhodium, or an oxide thereof, palladium / C, etc.).

[0029] The acid value of the ester compound represented by the general formula (1) is preferably 0.1 mgKOH / g or less, more preferably 0.05 mgKOH / g or less. When the acid value is 0.1 mgKOH / g or less, the heat resistance of the ester compound represented by the general formula (1) itself tends to be improved, which has a favorable effect on the improvement of the thermal oxidation stability of the base oil of the present invention. Examples of methods for reducing the acid value include a method of allowing the reaction to proceed sufficiently, a method of neutralizing with an alkaline component in a post-treatment process and washing with water (for example, a method of washing (neutralizing) with an aqueous alkaline solution and washing with water), and a method of adsorption treatment with activated alumina.

[0030] The hydroxyl value of the ester compound represented by general formula (1) is preferably 2 mgKOH / g or less, more preferably 1 mgKOH / g or less. When the hydroxyl value is 2 mgKOH / g or less, the hygroscopicity of the ester compound represented by general formula (1) itself tends to be lower and the heat resistance tends to be improved, which has a favorable effect on the improvement of the water resistance and thermo-oxidation stability of the base oil of the present invention. Examples of methods for reducing the hydroxyl value include a method of allowing the reaction to proceed sufficiently and a method of distilling off the raw material alcohol component in the post-treatment step under reduced pressure (for example, a method of distilling off the excess raw material alcohol that can be distilled under reduced pressure or normal pressure).

[0031] The present invention discloses a power transmission lubricant base oil (particularly, a traction drive lubricant base oil) containing a diester compound represented by general formula (1).

[0032] The traction coefficient (60°C) of the power transmission lubricating base oil is usually 0.080 or more, and preferably 0.090 or more. In this specification and claims, the traction coefficient (60°C) is a value measured by the method described in the Examples below.

[0033] The traction coefficient (140°C) is usually 0.075 or more, and preferably 0.085 or more. In this specification and claims, the traction coefficient (140°C) is a value measured by the method described in the Examples below.

[0034] The low-temperature fluidity of the power transmission lubricant base oil can be evaluated, for example, by the pour point. From the viewpoint of low-temperature operability, the pour point of the lubricant base oil is usually -30°C or less, preferably -35°C or less. In this specification and claims, the pour point is a value measured by the method described in the examples below.

[0035] The flash point of the lubricating oil base oil for power transmission is usually 185° C. or higher, preferably 200° C. or higher, from the viewpoint of storage stability and handling. If it is less than 185° C., restrictions on handling due to ignition increase. In this specification and claims, the flash point is a value measured by the method described in the examples below.

[0036] Examples of the lubricating base oil for power transmission include lubricating base oil for power transmission having a traction coefficient (60°C) of 0.090 or more, a traction coefficient (140°C) of 0.085 or more, a pour point of -30°C or less, and a flash point of 185°C or more; lubricating base oil for power transmission having a traction coefficient (60°C) of 0.090 or more, a traction coefficient (140°C) of 0.075 or more, a pour point of -35°C or less, and a flash point of 185°C or more; lubricating base oil for power transmission having a traction coefficient (60°C) of 0.090 or more, a traction coefficient (140°C) of 0.075 or more, a pour point of -30°C or less, and a flash point of 200°C or more; and lubricating base oil for power transmission having a traction coefficient (60°C) of 0.080 or more, a traction coefficient (140°C) of 0.075 or more, a pour point of -35°C or less, and a flash point of 200°C or more. Further, lubricating base oils for power transmission having a traction coefficient (60°C) of 0.090 or more, a traction coefficient (140°C) of 0.085 or more, a pour point of -35°C or less, and a flash point of 185°C or more are preferred; lubricating base oils for power transmission having a traction coefficient (60°C) of 0.090 or more, a traction coefficient (140°C) of 0.085 or more, a pour point of -30°C or less, and a flash point of 200°C or more; and lubricating base oils for power transmission having a traction coefficient (60°C) of 0.090 or more, a traction coefficient (140°C) of 0.075 or more, a pour point of -35°C or less, and a flash point of 200°C or more are preferred, and lubricating base oils for power transmission having a traction coefficient (60°C) of 0.090 or more, a traction coefficient (140°C) of 0.085 or more, a pour point of -35°C or less, and a flash point of 200°C or more are particularly preferred.

[0037] The lubricating oil base oil for power transmission of the present invention has a high traction coefficient (60°C, 140°C) and flash point, and has good low-temperature fluidity, and is therefore suitable for use as a lubricating oil base oil for power transmission, particularly as a lubricating oil base oil for traction drives.

[0038] The power transmission lubricant base oil of the present invention may contain other base oils that can be used in combination (hereinafter referred to as "combined base oils"). In other words, the power transmission lubricant base oil of the present invention includes only the ester compound represented by the general formula (1) and a mixture of the ester compound represented by the general formula (1) and the combined base oil. Hereinafter, the power transmission lubricant base oil may be referred to as "base oil".

[0039] Examples of base oils that can be used in combination include mineral oils (hydrocarbon oils obtained by refining petroleum), poly-α-olefins, polybutenes, alkylbenzenes, alkylnaphthalenes, alicyclic hydrocarbon oils, animal and vegetable oils, organic acid esters (excluding the ester compounds represented by general formula (1)), polyalkylene glycols, polyvinyl ethers, polyphenyl ethers, alkylphenyl ethers, silicone oils, etc. At least one of these can be used in combination as appropriate.

[0040] Examples of mineral oils include solvent refined mineral oils, hydrorefined mineral oils, and wax isomerized oils. Generally, the kinetic viscosity at 100°C is 1 to 25 mm 2 / s, preferably 2 to 20 mm 2 The range of / s is used.

[0041] The poly-α-olefin is a polymer or copolymer of an α-olefin having 2 to 16 carbon atoms (e.g., ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, etc.) and has a kinetic viscosity of 1 to 25 mm at 100°C. 2 Examples of such oils include oils with a kinematic viscosity of 1.5 to 20 mm / s and a viscosity index of 100 or more. 2 / s and a viscosity index of 120 or more is preferred.

[0042] Polybutene includes isobutylene polymerized and isobutylene copolymerized with normal butylene, and generally has a kinetic viscosity of 2 to 40 mm at 100°C. 2 / s wide range.

[0043] Examples of alkylbenzenes include monoalkylbenzenes, dialkylbenzenes, trialkylbenzenes, tetraalkylbenzenes, and the like, which are substituted with a linear or branched alkyl group having 1 to 40 carbon atoms and have a molecular weight of 200 to 450.

[0044] Examples of alkylnaphthalene include monoalkylnaphthalene and dialkylnaphthalene substituted with a straight-chain or branched alkyl group having 1 to 30 carbon atoms.

[0045] Alicyclic hydrocarbon oils include naphthenic hydrocarbon oils, and generally have a kinetic viscosity at 100°C of 1 to 40 mm 2 Examples include a wide range of / s.

[0046] Examples of animal and vegetable oils include beef tallow, lard, palm oil, coconut oil, rapeseed oil, castor oil, sunflower oil, and the like.

[0047] Examples of organic acid esters include fatty acid monoesters (excluding the ester compounds represented by the general formula (1)), aliphatic dibasic acid diesters, aliphatic dihydric alcohol diesters, polyol esters, and other esters.

[0048] Examples of fatty acid monoesters include esters of aliphatic linear or branched monocarboxylic acids having 5 to 22 carbon atoms and linear or branched saturated or unsaturated aliphatic alcohols having 3 to 22 carbon atoms, except for the ester compounds represented by the general formula (1).

[0049] Examples of the aliphatic dibasic acid diester include diesters of aliphatic dibasic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonamethylenedicarboxylic acid, and 1,10-decamethylenedicarboxylic acid, or anhydrides thereof, and linear or branched, saturated or unsaturated aliphatic alcohols having 3 to 22 carbon atoms.

[0050] Examples of aliphatic dihydric alcohol diesters and polyol esters include neopentyl type structure polyols such as neopentyl glycol, 2,2-diethylpropanediol, 2-butyl 2-ethylpropanediol, trimethylolethane, trimethylolpropane, pentaerythritol, ditrimethylolpropane, and dipentaerythritol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1, 6-Hexanediol, 1,7-Heptanediol, 1,8-Octanediol, 1,9-Nonanediol, 1,10-Decanediol, 1,2-Propanediol, 2-Methyl-1,3-Propanediol, 1,3-Butanediol, 2-Methyl-1,4-Butanediol, 1,4-Pentanediol, 2-Methyl-1,5-Pentanediol, 3-Methyl-1,5-Pentanediol, 1,5-Hexanediol, 2-Methyl-1 ,6-Hexanediol, 3-Methyl-1,6-Hexanediol, 1,6-Heptanediol, 2-Methyl-1,7-Heptanediol, 3-Methyl-1,7-Heptanediol, 4-Methyl-1,7-Heptanediol, 1,7-Octanediol, 2-Methyl-1,8-Octanediol, 3-Methyl-1,8-Octanediol, 4-Methyl-1,8-Octanediol, 1,8-Nonanediol, 2-Methyl-1,9-Nonadiol It is possible to use full esters of polyols having a non-neopentyl structure, such as hexanediol, 3-methyl-1,9-nonanediol, 4-methyl-1,9-nonanediol, 5-methyl-1,9-nonanediol, 2-ethyl-1,3-hexanediol, 2,4-diethyl-1,5-pentanediol, glycerin, polyglycerin, sorbitol, and linear and / or branched, saturated or unsaturated fatty acids having 3 to 22 carbon atoms.

[0051] Other examples of the ester include esters of polymerized fatty acids such as dimer acid and hydrogenated dimer acid, or hydroxy fatty acids such as condensed castor oil fatty acid and hydrogenated condensed castor oil fatty acid, and linear or branched, saturated or unsaturated aliphatic alcohols having 3 to 22 carbon atoms.

[0052] Examples of polyalkylene glycols include ring-opening polymers of alcohols and linear or branched alkylene oxides having 2 to 4 carbon atoms. Examples of alkylene oxides include ethylene oxide, propylene oxide, and butylene oxide, and polymers using one of these or copolymers using a mixture of two or more of these can be used. Compounds in which the hydroxyl groups at one or both ends are etherified can also be used. The kinetic viscosity of the polymer is preferably 5 to 1000 mm 2 / s (40°C), more preferably 5 to 500 mm 2 / s(40℃) is recommended.

[0053] Polyvinyl ether is a compound obtained by polymerization of vinyl ether monomers, and examples of the monomers include methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, sec-butyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl ether, n-hexyl vinyl ether, 2-methoxyethyl vinyl ether, 2-ethoxyethyl vinyl ether, etc. The kinetic viscosity of the polymer is preferably 5 to 1000 mm 2 / s (40°C), more preferably 5 to 500 mm 2 / s(40℃) is recommended.

[0054] Examples of polyphenyl ethers include compounds having a structure in which the meta positions of two or more aromatic rings are linked by an ether bond or a thioether bond. Specific examples include bis(m-phenoxyphenyl)ether, m-bis(m-phenoxyphenoxy)benzene, and thioethers in which one or more of the oxygen atoms in these ethers are substituted with sulfur (commonly known as C-ethers).

[0055] Examples of alkyl phenyl ethers include compounds in which polyphenyl ethers are substituted with linear or branched alkyl groups having 6 to 18 carbon atoms, and alkyl diphenyl ethers substituted with one or more alkyl groups are particularly preferred.

[0056] Examples of silicone oils include dimethyl silicone, methyl phenyl silicone, and modified silicones such as long-chain alkyl silicone and fluorosilicone.

[0057] The content of the ester compound represented by general formula (1) in the power transmission lubricant base oil of the present invention is usually 70 mass% or more, preferably 90 mass% or more, more preferably 95 mass% or more, and particularly preferably 98 mass% or more.

[0058] The content of the combined base oil in the power transmission lubricant base oil of the present invention is usually 30 mass % or less, preferably 10 mass % or less, more preferably 5 mass % or less, and particularly preferably 2 mass % or less.

[0059] The present invention also provides a power transmission lubricant containing the power transmission lubricant base oil. In order to improve the performance of the power transmission lubricant, at least one of additives such as antioxidants, metal detergents, ashless dispersants, oiliness agents, antiwear agents, extreme pressure agents, metal deactivators, rust inhibitors, viscosity index improvers, pour point depressants, antifoaming agents, hydrolysis inhibitors, thickeners, corrosion inhibitors, and color stabilizers can be appropriately blended into the base oil. The blending amounts of these are not particularly limited as long as the effects of the present invention are achieved, and specific examples are shown below.

[0060] Examples of the antioxidant include phenol-based antioxidants and amine-based antioxidants. Specific examples of the antioxidant include 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-isopropylidenebispheno 2,4-dimethyl-6-tert-butylphenol, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,2'-dihydroxy-3,3'-di(α-methylcyclohexyl)-5,5'-dimethyl-diphenylmethane, 2,2'-isobutylidenebis(4,6 -dimethylphenol), 2,6-bis(2'-hydroxy-3'-tert-butyl-5'-methylbenzyl)-4-methylphenol, 1,1'-bis(4-hydroxyphenyl)cyclohexane, 2,5-di-tert-amylhydroquinone, 2,5-di-tert-butylhydroquinone, 1,4-dihydroxyanthraquinone, 3-tert-butyl-4-hydroxyanisole, 2-tert-butyl-4-hydroxyanisole, 2,4-dibenzoylresorcinol, 4-tert-butylcatechol, 2,6-di-tert-butyl- 4-Ethylphenol, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,4,5-trihydroxybenzophenone, α-tocopherol, bis[2-(2-hydroxy-5-methyl-3-tert-butylbenzyl)-4-methyl-6-tert-butylphenyl]terephthalate, triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], diphenylamine, monobutyl (including linear and branched chain) diphenylamine, monopentyl (including linear and branched chain) diphenylamine, monohexyl (including linear and branched chain) diphenylamine, monoheptyl (including linear and branched chain) diphenylamine, monooctyl (including linear and branched chain) diphenylamine and other monoalkyl diphenylamines, in particular mono(C4-C9 alkyl) diphenylamines (i.e. Among these, diphenylamines in which one of the two benzene rings of diphenylamine is mono-substituted with an alkyl group, particularly a C4-C9 alkyl group, dibutyl (including straight-chain and branched-chain) diphenylamine, dipentyl (including straight-chain and branched-chain) diphenylamine, dihexyl (including straight-chain and branched-chain) diphenylamine, diheptyl (including straight-chain and branched-chain) diphenylamine, dioctyl (including straight-chain and branched-chain) diphenylamine, dinonyl (including straight-chain and branched-chain) diphenylamine, etc. Examples of the diphenylamine include di(C4-C9 alkylphenyl)amines, particularly di(C4-C9 alkylphenyl)amines (i.e., diphenylamines in which each of the two benzene rings of the diphenylamine is mono-substituted with an alkyl group, particularly a C4-C9 alkyl group, and the two alkyl groups are the same), di(mono C4-C9 alkylphenyl)amines in which the alkyl group on one benzene ring is different from the alkyl group on the other benzene ring, di(di-C4-C9 alkylphenyl)amines in which at least one of the four alkyl groups on the two benzene rings is different from the remaining alkyl groups, naphthylamines such as N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, 4-octylphenyl-1-naphthylamine, and 4-octylphenyl-2-naphthylamine, and phenylenediamines such as p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, and the like.

[0061] Among these, in particular, dioctyl (including straight-chain and branched-chain) diphenylamine, dinonyl (including straight-chain and branched-chain) diphenylamine, N-phenyl-1-naphthylamine, thiodipropionate esters such as di(n-dodecyl) thiodipropionate and di(n-octadecyl) thiodipropionate, and sulfur-based compounds such as phenothiazine are exemplified. These antioxidants can be used alone or in combination of two or more kinds. When using an antioxidant, it is usually desirable to add about 0.01 to 5 mass %, preferably about 0.05 to 3 mass %, based on the base oil.

[0062] Here, in the present specification and claims, the range of the amount of additives may be specified using the expression "with respect to the base oil", such as "0.01 to 5 mass% with respect to the base oil". In this case, the "base oil" used means either a base oil consisting of only the ester compound represented by the general formula (1) or a base oil consisting of a mixture of the ester compound represented by the general formula (1) and a combined base oil. In addition, in the example of "0.01 to 5 mass% with respect to the base oil", it is synonymous with 0.01 to 5 mass parts with respect to 100 mass parts of the base oil.

[0063] Metal detergents include Ca-petroleum sulfonates, overbased Ca-petroleum sulfonates, Ca-alkylbenzene sulfonates, overbased Ca-alkylbenzene sulfonates, Ba-alkylbenzene sulfonates, overbased Ba-alkylbenzene sulfonates, Mg-alkylbenzene sulfonates, overbased Mg-alkylbenzene sulfonates, Na-alkylbenzene sulfonates, overbased Na-alkylbenzene sulfonates, Ca-alkylnaphthalenes Metal sulfonates such as overbased Ca-alkylnaphthalene sulfonates, metal phenates such as Ca-phenates, overbased Ca-phenates, Ba-phenates, and overbased Ba-phenates, metal salicylates such as Ca-salicylate and overbased Ca-salicylate, metal phosphonates such as Ca-phosphonates, overbased Ca-phosphonates, Ba-phosphonates, and overbased Ba-phosphonates, and overbased Ca-carboxylates can be used. When using a metal detergent, it is usually desirable to add about 1 to 10 mass %, preferably about 2 to 7 mass %, to the base oil.

[0064] Examples of ashless dispersants include polyalkenyl succinimide, polyalkenyl succinamide, polyalkenyl benzylamine, polyalkenyl succinate ester, etc. These ashless dispersants may be used alone or in combination, and when used, it is generally desirable to add about 1 to 10 mass %, preferably about 2 to 7 mass %, based on the base oil.

[0065] Examples of oiliness agents include aliphatic saturated and unsaturated monocarboxylic acids such as stearic acid and oleic acid, polymerized fatty acids such as dimer acid and hydrogenated dimer acid, hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid, aliphatic saturated and unsaturated monoalcohols such as lauryl alcohol and oleyl alcohol, aliphatic saturated and unsaturated monoamines such as stearylamine and oleylamine, aliphatic saturated and unsaturated monocarboxylic acid amides such as lauric acid amide and oleic acid amide, glycerin ethers such as batyl alcohol, chimyl alcohol, and selachyl alcohol, alkyl or alkenyl polyglyceryl ethers such as lauryl polyglycerin ether and oleyl polyglyceryl ether, poly(alkylene oxide) adducts of alkyl or alkenyl amines such as di(2-ethylhexyl)monoethanolamine and diisotridecylmonoethanolamine, etc. These oiliness agents may be used alone or in combination, and when used, it is usually desirable to add about 0.01 to 5 mass % to the base oil, preferably about 0.1 to 3 mass %.

[0066] Examples of antiwear agents or extreme pressure agents include phosphorus-based agents such as tricresyl phosphate, cresyl diphenyl phosphate, alkylphenyl phosphates, phosphoric acid esters such as tributyl phosphate and dibutyl phosphate, phosphorous acid esters such as tributyl phosphite, dibutyl phosphite and triisopropyl phosphite, and their amine salts, sulfur-based agents such as sulfurized oils and fats, sulfurized fatty acids such as sulfurized oleic acid, dibenzyl disulfide, sulfurized olefins and dialkyl disulfides, and organometallic compounds such as Zn-dialkyl dithiophosphate, Zn-dialkyl dithiophosphate, Mo-dialkyl dithiophosphate and Mo-dialkyl dithiocarbamate. These antiwear agents may be used alone or in combination, and when used, it is usually desirable to add about 0.01 to 10 mass%, preferably about 0.1 to 5 mass%, to the base oil.

[0067] Examples of metal deactivators include benzotriazole-based, thiadiazole-based, and gallic acid ester-based compounds, etc. These metal deactivators may be used alone or in combination, and when used, they are usually added in an amount of about 0.01 to 0.4% by mass, preferably about 0.01 to 0.2% by mass, based on the base oil.

[0068] Examples of the rust inhibitor include alkyl or alkenyl succinic acid derivatives such as dodecenyl succinic acid half ester, octadecenyl succinic acid anhydride, and dodecenyl succinic acid amide, polyhydric alcohol partial esters such as sorbitan monooleate, glycerin monooleate, and pentaerythritol monooleate, metal sulfonates such as Ca-petroleum sulfonate, Ca-alkylbenzene sulfonate, Ba-alkylbenzene sulfonate, Mg-alkylbenzene sulfonate, Na-alkylbenzene sulfonate, Zn-alkylbenzene sulfonate, and Ca-alkylnaphthalene sulfonate, amines such as rosin amine and N-oleyl sarcosine, and dialkyl phosphite amine salts. These rust inhibitors may be used alone or in combination, and when used, they are usually added in an amount of 0.01 to 5 mass%, preferably about 0.05 to 2 mass%, based on the base oil.

[0069] Examples of viscosity index improvers include olefin copolymers such as polyalkyl methacrylate, polyalkylstyrene, polybutene, ethylene-propylene copolymer, styrene-diene copolymer, styrene-maleic anhydride copolymer, etc. These viscosity index improvers may be used alone or in combination, and when used, they are usually added in an amount of about 0.1 to 15 mass %, preferably about 0.5 to 7 mass %, based on the base oil.

[0070] Examples of pour point depressants include condensates of chlorinated paraffin and alkylnaphthalene, condensates of chlorinated paraffin and phenol, and the above-mentioned viscosity index improvers such as polyalkyl methacrylate, polyalkylstyrene, polybutene, etc. These pour point depressants may be used alone or in combination, and when used, they are usually added in an amount of about 0.01 to 5 mass %, preferably about 0.1 to 3 mass %, based on the base oil.

[0071] As the defoaming agent, liquid silicone is suitable, and when this is used, the amount added is usually about 0.0005 to 0.01% by mass relative to the base oil.

[0072] As the hydrolysis inhibitor, epoxy compounds such as alkyl glycidyl ethers, alkyl glycidyl esters, alkylene glycol glycidyl ethers, alicyclic epoxies, and phenyl glycidyl ether, and carbodiimide compounds such as di-tert-butylcarbodiimide and 1,3-di-p-tolylcarbodiimide can be used, and the amount is usually about 0.05 to 2 mass % relative to the base oil.

[0073] The power transmission lubricating base oil of the present invention can be made into a "grease" by appropriately combining a thickener.

[0074] Examples of thickeners include metal soap-based thickeners, complex metal soap-based thickeners, and non-soap-based thickeners.

[0075] Examples of metal soap-based thickeners include sodium soaps, calcium soaps, lithium soaps, and in particular, lithium salts of aliphatic carboxylates having a hydroxyl group such as lithium-12-hydroxystearate, lithium salts of aliphatic carboxylates such as lithium stearate, and mixtures thereof.

[0076] Examples of the complex metal soap thickener include a complex of a monovalent metal salt of an aliphatic carboxylate having a hydroxyl group and a divalent metal salt of an aliphatic carboxylate. Specific examples include lithium complex soap and aluminum complex soap.

[0077] Examples of non-soap thickeners include bentonite, silica aerogel, sodium terephthalamate, polytetrafluoroethylene, boron nitride, and urea compounds (including alicyclic, aromatic, aliphatic, diurea, triurea, tetraurea, and urea-urethane compounds).

[0078] Among the above, from the viewpoints of heat resistance, water resistance, and shear stability, lithium soaps, lithium complex soaps, and urea compounds are suitable as thickeners, and urea compounds are particularly preferred.

[0079] These thickeners can be used alone or in combination of two or more kinds, and the amount added is not particularly limited as long as the desired effect is achieved.

[0080] Examples of corrosion inhibitors include sodium sulfonate and sorbitan ester, and they are usually added in an amount of about 0.1 to 3.0% by mass to the base oil.

[0081] Examples of color stabilizers include substituted hydroquinone and furfural azine, and they are usually added in an amount of about 0.01 to 0.1% by mass to the base oil.

[0082] The thus obtained lubricating oil for power transmission of the present invention contains a base oil having a high traction coefficient and flash point and excellent low-temperature fluidity, as described above, and is therefore suitable as a lubricating oil for traction drives.

[0083] The power transmission lubricant base oil and the ester compound represented by the general formula (1) of the present invention can be added to a power transmission lubricant (particularly a traction drive lubricant) to improve the traction coefficient of the power transmission lubricant, and therefore can be used as a traction coefficient improver.

[0084] The lubricating oil for power transmission of the present invention has high power transmission performance, low vibration and noise generation, and a high flash point, and can therefore be used as a lubricating oil for traction drives, i.e., power transmission devices consisting of two or more rotating bodies. Devices that employ such traction drives include, for example, motors, transmissions, generators, reducers, etc., of automobiles, ships, aircraft, precision instruments, robots, etc. EXAMPLES

[0085] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The physical and chemical properties of the lubricating base oil and the lubricating oil composition in each example were evaluated by the following methods. Reagents were used for compounds not specifically mentioned.

[0086] <Compound used> Cyclohexanecarboxylic acid: Sigma-Aldrich 2-Methyl-cyclohexanecarboxylic acid: Sigma-Aldrich 3-Methyl-cyclohexanecarboxylic acid: Sigma-Aldrich 4-Methyl-cyclohexanecarboxylic acid: Sigma-Aldrich Benzoic acid: Tokyo Chemical Industry Co., Ltd., product name "Benzoic Acid" 1-Nonanoic acid: manufactured by Tokyo Chemical Industry Co., Ltd., product name "Nonanoic Acid" 2-Hexyl-1-decanol: manufactured by Tokyo Chemical Industry Co., Ltd., product name "2-Hexyl-1-decanol" 3,5-Dimethyl-cyclohexanecarboxylic acid: Referring to JP-A-49-135950, 3,5-dimethylbenzoic acid (Tokyo Chemical Industry Co., Ltd.) was subjected to a hydrogenation reaction in the presence of a 5% by mass palladium-carbon catalyst, and the resulting crude product was purified by distillation to obtain 3,5-dimethylcyclohexanecarboxylic acid. 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octanol: Nissan Chemical Co., Ltd., product name "Fine Oxocol 180" Diisodecyl adipate: Product name "Sanso Cizer DIDA" manufactured by New Japan Chemical Co., Ltd. Mineral oil Y: NOF Corporation, product name "Polybutene 0N"

[0087] (a) Acid value (AV) Measurements were performed in accordance with JIS K2501 (2003) with a detection limit of 0.01 mg KOH / g.

[0088] (b) Hydroxyl value (OHV) The measurement was performed in accordance with JIS K0070 (1992) with a detection limit of 0.1 mg KOH / g.

[0089] [Measurement of physical properties of lubricant base oil] (c) Traction coefficient The maximum traction coefficient was measured when testing was performed using the following equipment and conditions, and this was taken as the traction coefficient (60°C, 140°C). [Measurement conditions] Equipment: Ball-on-ring type friction tester (Phoenix Tribology, TE54 model) Test piece shape: Upper test piece (25 mm diameter ball), lower test piece (50 mm diameter ring) Test piece material: SUJ2 Slip rate: 5% Sample temperature: 60℃, 140℃ Load: 150N <Traction coefficient (60℃) evaluation> A: 0.090 or more B: 0.080 or more and less than 0.090 C: Less than 0.080 <Traction coefficient (140℃) evaluation> A: 0.085 or more B: 0.075 or more and less than 0.085 C: Less than 0.075

[0090] (d) Low temperature fluidity test (pour point) The pour point was measured in accordance with JIS-K-2269 (1987). <Low temperature fluidity evaluation> A: -35℃ or less B: Over -35℃ and below -30℃ C: Above -30℃

[0091] (e) Flash point Measurements were performed in accordance with JIS K2265 (Cleveland open type). <Flash point evaluation> A: 200℃ or higher B: 185℃ or higher but less than 200℃ C: Less than 185℃

[0092] (f) Evaluation of power transmission lubricant base oils In the evaluation of lubricant base oils for power transmission, the traction coefficient, low temperature fluidity and flash point are evaluated as follows: if the result is C 1 or more, it is rated as unsuitable; if the result is B 2 or less (other evaluations are A), it is rated as good; and if the result is B 1 or less (other evaluations are A), it is rated as particularly good.

[0093] (g) IR spectrum The IR spectrum of the obtained ester compound was measured by the ATR method (attenuated total reflection method) using an infrared spectrometer (Spectrum 400, manufactured by PerkinElmer Japan Co., Ltd.).

[0094] (h) Proton nuclear magnetic resonance spectrum ( 1 H-NMR) The ester compound thus obtained was subjected to a nuclear magnetic resonance spectrometer (Bruker, DRX-500). 1 H-NMR (500 MHz, deuterated chloroform) was measured.

[0095] [Example 1] In a 1-liter four-neck flask equipped with a stirrer, a thermometer, and a water fractionation receiver with a condenser, 312.8 g (2.20 mol) of 2-methyl-cyclohexane carboxylic acid, 541.0 g (2.00 mol) of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octanol, 0.8 g of tin oxide, and 30 g of xylene as an entrainer were charged, and the flask was replaced with nitrogen, and then the temperature was gradually raised to 230 ° C. While adjusting the degree of vacuum so that xylene refluxed, the generated water was removed in the water fractionation receiver with the theoretical amount of generated water (36.0 g) as a target, and an esterification reaction was performed. After the reaction was completed, the remaining 2-methyl-cyclohexane carboxylic acid and xylene were removed by distillation under reduced pressure to obtain an esterified crude product. Next, the obtained esterified crude product was neutralized with 1.5 times the equivalent of an aqueous solution of caustic soda relative to the acid value, and then repeatedly washed with water until it became neutral. Magnesium sulfate was added to the obtained esterified crude product for dehydration, and the magnesium sulfate was then removed by filtration to obtain 631.5 g (1.60 mol) of 2-methyl-cyclohexanecarboxylate 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl. The acid value of the obtained ester compound was 0.01 mgKOH / g or less, and the hydroxyl value was 1 mgKOH / g or less. The physical properties of the ester compound evaluated as a power transmission lubricant base oil (A) are shown in Table 1. The IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 2-methyl-cyclohexanecarboxylate, 1 The H-NMR spectrum was measured and is shown in Figures 1 and 2. 1 The peak at around 7.27 ppm in the H-NMR spectrum is the peak of residual protons in the solvent, deuterated chloroform.

[0096] IR(cm -1 ):2951,2866,1732,1466,1393,1378,1364,1317,1250,1172,1132,1045,1009

[0097] [Example 2] 671.0g (1.70mol) of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3-methyl-cyclohexane carboxylate was obtained in the same manner as in Example 1, except that 2-methyl-cyclohexane carboxylic acid was replaced with 312.8g (2.20mol) of 3-methyl-cyclohexane carboxylate. The acid value of the obtained ester compound was 0.01 mgKOH / g or less, and the hydroxyl value was 1 mgKOH / g or less. The physical properties of the ester compound evaluated as a power transmission lubricant base oil (B) are shown in Table 1. The IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3-methyl-cyclohexanecarboxylate, 1 The H-NMR spectrum was measured and is shown in Figures 3 and 4. 1 The peak at around 7.27 ppm in the H-NMR spectrum is the peak of residual protons in the solvent, deuterated chloroform.

[0098] IR(cm -1 ):2950,2866,1732,1458,1392,1377,1364,1247,1215,1176,1137,1089,1045,1006,969

[0099] [Example 3] 678.8g (1.72mol) of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 4-methyl-cyclohexane carboxylate was obtained in the same manner as in Example 1, except that 312.8g (2.20mol) of 4-methyl-cyclohexane carboxylate was used instead of 2-methyl-cyclohexane carboxylate. The acid value of the obtained ester compound was 0.01 mgKOH / g or less, and the hydroxyl value was 1 mgKOH / g or less. The physical properties of the ester compound evaluated as a power transmission lubricant base oil (C) are shown in Table 1. The IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 4-methyl-cyclohexanecarboxylate, 1 The H-NMR spectrum was measured and is shown in Figures 5 and 6. 1The peak at around 7.27 ppm in the H-NMR spectrum is the peak of residual protons in the solvent, deuterated chloroform.

[0100] IR(cm -1 ):2950,2867,1731,1467,1456,1392,1377,1364,1246,1182,1138,1036,991

[0101] [Example 4] 637.6g (1.56mol) of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3,5-dimethyl-cyclohexane carboxylate was obtained in the same manner as in Example 1, except that 2-methyl-cyclohexane carboxylate was replaced with 343.7g (2.20mol) of 3,5-dimethyl-cyclohexane carboxylate. The acid value of the obtained ester compound was 0.01 mgKOH / g or less, and the hydroxyl value was 1 mgKOH / g or less. The physical properties of the ester compound evaluated as a power transmission lubricant base oil (D) are shown in Table 1. The IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 3,5-dimethyl-cyclohexanecarboxylate, 1 The H-NMR spectrum was measured and is shown in Figures 7 and 8. 1 The peak at around 7.27 ppm in the H-NMR spectrum is the peak of residual protons in the solvent, deuterated chloroform.

[0102] IR(cm -1 ):2950,2869,1732,1458,1392,1377,1364,1280,1245,1177,1140,1104,1011,970,946

[0103] [Example 5] In the same manner as in Example 1, except that 2-methyl-cyclohexanecarboxylic acid was changed to 282.0 g (2.20 mol) of cyclohexanecarboxylic acid, 624.3 g (1.64 mol) of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl cyclohexanecarboxylate was obtained. The acid value of the obtained ester compound was 0.01 mgKOH / g or less, and the hydroxyl value was 1 mgKOH / g or less. The physical properties of the ester compound evaluated as a power transmission lubricant base oil (E) are shown in Table 1. The IR spectrum of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl cyclohexanecarboxylate, 1 The H-NMR spectrum was measured and is shown in Figures 9 to 10. 1 The peak at around 7.27 ppm in the H-NMR spectrum is the peak of residual protons in the solvent, deuterated chloroform.

[0104] IR(cm -1 ):2935,2860,1732,1466,1451,1392,1377,1364,1311,1274,1245,1226,1193,1167,1132, 1076, 1038, 968, 926, 894, 845, 754

[0105] [Comparative Example 1] Table 2 shows the physical properties of diisodecyl adipate when it was evaluated as a power transmission lubricant base oil (a).

[0106] [Comparative Example 2] Table 2 shows the physical properties of mineral oil Y when it was evaluated as a power transmission lubricant base oil (b).

[0107] [Comparative Example 3] 646.7g (1.76mol) of 2-hexyl-1-decyl 3-methyl-cyclohexane carboxylate was obtained in the same manner as in Example 1, except that 2-methyl-cyclohexane carboxylate was replaced with 328.5g (2.31mol) of 3-methyl-cyclohexane carboxylate and 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octanol was replaced with 509.1g (2.10mol) of 2-hexyl-1-decanol. The acid value of the obtained compound was 0.01 mgKOH / g or less, and the hydroxyl value was 1 mgKOH / g or less. The physical properties of the compound when evaluated as a power transmission lubricant base oil (c) are shown in Table 2.

[0108] [Comparative Example 4] 706.4 g (1.72 mol) of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl 1-nonanoate was obtained in the same manner as in Example 1, except that 2-methyl-cyclohexanecarboxylic acid was replaced with 348.1 g (2.20 mol) of 1-nonanoic acid. The acid value of the obtained compound was 0.01 mgKOH / g or less, and the hydroxyl value was 1 mgKOH / g or less. The physical properties of the compound when evaluated as a power transmission lubricant base oil (d) are shown in Table 2.

[0109] [Comparative Example 5] In the same manner as in Example 1, except that 2-methyl-cyclohexanecarboxylic acid was changed to 268.7 g (2.20 mol) of benzoic acid, 651.8 g (1.74 mol) of 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyl-1-octyl benzoate was obtained. The acid value of the obtained compound was 0.01 mgKOH / g or less, and the hydroxyl value was 1 mgKOH / g or less. The physical properties of the compound when evaluated as a power transmission lubricant base oil (e) are shown in Table 2.

[0110] [Table 1]

[0111] [Table 2]

[0112] From Table 1, it can be seen that the power transmission lubricant base oils of the present invention described in Examples 1 to 5 have high traction coefficients (60°C) of 0.090 or more and traction coefficients (140°C) of 0.085 or more, pour points of -30°C or less, and high flash points of 190°C or more. [Industrial Applicability]

[0113] Since the power transmission lubricant base oil of the present invention has a high traction coefficient, a high flash point, and good low-temperature fluidity, it can be suitably used as a power transmission lubricant base oil (particularly, a traction drive lubricant base oil) for automobiles, ships, aircraft, precision instruments, and the like.

Claims

1. General formula (1) 【Chemistry 1】 [In the formula, R １ ~R ５ are the same or different and each represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. The present invention relates to a power transmission lubricating base oil containing an ester compound represented by the formula:

2. R represented by formula (1) １ ~R ５ and are the same or different and each is a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a tert-butyl group.

3. The power transmission lubricating base oil according to claim 1 or 2, wherein the content of the ester compound represented by the general formula (1) in the power transmission lubricating base oil is 70 mass% or more.

4. The power transmission lubricant base oil according to any one of claims 1 to 3, wherein the power transmission lubricant base oil is a traction drive lubricant base oil.

5. A lubricating oil for power transmission comprising the lubricating oil base oil for power transmission according to any one of claims 1 to 4.

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