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

Abstract

Provided are: a metalworking oil agent having improved dispersibility in water; and the like. The water-soluble metalworking oil contains a fatty acid having 8-10 carbon atoms, a fatty acid having 18 or more carbon atoms, a base component, water, and a base oil.

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 the water-soluble metalworking oil. Background Art

[0002] In the field of metalworking such as cutting and grinding, water-soluble metalworking oils are used. Water-soluble metalworking oils are often prepared by diluting a stock solution of the metalworking oil in water and using it as a metalworking fluid (diluent). A technique for improving the dispersibility of such a stock solution of the metalworking oil in water has been proposed.

[0003] For example, Patent Document 1 discloses a water-soluble metalworking oil composition which contains a hydroxy unsaturated fatty acid polymer and a tertiary amine in relatively high amounts, thereby reducing tool friction and extending tool life, and improving dispersibility in water and improving workability. Prior art literature Patent Literature

[0004] Patent Document 1: International Publication No. 2017 / 073553 Summary of the invention Technical problem 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. Reduced dispersibility in water leads to deterioration of workability when the stock solution is diluted in water and equipment contamination due to adhesion of inadequate emulsification products in equipment using the metalworking oil.

[0006] A main object of the present invention is to provide a metalworking oil having improved dispersibility in water. Technical solutions for solving technical problems

[0007] Means of the present invention for solving the above-mentioned problems are as follows.

[0008] [1] A water-soluble metalworking oil comprising 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 carbon number 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 includes 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] A 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 greater than 0.050 and less than 10.0. [6] The water-soluble metalworking fluid according to any one of [1] to [5], wherein the alkaline component is at least one selected from an inorganic base 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 comprising processing a workpiece containing metal using a metalworking fluid obtained by diluting the water-soluble metalworking fluid according to any one of [1] to [7] with water.

[10] A method for improving the dispersibility of a water-soluble metalworking oil, comprising the 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. Effects of the Invention

[0009] According to the present invention, it is possible to provide a metalworking oil or the like having improved dispersibility in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is an image explaining the evaluation criteria of water dispersibility. DETAILED DESCRIPTION

[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 combined arbitrarily, and the scope of the present invention is intended to include all changes in the claims and the scope equivalent to the claims. In addition, in this specification, the upper limit and lower limit of the numerical range can be arbitrarily combined to form a new numerical range. For example, in the case of "A or more and B or less" and "C or more and D or less", the range of "A or more and D or less" and "C or more and B or less" can also be included in the numerical range.

[0012] In this specification, when the number of carbon atoms in a group is specified, unless otherwise specified, the number of carbon atoms refers to the number of carbon atoms in the entire group. That is, when the group is in a form further having a substituent, it refers to the number of carbon atoms in the entire group including the substituent.

[0013] [Metalworking oil] The metalworking oil of the present 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 a fatty acid having 8 to 10 carbon atoms and a fatty acid having 18 or more carbon atoms, a fatty acid having 8 to 10 carbon atoms is also described as a short-chain fatty acid, and a fatty acid having 18 or more carbon atoms is also described as a long-chain fatty acid.

[0014] A metalworking oil agent, when the metalworking oil agent is used as a stock solution and diluted with water to form a metalworking fluid (diluted solution), can improve the dispersibility of the stock solution in water and inhibit the generation of coagulation (suspended matter). In this specification, the dispersibility in water refers to the property that particles in the metalworking oil agent are dispersed in water without coagulation.

[0015] The metalworking oil of this embodiment contains a long-chain fatty acid and a short-chain fatty acid to improve water dispersibility. The short-chain fatty acid functions as a dispersant. The mechanism of the excellent water dispersibility of the metalworking oil of the present invention is not yet clear, but it is speculated as follows.

[0016] It is believed that the water and base oil in the oil solution containing water, base oil and surfactant are mixed and overlapped in layers, and it is a layered structure with fluidity. Long-chain fatty acids that function as surfactants are adsorbed at the water-oil interface. The long-chain fatty acids are arranged in a manner that the hydrophilic part is arranged in the direction of the water layer and the lipophilic part is arranged in the direction of the oil layer. As the emulsification process of water dilution of the oil solution, the shear force acting on the diluent generates fluctuations at the water-oil interface, and the oil component at the oil interface becomes gradually rounded and is cut off from the part where the neck is generated, thereby forming oil droplets and generating O / W emulsions. The long-chain fatty acids adsorbed at the water-oil interface interact with each other intermolecularly between adjacent molecules. The stronger the interaction between molecules, the stronger the effect as a resistance to deformation of the water-oil interface, and the more difficult it is to form an O / W emulsion. Therefore, it is speculated that by weakening the interaction between molecules, the formation of O / W emulsions becomes easier, and the dispersibility and dilution of the oil solution can be improved.

[0017] Short-chain fatty acids react with the alkali component to neutralize and adsorb to the water-oil interface. Short-chain fatty acids with a small number of carbon atoms and a short chain length are adsorbed to the water-oil interface in a manner that enters between adjacent long-chain fatty acid molecules. As a result, the distance between adjacent long-chain fatty acids is expanded compared to the case where only long-chain fatty acids are adsorbed to the water-oil interface. There is a difference in the number of carbon atoms (difference in chain length) between short-chain fatty acids and long-chain fatty acids, so the interaction with hydrocarbons corresponding to the difference is weakened. It is speculated that the site where the interaction is weakened becomes the starting point and is easily cut off, thereby facilitating the formation of oil droplets. As a result, the dispersibility of the oil solution is improved and emulsification becomes easier.

[0018] The water-soluble metalworking oil of the embodiment contains a fatty acid having 8 to 10 carbon atoms. Fatty acid refers to a monocarboxylic acid of a hydrocarbon, and is a compound represented by the general formula CnHmCOOH. The fatty acid having 8 to 10 carbon atoms may be straight-chain or branched, preferably branched. The fatty acid having 8 to 10 carbon atoms may be any of a saturated fatty acid or an unsaturated fatty acid, preferably a saturated fatty acid. As the fatty acid having 8 to 10 carbon atoms, a branched saturated fatty acid is preferred.

[0019] The fatty acid having 8 to 10 carbon atoms preferably has 8 or 9 carbon atoms, and more preferably has 8 carbon atoms, from the viewpoint of water dispersibility.

[0020] Examples of the fatty acid having 8 to 10 carbon atoms include octanoic acid, nonanoic acid, decanoic acid, ethylhexanoic acid, isononanoic acid, isodecanoic acid, and neodecanoic acid, and ethylhexanoic acid, isononanoic acid, and neodecanoic acid are preferred. The fatty acid 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 acid 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, which is an index indicating the balance between hydrophilic groups and lipophilic groups in a compound molecule. In this specification, HLB is a value defined by the following calculation formula using the Griffin method. HLB value = 20 × [total chemical formula weight of hydrophilic part] / molecular weight For example, in octanoic acid (C 7 H 15 COOH; a straight-chain saturated fatty acid having 8 carbon atoms), the molecular weight = 144, the chemical formula weight of the hydrophilic part = 45 (carboxyl group (-COOH)), and therefore the HLB value is 6.25.

[0023] In the water-soluble metalworking oil, from the viewpoint of obtaining water dispersibility and an effect consistent with use, the content of the fatty acid having 8 to 10 carbon atoms is 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, further preferably 0.8% by mass or more and 12% by mass or less, further preferably 1.5% by mass or more and 11% by mass or less, further preferably 3.5% by mass or more and 10% by mass or less. The content when two or more kinds are used in combination refers to the total amount.

[0024] The water-soluble metalworking oil of the embodiment contains a fatty acid having at least 18 carbon atoms. The fatty acid having at least 18 carbon atoms contributes to the improvement of water dispersibility by coexisting with a fatty acid having 8 to 10 carbon atoms, and has the function of improving the liquid stability of the metalworking oil and its dilution.

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

[0026] The upper limit of the carbon number 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 saturated fatty acid having 18 or more carbon atoms or a polymer having an unsaturated fatty acid as a monomer. From the viewpoint of the synergistic effect with the fatty acid having 8 to 10 carbon atoms and the ease of availability, the fatty acid having 18 or more carbon atoms preferably has 18 carbon atoms.

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

[0028] From the viewpoint of water dispersibility, the difference in carbon number between the fatty acid having 18 or more carbon atoms and the fatty acid having 8 to 10 carbon atoms is preferably 8 or more, more preferably 9 or more, and even more preferably 10 or more.

[0029] In the water-soluble metalworking oil, from the viewpoint of liquid stability and water dispersibility, the content of fatty acids having 18 or more carbon atoms is 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, further preferably 3% by mass or more and 10% by mass or less, further preferably 4% by mass or more and 8% by mass or less, further preferably 4% by mass or more and 6% by mass or less. The content when two or more kinds are used in combination refers to the total amount.

[0030] In the water-soluble metalworking oil of the embodiment, from the viewpoint of water dispersibility, 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 from 0.05 to 10.0, more preferably from 0.10 to 5.0, further preferably from 0.15 to 4.0, further preferably from 0.35 to 3.0, further preferably from 0.80 to 2.5.

[0031] The water-soluble metalworking oil of the embodiment contains an alkali component. By neutralizing the fatty acid with the alkali component, the hydrophilicity of the fatty acid can be increased. Examples of the alkali component include organic amines and inorganic bases, preferably organic amines.

[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.), etc., preferably tertiary alkanolamines. Examples of the inorganic base include potassium hydroxide, sodium hydroxide, etc.

[0033] In the water-soluble metalworking oil, from the viewpoint of neutralization stability, the content of the alkali component 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, further preferably 0.5% by mass or more and 5% by mass or less, and still further preferably 1% by mass or more and 3% by mass or less. The content when two or more kinds are used in combination refers to the total amount.

[0034] In the water-soluble metalworking oil of the embodiment, from the viewpoint of water dispersibility, 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 to 15.0, more preferably 0.5 to 10.0, further preferably 1.0 to 8.0, and even more preferably 2.5 to 7.0.

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

[0036] In the water-soluble metalworking oil, from the viewpoint of processability and water dispersibility, the water content 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, further preferably 3% by mass or more and 8% by mass or less, and still further preferably 5% by mass or more and 7% by mass or less. The content when two or more kinds are used in combination refers to the total amount.

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

[0038] The water-soluble metalworking oil of the embodiment contains a base oil. As the base oil, for example, mineral oil, synthetic oil, animal and plant oils and fats, etc. can be cited, preferably mineral oil and synthetic oil. As mineral oil, spindle oil, engine oil, cylinder oil, paraffin oil, gear oil, etc. can be cited, preferably paraffin oil. As synthetic oil, synthetic oils such as hydrocarbon synthetic oil, ester synthetic oil, ether synthetic oil, etc. can be cited, preferably ester synthetic oil. As ester synthetic oil, esters of carboxylic acid (for example, carbon number 10 to 30, preferably carbon number 12 to 28, more preferably carbon number 15 to 25) and alcohol (for example, carbon number 1 to 30, preferably carbon number 1 to 25, more preferably carbon number 1 to 20) can be cited. The above-mentioned alcohol can be any one of a primary alcohol, a secondary alcohol and a tertiary alcohol, and can be any one of a monohydric alcohol, a dihydric alcohol, a trihydric alcohol and a tetrahydric alcohol. As ester synthetic oil, for example, methyl oleate, 2-ethylhexyl oleate, neopentyl glycol dioleate, trimethylolpropane trioleate, pentaerythritol tetraoleate, etc., preferably 2-ethylhexyl oleate. As animal and plant oils and fats, for example, animal oils and fats (lard, tallow, fish oil, etc.), vegetable oils and fats (rapeseed oil, soybean oil, palm oil, etc.), hydrogenated products thereof, etc. can be mentioned. The base oil can be used alone or in combination of two or more.

[0039] In the water-soluble metalworking oil, from the viewpoint of processability and water dispersibility, the content of the base oil 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, further preferably 10% by mass or more and 70% by mass or less, further preferably 30% by mass or more and 67% by mass or less, further preferably 50% by mass or more and 65% by mass or less. The content when two or more kinds are used in combination refers to the total amount.

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

[0041] The water-soluble metalworking oil of the embodiment can contain various additives as needed in addition to the above-mentioned essential components within the range that does not hinder the effect of the present invention. Examples of additives include surfactants, metal corrosion inhibitors, preservatives, alcohols, glycols, defoamers, etc.

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

[0043] As nonionic surfactants, for example, ethers, esters, amines, amides, etc. can be mentioned. As ethers, alkyl ethers, polyoxyalkylene ethers, polyoxyalkylene alkyl ethers, etc. can be mentioned, and polyoxyalkylene alkyl ethers are preferred. As esters, glycerol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxysorbitol fatty acid esters, etc. can be mentioned, and sorbitan fatty acid esters are preferred. As amines, polyoxyalkylene alkylamines, EO adducts of organic amines, etc. can be mentioned, and EO adducts of organic amines (for example, 1 to 20 moles) can be preferably mentioned. As amides, coconut fatty acid diethanolamide, oleic acid diethanolamide, etc. can be mentioned. As nonionic surfactants, polyoxyalkylene lauryl ethers, sorbitan monooleate, and EO adducts of laurylamine are preferred.

[0044] Examples of the anionic surfactant include polyoxyalkylene alkyl ether phosphoric acid, alkylbenzene sulfonic acid, α-olefin sulfonic acid, and salts thereof, and alkylbenzene sulfonate is preferred. As the anionic surfactant, sodium sulfonate is preferred.

[0045] Examples of cationic surfactants include quaternary ammonium salts (alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, alkyl dimethyl benzyl ammonium salts, etc.). Examples of amphoteric surfactants include Betaine Alkyl Betaine The surfactant may be used alone or in combination of two or more.

[0046] In the water-soluble metalworking oil, from the viewpoint of the stability of the stock solution and the stability of the diluted solution, 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, and more preferably 5% by mass or more and 20% by mass or less. The content when two or more kinds are used in combination refers to the total amount.

[0047] As metal corrosion inhibitors, for example, phosphoric acid esters, alkylphosphonic acids, sodium metasilicate, benzotriazole, etc. can be cited, preferably benzotriazole. The metal corrosion inhibitor can be used alone or in combination of two or more. In the water-soluble metalworking oil, the content of the metal corrosion inhibitor is, for example, 0.01 mass % or more and 5 mass % or less, preferably 0.05 mass % or more and 3 mass % or less. The content when two or more are used in combination refers to the total amount.

[0048] As the preservative, for example, organic amines can be mentioned. As the organic amine, cyclohexylamine, dicyclohexylamine, N-methyldicyclohexylamine, N,N-dimethylcyclohexylamine, dibenzylamine, 1,3-bisaminomethylcyclohexane, etc. can be mentioned, preferably dicyclohexylamine. The preservative can be used alone or in combination of two or more. In the water-soluble metalworking oil, the content of the preservative is, for example, 0.1% by mass or more and 15% by mass or less, preferably 0.5% by mass or more and 12% by mass or less. The content when two or more are used in combination refers to the total amount.

[0049] Examples of alcohols include benzyl alcohol, phenoxyethanol, phenoxypropanol, decanol, dodecanol, tetradecanol, palmityl alcohol, stearyl alcohol, oleyl alcohol, and the like, preferably benzyl alcohol. Alcohols may be used alone or in combination of two or more. In water-soluble metalworking oils, from the perspective of stock solution stability, the content of alcohols is, for example, 0.1% by mass or more and 10% by mass or less, preferably 1% by mass or more and 5% by mass or less. The content when two or more alcohols are used in combination refers to the total amount.

[0050] As diols, for example, diethylene glycol, 1,2-propylene glycol, 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. can be cited, preferably diethylene glycol mono-2-ethylhexyl ether. Diols can be used alone or in combination of two or more. In water-soluble metalworking oils, from the viewpoint of stock solution stability, the content of diols is, for example, 0.1% by mass or more and 10% by mass or less, preferably 0.5% by mass or more and 5% by mass or less. The content when two or more are used in combination refers to the total amount.

[0051] As the defoamer, for example, silicone defoamers, higher alcohol defoamers, polyether defoamers, and metal soap defoamers can be cited, preferably silicone defoamers. The defoamer can be used alone or in combination of two or more. In the water-soluble metalworking oil, the content of the defoamer is, for example, 0.01% by mass or more and 5% by mass or less, preferably 0.05% by mass or more and 3% by mass or less. The content when two or more are used in combination refers to the total amount.

[0052] In the water-soluble metalworking oil of the embodiment, in addition to the above-mentioned essential components, as long as it does not hinder the effect of the present invention, from the viewpoint of improving lubricity, corrosion resistance and rust resistance, fatty acids other than fatty acids with 8 to 10 carbon atoms and fatty acids with 18 or more carbon atoms can be contained. As fatty acids of arbitrary components, for example, fatty acids with 7 or less carbon atoms, fatty acids with 11 to 17 carbon atoms, etc. can be cited. The fatty acids of arbitrary components can be used alone or in combination of two or more. In the water-soluble metalworking oil, the content of the fatty acid of the arbitrary component is, for example, less than 3% by mass, preferably less than 1% by mass, and more preferably less than 0.1% by mass. The content when two or more are used in combination refers to the total amount.

[0053] The water-soluble metalworking oil of the embodiment is manufactured by mixing the above-mentioned components. The order of adding the components and the mixing method are not particularly limited. For example, the water-soluble metalworking oil can be mixed by stirring the above-mentioned components. The stirring conditions are not particularly limited, for example, a stirrer can be used to stir for about 5 minutes to 20 minutes at room temperature and a rotation speed of about 100 rpm.

[0054] The water-soluble metalworking oil of the embodiment can be produced by post-adding (additionally adding) a fatty acid having 8 to 10 carbon atoms to the water-soluble metalworking oil containing the fatty acid having 18 or more carbon atoms, an alkali component, water, and a base oil.

[0055] The water-soluble metalworking oil of the embodiment can be used directly for processing a workpiece including metal, but can be particularly suitably used as a stock solution for a metalworking fluid obtained by diluting the water-soluble metalworking oil with dilution water because of its excellent water dispersibility.

[0056] [Metalworking fluid] The metalworking fluid of the embodiment contains the water-soluble metalworking oil and dilution water. Examples of the dilution water include tap water, industrial water, ion exchange water, distilled water, sterilized purified water, etc., and 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 with dilution water can be appropriately adjusted according to the composition of the water-soluble metalworking oil and the performance required during metal processing. The dilution ratio is not limited, and it is usually preferably diluted to 1.5 times or more and 100 times or less for use. From the viewpoint of water dispersibility and liquid stability, the dilution ratio is more preferably 5 times or more and 50 times or less, and further 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 a water-soluble metalworking oil with dilution water. The dilution method of the water-soluble metalworking oil is not particularly limited, and dilution can be performed by a known method. For example, the mixture may be mixed by stirring using a rotor or a propeller or manually, or the water-soluble metalworking oil may be added to a container containing dilution water and stirred by natural convection to be diluted.

[0060] The metalworking fluid according to the embodiment has excellent dispersibility and processability, and can suppress the occurrence of stickiness in the device using the metalworking fluid, so it can be suitably used for various metal processing such as cutting, grinding, lapping, cutting, rolling, stamping, rolling, wire drawing, drawing and ironing of a workpiece including metal. Examples of the workpiece include iron-based metals and their alloys, stainless steels, aluminum, aluminum alloys, magnesium, magnesium alloys, copper, copper alloys and non-ferrous metals and their alloys.

[0061] [Metal processing method] The metalworking method according to the embodiment uses the metalworking fluid to process a workpiece containing a metal. Examples of the processing of the workpiece include cutting, grinding, lapping, cutting, rolling, stamping, rolling, wire drawing, drawing, and ironing. The metalworking fluid is supplied to the processing point in a liquid or mist state, for example. Examples of the workpiece include the metals mentioned above.

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

[0063] Hereinafter, the present invention will be described in more detail 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] Weigh each component according to the composition shown in Table 2 so that the content of octanoic acid as a fatty acid with 8 to 10 carbon atoms is 2.0 parts by mass relative to 100 parts by mass of a blank containing a fatty acid with 18 or more carbon atoms, an alkali component, water, a base oil and an additive. Use a stirrer (15 mm × 35 mm, rugby type) and a stirrer ("SLOW STIRRER SW-600N-1" manufactured by Nissin Chemical Co., Ltd.) to stir and mix them at 5 scales at room temperature for about 15 minutes to obtain the water-soluble metalworking oil of Example 1-1. The composition of the blank is shown in Table 1. In Example 1-1, the pH of the metalworking fluid diluted to 5 parts by mass with tap water is 7.0. The pH is measured using a pH meter ("F-52" manufactured by HORIBA).

[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 proportions of the components in the water-soluble metalworking oil were set as shown in Tables 2 to 5. The content of the fatty acid having 8 to 10 carbon atoms was 1.0 parts 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, relative to 100 parts by mass of the blank. Comparative Examples 1 to 3 correspond to blanks to which no fatty acid having 8 to 10 carbon atoms and no comparative compound were added.

[0066] (Water dispersibility evaluation) In a flat-bottomed beaker of 500 mL capacity, 380.0 g of tap water and the above-mentioned stirring bar as dilution water were added respectively, and 20.0 g of each water-soluble metalworking oil (stock solution) was added from a position about 15 cm from the water surface. Then, using the above-mentioned agitator, stir and mix at 3 scales for 10 seconds, and let stand for 30 seconds after stirring stops. After standing, the appearance of the diluent was visually confirmed and evaluated according to the following criteria. In the case 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 suspended matter was observed on the surface of the dilution. B: A small amount of suspended matter was observed on the surface of the dilution. C: A moderate amount of suspended matter was observed on the surface of the dilution. D: A large amount of suspended matter was observed on the surface of the dilution.

[0067] Figure 1 This is an image for explaining the evaluation criteria of water dispersibility. Figure 1 This is an illustrative image for explaining the evaluation criteria and does not limit the actual evaluation results. The dotted line in the image indicates the area of ​​suspended matter.

[0068] The details of the components shown in Tables 1 to 5 are as follows. <Fatty acids with 18 or more carbon atoms> Oleic acid (carbon number 18) <Alkali ingredients> N-Cyclohexyldiethanolamine <Base oil> Paraffinic mineral oil 2-Ethylhexyl Oleate <Additives> Surfactants Nonionic surfactant 1: Laurylamine EO15 molar 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 Diols: "2-Ethylhexyldiglycol" manufactured by Nippon Emulsifier Co., Ltd. Defoamer: Silicone defoamer <Fatty acids> Fatty acid A1: Caprylic acid (8 carbon atoms, straight chain, HLB 6.3) Fatty acid A2: 2-ethylhexanoic acid (8 carbon atoms, branched, HLB 6.3) Fatty acid A3: Nonanoic acid (9 carbon atoms, straight chain, HLB 5.7) Fatty acid A4: Isononanoic acid (9 carbon atoms, branched, HLB 5.7) Fatty acid A5: Capric acid (10 carbon atoms, straight chain, HLB 5.2) Fatty acid A6: Neodecanoic acid (10 carbon atoms, branched, HLB 5.2) Fatty acid B1: polymer of hydroxyunsaturated fatty acid (72 carbon atoms, branched, HLB 0.8) Fatty acid B2: stearic acid (18 carbon atoms, straight chain, HLB 3.2) It should be noted that fatty acids A1 to A6 are fatty acids having 8 to 10 carbon atoms, and fatty acids B1 and B2 are comparative compounds.

[0069] [Table 1] Table 1

[0070] [Table 2]

[0071] [Table 3]

[0072] [Table 4]

[0073] [Table 5]

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

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

[0076] As described above, it was confirmed that the water-soluble metalworking oil of the present invention has excellent water dispersibility.

Claims

1. A water-soluble metalworking oil, characterized in that: Contains fatty acids having 8 to 10 carbon atoms, fatty acids having 18 or more carbon atoms, an alkali component, water, and a base oil.

2. The water-soluble metalworking oil according to claim 1, characterized in that: The difference in carbon number 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 claim 1 or 2, characterized in that: The fatty acid having 8 to 10 carbon atoms includes branched fatty acids.

4. The water-soluble metalworking oil according to claim 1 or 2, characterized in that: 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 claim 1 or 2, characterized in that: 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, ie, 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 claim 1 or 2, characterized in that: The alkaline component is at least one selected from an inorganic base and an organic amine.

7. The water-soluble metalworking oil according to claim 1 or 2, characterized in that: The fatty acid having 18 or more carbon atoms is oleic acid.

8. A metalworking fluid, characterized in that: The water-soluble metalworking oil according to any one of claims 1 to 7 is diluted with water.

9. A metal processing method, characterized in that: A workpiece containing metal is processed using a metalworking fluid obtained by diluting the water-soluble metalworking fluid according to any one of claims 1 to 7 with water.

10. A method for improving the dispersibility of a water-soluble metalworking oil, characterized in that: The method comprises the 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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