Base oil

Abstract

To provide a base oil that has excellent oxidation stability and luster and is usable as a heat treatment oil.SOLUTION: A base oil contains a sulfide compound, having a sulfur content of 0.05-0.70 mass%, a %CA of 0.50-2.00 as determined by n-d-M ring analysis and a kinematic viscosity of 17-25 mm2 / s at 40°C.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a base oil and a heat treatment oil composition containing the base oil. [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] 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] JP 2010-209422 A Summary of the Invention [Problem to be solved by the invention]

[0006] Traditionally, mineral oils belonging to Group 1 in the classification by the American Petroleum Institute (hereinafter referred to as API classification) have been used as base oils, but in recent years they are being replaced by Group 3 mineral oils, which are highly refined and modified and have excellent oxidation stability. However, the conditions for use of heat treatment oils are strict (see JIS K 2242:2012), and it has been found that the oxidation stability tends to be better when Group 1 mineral oils are used as base oils than when Group 3 mineral oils are used. In addition, it has been found that satisfactory performance cannot be achieved with regard to brilliance, which is an important performance factor for heat treatment oils, when only Group 3 mineral oils are used as base oils.

[0007] An object of the present invention is to provide a base oil which is excellent in oxidation stability and luster and can also be used as a heat treatment oil under severe operating conditions. [Means for solving the problem]

[0008] As a result of extensive research, the inventors have discovered that by using a base oil containing a specific sulfur content and a specific cyclic component in predetermined amounts and having a kinematic viscosity at 40°C within a specified range, it is possible to obtain a base oil that is excellent in oxidation stability and luster and can be used as a heat treatment oil, and have completed the present invention.

[0009] That is, the present invention [1] Contains a sulfide compound and has a sulfur content of 0.05 to 0.70% by mass; %C by ndM ring analysis A is 0.50 to 2.00, and the kinematic viscosity at 40°C is 17 to 25 mm 2 / s base oil, [2] Sulfur content (mass%) vs. %C by ndM ring analysis A The base oil according to the above [1], wherein the ratio of [3] Sulfur content (mass%) vs. %C by ndM ring analysis A The base oil according to the above [1], wherein the ratio of [4] The base oil according to any one of the above [1] to [3], wherein the sulfide compound is at least one selected from the group consisting of a dialkyl sulfide compound, a diaryl sulfide compound, an aryl alkyl sulfide compound, and a cyclic sulfide compound. [5] The base oil according to any one of the above [1] to [4], having a refractive index at 20°C of 1.45 to 1.48. [6] Density at 20°C is 0.835 to 0.840 g / cm 3 The base oil according to any one of the above items [1] to [5], [7] The base oil according to any one of the above [1] to [6], having a flash point of 180 to 240°C. [8] The base oil according to any one of [1] to [7] above, which is a base oil for heat treatment oil. [9] A heat treatment oil composition comprising the base oil according to any one of [1] to [7] above and at least one selected from the group consisting of a cooling performance improver, a glitter improver, an antioxidant, and an antifoaming agent. Effect of the Invention

[0010] According to the present invention, there is provided a base oil which is excellent in oxidation stability and luster and can be used as a heat treatment oil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Base oil> The base oil according to the present embodiment contains a sulfide compound, has a sulfur content of 0.05 to 0.70 mass%, and is %C by ndM ring analysis. A is 0.50 to 2.00, and the kinematic viscosity at 40°C is 17 to 25 mm 2 / s. The base oil according to this embodiment will be described in detail below. However, the following description is an example for explaining this embodiment, and is not intended to limit the technical scope of the present invention to only this described range. In this specification, when a numerical range is indicated using "~", the numerical values ​​at both ends are included.

[0012] The base oil according to the present embodiment preferably contains a mineral oil. Examples of the mineral oil include atmospheric residual oil obtained by atmospheric distillation of crude oil such as paraffin-based crude oil, intermediate-based crude oil, and naphthene-based crude oil; distillate oil obtained by vacuum distillation of the atmospheric residual oil; and mineral oil obtained by subjecting the distillate oil to one or more refining treatments such as solvent deasphalting, solvent extraction, hydrofinishing, hydrocracking, advanced hydrocracking, solvent dewaxing, catalytic dewaxing, and hydroisomerization dewaxing. Specific examples of the mineral oil include paraffin-based mineral oil and naphthene-based mineral oil. These mineral oils may be used alone or in combination of two or more.

[0013] The base oil according to the present embodiment may contain a base oil other than mineral oil according to its application and purpose, within a range that does not impair the effects of the present invention. The base oil other than mineral oil is not particularly limited, but may be, for example, synthetic hydrocarbon oil, synthetic ester oil, vegetable oil, animal oil, polyglycol-based synthetic oil, phenyl ether-based synthetic oil, silicone-based synthetic oil, fluorine-based synthetic oil, etc. These base oils other than mineral oil may be used alone or in combination of two or more.

[0014] The content of mineral oil in the base oil is preferably 80 mass % or more, more preferably 90 mass % or more, further preferably 95 mass % or more, and particularly preferably 98 mass % or more. The base oil may consist of mineral oil alone.

[0015] The base oil according to the present embodiment contains a sulfide compound as a sulfur content in order to improve the luster. Examples of the sulfide compound include the sulfide compounds contained in mineral oils belonging to Group 1 in the API classification, and specifically, for example, one or more selected from the group consisting of dialkyl sulfide compounds, diaryl sulfide compounds, aryl alkyl sulfide compounds, and cyclic sulfide compounds. Note that, when the sulfur content is composed only of elemental sulfur, sufficient luster tends not to be obtained.

[0016] The sulfur content in the base oil is 0.05% by mass or more, preferably 0.07% by mass or more, more preferably 0.09% by mass or more, and even more preferably 0.11% by mass or more, from the viewpoint of improving oxidation stability and brilliance. On the other hand, the sulfur content in the base oil is 0.70% by mass or less, preferably 0.50% by mass or less, more preferably 0.40% by mass or less, and even more preferably 0.30% by mass or less, from the viewpoint of suppressing sludge formation. In this specification, the sulfur content in the base oil is measured in accordance with the wavelength dispersive X-ray fluorescence method of JIS K 2541-7:2013.

[0017] %C by ndM ring analysis of base oil A From the viewpoint of improving the solubility of the additive, the %C by the ndM ring analysis of the base oil is 0.50 or more, preferably 0.60 or more, more preferably 0.70 or more, and even more preferably 0.80 or more. A From the viewpoint of suppressing sludge generation and improving brightness, %C is 2.00 or less, preferably 1.80 or less, more preferably 1.60 or less, and even more preferably 1.50 or less. A is an index representing the aromatic content determined by ring analysis.

[0018] %C by ndM ring analysis against sulfur content (mass%) in base oil A From the viewpoint of the effects of the present invention, the ratio of %C to the sulfur content (mass%) in the base oil by ndM ring analysis is preferably 4.0 or more, more preferably 4.5 or more, even more preferably 5.0 or more, and particularly preferably 5.5 or more. A In view of the effects of the present invention, the ratio is preferably 30 or less, more preferably 26 or less, even more preferably 22 or less, still more preferably 18 or less, and particularly preferably 14 or less.

[0019] The kinematic viscosity of the base oil at 40°C is set to 17mm in order to increase the flash point. 2 / s or more, 18 mm 2 / s or more is preferable, 19mm 2 / s or more is preferable, and 20 mm 2On the other hand, from the viewpoint of improving the cooling performance, the kinetic viscosity of the base oil at 40°C is preferably 25mm / s or more. 2 / s or less, 24 mm 2 / s or less is preferable, 23 mm 2 / s or less is preferable, and 22 mm 2 In this specification, the kinematic viscosity of the base oil at 40° C. is measured in accordance with JIS K 2283:2000.

[0020] The refractive index of the base oil at 20°C is preferably 1.48 or less, more preferably 1.47 or less, from the viewpoint of securing a base oil having an appropriate viscosity upper limit and from the viewpoint of securing a base oil having an appropriate viscosity lower limit. The lower limit of the refractive index of the base oil at 20°C is not particularly limited, but is preferably 1.43 or more, more preferably 1.44 or more, and even more preferably 1.45 or more. In this specification, the refractive index of the base oil at 20°C is measured in accordance with ASTM D1218-92.

[0021] The density of the base oil at 20°C is set to 0.833 g / cm in order to ensure that the base oil has an appropriate lower limit of viscosity. 3 More than 0.835 g / cm is preferable. 3 More preferably, 0.836 g / cm 3 On the other hand, the density of the base oil at 20° C. is preferably 0.844 g / cm from the viewpoint of ensuring a base oil having an appropriate upper viscosity limit. 3 Less than 0.842 g / cm is preferred. 3 Less than 0.840 g / cm is more preferable. 3 The following is more preferable. In this specification, the density of the base oil at 20° C. is measured in accordance with JIS K 2249-1:2011.

[0022] From the perspective of safety, the flash point of the base oil is preferably 180 °C or higher, more preferably 190 °C, still more preferably 200 °C or higher, and particularly preferably 205 °C or higher. On the other hand, the upper limit value of the flash point of the base oil is not particularly limited, but for example, it can be 240 °C or lower, 235 °C or lower, or 230 °C or lower. In this specification, the flash point of the base oil conforms to JIS K 2265-4:2007 and is measured by the Cleveland Open Cup method (COC method).

[0023] The base oil according to this embodiment can be obtained by mixing commercially available mineral oils or mineral oils produced by known methods. For example, it can be obtained by mixing a mineral oil belonging to Group 1 and a mineral oil belonging to Group 3 in the API classification. Further, depending on its use and purpose, base oils other than the above-mentioned mineral oils may be further mixed within a range that does not impair the effects of the present invention.

[0024] <Heat treatment oil composition> The above base oil is preferably used as a base oil for heat treatment oil. The heat treatment oil composition according to this embodiment can be obtained by mixing the above base oil and additives commonly used in heat treatment oil by a known method. Examples of such additives include a cooling performance improver, a brightness improver, an antioxidant, an antifoaming agent, and the like. These additives may be used alone or in combination of two or more.

[0025] Examples of the cooling performance improver include asphalt; asphaltene; synthetic polymer; metal sulfonates such as magnesium sulfonate, calcium sulfonate, calcium sulfonate complex, zinc sulfonate, and barium sulfonate; metal salicylates such as calcium salicylate; metal phenates such as calcium phenate; alkenyl succinimides; boron-containing alkenyl succinimides, and the like. These cooling performance improvers may be used alone or in combination of two or more.

[0026] When the heat treatment oil composition contains a cooling performance improver, the content in the heat treatment oil composition is preferably 0.01 to 8.0% by mass, and more preferably 0.1 to 5.0% by mass.

[0027] Examples of the glitter improver include fats and oils; fatty acids; alkyl succinic acid, alkyl succinimide, alkyl succinic anhydride, and derivatives thereof; alkenyl succinic acid, alkenyl succinimide, alkenyl succinic anhydride, and derivatives thereof; substituted hydroxy aromatic carboxylic acid esters and derivatives thereof, etc. These glitter improvers may be used alone or in combination of two or more.

[0028] When a glitter improver is contained, the content thereof in the heat treatment oil composition is preferably from 0.1 to 5.0 mass %, and more preferably from 0.3 to 3.0 mass %.

[0029] Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, etc. These antioxidants may be used alone or in combination of two or more.

[0030] Examples of the phenol-based antioxidant 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; 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;

[0031] Examples of the amine-based antioxidant include diphenylamine-based antioxidants, naphthylamine-based antioxidants, etc. Examples of the diphenylamine-based antioxidant 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 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.

[0032] When an antioxidant is contained, the content in the heat treatment oil composition is preferably 0.01 to 5.0 mass %, more preferably 0.05 to 4.0 mass %.

[0033] Examples of the antifoaming agent include methylsilicone oil, fluorosilicone oil, polyacrylate, etc. These antifoaming agents may be used alone or in combination of two or more kinds.

[0034] When an antifoaming agent is contained, the content in the heat treatment oil composition is preferably 0.01 to 5.0 mass %, and more preferably 0.05 to 4.0 mass %.

[0035] The total content of the additives in the heat treatment oil composition is preferably from 0.01 to 20.0 mass %, more preferably from 0.05 to 15.0 mass %.

[0036] The kinetic viscosity of the heat treatment oil composition at 40°C is 26mm, in accordance with the quality and properties standard set forth in JIS K 2242:2012. 2 In this specification, the kinematic viscosity at 40° C. of the heat treatment oil composition is measured in accordance with JIS K 2283:2000.

[0037] The characteristic temperature of the heat treatment oil composition is preferably 580° C. or higher, based on the standards for quality and properties set forth in JIS K 2242: 2012. In this specification, the characteristic temperature of the heat treatment oil composition is measured in accordance with JIS K 2242: 2012.

[0038] The cooling time of the heat treatment oil composition from 800°C to 400°C is preferably 4.0 seconds or less, based on the quality and properties criteria set forth in JIS K 2242: 2012. In this specification, the cooling time of the heat treatment oil composition from 800°C to 400°C is measured in accordance with JIS K 2242: 2012.

[0039] The heat treatment oil composition according to the present embodiment 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 is 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, manganese steel, etc.

[0040] The heat treatment oil composition according to the present embodiment can be used for heat treatment of metal members. Heat treatment of metal members can be carried out, for example, by immersing the heated metal members in the heat treatment oil composition with the oil temperature maintained at 40 to 100° C., and then cooling them. EXAMPLES

[0041] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0042] In this example, the following raw materials were used: Mineral oil 1 (obtained by solvent extraction of the lubricating oil fraction obtained by vacuum distillation of naphthenic crude oil, kinematic viscosity at 40°C (mm 2 / s): 18.71, Sulfur content (mass%): 0.00, Aromatic content (%C A ):0.00) Mineral oil 2 (obtained by solvent extraction of the lubricating oil fraction obtained by vacuum distillation of naphthenic crude oil, kinematic viscosity at 40°C (mm 2 / s): 31.70, Sulfur content (mass%): 0.00, Aromatic content (%C A ):0.00) Mineral oil 3 (obtained by solvent extraction of the lubricating oil fraction obtained by vacuum distillation of naphthenic crude oil, kinematic viscosity at 40°C (mm 2 / s): 23.69, contains sulfide compounds, sulfur content (mass%): 0.71, aromatic content (%C A ):4.19) Mineral oil 4 (obtained by solvent extraction of the lubricating oil fraction obtained by vacuum distillation of naphthenic crude oil, kinematic viscosity at 40°C (mm 2 / s): 24.16, contains sulfide compounds, sulfur content (mass%): 0.46, aromatic content (%C A ):3.21) Mineral oil 5 (obtained by solvent extraction of the lubricating oil fraction obtained by vacuum distillation of naphthenic crude oil, kinematic viscosity at 40°C (mm 2 / s): 28.66, contains sulfide compounds, sulfur content (mass%): 0.30, aromatic content (%C A ):6.59) Mineral oil 6 (obtained by solvent extraction of the lubricating oil fraction obtained by vacuum distillation of naphthenic crude oil, kinematic viscosity at 40°C (mm 2 / s): 27.52, contains sulfide compounds, sulfur content (mass%): 0.14, aromatic content (%C A ):2.00) Mineral oil 7 (obtained by solvent extraction of the lubricating oil fraction obtained by vacuum distillation of naphthenic crude oil, kinematic viscosity at 40°C (mm 2 / s): 43.19, Sulfur content (mass%): 0.00, Aromatic content (%C A ):12.1) Sulfur: Finely divided sulfur produced by Hosoi Chemical Industry Co., Ltd.

[0043] The above raw materials were thoroughly mixed at the compounding amounts (mass %) shown in Table 1 to prepare the mixed base oils of Examples 1 to 3 and Comparative Examples 1 to 5, and the oxidation stability and brightness were evaluated by the following methods.

[0044] <Oxidation stability> In accordance with the "6.3 Stability Test Method" of JIS K 2242:2012, the base oil was oxidized and deteriorated by the following method. 300 mL of the base oil was charged into a container with a capacity of 420 mL (φ40 mm × length 450 mm), and without charging a catalyst, it was oxidized and deteriorated at a temperature of 165 °C and an air flow rate of 10 L / h for 48 hours. Then, for the base oil that has not been oxidized and deteriorated (hereinafter also referred to as "new oil") and the base oil after oxidation and deterioration, the kinematic viscosity at 40 °C was measured respectively, and the increase rate of the kinematic viscosity at 40 °C after oxidation and deterioration (the increase rate of the kinematic viscosity at 40 °C from the new oil) was calculated by the following formula. The smaller the increase rate of the kinematic viscosity at 40 °C from the new oil, the less likely the oxidation and deterioration of the base oil progresses, meaning higher oxidation stability. (Increase rate of kinematic viscosity at 40 °C from new oil (%)) = [(Kinematic viscosity at 40 °C of the base oil after oxidation and deterioration) - (Kinematic viscosity at 40 °C of the new oil)] / (Kinematic viscosity at 40 °C of the new oil) × 100

[0045] <Brightness> With reference to "Masayoshi Taga, Imio Tamura, Metal Surface Technology, VOL.77, No.7, P261 (1956)", the brightness of the heat-treated steel was evaluated. In a furnace with a mixed gas atmosphere of argon and hydrogen, a test piece made of a cylindrical steel material SUJ2 (high-carbon chromium bearing steel material described in JIS G 4805, diameter: 15 mm, length: 25 mm, hardness HRC: 8) was heated, and then the test piece was put into the heat treatment oil composition for quenching, and a quenching test was carried out. The conditions of the quenching test were the following 4 conditions.

[0046] (Cold oil assumed test) Furnace temperature: 850 °C Holding time of the test piece in the furnace: 15 minutes after the furnace temperature reaches 850 °C Temperature of the heat treatment oil: 70 °C Immersion time of the test piece in the heat treatment oil (quenching time): 5 minutes

[0047] (Evaluation of brilliance) The luster was evaluated according to the following criteria based on the proportion of the white glossy area of ​​the test piece after quenching. The heat treatment oil composition with rating A has excellent luster. The heat treatment oil composition with rating B has slightly inferior luster. The heat treatment oil composition with rating C has many colored areas and low luster. Grade A: The area of ​​the white glossy part is 75% or more Grade B: The area of ​​the white glossy part is 55% or more but less than 75% Grade C: The area of ​​the white glossy area is less than 55%

[0048] [Table 1]

[0049] <Evaluation of heat treatment oil composition> A cooling performance improver was added to the base oil of Example 2 to prepare a heat-treated oil composition. The content of the cooling performance improver in the heat-treated oil composition was 3.0 mass %. The heat-treated oil composition (40°C kinematic viscosity (mm 2 The characteristic temperature (cooling time: 615°C, cooling time from 800°C to 400°C: 2.6 seconds) was sufficient for cooling. The brilliance was evaluated as A according to the above evaluation method. [Industrial Applicability]

[0050] The base oil of the present invention is excellent in oxidation stability and luster, and is useful as a base oil that can also be used as a heat treatment oil under severe operating conditions.

Claims

1. Contains sulfide compounds, The sulfur content is 0.05 to 0.70% by mass, %C by ndM ring analysis A is 0.50 to 2.00, Dynamic viscosity at 40°C is 17 to 25 mm 2 / s.

2. Sulfur content (mass%) by ndM ring analysis %C A The base oil of claim 1, wherein the ratio of

3. Sulfur content (mass%) by ndM ring analysis %C A The base oil of claim 1, wherein the ratio of

4. The base oil according to any one of claims 1 to 3, wherein the sulfide compound is at least one selected from the group consisting of a dialkyl sulfide compound, a diaryl sulfide compound, an aryl alkyl sulfide compound, and a cyclic sulfide compound.

5. The base oil according to any one of claims 1 to 3, having a refractive index at 20°C of 1.45 to 1.

48.

6. Density at 20°C: 0.835 to 0.840 g / cm 3 The base oil according to any one of claims 1 to 3,

7. The base oil according to any one of claims 1 to 3, having a flash point of 180 to 240°C.

8. The base oil according to claim 1, which is a base oil for heat treatment oil.

9. A heat treatment oil composition comprising the base oil according to claim 1 and at least one selected from the group consisting of a cooling performance improver, a glitter improver, an antioxidant and an antifoaming agent.

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