Heat treatment oil composition

Abstract

The present invention addresses the problem of providing a heat treatment oil composition which contains a sulfur compound and is capable of improving the brilliance of a metal material after heat treatment such as quenching, without excessively increasing the sulfur content. Therefore, the problem is solved by a heat treatment oil composition containing: one or more base oils (A) selected from the group consisting of a mineral oil (A1), a synthetic oil (A2), and a vegetable oil (A3); and one or more sulfur-containing aromatic compounds (B) selected from the group consisting of specific sulfides (B1) and specific sulfones (B2).

Description

[Technical field]

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

[0002] Metallic materials such as steel may be subjected to heat treatments such as quenching, tempering, annealing, and normalizing in order 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 specified 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 the performance as a coolant, the heat treatment oil composition is also required to maintain the surface gloss of the metal material before quenching after quenching in order to increase the commercial value of the metal material after quenching. That is, the heat treatment oil composition is required to have the performance of improving the luster of the metal material after quenching.

[0004] For example, Patent Document 1 proposes a heat treatment oil composition containing at least one of mineral oils and synthetic oils having a sulfur content of 300 mass ppm or less, a base oil containing at least one of sulfur and sulfur compounds to adjust the total sulfur content to 3 mass ppm to 1000 mass ppm, and at least one selected from the group consisting of alkaline earth metal salts of sulfonic acids, alkaline earth metal salts of phenols, alkenylsuccinic acid derivatives, fatty acids, fatty acid derivatives, phenol-based antioxidants, and amine-based antioxidants. Patent Document 1 also proposes that the heat treatment oil composition can be used to improve the luster of metal materials after quenching. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-070632 Summary of the Invention [Problem to be solved by the invention]

[0006] It is generally believed that if a heat treatment oil composition with a low sulfur content is used for quenching, the luster of the metal material after quenching is reduced. Therefore, it is considered to improve the luster of the metal material after quenching by using a heat treatment oil composition in which a sulfur compound is blended to increase the sulfur content. On the other hand, if the sulfur content in the heat treatment oil composition is excessively increased, sludge may be generated and the life of the heat treatment oil composition itself may be shortened. Therefore, it is desired to provide a heat treatment oil composition containing a sulfur compound that can improve the luster of a metal material after quenching without excessively increasing the sulfur content in the heat treatment oil composition. However, such a study has not yet been fully conducted. In addition, such a demand exists not only for quenching but also for heat treatment oil compositions used for other heat treatments such as tempering.

[0007] Therefore, an object of the present invention is to provide a heat treatment oil composition containing a sulfur compound that can improve the luster of metal materials after heat treatment such as quenching without excessively increasing the sulfur content. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors discovered that a heat-treated oil composition in which at least one of specific sulfides and specific sulfones is blended into a base oil as a sulfur compound can solve the above-mentioned problems, and thus completed the present invention.

[0009] That is, the present invention relates to the following [1] to [2]. [1] One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); one or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and sulfones (B2) represented by the following general formula (b2); A heat treatment oil composition comprising: [ka] [In the general formula (b1), R 11 , R 12 , and R 13 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms; and p is 0 or 1.] [ka] [In the general formula (b2), R 21 and R 22 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.] [2] One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); one or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and sulfones (B2) represented by the following general formula (b2); A method for producing a heat treatment oil composition, comprising the step of mixing the above. [ka] [In the above general formula (b1), R 11 , R 12 , and R 13 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms; and p is 0 or 1.] [ka] [In the general formula (b2), R 21 and R 22 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.] Effect of the Invention

[0010] According to the present invention, it is possible to provide a heat treatment oil composition containing a sulfur compound that can improve the luster of metal materials after heat treatment such as quenching without excessively increasing the sulfur content. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram showing the positions of the "ends" and "contact parts" visually observed for the test pieces used in the examples. [Diagram 2] 2 is a drawing-substitute photograph showing the state of a test piece after a quenching test using the heat treatment oil compositions of Examples 1 to 10. [Diagram 3] 2 is a photograph substituting a drawing showing the state of a test piece after a quenching test using the heat treatment oil compositions of Comparative Examples 1 to 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In this specification, the lower limit and upper limit described in stages for the preferred numerical range (e.g., range of content, etc.) 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." In addition, unless otherwise specified, a numerical range of "lower limit value to upper limit value" described in this specification means not less than the lower limit value and not more than the upper limit value. In this specification, the numerical values ​​in the examples are numerical values ​​that can be used as upper or lower limits. In this specification, "kinematic viscosity at 40°C" is also referred to as "40°C kinematic viscosity."

[0013] [Embodiments of the heat treatment oil composition of the present invention] The heat treatment oil composition of the present invention is a heat treatment oil composition containing one or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3), and one or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and sulfones (B2) represented by the following general formula (b2).

[0014] [ka] [In the above general formula (b1), R 11 , R 12 , and R 13 is a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. p is 0 or 1.]

[0015] [ka] [In the general formula (b2), R 21 and R 22 is a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.]

[0016] The present inventors have conducted extensive research into sulfur compounds to be incorporated into heat treatment oil compositions in order to improve the luster of metal materials after heat treatment such as quenching. As a result, they have found that sulfides in which an aryl group such as a phenyl group is bonded to a sulfur atom and sulfones in which an aryl group such as a phenyl group is bonded to a sulfur atom are extremely effective as sulfur compounds for improving the luster of metal materials after heat treatment such as quenching. Based on these findings, the present inventors have further conducted various research and have completed the present invention.

[0017] In the following description, the "base oil (A)" and the "sulfur-containing aromatic compound (B)" will also be referred to as the "component (A)" and the "component (B)", respectively. In addition, "mineral oil (A1)", "synthetic oil (A2)", and "vegetable oil (A3)" are also referred to as "component (A1)", "component (A2)", and "component (A3)", respectively. Furthermore, the sulfides (B1) represented by the above general formula (b1) and the sulfones (B2) represented by the above general formula (b2) are also referred to as "component (B1)" and "component (B2)", respectively.

[0018] The heat-treated oil composition of one embodiment of the present invention may be composed only of component (A) and component (B), but may also contain other components other than component (A) and component (B) as long as the effects of the present invention are not impaired. In one embodiment of the heat-treated oil composition of the present invention, the total content of components (A) and (B) is preferably 75% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, and even more preferably 85% by mass to 100% by mass, based on the total amount of the heat-treated oil composition.

[0019] Each component contained in the heat treatment oil composition of the present invention will be described in detail below.

[0020] <Base oil (A)> The heat treatment oil composition of the present invention contains a base oil (A). The base oil (A) is one or more oils 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.

[0021] (Mineral oil (A1)) As the mineral oil (A1), any mineral oil commonly used in heat treatment oil compositions can be used without particular limitation. Specific examples of the mineral oil (A1) include atmospheric residual oil obtained by atmospheric distillation of crude oil such as paraffinic crude oil, intermediate base crude oil, naphthenic crude oil, etc.; distillate oil obtained by vacuum distillation of such atmospheric residual oil; mineral oil obtained by subjecting such distillate oil to one or more treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, etc.; wax isomerized mineral oil, etc.

[0022] The mineral oil (A1) may also be a highly refined mineral oil (A1-1) 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 (A1-1) 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 (A1-1).

[0023] The mineral oil (A1) may also be bright stock (A1-2). In this specification, "bright stock" refers to a high-viscosity mineral oil obtained by vacuum distillation of atmospheric residual oil obtained by atmospheric distillation of crude oil such as paraffinic crude oil, intermediate base 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. The sulfur content of the bright stock (A1-2) is, for example, 0.30% by mass to 2.0% by mass based on the total amount of the bright stock (A1-2). It is preferable that Bright Stock (A1-2) is classified as Group I in the API category.

[0024] In some heat treatment oil compositions, mineral oil containing bright stock with a high sulfur content is blended in order to increase the sulfur content and improve the luster of metal materials after heat treatment such as quenching. However, as a result of the inventor's investigation, it was found that in heat treatment oil compositions blended with mineral oil containing bright stock with a high sulfur content, the luster of metal materials after heat treatment such as quenching may decrease, and that the luster of metal materials after heat treatment such as quenching is likely to decrease especially when the heat treatment temperature is high, such as 900°C or higher (particularly 950°C or higher). According to the inventors' investigations, it has been confirmed that even when a mineral oil (A1) containing bright stock (A1-2) 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 adding a sulfur-containing aromatic compound (B).

[0025] In the heat treatment oil composition of one embodiment of the present invention, the bright stock (A1-2) is preferably blended with the base oil (A) depending on the desired viscosity and desired sulfur content required for the heat treatment oil composition. When the base oil (A) contains bright stock (A1-2), the content of bright stock (A1-2) is preferably 1 mass % or more, more preferably 2 mass % or more, and even more preferably 3 mass % or more based on the total amount of the base oil (A), and is preferably 20 mass % or less, more preferably 15 mass % or less, and even more preferably 10 mass % or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the content is preferably 1 mass % to 20 mass %, more preferably 2 mass % to 15 mass %, and even more preferably 3 mass % to 10 mass %.

[0026] (Synthetic oil (A2)) As the synthetic oil (A2), any synthetic oil generally used in heat treatment oil compositions can be used without 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 kinds.

[0027] (Vegetable oil (A3)) As the vegetable oil (A3), any vegetable oil commonly used in heat treatment oil compositions can be used without 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 kinds.

[0028] (Preferred embodiment of base oil (A)) In one embodiment of the heat treatment oil composition of the present invention, the base oil (A) may be one or more oils selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3), but is preferably one or more oils selected from the group consisting of mineral oils (A1) and synthetic oils (A2). It is more preferable that the base oil (A) consists solely of a mineral oil (A1) or consists solely of a synthetic oil (A2).

[0029] (Kinematic viscosity of base oil (A) at 40°C) The base oil (A) used in one embodiment of the present invention preferably has a kinematic viscosity at 40°C of 5mm 2 / s~600mm 2 / s, more preferably 6mm 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 kinetic viscosity of base oil (A) at 40°C is 5mm 2 If the 40°C kinematic viscosity of the base oil (A) is 600 mm / s or more, it is easy to maintain the flash point high and to obtain a heat treatment oil composition that suppresses the generation of oil smoke. 2 / s or less, it is easy to obtain a heat treatment oil composition having good cooling performance. In this specification, the 40° C. kinematic viscosity is a value measured in accordance with JIS K2283:2000. In addition, in the heat-treated oil composition of one embodiment of the present invention, it is preferable to use a mixture of multiple base oils having different 40°C kinetic viscosities, taking into consideration the ease of adjusting the 40°C kinetic viscosity of the base oil (A).

[0030] (Base oil (A) content) In the heat treatment oil composition of one embodiment of the present invention, 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 treatment oil composition. Also, it is preferably 99.98 mass% or less.

[0031] <Sulfur-containing aromatic compound (B)> The heat treatment oil composition of the present invention contains a sulfur-containing aromatic compound (B). If the heat treatment oil composition does not contain the sulfur-containing aromatic compound (B), the luster of the metal material after heat treatment such as quenching cannot be improved. The sulfur-containing aromatic compound (B) is at least one selected from the group consisting of sulfides (B1) and sulfones (B2). The sulfides (B1) and sulfones (B2) will be described in detail below. In the description of the sulfur-containing aromatic compound (B), the "number of carbon atoms a to b" in the expression "substituted or unsubstituted X group having carbon atoms a to b" represents the number of carbon atoms when the X group is unsubstituted, and does not include the number of carbon atoms of the substituent when the X group is substituted.

[0032] (Sulfides (B1)) The sulfide (B1) is a sulfide represented by the following general formula (b1). [ka] In the general formula (b1), R 11 , R 12 , and R 13 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. p is 0 or 1. When the aryl group having 6 to 10 carbon atoms has a substituent, the substituent is an 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 sulfhydryl group, or a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, preferably a chlorine atom). The sulfides (B1) may be used alone or in combination of two or more.

[0033] R 11 , R 12 , and R 13 Examples of the substituted or unsubstituted aryl group having 6 to 10 carbon atoms selected as the aryl group include a substituted or unsubstituted phenyl group and naphthyl group, and among these, a substituted or unsubstituted phenyl group is preferred. As the substituted or unsubstituted phenyl group, a phenyl group represented by the following general formula (bx) is preferable.

[0034] [ka] In the above general formula (bx), R x1 is an 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 sulfhydryl group, and a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, preferably a chlorine atom). In addition, the wavy line in the general formula (bx) indicates the bond position with the sulfur atom (R 11 and R 12 (In the case of R 13 (in the case of R x1Examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms selected as include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl groups; and alkenyl groups such as ethenyl, propenyl, butenyl, pentenyl, and hexenyl groups. The alkyl and alkenyl groups may be linear or branched. That is, when the aliphatic hydrocarbon group having 1 to 10 carbon atoms as the substituent is a butyl group, the butyl group may be any of an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Also, R x1 Examples of the hydrocarbon group constituting the alkoxy group having 1 to 10 carbon atoms selected as the substituent include the same as the aliphatic hydrocarbon group having 1 to 10 carbon atoms as the substituent. In the above general formula (bx), m is an integer of 0 to 5. m is preferably 0 to 4, more preferably 0 to 3. When m is 2 or more, a plurality of R x1 may be the same or different from each other.

[0035] Here, in the above general formula (bx), m=0 is preferable. In addition, in the above general formula (bx), when m is 1, R x1 is preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms or a hydroxyl group. x1 The aliphatic hydrocarbon group having 1 to 10 carbon atoms selected as is preferably an aliphatic hydrocarbon group having 1 to 4 carbon atoms, more preferably a methyl group or a tert-butyl group. In addition, in the above general formula (bx), when m is 2 or more, a plurality of R x1 is preferably selected from an aliphatic hydrocarbon group having 1 to 10 carbon atoms and a hydroxyl group. x1 may be the same or different, but is preferably a combination of an aliphatic hydrocarbon group having 1 to 10 carbon atoms and a hydroxyl group. x1The aliphatic hydrocarbon group having 1 to 10 carbon atoms selected as R is preferably an aliphatic hydrocarbon group having 1 to 4 carbon atoms, more preferably a methyl group or a tert-butyl group. x1 are a methyl group, a tert-butyl group, and a hydroxyl group. Preferable examples of the substituted or unsubstituted phenyl group represented by the above general formula (bx) include a phenyl group, a tert-butylphenyl group, and a 6-tert-butyl-m-cresyl group.

[0036] In the above general formula (b1), p is 0 or 1, but from the viewpoint of making it easier to exert the effects of the present invention, p is preferably 0.

[0037] Specific examples of the sulfides (B1) include diphenyl sulfide, phenylbis(phenylthio)methane, 4-tert-butyldiphenyl sulfide, 4,4'-thiobis(6-tert-butyl-m-cresol), etc. Among these, diphenyl sulfide, 4-tert-butyldiphenyl sulfide, and 4,4'-thiobis(6-tert-butyl-m-cresol) are preferred, and diphenyl sulfide and 4,4'-thiobis(6-tert-butyl-m-cresol) are more preferred.

[0038] (Sulfones (B2)) The sulfone (B2) is a sulfone represented by the following general formula (b2). [ka] In the general formula (b2), R 21 and R 22 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. When the aryl group having 6 to 10 carbon atoms has a substituent, the substituent is an 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 sulfhydryl group, or a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, preferably a chlorine atom). The sulfones (B2) may be used alone or in combination of two or more kinds.

[0039] R 21 and R 22 Examples of the substituted or unsubstituted aryl group having 6 to 10 carbon atoms selected as the aryl group include a substituted or unsubstituted phenyl group and naphthyl group, and among these, a substituted or unsubstituted phenyl group is preferred. The substituted or unsubstituted phenyl group includes the phenyl group represented by the above general formula (bx), and preferred embodiments are also as described above.

[0040] A specific example of the sulfones (B2) is preferably diphenyl sulfone.

[0041] (Content of sulfur-containing aromatic compound (B)) In the heat treatment oil composition of one embodiment of the present invention, the content of the sulfur-containing aromatic compound (B) is preferably 0.02 mass% or more, more preferably 0.05 mass% or more, even more preferably 0.08 mass% or more, and even more preferably 0.10 mass% or more based on the total amount of the heat treatment oil composition, from the viewpoint of making the effects of the present invention more easily exhibited and from the viewpoint of making it easier to suppress the generation of sludge and the shortening of the life of the heat treatment oil composition due to the excessive addition of sulfur compounds. Also, it is preferably 5.5 mass% or less, more preferably 5.0 mass% or less, even more preferably 4.5 mass% or less, and even more preferably 4.0 mass% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably 0.02 mass% to 5.5 mass%, more preferably 0.05 mass% to 5.0 mass%, even more preferably 0.08 mass% to 4.5 mass%, and still more preferably 0.10 mass% to 4.0 mass%.

[0042] (Molecular weight of sulfur-containing aromatic compound (B)) In the heat treatment oil composition of one embodiment of the present invention, from the viewpoint of more easily achieving the effects of the present invention, the molecular weight of the sulfur-containing aromatic compound (B) is preferably 100 to 500, more preferably 120 to 450, and even more preferably 135 to 400.

[0043] <Additives> The heat treatment oil composition of one embodiment of the present invention is basically prepared by blending component (A) and component (B), but may further include additives commonly used in heat treatment oil compositions if desired. Examples of such additives include at least one selected from a steam film breaker, a glitter improver, an antioxidant, and a detergent dispersant. In addition, such additives preferably include at least one selected from a steam film breaker, a glitter improver, and an antioxidant. Furthermore, such additives more preferably include at least one selected from a steam film breaker and a glitter improver. Since component (B) has an antioxidant performance, the antioxidant performance of the heat treatment oil composition can be ensured even without the inclusion of an antioxidant. That is, the heat treatment oil composition of one embodiment of the present invention may be a heat treatment oil composition that contains, in addition to component (A) and component (B), one or more additives selected from a steam film breaker, a glitter improver, an antioxidant, and a detergent dispersant, or it may be a heat treatment oil composition consisting of component (A) and component (B) and one or more additives selected from a steam film breaker, a glitter improver, an antioxidant, and a detergent dispersant. In addition, a heat treatment oil composition according to one embodiment of the present invention may be a heat treatment oil composition comprising component (A) and component (B) as well as one or more additives selected from a steam film breaker, a glitter improver, and an antioxidant. Furthermore, the heat treatment oil composition of one embodiment of the present invention may be a heat treatment oil composition comprising component (A) and component (B) and one or more additives selected from a steam film breaker and a glitter improver. Since component (B) has an oxidation inhibitory effect, the oxidation inhibitory effect of the heat treatment oil composition can be ensured even without the inclusion of an antioxidant.

[0044] (Vapor film breaker) Examples of the vapor film breaker 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 usually preferably 800 to 100,000. The number average molecular weight (Mn) of the vapor membrane breaker is a polystyrene-equivalent value measured by gel permeation chromatography (GPC). The content of the steam 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 treatment oil composition.

[0045] (Brilliance improver) Examples of the glitter improver include fats and oils; fatty acids; alkyl succinic acids such as alkyl succinimides; alkenyl succinic acids such as alkenyl succinimides; and substituted hydroxy aromatic carboxylic acid ester derivatives. 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 treatment oil composition.

[0046] (Antioxidants) Examples of the antioxidant include phenol-based antioxidants and amine-based antioxidants. Examples of the phenol-based antioxidant include monocyclic phenols such as 2,6-di-tert-butyl-4-methylphenol, 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; ,6-di-tert-butylphenol), 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 other polycyclic phenols; and the like. Examples of the amine-based antioxidant include diphenylamine-based antioxidants and naphthylamine-based antioxidants. Examples of diphenylamine-based antioxidants include alkylated diphenylamines having an alkyl group having 3 to 20 carbon atoms, and specific examples thereof include diphenylamine, monooctyldiphenylamine, monononyldiphenylamine, 4,4'-dibutyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldiphenylamine, tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, and tetranonyldiphenylamine. Examples of naphthylamine-based antioxidants include alkyl-substituted phenyl-α-naphthylamines having 3 to 20 carbon atoms, and specific examples thereof 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. The content of the antioxidant is preferably 0.01 mass % to 5.0 mass %, more preferably 0.05 mass % to 3.0 mass %, and even more preferably 0.1 mass % to 2.0 mass %, based on the total amount of the heat-treated oil composition.

[0047] (Detergent / dispersant) As the detergent-dispersant, for example, one or more types selected from the group consisting of metal-based detergents and ashless dispersants can be used. Metal detergents include, for example, 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 ashless dispersants include alkenyl succinimides, boron-containing alkenyl succinimides, benzylamines, boron-containing benzylamines, succinic acid esters, fatty acids, and mono- or di-carboxylic acid amides typified by succinic acid. These detergent-dispersants may be used alone or in combination of two or more. The content of the detergent-dispersant is 0.01% by mass to 5.0% by mass based on the total amount of the heat treatment oil composition.

[0048] (Sulfides other than sulfides (B1), sulfones other than sulfones (B2)) In one embodiment of the heat treatment oil composition of the present invention, other sulfides than the sulfide (B1) may be contained. However, from the viewpoint of making it easier to improve the luster of the metal material after heat treatment such as quenching, it is preferable that the content of the other sulfides is small. In one embodiment of the heat-treated oil composition of the present invention, the content of the other sulfides is preferably less than 0.2 mass%, more preferably less than 0.1 mass%, even more preferably less than 0.01 mass%, still more preferably less than 0.001 mass%, and even more preferably no other sulfides, based on the total amount of the heat-treated oil composition. The other sulfides include, for example, compounds represented by the above general formula (b1), 11 and R 12 and p=0.

[0049] In addition, the heat treatment oil composition of one embodiment of the present invention may contain sulfones other than the sulfone (B2). However, from the viewpoint of making it easier to improve the luster of the metal material after heat treatment such as quenching, it is preferable that the content of the other sulfones is small. In one embodiment of the heat treatment oil composition of the present invention, the content of the other sulfones is preferably less than 0.2 mass%, more preferably less than 0.1 mass%, even more preferably less than 0.01 mass%, still more preferably less than 0.001 mass%, and even more preferably no other sulfones are contained, based on the total amount of the heat treatment oil composition. The other sulfones include, for example, compounds represented by the above general formula (b2), 21 and R 22 or both of the above are aliphatic hydrocarbon groups.

[0050] [Physical properties of the heat treatment oil composition of the present invention] <Sulfur content> The heat-treated oil composition according to one embodiment of the present invention has a sulfur content of preferably 10 ppm by mass or more, more preferably 100 ppm by mass or more, and even more preferably 300 ppm by mass or more, based on the total amount of the heat-treated oil composition. Also, the heat-treated oil composition has a sulfur content of preferably 15,000 ppm by mass or less, more preferably 12,000 ppm by mass or less, and even more preferably 10,000 ppm by mass or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably 10 ppm by mass to 15,000 ppm by mass, more preferably 100 ppm by mass to 12,000 ppm by mass, and even more preferably 300 ppm by mass to 10,000 ppm by mass.

[0051] <40℃ kinematic viscosity> The heat treatment oil composition of one embodiment of the present invention has a 40° C. kinetic viscosity set according to the desired oil temperature during heat treatment such as quenching. Heat treatment 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 treatment oil composition of one embodiment of the present invention is used as a cold oil, the 40°C kinematic viscosity is 5mm 2 / s or more 40mm 2 It is preferable that the ratio is less than 1 / s. When the heat treatment oil composition according to one embodiment of the present invention is used as a semi-hot oil or a hot oil, the 40° C. kinematic viscosity is 40 mm 2 / s or more 500mm 2 It is more preferable that the ratio is equal to or less than 1 / s.

[0052] [Method of producing the heat treatment oil composition of the present invention] The method for producing the heat treatment oil composition of the present invention is not particularly limited. For example, a method for producing a heat treatment oil composition according to one embodiment of the present invention 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 one or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and sulfones (B2) represented by the following general formula (b2). [ka] [In the above general formula (b1), R 11 , R 12 , and R 13 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms; and p is 0 or 1.] [ka] [In the general formula (b2), R 21 and R 22 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.]

[0053] The method of mixing each of the above components is not particularly limited, and may be, for example, a method having a step of blending a sulfur-containing aromatic compound (B) with a base oil (A). When the heat treatment oil composition further contains other components other than the base oil (A) and the sulfur-containing aromatic compound (B), the other components may be blended simultaneously with the sulfur-containing aromatic compound (B) in the base oil (A), or may be blended separately. Each component may be blended after being made into a solution (dispersion) by adding a diluent oil or the like. After blending each component, it is preferable to stir and uniformly disperse them by a known method. The preferred embodiments of the base oil (A) and the sulfur-containing aromatic compound (B) are as described above.

[0054] [Uses of the heat treatment oil composition of the present invention] The heat treatment oil composition of the present invention can improve the luster of the metal material after heat treatment such as quenching by using it during heat treatment such as quenching of the metal material. For example, it 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. Therefore, the present invention provides a method for heat treating a metal material, in which the heat treatment oil composition of the present invention is used during heat treatment such as quenching of the metal material. In this case, the oil temperature of the heat treatment oil composition is preferably set to 60°C to 200°C, more preferably 60°C to 150°C, when the heat treatment is quenching. When the heat treatment is tempering, the oil temperature may be further increased, for example, the upper limit may be 250°C. In addition, the quenching temperature of the metal material may be 800°C or more and 900°C or less, or may be more than 900°C and 1000°C or less. According to the heat treatment oil composition of the present invention, even when the quenching temperature of the metal material is more than 900°C and 1000°C or less, the luster of the metal material after quenching can be improved.

[0055] [One aspect of the present invention provided] In one embodiment of the present invention, the following [1] to

[12] are provided. [1] One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); one or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and sulfones (B2) represented by the following general formula (b2); A heat treatment oil composition comprising: [ka] [In the above general formula (b1), R 11 , R 12 , and R 13 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms; and p is 0 or 1.] [ka] [In the general formula (b2), R 21 and R 22 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.] [2] In the general formula (b1), R 11 The heat treatment oil composition according to [1], wherein is a substituted or unsubstituted phenyl group. [3] In the general formula (b1), R 12 The heat treatment oil composition according to [1] or [2], wherein is a substituted or unsubstituted phenyl group. [4] In the general formula (b1), R 13 The heat treatment oil composition according to any one of [1] to [3], wherein is a substituted or unsubstituted phenyl group. [5] The heat treatment oil composition according to any one of [1] to [3], wherein, in the general formula (b1), p is 0. [6] In the general formula (b2), R 21 The heat treatment oil composition according to any one of [1] to [5], wherein is a substituted or unsubstituted phenyl group. [7] In the general formula (b2), R 22 The heat treatment oil composition according to any one of [1] to [6], wherein is a substituted or unsubstituted phenyl group. [8] The heat treatment oil composition according to any one of [1] to [7], wherein the molecular weight of the sulfur-containing aromatic compound (B) is 100 to 500. [9] The heat treatment oil composition according to any one of [1] to [8], having a sulfur content of 10 ppm by mass to 15,000 ppm by mass based on the total amount of the heat treatment oil composition.

[10] The heat treatment oil composition according to any one of [1] to [9], wherein the content of the sulfur-containing aromatic compound (B) is 0.02 mass% to 5.5 mass% based on the total amount of the heat treatment oil composition.

[11] The heat treatment oil composition according to any one of [1] to

[10] , further comprising one or more additives selected from the group consisting of a steam film breaker, a glitter improver, an antioxidant, and a detergent / dispersant.

[12] One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); one or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and sulfones (B2) represented by the following general formula (b2); A method for producing a heat treatment oil composition, comprising the step of mixing the above. [ka] [In the above general formula (b1), R 11 , R 12 , and R 13 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms; and p is 0 or 1.] [ka] [In the general formula (b2), R 21 and R 22 each independently represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.] EXAMPLES

[0056] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

[0057] [Methods for measuring various physical properties] (1) Kinematic viscosity at 40°C of base oil (A) and heat-treated oil composition The 40° C. kinematic viscosity 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.

[0058] [Examples 1 to 10, Comparative Examples 1 to 5] The raw materials used in preparing the heat-treated oil compositions of Examples 1 to 10 and Comparative Examples 1 to 5 are shown below.

[0059] (1) Base oil (A) Mineral oil (A1)-1 Mineral oil classified as Group III in API category, sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 12.53 mm 2 / s Mineral oil (A1)-2 Mineral oil classified as Group III in API category, sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 41.81 mm 2 / s Mineral oil (A1)-3 High viscosity mineral oil classified as Group II in API category, sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 396.7 mm 2 / s Mineral oil (A1)-4: High viscosity mineral oil classified as Group I in the API category (corresponding to Bright Stock (A1-2)), sulfur content: 1.12 mass%, kinematic viscosity at 40°C: 481.8 mm 2 / s Synthetic oil (A2)-1: GTL base oil classified as Group III in the API category, sulfur content: less than 3 ppm by mass, kinematic viscosity at 40°C: 9.640 mm 2 / s

[0060] (2) Sulfur-containing aromatic compound (B) Sulfides (B1)-1: Diphenyl sulfide (molecular weight: 186.27) It is a compound represented by the following chemical formula (b1-1). [ka] The compound represented by chemical formula (b1-1) is a compound represented by the general formula (b1), 11 and R 12 is an unsubstituted phenyl group (in the above general formula (bx), m=0), and p is 0.

[0061] Sulfides (B1)-2: Phenylbis(phenylthio)methane (molecular weight: 308.46) It is a compound represented by the following chemical formula (b1-2). [ka] The compound represented by chemical formula (b1-2) is a compound represented by the general formula (b1), 11 , R 12 , and R 13 is an unsubstituted phenyl group (in the above general formula (bx), m=0) and p=1.

[0062] Sulfides (B1)-3: 4,4'-thiobis(6-tert-butyl-m-cresol) (molecular weight: 358.54) It is a compound represented by the following chemical formula (b1-3). [ka] The compound represented by chemical formula (b1-3) is a compound represented by the general formula (b1), 11 and R 12 is a 6-tert-butyl-m-cresyl group (in the above general formula (bx), m=3, three R x1 are methyl, tert-butyl, and hydroxyl groups, respectively. The substitution position of the hydroxyl group is para to the sulfur atom, and p is 0.

[0063] Sulfides (B1)-4: 4-tert-butyldiphenyl sulfide (molecular weight: 242.38) It is a compound represented by the following chemical formula (b1-4). [ka] The compound represented by chemical formula (b1-4) is a compound represented by the general formula (b1), 11 is an unsubstituted phenyl group (in the general formula (bx) above, m=0), and R12 is a tert-butylphenyl group (in the above general formula (bx), m=1, R x1 is tert-butyl, the substitution position of tert-butyl is para to the sulfur atom), and corresponds to a compound in which p is 0.

[0064] Sulfones (B2)-1: Diphenyl sulfone (molecular weight: 218.27) 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 the general formula (b2), 21 and R 22 is an unsubstituted phenyl group (in the above general formula (bx), m=0).

[0065] (2') Sulfur-containing non-aromatic compound (B') Didodecyl sulfide (molecular weight: 370.72) It is a compound represented by the following chemical formula (b'). [ka] The compound represented by chemical formula (b') is a compound that does not fall under the general formula (b1) or the general formula (b2).

[0066] (3) Additives Steam film breaker, glitter enhancer, antioxidant (phenolic antioxidant)

[0067] The above raw materials were thoroughly mixed in the blending amounts (mass %) shown in Tables 1 to 5 to prepare the heat-treated oil compositions of Examples 1 to 10 and Comparative Examples 1 to 5, respectively.

[0068] <How to evaluate 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 prepare a test specimen. In detail, a dumbbell-shaped steel material S45C and a cylindrical steel material SUJ2 were tied at the center with a SUS303 wire to bind the dumbbell-shaped steel material S45C and the cylindrical steel material SUJ2 (see FIG. 1). Then, the test specimen was heated in a furnace with a mixed gas atmosphere of nitrogen and hydrogen, and then the test specimen was put into a heat treatment oil composition to perform quenching, and a quenching test was performed. The hardening test was carried out under the following four conditions.

[0069] (Quenching test condition 1: Cold oil test 1, Tables 1 to 3) Test subjects: Comparative Examples 1-2, Examples 1-8 Furnace temperature: 850℃ Time to hold the test piece in the furnace: 40 minutes after the furnace temperature reaches 850℃ Temperature of heat treatment oil composition: 80°C Immersion time of test piece in heat treatment oil composition (quenching time): 10 minutes

[0070] (Quenching test condition 2: Hot oil simulation test, Table 4) Test subjects: Comparative Examples 3 to 4, Example 9 Furnace temperature: 850℃ Time to hold the test piece in the furnace: 40 minutes after the furnace temperature reaches 850℃ Temperature of heat treatment oil composition: 120°C Immersion time of test piece in heat treatment oil composition (quenching time): 10 minutes

[0071] (Quenching test condition 3: Cold oil simulation test 2, Table 5) Test subjects: Comparative Example 5, Example 10 Furnace temperature: 975℃ Test piece retention time in furnace: 40 minutes after furnace temperature reaches 975℃ Temperature of heat treatment oil composition: 60°C Immersion time of test piece in heat treatment oil composition (quenching time): 10 minutes

[0072] After quenching, the test pieces were evaluated for luster based on the following criteria, focusing on "brightness," "coloring of the edge," and "coloring of the contact area." In addition, based on the evaluation results of "brightness," "coloring of the edge," and "coloring of the contact area," the luster of the test pieces was evaluated overall based on the following criteria. (brightness) A sample with a given color was prepared and the color of the test piece after quenching was compared visually. The degree of coloring of the 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 ends of the test pieces (see FIG. 1) were visually observed and evaluated according to the following criteria. 0: No or very little coloring. 1: Light coloring is observed. 2: Dark brown to black coloration is observed. (Coloring of contact parts) The test specimen (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 very little coloring. 1: Light coloring is observed. 2: Dark brown to black coloration is observed.

[0073] (Overall evaluation of brilliance) Using the evaluation results of "brightness," "coloration of edges," and "coloration of contact areas," a comprehensive evaluation was made based on the following criteria. S: 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," "coloring of edges," and "coloring of contact areas" 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 of "brightness," "coloring of the edge," and "coloring of the contact area" is 3 or more. However, if the evaluation result of any of "brightness," "coloring of edges," and "coloring of contact parts" was 2 or more, the evaluation was given a C. The heat-treated oil composition rated S has extremely excellent luster. The heat-treated oil composition rated A has excellent luster. On the other hand, the heat-treated oil composition rated B has slightly poor luster. The heat-treated oil composition rated C has poor luster.

[0074] The results are shown in Tables 1 to 5. In Tables 1 to 5, ">" means "less than." 2 shows test pieces after the quenching test using the heat treatment oil compositions of Examples 1 to 10, and FIG. 3 shows test pieces after the quenching test using the heat treatment oil compositions of Comparative Examples 1 to 5.

[0075] [Table 1] [Table 2] [Table 3] [Table 4] [Table 5]

[0076] The following can be seen from Tables 1 to 5. It is clear that the heat treatment oil compositions of Examples 1 to 10, which contain the sulfur-containing aromatic compound (B), can provide good luster to the test pieces after quenching. In contrast, it is found that the heat treatment oil compositions of Comparative Examples 1 to 5, which do not contain the sulfur-containing aromatic compound (B), reduce the luster of the test piece after quenching. Also, it is found that the heat treatment oil composition of Comparative Example 4, which contains sulfides in which a linear alkyl group is bonded to a sulfur atom and an aromatic group is not bonded to a sulfur atom, reduces the luster of the test piece after quenching.

[0077] <Study on sludge generation> The heat treatment oil compositions of Example 5 and Comparative Example 1 were examined for sludge generation. Specifically, the heat-treated oil compositions of Example 5 and Comparative Example 1 were subjected to forced deterioration, and the generation of sludge was examined. The forced deterioration method was based on the Indiana Oxidation Test (IOT) under the following conditions. ·Oil temperature: 170℃ Air flow rate: 10L / min Catalyst: Combination of iron (Fe) and copper (Cu) Forced aging time: 48 hours, 96 hours The insoluble matter and residual carbon matter were measured for oils that had been aged for 48 hours and for oils that had been aged for 96 hours, and the amount of sludge generated was evaluated. The greater the insoluble matter and residual carbon matter, the greater the amount of sludge generated, and conversely, the smaller the amount of sludge generated, the less the amount of sludge generated. The insoluble matter was measured according to ASTM D893-14(2018). The carbon residue was measured in accordance with JIS K 2270-2:2009. The results are shown in Table 6.

[0078] [Table 6]

[0079] The results shown in Table 6 reveal the following: It is clear that the heat-treated oil composition of Example 5 has a small amount of insoluble matter and residual carbon after forced aging, and thus suppresses the generation of sludge. In contrast, the heat-treated oil composition of Comparative Example 1 has a large amount of insoluble matter and residual carbon after forced aging, and thus generates a large amount of sludge. Neither the heat-treated oil composition of Example 5 nor the heat-treated oil composition of Comparative Example 1 contained an antioxidant. Therefore, the amount of sludge generated was large in the heat-treated oil composition of Comparative Example 1, but the amount of sludge generated was suppressed in the heat-treated oil composition of Example 5. This shows that by adding a sulfur-containing aromatic compound (B) such as a sulfide (B1), an excellent antioxidant effect is exerted and the generation of sludge can be suppressed.

Claims

1. One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); one or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and sulfones (B2) represented by the following general formula (b2), A heat treatment oil composition comprising: The content of the sulfur-containing aromatic compound (B) is 0.08 to 5.5 mass% based on the total amount of the heat treatment oil composition. 【Chemistry 1】 [In the general formula (b1), R １１ and R １２ are each independently a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. When the aryl group has a substituent, the substituent is one or more selected from the group consisting of an aliphatic hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group. p is 0.] 【Chemistry 2】 [In the general formula (b2), R ２１ and R ２２ are each independently a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.

2. In the general formula (b1), R １１ The heat treatment oil composition according to claim 1 , wherein is a substituted or unsubstituted phenyl group.

3. In the general formula (b1), R １２ The heat treatment oil composition according to claim 1 or 2, wherein is a substituted or unsubstituted phenyl group.

4. The heat treatment oil composition according to any one of claims 1 to 3, wherein the sulfur-containing aromatic compound (B) is one or more selected from the group consisting of the sulfides (B1).

5. One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); One or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1): A heat treatment oil composition comprising: 【Chemistry 3】 [In the general formula (b1), R 11 and R 12 are each independently a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, and R 13 is a substituted or unsubstituted phenyl group. When the aryl group or phenyl group has a substituent, the substituent is one or more selected from the group consisting of an aliphatic hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group. p is 1.]

6. One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); One or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfones (B2) represented by the following general formula (b2): A heat treatment oil composition comprising: 【Chemistry 4】 [In the general formula (b2), R 21 is a substituted or unsubstituted phenyl group, and R 22 is a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.]

7. One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); One or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfones (B2) represented by the following general formula (b2): A heat treatment oil composition comprising: 【Chemistry 5】 [In the general formula (b2), R 21 is a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, and R 22 is a substituted or unsubstituted phenyl group.]

8. The heat treatment oil composition according to any one of claims 1 to 7, wherein the molecular weight of the sulfur-containing aromatic compound (B) is 100 to 500.

9. The heat treatment oil composition according to any one of claims 1 to 8, wherein the sulfur content is 10 ppm by mass to 15,000 ppm by mass based on the total amount of the heat treatment oil composition.

10. The content of the sulfur-containing aromatic compound (B) is 0.08 mass% to 5.0 mass% based on the total amount of the heat treatment oil composition. The heat treatment oil composition according to any one of claims 1 to 9.

11. The heat treatment oil composition according to any one of claims 1 to 10, further comprising one or more additives selected from the group consisting of steam film breakers, glitter improvers, antioxidants, and detergent-dispersants.

12. One or more base oils (A) selected from the group consisting of mineral oils (A1), synthetic oils (A2), and vegetable oils (A3); one or more sulfur-containing aromatic compounds (B) selected from the group consisting of sulfides (B1) represented by the following general formula (b1) and sulfones (B2) represented by the following general formula (b2), A method for producing a heat treatment oil composition, comprising the step of mixing: The heat treatment oil composition is produced by mixing the sulfur-containing aromatic compound (B) so that the content of the sulfur-containing aromatic compound (B) is 0.08 to 5.5 mass% based on the total amount of the heat treatment oil composition. 【Chemistry 6】 [In the general formula (b1), R １１ and R １２ are each independently a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. When the aryl group has a substituent, the substituent is one or more selected from the group consisting of an aliphatic hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group. p is 0.] 【Chemistry 7】 [In the general formula (b2), R ２１ and R ２２ are each independently a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.

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