Metal processing oil composition and metal processing method

Abstract

To provide a metal processing oil composition that suppresses metal elution and has excellent corrosion prevention properties, and a metal processing method using this metal processing oil composition.SOLUTION: A metal processing oil composition comprises an oil-in-water type emulsion containing a mineral oil with an aniline point of 60°C or higher and 84°C or lower and water, wherein the average oil droplet diameter of the emulsion is 90 nm or more and 350 nm or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a metalworking oil composition and a metalworking method, and more particularly to a metalworking oil composition which inhibits the elution of metals, particularly copper-based or zinc-based metals, and has excellent corrosion prevention properties, and to a metalworking method using the metalworking oil composition. [Background technology]

[0002] Water-soluble metalworking oil compositions are used in the field of metalworking such as cutting and grinding. Water-soluble metalworking oil compositions are generally made by blending base oil, surfactant, antioxidant, water, etc. according to the purpose, and are often used by diluting with water, for example, as a coolant liquid. This causes a problem that the material to be worked is easily corroded.

[0003] Therefore, in order to suppress the corrosion of the workpiece, a corrosion inhibitor has been conventionally blended into the metalworking oil composition. The corrosion inhibitor has the effect of preventing the metal of the workpiece from dissolving as ions into the water contained in the metalworking oil composition. Patent Document 1 discloses a rust inhibitor composition containing an oil-soluble organometallic salt, benzotriazole, and an organic amine as an anticorrosive component. According to Patent Document 1, the rust inhibitor composition uses an oil-soluble organometallic salt and benzotriazole in combination, and while maintaining a strong bond due to the complex formation between benzotriazole and the metal, it is possible to form a multiple rust inhibitor layer of the oil-soluble organometallic salt, and even if the content of the rust inhibitor in the water dilution solution is very small, excellent corrosion inhibitor performance is exhibited. And it is described that the rust inhibitor composition of Patent Document 1 can exhibit extremely stable corrosion inhibitor performance not only for aluminum alloys with high aluminum purity, but also for aluminum alloys such as aluminum die castings containing a large amount of copper.

[0004] In addition, when disposing of a water-soluble metalworking oil composition, it is necessary to remove organic matter, metals, etc. from the coolant liquid and to discharge it as clean water below the wastewater standard value based on the ordinance of each river, which is a heavy burden on wastewater treatment. From this viewpoint, Patent Document 2 discloses a water-soluble cutting oil containing a mineral oil or synthetic oil with an aniline point of 85 to 110°C, an amine, an organic acid, and a nonionic surfactant. According to Patent Document 2, the water-soluble cutting oil has good wastewater treatability and can reduce equipment attack. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6286642 [Patent Document 2] Patent No. 5916589 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, benzotriazole is used as a corrosion inhibitor, but the corrosion inhibitor effect is limited to certain metal materials, and the corrosion inhibitor effect is particularly insufficient for brass. In addition, metalworking oil compositions containing mineral oils or synthetic oils with aniline points of 85°C or higher have problems in that they are poorly emulsifiable and unstable.

[0007] The present invention has been made in consideration of the current state of the prior art described above, and a main object of the present invention is to provide a metalworking oil composition that suppresses metal elution and has excellent corrosion prevention properties, and a metalworking method using the metalworking oil composition. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems. As a result, they have found that a metalworking oil composition containing a mineral oil having an aniline point within a specific range can suppress the elution of copper into the metalworking oil composition or a dilution solution of the metalworking oil composition. The present invention has been completed based on this finding.

[0009] That is, a metal working oil composition according to one embodiment of the present invention includes an oil-in-water emulsion containing water and a mineral oil having an aniline point of 60°C to 84°C, and the average oil droplet size of the emulsion is 90 nm to 350 nm. The aniline point is the minimum temperature at which equal volumes of aniline and a hydrocarbon or a mixture of hydrocarbons exist as a homogeneous solution, and is a value measured according to JIS K2256.

[0010] In the above-mentioned metal working oil composition, the mineral oil may include a paraffinic mineral oil having a sulfur content of 0.2 wt % or less.

[0011] The metalworking oil composition may contain a naphthenic mineral oil having an elemental sulfur content of 0.07% by weight or less.

[0012] A metalworking method according to one aspect of the present invention involves working a metal material using any one of the metalworking oil compositions described above.

[0013] In the above-mentioned metal processing method, the metal material may be a copper-based metal material or a zinc-based metal material. Effect of the Invention

[0014] According to the present invention, it is possible to provide a metalworking oil composition which inhibits metal elution and has excellent corrosion prevention properties, and a metalworking method using this metalworking oil composition. [Brief description of the drawings]

[0015] [Figure 1] 1 is a graph showing the relationship between the amount of copper eluted and the average oil droplet diameter. [Diagram 2] 1 is a graph showing the relationship between the amount of zinc dissolved and the average oil droplet diameter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described in detail.

[0017] In this specification, unless otherwise specified, the unit "%" for content or blend ratio means "% by weight".

[0018] 1. Metalworking oil composition The metal working oil composition according to the embodiment of the present invention comprises an oil-in-water emulsion containing a mineral oil having an aniline point of 60° C. or more and 84° C. or less, and water. The composition of the metal working oil composition according to the embodiment will be specifically described below.

[0019] The metalworking oil composition according to the embodiment contains a mineral oil having an aniline point of 60°C or more and 84°C or less as a base oil. Mineral oils are mixtures of hydrocarbons having various chemical structures, and are classified into paraffinic mineral oils, naphthenic mineral oils, and aromatic mineral oils depending on the main component hydrocarbons. In the present invention, it is preferable to use paraffinic mineral oils and naphthenic mineral oils, and it is more preferable to use paraffinic mineral oils. The mineral oils may be used alone or in combination of two or more types.

[0020] The content of the base oil in the metal working oil composition according to the embodiment is preferably, for example, 40% or more and 85% or less of the total amount of the base oil based on the total amount of the metal working oil composition. In this case, the elution of metal is more effectively suppressed, the corrosion prevention is improved, and the stability of the metal working oil composition is improved. The lower limit of the total amount of the base oil is more preferably 45%, and further preferably 50%. The upper limit of the total amount of the base oil is more preferably 80%, and further preferably 75%.

[0021] The metalworking oil composition according to the embodiment may appropriately contain other base oils within the scope of the present invention. The other base oils may be either natural or synthetic, for example, vegetable oils, fatty acid esters, etc. In addition to the base oil, the metalworking oil composition may further contain, for example, fatty acids, fatty acid condensation products, etc. as oil components.

[0022] When the metal working oil composition contains oil components other than the base oil, from the viewpoint of further enhancing the effects of the present invention, the content of the base oil is preferably 0.6 parts by mass or more in total per 1 part by mass of the total amount of the oil components, more preferably 0.7 parts by mass or more, and even more preferably 0.8 parts by mass or more.

[0023] The mineral oil contained in the metalworking oil composition according to the embodiment satisfies the condition that the aniline point is 60°C or more and 84°C or less, as described above. When the aniline point of the mineral oil is within the above range, the effect of suppressing the elution of metal (workpiece) into the metalworking oil composition or a dilution solution of the metalworking oil composition is significantly exhibited, and an excellent anticorrosive effect can be exhibited, and further, discoloration of the metalworking oil composition can be prevented, and the emulsification and stability of the metalworking oil composition can be improved. The lower limit of the aniline point is preferably 65°C, 70°C, and 80°C, in that order. From the viewpoint of the emulsification and stability of the metalworking oil composition, when the mineral oil is a naphthenic mineral oil, the upper limit of the aniline point is preferably 70°C.

[0024] In the embodiment, it is preferable that the amount of impurities contained in the mineral oil is small, that is, the purity of the mineral oil is high. The amount of impurities contained in the mineral oil can be appropriately set according to the type of mineral oil, but for example, when the mineral oil is a paraffin-based mineral oil, the content of sulfur element, which is the main impurity, is preferably 0.2% or less based on the total amount of the paraffin-based mineral oil. In this case, the amount of impurities such as sulfur element can be reduced, and the elution of metals can be effectively suppressed. The content of sulfur element in the paraffin-based mineral oil is more preferably 0.18% or less, and even more preferably 0.16% or less.

[0025] For example, when the mineral oil is naphthenic mineral oil, the content of elemental sulfur, which is the main impurity, is preferably 0.07% or less of elemental sulfur based on the total amount of naphthenic mineral oil. In this case, the amount of impurities such as elemental sulfur can be reduced, and the elution of metals can be effectively suppressed. The content of elemental sulfur in paraffinic mineral oil is more preferably 0.05% or less. and more preferably 0%.

[0026] In this specification, impurities such as elemental sulfur in mineral oil can be measured by X-ray fluorescence analysis (XRF), inductively coupled plasma (ICP) emission spectrometry, or the like.

[0027] The metalworking oil composition according to the embodiment contains water. The water used may be tap water, industrial water, ion-exchanged water, distilled water, or the like, and may be hard water or soft water. The content of water in the metalworking oil composition of the present invention may generally be 1% or more and 5% or less based on the total amount of the metalworking oil composition.

[0028] The metalworking oil composition according to the embodiment preferably further contains a surfactant. The surfactant may be a nonionic surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or the like. Among them, it is preferable to use a nonionic surfactant from the viewpoint of dispersibility. The surfactant may be used alone or in any combination of two or more kinds.

[0029] Examples of nonionic surfactants include glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxysorbitol fatty acid esters, polyoxyalkylene ethers, polyoxyalkylene alkyl ethers, etc. Among them, polyoxyalkylene alkyl ethers are preferred. Examples of polyoxyalkylene alkyl ethers include polyoxyalkylene oleyl ethers, polyoxyalkylene oleyl cetyl ethers, polyoxyalkylene lauryl ethers, etc. Examples of polyoxyalkylene oleyl ethers include polyoxyethylene oleyl ethers. Examples of polyoxyalkylene lauryl ethers include polyoxyethylene lauryl ethers.

[0030] The content of the surfactant in the metalworking oil composition can be appropriately set depending on the type of surfactant, the type and content of other blended components, etc. For example, the content of the surfactant is preferably set to 0.01% or more and 9.0% or less of the total amount of the surfactant based on the total amount of the metalworking oil composition. In this case, the oil droplet size can be adjusted within an appropriate range, the emulsion stability of the metalworking oil composition can be improved, and the elution of metal can be effectively suppressed.

[0031] The metal working oil composition according to the embodiment can be obtained by mixing and stirring the base oil containing the mineral oil, water, and a surfactant to prepare an oil-in-water emulsion.

[0032] The metal working oil composition according to the embodiment may contain various additives, such as an antioxidant, a rust inhibitor, a corrosion inhibitor, a preservative, an antifoaming agent, and an extreme pressure additive, as necessary.

[0033] Examples of the antioxidant include amine-based antioxidants, phenol-based antioxidants, zinc dialkyldithiophosphate, zinc diallyldithiophosphate, organic sulfides, etc. The antioxidants may be used alone or in combination of two or more. When an antioxidant is contained, the total amount of the antioxidant may be generally 1% or more and 10% or less based on the total amount of the metalworking oil composition.

[0034] Examples of the rust inhibitor include organic amines, aliphatic monocarboxylic acids and dicarboxylic acids having 6 to 36 carbon atoms and their amides, alkenyl succinic acids having 6 to 36 carbon atoms and their amides, aromatic carboxylic acids, benzotriazoles, etc. The rust inhibitors may be used alone or in combination of two or more. When a rust inhibitor is contained, the total amount of the rust inhibitor may be generally 0.01% or more and 3% or less based on the total amount of the metalworking oil composition.

[0035] Examples of the corrosion inhibitor include phosphoric acid ester, alkylphosphonic acid, sodium metasilicate, etc. The corrosion inhibitor may be used alone or in combination of two or more. When the corrosion inhibitor is contained, the content of the corrosion inhibitor may be generally 1% or more and 5% or less based on the total amount of the metalworking oil composition.

[0036] Examples of the preservative include triazine compounds, thiazoline compounds, and phenol compounds. The preservative may be used alone or in combination of two or more. When the preservative is contained, the total amount of the preservative may be generally 0.001% or more and 3% or less based on the total amount of the metalworking oil composition.

[0037] The antifoaming agent may be a polyorganosiloxane having a molecular weight of 100 to 1,000. The antifoaming agent may be used alone or in combination of two or more. When the antifoaming agent is contained, the total amount of the antifoaming agent may be generally 0.001% or more and 1% or less based on the total amount of the metalworking oil composition.

[0038] Examples of the extreme pressure additive include sulfur compounds such as lead soap and sulfurized fatty acids, chlorine compounds such as chlorinated paraffin, phosphorus compounds, etc. The extreme pressure additive may be used alone or in combination of two or more kinds.

[0039] The metalworking oil composition according to the embodiment is water-soluble and can be used as is for processing metal materials. The metalworking oil composition according to the embodiment can also be used as a stock solution and further diluted with a diluent such as water to form a coolant for processing metal materials.

[0040] When the metalworking oil composition according to the embodiment is diluted with a diluent for use, the dilution ratio may be appropriately adjusted according to the composition of the metalworking oil composition and the performance required during metalworking. When the metalworking oil composition is diluted for use, it is usually diluted 1.5 times or more and 100 times or less. From the viewpoint of further enhancing the effects of the present invention and improving the processing characteristics, the dilution ratio is preferably 5 times or more and 50 times or less, more preferably 10 times or more and 30 times or less.

[0041] The pH of the metalworking oil composition of the present invention during use is preferably 8.0 to 9.0, more preferably 8.2 to 8.9. When the pH of the water-diluted solution of the metalworking oil composition is within the above range, the metal elution-inhibiting effect is excellent, the corrosion prevention properties are improved, and the water-diluted solution is effectively prevented from spoiling.

[0042] The average oil droplet diameter of the metalworking oil composition according to the embodiment is preferably 90 nm or more and 350 nm or less. When the average oil droplet diameter of the metalworking oil composition is within the above range, the effect of suppressing the elution of metal (workpiece) into the metalworking oil composition or a dilution of the metalworking oil composition is exhibited, and the stability of the oily component is improved.

[0043] The metalworking oil composition according to the embodiment can be used for machining, such as cutting, grinding, polishing, and cutting of metal materials. Examples of the metal to be machined include non-ferrous metals and alloys thereof, such as Inconel, titanium, titanium alloys, aluminum, aluminum alloys, magnesium, magnesium alloys, copper, and copper alloys. In particular, when the metalworking oil composition of the present invention is applied to copper-based metals, zinc-based metals, and alloys thereof, such as brass, which are easily corroded and have low corrosion prevention effects by conventional corrosion inhibitors and rust inhibitors, the metal elution suppression effect is satisfactorily exhibited.

[0044] 2.Metal processing method In the metal processing method according to the embodiment of the present invention, a metal material is processed using the metal processing oil composition according to the embodiment. Examples of the processing of the metal material include cutting, grinding, polishing, and cutting. When the metalworking oil composition is supplied to a machining point in the form of, for example, a liquid or mist, it exhibits an effect of inhibiting the elution of metal materials into the metalworking oil composition, and can improve corrosion prevention.

[0045] Examples of the types of metals to be processed include the above-mentioned metals, etc. In particular, when the metal processing method of the present invention is applied to copper-based metals, zinc-based metals, and alloys thereof, such as brass, which are easily corroded and have low corrosion prevention effects by conventional anticorrosives and rust inhibitors, the metal elution suppression effect is satisfactorily exhibited, which is preferable. EXAMPLES

[0046] The present invention will now be described in more detail with reference to examples and comparative examples, but it is not intended that the present invention be limited to these examples.

[0047] [Example 1] <Preparation of Metal Working Oil Composition> The mineral oil used was mineral oil A (naphthenic mineral oil) whose physical properties are shown in Table 1 below. The composition of the mineral oil was analyzed using an X-ray fluorescence analyzer (EDX-8100, manufactured by Shimadzu Corporation). The analysis results are also shown in Table 1. Specifically, the contents of the main impurities, S, Ag, and Hf, were analyzed, and the contents of these impurities were subtracted to calculate the remainder as resin.

[0048] [Table 1]

[0049] According to the composition shown in Table 2 below and the surfactant composition shown in Table 3 below, a metalworking oil composition of Example 1 was prepared. The surfactants shown in Table 3 are as follows: Surfactant A: Polyoxyalkylene lauryl ether Surfactant B: Polyoxyalkylene oleyl cetyl ether Surfactant C: Polyoxyethylene oleyl ether Surfactant D: Polyoxyalkylene lauryl ether There was no particular limitation on the method for preparing the metalworking oil composition, and the metalworking oil composition was prepared by sequentially adding each component at room temperature and appropriately stirring using a general stirring method.

[0050] [Table 2]

[0051] [Table 3]

[0052] [Examples 2 to 4] Metalworking oil compositions of Examples 2 to 4 were prepared in the same manner as in Example 1, except that the blending ratios of the surfactants were as shown in Table 3.

[0053] [Examples 5 to 8] The metalworking oil compositions of Examples 5 to 8 were prepared in the same manner as in Example 1, except that mineral oil B (paraffinic mineral oil) shown in Table 1 above was used as the mineral oil and the blending ratio of the surfactant was as shown in Table 3.

[0054] [Comparative Examples 1 to 4] The metalworking oil compositions of Comparative Examples 1 to 4 were prepared in the same manner as in Example 1, except that mineral oil C (naphthenic mineral oil) shown in Table 1 above was used as the mineral oil and the blending ratio of the surfactant was as shown in Table 3.

[0055] <Oil droplet size measurement> The average oil droplet size of the metalworking oil composition was measured for each test solution after preparation. The average oil droplet size was measured using a particle size measuring device ("ELSZ-1000" (manufactured by Otsuka Electronics Co., Ltd.)) using dynamic light scattering (photon correlation method). The measurement results of Examples 1 to 8 and Comparative Examples 1 to 4 are shown in Table 3 above.

[0056] <Metal elution inhibition test> The test solution was prepared by diluting the sample stock solution in Table 2 above with water to 5% and adjusting the pH to about 8.85. 5 g of brass grinding powder was added to 20 g of each of the water-diluted solutions in the above Examples and Comparative Examples, and the solution was left to stand at 50°C for one week. The solution was then filtered using filter paper, and the copper and zinc concentrations in the filtrate were measured using an atomic absorption spectrophotometer. The copper and zinc concentrations (mg / L) in the filtrate were taken as the amounts of copper and zinc eluted (mg / L), respectively. The amount of elution was measured using an atomic absorption spectrophotometer ("AA240FS" (manufactured by Agilent Technologies)) using the atomic absorption method. The test results for Examples 1 to 8 and Comparative Examples 1 to 4 are shown in Table 4 below. Figures 1 and 2 are created based on Tables 3 and 4. Figure 1 is a graph showing the relationship between the amount of copper eluted and the average oil droplet diameter. The vertical axis of Figure 1 shows the amount of copper eluted (unit: mg / L), and the horizontal axis shows the average oil droplet diameter (unit: nm). Figure 2 is a graph showing the relationship between the amount of zinc eluted and the average oil droplet diameter. The vertical axis of Figure 2 shows the amount of zinc eluted (unit: mg / L), and the horizontal axis shows the average oil droplet diameter (unit: nm).

[0057] [Table 4]

[0058] As is clear from the above Table 4 and Figures 1 and 2, the amounts of copper and zinc eluted into the diluted solution of the metalworking oil composition are reduced in the test solutions of Examples 1 to 8, in which the aniline point of the mineral oil in the metalworking oil composition is within the range of 60° C. or higher and 84° C. or lower. In contrast, the effect of inhibiting the elution of copper and zinc is not sufficiently obtained in the test solutions of Comparative Examples 1 to 4, in which the aniline point of the mineral oil in the metalworking oil composition is outside the range of 60° C. or higher and 84° C. or lower.

[0059] As is clear from Figures 1 and 2, as the average oil droplet size increases, the amount of copper and zinc eluted decreases. When comparing oils with similar average oil droplet sizes, the amount of copper and zinc eluted decreases in the order of mineral oil C, mineral oil A, and mineral oil B. This shows that paraffinic mineral oils are more effective at suppressing the elution of metals than naphthenic mineral oils, and that for the same type of naphthenic mineral oil, oils with higher aniline points are more effective at suppressing the elution of metals. The lower limit of the aniline point of mineral oils is preferably 65°C, 70°C, and 80°C, in that order. In the case of naphthenic mineral oils, the aniline point is preferably 70°C or less.

[0060] In addition, the amounts of copper and zinc eluted were smaller when mineral oil A was used than when mineral oil C was used, which shows that the elution of metals can be effectively suppressed by reducing the impurities in the same type of naphthenic mineral oil. The sulfur content in naphthenic mineral oil is preferably 0.07% by weight or less. In addition, the elution of metals was effectively suppressed in mineral oil B, so the sulfur content in paraffinic mineral oil is preferably 0.2% by weight or less.

[0061] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims.

Claims

1. A metalworking oil composition comprising an oil-in-water emulsion containing water and a mineral oil having an aniline point of 60° C. or more and 84° C. or less, wherein the average oil droplet size of the emulsion is 90 nm or more and 350 nm or less.

2. The metalworking oil composition according to claim 1, further comprising a nonionic surfactant.

3. 3. The metal working oil composition according to claim 1, wherein the mineral oil comprises a paraffinic mineral oil having a sulfur content of 0.2% by weight or less or a naphthenic mineral oil having a sulfur content of 0.07% by weight or less.

4. A metalworking method comprising the step of working a metal material by using the metalworking oil composition according to any one of claims 1 to 3.

5. 5. The method for processing metals according to claim 4, wherein the metal material is a copper-based metal material or a zinc-based metal material.

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