Water-soluble metalworking oil, metalworking fluid, metalworking method, and method for improving dispersibility of water-soluble metalworking oil

Abstract

To provide, e.g., a metalworking oil with improved dispersibility in water.SOLUTION: The water-soluble metalworking oil contains a fatty acid having 8 to 10 carbon atoms, a fatty acid having 18 or more carbon atoms, an alkaline component, water, and a base oil.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a water-soluble metalworking oil, a metalworking fluid, a metalworking method, and a method for improving the dispersibility of a water-soluble metalworking oil.

Background Art

[0002] In the field of metalworking such as cutting and grinding, water-soluble metalworking oils are used. The water-soluble metalworking oil is often used as a metalworking fluid (diluted solution) by diluting the stock solution of the metalworking oil with water. Techniques for improving the dispersibility of such a metalworking oil stock solution in water have been proposed.

[0003] For example, Patent Document 1 discloses a water-soluble metalworking oil composition that reduces tool friction and lengthens tool life by blending a polymer of a hydroxy unsaturated fatty acid and a tertiary amine in a relatively high blending amount, and improves dispersibility in water to improve handleability.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the water-soluble metalworking oil composition described in Patent Document 1 has room for improvement from the viewpoint of dispersibility. A decrease in dispersibility in water causes deterioration of handleability when diluting the stock solution with water, and equipment fouling due to adhesion of emulsification defects in the apparatus in which the metalworking oil is used.

[0006] The main object of the present disclosure is to provide a metalworking oil having improved dispersibility in water.

Means for Solving the Problems

[0007] Aspects of the present disclosure for solving the above problems are as follows.

[0008] [1] A water-soluble metalworking oil containing a fatty acid having 8 to 10 carbon atoms, a fatty acid having 18 or more carbon atoms, an alkali component, water, and a base oil. [2] The water-soluble metalworking oil according to [1], wherein the difference in the number of carbon atoms between the fatty acid having 18 or more carbon atoms and the fatty acid having 8 to 10 carbon atoms is 8 or more. [3] The water-soluble metalworking oil according to [1] or [2], wherein the fatty acid having 8 to 10 carbon atoms contains a branched fatty acid. [4] The water-soluble metalworking oil according to any one of [1] to [3], wherein the content of the fatty acid having 8 to 10 carbon atoms is 0.1% by mass or more and 15% by mass or less. [5] The water-soluble metalworking oil according to any one of [1] to [4], wherein the mass ratio of the content of the fatty acid having 8 to 10 carbon atoms to the content of the fatty acid having 18 or more carbon atoms (fatty acid having 8 to 10 carbon atoms / fatty acid having 18 or more carbon atoms) is 0.050 or more and 10.0 or less. [6] The water-soluble metalworking oil according to any one of [1] to [5], wherein the alkali component is at least one selected from the group consisting of an inorganic alkali and an organic amine. [7] The water-soluble metalworking oil according to any one of [1] to [6], wherein the fatty acid having 18 or more carbon atoms is oleic acid. [8] A metalworking fluid obtained by diluting the water-soluble metalworking oil according to any one of [1] to [7] with water. [9] A metalworking method of processing a workpiece made of metal using a metalworking fluid obtained by diluting the water-soluble metalworking oil according to any one of [1] to [7] with water.

[10] A method for improving the dispersibility of a water-soluble metalworking oil, including a step of mixing a fatty acid having 8 to 10 carbon atoms, an alkali component, a fatty acid having 18 or more carbon atoms, water, and a base oil.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a metalworking oil having improved dispersibility in water and the like.

Brief Description of the Drawings

[0010]

Figure 1

Modes for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. The elements listed below can be arbitrarily combined, and the scope of the present invention is intended to include all changes within the scope of the claims and the scope equivalent to the claims. In addition, in this specification, the upper limit value and the lower limit value exemplified for a numerical range can be arbitrarily combined to form a new numerical range. For example, when "A or more and B or less" and "C or more and D or less" are described, the ranges of "A or more and D or less" and "C or more and B or less" may also be included in the numerical range.

[0012] In this specification, when defining the number of carbon atoms of a certain group, this number of carbon atoms means the number of carbon atoms of the entire group unless otherwise specified. That is, when this group has a substituent, it means the total number of carbon atoms including this substituent.

[0013] [Metalworking Fluid] The metalworking fluid of this embodiment contains a fatty acid having 8 to 10 carbon atoms, a fatty acid having 18 or more carbon atoms, an alkali component, water, and a base oil. Hereinafter, in order to distinguish between the fatty acid having 8 to 10 carbon atoms and the fatty acid having 18 or more carbon atoms, the fatty acid having 8 to 10 carbon atoms is also described as a short-chain fatty acid, and the fatty acid having 18 or more carbon atoms is also described as a long-chain fatty acid.

[0014] When the metalworking fluid is made into a metalworking liquid (diluted liquid) by using the metalworking fluid as a stock solution and diluting it with water, the dispersibility of the stock solution with respect to water can be improved, and the generation of aggregates (suspended matters) can be suppressed. In this specification, the dispersibility with respect to water means the property that the particles in the metalworking fluid are dispersed in water without aggregating.

[0015] The metalworking fluid of this embodiment contains short-chain fatty acids together with long-chain fatty acids to improve water dispersibility. The short-chain fatty acids function as dispersants. Although the mechanism by which the metalworking fluid of the present disclosure is excellent in water dispersibility is not clear, it is presumed as follows.

[0016] It is considered that the undiluted oil agent containing water, base oil, and surfactant has a lamellar structure in which water and base oil are microscopically mixed and overlapped in layers and has fluidity. Long-chain fatty acids that function as surfactants are adsorbed on the water-oil interface. The long-chain fatty acids are aligned with the hydrophilic part in the water layer direction and the lipophilic part in the oil layer direction. As an emulsification process during water dilution of the undiluted oil agent, shear force acting on the dilution liquid causes fluctuations at the water-oil interface, and the oil components gradually become rounded at the oil interface, and are divided from the constricted parts to form oil droplets, generating an O / W emulsion. The long-chain fatty acids adsorbed on the water-oil interface interact intermolecularly between adjacent molecules. The stronger the interaction acting between molecules, the stronger the action as the resistance to deformation of the water-oil interface, and the more difficult it is to form an O / W emulsion. Therefore, it is presumed that by weakening the intermolecular interaction, the formation of the O / W emulsion becomes easier, and the dispersibility and dilution property of the undiluted oil agent can be enhanced.

[0017] The short-chain fatty acids undergo a neutralization reaction with the alkaline component and are adsorbed on the water-oil interface. By adsorbing on the water-oil interface so that the short-chain fatty acids with a small number of carbon atoms and a short chain length enter between adjacent long-chain fatty acid molecules, compared with the case where only long-chain fatty acids are adsorbed on the water-oil interface, the intermolecular distance between adjacent long-chain fatty acids is widened. Since there is a difference in the number of carbon atoms (difference in chain length) between the short-chain fatty acids and the long-chain fatty acids, the interaction acting on the hydrocarbon corresponding to this difference is weakened. The formation of oil droplets becomes easier because the weakened interaction part becomes a starting point and is easily divided. As a result, it is presumed that the dispersibility of the undiluted oil agent is improved and it becomes easier to be emulsified.

[0018] The water-soluble metalworking fluid of the embodiment contains fatty acids having 8 to 10 carbon atoms. A fatty acid is a monovalent carboxylic acid of hydrocarbon and is a compound represented by the general formula CnHmCOOH. The fatty acids having 8 to 10 carbon atoms may be linear or branched, preferably branched. The fatty acids having 8 to 10 carbon atoms may be either saturated fatty acids or unsaturated fatty acids, preferably saturated fatty acids. The fatty acids having 8 to 10 carbon atoms are preferably branched saturated fatty acids.

[0019] From the viewpoint of water dispersibility, the fatty acids having 8 to 10 carbon atoms preferably have 8 or 9 carbon atoms, more preferably 8 carbon atoms.

[0020] Examples of the fatty acids having 8 to 10 carbon atoms include octanoic acid, nonanoic acid, decanoic acid, ethylhexanoic acid, isononanoic acid, isodecanoic acid, neodecanoic acid, etc., preferably ethylhexanoic acid, isononanoic acid, neodecanoic acid. The fatty acids having 8 to 10 carbon atoms may be used alone or in combination of two or more.

[0021] From the viewpoint of water dispersibility, the HLB of the fatty acids having 8 to 10 carbon atoms is preferably 5.2 or more, more preferably 5.7 or more.

[0022] In this specification, HLB is an abbreviation of Hydrophile-lipophile balance (hydrophilic-lipophilic balance) and is an index indicating the balance between hydrophilic groups and lipophilic groups in the molecule of a compound. In this specification, HLB is a value defined by the following calculation formula by the Griffin method. HLB value = 20 × [sum of chemical formula weights of hydrophilic parts] / molecular weight For example, in the case of octanoic acid (C 7 H 15 COOH; linear saturated fatty acid having 8 carbon atoms), the molecular weight = 144, and the chemical formula weight of the hydrophilic part = 45 (carboxy group (-COOH)), so the HLB value is 6.25.

[0023] Fatty acids having 8 to 10 carbon atoms are preferably 0.1% by mass or more and 15% by mass or less, more preferably 0.4% by mass or more and 13% by mass or less, still more preferably 0.8% by mass or more and 12% by mass or less, even more preferably 1.5% by mass or more and 11% by mass or less, and even more preferably 3.5% by mass or more and 10% by mass or less from the viewpoints of water dispersibility and obtaining effects commensurate with use in a water-soluble metalworking fluid. When two or more are used in combination, the content means the total amount.

[0024] The water-soluble metalworking fluid of the embodiment contains a fatty acid having 18 or more carbon atoms. The fatty acid having 18 or more carbon atoms contributes to the improvement of water dispersion performance due to coexistence with the fatty acid having 8 to 10 carbon atoms and has a function of improving the liquid stability of the metalworking fluid and its dilution.

[0025] The fatty acid having 18 or more carbon atoms may be linear or branched, and is preferably linear. Also, the fatty acid having 18 or more carbon atoms may be either a saturated fatty acid or an unsaturated fatty acid, and is preferably a linear unsaturated fatty acid.

[0026] The upper limit of the number of carbon atoms of the fatty acid having 18 or more carbon atoms is not particularly limited, but is usually 72. The fatty acid having 18 or more carbon atoms may be a polymer having a saturated fatty acid or an unsaturated fatty acid having 18 or more carbon atoms as a monomer. The fatty acid having 18 or more carbon atoms is preferably 18 in terms of the synergistic effect with the fatty acid having 8 to 10 carbon atoms and the ease of availability.

[0027] Examples of the fatty acid having 18 or more carbon atoms include stearic acid, oleic acid, linoleic acid, linolenic acid, ricinoleic acid, castor oil fatty acid condensate, etc., and oleic acid is preferred. The fatty acid having 18 or more carbon atoms may be used alone or in combination of two or more.

[0028] The difference in the number of carbon atoms between the fatty acid having 8 to 10 carbon atoms and the fatty acid having 18 or more carbon atoms is preferably 8 or more, more preferably 9 or more, and still more preferably 10 or more from the viewpoint of water dispersion performance.

[0029] Fatty acids having 18 or more carbon atoms are preferably 1% by mass or more and 30% by mass or less, more preferably 2% by mass or more and 20% by mass or less, still more preferably 3% by mass or more and 10% by mass or less, even more preferably 4% by mass or more and 8% by mass or less, and even more preferably 4% by mass or more and 6% by mass or less from the viewpoints of liquid stability and water dispersibility in the water-soluble metalworking fluid. When two or more kinds are used in combination, the content means the total amount.

[0030] In the water-soluble metalworking fluid of the embodiment, the mass ratio of the content of fatty acids having 8 to 10 carbon atoms to the content of fatty acids having 18 or more carbon atoms (fatty acids having 8 to 10 carbon atoms / fatty acids having 18 or more carbon atoms) is preferably 0.05 or more and 10.0 or less, more preferably 0.10 or more and 5.0 or less, still more preferably 0.15 or more and 4.0 or less, even more preferably 0.35 or more and 3.0 or less, and even more preferably 0.80 or more and 2.5 or less from the viewpoint of water dispersibility.

[0031] The water-soluble metalworking fluid of the embodiment contains an alkali component. By neutralizing the fatty acid with the alkali component, the hydrophilicity of the fatty acid can be improved. Examples of the alkali component include organic amines and inorganic alkalis, and organic amines are preferred.

[0032] Examples of the organic amine include alkanolamines. Specifically, primary alkanolamines (monoethanolamine, monoisopropanolamine, 2-amino-2-methyl-1-propanol, diglycolamine, etc.), secondary alkanolamines (diethanolamine, diisopropanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, etc.), tertiary alkanolamines (triethanolamine, triisopropanolamine, diethanolmonoisopropanolamine, monoethanoldiisopropanolamine, N-cyclohexyldiethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, etc.) and the like can be mentioned, and tertiary alkanolamines are preferred. Examples of the inorganic alkali include potassium hydroxide and sodium hydroxide.

[0033] From the perspective of neutralization stability, the content of the alkali component in the water-soluble metalworking fluid is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.8% by mass or more and 10% by mass or less, still more preferably 0.5% by mass or more and 5% by mass or less, and even more preferably 1% by mass or more and 3% by mass or less. When two or more are used in combination, the content means the total amount.

[0034] In the water-soluble metalworking fluid of the embodiment, the mass ratio of the content of the fatty acid having 8 to 10 carbon atoms to the content of the alkali component (fatty acid having 8 to 10 carbon atoms / alkali component) is preferably 0.1 or more and 15.0 or less, more preferably 0.5 or more and 10.0 or less, still more preferably 1.0 or more and 8.0 or less, and even more preferably 2.5 or more and 7.0 or less from the perspective of water dispersibility.

[0035] The water-soluble metalworking fluid of the embodiment contains water. Examples of the water include tap water, industrial water, ion-exchanged water, distilled water, sterilized purified water, etc., and hard water or soft water may be used. The water may be used alone or in combination of two or more.

[0036] From the perspectives of processability and water dispersibility, the content of water in the water-soluble metalworking fluid is preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 10% by mass or less, still more preferably 3% by mass or more and 8% by mass or less, and even more preferably 5% by mass or more and 7% by mass or less. When two or more are used in combination, the content means the total amount.

[0037] In the water-soluble metalworking fluid of the embodiment, the mass ratio of the content of the fatty acid having 8 to 10 carbon atoms to the content of water (fatty acid having 8 to 10 carbon atoms / water) is preferably 0.05 or more and 5.0 or less, more preferably 0.1 or more and 3.0 or less, still more preferably 0.2 or more and 2.0 or less, and even more preferably 0.5 or more and 1.5 or less from the perspective of water dispersibility.

[0038] The water-soluble metalworking oil agent of the embodiment contains a base oil. Examples of the base oil include mineral oil, synthetic oil, animal and vegetable oils and fats, etc., preferably mineral oil and synthetic oil. Examples of the mineral oil include spindle oil, machine oil, cylinder oil, paraffin oil, gear oil, etc., preferably paraffin oil. Examples of the synthetic oil include synthetic oils such as hydrocarbon-based synthetic oil, ester-based synthetic oil, ether-based synthetic oil, etc., preferably ester-based synthetic oil. Examples of the ester-based synthetic oil include esters of carboxylic acids (for example, having 10 to 30 carbon atoms, preferably 12 to 28 carbon atoms, more preferably 15 to 25 carbon atoms) and alcohols (for example, having 1 to 30 carbon atoms, preferably 1 to 25 carbon atoms, more preferably 1 to 20 carbon atoms). The above alcohol may be any of primary, secondary and tertiary alcohols, and may also be any of monoalcohol, dialcohol, trialcohol and tetraalcohol. Examples of the ester-based synthetic oil include methyl oleate, 2-ethylhexyl oleate, neopentyl glycol dioleate, trimethylolpropane trioleate, pentaerythritol tetraoleate, etc., preferably 2-ethylhexyl oleate. Examples of the animal and vegetable oils and fats include animal oils and fats (such as lard, beef tallow, fish oil, etc.), vegetable oils and fats (such as rapeseed oil, soybean oil, palm oil, etc.), hydrogenated products thereof, etc. The base oil may be used alone or in combination of two or more.

[0039] From the viewpoints of processability and water dispersibility, the content of the base oil in the water-soluble metalworking oil agent is preferably 0.1% by mass or more and 80% by mass or less, more preferably 5% by mass or more and 75% by mass or less, still more preferably 10% by mass or more and 70% by mass or less, even more preferably 30% by mass or more and 67% by mass or less, and even more preferably 50% by mass or more and 65% by mass or less. When two or more are used in combination, the content means the total amount.

[0040] In the water-soluble metalworking fluid of the embodiment, the mass ratio of the content of fatty acids having 8 to 10 carbon atoms to the content of the base oil (fatty acids having 8 to 10 carbon atoms / base oil) is preferably 0.005 or more and 1.0 or less, more preferably 0.01 or more and 0.5 or less, still more preferably 0.03 or more and 0.3 or less, and even more preferably 0.06 or more and 0.2 or less from the viewpoint of water dispersibility.

[0041] In addition to the above essential components, the water-soluble metalworking fluid of the embodiment can contain various additives, etc. as necessary within a range that does not interfere with the effects of the present invention. Examples of the additives include surfactants, metal corrosion inhibitors, preservatives, alcohols, glycols, antifoaming agents, etc.

[0042] Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, etc. From the viewpoints of stock solution stability and diluted solution stability, nonionic surfactants and anionic surfactants are preferred.

[0043] Examples of the nonionic surfactant include ethers, esters, amines, amides, etc. Examples of the ethers include alkyl ethers, polyoxyalkylene ethers, polyoxyalkylene alkyl ethers, etc., and polyoxyalkylene alkyl ethers are preferred. Examples of the esters include glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxysorbitol fatty acid esters, etc., and sorbitan fatty acid esters are preferred. Examples of the amines include polyoxyalkylene alkylamines, EO adducts of organic amines, etc., and EO adducts of organic amines (for example, 1 to 20 moles) are preferred. Examples of the amides include coconut oil fatty acid diethanolamide, oleic acid diethanolamide, etc. Preferred nonionic surfactants are polyoxyalkylene lauryl ether, sorbitan monooleate, and EO adduct of laurylamine.

[0044] Examples of the anionic surfactant include polyoxyalkylene alkyl ether phosphate, alkylbenzene sulfonic acid, α-olefin sulfonic acid, salts thereof, etc., and preferably an alkylbenzene sulfonate. The anionic surfactant is preferably sodium sulfonate.

[0045] Examples of the cationic surfactant include quaternary ammonium salts (such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, etc.). Examples of the amphoteric surfactant include alkyl betaine as a betaine type. The surfactant may be used alone or in combination of two or more.

[0046] From the viewpoints of the stock solution stability and the diluted solution stability in the water-soluble metal working oil, the content of the surfactant is, for example, 0.1% by mass or more and 40% by mass or less, preferably 1% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less. When two or more are used in combination, the content means the total amount.

[0047] Examples of the metal corrosion inhibitor include phosphate esters, alkylphosphonic acids, sodium metasilicate, benzotriazole, etc., and preferably benzotriazole. The metal corrosion inhibitor may be used alone or in combination of two or more. From the water-soluble metal working oil, the content of the metal corrosion inhibitor is, for example, 0.01% by mass or more and 5% by mass or less, preferably 0.05% by mass and 3% by mass or less. When two or more are used in combination, the content means the total amount.

[0048] Examples of the preservative include organic amines. Examples of the organic amines include cyclohexylamine, dicyclohexylamine, N-methyldicyclohexylamine, N,N-dimethyldicyclohexylamine, dibenzylamine, 1,3-bis(aminomethyl)cyclohexane, etc., and dicyclohexylamine is preferred. The preservative may be used alone or in combination of two or more. The content of the preservative in the water-soluble metalworking oil is, for example, 0.1% by mass or more and 15% by mass or less, preferably 0.5% by mass and 12% by mass or less. The content in the case of using two or more in combination means the total amount.

[0049] Examples of the alcohols include benzyl alcohol, phenoxyethanol, phenoxypropanol, decanol, dodecanol, tetradecanol, palmityl alcohol, stearyl alcohol, oleyl alcohol, etc., and benzyl alcohol is preferred. The alcohols may be used alone or in combination of two or more. The content of the alcohols in the water-soluble metalworking oil is, from the viewpoint of the stability of the undiluted solution, for example, 0.1% by mass or more and 10% by mass or less, preferably 1% by mass and 5% by mass or less. The content in the case of using two or more in combination means the total amount.

[0050] Examples of the glycols include diethylene glycol, 1,2-propanediol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol monohexyl ether, hexylene glycol, diethylene glycol mono-2-ethylhexyl ether, etc., and diethylene glycol mono-2-ethylhexyl ether is preferred. The glycols may be used alone or in combination of two or more. The content of the glycols in the water-soluble metalworking oil is, from the viewpoint of the stability of the undiluted solution, for example, 0.1% by mass or more and 10% by mass or less, preferably 0.5% by mass and 5% by mass or less. The content in the case of using two or more in combination means the total amount.

[0051] Examples of the defoaming agent include silicone-based defoaming agents, higher alcohol-based defoaming agents, polyether-based defoaming agents, and metal soap-based defoaming agents, and preferably silicone-based defoaming agents. The defoaming agent may be used alone or in combination of two or more. The content of the defoaming agent in the water-soluble metalworking fluid is, for example, 0.01% by mass or more and 5% by mass or less, preferably 0.05% by mass to 3% by mass or less. The content in the case of using two or more in combination means the total amount.

[0052] In addition to the above essential components, the water-soluble metalworking fluid of the embodiment can contain fatty acids other than fatty acids having 8 to 10 carbon atoms and fatty acids having 18 or more carbon atoms from the viewpoint of improving lubricity, corrosion resistance, and rust prevention as long as the effects of the present invention are not impaired. Examples of the optional component fatty acid include fatty acids having 7 or less carbon atoms, fatty acids having 11 to 17 carbon atoms, and the like. The optional component fatty acid may be used alone or in combination of two or more. The content of the optional component fatty acid in the water-soluble metalworking fluid is, for example, 3% by mass or less, preferably 1% by mass or less, more preferably 0.1% by mass or less. The content in the case of using two or more in combination means the total amount.

[0053] The water-soluble metalworking fluid of the embodiment is produced by mixing the above components. The addition order and mixing method of each component are not particularly limited. For example, the water-soluble metalworking fluid may be mixed by stirring the above components. The stirring conditions are not particularly limited, but for example, it may be stirred at about 100 rpm for about 5 to 20 minutes at room temperature using a stirrer.

[0054] The water-soluble metalworking fluid of the embodiment may be produced by adding a fatty acid having 8 to 10 carbon atoms to a water-soluble metalworking fluid containing a fatty acid having 18 or more carbon atoms, an alkali component, water, a base oil, etc. described above.

[0055] The water-soluble metalworking fluid of the embodiment can be used as it is for processing a workpiece made of metal, but because it has excellent water dispersibility, it can be particularly preferably used as a stock solution for a metalworking fluid in which the water-soluble metalworking fluid is diluted with dilution water.

[0056] Metalworking fluid The metalworking fluid of the embodiment contains the above-described water-soluble metalworking oil agent and dilution water. Examples of the dilution water include tap water, industrial water, ion-exchanged water, distilled water, sterilized purified water, etc., and it may be hard water or soft water. The dilution water may be used alone or in combination of two or more.

[0057] The dilution ratio when diluting the water-soluble metalworking oil agent with dilution water can be appropriately adjusted according to the composition of the water-soluble metalworking oil agent and the performance required during metalworking. The dilution ratio is not limited, but it is usually preferably diluted and used at 1.5 times or more and 100 times or less. From the viewpoints of water dispersibility and liquid stability, the dilution ratio is more preferably 5 times or more and 50 times or less, and even more preferably 10 times or more and 30 times or less.

[0058] From the viewpoint of corrosion inhibition, the pH of the metalworking fluid is preferably 6.5 or more and 11.0 or less, and more preferably 7.0 or more and 11.0 or less.

[0059] The metalworking fluid of the embodiment is obtained by diluting the water-soluble metalworking oil agent with dilution water. The dilution method of the water-soluble metalworking oil agent is not particularly limited, and it may be diluted by a known method. For example, it may be mixed by stirring using a rotor or a propeller or manually, or the water-soluble metalworking oil agent may be put into a container containing dilution water and diluted by stirring by natural convection.

[0060] The metalworking fluid according to the embodiment is excellent in dispersibility and workability, and can suppress the generation of stickiness in the apparatus in which the metalworking fluid is used. Therefore, it can be suitably used for various metalworkings such as cutting, grinding, polishing, cutting, forging, pressing, rolling, wire drawing, drawing, and ironing of a workpiece made of metal. Examples of the workpiece include ferrous metals and their alloys, non-ferrous metals such as stainless steel, aluminum, aluminum alloys, magnesium, magnesium alloys, copper, copper alloys, and their alloys.

[0061] [Metalworking method] The metal processing method according to the embodiment processes a workpiece made of metal using the above-described metal working fluid. Examples of the processing of the workpiece include cutting, grinding, polishing, cutting, forging, pressing, rolling, wire drawing, drawing, and ironing. The metal working fluid is supplied to the processing point in a liquid state or a mist state, for example. Examples of the workpiece include the above-described metals.

[0062] [Method for improving dispersibility of water-soluble metalworking oil] The method for improving the dispersibility of the water-soluble metalworking oil according to the embodiment includes a step of mixing the above-described fatty acid having 8 to 10 carbon atoms, fatty acid having 18 or more carbon atoms, alkali component, water, and base oil. In the dispersibility improvement method according to the embodiment, since the water-soluble metalworking oil containing a fatty acid having 18 or more carbon atoms, an alkali component, water, and a base oil further contains a fatty acid having 8 to 10 carbon atoms, the dispersibility of the water-soluble metalworking oil in water can be improved.

Examples

[0063] Hereinafter, the present invention will be described more specifically based on examples and comparative examples, but the present invention is not intended to be limited to these examples.

[0064] (Preparation of water-soluble metalworking oil) [Example 1-1] With respect to 100 parts by mass of a blank containing a fatty acid having 18 or more carbon atoms, an alkali component, water, a base oil, and an additive, each component was weighed according to the composition shown in Table 2 so that the content of octanoic acid as a fatty acid having 8 to 10 carbon atoms was 2.0 parts by mass. Using a stir bar (15 mm × 35 mm, football type) and a stirrer (“SLOW STIRRER SW-600N-1” manufactured by Nisshin Rika Co., Ltd.), these were stirred and mixed at 5 graduations for about 15 minutes at room temperature to obtain the water-soluble metalworking oil of Example 1-1. The composition of the blank is as shown in Table 1. In Example 1-1, the pH of the metal working fluid diluted to 5 parts by mass with tap water was 7.0. The pH was measured using a pH meter (“F-52” manufactured by HORIBA, Ltd.).

[0065] [Examples 1-2 to 4-6, Comparative Examples 1-1 to 4-1] The metalworking oil compositions of Examples 1-2 to 4-6 and Comparative Examples 1-1 to 4-1 were prepared in the same manner as in Example 1-1, except that the blending ratios of the respective components in the water-soluble metalworking oil were as shown in Tables 2 to 5. The content of the fatty acid having 8 to 10 carbon atoms was 1.0 part by mass in Examples 2-1 to 2-6, 5.0 parts by mass in Examples 3-1 to 3-6, and 10.0 parts by mass in Examples 4-1 to 4-6 with respect to 100 parts by mass of the above blank. Comparative Example 1-3 corresponds to a blank to which no fatty acid having 8 to 10 carbon atoms and comparative compound are added.

[0066] (Water dispersibility evaluation) Into a flat-bottomed beaker having a capacity of 500 mL, 380.0 g of tap water as dilution water and the above stirrer were respectively placed, and 20.0 g of each water-soluble metalworking oil (undiluted solution) was introduced from a position about 15 cm above the water surface. Thereafter, using the above stirrer, stirring and mixing were carried out for 10 seconds at 3 graduations, and after stopping the stirring, the mixture was allowed to stand for 30 seconds. After standing, the appearance of the diluted solution was visually confirmed and evaluated according to the following criteria. In the cases of A and B, it was determined that the water dispersibility was good. The evaluation results are shown in Tables 2 to 5. (Evaluation criteria) A: No floating matter is seen on the surface of the diluted solution B: A small amount of floating matter is seen on the surface of the diluted solution C: A medium amount of floating matter is seen on the surface of the diluted solution D: A large amount of floating matter is seen on the surface of the diluted solution

[0067] Figure 1 is an image for explaining the evaluation criteria for water dispersibility. Note that Figure 1 is an exemplary image for explaining the evaluation criteria and does not limit the actual evaluation results. The dotted line in the image represents the region of the floating matter.

[0068] Details of the respective components shown in Tables 1 to 5 are as follows. <Fatty acid having 18 or more carbon atoms> Oleic acid (carbon number 18) <Alkali component> N-cyclohexyldiethanolamine <Base oil> Paraffinic mineral oil 2-Ethylhexyl oleate <Additive> Surfactant Nonionic surfactant 1: Laurylamine EO 15 mol adduct Nonionic surfactant 2: Sorbitan monooleate Nonionic surfactant 3: Polyoxyalkylene lauryl ether Anionic surfactant: Sodium sulfonate Metal corrosion inhibitor: Benzotriazole Preservative: Dicyclohexylamine Alcohols: Benzyl alcohol Glycols: "2-Ethylhexyl diglycol" manufactured by Nippon Emulsifier Co., Ltd. Defoamer: Silicone-based defoamer <Fatty acid> Fatty acid A1: Octanoic acid (carbon number 8, straight chain, HLB 6.3) Fatty acid A2: 2-Ethylhexanoic acid (carbon number 8, branched chain, HLB 6.3) Fatty acid A3: Nonanoic acid (carbon number 9, straight chain, HLB 5.7) Fatty acid A4: Isononanoic acid (carbon number 9, branched chain, HLB 5.7) Fatty acid A5: Decanoic acid (carbon number 10, straight chain, HLB 5.2) Fatty acid A6: Neodecanoic acid (carbon number 10, branched chain, HLB 5.2) Fatty acid B1: Polymer of hydroxy unsaturated fatty acid (carbon number 72, branched chain, HLB 0.8) Fatty acid B2: Stearic acid (carbon number 18, straight chain, HLB 3.2) Note that fatty acids A1 to A6 are fatty acids with carbon numbers 8 to 10, and fatty acids B1 to B2 are comparative compounds.

[0069] [Table 1]

[0070] [Table 2]

[0071]

Table 3

[0072]

Table 4

[0073]

Table 5

[0074] As is clear from Tables 2 to 5, it can be seen that in the examples containing fatty acids having 8 to 10 carbon atoms and fatty acids having 18 or more carbon atoms, the dispersibility of the stock solution in water is good. On the other hand, in the comparative examples not containing fatty acids having 8 to 10 carbon atoms, the dispersibility of the stock solution in water was poor.

[0075] From Comparative Examples 1-1 and 1-2, it can be seen that when fatty acids having 11 or more carbon atoms are added instead of fatty acids having 8 to 10 carbon atoms, the water dispersibility is poor. From Examples 1-5 and 1-6, Examples 2-3 and 2-4, etc., it can be seen that among fatty acids having the same number of carbon atoms, branched fatty acids are more excellent in water dispersibility. From each example, it can be seen that as the difference in the number of carbon atoms between fatty acids having 18 or more carbon atoms and fatty acids having 8 to 10 carbon atoms increases, and as the content of fatty acids having 8 to 10 carbon atoms increases, the water dispersibility tends to improve.

[0076] From the above, it was confirmed that the water-soluble metal working oil agent of the present disclosure is excellent in water dispersibility.

Claims

1. A water-soluble metalworking fluid containing a fatty acid having 8 to 10 carbon atoms, a fatty acid having 18 or more carbon atoms, an alkali component, water, and a base oil.

2. The water-soluble metalworking fluid according to claim 1, wherein the difference in the number of carbon atoms between the fatty acid having 18 or more carbon atoms and the fatty acid having 8 to 10 carbon atoms is 8 or more.

3. The water-soluble metalworking fluid according to claim 1 or 2, wherein the fatty acid having 8 to 10 carbon atoms contains a branched fatty acid.

4. The water-soluble metalworking fluid according to claim 1 or 2, wherein the content of the fatty acid having 8 to 10 carbon atoms is 0.1% by mass or more and 15% by mass or less.

5. The water-soluble metalworking fluid according to claim 1 or 2, wherein the mass ratio of the content of the fatty acid having 8 to 10 carbon atoms to the content of the fatty acid having 18 or more carbon atoms (fatty acid having 8 to 10 carbon atoms / fatty acid having 18 or more carbon atoms) is 0.050 or more and 10.0 or less.

6. The water-soluble metalworking fluid according to claim 1 or 2, wherein the alkali component is at least one selected from the group consisting of an inorganic alkali and an organic amine.

7. The water-soluble metalworking fluid according to claim 1 or 2, wherein the fatty acid having 18 or more carbon atoms is oleic acid.

8. A metalworking fluid obtained by diluting the water-soluble metalworking fluid according to claim 1 or 2 with water.

9. A metalworking method of processing a workpiece made of metal using the metalworking fluid obtained by diluting the water-soluble metalworking fluid according to claim 1 or 2 with water.

10. A method for improving the dispersibility of a water-soluble metalworking fluid, comprising a step of mixing a fatty acid having 8 to 10 carbon atoms, a fatty acid having 18 or more carbon atoms, an alkali component, water, and a base oil.

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