Lubricant base oil

Abstract

Provided are: lubricant base oil having a natural origin index (ISO 16128) of 90-100% and containing a diester compound (A) and a hydrocarbon compound (B); and a lubricant composition containing the lubricant base oil.

Description

Lubricant base oil

[0001] The present invention relates to a lubricating base oil and a lubricating oil composition comprising the lubricating base oil.

[0002] In recent years, lubricating oil compositions for use in automobiles have been developed with consideration given to their impact on the environment. For example, Patent Document 1 discloses a lubricating oil composition in which the structure and content of polymer components, the NOACK evaporation amount, and the content of fractions having a boiling point in the range of 350 to 400°C are adjusted with the aim of reducing fuel consumption in order to reduce carbon dioxide emissions.

[0003] Japanese Patent Application Laid-Open No. 2021-25025

[0004] From the viewpoint of life cycle assessment, it is becoming increasingly necessary to consider the environmental impact of lubricating oil compositions not only during use but also upon disposal. Therefore, there is a demand for lubricating oil base oils that can be used to prepare lubricating oil compositions that are excellent in various properties, such as rubber compatibility, while reducing the environmental impact upon disposal.

[0005] The present invention provides a lubricating base oil having a natural origin index (ISO 16128) of 90 to 100% and containing a diester compound and a hydrocarbon compound, as well as a lubricating oil composition containing the lubricating base oil. Specifically, the present invention provides the lubricating base oil and the lubricating oil composition according to the following aspects [1] to

[18] . [1] A lubricating base oil having a natural origin index (ISO 16128) of 90 to 100% and containing a diester compound (A) and a hydrocarbon compound (B). [2] The lubricating base oil according to [1] above, wherein the hydrocarbon compound (B) has 18 or more carbon atoms. [3] The lubricating base oil according to [1] above, wherein the hydrocarbon compound (B) has 20 or more carbon atoms. [4] The lubricating base oil according to any one of [1] to [3] above, wherein the diester compound (A) has 12 or more carbon atoms. [5] The lubricating base oil according to any one of [1] to [4] above, wherein the diester compound (A) comprises a diester compound having one or more branched chain structures. [6] The lubricating base oil according to any one of [1] to [5] above, wherein the diester compound (A) comprises a saturated diester compound. [7] The lubricating base oil according to any one of [1] to [6] above, wherein the diester compound (A) comprises a compound (A1) represented by the following general formula (a-1): (In the above formula, R １ and R ２ are each independently a hydrocarbon group. A is an alkylene group having 2 to 5 carbon atoms. R １ , R ２ and A have a total carbon number of 10 or more.) [8] The lubricating base oil according to the above [7], wherein A in the general formula (a-1) is a branched alkylene group. [9] R in the general formula (a-1) １ and R ２ are each independently a linear alkyl group having 5 or more carbon atoms.

[10] The lubricating base oil according to any one of [1] to [6] above, wherein the diester compound (A) is a compound (A11) represented by the following general formula (a-11): (In the above formula, R １ and R ２ are each independently a hydrocarbon group. １ and R ２The total number of carbon atoms in R in the general formula (a-11) is 7 or more. １ and R ２ are each independently a linear alkyl group having 5 or more carbon atoms.

[12] The lubricating base oil according to any one of [1] to

[11] above, wherein the pour point of the lubricating base oil is 0°C or lower.

[13] The lubricating base oil according to any one of [1] to

[12] above, wherein a test nitrile rubber is immersed in the lubricating base oil and the volume change of the test nitrile rubber is 0% or higher but less than 12%, as measured in accordance with JIS K6258 at 150°C for 72 hours.

[14] The lubricating base oil according to any one of [1] to

[13] above, wherein the flash point of the lubricating base oil is 160°C or higher.

[15] The lubricating base oil according to any one of [1] to

[14] above, wherein the content ratio of component (A) to component (B) [(A) / (B)] is 0.05 or higher but 19.0 or lower, in mass ratio.

[16] The lubricating base oil according to any one of [1] to

[15] above, wherein the natural origin index (ISO 16128) of component (A) is 90 to 100 mass% and the natural origin index (ISO 16128) of component (B) is 90 to 100 mass%.

[17] A lubricating oil composition comprising the lubricating base oil according to any one of [1] to

[16] above.

[18] The lubricating oil composition according to

[17] above, further comprising one or more lubricating oil additives selected from the group consisting of pour point depressants, viscosity index improvers, antioxidants, extreme pressure agents, metal detergents, ashless dispersants, metal deactivators, friction modifiers, rust inhibitors, and antifoaming agents.

[0006] The lubricating base oil of a preferred embodiment of the present invention is a lubricating base oil that reduces the environmental impact when disposed of, and yet can be used to prepare a lubricating oil composition that is excellent in various properties such as rubber compatibility.

[0007] For the numerical ranges described herein, the upper and lower limits can be arbitrarily combined. For example, when a numerical range is described as "preferably 30 to 100, more preferably 40 to 80," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described herein. Furthermore, for example, when a numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described herein. In addition, for example, when a numerical range described herein as "60 to 100" means a range of "60 or more (60 or more) and 100 or less (100 or less)."

[0008] In this specification, the kinematic viscosity and viscosity index refer to values ​​measured or calculated in accordance with JIS K2283:2000.

[0009] [Composition of Lubricating Base Oil] The lubricating base oil of one embodiment of the present invention has a natural origin index (ISO 16128) of 90 to 100% and contains a diester compound (A) and a hydrocarbon compound (B). In this specification, the natural origin index is a value calculated in accordance with ISO 16128 and indicates the proportion of natural raw materials derived from plants, animals, algae, microorganisms such as bacteria and fungi, and minerals in the raw materials used to produce the lubricating base oil. In other words, since the lubricating base oil of one embodiment of the present invention has a natural origin index calculated in accordance with ISO 16128 of 90 to 100%, 90% or more of the raw materials are derived from natural raw materials.

[0010] For example, in the automotive industry, from the perspective of life cycle assessment, there is a demand for lubricating oil compositions to have a reduced environmental impact upon disposal. In one embodiment of the present invention, the lubricating base oil is composed of raw materials having a natural origin index (ISO 16128) of 90 to 100% in order to reduce the environmental impact upon disposal. Furthermore, when the lubricating base oil of one embodiment of the present invention is composed of plant-derived raw materials, even if carbon dioxide is generated by combustion upon disposal, the plants that make up the raw materials absorb carbon dioxide during their growth, so that the amount of carbon dioxide in the atmosphere does not increase throughout the entire life cycle, thereby suppressing the balance of carbon dioxide emissions. Furthermore, a lubricating base oil with a natural origin index of 100% is considered "carbon neutral," meaning that carbon dioxide emissions are essentially zero.

[0011] The natural origin index of the lubricating base oil of one embodiment of the present invention, calculated in accordance with ISO 16128, may be 91 to 100%, 92 to 100%, 93 to 100%, 94 to 100%, 95 to 100%, 96 to 100%, 97 to 100%, 98 to 100%, 99 to 100%, or 100%.

[0012] The lubricating base oil of one embodiment of the present invention comprises a diester compound (A) and a hydrocarbon compound (B). The lubricating base oil comprising components (A) and (B) has excellent viscosity characteristics, low-temperature fluidity, insulating properties, safety due to a high flash point, and rubber compatibility, and can be used to prepare a lubricating oil composition having these excellent properties.

[0013] The lubricating base oil of one embodiment of the present invention may further contain other base oils besides components (A) and (B) as long as the natural origin index is in the range of 90 to 100% without impairing the effects of the present invention. In the lubricating base oil of one embodiment of the present invention, the total content of components (A) and (B) may be 60 to 100% by mass, 70 to 100% by mass, 80 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, 97 to 100% by mass, 98 to 100% by mass, 99 to 100% by mass, or 100% by mass, based on the total amount (100% by mass) of the lubricating base oil. Hereinafter, components (A) and (B) contained in the lubricating base oil of one embodiment of the present invention will be described.

[0014] <Component (A): Diester Compound> The diester compound (A) (hereinafter also referred to as "component (A)") contained in the lubricating base oil of one embodiment of the present invention can be produced, for example, by an esterification reaction between a dicarboxylic acid component and an alcohol component, or by an esterification reaction between a monocarboxylic acid component and a diol component. For example, 2-ethylhexyl palmitate, which is described in Patent Document 1 and is generally known as a lubricating base oil, is produced by an esterification reaction between palmitic acid and 2-ethylhexanol. However, 2-ethylhexanol is a petroleum-derived raw material and does not fall under the category of natural raw materials specified in ISO 16128. Therefore, the natural origin index of 2-ethylhexyl palmitate is not 100%. On the other hand, since the natural origin index (ISO 16128) of the lubricating base oil of one embodiment of the present invention is 90 to 100%, it is preferable that the dicarboxylic acid component or monocarboxylic acid component, and the alcohol component or diol component, which are raw materials for component (A) used in one embodiment of the present invention, are derived from natural raw materials. By including a diester compound obtained from these natural raw materials as component (A), a lubricating base oil with reduced environmental impact upon disposal can be obtained. Furthermore, from the viewpoint of obtaining a carbon-neutral lubricating base oil, component (A) used in one embodiment of the present invention is preferably composed solely of diester compounds produced from natural raw materials (dicarboxylic acid or monocarboxylic acid components, and alcohol or diol components). The natural raw materials for the dicarboxylic acid or monocarboxylic acid components and alcohol or diol components used as raw materials for component (A) are preferably plant raw materials, more preferably plant raw materials selected from oil palm, corn, castor bean, soybean, and rice, and even more preferably plant raw materials selected from oil palm, corn, and castor bean.

[0015] The natural origin index of the component (A) used in one embodiment of the present invention, calculated in accordance with ISO 16128, may be 90 to 100%, 91 to 100%, 92 to 100%, 93 to 100%, 94 to 100%, 95 to 100%, 96 to 100%, 97 to 100%, 98 to 100%, 99 to 100%, or 100%.

[0016] In one embodiment of the lubricating base oil of the present invention, by containing component (A), various properties (e.g., viscosity characteristics, low-temperature fluidity, insulating properties, flash point, rubber compatibility, etc.) are good, and in particular, the viscosity characteristics and low-temperature fluidity are good, and the flash point is high, making it possible to obtain a lubricating base oil with excellent handleability. However, component (A) has the problem of poor rubber compatibility. To address this problem, the lubricating base oil of one embodiment of the present invention contains a hydrocarbon compound (B) together with component (A), thereby providing a lubricating base oil with improved rubber compatibility.

[0017] Furthermore, component (A) used in one embodiment of the present invention preferably contains a diester compound having one or more branched chain structures, and more preferably contains a diester compound having one or more branched chain structures and 12 or more carbon atoms. By containing a diester compound having one or more branched chain structures, a lubricating base oil with excellent properties (e.g., viscosity characteristics, low-temperature fluidity, insulating properties, flash point, rubber compatibility, etc.) can be obtained. For example, a diester compound having one or more branched chain structures has greater steric hindrance than a diester compound having only a linear chain structure, making it difficult for molecules to stack together, resulting in a lubricating base oil with improved viscosity characteristics, low-temperature fluidity, and flowability. Therefore, the use of such a lubricating base oil can produce a lubricating oil composition with excellent various lubricating properties. Furthermore, from the same viewpoint as above, component (A) used in one embodiment of the present invention preferably contains a saturated diester compound, more preferably contains a saturated diester compound having one or more branched chain structures, and even more preferably contains a saturated diester compound having one or more branched chain structures and 12 or more carbon atoms. The number of branched chain structures in component (A) used in one embodiment of the present invention is 1 or more, but from the viewpoint of ensuring a certain level of intermolecular force and providing a lubricating base oil with a high flash point, the number is preferably 1 to 5, more preferably 1 to 4, even more preferably 1 to 3, and still more preferably 1 to 2.

[0018] In the lubricating base oil of one embodiment of the present invention, the content of the saturated diester compound in component (A) is preferably 50 to 100 mass%, 60 to 100 mass%, 70 to 100 mass%, 80 to 100 mass%, 90 to 100 mass%, 95 to 100 mass%, 98 to 100 mass%, 99 to 100 mass%, or 100 mass%, relative to 100 mass% of the total amount of component (A) contained in the lubricating base oil.

[0019] In the lubricating base oil of one embodiment of the present invention, the content of the unsaturated diester compound in component (A) is preferably less than 50 mass%, less than 40 mass%, less than 30 mass%, less than 20 mass%, less than 10 mass%, less than 5.0 mass%, less than 3.0 mass%, less than 2.0 mass%, less than 1.0 mass%, less than 0.1 mass%, less than 0.01 mass%, less than 0.001 mass%, or less than 0.0001 mass%, based on the total amount (100 mass%) of the lubricating base oil.

[0020] In the lubricating base oil of one embodiment of the present invention, the number of carbon atoms in the diester compound is preferably 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more, from the viewpoint of obtaining a lubricating base oil that is excellent in viscosity characteristics, low-temperature fluidity, and insulating properties, has a high flash point, and is easy to handle. It may also be 20 or more, 21 or more, 22 or more, or 23 or more. Furthermore, from the viewpoint of obtaining a lubricating base oil with improved low-temperature fluidity, the number of carbon atoms in the diester compound is preferably 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 48 ​​or less, 46 or less, 45 or less, 44 or less, 42 or less, 40 or less, 38 or less, 36 or less, 34 or less, 32 or less, 30 or less, 29 or less, 28 or less, 27 or less, 26 or less, 25 or less, 24 or less, 23 or less, 22 or less, or 21 or less.

[0021] Component (A) used in one embodiment of the present invention preferably contains a compound (A1) represented by the following general formula (a-1) from the viewpoint of providing a lubricating base oil excellent in various properties (e.g., viscosity characteristics, low-temperature fluidity, insulating properties, flash point, etc.), and more preferably contains a compound (A11) represented by the following general formula (a-11) from the viewpoint of providing a lubricating base oil with further improved low-temperature fluidity.

[0022] In the general formulae (a-1) and (a-11), R １ and R ２ are each independently a hydrocarbon group. The hydrocarbon group may have one or more structures selected from a linear structure, a branched structure, a ring structure, and an aromatic ring structure. In the general formula (a-1), A is an alkylene group having 2 to 5 carbon atoms, and R １ , R ２ and A have a total of 10 or more carbon atoms. １ and R ２ The total number of carbon atoms is 7 or more.

[0023] Examples of the alkylene group that can be selected as A in general formula (a-1) include ethylene, 1,1-propylene, 1,2-propylene, 1,3-propylene, 1,1-butylene, 1,2-butylene, 1,3-butylene, 1,4-butylene, 2,2-butylene, 2,3-butylene, 1,1-pentylene, 1,2-pentylene, 1,3-pentylene, 1,4-pentylene, 1,5-pentylene, 2,2-pentylene, 2,3-pentylene, 2,4-pentylene, 2,5-pentylene, etc. The alkylene group may be a linear alkylene group or a branched alkylene group, but is preferably a branched alkylene group from the viewpoint of obtaining a lubricating base oil with further improved low-temperature fluidity. The alkylene group has 2 to 5 carbon atoms, preferably 2 to 4 carbon atoms, more preferably 3 or 4 carbon atoms, and even more preferably 3 carbon atoms.

[0024] R in the general formula (a-1) １ , R ２and A. From the viewpoint of obtaining a lubricating base oil having excellent viscosity characteristics, low-temperature fluidity, and insulating properties, a high flash point, and excellent handleability, the total number of carbon atoms in A is preferably 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, or 17 or more, and may further be 18 or more, 19 or more, 20 or more, or 21 or more. Furthermore, from the viewpoint of obtaining a lubricating base oil having better low-temperature fluidity, the total number of carbon atoms in A is preferably 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 48 ​​or less, 46 or less, 45 or less, 44 or less, 42 or less, 40 or less, 38 or less, 36 or less, 34 or less, 32 or less, 30 or less, 29 or less, 28 or less, 27 or less, 26 or less, 25 or less, 24 or less, 23 or less, 22 or less, 21 or less, 20 or less, or 19 or less.

[0025] R in the general formula (a-11) １ and R ２ From the viewpoint of obtaining a lubricating base oil having excellent viscosity characteristics, low-temperature fluidity, and insulating properties, a high flash point, and excellent handleability, the total carbon number is preferably 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, or 14 or more, and may further be 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more. Furthermore, from the viewpoint of obtaining a lubricating base oil having better low-temperature fluidity, the total carbon number is preferably 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 48 ​​or less, 46 or less, 45 or less, 44 or less, 42 or less, 40 or less, 38 or less, 36 or less, 34 or less, 32 or less, 30 or less, 29 or less, 28 or less, 27 or less, 26 or less, 25 or less, 24 or less, 23 or less, 22 or less, 21 or less, 20 or less, 19 or less, 18 or less, 17 or less, or 16 or less.

[0026] R in the general formulae (a-1) and (a-11) １ and R ２From the viewpoint of obtaining a lubricating base oil that is excellent in viscosity characteristics, low-temperature fluidity, and insulating properties, and that has a high flash point and excellent handleability, the number of carbon atoms in each of the above is preferably 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, or 7 or more, and may further be 8 or more or 9 or more. Furthermore, from the viewpoint of obtaining a lubricating base oil with better low-temperature fluidity, the number of carbon atoms in each of the above is preferably 35 or less, 34 or less, 32 or less, 30 or less, 28 or less, 26 or less, 24 or less, 22 or less, 20 or less, 18 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, or 8 or less.

[0027] R in the general formulae (a-1) and (a-11) １ and R ２ Examples of the hydrocarbon group that can be selected as the alkyl group include an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, an alkylaryl group, and an arylalkyl group.

[0028] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group (n-propyl group, isopropyl group), a butyl group (n-butyl group, s-butyl group, t-butyl group, isobutyl group), a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a 1-methylheptyl group, a nonyl group, a 1-methyloctyl group, a 1,1-dimethylheptyl group, a decyl group, a 1-methylheptyl group, an undec ... Examples of such groups include ethyldecyl group, dodecyl group, 1-methylundecyl group, tridecyl group, 1-methyldodecyl group, tetradecyl group, 1-methyltridecyl group, pentadecyl group, 1-methyltetradecyl group, hexadecyl group, 1-methylpentadecyl group, 2-hexyldecyl group, heptadecyl group, 1-methylhexadecyl group, octadecyl group, 1-methylheptadecyl group, nonadecyl group, and 1-methyloctadecyl group. １ and R ２ The alkyl group that can be selected as may be a straight chain alkyl group or a branched chain alkyl group.

[0029] Examples of the alkenyl group include ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, methylheptenyl, nonyl, methyloctenyl, decenyl, methylnonyl, undecenyl, methyldecenyl, dodecenyl, methylundecenyl, tridecenyl, methyldodecenyl, tetradecenyl, methyltridecenyl, pentadecenyl, methyltetradecenyl, hexadecenyl, methylpentadecenyl, heptadecenyl, methylhexadecenyl, octadecenyl, methylheptadecenyl, nonadecenyl, and methyloctadecenyl groups. １ and R ２ The alkenyl group that can be selected as may be a straight-chain alkenyl group or a branched-chain alkenyl group.

[0030] Examples of the cycloalkyl group include a cycloalkyl group that may have an alkyl group such as a cyclohexyl group, a dimethylcyclohexyl group, an ethylcyclohexyl group, a propylcyclohexyl group, a butylcyclohexyl group, or a heptylcyclohexyl group. The cycloalkyl group may have one or more substituents selected from a linear alkyl group, a branched alkyl group, a linear alkenyl group, and a branched alkyl group on the ring structure. Examples of the aryl group include a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group, and a terphenyl group. Examples of the alkylaryl group include a tolyl group, a dimethylphenyl group, a butylphenyl group, a nonylphenyl group, a methylbenzyl group, and a dimethylnaphthyl group. Examples of the arylalkyl group include a phenylmethyl group, a phenylethyl group, and a diphenylmethyl group. The alkyl group in the alkylaryl group and the arylalkyl group may be a linear alkyl group or a branched alkyl group.

[0031] Among these, from the viewpoint of obtaining a lubricating base oil that is excellent in viscosity characteristics, low-temperature fluidity, and insulating properties, has a high flash point, and is easy to handle, R １ and R ２are each independently preferably an alkyl group or an alkenyl group, more preferably an alkyl group. １ and R ２ Preferably, at least one of R is a linear alkyl group. １ and R ２ More preferably, both are linear alkyl groups, and R １ and R ２ and R are each preferably a linear alkyl group having 3 or more carbon atoms. １ and R ２ It is even more preferable that both are linear alkyl groups having 5 or more carbon atoms.

[0032] In the lubricating base oil of one embodiment of the present invention, from the viewpoint of obtaining a lubricating base oil having excellent viscosity characteristics, low-temperature fluidity, and insulating properties, and having a high flash point and excellent handleability, the content of component (A1) is preferably 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, 98% by mass or more, or 99% by mass or more based on the total amount (100% by mass) of component (A) contained in the lubricating base oil.

[0033] In the lubricating base oil of one embodiment of the present invention, from the viewpoint of obtaining a lubricating base oil having excellent viscosity characteristics, low-temperature fluidity, and insulating properties, and having a high flash point and excellent handleability, the content of component (A11) is preferably 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, 98% by mass or more, or 99% by mass or more based on the total amount (100% by mass) of component (A) contained in the lubricating base oil.

[0034] In the lubricating base oil of one embodiment of the present invention, from the viewpoint of providing a lubricating base oil that is excellent in viscosity characteristics, low-temperature fluidity, and insulating properties, and that has a high flash point and excellent handleability, the content of component (A) is preferably 1.0 mass% or more, 3.0 mass% or more, 5.0 mass% or more, 6.0 mass% or more, 7.0 mass% or more, 8.0 mass% or more, 9.0 mass% or more, 10.0 mass% or more, or 11.0 mass% or more, based on the total amount (100 mass%) of the lubricating base oil, and may further be 15.0 mass% or more, 20.0 mass% or more, 25.0 mass% or more, 30.0 mass% or more, 35.0 mass% or more, or 40.0 mass% or more. Furthermore, from the viewpoint of obtaining a lubricating base oil having particularly good rubber compatibility, it is preferable to set the content to 95.0 mass % or less, 90.0 mass % or less, 85.0 mass % or less, 80.0 mass % or less, 85.0 mass % or less, 80.0 mass % or less, 75.0 mass % or less, 70.0 mass % or less, 65.0 mass % or less, 60.0 mass % or less, 55.0 mass % or less, 50.0 mass % or less, 45.0 mass % or less, 40.0 mass % or less, 35.0 mass % or less, 30.0 mass % or less, 25.0 mass % or less, or 20.0 mass % or less, and it may further be set to 18.0 mass % or less, 16.0 mass % or less, or 14.0 mass % or less.

[0035] <Component (B): Hydrocarbon Compound> The lubricating base oil of one embodiment of the present invention contains a hydrocarbon compound (B) (hereinafter also referred to as "component (B)"). By containing component (B) together with component (A), the lubricating base oil of one embodiment of the present invention can be a lubricating base oil that is excellent in viscosity characteristics, low-temperature fluidity, and insulating properties, has a high flash point, and is easy to handle, and further has improved rubber compatibility.

[0036] From the viewpoint of providing a lubricating base oil with reduced environmental impact upon disposal, the natural origin index of component (B) used in one embodiment of the present invention, calculated in accordance with ISO 16128, may be 90 to 100%, 91 to 100%, 92 to 100%, 93 to 100%, 94 to 100%, 95 to 100%, 96 to 100%, 97 to 100%, 98 to 100%, 99 to 100%, or 100%. Component (B) used in one embodiment of the present invention is preferably a compound derived from a plant such as oil palm, more preferably a compound derived from a plant selected from oil palm, corn, castor, soybean, and rice, even more preferably a compound derived from a plant selected from oil palm, corn, and castor, and even more preferably a compound derived from oil palm.

[0037] Component (B) used in one aspect of the present invention is derived from natural materials and is a compound composed of carbon atoms and hydrogen atoms. It may be a chain hydrocarbon compound, a cyclic hydrocarbon compound, or an aromatic hydrocarbon compound, but is preferably a chain hydrocarbon compound. More specific examples of component (B) include a compound (B1) selected from reaction products obtained by reacting one or more unsaturated hydrocarbon compounds and hydrogenated products thereof, and a compound (B2) selected from normal paraffins and isoparaffins. Component (B) used in one aspect of the present invention may be used alone or in combination of two or more. It is preferable that component (B), component (B1), and component (B2) used in one aspect of the present invention are compounds having at least one branched chain structure and / or compounds having no unsaturated structure.

[0038] Examples of the unsaturated hydrocarbon compound that constitutes component (B1) include α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0039] The carbon number of the unsaturated hydrocarbon compound constituting component (B1) is preferably 4 or more, more preferably 6 or more, more preferably 8 or more, even more preferably 10 or more, even more preferably 12 or more, still more preferably 14 or more, particularly preferably 16 or more, from the viewpoint of improving various properties and increasing the flash point to obtain a lubricating base oil with excellent handleability, and may further be 18 or more, 20 or more, 22 or more, 24 or more, 26 or more, 28 or more, 30 or more, or 32 or more, and may also be 50 or less, 45 or less, 40 or less, 38 or less, 36 or less, or 34 or less. The kinematic viscosity of component (B1) at 100°C is 2.0 mm ２ / s or more, 2.2mm ２ / s or more, 2.4mm ２ / s or more, 2.6mm ２ / s or more, 2.8mm ２ / s or more, 3.0mm ２ / s or more, 3.2mm ２ / s or more, 3.6mm ２ / s or more, 3.8mm ２ / s or more, 4.0mm ２ / s or more, or 4.2 mm ２ / s or more, and ２ / s or less, 7.8mm ２ / s or less, 7.6mm ２ / s or less, 7.4mm ２ / s or less, 7.2mm ２ / s or less, 7.0mm ２ / s or less, 6.8mm ２ / s or less, 6.6mm２ / s or less, 6.4mm ２ / s or less, 6.2mm ２ / s or less, 6.0mm ２ / s or less, 5.8mm ２ / s or less, 5.6mm ２ / s or less, 5.4mm ２ / s or less, 5.2mm ２ / s or less, 5.0mm ２ / s or less, or 4.8 mm ２ It is preferable to set it to / s or less.

[0040] From the viewpoint of improving various properties, further improving rubber compatibility, and further increasing the flash point to provide a lubricating base oil with excellent handleability, the number of carbon atoms in component (B2) is preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, still more preferably 16 or more, and particularly preferably 18 or more, and may also be 50 or less, 45 or less, 40 or less, 38 or less, 36 or less, 34 or less, 32 or less, or 30 or less. In one embodiment of the present invention, component (B2) used as component (B) is preferably isoparaffin from the viewpoint of improving various properties and providing a lubricating base oil with excellent low-temperature fluidity.

[0041] In one embodiment of the present invention, the component (B) used in the lubricating base oil (B) preferably contains component (B1) from the viewpoint of obtaining a lubricating base oil having excellent viscosity characteristics, low-temperature fluidity, and insulating properties, a high flash point, and excellent handling properties, while further improving rubber compatibility. In the lubricating base oil (B) of one embodiment of the present invention, the content of component (B1) in component (B) is preferably 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, 98% by mass or more, or 99% by mass or more, based on the total amount (100% by mass) of component (B) contained in the lubricating base oil.

[0042] The carbon number of component (B) used in one embodiment of the present invention is, from the viewpoint of improving various properties, further improving rubber compatibility, and further increasing the flash point to provide a lubricating base oil with excellent handleability, preferably 18 or more, more preferably 20 or more, more preferably 22 or more, even more preferably 24 or more, still more preferably 26 or more, still more preferably 28 or more, and particularly preferably 30 or more, and may also be 50 or less, 45 or less, 40 or less, 38 or less, 36 or less, or 34 or less.

[0043] The component (B) used in one embodiment of the present invention may have a limited content of cyclic hydrocarbon compounds and aromatic hydrocarbon compounds.The respective contents of cyclic hydrocarbon compounds and aromatic hydrocarbon compounds in component (B) may be 50 mass% or less, 40 mass% or less, 30 mass% or less, 20 mass% or less, 10 mass% or less, 5.0 mass% or less, 3.0 mass% or less, 2.0 mass% or less, 1.0 mass% or less, 0.1 mass% or less, 0.01 mass% or less, 0.001 mass% or less, or 0.0001 mass% or less, based on the total amount (100 mass%) of component (B) contained in the lubricating base oil.

[0044] In the lubricating base oil of one embodiment of the present invention, the content of component (B) is, based on the total amount (100 mass%) of the lubricating base oil, from the viewpoint of obtaining a lubricating base oil with further improved rubber compatibility, 5.0 mass% or more, 10.0 mass% or more, 15.0 mass% or more, 20.0 mass% or more, 25.0 mass% or more, 30.0 mass% or more, 35.0 mass% or more, 40.0 mass% or more, 45.0 mass% or more, 50.0 mass% or more, 55.0 mass% or more, 60.0 mass% or more, 65.0 mass% or more, 70.0 mass% or more, 75.0 mass% or more, or 80.0 mass% or more. From the viewpoint of further ensuring the content of component (A) and obtaining a lubricating base oil excellent in viscosity characteristics, low-temperature fluidity, and insulating properties, it is preferable that the content be 99.0 mass % or less, 97.0 mass % or less, 95.0 mass % or less, 94.0 mass % or less, 93.0 mass % or less, 92.0 mass % or less, 91.0 mass % or less, 90.0 mass % or less, or 89.0 mass % or less, and it may further be 85.0 mass % or less, 80.0 mass % or less, 75.0 mass % or less, 70.0 mass % or less, 65.0 mass % or less, or 60.0 mass % or less.

[0045] In the lubricating base oil of one embodiment of the present invention, the content ratio of component (A) to component (B) [(A) / (B)] is, in terms of mass ratio, preferably 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, or 0.11 or more, from the viewpoint of providing a lubricating base oil excellent in viscosity characteristics, low-temperature fluidity, and insulating property, and may further be 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, or 0.40 or more. Furthermore, from the viewpoint of providing a lubricating base oil with further improved rubber compatibility, it may be 19.0 or less, 18.0 or more, or It is preferable that the viscosity index be 16.0 or less, 14.0 or less, 12.0 or less, 10.0 or less, 9.0 or less, 8.0 or less, 7.0 or less, 6.0 or less, 5.0 or less, 4.0 or less, 3.0 or less, 2.0 or less, 1.5 or less, 1.0 or less, 0.90 or less, 0.80 or less, 0.75 or less, 0.70 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, 0.25 or less, or 0.20 or less, and may further be 0.18 or less, 0.16 or less, 0.15 or less, or 0.14 or less.

[0046] <Other hydrocarbon compounds> The lubricating base oil of one embodiment of the present invention may further contain other base oils other than components (A) and (B), but the lower the content, the better.For example, in the lubricating base oil of one embodiment of the present invention, the lower the content of mineral oil, the better, and based on the total amount (100 mass%) of the lubricating base oil, it is preferably less than 10 mass%, less than 5.0 mass%, less than 3.0 mass%, less than 2.0 mass%, less than 1.0 mass%, less than 0.1 mass%, less than 0.01 mass%, or less than 0.001 mass%.

[0047] In addition, the lubricating base oil of one embodiment of the present invention may contain ester compounds other than component (A) (monoester compounds, triester compounds, polyester compounds, etc.), but from the viewpoint of obtaining a lubricating base oil with further improved rubber compatibility, the lower the content, the better. The content of each of the ester compounds other than component (A), i.e., monoester compounds, triester compounds, or polyester compounds, is preferably less than 10 mass%, less than 5.0 mass%, less than 3.0 mass%, less than 2.0 mass%, less than 1.0 mass%, less than 0.1 mass%, less than 0.01 mass%, or less than 0.001 mass%, based on the total amount (100 mass%) of the lubricating base oil.

[0048] [Properties of Lubricating Base Oil] The 40°C kinematic viscosity of the lubricating base oil of one embodiment of the present invention is 4.0 mm ２ / s or more, 4.2mm ２ / s or more, 4.5mm ２ / s or more, 4.7mm ２ / s or more, 5.0mm ２ / s or more, 5.2mm ２ / s or more, 5.5mm ２ / s or more, 5.7mm ２ / s or more, 6.0mm ２ / s or more, 6.2mm ２ / s or more, 6.5mm ２ / s or more, 6.7mm ２ / s or more, 7.0mm ２ / s or more, 7.5mm ２ / s or more, 8.0mm ２ / s or more, 8.5mm ２ / s or more, 9.0mm ２ / s or more, or 9.5 mm ２ / s or more, and ２ / s or less, 90mm ２ / s or less, 80mm ２ / s or less, 70mm ２ / s or less, 60mm ２ / s or less, 50mm ２ / s or less, 40mm ２ / s or less, 35mm ２ / s or less, 30mm ２ / s or less, 25mm ２ / s or less, 20mm２ / s or less, 19mm ２ / s or less, 18mm ２ / s or less, or 17 mm ２ / s or less.

[0049] The kinematic viscosity at 100°C of the lubricating base oil of one embodiment of the present invention is 1.0 mm ２ / s or more, 1.2mm ２ / s or more, 1.5mm ２ / s or more, 1.7mm ２ / s or more, 1.8mm ２ / s or more, 2.0mm ２ / s or more, 2.2mm ２ / s or more, 2.5mm ２ / s or more, 2.7mm ２ / s or more, or 3.0 mm ２ / s or more, and ２ / s or less, 9.0mm ２ / s or less, 8.0mm ２ / s or less, 7.0mm ２ / s or less, 6.0mm ２ / s or less, 5.0mm ２ / s or less, 4.5mm ２ / s or less, 4.2mm ２ / s or less, 4.0mm ２ / s or less, 3.8mm ２ / s or less, or 3.5 mm ２ / s or less.

[0050] The viscosity index of the lubricating base oil of one embodiment of the present invention may be 70 or more, 80 or more, 85 or more, 90 or more, 95 or more, 100 or more, 105 or more, 110 or more, 115 or more, 120 or more, 125 or more, or 130 or more.

[0051] From the viewpoint of providing a lubricating base oil that can be easily prepared into a lubricating oil composition that can be used over a wide temperature range, the pour point of the lubricating base oil of one embodiment of the present invention is preferably 0°C or lower, more preferably -10°C or lower, more preferably -20°C or lower, even more preferably -30°C or lower, even more preferably -35°C or lower, still more preferably -37.5°C or lower, even more preferably -40°C or lower, still more preferably -45°C or lower, and particularly preferably -47.5°C or lower. In this specification, pour point refers to a value measured in accordance with JIS K2269.

[0052] The lubricating base oil of one embodiment of the present invention preferably has a volume resistivity of 1.0 × 10 or less, as measured in accordance with JIS C2101 under test conditions of a measurement temperature of 80°C, an applied voltage of 250 V, and a measurement time of 1 minute, from the viewpoint of providing a lubricating base oil with excellent insulating properties. ５ Ωm or more, more preferably 5.0×10 ５ Ωm or more, more preferably 1.0×10 ６ Ωm or more, more preferably 5.0×10 ６ Ωm or more, more preferably 1.0×10 ７ Ωm or more, and even more preferably 5.0×10 ７ Ωm or more, particularly preferably 1.0×10 ８ It is Ωm or more.

[0053] The flash point of the lubricating base oil of one embodiment of the present invention is preferably 154 ° C. or higher, more preferably 1160 ° C. or higher, more preferably 164 ° C. or higher, more preferably 170 ° C. or higher, even more preferably 174 ° C. or higher, even more preferably 180 ° C. or higher, even more preferably 190 ° C. or higher, even more preferably 200 ° C. or higher, even more preferably 210 ° C. or higher, particularly preferably 220 ° C. or higher, and may be 400 ° C. or lower, 380 ° C. or lower, 350 ° C. or lower, 330 ° C. or lower, 320 ° C. or lower, 310 ° C. or lower, or 300 ° C. or lower. In this specification, the flash point means a value measured by the Cleveland Open Method (COC method) in accordance with JIS K2265-4 (Method of determining flash point - Part 4: Cleveland Open Method).

[0054] A test nitrile rubber is immersed in the lubricating base oil of one embodiment of the present invention, and the volume change of the test nitrile rubber is measured under conditions of 150°C for 72 hours in accordance with JIS K6258, and from the viewpoint of obtaining a lubricating base oil with good rubber compatibility, the volume change of the test nitrile rubber is preferably less than 6%, more preferably 5% or less, even more preferably 4% or less, still more preferably 3% or less, and particularly preferably 2% or less. In this specification, the volume change of the test nitrile rubber means a value measured and calculated by the method described in the examples.

[0055] [Constitution of Lubricating Oil Composition] The lubricating oil composition of one embodiment of the present invention contains the lubricating base oil of one embodiment of the present invention described above. The lubricating oil composition of one embodiment of the present invention may further contain lubricating oil additives, specifically, one or more lubricating oil additives selected from pour point depressants, viscosity index improvers, antioxidants, extreme pressure agents, metal detergents, ashless dispersants, metal deactivators, friction modifiers, rust inhibitors, and antifoaming agents. These lubricating oil additives may be used alone or in combination of two or more.

[0056] The content of each of these lubricating oil additives can be adjusted as appropriate within a range that does not impair the effects of the present invention, but is typically 0.001 to 15 mass %, preferably 0.005 to 10 mass %, and more preferably 0.01 to 5 mass %, for each additive, based on the total amount (100 mass %) of the lubricating oil composition.

[0057] Furthermore, the lubricating oil composition of one embodiment of the present invention may have limited contents of the lubricating oil additives, and the content of each of the lubricating oil additives may be less than 5.0 mass%, less than 2.0 mass%, less than 1.0 mass%, less than 0.1 mass%, less than 0.01 mass%, less than 0.001 mass%, less than 0.0001 mass%, or less than 0.00001 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0058] Furthermore, the content of lubricating oil additives, including other additives (surfactants, colorants, etc.) other than those mentioned above, may be limited. The content of the lubricating oil additives to be limited may be, independently for each additive, less than 3.0 mass%, less than 2.0 mass%, less than 1.0 mass%, less than 0.1 mass%, less than 0.01 mass%, less than 0.001 mass%, less than 0.0001 mass%, or less than 0.00001 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0059] In the lubricating oil composition of one embodiment of the present invention, the content of the lubricating base oil of one embodiment of the present invention described above is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, still more preferably 80 mass% or more, particularly preferably 90 mass% or more, and may even be 93 mass% or more, 95 mass% or more, 96 mass% or more, 97 mass% or more, 98 mass% or more, or 99 mass% or more.

[0060] [Pour Point Depressant] Examples of pour point depressants used in one embodiment of the present invention include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, polyalkylstyrenes, etc. These pour point depressants may be used alone or in combination of two or more.

[0061] [Viscosity Index Improver] Examples of viscosity index improvers used in one embodiment of the present invention include polymers such as non-dispersant polymethacrylate, dispersant polymethacrylate, olefin copolymers (e.g., ethylene-propylene copolymers, etc.), dispersant olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers, etc.). These viscosity index improvers may be used alone or in combination of two or more. The weight average molecular weight (Mw) of the viscosity index improver used in one embodiment of the present invention may be 5,000 or more, 7,000 or more, 10,000 or more, 15,000 or more, or 20,000 or more, or may be 1,000,000 or less, 700,000 or less, 500,000 or less, 300,000 or less, 200,000 or less, 100,000 or less, or 50,000 or less.

[0062] [Antioxidant] Examples of antioxidants used in one embodiment of the present invention include amine-based antioxidants such as alkylated diphenylamine, phenylnaphthylamine, and alkylated phenylnaphthylamine; and phenol-based antioxidants such as 2,6-di-t-butylphenol, 4,4'-methylenebis(2,6-di-t-butylphenol), isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate. These antioxidants may be used alone or in combination of two or more. In the lubricating oil composition of one embodiment of the present invention, it is preferable to use an amine-based antioxidant in combination with a phenol-based antioxidant.

[0063] [Extreme Pressure Agent (Antiwear Agent)] Examples of the extreme pressure agent (antiwear agent) used in one embodiment of the present invention include sulfur-containing compounds such as zinc dithiophosphate; phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and their amine salts or metal salts; and sulfur- and phosphorus-containing compounds such as thiophosphites, thiophosphates, thiophosphonates, and their amine salts or metal salts. These extreme pressure agents may be used alone or in combination of two or more.

[0064] [Metallic Detergent] The metallic detergent used in one embodiment of the present invention includes metal salts such as metal sulfonates, metal salicylates, and metal phenates. The metal atom constituting the metal salt is preferably a metal atom selected from alkali metals and alkaline earth metals, more preferably sodium, calcium, magnesium, or barium, and even more preferably calcium. These metallic detergents may be used alone or in combination of two or more.

[0065] In the lubricating oil composition of one embodiment of the present invention, the metallic detergent preferably comprises one or more selected from calcium sulfonate, calcium salicylate, and calcium phenate, and more preferably comprises calcium sulfonate. The calcium sulfonate content is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, and still more preferably 80 to 100 mass%, based on the total amount (100 mass%) of metallic detergents contained in the lubricating oil composition.

[0066] The base number of the metallic detergent is preferably 0 to 600 mgKOH / g. However, in the lubricating oil composition of one embodiment of the present invention, the metallic detergent is preferably an overbased metallic detergent having a base number of 100 mgKOH / g or more. The base number of the overbased metallic detergent is 100 mgKOH / g or more, preferably 150 to 500 mgKOH / g, and more preferably 200 to 450 mgKOH / g. In this specification, "base number" refers to the base number measured by the perchloric acid method in accordance with JIS K2501:2003 "Petroleum products and lubricants - Test method for neutralization number".

[0067] [Ashless Dispersant] Examples of the ashless dispersant used in one embodiment of the present invention include boron-free succinimides such as boron-free alkenyl succinimides, boron-containing succinimides such as boron-containing alkenyl succinimides, benzylamines, boron-containing benzylamines, succinic acid esters, fatty acids, or mono- or di-carboxylic acid amides represented by succinic acid, etc. These ashless dispersants may be used alone or in combination of two or more.

[0068] [Metal Deactivator] Examples of the metal deactivator used in one embodiment of the present invention include benzotriazole-based compounds, tolyltriazole-based compounds, imidazole-based compounds, pyrimidine-based compounds, etc. These metal deactivators may be used alone or in combination of two or more.

[0069] [Friction Modifier] Examples of friction modifiers used in one embodiment of the present invention include molybdenum-based friction modifiers such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdenum acid; ashless friction modifiers such as aliphatic amines, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, and aliphatic ethers, each having at least one alkyl or alkenyl group having 6 to 30 carbon atoms in the molecule; fats and oils, amines, amides, and sulfurized esters. These friction modifiers may be used alone or in combination of two or more.

[0070] [Rust inhibitor] Examples of the rust inhibitor used in one embodiment of the present invention include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, alkyl polyoxyethylene ethers, etc. These rust inhibitors may be used alone or in combination of two or more.

[0071] [Antifoaming Agent] Examples of the antifoaming agent used in one embodiment of the present invention include silicone oil, fluorosilicone oil, fluoroalkyl ether, etc. These antifoaming agents may be used alone or in combination of two or more.

[0072] [Properties and Characteristics of Lubricating Oil Composition] The lubricating oil composition of one embodiment of the present invention contains a lubricating base oil having a natural origin index of 90 to 100%, and therefore can be a lubricating oil composition with reduced environmental impact upon disposal. Note that the lubricating oil composition of one embodiment of the present invention may have a natural origin index of less than 90% by containing a lubricating oil additive. However, from the viewpoint of providing a lubricating oil composition with reduced environmental impact upon disposal, the natural origin index of the lubricating oil composition of one embodiment of the present invention is preferably 70% or more, more preferably 80% or more, even more preferably 85% or more, even more preferably 90% or more, and particularly preferably 95% or more.

[0073] The kinematic viscosity at 40°C of the lubricating oil composition of one embodiment of the present invention is adjusted appropriately depending on the application, and is 4.0 mm ２ / s or more, 4.5mm ２ / s or more, 5.0mm ２ / s or more, 5.5mm ２ / s or more, 6.0mm ２ / s or more, 6.5mm ２ / s or more, 7.0mm ２ / s or more, 7.5mm ２ / s or more, 8.0mm ２ / s or more, 8.5mm ２ / s or more, 9.0mm ２ / s or more, 9.5mm ２ / s or more, 10.0mm ２ / s or more, 10.5mm ２ / s or more, 11.0mm ２ / s or more, 11.5mm ２ / s or more, 12.0mm ２ / s or more, 12.5mm ２ / s or more, 13.0mm ２ / s or more, 13.5mm ２ / s or more, 14.0mm ２ / s or more, 14.5mm ２ / s or more, 15.0mm ２ / s or more, 15.5mm ２ / s or more, 16.0mm ２ / s or more, 16.5mm ２ / s or more, 17.0mm ２ / s or more, 17.5mm ２ / s or more, or 18.0 mm ２ / s or more, and ２ / s or less, 90mm ２ / s or less, 80mm ２ / s or less, 70mm ２ / s or less, 60mm ２ / s or less, 50mm ２ / s or less, 40mm ２ / s or less, 35mm ２ / s or less, 30mm ２ / s or less, 25mm ２ / s or less, or 20 mm ２ / s or less.

[0074] The kinematic viscosity at 100°C of the lubricating oil composition of one embodiment of the present invention is adjusted appropriately depending on the application, and is 1.0 mm ２ / s or more, 1.5mm ２ / s or more, 2.0mm ２ / s or more, 2.5mm ２ / s or more, 2.7mm ２ / s or more, 3.0mm ２ / s or more, 3.1mm ２ / s or more, 3.2mm ２ / s or more, 3.3mm ２ / s or more, 3.4mm ２ / s or more, 3.5mm ２ / s or more, 3.6mm ２ / s or more, 3.7mm ２ / s or more, 3.8mm ２ / s or more, 3.9 mm ２ / s or more, 4.0mm ２ / s or more, 4.1mm ２ / s or more, or 4.2 mm ２ / s or more, and 10.0 mm ２ / s or less, 9.5mm ２ / s or less, 9.0mm ２ / s or less, 8.5mm ２ / s or less, 8.0mm ２ / s or less, 7.5mm ２ / s or less, 7.0mm ２ / s or less, 6.5mm ２ / s or less, 6.0mm ２ / s or less, 5.5mm２ / s or less, 5.0mm ２ / s or less, or 4.5 mm ２ / s or less.

[0075] The viscosity index of the lubricating oil composition of one embodiment of the present invention is preferably 70 or more, 80 or more, 85 or more, 90 or more, 95 or more, 100 or more, 105 or more, 110 or more, 115 or more, 120 or more, 125 or more, 130 or more, 135 or more, 140 or more, or 145 or more.

[0076] The pour point of the lubricating oil composition of one embodiment of the present invention is preferably 0°C or lower, more preferably -10°C or lower, more preferably -20°C or lower, even more preferably -30°C or lower, even more preferably -35°C or lower, still more preferably -40°C or lower, even more preferably -45°C or lower, and particularly preferably -50°C or lower.

[0077] The lubricating oil composition of one embodiment of the present invention preferably has a volume resistivity of 1.0×10 or less, measured in accordance with JIS C2101 under test conditions of a measurement temperature of 80° C., an applied voltage of 250 V, and a measurement time of 1 minute. ５ Ωm or more, more preferably 5.0×10 ５ Ωm or more, more preferably 1.0×10 ６ Ωm or more, more preferably 5.0×10 ６ Ωm or more, and even more preferably 1.0×10 ７ Ωm or more, particularly preferably 2.0×10 ７ It is Ωm or more.

[0078] The flash point of the lubricating oil composition of one embodiment of the present invention is preferably 154°C or higher, more preferably 1160°C or higher, more preferably 164°C or higher, more preferably 170°C or higher, even more preferably 174°C or higher, even more preferably 180°C or higher, still more preferably 190°C or higher, still more preferably 200°C or higher, and particularly preferably 210°C or higher, and may be 400°C or lower, 380°C or lower, 350°C or lower, 330°C or lower, 320°C or lower, 310°C or lower, or 300°C or lower.

[0079] A test nitrile rubber is immersed in the lubricating oil composition of one embodiment of the present invention, and the volume change rate of the test nitrile rubber, measured in accordance with JIS K6258 at 150°C for 72 hours, is preferably less than 12%, more preferably 10% or less, even more preferably 8% or less, still more preferably 4% or less, particularly preferably 2% or less, and is also preferably 0% or more, more preferably more than 0%, and even more preferably 0.1% or more.

[0080] [Uses of Lubricating Oil Composition] A lubricating oil composition according to a preferred embodiment of the present invention is a lubricating oil composition that reduces the environmental impact upon disposal, yet has various excellent lubricating properties. In consideration of these properties, the lubricating oil composition according to one embodiment of the present invention can be suitably used for lubrication of mechanisms such as torque converters, wet clutches, gear bearing mechanisms, oil pumps, and hydraulic control mechanisms, which are incorporated into various devices such as electric drive units, engines, transmissions, reducers, compressors, and hydraulic systems. Furthermore, due to its excellent cooling and insulating properties, it can also be suitably used for cooling and insulating motors and batteries. Among these, the lubricating oil composition according to one embodiment of the present invention is preferably used for cooling and insulating motors and batteries, gear bearing mechanisms, or oil pumps.

[0081] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. The methods for measuring or calculating various properties are as follows.

[0082] (1) Natural origin index: Calculated in accordance with ISO 16128. (2) Kinematic viscosity and viscosity index: Measured and calculated in accordance with JIS K2283:2000. (3) Pour point: Measured in accordance with JIS K2269. (4) Volume resistivity: Measured in accordance with JIS C2101 under test conditions of a measurement temperature of 80°C, an applied voltage of 250V, and a measurement time of 1 minute. (5) Flash point: Measured by the Cleveland Open Method (COC method) in accordance with JIS K2265-4 (Determination of flash point - Part 4: Cleveland Open Method). (6) Volume change rate of nitrile rubber: A rubber immersion test was conducted in accordance with JIS K6258. Specifically, a test specimen of nitrile rubber (manufactured by NOK Corporation, product name "A305") was immersed in the lubricating base oil to be measured at an immersion temperature of 120°C for 72 hours. The volumes of the test pieces were measured before and after the test, and the volume change rate was calculated using the following formula: [Volume change rate (%)] = ([Volume of test piece after test] - [Volume of test piece before test]) / [Volume of test piece before test] x 100

[0083] Examples 1 to 5, Comparative Examples 1 to 7, Reference Examples 1 to 2 Lubricating base oils were prepared by combining diester compounds, ester compounds, hydrocarbon compounds, and mineral oils in the types and amounts shown in Tables 1 and 2. Next, 5.0 parts by mass of an additive mixture was added to 95.0 parts by mass of the lubricating base oil to prepare lubricating oil compositions. Various physical property values ​​of the prepared lubricating base oils and lubricating oil compositions were measured according to the methods described above. The results are shown in Tables 1 and 2. Details of each component used in preparing the lubricating base oils and lubricating oil compositions are as follows:

[0084] <Diester compounds> "Propylene glycol dicaprylate": a diester compound represented by R in the general formula (a-2) obtained from caprylic acid (derived from oil palm) and 1,2-propanediol (derived from corn). １ and R ２is an n-heptyl group (a C7 linear alkyl group). Natural origin index = 100%. "Propylene glycol dicaprate": a diester compound having 19 carbon atoms, in which R in the general formula (a-2) is an n-heptyl group (a C7 linear alkyl group). Natural origin index = 100%. １ and R ２ A diester compound with 23 carbon atoms, in which the n-nonyl group (C9 linear alkyl group) is used. Natural origin index = 100%. - "Bis(2-ethylhexyl) sebacate": A diester compound with 26 carbon atoms, produced from sebacic acid (derived from castor beans) and 2-ethylhexanol (derived from petroleum). Natural origin index = 39%. - "Dibutyl sebacate": A diester compound with 18 carbon atoms, produced from sebacic acid (derived from castor beans) and butanol (derived from petroleum). Natural origin index = 54%. <Ester compounds> - "2-ethylhexyl laurate": A monoester compound with 20 carbon atoms, produced from lauric acid (derived from oil palm) and 2-ethylhexanol (derived from petroleum). Natural origin index = 59%.・ "Glyceryl tricaprylate": A triester compound with 21 carbon atoms produced from caprylic acid (derived from oil palm) and glycerin (derived from oil palm), natural origin index = 100%. <Hydrocarbon compounds> ・ "Hydrogenated reaction product of octadecene and hexadecene": A saturated hydrocarbon compound with approximately 34 carbon atoms produced by hydrogenating the reaction product of octadecene (derived from oil palm) and hexadecene (derived from oil palm). Natural origin index = 100%, kinematic viscosity at 100°C = 4.4 mm ２ / s. <Mineral oil> ・ "60N mineral oil": 40 ° C. kinematic viscosity = 7.9 mm ２ / s, 100℃ kinematic viscosity = 2.3mm ２ / s, mineral oil with a viscosity index of 104. Natural origin index = 0%. "100N mineral oil": 40°C kinematic viscosity = 19.8 mm ２ / s, 100℃ kinematic viscosity = 4.3mm ２ / s, mineral oil with a viscosity index of 122. Natural origin index = 0%. <Additives> - "Additive mixture": an additive mixture obtained by diluting a pour point depressant, an antioxidant, a phosphorus-based extreme pressure agent, a sulfur-based extreme pressure agent, an ashless dispersant, a metal-based detergent, a metal deactivator, and an antifoaming agent with diluent oil (mineral oil).

[0085]

[0086]

[0087] As shown in Table 1, the lubricating base oils prepared in Examples 1 to 5 had a natural origin index of 100%, and can be said to be lubricating base oils with reduced environmental impact upon disposal. Furthermore, since the lubricating base oils and lubricating oil compositions prepared in Examples 1 to 5 contain a diester compound (A) and a hydrocarbon compound (B), they have excellent viscosity characteristics, low-temperature fluidity, insulating properties, safety due to their high flash points, and rubber compatibility, and were confirmed to have properties comparable to those of the lubricating oil compositions using mineral oil in Reference Examples 1 and 2. On the other hand, since the lubricating base oil and lubricating oil composition prepared in Comparative Example 1 did not contain a diester compound (A), the rubber contracted, resulting in poor rubber compatibility. Furthermore, since the lubricating base oils and lubricating oil compositions prepared in Comparative Examples 2 to 5 did not contain a hydrocarbon compound (B), the degree of rubber swelling was large, resulting in insufficient rubber compatibility and poor insulating properties.

Claims

1. A lubricating base oil having a natural origin index (ISO 16128) of 90 to 100% and comprising a diester compound (A) and a hydrocarbon compound (B).

2. The lubricating base oil according to claim 1, wherein the hydrocarbon compound (B) has 18 or more carbon atoms.

3. The lubricating base oil according to claim 1, wherein the hydrocarbon compound (B) has 20 or more carbon atoms.

4. The lubricating base oil according to any one of claims 1 to 3, wherein the diester compound (A) has 12 or more carbon atoms.

5. The lubricating base oil according to any one of claims 1 to 4, wherein the diester compound (A) comprises a diester compound having one or more branched chain structures.

6. The lubricating base oil according to any one of claims 1 to 5, wherein the diester compound (A) comprises a saturated diester compound.

7. The lubricating base oil according to any one of claims 1 to 6, wherein the diester compound (A) comprises a compound (A1) represented by the following general formula (a-1): (In the above formula, R １ and R ２ are each independently a hydrocarbon group. A is an alkylene group having 2 to 5 carbon atoms. R １ , R ２ and A have a total carbon number of 10 or more.

8. The lubricating base oil according to claim 7, wherein A in general formula (a-1) is a branched alkylene group.

9. R in the general formula (a-1) １ and R ２ The lubricating base oil according to claim 7 or 8, wherein each of the groups independently represents a linear alkyl group having 5 or more carbon atoms.

10. The lubricating base oil according to any one of claims 1 to 6, wherein the diester compound (A) is a compound (A11) represented by the following general formula (a-11): (In the above formula, R １ and R ２ are each independently a hydrocarbon group. １ and R ２ The total number of carbon atoms is 7 or more.

11. R in the general formula (a-11) １ and R ２ are each independently a linear alkyl group having 5 or more carbon atoms.

12. The lubricating base oil according to any one of claims 1 to 11, wherein the lubricating base oil has a pour point of 0°C or less.

13. The lubricating base oil according to any one of claims 1 to 12, wherein a test nitrile rubber is immersed in the lubricating base oil and the volume change rate of the test nitrile rubber measured in accordance with JIS K6258 at 150°C for 72 hours is 0% or more and less than 12%.

14. The lubricating base oil according to any one of claims 1 to 13, wherein the lubricating base oil has a flash point of 160°C or higher.

15. The lubricating base oil according to any one of claims 1 to 14, wherein the content ratio of component (A) to component (B) [(A) / (B)] is, in mass ratio, from 0.05 to 19.

0.

16. The lubricating base oil according to any one of claims 1 to 15, wherein the natural origin index (ISO 16128) of component (A) is 90 to 100 mass %, and the natural origin index (ISO 16128) of component (B) is 90 to 100 mass %.

17. A lubricating oil composition comprising the lubricating base oil of any one of claims 1 to 16.

18. The lubricating oil composition of claim 17, further comprising one or more lubricating oil additives selected from the group consisting of pour point depressants, viscosity index improvers, antioxidants, extreme pressure agents, metal detergents, ashless dispersants, metal deactivators, friction modifiers, rust inhibitors, and antifoaming agents.

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