Heat-treated oil composition

Abstract

To provide a heat-treated oil composition containing a sulfur compound, which is excellent in brightness and storage stability of a metal material after heat treatment such as quenching.SOLUTION: A heat-treated oil composition comprises: one or more base oils (A) selected from a group consisting of a mineral oil (A1), a synthetic oil (A2), and a vegetable oil (A3); and a sulfur compound (B). The sulfur compound (B) contains one or more selected from the group consisting of specific sulfide compounds (B1), specific sulfide compounds (B2) and specific thiazole compounds (B3).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a heat-treating oil composition. [Background technology]

[0002] Metallic materials such as steel are often subjected to heat treatments such as quenching, tempering, annealing, and normalizing to improve their properties. Among these heat treatments, quenching is a process in which a heated metallic material is immersed in a coolant to transform it into a predetermined quenched structure. Quenching makes the metallic material very hard and improves its mechanical strength.

[0003] Heat treatment oil compositions are widely used as coolants for quenching. In addition to their performance as coolants, heat treatment oil compositions are also required to maintain the surface gloss of metal materials before quenching after quenching, in order to increase the commercial value of the metal materials after quenching. In other words, heat treatment oil compositions are required to have the performance of improving the brightness of metal materials after quenching.

[0004] As such a heat treatment oil composition, for example, a heat treatment oil composition containing a condensed polycyclic aromatic compound such as anthracene has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-209422 Summary of the Invention [Problem to be solved by the invention]

[0006] It is generally said that when a heat treatment oil composition with a low sulfur content is used for quenching, the luster of the metal material after quenching decreases. In Patent Document 1, by using a heat treatment oil composition containing a condensed polycyclic aromatic compound such as anthracene, the luster is improved even for a heat treatment oil composition with a low sulfur content. Here, the heat-treated oil composition is also required to have excellent storage stability, however, Patent Document 1 does not fully consider storage stability.

[0007] Therefore, the present inventors conducted research based on the above-mentioned demands and found that a heat treatment oil composition containing a specific sulfur compound has excellent luster and storage stability of metal materials after heat treatment such as quenching.

[0008] Therefore, an object of the present invention is to provide a heat treatment oil composition containing a sulfur compound that is excellent in the luster and storage stability of metal materials after heat treatment such as quenching. [Means for solving the problem]

[0009] According to the present invention, the following [1] to [3] are provided. [1] A lubricating oil composition comprising one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3), and a sulfur compound (B), The heat treatment oil composition, wherein the sulfur compound (B) comprises one or more selected from the group consisting of sulfides (B1) represented by the following general formula (b1), sulfides (B2) represented by the following general formula (b2), and thiazoles (B3) represented by the following general formula (b3): [ka] [In the general formulas (b1) and (b2), R 11 , R 12 , R 13 , and R 14 each independently represents a substituted or unsubstituted hydrocarbon group (X), which represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formulas (b1) and (b2), L 11 , L 12 , L 13 , and L 14 each independently represents an alkylene group having 2 to 6 carbon atoms. [ka] [In the general formula (b3), R 21 represents a substituted or unsubstituted hydrocarbon group (Y), which is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 3. If n is 2 or more, there are multiple R 21 may be the same or different. In addition, when n is 2 or more, and two R 21 are adjacent to each other, the two R 21 may form a ring structure.] [2] A method of using the heat treatment oil composition according to [1] above as a quenching oil or tempering oil. [3] A method for producing a refrigerant-based oil, comprising: mixing one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3) with a sulfur compound (B); A method for producing a heat-treated oil composition, wherein the sulfur compound (B) comprises one or more compounds selected from the group consisting of sulfides (B1) represented by the following general formula (b1), sulfides (B2) represented by the following general formula (b2), and thiazoles (B3) represented by the following general formula (b3). [ka] [In the general formulas (b1) and (b2), R 11 , R 12 , R 13 , and R14 each independently represents a substituted or unsubstituted hydrocarbon group (X), which represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formulas (b1) and (b2), L 11 , L 12 , L 13 , and L 14 each independently represents an alkylene group having 2 to 6 carbon atoms. [ka] [In the general formula (b3), R 21 represents a substituted or unsubstituted hydrocarbon group (Y), which is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 3. If n is 2 or more, there are multiple R 21 may be the same or different. In addition, when n is 2 or more, and two R 21 are adjacent to each other, the two R 21 may form a ring structure.] [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a heat treatment oil composition containing a sulfur compound, which is excellent in the luster and storage stability of metal materials after heat treatment such as quenching. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 2 is a diagram showing the positions of the "edges" and "contact parts" that were visually observed for the test pieces used in the examples. [Figure 2] 1 is a photograph, substituted for a drawing, showing the state of test pieces after a quenching test using the heat treatment oil compositions of Examples 1 to 8 and Comparative Examples 1 to 3. [Figure 3] 1 is a drawing-substitute photograph showing the state of test pieces after a quenching test using the heat-treated oil compositions of Comparative Examples 4 to 5 and Examples 9 to 10 (new oil, oil after oxidative degradation for 24 hours). [Figure 4] 1 is a photograph in place of a drawing showing the state of test pieces after quenching tests using the heat-treated oil compositions of Examples 9, 11, and 12 (new oil, oil after oxidative degradation for 24 hours, and oil after oxidative degradation for 48 hours). [Figure 5] 1 is a photograph substituting for a drawing showing the state of test pieces after a quenching test using the heat treatment oil compositions of Comparative Example 6 and Examples 13 to 14. DETAILED DESCRIPTION OF THE INVENTION

[0012] In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), the lower and upper limits described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60." Furthermore, unless otherwise specified, the numerical range "lower limit to upper limit" described in this specification means that the range is equal to or greater than the lower limit and equal to or less than the upper limit. In this specification, the numerical values in the examples are numerical values that can be used as upper or lower limit values. In this specification, "kinematic viscosity at 40°C" is also referred to as "40°C kinematic viscosity."

[0013] [Embodiments of heat-treated oil composition] The heat-treated oil composition of this embodiment contains one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3), and a sulfur compound (B). In the heat-treated oil composition of this embodiment, the sulfur compound (B) comprises one or more compounds selected from the group consisting of sulfides (B1) represented by the following general formula (b1), sulfides (B2) represented by the following general formula (b2), and thiazoles (B3) represented by the following general formula (b3): [ka] [In the general formulas (b1) and (b2), R 11 , R 12 , R 13 , and R 14 each independently represents a substituted or unsubstituted hydrocarbon group (X), which represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formulas (b1) and (b2), L 11 , L 12 , L 13 , and L 14 each independently represents an alkylene group having 2 to 6 carbon atoms. [ka] [In the general formula (b3), R 21 represents a substituted or unsubstituted hydrocarbon group (Y), which is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 3. If n is 2 or more, there are multiple R 21 may be the same or different. In addition, when n is 2 or more, and two R21 are adjacent to each other, the two R 21 may form a ring structure.]

[0014] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that specific sulfides having an ester structure and specific thiazoles having a thiazole skeleton can solve the above-mentioned problems. Based on this finding, the present inventors have conducted further research and have completed the present invention.

[0015] The heat-treated oil composition of this embodiment may be composed only of base oil (A) and sulfur compound (B), but may also contain other components other than base oil (A) and sulfur compound (B) as long as the effects of the present invention are not impaired. In this embodiment, the total content of the base oil (A) and the sulfur compound (B) is preferably 75% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, even more preferably 85% by mass to 100% by mass, still more preferably 90% by mass to 100% by mass, and even more preferably 95% by mass to 100% by mass, based on the total amount of the heat-treated oil composition.

[0016] Each component contained in the heat-treated oil composition of the present invention will be described in detail below.

[0017] <Base oil (A)> The heat-treated oil composition of this embodiment contains a base oil (A). The base oil (A) is one or more selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3). The mineral oil (A1), the synthetic oil (A2), and the vegetable oil (A3) will be described in detail below.

[0018] (Mineral oil (A1)) As the mineral oil (A1), any mineral oil commonly used in heat treatment oil compositions can be used without any particular limitation. Specific examples of the mineral oil (A1) include atmospheric residues obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate crude oil, and naphthenic crude oil; distillates obtained by vacuum distillation of these atmospheric residues; mineral oils obtained by subjecting the distillates to one or more treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining; and wax isomerized mineral oils.

[0019] The mineral oil (A1) may also be a highly refined mineral oil whose sulfur content has been reduced by subjecting it to a refining treatment including at least one treatment selected from hydrocracking and hydrorefining. The sulfur content of the highly refined mineral oil is preferably less than 10 ppm by mass, more preferably less than 5 ppm by mass, and even more preferably less than 3 ppm by mass, based on the total amount of the highly refined mineral oil.

[0020] The mineral oil (A1) may also be bright stock. In this specification, "bright stock" refers to a high-viscosity mineral oil (kinematic viscosity at 40°C: 350mm) obtained by vacuum distilling atmospheric residue obtained by atmospheric distillation of crude oil such as paraffinic crude oil, intermediate crude oil, naphthenic crude oil, etc., and then deasphalting the distillate to obtain deasphalted oil, which is then subjected to one or more refining treatments selected from solvent refining, hydrorefining, etc. 2 / s~550mm 2 / s). Here, the bright stock may be bright stock (hydrorefined product) with a low sulfur content, or may be bright stock with a high sulfur content. Low sulfur bright stock preferably has a sulfur content of less than 10 ppm by mass, more preferably less than 5 ppm by mass, and even more preferably less than 3 ppm by mass, based on the total amount of bright stock. Furthermore, bright stock with a high sulfur content preferably has a sulfur content of 0.30% by mass to 2.0% by mass based on the total amount of bright stock. Preferably, bright stock with a low sulfur content is classified as API Group II, and bright stock with a high sulfur content is classified as API Group I.

[0021] In order to increase the sulfur content and improve the luster of metal materials after heat treatment such as quenching, heat treatment oil compositions may contain mineral oils containing bright stock with a high sulfur content (sulfur content of 0.30% by mass to 2.0% by mass based on the total amount of bright stock). However, as a result of studies by the present inventors, it was found that heat treatment oil compositions containing mineral oils containing bright stock with a high sulfur content may reduce the luster of metal materials after heat treatment such as quenching, and that the luster of metal materials after heat treatment such as quenching is likely to decrease particularly when the heat treatment temperature is high, such as 900°C or higher (particularly 950°C or higher). According to the research conducted by the present inventors, it has been confirmed that even when a mineral oil (A1) containing bright stock with a high sulfur content is used as the base oil (A) contained in the heat treatment oil composition, the luster of the metal material after heat treatment such as quenching can be improved by blending a sulfur compound (B) (preferably, one or more selected from sulfides (B1) and thiazoles (B3)).

[0022] In the heat-treated oil composition of this embodiment, bright stock having a high sulfur content may be blended with base oil (A) depending on the desired viscosity and sulfur content required for the heat-treated oil composition. When base oil (A) contains high-sulfur bright stock, the content of high-sulfur bright stock is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on the total amount of base oil (A). From the viewpoint of improving the luster of metal materials after heat treatment such as quenching, the content is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the content is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and even more preferably 3 to 10% by mass. In the heat-treated oil composition of this embodiment, low-sulfur bright stock may be blended with base oil (A) depending on the desired viscosity required for the heat-treated oil composition. When base oil (A) contains low-sulfur bright stock, the content of low-sulfur bright stock may be 1% by mass to 100% by mass based on the total amount of base oil (A).

[0023] The mineral oil (A1) may be used alone or in combination of two or more kinds.

[0024] (Synthetic oil (A2)) As the synthetic oil (A2), any synthetic oil commonly used in heat treatment oil compositions can be used without any particular limitation. Specific examples of synthetic oils (A2) include poly-α-olefins, polyphenyl ethers, alkylbenzenes, alkylnaphthalenes, polyphenyl hydrocarbons, ester oils (e.g., fatty acid esters of polyhydric alcohols such as neopentyl glycol, trimethylolpropane, and pentaerythritol), glycol-based synthetic oils, and GTL base oils obtained by isomerizing wax produced from natural gas by the Fischer-Tropsch process or the like (GTL wax (Gas To Liquids WAX)). Among these, GTL base oils are preferred. The synthetic oil (A2) may be used alone or in combination of two or more.

[0025] (Vegetable oil (A3)) As the vegetable oil (A3), any vegetable oil commonly used in heat-treated oil compositions can be used without any particular limitation. Specific examples of the vegetable oil (A3) include linseed oil, safflower oil, sunflower oil, soybean oil, corn oil, cottonseed oil, sesame oil, olive oil, castor oil, peanut oil, coconut oil, palm kernel oil, palm oil, coconut oil, rapeseed oil, and rice bran oil. The vegetable oil (A3) may be used alone or in combination of two or more.

[0026] (Preferred embodiment of base oil (A)) In this embodiment, the base oil (A) may be at least one selected from the group consisting of mineral oil (A1), synthetic oil (A2), and vegetable oil (A3), but is preferably at least one selected from the group consisting of mineral oil (A1) and synthetic oil (A2). Furthermore, the base oil (A) preferably contains a mineral oil (A1). When the base oil (A) contains a mineral oil (A1), the content of the mineral oil (A1) is preferably 20% by mass to 100% by mass, more preferably 30% by mass to 100% by mass, even more preferably 40% by mass to 100% by mass, still more preferably 50% by mass to 100% by mass, even more preferably 60% by mass to 100% by mass, still more preferably 70% by mass to 100% by mass, even more preferably 80% by mass to 100% by mass, and still more preferably 90% by mass to 100% by mass, based on the total amount of the base oil (A).

[0027] (Kinematic viscosity of base oil (A) at 40°C) The kinematic viscosity at 40°C of the base oil (A) used in this embodiment is preferably 5mm 2 / s~600mm 2 / s, more preferably 6 mm 2 / s~570mm 2 / s, more preferably 7 mm 2 / s~540mm 2 / s, even more preferably 8 mm 2 / s~520mm 2 / s, and even more preferably 9 mm 2 / s~500mm 2 / s. The kinematic viscosity of base oil (A) at 40°C is 5mm 2On the other hand, if the kinematic viscosity at 40°C of the base oil (A) is 600 mm / s or more, it is easy to obtain a heat-treated oil composition that suppresses the generation of oily smoke. 2 / s or less, it is easy to obtain a heat treatment oil composition with good cooling performance. In this specification, the kinematic viscosity at 40°C is a value measured in accordance with JIS K2283:2000. In addition, in consideration of ease of adjusting the 40°C kinematic viscosity of the base oil (A), it is preferable to use a mixture of multiple base oils with different 40°C kinematic viscosities in the heat-treated oil composition of this embodiment.

[0028] (Base oil (A) content) In the heat-treated oil composition of this embodiment, the content of the base oil (A) is preferably 80.0 mass% or more, more preferably 82.0 mass% or more, and even more preferably 83.0 mass% or more, based on the total amount of the heat-treated oil composition, and is preferably 99.99 mass% or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the content is preferably 80.0 mass % to 99.99 mass %, more preferably 82.0 mass % to 99.99 mass %, and even more preferably 83.0 mass % to 99.99 mass %.

[0029] <Sulfur compounds (B)> The heat-treated oil composition of this embodiment contains a sulfur compound (B). If the heat treatment oil composition does not contain the sulfur compound (B), the luster of the metal material after heat treatment such as quenching cannot be improved. In this embodiment, the sulfur compound (B) includes one or more selected from the group consisting of sulfides (B1), sulfides (B2), and thiazoles (B3). In this embodiment, the sulfur compound (B) may consist of only one or more selected from the group consisting of sulfides (B1), sulfides (B2), and thiazoles (B3), but may also contain sulfur compounds other than the sulfides (B1), sulfides (B2), and thiazoles (B3) within a range that does not impair the effects of the present invention. In the present embodiment, the content of one or more compounds selected from the group consisting of sulfides (B1), sulfides (B2), and thiazoles (B3) is preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, and still more preferably 95% by mass to 100% by mass, based on the total amount of the sulfur compounds (B). The sulfides (B1), the sulfides (B2), and the thiazoles (B3) will be described in detail below.

[0030] (Sulfides (B1) and Sulfides (B2)) The sulfides (B1) are compounds represented by the following general formula (b1). The sulfides (B2) are compounds represented by the following general formula (b2). [ka]

[0031] In the general formulas (b1) and (b2), R 11 , R 12 , R 13 , and R 14 each independently represents a substituted or unsubstituted hydrocarbon group (X). When the hydrocarbon group (X) has a substituent, examples of the substituent include a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a hydroxyl group, an amino group, a nitro group, a carboxyl group, and a halogen atom. The monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms is preferably a linear or branched alkyl group having 3 to 10 carbon atoms, and more preferably a branched alkyl group having 3 to 10 carbon atoms. The halogen atom is, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and is preferably a chlorine atom. When the hydrocarbon group (X) has a substituent, the number of the substituent may be one or more. When the hydrocarbon group (X) has a plurality of substituents, the plurality of substituents may be the same or different.

[0032] In the general formulae (b1) and (b2), the hydrocarbon group (X) represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. The number of carbon atoms in the hydrocarbon group (X) does not include the number of carbon atoms in the substituents that the hydrocarbon group (X) may have. If the carbon number of the group that can be selected as the hydrocarbon group (X) exceeds 20, the luster of the metal material after heat treatment such as quenching may be deteriorated, and the storage stability may also be deteriorated. Among these, from the viewpoint of making it easier to exert the effects of the present invention, an aryl group having 6 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms is preferred. That is, in the general formula (b1), R 11 and R 12 Among these, at least one hydrocarbon group (X) is preferably an aryl group having 6 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms, and more preferably both are aryl groups having 6 to 20 carbon atoms or arylalkyl groups having 7 to 20 carbon atoms. In addition, in the general formula (b2), R 13 and R 14 Among these, at least one hydrocarbon group (X) is preferably an aryl group having 6 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms, and more preferably both are aryl groups having 6 to 20 carbon atoms or arylalkyl groups having 7 to 20 carbon atoms. Furthermore, when the hydrocarbon group (X) is an aryl group having 6 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms, the hydrocarbon group (X) preferably has a substituent. Preferred substituents include a branched alkyl group having 3 to 10 carbon atoms and a hydroxyl group, and it is more preferable that the hydrocarbon group (X) has both of these substituents. Even more preferably, the hydrocarbon group (X) has two branched alkyl groups having 3 to 10 carbon atoms and one hydroxyl group.

[0033] Examples of alkyl groups having 1 to 20 carbon atoms that can be selected as the hydrocarbon group (X) include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an icosyl group. The alkyl group may be linear or branched. In order to more easily exert the effects of the present invention, the alkyl group preferably has 6 to 20 carbon atoms, more preferably 8 to 20 carbon atoms, and even more preferably 10 to 20 carbon atoms.

[0034] Examples of alkenyl groups having 2 to 20 carbon atoms that can be selected as the hydrocarbon group (X) include ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, and icocenyl groups. The alkenyl group may be linear or branched. In order to more easily exert the effects of the present invention, the alkenyl group preferably has 6 to 20 carbon atoms, more preferably 8 to 20 carbon atoms, and even more preferably 10 to 20 carbon atoms.

[0035] Examples of the cycloalkyl group having 3 to 20 carbon atoms that can be selected as the hydrocarbon group (X) include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. The "3 to 20 carbon atoms" in the "cycloalkyl group having 3 to 20 carbon atoms" means that the group has 3 to 20 ring carbon atoms. In order to more easily exert the effects of the present invention, the cycloalkyl group preferably has 4 to 16 carbon atoms, more preferably 5 to 10 carbon atoms, and even more preferably 5 to 6 carbon atoms.

[0036] Examples of the cycloalkenyl group having 3 to 20 carbon atoms that can be selected as the hydrocarbon group (X) include a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. The "3 to 20 carbon atoms" in the "cycloalkenyl group having 3 to 20 carbon atoms" means that the "cycloalkenyl group has 3 to 20 ring carbon atoms." In order to more easily exert the effects of the present invention, the cycloalkenyl group preferably has 4 to 16 carbon atoms, more preferably 5 to 10 carbon atoms, and even more preferably 5 to 6 carbon atoms.

[0037] Examples of the cycloalkylalkyl group having 4 to 20 carbon atoms that can be selected as the hydrocarbon group (X) include a cyclopropylmethyl group, a cyclopropylethyl group, a cyclopropylpropyl group, a cyclopropylbutyl group, a cyclobutylmethyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylpropyl group, a cyclohexylmethyl group, a cyclohexylethyl group, and a cyclohexylpropyl group. The cycloalkylalkyl group is a group represented by the following general formula (c1), in which one of the hydrogen atoms of an alkyl group is substituted with a cycloalkyl group. [ka] In the above general formula (c1), the circle represents a cycloalkyl group, and R 31 is an alkylene group. The wavy line represents the bonding position to a carbon atom in the above general formula (b1) or the bonding position to an oxygen atom in the above general formula (b2). The "4 to 20 carbon atoms" in the "cycloalkylalkyl group having 4 to 20 carbon atoms" refers to the number of ring carbon atoms in the cycloalkyl group and the number of alkylene groups (R 31 ) and the total number of carbon atoms. To more easily exert the effects of the present invention, the cycloalkyl group constituting the cycloalkylalkyl group preferably has 4 to 16 carbon atoms (number of ring carbon atoms), more preferably 5 to 10, and even more preferably 5 to 6 carbon atoms. In order to more easily exert the effects of the present invention, the alkylene group constituting the cycloalkylalkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 2 to 3 carbon atoms.

[0038] Examples of cycloalkenylalkyl groups having 4 to 20 carbon atoms that can be selected as the hydrocarbon group (X1) include a cyclopropenylmethyl group, a cyclopropenylethyl group, a cyclopropenylpropyl group, a cyclopropenylbutyl group, a cyclobutenylmethyl group, a cyclopentenylmethyl group, a cyclopentenylethyl group, a cyclopentenylpropyl group, a cyclohexenylmethyl group, a cyclohexenylethyl group, and a cyclohexenylpropyl group. The cycloalkenylalkyl group is a group represented by the following general formula (c2), in which one of the hydrogen atoms of an alkyl group has been substituted with a cycloalkenyl group. [ka] In the above general formula (c2), the circle represents a cycloalkenyl group, and R 32 is an alkylene group. The wavy line represents the bonding position to a carbon atom in the above general formula (b1) or the bonding position to an oxygen atom in the above general formula (b2). The "4 to 20 carbon atoms" in the "cycloalkenylalkyl group having 4 to 20 carbon atoms" refers to the number of ring carbon atoms of the cycloalkenyl group and the number of alkylene groups (R 32 ) and the total number of carbon atoms. To more easily exert the effects of the present invention, the cycloalkenyl group constituting the cycloalkenylalkyl group preferably has 4 to 16 carbon atoms (number of ring carbon atoms), more preferably 5 to 10, and even more preferably 5 to 6 carbon atoms. In order to more easily exert the effects of the present invention, the alkylene group constituting the cycloalkenylalkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 2 to 3 carbon atoms.

[0039] Examples of aryl groups having 6 to 20 carbon atoms that can be selected as the hydrocarbon group (X1) include a phenyl group, a biphenyl group, a naphthyl group, a phenanthryl group, a triphenylenyl group, a fluorenyl group, an anthryl group, a benzochrysenyl group, and a fluoranthenyl group. The "6 to 20 carbon atoms" in the "aryl group having 6 to 20 carbon atoms" means that the ring has 6 to 20 carbon atoms. In order to more easily exert the effects of the present invention, the aryl group preferably has 6 to 16 carbon atoms, more preferably 6 to 10 carbon atoms, and even more preferably 6 carbon atoms.

[0040] Examples of the arylalkyl group having 7 to 20 carbon atoms that can be selected as the hydrocarbon group (X1) include a phenylmethyl group, a phenylethyl group, a phenylpropyl group, a biphenylmethyl group, a biphenylethyl group, a biphenylpropyl group, a naphthylmethyl group, a naphthylethyl group, a naphthylpropyl group, a phenanthrylmethyl group, a phenanthrylethyl group, a phenanthrylpropyl group, a triphenylenylmethyl group, a triphenylenylethyl group, a triphenylenylpropyl group, a fluorenylmethyl group, a fluorenylethyl group, a fluorenylpropyl group, an anthrylmethyl group, an anthrylethyl group, an anthrylpropyl group, a benzochrysenylmethyl group, a benzochrysenylethyl group, a benzochrysenylpropyl group, a fluoranthenylmethyl group, a fluoranthenylethyl group, and a fluoranthenylpropyl group. The arylalkyl group is a group represented by the following general formula (c3), in which one of the hydrogen atoms of an alkyl group is substituted with an aryl group. [ka] In the above general formula (c3), the double circle represents an aryl group, and R 33 is an alkylene group. The wavy line represents the bonding position to a carbon atom in the above general formula (b1) or the bonding position to an oxygen atom in the above general formula (b2). The "7 to 20 carbon atoms" in the "arylalkyl group having 7 to 20 carbon atoms" refers to the number of ring carbon atoms in the aryl group and the number of alkylene groups (R 33 ) and the total number of carbon atoms. In order to more easily exert the effects of the present invention, the aryl group constituting the arylalkyl group preferably has 6 to 16 carbon atoms (number of ring carbon atoms), more preferably 6 to 10, and even more preferably 6. In order to more easily exert the effects of the present invention, the alkylene group constituting the arylalkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 2 to 3 carbon atoms.

[0041] In the above general formulas (b1) and (b2), L 11 , L 12 , L 13 , and L 14 each independently represents an alkylene group having 2 to 6 carbon atoms. If the number of carbon atoms in the alkylene group is 1, the luster of the heat treatment oil composition will be deteriorated. If the number of carbon atoms in the alkylene group is 7 or more, the compounds represented by the general formulas (b1) and (b2) will be difficult to synthesize and therefore difficult to obtain. The alkylene group preferably has 2 to 5 carbon atoms, more preferably 2 to 4 carbon atoms, and even more preferably 2 to 3 carbon atoms, from the viewpoint of making it easier to exhibit the effects of the present invention.

[0042] Here, from the viewpoint of improving brilliance, it is preferable to use the sulfides (B1) among the sulfides (B1) and the sulfides (B2). In order to more easily exert the effects of the present invention, the sulfide (B1) preferably contains a compound represented by the following general formula (b1-1). From the viewpoint of further enhancing the effects of the present invention, the content of the compound represented by the following general formula (b1-1) is preferably 70% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, and still more preferably 95% by mass to 100% by mass, based on the total amount of the sulfides (B1). [ka]

[0043] In the general formula (b1-1), R 16 and R 17 each independently represents an alkylene group having 1 to 6 carbon atoms. The alkylene group preferably has 2 to 5 carbon atoms, more preferably 2 to 4 carbon atoms, and even more preferably 2 to 3 carbon atoms, from the viewpoint of making it easier to exhibit the effects of the present invention.

[0044] In the general formula (b1-1), L 11 and L 12 As in the general formula (b1), each independently represents an alkylene group having 2 to 6 carbon atoms. If the alkylene group has 1 carbon atom, the luster of the heat treatment oil composition will be impaired. If the alkylene group has 7 or more carbon atoms, the compound represented by the general formula (b1-1) will be difficult to synthesize and therefore difficult to obtain. The alkylene group preferably has 2 to 5 carbon atoms, more preferably 2 to 4 carbon atoms, and even more preferably 2 to 3 carbon atoms, from the viewpoint of making it easier to exhibit the effects of the present invention.

[0045] In the general formula (b1-1), R 18 and R 19 each independently represents an alkyl group having 1 to 10 carbon atoms or a hydroxyl group. From the viewpoint of making it easier to exert the effects of the present invention, the alkyl group is preferably a linear or branched alkyl group having 3 to 10 carbon atoms, and more preferably a branched alkyl group having 3 to 10 carbon atoms.

[0046] In the general formula (b1-1), m1 represents an integer of 0 to 5. m1 is preferably 1 to 4, more preferably 2 or 4, and even more preferably 3. If m1 is 2 or more, there are multiple R 18 may be the same or different. If m1 is 3, there are multiple R18 It is preferable that one of them is a hydroxyl group and the remaining two are alkyl groups having 1 to 10 carbon atoms. In addition, the alkyl groups are preferably branched alkyl groups having 3 to 10 carbon atoms.

[0047] In the general formula (b1-1), m2 represents an integer of 0 to 5. m2 is preferably 1 to 4, more preferably 2 or 4, and even more preferably 3. If m2 is 2 or more, there are multiple R 19 may be the same or different. If m2 is 3, there are multiple R 19 It is preferable that one of them is a hydroxyl group and the remaining two are alkyl groups having 1 to 10 carbon atoms. In addition, the alkyl groups are preferably branched alkyl groups having 3 to 10 carbon atoms.

[0048] Specific examples of the sulfides (B1) include 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Specific examples of the sulfides (B2) include didodecyl 3,3'-thiodipropionate, dioctadecyl 3,3'-thiodipropionate, and ditetradecyl 3,3'-thiodipropionate.

[0049] The sulfides (B1) may be used alone or in combination of two or more. The sulfides (B2) may be used singly or in combination of two or more. When the sulfides (B1) and the sulfides (B2) are used in combination, one or more selected from the sulfides (B1) and one or more selected from the sulfides (B2) may be used in combination.

[0050] (Thiazoles (B3)) The thiazoles (B3) are compounds represented by the following general formula (b3). [ka]

[0051] In the general formula (b3), R 21 represents a substituted or unsubstituted hydrocarbon group (Y). When the hydrocarbon group (Y) has a substituent, examples of the substituent include a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a hydroxyl group, an amino group, a nitro group, a carboxyl group, and a halogen atom. The halogen atom is, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and is preferably a chlorine atom. When the hydrocarbon group (Y) has a substituent, the number of the substituents may be one or more. When the hydrocarbon group (Y) has a plurality of substituents, the plurality of substituents may be the same or different. When the hydrocarbon group (Y) has a substituent, a preferred substituent is a hydroxyl group.

[0052] In the general formula (b3), the hydrocarbon group (Y) represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. The number of carbon atoms in the hydrocarbon group (Y) does not include the number of carbon atoms in the substituents that the hydrocarbon group (Y) may have. If the number of carbon atoms in the group that can be selected as the hydrocarbon group (Y) exceeds 20, the luster of the metal material after heat treatment such as quenching may be deteriorated, and the storage stability may also be deteriorated.

[0053] Examples of alkyl groups having 1 to 20 carbon atoms that can be selected as the hydrocarbon group (Y) include the same alkyl groups as those described above in the description of the hydrocarbon group (X), and the preferred ranges are also the same as those of the alkyl groups described above.

[0054] Examples of alkenyl groups having 2 to 20 carbon atoms that can be selected as the hydrocarbon group (Y) include the same alkenyl groups as those described above in the description of the hydrocarbon group (X), and the preferred ranges are also the same as those for the alkenyl groups described above.

[0055] Examples of the cycloalkyl group having 3 to 20 carbon atoms that can be selected as the hydrocarbon group (Y) include the same alkenyl groups as the cycloalkyl group described above in the description of the hydrocarbon group (X), and the preferred range is also the same as the cycloalkyl group described above.

[0056] Examples of the cycloalkylalkyl group having 4 to 20 carbon atoms that can be selected as the hydrocarbon group (Y) include the same cycloalkylalkyl groups as those described above in the description of the hydrocarbon group (X), and the preferred range is also the same as that of the cycloalkylalkyl group described above. The cycloalkylalkyl group is a group represented by the following general formula (d1), in which one hydrogen atom of an alkyl group is substituted with a cycloalkyl group. [ka] In the above general formula (d1), the circle represents a cycloalkyl group, and R 41 is an alkylene group. The wavy line indicates the bonding position to the 2-, 4-, or 5-position of the thiazole in the general formula (b3).

[0057] Examples of the cycloalkenyl alkyl group having 4 to 20 carbon atoms that can be selected as the hydrocarbon group (Y) include the same cycloalkenyl alkyl groups as those described above in the description of the hydrocarbon group (X), and the preferred range is also the same as that of the cycloalkenyl alkyl group described above. The cycloalkenylalkyl group is a group represented by the following general formula (d2), in which one of the hydrogen atoms of an alkyl group has been substituted with a cycloalkenyl group. [ka] In the above general formula (d3), the circle represents a cycloalkenyl group, and R 42 is an alkylene group. The wavy line indicates the bonding position to the 2-, 4-, or 5-position of the thiazole in the general formula (b3).

[0058] The aryl group having 6 to 20 carbon atoms that can be selected as the hydrocarbon group (Y) includes the same aryl groups as those described above in the description of the hydrocarbon group (X), and the preferred range is also the same as that of the aryl group described above.

[0059] The arylalkyl group having 7 to 20 carbon atoms that can be selected as the hydrocarbon group (Y) includes the same arylalkyl groups as those described above in the description of the hydrocarbon group (X), and the preferred range is also the same as that of the arylalkyl group described above. The arylalkyl group is a group represented by the following general formula (d3), in which one of the hydrogen atoms of an alkyl group is substituted with an aryl group. [ka] In the above general formula (d3), the double circle represents an aryl group, and R 43 is an alkylene group. The wavy line indicates the bonding position to the 2-, 4-, or 5-position of the thiazole in the general formula (b3).

[0060] In the above general formula (b3), n represents an integer of 0 to 3. n is preferably 1 to 3. If n is 2 or more, there are multiple R 21 may be the same or different.

[0061] where n is 2 or more and two R 21 are adjacent to each other, the two R 21 may or may not form a ring structure. When a ring structure is formed, the two R 21are each independently a group selected from an alkyl group and an alkenyl group, and the alkyl group and the alkyl group, the alkyl group and the alkenyl group, or the alkenyl group and the alkenyl group may be bonded to form a cycloalkyl group, a cycloalkenyl group, or an aryl group.

[0062] More specifically, in the general formula (b3), the two R 21 When forms a ring structure, the thiazole (B3) may be a compound represented by the following general formula (b3-1). [ka] In the above general formula (b3-1), the approximate circle adjacent to the thiazole ring is a cycloalkyl ring having 3 to 20 carbon atoms, a cycloalkenyl ring having 3 to 20 carbon atoms, or an aryl ring having 6 to 20 carbon atoms. The cycloalkyl ring, the cycloalkenyl ring, and the aryl ring may or may not have one or more of the substituents described above as the substituents of the hydrocarbon group (Y) (they may be unsubstituted). In the above general formula (b3-1), R 25 represents R in the above general formula (b3). 21 and is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 16 carbon atoms, even more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 3 carbon atoms.

[0063] Here, in the general formula (d3), the two R 21 When the ring structure is formed, the thiazole (B3) preferably has a molecular skeleton represented by the following structural formula (b3α) (benzothiazole skeleton) or a molecular skeleton represented by the following structural formula (b3β) (naphthothiazole skeleton), and from the viewpoint of availability, it is preferable to have a molecular skeleton represented by the following structural formula (b3α) (benzothiazole skeleton). [ka]

[0064] Furthermore, when the thiazole (B3) has a molecular skeleton represented by the above structural formula (b3α) or the above structural formula (b3β), the thiazole (B3) is preferably a compound represented by the following general formula (b3α-1) or the following structural formula (b3β-1), and more preferably a compound represented by the following general formula (b3α-1). [ka] In the above general formulas (b3α-1) and (b3β-1), R 26 and R 27 represents R in the above general formula (b3). 21 and is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 16 carbon atoms, even more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 3 carbon atoms. p is an integer of 0 to 4, preferably 0 to 3, more preferably 0 to 2, even more preferably 0 to 1, and still more preferably 0. q is an integer of 0 to 6, preferably 0 to 3, more preferably 0 to 2, even more preferably 0 to 1, and still more preferably 0. In the above general formula (b3α-1), R 22 is a substituent that can substitute a benzene ring constituting a benzothiazole ring. Specific examples of the substituent include the substituents described above as the substituents for the hydrocarbon group (Y). In the above general formula (b3β-1), R 23 is a substituent that can substitute the naphthalene ring that constitutes the naphthothiazole ring. Specific examples of the substituent include the substituents described above as the substituents for the hydrocarbon group (Y).

[0065] In addition, in the general formula (b3), the two R 21 does not form a ring structure, or R is present at only one of the 4- and 5-positions of the thiazole skeleton. 21 is bonded to both the 4- and 5-positions of the thiazole skeleton. 21When no bond is bonded, the thiazole (B3) is preferably a compound represented by the following general formula (b3γ-1). [ka] The above general formula (b3γ-1), R 28 represents R in the above general formula (b3). 21 and is preferably an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. 28 may have the substituents described above as the substituents of the hydrocarbon group (Y), or may not have such a substituent, but it is preferable that it does not have such a substituent. The alkyl group more preferably has 1 to 16 carbon atoms, even more preferably has 1 to 10 carbon atoms, and even more preferably has 1 to 3 carbon atoms. The aryl group more preferably has 6 to 10 carbon atoms, and even more preferably 6 carbon atoms. n1 is an integer of 0 to 3, preferably 1 to 3, and more preferably 2 to 3. If n1 is 2 or more, there are multiple R 28 may be the same or different. n1 is 2 or more, and two R 28 are adjacent to each other, the two R 28 does not form a ring structure. In the general formula (b3γ-1), R 28 Preferably, the alkyl group is bonded to one or both of the 4- and 5-positions of the thiazole skeleton as R 28 As the alkyl group, it is preferable that the alkyl group or the aryl group is bonded to the alkyl group.

[0066] Specific examples of the thiazoles (B3) include 2-methylbenzothiazole, 2-methyl-4,5-diphenylthiazole, 2-methylnaphtho[1,2-d]thiazole, 2-(2-hydroxyphenyl)benzothiazole, 2-ethyl-4-methylthiazole, 2-phenylbenzothiazole, benzothiazole, naphtho[1,2-d]thiazole, and thiazole.

[0067] The thiazoles (B3) may be used singly or in combination of two or more kinds.

[0068] (Sulfur compound (B) content) In the heat-treated oil composition of this embodiment, the content of the sulfur compound (B) is preferably 0.01% by mass or more, more preferably 0.02% by mass, and even more preferably 0.05% by mass or more, based on the total amount of the heat-treated oil composition, from the viewpoint of more easily achieving the effects of the present invention. Also, from the viewpoint of more easily suppressing the generation of sludge and shortening of the life of the heat-treated oil composition due to excessive addition of the sulfur compound, the content is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.5% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 0.01 to 2.0% by mass, more preferably 0.02 to 1.0% by mass, and even more preferably 0.05 to 0.5% by mass.

[0069] (Molecular weight of sulfur compound (B)) In the heat-treated oil composition of this embodiment, from the viewpoint of making it easier to exhibit the effects of the present invention, the molecular weight of the sulfur compound (B) is preferably 100 or more, more preferably 110 or more, and even more preferably 120 or more. Also, it is preferably 1,500 or less, more preferably 1,200 or less, and even more preferably 1,000 or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 100 to 1,500, more preferably 110 to 1,200, and even more preferably 120 to 1,000.

[0070] <Additives> The heat treatment oil composition of this embodiment is prepared by mixing the base oil (A) and the sulfur compound (B), and may further contain additives commonly used in heat treatment oil compositions, such as vapor film breakers, brightness improvers, coolant improvers, and antioxidants. The additives may be used alone or in combination of two or more.

[0071] (Vapor film breaker) Examples of vapor film breakers include ethylene-α-olefin copolymers such as ethylene-propylene copolymers (α-olefins having 3 to 20 carbon atoms); hydrogenated products of the ethylene-α-olefin copolymers; α-olefin polymers having 5 to 20 carbon atoms such as 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene; hydrogenated products of the α-olefin polymers; olefin polymers having 3 or 4 carbon atoms such as polypropylene, polybutene, and polyisobutylene; hydrogenated products of the olefin polymers; polymeric compounds such as polymethacrylate, polymethacrylate, polystyrene, and petroleum resin; and asphalt. These vapor film breakers may be used alone or in combination of two or more. The number average molecular weight (Mn) of the vapor membrane breaker is preferably 800 to 100,000. The number average molecular weight (Mn) of the vapor membrane breaker is a polystyrene-equivalent value measured using gel permeation chromatography (GPC). The content of the vapor film breaker is preferably 0.5 to 18 mass %, more preferably 1.0 to 16 mass %, and even more preferably 2.0 to 15 mass %, based on the total amount of the heat-treated oil composition.

[0072] (gloss improver) Examples of glitter improvers include fats and oils; fats and oil fatty acids; alkylsuccinic acids, alkylsuccinimides, alkylsuccinic anhydrides, and derivatives thereof; alkenylsuccinic acids, alkenylsuccinimides, alkenylsuccinic anhydrides, and derivatives thereof; substituted hydroxyaromatic carboxylic acid esters and derivatives thereof; and the like. These glitter improvers may be used alone or in combination of two or more. The content of the glitter improver is preferably 0.1 to 5.0 mass %, more preferably 0.3 to 3.0 mass %, and even more preferably 0.4 to 2.0 mass %, based on the total amount of the heat-treated oil composition.

[0073] (cooling agent) Cooling improvers include, for example, metal-based detergents such as metal sulfonates, metal salicylates, and metal phenates. Examples of metals constituting metal-based detergents include alkali metals such as sodium and potassium, and alkaline earth metals such as magnesium, calcium, and barium. Examples of the cooling improver include imide-based dispersants such as alkenyl succinimides and boron-containing alkenyl succinimides, and mono- or di-carboxylic acid amides typified by fatty acids or succinic acid. These cooling improvers may be used alone or in combination of two or more. The content of the coolability improver is 0.01% by mass to 8.0% by mass based on the total amount of the heat treatment oil composition.

[0074] (antioxidant) Examples of the antioxidant include phenol-based antioxidants and amine-based antioxidants. Examples of phenolic antioxidants include monocyclic phenols such as 2,6-di-tert-butyl-para-cresol, 2,6-di-tert-butyl-4-ethylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-tert-butyl-4-hydroxymethylphenol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-(N,N-dimethylaminomethyl)phenol, 2,6-di-tert-amyl-4-methylphenol, and n-octadecyl-3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate; 4,4'-isopropylidenebis(2,6-di-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-bis(2,6-di-tert-butylphenol), 4,4'-bis(2-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol); and the like. Examples of the amine-based antioxidant include diphenylamine-based antioxidants and naphthylamine-based antioxidants. Examples of diphenylamine antioxidants include alkylated diphenylamines having an alkyl group having 3 to 20 carbon atoms, and specific examples include diphenylamine, monooctyldiphenylamine, monononyldiphenylamine, 4,4'-dibutyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldiphenylamine, tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, and tetranonyldiphenylamine. Examples of naphthylamine antioxidants include alkyl-substituted phenyl-α-naphthylamines having 3 to 20 carbon atoms, and specific examples include α-naphthylamine, phenyl-α-naphthylamine, butylphenyl-α-naphthylamine, hexylphenyl-α-naphthylamine, octylphenyl-α-naphthylamine, and nonylphenyl-α-naphthylamine. These antioxidants may be used alone or in combination of two or more. From the viewpoint of suppressing oxidative degradation and maintaining good brilliance for a long period of time, the antioxidant preferably contains an amine-based antioxidant, more preferably consists of an amine-based antioxidant, and the amine-based antioxidant preferably contains a diphenylamine-based antioxidant, more preferably consists of a diphenylamine-based antioxidant. The content of the antioxidant is preferably 0.01 to 5.0% by mass, more preferably 0.02 to 3.0% by mass, and even more preferably 0.05 to 2.0% by mass, based on the total amount of the heat-treated oil composition.

[0075] (Sulfides (B1), sulfides (B2), and sulfur compounds other than thiazoles (B3)) In the heat-treated oil composition of this embodiment, the sulfur compound (B) may contain other sulfur compounds other than the sulfides (B1), sulfides (B2), and thiazoles (B3), but from the viewpoint of making it easier to achieve the effects of the present invention, it is preferable that the amount of such other sulfur compounds is small. The other sulfur compounds include sulfones and sulfides not having an ester structure. In the heat-treated oil composition of this embodiment, the content of sulfones and sulfides not having an ester structure is each independently preferably less than 0.20 mass%, more preferably less than 0.10 mass%, even more preferably less than 0.01 mass%, even more preferably less than 0.001 mass%, and even more preferably none of these.

[0076] [Physical properties of the heat-treated oil composition of the present invention] <Sulfur content> The heat-treated oil composition of this embodiment has a sulfur content of preferably 10 ppm by mass or more, more preferably 20 ppm by mass or more, and even more preferably 25 ppm by mass or more, based on the total amount of the heat-treated oil composition, and preferably 5,000 ppm by mass or less, more preferably 3,500 ppm by mass or less, and even more preferably 2,500 ppm by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 10 ppm by mass to 5,000 ppm by mass, more preferably 20 ppm by mass to 3,500 ppm by mass, and even more preferably 25 ppm by mass to 2,500 ppm by mass. In this specification, the sulfur content in the heat-treated oil composition means a value measured in accordance with the ultraviolet fluorescence method of JIS K 2541-6:2013 when measured on the order of ppm by mass, and means a value measured in accordance with the wavelength dispersive X-ray fluorescence method of JIS K 2541-7:2013 when measured on the order of % by mass.

[0077] <Amounts of phosphorus, molybdenum, and zinc> The heat-treated oil composition of this embodiment preferably contains less than 0.01 mass% of phosphorus, molybdenum, and zinc, based on the total amount of the heat-treated oil composition, more preferably less than 0.001 mass%, and even more preferably does not contain phosphorus, molybdenum, or zinc. In this specification, the amounts of phosphorus, molybdenum, and zinc in the heat-treated oil composition can be measured in accordance with JPI-5S-38-03.

[0078] <40℃ kinematic viscosity> The heat treatment oil composition of this embodiment has a kinematic viscosity at 40°C set according to the desired oil temperature during heat treatment such as quenching. Heat-treated oil compositions are classified into cold oils used at low oil temperatures, hot oils used at high oil temperatures, and semi-hot oils used at intermediate oil temperatures. Cold oils are classified as Type 1 in JIS K2242:2012, and semi-hot oils and hot oils are classified as Type 2 in JIS K2242:2012. When the heat-treated oil composition of this embodiment is used as cold oil, the kinematic viscosity at 40°C is 5mm 2 / s or more 40mm 2 It is preferable that the ratio is less than / s. When the heat-treated oil composition of this embodiment is used as semi-hot oil or hot oil, the kinematic viscosity at 40°C is 40mm 2 / s or more 500mm 2 / s or less is more preferable. In this specification, the 40°C kinematic viscosity of the heat-treated oil composition means the value measured in accordance with JIS K2283:2000.

[0079] [Method of producing heat-treated oil composition] The method for producing the heat-treated oil composition of this embodiment is not particularly limited. For example, the method for producing the heat-treated oil composition of this embodiment includes a step of mixing one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3) with a sulfur compound (B). The sulfur compound (B) includes at least one compound selected from the group consisting of sulfides (B1) represented by the following general formula (b1), sulfides (B2) represented by the following general formula (b2), and thiazoles (B3) represented by the following general formula (b3): [ka] [In the general formulas (b1) and (b2), R 11 , R 12 , R 13 , and R 14 each independently represents a substituted or unsubstituted hydrocarbon group (X), which represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formulas (b1) and (b2), L 11, L 12 , L 13 , and L 14 each independently represents an alkylene group having 2 to 6 carbon atoms. [ka] [In the general formula (b3), R 21 represents a substituted or unsubstituted hydrocarbon group (Y), which is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 3. If n is 2 or more, there are multiple R 21 may be the same or different. In addition, when n is 2 or more, and two R 21 are adjacent to each other, the two R 21 may form a ring structure.]

[0080] The method for mixing the above components is not particularly limited, and examples thereof include a method having a step of blending a sulfur compound (B) with a base oil (A). When the heat-treated oil composition further contains other components (the above-mentioned additives) other than the base oil (A) and the sulfur compound (B), the other components may be blended into the base oil (A) simultaneously with the sulfur compound (B), or may be blended separately. Note that each component may be blended after being made into a solution (dispersion) by adding a diluent oil or the like. After blending the components, it is preferable to stir them uniformly by a known method. The preferred embodiments of the base oil (A) and the sulfur compound (B) are as described above.

[0081] [Uses of heat treatment oil composition] The heat treatment oil composition of the present embodiment can be used during heat treatment such as quenching of a metal material to improve the luster of the metal material after heat treatment such as quenching. For example, the heat treatment oil composition can be suitably used as a heat treatment oil composition when performing heat treatment such as quenching on various alloy steels such as carbon steel, nickel-manganese steel, chromium-molybdenum steel, and manganese steel. The heat-treated oil composition of this embodiment also has excellent storage stability. Therefore, the heat treatment oil composition of this embodiment is preferably used as a heat treatment oil (preferably, a quenching oil or a tempering oil) for quenching or the like of a metallic material. This embodiment also provides a method for using the heat treatment oil composition, in which the heat treatment oil composition of this embodiment is used as a heat treatment oil (preferably, a quenching oil or a tempering oil) for quenching or the like of a metallic material. When the heat treatment is quenching, the oil temperature of the heat treatment oil composition is preferably set to 40°C to 280°C, more preferably 50°C to 200°C, and even more preferably 60°C to 150°C. When the heat treatment is tempering, the oil temperature may be further increased, for example, up to 300°C. Furthermore, the quenching temperature of the metallic material may be 800°C or higher and 900°C or lower, or may be higher than 900°C and lower than 1100°C. According to the heat treatment oil composition of this embodiment, the brilliance of the metallic material after quenching can be improved even when the quenching temperature of the metallic material is higher than 900°C and lower than 1100°C.

[0082] [One aspect of the present invention provided] According to one aspect of the present invention, the following [1] to

[10] are provided. [1] A lubricating oil composition comprising one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3), and a sulfur compound (B), The heat treatment oil composition, wherein the sulfur compound (B) comprises one or more selected from the group consisting of sulfides (B1) represented by the following general formula (b1), sulfides (B2) represented by the following general formula (b2), and thiazoles (B3) represented by the following general formula (b3): [ka] [In the general formulas (b1) and (b2), R 11 , R 12 , R 13 , and R 14 each independently represents a substituted or unsubstituted hydrocarbon group (X), which represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formulas (b1) and (b2), L 11 , L 12 , L 13 , and L 14 each independently represents an alkylene group having 2 to 6 carbon atoms. [ka] [In the general formula (b3), R 21 represents a substituted or unsubstituted hydrocarbon group (Y), which is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 3. If n is 2 or more, there are multiple R 21 may be the same or different. In addition, when n is 2 or more, and two R 21 are adjacent to each other, the two R 21 may form a ring structure.] [2] In the general formula (b1), R 11 and R 12 The heat treatment oil composition according to the above item [1], wherein at least one of the hydrocarbon groups (X) is an aryl group having 6 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms. [3] The heat treatment oil composition according to (1) or (2) above, wherein the sulfides (B1) include sulfides (B1-1) represented by the following general formula (b1-1): [ka] [In the general formula (b1-1), R 16 and R 17 each independently represents an alkylene group having 1 to 6 carbon atoms. L 11 and L 12 R each independently represents an alkylene group having 2 to 6 carbon atoms. 18 and R 19 each independently represents an alkyl group having 1 to 10 carbon atoms or a hydroxyl group. m1 represents an integer of 0 to 5. m2 represents an integer of 0 to 5. If m1 is 2 or more, there are multiple R 18 may be the same or different. If m2 is 2 or more, there are multiple R 19 may be the same or different.] [4] The heat treatment oil composition according to any one of the above [1] to [3], wherein the thiazole (B3) has a molecular skeleton represented by the following structural formula (b3α) or the following structural formula (b3β): [ka] [5] The heat-treated oil composition according to any one of the above [1] to [4], wherein the sulfur content is 10 ppm by mass to 5,000 ppm by mass based on the total amount of the heat-treated oil composition. [6] The heat treatment oil composition according to any one of the above [1] to [5], wherein the content of the sulfur compound (B) is 0.01 mass% to 2.0 mass% based on the total amount of the heat treatment oil composition. [7] The heat treatment oil composition according to any one of [1] to [6] above, further comprising one or more selected from the group consisting of a vapor film breaker, a glitter improver, a cooling improver, and an antioxidant. [8] The heat treatment oil composition according to any one of the above [1] to [7], which is used as a quenching oil or a tempering oil. [9] A method of using the heat treatment oil composition according to any one of the above [1] to [7] as a quenching oil or a tempering oil.

[10] A method for producing a refrigerant-based oil composition comprising: mixing one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3) with a sulfur compound (B); A method for producing a heat-treated oil composition, wherein the sulfur compound (B) comprises one or more compounds selected from the group consisting of sulfides (B1) represented by the following general formula (b1), sulfides (B2) represented by the following general formula (b2), and thiazoles (B3) represented by the following general formula (b3). [ka] [In the general formulas (b1) and (b2), R 11 , R 12 , R 13 , and R 14 each independently represents a substituted or unsubstituted hydrocarbon group (X), which represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formulas (b1) and (b2), L 11 , L 12 , L 13 , and L 14 each independently represents an alkylene group having 2 to 6 carbon atoms. [ka] [In the general formula (b3), R 21represents a substituted or unsubstituted hydrocarbon group (Y), which is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 3. If n is 2 or more, there are multiple R 21 may be the same or different. In addition, when n is 2 or more, and two R 21 are adjacent to each other, the two R 21 may form a ring structure.] [Example]

[0083] The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0084] [Methods for measuring various physical properties] (1) Kinematic viscosity at 40°C of base oil (A) and heat-treated oil composition The kinematic viscosity at 40°C of the base oil (A) used in each Example and Comparative Example, and of the heat-treated oil composition prepared in each Example and Comparative Example, was measured in accordance with JIS K2283:2000. (2) Sulfur content The sulfur content of the base oil (A) used in each Example and Comparative Example, and the sulfur content of the heat-treated oil composition prepared in each Example and Comparative Example, were measured in accordance with the ultraviolet fluorescence method of JIS K 2541-6:2013 when measured on the order of ppm by mass, and in accordance with the wavelength dispersive X-ray fluorescence method of JIS K 2541-7:2013 when measured on the order of % by mass.

[0085] [Examples 1 to 14, Comparative Examples 1 to 6] The raw materials used in preparing the heat-treated oil compositions of Examples 1 to 14 and Comparative Examples 1 to 6 are shown below.

[0086] (1) Base oil (A) Mineral Oil (A1)-1: High-viscosity mineral oil classified as Group II in the API category (corresponding to bright stock with low sulfur content), sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 396.7 mm 2 / s Mineral oil (A1)-2: Mineral oil classified as Group II in the API category, sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 7.573 mm 2 / s Mineral oil (A1)-3: Mineral oil classified as Group III in the API category, sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 20.57 mm 2 / s Mineral oil (A1)-4: Mineral oil classified as Group II in the API category, sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 31.49 mm 2 / s Mineral oil (A1)-5: Mineral oil classified as Group III in the API category, sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 12.53 mm 2 / s Mineral Oil (A1)-6: High-viscosity mineral oil classified as Group I in the API category (corresponding to bright stock with a high sulfur content), sulfur content: 1.01% by mass, kinematic viscosity at 40°C: 481.8 mm 2 / s

[0087] (2) Sulfur compounds (B) "Sulfides (B1)-1": 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (molecular weight: 642.94) It is a compound represented by the following chemical formula (b1-1-1). [ka] The compound represented by chemical formula (b1-1-1) is a compound represented by general formula (b1-1), wherein R 16 and R 17 is an ethylene group, and L 11 and L 12 is an ethylene group. m1=3, and R 18One of them is a hydroxyl group (substitution position: 4-position), and two are tert-butyl groups (substitution positions: 3-position and 5-position). In addition, m2=3, and R 19 One of them is a hydroxyl group (substitution position: 4-position), and two are tert-butyl groups (substitution positions: 3-position, 5-position).

[0088] "Sulfides (B2)-1": 3,3'-thiodipropionic acid didodecyl (molecular weight: 514.85) It is a compound represented by the following chemical formula (b2-1). [ka] The compound represented by chemical formula (b2-1) is a compound represented by general formula (b2), wherein L 13 and L 14 is an ethylene group, and R 13 and R 14 is an n-dodecyl group.

[0089] "Thiazoles (B3)-1": 2-methylbenzothiazole (molecular weight: 149.21) It is a compound represented by the following chemical formula (b3-1). [ka] The compound represented by chemical formula (b3-1) is a compound represented by general formula (b3) in which n=3 and R 21 One of the substituents is a methyl group (substitution position: 2-position of the thiazole), and the two substituents (substitution positions: 4- and 5-positions of the thiazole) form a benzene ring. That is, the compound represented by chemical formula (b3-1) has a molecular skeleton represented by the above structural formula (b3α), and is also a compound represented by the above general formula (b3α-1).

[0090] "Thiazoles (B3)-2": 2-methyl-4,5-diphenylthiazole (molecular weight: 251.35) It is a compound represented by the following chemical formula (b3-2). [ka] The compound represented by chemical formula (b3-2) is a compound represented by general formula (b3) in which n=3 and R 21 One of them is a methyl group (substitution position: 2-position of thiazole), and two are unsubstituted phenyl groups (substitution positions: 4- and 5-positions of thiazole). The compound represented by chemical formula (b3-2) has two R 21 Since no ring structure is formed by the above, it is also a compound represented by the above general formula (b3γ-1).

[0091] "Thiazoles (B3)-3": 2-methylnaphtho[1,2-d]thiazole (molecular weight: 199.27) It is a compound represented by the following chemical formula (b3-3). [ka] The compound represented by chemical formula (b3-3) is a compound represented by general formula (b3) in which n=3 and R 21 One of the substituents is a methyl group (substitution position: 2-position of the thiazole), and the two substituents (substitution positions: 4- and 5-positions of the thiazole) form a naphthalene ring. In other words, the compound represented by chemical formula (b3-3) has a molecular skeleton represented by the above structural formula (b3β), and is also a compound represented by the above general formula (b3β-1).

[0092] "Thiazoles (B3)-4": 2-(2-hydroxyphenyl)benzothiazole (molecular weight: 227.28) It is a compound represented by the following chemical formula (b3-4). [ka] The compound represented by chemical formula (b3-4) is a compound represented by general formula (b3) in which n=3 and R 21One of the substituents is a hydroxyphenyl group (substitution position: 2-position of the thiazole), and the two substituents (substitution positions: 4- and 5-positions of the thiazole) form a benzene ring. That is, the compound represented by chemical formula (b3-4) has a molecular skeleton represented by the above structural formula (b3α), and is also a compound represented by the above general formula (b3α-1).

[0093] "Thiazoles (B3)-5": 2-ethyl-4-methylthiazole (molecular weight: 127.21) It is a compound represented by the following chemical formula (b3-5). [ka] The compound represented by chemical formula (b3-5) is a compound represented by general formula (b3) in which n=2 and R 21 One of them is an ethyl group (substitution position: 2-position of thiazole), and the other is a methyl group (substitution position: 4-position of thiazole). The compound represented by chemical formula (b3-5) does not have a substituent at the 5-position of thiazole, and the two R 21 Since no ring structure is formed by the above, it is also a compound represented by the above general formula (b3γ-1).

[0094] "Thiazoles (B3)-6": 2-phenylbenzothiazole (molecular weight: 211.28) It is a compound represented by the following chemical formula (b3-6). [ka] The compound represented by chemical formula (b3-6) is a compound represented by general formula (b3) in which n=3 and R 21 One of the substituents is a phenyl group (substitution position: 2-position of the thiazole), and the two substituents (substitution positions: 4- and 5-positions of the thiazole) form a benzene ring. That is, the compound represented by chemical formula (b3-6) has a molecular skeleton represented by the above structural formula (b3α), and is also a compound represented by the above general formula (b3α-1).

[0095] (3) Comparative Example Sulfur Compound "Sulfur compound (B')-1": 4,4'-thiobis(6-tert-butyl-m-cresol) (molecular weight: 358.54) They are sulfides without an ester structure, represented by the following chemical formula (b'-1). [ka]

[0096] "Sulfur compound (B')-2": Diphenyl sulfone (molecular weight: 218.27) It is a sulfone represented by the following chemical formula (b'-2). [ka]

[0097] "Sulfur compound (B')-3": Dibenzothiophene (molecular weight: 184.26) The thiophenes are represented by the following chemical formula (b'-3). [ka]

[0098] (4) Additives Vapor film breaker: polymer ·Brilliance improver: carboxylic acid Amine antioxidants: Diphenylamine antioxidants Phenolic antioxidant: 2,6-di-tert-butyl-paracresol

[0099] The above raw materials were thoroughly mixed in the blending amounts (mass %) shown in Tables 1 to 4 to prepare the heat-treated oil compositions of Examples 1 to 14 and Comparative Examples 1 to 6, respectively.

[0100] [Evaluation method] (1) Evaluation method for brilliance The brilliance of the steel material after quenching was evaluated with reference to "The effect of oxygen in a heat treatment oil bath on brilliance (Idemitsu Tribo Review, No. 31, pp. 1963-1966, published September 30, 2008)". Specifically, a dumbbell-shaped steel material S45C (diameter: 16 mm, length: 30 mm, hardness H RC :16) and cylindrical steel material SUJ2 (diameter: 10 mm, length: 30 mm, hardness H RC :15) were combined to form the test specimen. Specifically, a dumbbell-shaped S45C steel material and a cylindrical SUJ2 steel material were tied together at their centers using SUS303 wire, thereby binding the dumbbell-shaped S45C steel material and the cylindrical SUJ2 steel material together (see Figure 1). The "Steel S45C" is a carbon steel specified in JIS G 4051. The "Steel SUJ2" is a high carbon chromium bearing steel specified in JIS G 4805. The "SUS303 wire" is a stainless steel wire specified in JIS G 4309. The test pieces were then heated in a furnace with a mixed gas atmosphere of nitrogen and hydrogen, and then quenched by placing the test pieces in a heat treatment oil composition, thereby conducting a quenching test. The hardening test was carried out under the following three conditions.

[0101] (Quenching test condition 1: Hot oil simulated test, Table 1) Test subjects: Comparative Examples 1 to 3, Examples 1 to 8 Furnace temperature: 850℃ Test piece retention time in the furnace: 40 minutes after the furnace temperature reaches 850°C Temperature of heat treatment oil composition: 120°C Immersion time of test piece in heat treatment oil composition (quenching time): 10 minutes

[0102] (Quenching test condition 2: Cold oil assumed test 1, Table 2 and Table 3) Test subjects: Comparative Examples 4 to 5, Examples 9 to 12 Furnace temperature: 850℃ Test piece retention time in the furnace: 40 minutes after the furnace temperature reaches 850°C Temperature of heat treatment oil composition: 80°C Immersion time of test piece in heat treatment oil composition (quenching time): 10 minutes

[0103] (Quenching test condition 3: Cold oil simulated test 2, Table 4) Test subjects: Comparative Example 6, Examples 13 to 14 Furnace temperature: 975℃ Test piece retention time in the furnace: 40 minutes after the furnace temperature reaches 975°C Temperature of heat treatment oil composition: 60°C Immersion time of test piece in heat treatment oil composition (quenching time): 10 minutes

[0104] After quenching, the test pieces were evaluated for brilliance based on the following criteria, focusing on "brightness," "coloring of the edge," and "coloring of the contact area." Furthermore, based on the evaluation results of "brightness," "coloring of the edge," and "coloring of the contact area," the brilliance of the test pieces was evaluated comprehensively based on the following criteria. (brightness) Appearance samples with the specified coloring were prepared and visually compared with the color of the test piece after quenching. The degree of coloring of the appearance sample is expressed by the following numerical values. 0: No coloring at all. 1: Lightly colored. 2: Dark brown to black coloration. (Coloring of the edges) The edge of the test piece (see FIG. 1) was visually observed and evaluated according to the following criteria. 0: No or almost no coloring. 1: Light coloring is observed. 2: Dark brown to black coloration is observed. (Coloring of contact parts) The contact area of the test piece (the contact area between the dumbbell-shaped steel material and the cylindrical steel material, see Figure 1) was visually observed and evaluated according to the following criteria. 0: No or almost no coloring. 1: Light coloring is observed. 2: Dark brown to black coloration is observed.

[0105] (Overall evaluation of brilliance) Using the evaluation results of "brightness," "coloring of the edge," and "coloring of the contact portion," a comprehensive evaluation was made based on the following criteria. S rating: The sum of the evaluation results for "brightness," "edge coloring," and "contact coloring" is 0. Evaluation A: The sum of the evaluation results for "brightness," "edge coloring," and "contact coloring" is 1. Evaluation B: The sum of the evaluation results for "brightness," "coloring of the edge," and "coloring of the contact area" is 2. Evaluation C: The sum of the evaluation results for "brightness," "coloring of the edge," and "coloring of the contact area" is 3 or more However, if the evaluation result of any one of "brightness," "coloring of edge," and "coloring of contact portion" was 2 or more, the evaluation was given as C. Heat-treated oil compositions rated S have extremely excellent luster. Heat-treated oil compositions rated A have excellent luster. On the other hand, heat-treated oil compositions rated B have slightly poor luster. Heat-treated oil compositions rated C have poor luster.

[0106] (2) Evaluation method for storage stability Approximately 80% of the heat-treated oil composition was placed in a 1,000 mL colorless, transparent glass container, and allowed to stand at room temperature (25°C) for one month in an environment away from direct sunlight. After leaving it to stand for one month, the heat-treated oil composition in the glass container was visually observed and evaluated based on the following criteria. In this example, "good" was considered to be acceptable. "Good": No sediment. "Mild": Sediment is observed to the extent that it does not cover the entire bottom of the glass container. "Moderate": Sediment covers the entire bottom of the glass container and is thinly visible. "Severe": Sediment is observed to the extent that it forms layers.

[0107] (3) Oxidation degradation test With reference to "6.3 Stability test method" of JIS K2242:2012, the heat-treated oil composition was subjected to oxidative degradation by the following method. 400 mL of heat-treated oil was placed in a 730 mL (φ45 mm × length 500 mm) container and subjected to oxidative degradation for 24 or 48 hours at a temperature of 170°C and an air flow rate of 10 L / h without adding a catalyst. The kinematic viscosity at 40°C was measured for the heat-treated oil composition that had not been oxidatively deteriorated (hereinafter also referred to as "new oil") and the heat-treated oil composition that had been oxidatively deteriorated, and the luster was evaluated based on "(1) Evaluation method for luster." The increase rate of the kinematic viscosity at 40°C after oxidative deterioration (the increase rate of the kinematic viscosity at 40°C from the new oil) was calculated using the following formula. (Increase in kinematic viscosity at 40°C from new oil) = [(kinematic viscosity at 40°C of oil after oxidative degradation) - (kinematic viscosity at 40°C of new oil)] / (kinematic viscosity at 40°C of new oil) The greater the rate of increase in kinematic viscosity at 40°C from new oil, the more easily the heat-treated oil composition will undergo oxidative degradation. In other words, this means that the heat-treated oil composition has low oxidative stability. Conversely, the smaller the rate of increase in kinematic viscosity at 40°C from new oil, the less likely the heat-treated oil composition will undergo oxidative degradation. In other words, this means that the heat-treated oil composition has high oxidative stability. With regard to brilliance, the less deterioration there is compared to before forced aging, the better the heat-treated oil composition can be said to be.

[0108] Table 1 shows the results of evaluation of luster and storage stability for the heat treatment oil compositions of Examples 1 to 8 and Comparative Examples 1 to 3. Fig. 2 shows the state of test pieces after a quenching test using the heat treatment oil compositions of Examples 1 to 8 and Comparative Examples 1 to 3. Table 2 shows the results of measuring the kinematic viscosity at 40°C and evaluating the luster of the heat-treated oil compositions of Comparative Examples 4 and 5 and Examples 9 and 10. Table 2 also lists the results for the heat-treated oil compositions, both for fresh oil and for the oil after a 24-hour oxidation degradation test. Figure 3 shows the condition of test pieces after a quenching test using the heat-treated oil compositions of Comparative Examples 4 and 5 and Examples 9 and 10. Table 3 shows the results of measuring the kinematic viscosity at 40°C and evaluating the luster of the heat-treated oil compositions of Examples 9, 11, and 12. Table 3 also lists the results for the new oil, the oil after a 24-hour oxidation degradation test, and the oil after a 48-hour oxidation degradation test for the heat-treated oil compositions. Figure 4 shows the condition of test pieces after a quenching test using the heat-treated oil compositions of Examples 9, 11, and 12. Table 4 shows the results of evaluating the luster of the heat treatment oil compositions of Comparative Example 6 and Examples 13 to 14. Fig. 5 shows the state of test pieces after the quenching test using the heat treatment oil compositions of Comparative Example 6 and Examples 13 to 14. In Tables 1 and 2, ">" means "less than."

[0109] [Table 1] [Table 2] [Table 3] [Table 4]

[0110] From Table 1, we can see the following: The results shown in Examples 1 to 8 show that heat treatment oil compositions containing sulfides (B1), sulfides (B2), or thiazoles (B3) as the sulfur compound (B) have excellent brightness of test pieces after quenching and also have excellent storage stability. On the other hand, the results shown in Comparative Examples 2 and 3 show that the heat treatment oil compositions containing sulfur compound (B')-1, which is a sulfide without an ester structure, or sulfone compound (B')-2, which is a sulfone, have excellent brightness of the test pieces after quenching, but poor storage stability.

[0111] From Table 2, we can see the following: The results shown in Examples 9 to 10 show that heat-treated oil compositions containing sulfides (B1) or thiazoles (B3) as the sulfur compound (B) have excellent brilliance in the test pieces after quenching, not only in the fresh oil state but also after a 24-hour oxidation degradation test. On the other hand, the results shown in Comparative Example 5 show that the heat-treated oil composition containing the sulfur compound (B')-3, which is a thiophene, has excellent luster in the test pieces after quenching when in the fresh oil state, but the luster in the test pieces after quenching is inferior after a 24-hour oxidation degradation test. Furthermore, the heat-treated oil composition of Comparative Example 5 showed a significantly increased 40°C kinematic viscosity after the 24-hour oxidative degradation test compared to the heat-treated oil compositions of Examples 9 and 10, indicating that oxidative degradation is more likely to progress (low oxidative stability).

[0112] From Table 3, we can see the following: The results shown in Examples 9, 11, and 12 show that by incorporating an antioxidant, as in the heat treatment oil compositions of Examples 11 and 12, the brilliance of the test pieces after quenching was excellent, even after a 48-hour oxidation degradation test. Furthermore, the heat-treated oil composition of Example 9, which does not contain an antioxidant, showed a significantly increased kinematic viscosity at 40°C after the oxidative degradation test compared to the heat-treated oil compositions of Examples 11 and 12, which did contain antioxidants, indicating that oxidative degradation is more likely to progress (low oxidative stability).

[0113] Table 4 reveals the following: The results shown in Examples 13 to 14 show that the heat treatment oil composition containing sulfides (B1) or thiazoles (B3) provides excellent brilliance to the test pieces after quenching, even when the quenching temperature is as extremely high as 975°C.

Claims

1. The oil composition contains one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3), and a sulfur compound (B), The heat treatment oil composition, wherein the sulfur compound (B) comprises at least one selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and thiazoles (B3) represented by the following general formula (b3): 【Chemical 1】 [In the general formula (b1), R １１ and R １２ each independently represents a substituted or unsubstituted hydrocarbon group (X), which represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formula (b1), L １１ and L １２ each independently represents an alkylene group having 2 to 6 carbon atoms. 【Chemistry 2】 [In the general formula (b3), R ２１ represents a substituted or unsubstituted hydrocarbon group (Y), which is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 3. When n is 2 or more, there are multiple R ２１ may be the same or different. In addition, when n is 2 or more, two R ２１ are adjacent to each other, the two R ２１ may form a ring structure.]

2. In the general formula (b1), R １１ and R １２ 2. The heat treatment oil composition according to claim 1, wherein at least one of the hydrocarbon groups (X) is an aryl group having 6 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms.

3. The heat treatment oil composition according to claim 1 or 2, wherein the sulfides (B1) include sulfides (B1-1) represented by the following general formula (b1-1): 【Chemistry 3】 [In the general formula (b1-1), R １６ and R １７ each independently represents an alkylene group having 1 to 6 carbon atoms. L １１ and L １２ R each independently represents an alkylene group having 2 to 6 carbon atoms. １８ and R １９ each independently represents an alkyl group having 1 to 10 carbon atoms or a hydroxyl group. m1 represents an integer of 0 to 5; m2 represents an integer of 0 to 5. When m1 is 2 or more, there are multiple R １８ may be the same or different. When m2 is 2 or more, there are multiple R １９ may be the same or different.]

4. The heat treatment oil composition according to any one of claims 1 to 3, wherein the thiazole (B3) has a molecular skeleton represented by the following structural formula (b3α) or the following structural formula (b3β): 【Chemistry 4】

5. The heat treatment oil composition according to any one of claims 1 to 4, wherein the content of the sulfur compound (B) is 0.01 mass% to 2.0 mass% based on the total amount of the heat treatment oil composition.

6. A composition comprising one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3), and a sulfur compound (B), The heat treatment oil composition, wherein the sulfur compound (B) comprises one or more selected from the group consisting of sulfides (B2) represented by the following general formula (b2): The content of the sulfur compound (B) is 0.01 mass% to 2.0 mass% based on the total amount of the heat treatment oil composition. 【Chemistry 5】 In the general formula (b2), R 13 and R 14 each independently represent a substituted or unsubstituted hydrocarbon group (X). The hydrocarbon group (X) represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formula (b2), L 13 and L 14 each independently represent an alkylene group having 2 to 6 carbon atoms.]

7. The heat treatment oil composition according to any one of claims 1 to 6, wherein the sulfur content is 10 ppm by mass to 5,000 ppm by mass based on the total amount of the heat treatment oil composition.

8. The heat treatment oil composition according to any one of claims 1 to 7, further comprising one or more selected from the group consisting of a steam film breaker, a glitter improver, a cooling improver, and an antioxidant.

9. The heat treatment oil composition according to any one of claims 1 to 8, which is used as a quenching oil or a tempering oil.

10. A method for using the heat treatment oil composition according to any one of claims 1 to 8 as a quenching oil or a tempering oil.

11. The method includes a step of mixing one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3) with a sulfur compound (B), A method for producing a heat-treated oil composition, wherein the sulfur compound (B) comprises one or more compounds selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and thiazoles (B3) represented by the following general formula (b3): 【Chemistry 6】 [In the general formula (b1), R １１ and R １２ each independently represents a substituted or unsubstituted hydrocarbon group (X), which represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formulas (b1) and (b2), L １１ and L １２ each independently represents an alkylene group having 2 to 6 carbon atoms. 【Chemistry 7】 [In the general formula (b3), R ２１ represents a substituted or unsubstituted hydrocarbon group (Y), which is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. n represents an integer of 0 to 3. When n is 2 or more, there are multiple R ２１ may be the same or different. In addition, when n is 2 or more, two R ２１ are adjacent to each other, the two R ２１ may form a ring structure.]

12. A method for producing a grease-resistant oil, comprising the step of mixing one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3) with a sulfur compound (B), A method for producing a heat-treated oil composition, wherein the sulfur compound (B) comprises one or more selected from the group consisting of sulfides (B2) represented by the following general formula (b2): In the step, the content of the sulfur compound (B) is mixed so as to be 0.01 mass% to 2.0 mass% based on the total amount of the heat-treated oil composition. 【Chemistry 8】 In the general formula (b2), R 13 and R 14 each independently represent a substituted or unsubstituted hydrocarbon group (X). The hydrocarbon group (X) represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, a cycloalkylalkyl group having 4 to 20 carbon atoms, a cycloalkenylalkyl group having 4 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms. In addition, in the general formula (b2), L 13 and L 14 each independently represent an alkylene group having 2 to 6 carbon atoms.]

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