Metal processing oil agent, metal processing fluid, method of application, and method for preventing precipitation

Abstract

To provide a metal processing oil agent or the like that can prevent the formation of precipitates.SOLUTION: The metal processing oil agent contains branched fatty acids, alkanolamines, and water, and is used in the presence of zinc.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a metalworking oil, a metalworking fluid, a method of use, and a method for suppressing precipitation.

Background Art

[0002] In the field of metalworking such as cutting and grinding, metalworking oils are used. Metalworking oils include oil-based working oils and water-soluble working oils. In recent years, water-soluble working oils have been widely used because of their excellent cooling performance and low fire risk. As such a water-soluble metalworking oil, for example, a metalworking oil using fatty acids has been proposed to enhance the stock solution stability (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present inventor has found a new problem that when a metalworking oil containing fatty acids or a dilution thereof is applied to a metal material containing zinc, precipitates are generated on the surface of the metal material. Metalworking oils are supplied to the object to be processed through, for example, pipes plated with zinc during metalworking. When precipitates are generated under such conditions, there is a risk of clogging of pipes, filters, etc., and adhesion to the object to be processed.

[0005] The main object of the present disclosure is to provide a metalworking oil or the like that can suppress the generation of precipitates.

Means for Solving the Problems

[0006] Aspects of the present disclosure for solving the above problems are as follows.

[0007] [1] A metalworking fluid containing a branched fatty acid, an alkanolamine, and water, and used in the presence of zinc. [2] The metalworking fluid according to [1], wherein the branched fatty acid has 4 to 18 carbon atoms. [3] The metalworking fluid according to [1] or [2], wherein the alkanolamine is ethanolamines. [4] The metalworking fluid according to any one of [1] to [3], wherein the content of the branched fatty acid is 0.1% by mass or more and 20% by mass or less. [5] The metalworking fluid according to any one of [1] to [4], wherein the content of the alkanolamine is 0.1% by mass or more and 40% by mass or less. [6] The metalworking fluid according to any one of [1] to [5], further containing at least one selected from the group consisting of a corrosion inhibitor, a chelating agent, a preservative, glycols, and a nonionic surfactant. [7] The metalworking fluid according to any one of [1] to [6], substantially free of straight-chain fatty acids. [8] A metalworking fluid obtained by diluting the metalworking fluid according to any one of [1] to [7] with water. [9] A method of use, wherein a metalworking fluid containing a branched fatty acid, an alkanolamine, and water or a metalworking fluid obtained by diluting the metalworking fluid with water is used in the presence of zinc.

[10] A method for suppressing precipitation of a metalworking fluid used in the presence of zinc, the method including a step of blending a branched fatty acid, an alkanolamine, and water. [Effect of the Invention]

[0008] According to the present disclosure, it is possible to provide a metalworking fluid or the like capable of suppressing the generation of precipitates. [Brief Description of the Drawings]

[0009]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0010] 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 modifications within the scope of the claims and the scope equivalent to the claims. Also, 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" can also be included in the numerical range.

[0011] 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 is in a form having a substituent, it means the total number of carbon atoms including this substituent.

[0012] [Metalworking Fluid] The metalworking fluid of this embodiment contains a branched fatty acid, an alkanolamine, and water. By containing a branched fatty acid in the metalworking fluid, it is possible to suppress the generation of precipitates that occur when applied to a metal material containing zinc, particularly the generation of zinc fatty acid salts.

[0013] The present inventor analyzed the precipitates generated on the workpiece when applying a metalworking fluid containing a fatty acid or a dilution thereof to a metal material containing zinc, and found that the precipitate is a salt of a fatty acid and zinc. Then, under the condition of using a metalworking fluid containing a fatty acid for a metal material containing zinc, intensive studies were conducted to suppress the generation of precipitates, and it was found that by containing a branched fatty acid, the generation of a salt of a fatty acid and zinc can be suppressed. Note that "applying (a metalworking fluid or its dilution) to a metal material containing zinc" means using the metalworking fluid or its dilution in an environment where zinc can dissolve in the metalworking fluid or its dilution during use. Such environments include, for example, (1) an environment where the metalworking fluid or its dilution is supplied to the object to be processed through zinc-plated pipes or the like inside the equipment, and (2) an environment where an object to be processed containing zinc is processed using the metalworking fluid or its dilution. In such environments, since the metalworking fluid or its dilution comes into contact with zinc, zinc can dissolve in the metalworking fluid or its dilution. Therefore, under the condition that zinc (specifically zinc ions) is present in the metalworking fluid or its dilution, the object to be processed will be processed.

[0014] Although the mechanism by which the metalworking fluid of the present disclosure is excellent in precipitation inhibition is not clear, it is presumed as follows. As described above, the precipitate generated when a metalworking fluid containing a fatty acid is used in the presence of zinc is a salt of the fatty acid in the metalworking fluid and zinc dissolved in the metalworking fluid. Most solids have a structure in which molecules and atoms are regularly and periodically arranged. It is presumed that the more easily molecules and atoms are arranged densely without gaps, the more likely they are to form a solid and crystallize. When chain hydrocarbons are arranged, branched hydrocarbons having a branched structure are more likely to be arranged without gaps and form a densely packed structure than straight-chain hydrocarbons having no branched structure. Therefore, by using a fatty acid having a branched hydrocarbon chain as the fatty acid causing the precipitate, it is possible to suppress the dense arrangement of the fatty acid and the crystallization more than when using a fatty acid having a straight-chain hydrocarbon chain. For this reason, it is presumed that even when the metalworking fluid takes in zinc ions, precipitation of the salt of zinc ions and fatty acids can be suppressed.

[0015] The metalworking fluid of the present embodiment contains a branched fatty acid. By containing a fatty acid, it is possible to suppress the generation of precipitates, improve the stability of the undiluted solution, and adjust the pH favorably.

[0016] A fatty acid is a monovalent carboxylic acid of hydrocarbon and is a compound represented by the general formula CnHmCOOH. The branched fatty acid may be either a branched saturated fatty acid or a branched unsaturated fatty acid.

[0017] From the viewpoint of precipitation inhibition, the branched fatty acid preferably has 4 to 18 carbon atoms, more preferably 4 to 10 carbon atoms, and still more preferably 8 to 10 carbon atoms.

[0018] Examples of the branched fatty acid include isobutyric acid, 2-methylbutyric acid, 3-methylbutyric acid, 2,2-dimethylpropionic acid, 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 2,2-dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 3,3-dimethylpentanoic acid, 3,4-dimethylpentanoic acid, 4,4-dimethylpentanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 5-methylhexanoic acid, octylic acid (2-ethylhexanoic acid), 2,2-dimethylhexanoic acid, 2-methylheptanoic acid, 4-methyl-n-octanoic acid, isononanoic acid (3,5,5-trimethylhexanoic acid), 2-ethyl-2,5-dimethylhexanoic acid, 2-isopropyl-2,4-dimethylpentanoic acid, 2,2-dimethyloctanoic acid, 2,2-diethylhexanoic acid, 9,9-dimethyldecanoic acid, 2,2,3,5-tetramethylhexanoic acid, 4-methylnonanoic acid, 3,7-dimethyl-6-octenoic acid, 4-tetrabutylbenzoic acid, 2-hexyldecanoic acid, 2-methylhexadecanoic acid, 2,2,4,8,10,10-hexamethylundecane-5-carboxylic acid, 2-ethylhexadecanoic acid, neodecanoic acid, etc. Preferably, they are octylic acid, isononanoic acid, and neodecanoic acid. The branched fatty acid may be used alone or in combination of two or more.

[0019] Branched fatty acids are preferably in an amount of 0.1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 18% by mass or less, still more preferably 5% by mass or more and 15% by mass or less, and even more preferably 8% by mass or more and 11% by mass or less from the viewpoints of precipitation inhibition, neat stability, and pH adjustment in the metalworking fluid. When two or more are used in combination, the content means the total amount.

[0020] The metalworking fluid of this embodiment contains an alkanolamine. The alkanolamine has a function of neutralizing fatty acids. The alkanolamine is not particularly limited as long as it has 1 to 3 saturated hydrocarbon groups in which hydrogen atoms are substituted with hydroxyl groups bonded to a nitrogen atom. When using a dialkanolamine or trialkanolamine having 2 or 3 saturated hydrocarbon groups substituted with hydroxyl groups, the saturated hydrocarbon groups substituted with a plurality of hydroxyl groups may be the same or different.

[0021] The saturated hydrocarbon group of the alkanolamine may be linear, branched, or cyclic, and is preferably linear. From the viewpoint of precipitation inhibition, the number of carbon atoms of the saturated hydrocarbon group of the alkanolamine is preferably 1 to 6, more preferably 1 to 4, and still more preferably 2.

[0022] Examples of the alkanolamine include ethanolamines, propanolamines, butanolamines, etc., and from the viewpoint of precipitation inhibition, ethanolamines are preferred.

[0023] Specific examples of ethanolamines include monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine, N-isopropylethanolamine, N-butyldiethanolamine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-(dipropylamino)ethanol, 2-(diisopropylamino)ethanol, 2-(dibutylamino)ethanol, N-cyclohexyldiethanolamine, etc. Preferably, they are monoethanolamine, diethanolamine, triethanolamine, N-butylethanolamine, and N-cyclohexyldiethanolamine.

[0024] Specific examples of propanolamines include monopropanolamine, dipropanolamine, tripropanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 3-amino-1-propanol, 2-amino-1-propanol, 1-amino-2-propanol, 2-amino-2-methyl-1-propanol, 1-amino-2-methyl-2-propanol, 2-amino-2-ethyl-1-propanol, 1-amino-2-ethyl-2-propanol, N-methylpropanolamine, N-ethylpropanolamine, N-propylpropanolamine, N-propylisopropanolamine, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, etc.

[0025] Specific examples of butanolamines include 2-amino-1-butanol, 3-amino-1-butanol, 4-amino-1-butanol, 1-amino-2-butanol, 1-amino-3-butanol, N-methylbutanolamine, N-ethylbutanolamine, N-propylbutanolamine, N-isopropylbutanolamine, N-butylbutanolamine, 4-dimethylamino-1-butanol, and the like. The alkanolamine may be used alone or in combination of two or more.

[0026] From the viewpoints of neutralization and precipitation inhibition in the metalworking fluid, the alkanolamine is preferably 0.1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 30% by mass or less, still more preferably 5% by mass or more and 25% by mass or less, and even more preferably 10% by mass or more and 21% by mass or less. When two or more are used in combination, the content means the total amount.

[0027] In the metalworking fluid of the embodiment, the mass ratio of the content of the alkanolamine to the content of the branched fatty acid (alkanolamine / branched fatty acid) is preferably 0.1 or more and 7 or less, more preferably 0.2 or more and 5 or less, still more preferably 0.6 or more and 3 or less, even more preferably 0.9 or more and 2.5 or less, and most preferably 1.4 or more and 1.9 or less, from the viewpoint of precipitation inhibition.

[0028] The 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 it may be hard water or soft water. The water may be used alone or in combination of two or more.

[0029] From the viewpoints of precipitation inhibition, stock solution stability, and workability in the metalworking fluid, the water content is preferably 0.1% by mass or more and 90% by mass or less, more preferably 5% by mass or more and 85% by mass or less, still more preferably 30% by mass or more and 60% by mass or less, and even more preferably 45% by mass or more and 55% by mass or less. When two or more are used in combination, the content means the total amount.

[0030] In the metalworking fluid of the embodiment, the mass ratio of the water content to the content of the branched fatty acid (water / branched fatty acid) is preferably 1 or more and 20 or less, more preferably 2 or more and 15 or less, still more preferably 3 or more and 10 or less, and even more preferably 4 or more and 7 or less from the viewpoint of precipitation inhibition.

[0031] In the metalworking fluid of the embodiment, the mass ratio of the water content to the content of the alkanolamine (water / alkanolamine) is preferably 0.5 or more and 20 or less, more preferably 1 or more and 15 or less, still more preferably 2 or more and 10 or less, and even more preferably 2.5 or more and 5 or less from the viewpoint of precipitation inhibition.

[0032] In addition to the above essential components, the metalworking fluid of the embodiment can contain other optional components as needed within a range that does not interfere with the effects of the present invention. Examples of the optional components include corrosion inhibitors, chelating agents, preservatives, glycols, nonionic surfactants, base oils, and the like. These may be used alone or in combination of two or more.

[0033] Examples of the corrosion inhibitor include phosphate esters, alkylphosphonic acids, alkylsulfonates, sodium metasilicate, dibasic acids, dibasic acid salts, benzotriazole-based compounds, and the like, and dibasic acids and benzotriazole-based compounds are preferred. The content of the corrosion inhibitor is, for example, 0.1% by mass or more and 10% by mass or less, preferably 0.5% by mass or more and 3% by mass or less in the metalworking fluid.

[0034] Examples of the chelating agent include chelating agents such as aminocarboxylic acid-based and phosphonic acid-based chelating agents, and preferably aminocarboxylic acid-based chelating agents. Specific examples of the chelating agent include ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, N-(2-hydroxyethyl)iminodiacetic acid, N,N-di(2-hydroxyethyl)glycine, glutamic acid diacetic acid, aspartic acid diacetic acid, methylglycine diacetic acid, (S,S)-ethylenediaminedisuccinic acid, hydroxyethylidene diphosphonic acid, phosphonobutane triacetic acid, nitrilotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and salts thereof. The content of the chelating agent in the metalworking oil is, for example, 0.01% by mass or more and 5% by mass or less, preferably 0.5% by mass or more and 3% by mass or less.

[0035] Examples of the preservative include triazine-based compounds, isothiazoline-based compounds, benzisothiazoline-based compounds, morpholine-based compounds, and pyridine-based compounds, and preferably triazine-based compounds. The content of the preservative in the metalworking oil is, for example, 0.1% by mass or more and 5% by mass or less, preferably 0.5% by mass or more and 5% by mass or less.

[0036] Examples of the glycols include polyoxyalkylene glycol, 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 preferably polyoxyalkylene glycol. The content of the glycols in the metalworking oil is, from the viewpoint of lubricity, for example, 1% by mass or more and 50% by mass or less, preferably 5% by mass or more and 20% by mass or less.

[0037] Examples of nonionic surfactants include ethers, esters, amines, amides, etc., and ethers are preferred. Examples of ethers include alkyl ethers, polyoxyalkylene ethers, polyoxyalkylene alkyl ethers, etc., and polyoxyalkylene alkyl ethers are preferred. Examples of esters include glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxysorbitol fatty acid esters, etc. Examples of amines include polyoxyalkylene alkyl amines, EO adducts of organic amines, etc. Examples of amides include coconut oil fatty acid diethanolamide, oleic acid diethanolamide, etc. The content of the nonionic surfactant in the metalworking fluid is, for example, 0.1% by mass or more and 30% by mass or less, preferably 1% by mass or more and 10% by mass or less.

[0038] Examples of the base oil include mineral oil, synthetic oil, animal and vegetable oils and fats, etc. The content of the base oil in the metalworking fluid is, for example, 0.1% by mass or more and 3% by mass or less, preferably 0.1% by mass or more and 0.5% by mass or less.

[0039] The metalworking fluid of the embodiment may also contain a linear fatty acid as necessary within a range that does not interfere with the effects of the present invention. When containing a linear fatty acid, the content is preferably 1% by mass or less, more preferably 0.5% by mass or less. It is preferable that the metalworking fluid of the embodiment substantially does not contain a linear fatty acid.

[0040] In this specification, "substantially not contained" means that the linear fatty acid is not actively added to the metalworking fluid of the embodiment, and it is not intended that no linear fatty acid is contained at all. Preferably, it means that the content of the linear fatty acid is 0.1% by mass or less in the metalworking fluid.

[0041] The metalworking oil agent of the embodiment is manufactured by mixing the above components. The addition order and mixing method of each component are not particularly limited. For example, the metalworking oil agent may be mixed by stirring the above components. The stirring conditions are not particularly limited, but for example, using a stirrer, it may be stirred at a rotation speed of about 100 rpm for about 5 to 20 minutes at room temperature.

[0042] The metalworking oil agent of the embodiment is in a water-soluble state and can be used directly for metal processing.

[0043] [Metalworking fluid] The metalworking fluid of the embodiment is obtained by diluting the above-mentioned metalworking oil agent with water as a stock solution. The metalworking fluid can be used for metal processing as a coolant. Examples of the water for dilution 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 for dilution may be used alone or in combination of two or more.

[0044] The dilution ratio when diluting the metalworking oil agent with water can be appropriately adjusted according to the composition of the metalworking oil agent and the performance required during metal processing. 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 35 times or less.

[0045] The dilution method of the 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 metalworking oil agent may be put into a container containing water and diluted by stirring by natural convection.

[0046] The pH of the metalworking oil agent (stock solution) and the metalworking fluid of the embodiment is preferably 7 or more and 10 or less, and more preferably 7.5 or more and 9 or less, from the viewpoints of corrosion inhibition and corrosion protection of the workpiece.

[0047] The metalworking oil and metalworking fluid of the embodiment are excellent in the ability to suppress the formation of deposits when applied to metal materials containing zinc. Therefore, they can be suitably used for metalworking in the presence of zinc, more specifically, in an environment where zinc elutes into the metalworking oil or metalworking fluid. Examples of the processing methods include cutting, grinding, polishing, bending, pressing, drawing, and ironing. Among these processing methods, they can be particularly suitably used for drawing, ironing, etc., in which equipment containing zinc (such as piping) is used.

[0048] Examples of the workpiece materials include ferrous metals and their alloys, stainless steels, aluminum, aluminum alloys, magnesium, magnesium alloys, copper, copper alloys, non-ferrous metals such as zinc and zinc alloys, and their alloys. As the workpiece material, aluminum or an aluminum alloy is particularly preferred.

[0049] [Method of using the metalworking oil or metalworking fluid] The method of using the metalworking oil of the embodiment is such that the above-mentioned metalworking oil or a metalworking fluid obtained by diluting the metalworking oil with water can be used in the presence of zinc. The metalworking oil or metalworking fluid is supplied to the workpiece, for example, while circulating through piping containing zinc. During metalworking, the metalworking oil or metalworking fluid is brought into contact with the processing part of the workpiece, for example, in a liquid state or a mist state, while performing the processing. The metalworking oil and metalworking fluid of the embodiment can favorably suppress the generation of deposits when applied to metal materials containing zinc. Note that the metal material containing zinc is not limited to equipment and may also be the workpiece.

[0050] [Method for suppressing deposition of the metalworking oil] The deposition suppression method of the embodiment is a method for suppressing the deposition of a metalworking oil used in the presence of zinc, and includes a step of blending a branched fatty acid, an alkanolamine, and water. As described above, since the branched fatty acid is contained in the metalworking oil, the generation of deposits when used in the presence of zinc can be favorably suppressed. [Examples]

[0051] 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.

[0052] (Preparation of Metalworking Fluid) [Example 1] According to the formulation composition shown in Table 1 (expressed in mass %), each component was weighed. Using a stirrer, these were stirred and mixed uniformly at room temperature to obtain the metalworking fluid of Example 1.

[0053] [Examples 2 to 12, Comparative Examples 1 to 7, Reference Example 1] Except that the formulation composition of the metalworking fluid was made as shown in Tables 1 to 3, the metalworking fluids of each example, comparative example, and reference example were prepared in the same manner as in Example 1. In addition, the total number of moles of the fatty acids used in each example and comparative example in Tables 1 to 3 was the same.

[0054] Details of each component shown in Tables 1 to 3 are as follows. [Fatty Acid] Neodecanoic acid (carbon number 10, branched fatty acid) Isononanoic acid (carbon number 9, branched fatty acid) Octylic acid (carbon number 8, branched fatty acid) Tall oil fatty acid (mixed fatty acid mainly composed of oleic acid (carbon number 18, straight-chain fatty acid)) Myristic acid (carbon number 14, straight-chain fatty acid) Lauric acid (carbon number 12, straight-chain fatty acid) Decanoic acid (carbon number 10, straight-chain fatty acid) Nonanoic acid (carbon number 9, straight-chain fatty acid) Octanoic acid (carbon number 8, straight-chain fatty acid) [Corrosion Inhibitor] Dibasic acid Benzotriazole-based compound [Chelating Agent] Aminocarboxylic acid-based chelating agent [Antiseptic] Triazine-based compound [Glycols] Polyoxyalkylene glycol <Nonionic surfactant> Polyoxyalkylene alkyl ether

[0055] [Evaluation of precipitation inhibition] As the test solution, a mixture obtained by stirring and mixing 1.50 g of the metalworking fluid of each example, comparative example, and reference example, 48.25 g of tap water, and 0.25 g of machine oil ("Cosmo Gear SE150" manufactured by Cosmo Oil Lubricants Co., Ltd.) was used. The test solution was put into a sample bottle with a capacity of 100 mL, and a zinc-plated steel pipe (cylindrical pipe with a height of 30 mm, an outer diameter of φ17 mm, and an inner diameter of φ13 mm) degreased with acetone and hexane was immersed in the test solution and left standing in a constant temperature machine at 40 °C for 14 days. After standing, the appearance of the pipe was visually confirmed and evaluated according to the following criteria. The evaluation results are shown in Tables 1 to 3. [Evaluation criteria] 〇: Slight precipitation is generated (precipitation is generated on 20% or less of the total surface area of the pipe) ×: A large amount of precipitation is generated (precipitation is generated on 80% or more of the total surface area of the pipe)

[0056] [Measurement of pH] The metalworking fluids (stock solutions) of Examples 1 to 3, Comparative Examples 1 to 6, and Reference Example 1 described above were diluted with ion-exchanged water to 3 mass%. The pH of the obtained diluted solution was measured using a pH meter ("F-52" manufactured by HORIBA). The measurement results are shown in Table 1.

[0057] [Evaluation of stock solution stability] Regarding the metalworking fluids (stock solutions) of the examples, comparative examples, and reference examples prepared as described above, the appearance of each metalworking fluid immediately after preparation was visually confirmed and evaluated according to the following criteria. The evaluation results are shown in Tables 1 to 3. [Evaluation criteria] 〇: Not stratified and transparent ×: Stratification is observed and it is cloudy

[0058] Figure 1 is an image explaining the evaluation criteria for precipitation inhibition, and Figure 2 is an image explaining the evaluation criteria for stock solution stability. Note that Figures 1 and 2 are exemplary images for explaining the evaluation criteria and do not limit the actual evaluation results.

[0059]

Table 1

[0060]

Table 2

[0061]

Table 3

[0062] As is clear from Tables 1 to 3, it can be seen that in the examples containing branched fatty acids, alkanolamines, and water, the precipitation inhibitory property is good. Furthermore, it can be seen that in the examples, the stock solution stability is good. On the other hand, in the comparative examples in which linear fatty acids were blended instead of branched fatty acids, the precipitation inhibitory property was poor. Also, in the reference examples not containing fatty acids, the stock solution stability was poor.

[0063] In any of Examples 1 to 3 and Examples 4 to 6 in which the types of branched fatty acids were varied, or Examples 7 to 12 in which the types of alkanolamines were varied, it was confirmed that they are excellent in the precipitation inhibitory property when applied to zinc.

Claims

1. A metalworking fluid containing a branched fatty acid, an alkanolamine, and water, and used in the presence of zinc.

2. The metalworking fluid according to Claim 1, wherein the branched fatty acid has 4 to 18 carbon atoms.

3. The metalworking fluid according to Claim 1 or Claim 2, wherein the alkanolamine is ethanolamines.

4. The metalworking fluid according to Claim 1 or Claim 2, wherein the content of the branched fatty acid is 0.1% by mass or more and 20% by mass or less.

5. The metalworking fluid according to Claim 1 or Claim 2, wherein the content of the alkanolamine is 0.1% by mass or more and 40% by mass or less.

6. The metalworking fluid according to Claim 1 or Claim 2, further containing at least one selected from the group consisting of a corrosion inhibitor, a chelating agent, a preservative, glycols, and a nonionic surfactant.

7. The metalworking fluid according to Claim 1 or Claim 2, substantially free of a straight-chain fatty acid.

8. A metalworking liquid obtained by diluting the metalworking fluid according to Claim 1 with water.

9. A method of use, wherein a metalworking fluid containing a branched fatty acid, an alkanolamine, and water or a metalworking liquid obtained by diluting the metalworking fluid with water is used in the presence of zinc.

10. A method for suppressing precipitation of a metalworking fluid used in the presence of zinc, the method including a step of blending a branched fatty acid, an alkanolamine, and water.

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