Base oil for metalworking oil composition and metalworking oil composition

Abstract

The present invention provides a base oil for a metalworking oil composition, which is a hydrocarbon having a flash point of less than 70 DEG C and a proton ratio of a methyl group of 20-65 (inclusive) when the integral value of all protons detected by 1H-NMR analysis is 100.

Description

Technical Field

[0001] The present invention relates to a base oil for a metalworking oil composition and the metalworking oil composition.

[0002] This application claims priority based on Japanese Patent Application No. 2022-109825 filed in Japan on July 7, 2022, and the contents are incorporated herein by reference. Background Art

[0003] Conventionally, in the field of metalworking, metalworking oil compositions are used to lubricate the processed parts of metal workpieces. Metalworking oil compositions are required to have good processability such as suppressing seizure between the workpiece and the tool.

[0004] As the metalworking oil composition, there can be used a composition containing a lubricating base oil and additives such as fatty acids, fatty acid esters, higher alcohols, and α-olefins.

[0005] However, conventional metalworking oil compositions have not been able to provide sufficient processability and have visible damage to the surface of the raw material. If the content of additives is increased to solve these problems, in addition to incomplete removal of the additives by heat, appearance problems such as discoloration, increased odor, deterioration of the working environment, and increased processing oil costs.

[0006] In addition, the processing oil attached to the workpiece after processing needs to be removed by heating. Therefore, the processing oil is required to have a certain volatility. However, if the volatility of the processing oil is improved, the processing oil will evaporate before and during processing, and sufficient processing performance will not be obtained. Therefore, the processing oil is required to have the opposite performance of volatilizing quickly and fully in the processing oil removal process (good removability), but not volatilizing easily at room temperature.

[0007] Patent Document 1 discloses a lubricating oil for pressing, characterized in that it contains 99.9 to 98 parts by mass of a base oil having an aniline point of 70° C. or higher and 0.01 to 2.0 parts by mass of a specific additive, and has a kinematic viscosity of 1.1 to 100 mm 2 / s (at 40°C). In addition, in the examples of Patent Document 1, polyisobutylene is disclosed as a base oil. It is disclosed that the lubricating oil for pressing has good lubricity and the like.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2011-252100 Summary of the invention

[0011] Problems to be solved by the invention

[0012] The conventional metalworking oil composition described in Patent Document 1 has room for improvement in terms of the balance between processability and removability.

[0013] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a base oil for a metalworking oil composition and a metalworking oil composition having excellent machinability and removability.

[0014] Means for solving problems

[0015] In order to solve the above-mentioned problems, the present invention adopts the following configuration.

[0016] [1] A base oil for a metalworking oil composition having a flash point of less than 70°C and 1 A hydrocarbon having a proton ratio of the methyl group of 20 or more and 65 or less when the integrated value of all protons detected by H-NMR analysis is set to 100.

[0017] [2] A base oil for a metalworking oil composition according to [1], wherein, in a carbon number distribution obtained by gas chromatography distillation, the ratio (CB / CA) of the proportion of hydrocarbons with the largest carbon number (CA) to the proportion of hydrocarbons with the second largest carbon number (CB) is not more than 0.5.

[0018] [3] The base oil for a metalworking oil composition according to [1] or [2], wherein the proportion (CC) of hydrocarbons having a carbon number of 10 or less in the carbon number distribution obtained by gas chromatography distillation is 20% or more.

[0019] [4] A metalworking oil composition comprising the base oil for a metalworking oil composition according to any one of [1] to [3].

[0020] [5] The metalworking oil composition according to [4], which is used for press working of metal.

[0021] Effects of the Invention

[0022] According to the present invention, a base oil for a metalworking oil composition and a metalworking oil composition having excellent machinability and removability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is an explanatory diagram schematically showing a flat plate sliding test. DETAILED DESCRIPTION

[0024] (Base oil for metalworking oil composition)

[0025] The base oil for a metalworking oil composition according to the present embodiment is the most suitable base oil for use as a base oil of a metalworking oil composition for lubricating a processing portion of a workpiece made of metal.

[0026] As the base oil for the metalworking oil composition, mineral oil or the like is used.

[0027] As the mineral oil, a distillate obtained by distilling crude oil under normal pressure can be used, or a lubricating oil fraction obtained by further distilling the distillate under reduced pressure and refining the distillate using various refining processes can be used.

[0028] As the refining process, it is possible to appropriately combine hydrotreating, solvent extraction, solvent dewaxing, hydrodewaxing, sulfuric acid washing, clay treatment, etc. By combining these refining processes in an appropriate order, mineral oil can be obtained.

[0029] Alternatively, a mixture of a plurality of refined oils having different properties obtained by subjecting different crude oils or distillate oils to a combination of different refining processes may be used.

[0030] The flash point of the base oil for the metalworking oil composition of this embodiment is less than 70°C, preferably 65°C or less, more preferably 60°C or less. The lower limit of the flash point is not particularly limited, and may be, for example, 21°C or more, 25°C or more, or 30°C or more.

[0031] Since the base oil for the metalworking oil composition of this embodiment has a flash point of less than 70°C, that is, since it contains hydrocarbons with a relatively small carbon number, the additives used together become more easily adsorbed on the surface of the workpiece, thereby improving the workability. In addition, hydrocarbons with a relatively small carbon number evaporate more easily, so the removability is also improved.

[0032] In this specification, the flash point of the base oil for a metalworking oil composition refers to a value measured by the Pensky-Marten closed method specified in JIS K2265-3:2007.

[0033] The base oil for the metalworking oil composition of this embodiment is 1 A hydrocarbon having a methyl group proton ratio of 20 to 65 when the integrated value of all protons detected by H-NMR analysis is 100. The base oil for a metalworking oil composition in one embodiment contains isoparaffin with relatively few branches as a main component.

[0034] In the base oil for the metalworking oil composition of the present embodiment, the proton ratio of the methyl group is 65 or less, preferably 60 or less, more preferably 45 or less, and further preferably 35 or less.

[0035] On the other hand, in the base oil for the metalworking oil composition of the present embodiment, the proton ratio of the methyl group is 20 or more, preferably 25 or more, and more preferably 30 or more.

[0036] When the proton ratio of the methyl group of the base oil for a metalworking oil composition is less than 20, that is, when the branch chain of the base oil is less, it is estimated that a plurality of molecules of the base oil are densely stacked, and the additive used is difficult to be adsorbed on the surface of the workpiece. On the other hand, when the proton ratio of the methyl group of the base oil for a metalworking oil composition exceeds 65, that is, when the branch chain of the base oil is more, it is estimated that the gaps between the molecules of the base oil become less, and the additive used is difficult to be adsorbed on the surface of the workpiece.

[0037] When the proton ratio of the methyl group of the base oil for a metalworking oil composition is within the above-mentioned preferred numerical range, that is, when the branching of the base oil is appropriate, it is estimated that the multiple molecules of the base oil become inconsistent, the gaps between the multiple molecules of the base oil increase, and the additives used become more easily adsorbed on the surface of the workpiece.

[0038] When the proton ratio of the methyl group of the base oil for a metalworking oil composition is within the above-mentioned preferred numerical range, it is estimated that the molecules are spaced apart from each other, so that the intermolecular force is reduced and the energy required for evaporation is reduced.

[0039] Therefore, by setting the proton ratio of the methyl group of the base oil for the metalworking oil composition of the present embodiment to be within the above-mentioned preferred numerical range, the processability and removability are improved.

[0040] For example, the proton ratio of the methyl group of the base oil for the metalworking oil composition of the present embodiment is preferably 25 or more and 60 or less, more preferably 30 or more and 45 or less, and even more preferably 30 or more and 35 or less.

[0041] 1 The measuring apparatus and measuring conditions for H-NMR measurement are as follows.

[0042] Equipment used: AVANCEⅢHD-cryo 600 NMR manufactured by Bruker

[0043] 1 H resonance frequency: 600.18MHz

[0044] Solvent: CDCl3

[0045] Concentration: about 50mg / mL

[0046] Determination method: 1 H non-decoupling method

[0047] Pulse width: 30° pulse

[0048] Waiting time: 5 seconds

[0049] Chemical shift standard: CHCl3 in CDCl3 (7.28 ppm)

[0050] When the base oil for the metalworking oil composition of the present embodiment is a mineral oil, the proton ratio of the methyl group in the base oil for the metalworking oil composition of the present embodiment can be controlled by appropriately managing the selection of crude oil and the refining conditions (temperature, pressure, catalyst, etc.) during the refining of the fractions obtained by atmospheric distillation and / or vacuum distillation of the crude oil, such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrotreating, sulfuric acid washing, clay treatment, etc.

[0051] When the base oil for the metalworking oil composition of the present embodiment is GTL or CTL, the proton ratio of the methyl group in the base oil for the metalworking oil composition of the present embodiment can be controlled by appropriately managing the reaction conditions (temperature, pressure, catalyst, etc.) of the FT reaction.

[0052] The base oil for the metalworking oil composition of the present embodiment is preferably a hydrocarbon having 6 to 20 carbon atoms, and more preferably a hydrocarbon having 6 to 18 carbon atoms.

[0053] Furthermore, the base oil for the metalworking oil composition of the present embodiment is preferably a mixture of hydrocarbons having different carbon numbers.

[0054] The carbon number of hydrocarbons in the present invention refers to the carbon number obtained by gas chromatography distillation described later.

[0055] In the base oil for the metalworking oil composition of the present embodiment, in the carbon number distribution, the ratio (CB / CA) of the proportion of hydrocarbons with the largest carbon number (CA) to the proportion of hydrocarbons with the second largest carbon number (CB) is preferably 0.5 or less, more preferably 0.3 or less, further preferably 0.2 or less, and particularly preferably 0.1 or less.

[0056] By setting the (CB / CA) to be equal to or less than the above-mentioned preferred value, the removability is further improved.

[0057] The ratio of hydrocarbons having 10 or less carbon atoms (CC) in the base oil for the metalworking oil composition of the present embodiment is preferably 20% or more, more preferably 25% or more, further preferably 50% or more, particularly preferably 90% or more.

[0058] By setting the ratio of hydrocarbons having a carbon number of 10 or less (CC) to the above-mentioned preferred value or more, the removability is further improved.

[0059] The carbon number distribution in the base oil for the metalworking oil composition of the present embodiment can be controlled by distillation while precisely adjusting the pressure, temperature, reflux ratio, or the number of plates of the distillation tower when producing the above-mentioned mineral oil, GTL, or CTL.

[0060] [Determination of carbon number distribution]

[0061] The measurement conditions of gas chromatography distillation are as follows.

[0062] Model: GC-2030 manufactured by Shimadzu Corporation

[0063] Column: UA-1MS / HT (30m×0.25mml.D.×0.10μm)

[0064] Carrier gas: Helium 200kPa

[0065] Detector: FID

[0066] Detector temperature: 350°C

[0067] Heating box temperature: 50℃ (2 minutes) ~ 170℃

[0068] Temperature change rate: 6℃ / minute

[0069] Injection volume: 1 μL toluene solution

[0070] The initial boiling point of the base oil for the metalworking oil composition of the present embodiment is preferably 120°C or higher, more preferably 130°C or higher, and even more preferably 150°C or higher.

[0071] The final boiling point of the base oil for the metalworking oil composition of the present embodiment is preferably 220°C or lower, more preferably 200°C or lower, and even more preferably 190°C or lower.

[0072] In this specification, the initial boiling point and the final boiling point of the base oil for a metalworking oil composition refer to the values ​​measured by the normal pressure method specified in JIS K2254:2018.

[0073] By setting the initial boiling point of the base oil for the metalworking oil composition of the present embodiment to the above-mentioned preferred value or more, volatilization at room temperature can be more sufficiently prevented, and the processability can be further improved.

[0074] By setting the final boiling point of the base oil for the metalworking oil composition of the present embodiment to be equal to or lower than the above-mentioned preferred value, the removability is further improved.

[0075] The difference between the final boiling point and the initial boiling point (final boiling point - initial boiling point) of the base oil for the metalworking oil composition of the present embodiment is preferably 10° C. or more, more preferably 15° C. or more, and even more preferably 20° C. or more.

[0076] When the difference between the final boiling point and the initial boiling point of the base oil for the metalworking oil composition of the present embodiment is equal to or greater than the above-mentioned preferred value, that is, when the number of hydrocarbons with different carbon numbers increases, the processability is further improved.

[0077] The flash point of the base oil for the metalworking oil composition of one embodiment is less than 70°C, preferably 65°C or less, and more preferably 60°C or less.

[0078] Will pass 1 The proton ratio of the methyl group when the integral value of all protons detected by H-NMR analysis is 100 is 65 or less, preferably 60 or less, more preferably 45 or less, and further preferably 35 or less.

[0079] Will pass 1 The proton ratio of the methyl group when the integral value of all protons detected by H-NMR analysis is 100 is 20 or more, preferably 25 or more, and more preferably 30 or more.

[0080] In the carbon number distribution obtained by gas chromatography distillation, the ratio (CB / CA) of the proportion of hydrocarbons with the largest carbon number (CA) to the proportion of hydrocarbons with the second largest carbon number (CB) is preferably 0.5 or less, more preferably 0.3 or less, further preferably 0.2 or less, and particularly preferably 0.1 or less.

[0081] A mixture of hydrocarbons having 6 to 20 carbon atoms is preferred, and a mixture of hydrocarbons having 6 to 18 carbon atoms is more preferred.

[0082] In addition, from the viewpoint of further improving the processability, the initial boiling point of the base oil for the metalworking oil composition is preferably 120° C. or higher, more preferably 130° C. or higher, and even more preferably 150° C. or higher.

[0083] The final boiling point is preferably 220°C or lower, more preferably 200°C or lower, and further preferably 190°C or lower.

[0084] The difference between the final boiling point and the initial boiling point (final boiling point - initial boiling point) is preferably 10° C. or more, more preferably 15° C. or more, and even more preferably 20° C. or more.

[0085] The base oil for metalworking oil composition of the present embodiment is a base oil suitable for use as a base oil of the metalworking oil composition described later. It is also possible to use the base oil for metalworking oil composition of the present embodiment alone for metalworking. As processing methods, cold rolling, warm rolling, or hot rolling, pressing, punching, thinning and drawing, deep drawing, drawing, forging, metal processing such as cutting and grinding including extremely micro-cutting (MQL) can be listed. As the metal, in addition to aluminum, magnesium and their alloys, transition metals such as copper, iron, chromium, nickel, zinc, tin, titanium and their alloys, electromagnetic steel, or stainless steel can also be listed.

[0086] The kinematic viscosity of the base oil for the metalworking oil composition of the present embodiment at 40° C. is preferably 5 mm 2 / s or less, more preferably 3mm 2 / s or less, further 2mm 2 / s or less.

[0087] The kinematic viscosity in the present invention is a value measured in accordance with JIS K2283:2000.

[0088] (Metalworking oil composition)

[0089] The metalworking oil composition of the present embodiment is a metalworking oil composition containing the above-mentioned base oil for a metalworking oil composition and an optional component.

[0090] Examples of the optional components include base oils other than the above-mentioned base oils for metalworking oil compositions, oiliness agents, antioxidants, rust inhibitors, corrosion inhibitors, rust preventives, defoaming agents, metal cleaning agents, anti-wear agents, viscosity index improvers, pour point depressants, anti-fogging agents, and demulsifiers.

[0091] Base Oil

[0092] Specific examples of the base oil other than the above-mentioned base oil for metalworking oil composition include synthetic oils and mineral oils that do not conform to the above-mentioned base oil for metalworking oil composition.

[0093] Examples of the synthetic oil include polyolefins such as poly-α-olefins, ester base oils such as diesters and polyol esters, polyalkylene glycols, alkylbenzenes, and alkylnaphthalenes.

[0094] The content of the base oil for a metalworking oil composition in the metalworking oil composition of the present embodiment is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 98% by mass or more, and particularly preferably 100% by mass, relative to 100% by mass of the total amount of the base oil contained in the metalworking oil composition.

[0095] That is, in the metalworking oil composition of one embodiment, the upper limit of the content of the base oil other than the base oil for the metalworking oil composition described above is preferably 10 mass % or less, more preferably 5 mass % or less, and further preferably 2 mass % or less.

[0096] Oily Agent

[0097] Examples of the oiliness agent include esters and alcohols.

[0098] Specific examples of the ester include esters having 7 to 26 carbon atoms obtained from a monohydric alcohol and a monobasic acid.

[0099] Specific examples of the alcohol include monohydric alcohols.

[0100] When the metalworking oil composition contains an oiliness agent, the content thereof is, for example, 0.5 to 10% by mass relative to the total amount of the metalworking oil composition. The oiliness agent may be used alone or in combination of two or more.

[0101] Antioxidants

[0102] Examples of antioxidants include phenolic compounds such as 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-p-cresol; amine compounds such as diphenylamine, dialkyldiphenylamine, phenyl-α-naphthylamine, and p-alkylphenyl-α-naphthylamine. When the metalworking oil composition contains an antioxidant, the content thereof is, for example, 0.5 to 10% by mass relative to the total amount of the metalworking oil composition. The antioxidant may be used alone or in combination of a plurality of antioxidants.

[0103] 《Corrosion inhibitor》

[0104] As the anticorrosive agent, for example, known anticorrosive agents such as benzotriazole compounds, tolyltriazole compounds, thiadiazole compounds, and imidazole compounds can be used. When the metalworking oil composition contains an anticorrosive agent, its content is, for example, 0.01 to 10% by mass relative to the total amount of the metalworking oil composition. The anticorrosive agent can be used alone or in combination of multiple anticorrosive agents.

[0105] Rust Inhibitor

[0106] Specific examples of the rust inhibitor include salts of fatty acids such as oleic acid, sulfonates such as dinonylnaphthalenesulfonate, partial esters of polyols such as sorbitan monooleate (excluding partial esters of polyols that correspond to the oiliness agent), amines and their derivatives.

[0107] 《Defoaming agent》

[0108] Examples of the defoaming agent include silicone-based defoaming agents.

[0109] Metal cleaning agent

[0110] As metal-based cleaning agents, for example, normal salts or basic salts such as sulfonates, phenates, and salicylates of alkali metals or alkaline earth metals can be cited. From the viewpoint of suppressing the evaporation of lower fatty acids by neutralizing lower fatty acids, metal-based cleaning agents are preferably basic salts such as sulfonates, phenates, and salicylates of alkali metals or alkaline earth metals. As alkali metals, preferably sodium, potassium, etc. can be cited. As alkaline earth metals, preferably magnesium, calcium, barium, etc. can be cited. Among these metals, magnesium or calcium is preferred, and calcium is more preferred.

[0111] 《Anti-wear agent》

[0112] Examples of the anti-wear agent include dithiocarbamates, zinc dithiocarbamates, molybdenum dithiocarbamates, disulfides, polysulfides, sulfided olefins, and sulfided oils and fats.

[0113] 《Viscosity Index Improver》

[0114] Examples of the viscosity index improver include non-dispersed or dispersed poly(meth)acrylate viscosity index improvers, non-dispersed or dispersed olefin-(meth)acrylate copolymer viscosity index improvers, styrene-maleic anhydride ester copolymer viscosity index improvers, and mixtures thereof.

[0115] 《Flow point depressant》

[0116] Examples of the pour point depressant include polymethacrylate-based polymers and the like.

[0117] Anti-fog agent

[0118] Examples of the anti-fogging agent include ethylene-propylene copolymers, polymethacrylates, polyisobutylene, polybutene, etc. The average molecular weight of these compounds as the anti-fogging agent is usually 10,000 to 8,000,000.

[0119] Demulsifier

[0120] Examples of demulsifiers include polyalkylene glycol-based nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and polyoxyethylene alkylnaphthyl ether.

[0121] The metalworking oil composition of the present embodiment is preferably used in metalworking. Processing methods include cold rolling, warm rolling or hot rolling, pressing, punching, ironing, deep drawing, drawing, forging, cutting including very small amount cutting (MQL), and grinding. As the metal, in addition to aluminum, magnesium, and their alloys, transition metals such as copper, iron, chromium, nickel, zinc, tin, and titanium, and their alloys, electromagnetic steel, or stainless steel, etc. can also be listed.

[0122] The metalworking oil composition of the present embodiment is excellent in processability and removability and is therefore the most suitable composition for press working of aluminum, aluminum alloys, and electromagnetic steel in particular.

[0123] Example

[0124] The present invention will be described in further detail below using examples, but the present invention is not limited to these examples.

[0125] <Preparation of base oil for metalworking oil composition>

[0126] Base oils 1 and 2 having the physical properties shown in Table 1 were prepared.

[0127] [Measurement of proton ratio of methyl group]

[0128] For base oils 1 and 2 1 The proton ratios of the methyl group (CH 3 ), the methylene group (CH 2 ), and the methine group (CH ) were measured when the integrated value of all protons detected by H-NMR analysis was 100. The results are shown in Table 1.

[0129] 1 The measuring apparatus and measuring conditions for H-NMR measurement are as follows.

[0130] Equipment used: AVANCEⅢHD-cryo 600 NMR manufactured by Bruker

[0131] 1 H resonance frequency: 600.18MHz

[0132] Solvent: CDCl3

[0133] Concentration: about 50mg / mL

[0134] Determination method: 1 H non-decoupling method

[0135] Pulse width: 30° pulse

[0136] Waiting time: 5 seconds

[0137] Chemical shift standard: CHCl3 in CDCl3 (7.28 ppm)

[0138] [Determination of distillation properties]

[0139] The initial boiling point and final boiling point of base oils 1 and 2 were measured according to the normal pressure method of JIS K 2254. Table 1 shows the initial boiling point (IBP), final boiling point (FBP), and the difference between the final boiling point and the initial boiling point (FBP-IBP) of base oils 1 and 2.

[0140] [Determination of carbon number distribution]

[0141] The carbon number distribution of base oils 1 and 2 was determined by gas chromatographic distillation.

[0142] The measurement conditions of gas chromatography distillation are as follows.

[0143] Model: GC-2030 manufactured by Shimadzu Corporation

[0144] Column: UA-1MS / HT (30m×0.25mm ID×0.10μm) Carrier gas: Helium 200kP a

[0145] Detector: FID

[0146] Detector temperature: 350°C

[0147] Heating box temperature: 50℃ (2 minutes) ~ 170℃

[0148] Temperature rate: 6℃ / min

[0149] Injection volume: 1 μL toluene solution

[0150] Table 1

[0151]

[0152] <Preparation of Metalworking Oil Composition>

[0153] (Example 1, Comparative Example 1)

[0154] The components shown in Table 2 were mixed to prepare metalworking oil compositions of respective examples.

[0155] [Evaluation of performance excluded]

[0156] A test dish was placed on the mass meter, and 0.5 g of the metalworking oil composition of each example was evenly applied on the test dish. The applied metalworking oil composition of each example was heated at 130° C., and the time required for the mass of the metalworking oil composition of each example to become 0 g was calculated. The results are shown in Table 2. The shorter the time required for the mass of the metalworking oil composition to become 0 g, the better the removability.

[0157] [Evaluation of processing performance]

[0158] A flat plate sliding test of aluminum was carried out to evaluate the processability of the metalworking oil composition of each example.

[0159] Figure 1 This is an explanatory diagram schematically showing a flat plate sliding test. Figure 1 In the test, the test piece 1 is made of aluminum alloy and is dipped and coated in the metalworking oil composition of each example for testing. The test piece 1 is clamped by a pair of flat blocks 2a and 2b, and further from the upper surface side ( Figure 1 Then, the test piece 1 to which the tightening load is applied is moved in the horizontal direction ( Figure 1 The pull-out load when the test piece 1 was pulled out was measured, and the results are shown in Table 2. The smaller the pull-out load when the test piece 1 was pulled out, the better the processability of the metalworking oil composition.

[0160] The details of the test conditions are as follows.

[0161] <Test conditions>

[0162] Aluminum test piece: JIS A1050 material

[0163] Flat plate 2a, 2b: SKD-11, 300mm (width) × 600mm (length) × 10mm (thickness), contact area with test piece 1: 10mm × 250mm

[0164] Fastening load: 1.5kN

[0165] Pulling speed: 100mm / min

[0166] Temperature of the metalworking oil composition of each example during immersion coating: 40°C ± 3°C

[0167] Temperature of test piece 1 during the test: 25°C ± 3°C

[0168] Temperature of flat plate: 25℃±3℃

[0169] Table 2

[0170]

[0171] As shown in Table 2, it was confirmed that the metalworking oil composition of Example 1 had a shorter drying time and a smaller maximum pull-out load than the metalworking oil composition of Comparative Example 1, and therefore had better removal performance and processing performance.

[0172] The preferred embodiments of the present invention are described above, but the present invention is not limited to these embodiments. Additions, omissions, substitutions and other changes in the structure can be made without departing from the scope of the present invention. The present invention is not limited by the above description, but only by the scope of the appended claims.

[0173] Explanation of symbols

[0174] 1: test piece, 2a, 2b: flat plate.

Claims

1. A base oil for a metalworking oil composition, which has a flash point of less than 70°C and will pass 1 A hydrocarbon having a proton ratio of the methyl group of 20 or more and 65 or less when the integrated value of all protons detected by H-NMR analysis is set to 100.

2. The base oil for a metalworking oil composition according to claim 1, wherein In the carbon number distribution obtained by gas chromatograph distillation, the ratio CB / CA of the proportion CA of hydrocarbons with the largest carbon number to the proportion CB of hydrocarbons with the second largest carbon number is 0.5 or less.

3. The base oil for a metalworking oil composition according to claim 1 or 2, wherein In the carbon number distribution obtained by gas chromatography distillation, the ratio CC of hydrocarbons having a carbon number of 10 or less is 20% or more.

4. A metalworking oil composition comprising the base oil for a metalworking oil composition according to claim 1 or 2. 5 . A metalworking oil composition comprising the base oil for a metalworking oil composition according to claim 3 .

6. The metalworking oil composition according to claim 4, wherein The metalworking oil composition is used for press working of metal.

7. The metalworking oil composition according to claim 5, wherein The metalworking oil composition is used for press working of metal.

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