Aqueous composition, method for producing stainless steel using same, and thin film processing method

Abstract

The invention provides an aqueous composition capable of manufacturing stainless steel with a thin film, the stainless steel and a manufacturing method thereof, a stainless steel thin film processing method and the like. The above-mentioned problem is solved by using an aqueous composition for thinning stainless steel, the aqueous composition containing 0.01-10% by mass of hydrogen peroxide, 12.5-40% by mass of halide ions, and 0-3.0% by mass of copper ions. According to the present invention, stainless steel can be thinned by a simple method.

Description

Technical Field

[0001] The present invention relates to an aqueous composition, a method for producing stainless steel using the aqueous composition, and a method for thinning stainless steel, and more particularly to an aqueous composition for thinning stainless steel. Background Art

[0002] Stainless steel has been studied in recent years for its excellent durability and weather resistance in various fields. For example, stainless steel is increasingly being used in electronic parts, battery collector foils, and automobile parts housings.

[0003] When stainless steel is used in various products, it is known that treatment for increasing the surface area (for example, Patent Document 1) or treatment for forming irregularities on the surface of the stainless steel (for example, Patent Document 2) is performed.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-168017

[0007] Patent Document 2: Japanese Patent Application Publication No. 2015-183239 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] Depending on the application of stainless steel, it is desirable to reduce the thickness of the stainless steel, and in particular, it is sometimes required to reduce the thickness of the stainless steel while maintaining the smoothness of the surface. In addition, it is difficult to obtain stainless steel with sufficiently suppressed surface roughness and reduced thickness by conventional stainless steel manufacturing methods or surface treatment methods.

[0010] Solutions for solving problems

[0011] The present invention provides the following aqueous composition, method for producing stainless steel, method for thin-film treatment of stainless steel, etc.

[0012] That is, the present invention includes the following contents.

[0013] [1] An aqueous composition for thinning stainless steel, the aqueous composition comprising 0.01 to 10% by mass of hydrogen peroxide, 12.5 to 40% by mass of halide ions, and 0 to 3.0% by mass of copper ions.

[0014] [2] The aqueous composition according to [1] above, comprising 0.1 to 5% by mass of hydrogen peroxide, 15 to 30% by mass of halide ions, and 0 to 1.0% by mass of copper ions.

[0015] [3] A method for producing stainless steel, comprising a step of thinning the stainless steel using the aqueous composition according to [1] or [2] above.

[0016] [4] The method for producing stainless steel according to [3] above, wherein the average roughness (Ra) of the stainless steel surface after the thin-film treatment is 0.35 μm or less and the maximum height (Rz) is 2.5 μm or less.

[0017] [5] The method for producing stainless steel according to [3] or [4] above, wherein the density of the stainless steel after the film forming treatment is 4.5 g / cm 3 above.

[0018] [6] The method for producing stainless steel according to any one of [3] to [5] above, wherein the density (g / cm 3 ) is the density of the stainless steel before filming (g / cm 3 ) is more than 0.60 times.

[0019] [7] The method for producing stainless steel according to any one of [3] to [6] above, wherein the thickness of the stainless steel after the thin-film treatment is 100 μm or less.

[0020] [8] The method for producing stainless steel according to any one of [3] to [7] above, wherein the thickness (μm) of the stainless steel after the thin-film treatment is not more than 0.95 times the thickness (μm) of the stainless steel before the thin-film treatment.

[0021] [9] A method for thinning stainless steel, comprising a thinning step of thinning the stainless steel using the aqueous composition described in [1].

[0022] Effects of the Invention

[0023] According to the present invention, an aqueous composition capable of thinning stainless steel by a simple method, a method for manufacturing stainless steel having such a thin-filming treatment step, and a thin-filming treatment method are provided. According to the present invention, the roughness of the surface of stainless steel in a foil or plate form can be suppressed and thin-filming can be achieved. DETAILED DESCRIPTION

[0024] Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following contents, and various modifications can be made without departing from the gist of the present invention.

[0025] [1. Aqueous composition]

[0026] The aqueous composition of the present invention is used to thin stainless steel, and contains 0.01 to 10% by mass of hydrogen peroxide, 12.5 to 40% by mass of halide ions, and 0 to 3.0% by mass of copper ions, based on the total amount of the aqueous composition. In addition to these components, the aqueous composition of the present invention may also contain water, particularly ion-exchanged water or ultrapure water.

[0027] Hereinafter, each component of the aqueous composition will be described.

[0028] (1-1. Hydrogen peroxide)

[0029] The concentration of hydrogen peroxide in the aqueous composition is 0.01 to 10% by mass, preferably 0.05 to 7% by mass, 0.1 to 5% by mass or 0.15 to 7% by mass, more preferably 0.2 to 3% by mass or 0.3 to 4% by mass, further preferably 0.3 to 2% by mass or 0.4 to 1.5% by mass, and particularly preferably 0.5 to 1% by mass, based on the total amount (total mass) of the aqueous composition.

[0030] In addition, the lower limit of the concentration of hydrogen peroxide in the aqueous composition may be, for example, 0.001 mass%, 0.01 mass%, 0.05 mass%, 0.10 mass%, 0.15 mass%, 0.2 mass%, 0.25 mass%, 0.3 mass%, 0.35 mass%, 0.4 mass%, or 0.45 mass%, based on the total amount (total mass) of the aqueous composition, and the upper limit of the concentration of hydrogen peroxide contained in the aqueous composition may be, for example, 9 mass%, 8 mass%, 7 mass%, 6 mass%, 5 mass%, 4 mass%, 4.0 mass%, 3.5 mass%, 3 mass%, 3.0 mass%, 2.5 mass%, 2 mass%, 2.0 mass, 1.5 mass%, 1 mass%, or 1.0 mass%, based on the total amount (total mass) of the aqueous composition.

[0031] The concentration range of hydrogen peroxide can be selected from a range obtained by appropriately combining the above lower limit value and upper limit value.

[0032] By setting the concentration of hydrogen peroxide within the above range, the effects of the present invention tend to be more appropriately achieved, and even if copper ions, halide ions, etc. described later coexist in the aqueous composition, the possibility of heat generation or foaming associated with the decomposition of hydrogen peroxide can be suppressed, thereby ensuring work safety.

[0033] (1-2. Halide ions (halogen ions))

[0034] The type of halide ion contained in the aqueous composition is not particularly limited, and may be, for example, fluoride ion, chloride ion, bromide ion, or iodide ion. From the viewpoint of ease of handling and economic efficiency, chloride ion is more preferred.

[0035] The halogen compound providing halide ions is not particularly limited, and examples thereof include hydrochloric acid, alkali metal halides such as sodium halide and potassium halide, alkaline earth metal halides such as calcium halide, ammonium halide, copper halide, and hydrogen halide. Among them, hydrochloric acid, alkali metal halide or hydrogen halide is preferred, and hydrochloric acid or sodium chloride is more preferred, from the viewpoint of more effectively and reliably exerting the effects of the present invention.

[0036] The halogen compound can be used alone or in combination of two or more. It should be noted that the halogen compound can be repeated with the following copper compound. For example, when a copper halide is used as a source of halide ions, the copper halide is also equivalent to a copper compound as a source of copper ions. As the copper halide, copper chloride is preferred. It can be considered that the halogen compound (halide ion) causes pitting of the passivation film during the thin film treatment of the stainless steel surface.

[0037] The concentration of halide ions in the aqueous composition is 12.5 to 30% by mass, preferably 13 to 28% by mass, 14 to 29% by mass, or 15 to 30% by mass, more preferably 16 to 26% by mass, or 17 to 27% by mass, and particularly preferably 18 to 25% by mass, 19 to 26% by mass, or 20 to 25% by mass, based on the total amount (total mass) of the aqueous composition.

[0038] In addition, the lower limit of the concentration of halide ions in the aqueous composition may be any of 8 mass%, 10 mass%, 12 mass%, 14 mass%, 15 mass%, 16 mass%, 17 mass%, 18 mass%, 19 mass% and 20 mass%, based on the total amount of the aqueous composition (total mass), and the upper limit of the concentration of halide ions may be any of 30 mass%, 29 mass%, 28 mass%, 27 mass%, 26 mass% and 25 mass%, based on the total amount of the aqueous composition.

[0039] The concentration range of the halide ions can be appropriately selected from a range obtained by appropriately combining the above lower limit value and upper limit value.

[0040] By setting the concentration of halide ions within the above range, there is a tendency that the effects of the present invention can be more appropriately achieved. More specifically, in an aqueous composition having a halide ion concentration within the above range, the pitting reaction of stainless steel can be prevented from proceeding, a thin film can be achieved, and the decomposition reaction of hydrogen peroxide can be prevented to ensure safety.

[0041] (1-3. Copper ions)

[0042] The concentration of copper ions in the aqueous composition is 0 to 3% by mass based on the total amount (overall mass) of the aqueous composition. That is, the aqueous composition of the present invention does not contain copper ions or the content of copper ions is less than 3% by mass based on the total amount (overall mass) of the aqueous composition. The copper ions in the aqueous composition can be produced by mixing the copper compound as a copper ion source with other components. Regarding the type of copper ion source, as long as it is a copper compound that can supply copper ions in the aqueous composition, there is no particular limitation.

[0043] For example, it can be an anhydrous substance or a pentahydrate, and copper sulfates such as copper sulfate (II), copper chlorides such as copper chloride (II), copper tetrafluoroborate, copper bromide (II), copper oxide (II), copper phosphates, copper acetates, copper formates, copper nitrates, etc. can be enumerated. Among them, from the viewpoint of more effectively and reliably playing the effect of the present invention, ease of operation, and economy, preferred copper sulfates or copper chlorides, more preferably copper sulfate (II) or copper chloride (II), further preferred copper sulfate (II). They can be used alone or in combination of more than two.

[0044] It is presumed that copper ions contained in the aqueous composition cause a substitution reaction with nickel and chromium, which are components of the stainless steel, during the film forming treatment, and that a suitable roughened shape is obtained by subsequently removing the substitution reaction product derived from the copper ions.

[0045] In order to improve the quality of stainless steel after thinning, and in particular, to prevent the generation of extremely thin regions and pinholes in the aqueous composition used for treating thin stainless steel foil as described below, it is preferred to adjust the content of copper ions.

[0046] The concentration of copper ions contained in the aqueous composition is 3% by mass or less, preferably 2% by mass or less, less than 1.5% by mass or less, more preferably 1.2% by mass or less or 1.0% by mass, and may be 0.75% by mass or less, 0.5% by mass or less, or less than 0.25% by mass. The concentration range of copper ions is 0 to 3% by mass, preferably 0 to 2% by mass or 0 to 1.5% by mass, more preferably 0 to 1.5% by mass or 0.1 to 1.2% by mass, further preferably 0.2 to 1.0% by mass, and may be 0.3 to 1.5% by mass.

[0047] The lower limit of the concentration of copper ions in the aqueous composition is 0% by mass based on the total amount (total mass) of the aqueous composition, but may be, for example, 0.00001% by mass (0.1 ppm by mass), 0.0001% by mass (1 ppm by mass), 0.001% by mass, 0.01% by mass, 0.02% by mass, 0.03% by mass, 0.05% by mass, 0.07% by mass, or 0.1% by mass.

[0048] In addition, the upper limit of the copper ion concentration in the aqueous composition is based on the total amount of the aqueous composition, for example, 3 mass%, 2.5 mass%, 2 mass%, 1.7 mass%, 1.5 mass%, 1 mass%, 0.5 mass%, 0.3 mass%, 0.22 mass%, 0.16 mass%, 0.14 mass%, etc. The range of the copper ion concentration can be selected from the range formed by appropriately combining the above-mentioned lower limit and upper limit, for example, it can be appropriately selected from 0.0001-3 mass%, 0.001-3 mass%, 0.01-2 mass%, 0.01-1.7 mass%, 0.01-1.5 mass%, 0.02-1 mass%, 0.03-0.25 mass%, 0.03-0.20 mass%, 0.05-0.15 mass%, 0.05-0.12 mass%, etc.

[0049] When the concentration of copper ions is within the above range, the effects of the present invention tend to be more appropriately achieved.

[0050] On the other hand, when the copper ion concentration in the aqueous composition is too high, pinholes or extremely thin regions are likely to form in the stainless steel after the film-forming treatment, while when the copper ion concentration is too low, the film-forming treatment may not be performed efficiently.

[0051] (1-4. Additives contained in aqueous composition)

[0052] The aqueous composition of the present invention may further contain additives as components other than the above-mentioned hydrogen peroxide, copper ions and halide ions within the scope of exerting the effects of the present invention. As additives, for example, heterocyclic nitrogen compounds (azole compounds), organic solvents, etc. may be cited. These may be used alone or in combination of two or more. In addition, surfactants, pH adjusters, etc. may also be cited as additives, but these are preferably not included in the aqueous composition of the present invention.

[0053] The concentration of the additives that may be contained in the aqueous composition is preferably 10% by mass or less, more preferably 5.0% by mass or less, more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less.

[0054] (1-5. Water)

[0055] The aqueous composition of the present invention may contain water, preferably water. The water is not particularly limited, and preferably water obtained by removing metal ions, organic impurities, particles, etc. by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., more preferably pure water, and particularly preferably ultrapure water.

[0056] The content of water in the aqueous composition of the present invention is the remainder of the above-mentioned components and additives described in detail later, and is not particularly limited. It is preferably 50 to 98% by mass, more preferably 60 to 95% by mass, further preferably 75 to 93% by mass, and particularly preferably 85 to 90% by mass, based on the total amount (total mass) of the aqueous composition.

[0057] The aqueous composition of the present invention is preferably a dissolving liquid, and preferably does not contain components that are insoluble in the composition as a dissolving liquid, for example, solid particles such as abrasive particles.

[0058] (1-6. Functions and properties of aqueous composition)

[0059] It is considered that the aqueous composition containing the above-mentioned components suppresses an extreme increase in the roughness of the stainless steel surface, that is, suppresses the generation of significant irregularities, and efficiently reduces the thickness of the stainless steel surface as described below.

[0060] The halide ions play a role in pitting the oxide film usually formed on the surface of stainless steel. It is believed that, as described above, the copper ions have a role in substitution reaction with nickel and chromium as stainless steel components, and then the substitution reaction products from the copper ions are removed, forming some unevenness on the surface of the stainless steel and thinning it.

[0061] In addition, hydrogen peroxide plays a role in removing the substitution reaction product derived from copper ions after the above-mentioned substitution reaction.

[0062] Furthermore, by using an aqueous composition containing copper ions and the like whose content is adjusted to an appropriate range, it is possible to prevent the generation of extremely thin regions and pinholes in stainless steel, particularly stainless steel foil, after being subjected to a film-reducing treatment.

[0063] The aqueous composition of the present invention is prepared by adding the above-mentioned hydrogen peroxide-containing component, halide ion supplying component, water, and, if necessary, a copper ion supplying component and other components, and stirring until the mixture is uniform.

[0064] The properties of the aqueous composition are not particularly limited, but the pH is preferably -1.0 to 4.0, more preferably -0.5 to 3.0, further preferably -0.25 to 2.5, particularly preferably -0.1 to 2.0, 0.0 to 1.5, 0.005 to 1.0, or 0.01 to 0.5. The pH can be measured by the method described in Examples.

[0065] [2. Method for manufacturing stainless steel]

[0066] The method for producing stainless steel of the present invention includes a step of thinning the stainless steel using the aqueous composition. According to the method for producing stainless steel of the present invention, the surface smoothness of stainless steel in a plate or foil shape can be substantially maintained while thinning the stainless steel, i.e., reducing the thickness.

[0067] (2-1. Surface roughness of stainless steel)

[0068] According to the method for manufacturing stainless steel of the present invention, the arithmetic mean roughness (Ra) of the surface of stainless steel (stainless steel foil (film or sheet) is also included in stainless steel) after thin film treatment can be suppressed to below 0.35 μm. That is, in the surface treatment of stainless steel, the surface roughness increases in many cases, but in the method for manufacturing stainless steel of the present invention, the value of the arithmetic mean roughness (Ra) of the treated surface can be suppressed to below 0.35 μm. Preferably, the value of the arithmetic mean roughness (Ra) of the surface of stainless steel after thin film treatment is below 0.34 μm, below 0.33 μm, below 0.32 μm, below 0.31 μm, below 0.30 μm, below 0.29 μm or below 0.28 μm, more preferably below 0.27 μm or below 0.26 μm, and particularly preferably below 0.25 μm, below 0.24 μm or below 0.23 μm. In addition, the value of the arithmetic mean roughness (Ra) of the stainless steel surface after the thin-filming treatment may be 0.4 μm or less, 0.5 μm or less, or 0.6 μm or less.

[0069] The lower limit of the arithmetic mean roughness (Ra) of the stainless steel surface after the thin-filming treatment is not particularly limited, and is, for example, 0.03 μm or more, 0.05 μm or more, or 0.07 μm or more.

[0070] The arithmetic mean roughness (Ra) of the untreated stainless steel is not particularly limited, and is, for example, 0.02 to 0.15 μm or 0.03 to 0.10 μm, and preferably 0.04 to 0.08 μm.

[0071] In the method for thin-filming of stainless steel of the present invention, the increase (A1-A2 (μm)) of the arithmetic mean roughness (Ra) value A1 of the stainless steel surface after the thin-filming treatment relative to the arithmetic mean roughness (Ra) value A2 of the untreated stainless steel surface can be 0.3 μm or less, preferably the increase in Ra is 0.27 μm or less or 0.25 μm or less, more preferably the increase in Ra is 0.23 μm or less or 0.20 μm or less, and particularly preferably the increase in Ra is 0.18 μm or less or 0.16 μm or less.

[0072] The thin film treatment method of stainless steel of the present invention can suppress the maximum height (Rz) of the stainless steel surface after the thin film treatment to less than 2.5μm. That is, in the surface treatment of stainless steel, the surface roughness increases in many cases, but in the stainless steel manufacturing method of the present invention, the value of the maximum height (Rz) of the treated surface can be suppressed to less than 2.5μm. Preferably, the value of the maximum height (Rz) of the stainless steel surface after the thin film treatment is less than 2.4μm, less than 2.3μm, less than 2.2μm, less than 2.1μm, less than 2.0μm, less than 1.9μm or less than 1.8μm, more preferably less than 1.7μm or less than 1.6μm, particularly preferably less than 1.5μm, less than 1.4μm or less than 1.3μm. In addition, the value of the maximum height (Rz) of the stainless steel surface after the thin film treatment can also be less than 3.0μm, less than 3.5μm or less than 4.0μm.

[0073] The lower limit of the maximum height (Rz) of the stainless steel surface after the thinning treatment is not particularly limited, and may be, for example, 0.6 μm or more, 0.8 μm or more, or 1.0 μm or more.

[0074] The maximum height (Rz) of the untreated stainless steel is not particularly limited, and is, for example, 0.2 to 1.8 μm or 0.3 to 1.6 μm, and preferably 0.35 to 1.3 μm.

[0075] In the method for thinning stainless steel of the present invention, the increase (Z1-Z2 (μm)) of the maximum height (Rz) value Z1 of the stainless steel surface after the thinning treatment relative to the maximum height (Rz) value Z2 of the untreated stainless steel surface can be 2.2 μm or less, preferably the value of the increase in Rz is 1.8 μm or less or 1.7 μm or less, more preferably the value of the increase in Rz is 1.6 μm or less or 1.5 μm or less, and particularly preferably the value of the increase in Rz is 1.4 μm or less, 1.3 μm or less, 1.2 μm or less, 1.1 μm or less or 1.0 μm or less.

[0076] The arithmetic mean roughness (Ra) and the maximum height (Rz) are calculated in accordance with JIS B 0601-2001. The device used for the measurement is not particularly limited, and for example, a laser microscope can be used.

[0077] It should be noted that, after removing the precipitates from the surface of the stainless steel after the filming treatment by physical means such as adhesive tape, the arithmetic mean roughness (Ra) and the maximum height (Rz) values ​​after the filming treatment can be measured. However, such physical means may not be practical as part of the manufacturing process.

[0078] (2-2. Density of stainless steel)

[0079] The density of the stainless steel after the film forming process, i.e., the stainless steel after the film forming process, is preferably 4.5 g / cm 3 Although it is confirmed that the density of stainless steel tends to decrease due to the action of the aqueous composition, the film-forming treatment step can also prevent an extreme decrease in density. The density of stainless steel after the film-forming treatment is more preferably 5.0 g / cm 3 Above, 5.3g / cm 3 Above or 5.5g / cm 3 More preferably 5.6 g / cm 3 Above, 5.7g / cm 3 Above or 5.8g / cm 3 More preferably, 5.9 g / cm 3 Above, 6.0g / cm 3 Above or 6.1g / cm 3 Above, particularly preferably 6.2 g / cm 3 Above, 6.3g / cm 3 Above or 6.4g / cm 3 The density of stainless steel after film forming is not particularly limited, but is usually 7.3 g / cm 3 the following.

[0080] The density value D1 (g / cm 3 ) is preferably the density value D2 (g / cm2) of the stainless steel which is the same stainless steel and has not been subjected to the film forming treatment. 3 ), more preferably 0.65 times or more, 0.70 times or more, or 0.72 times or more, further preferably 0.74 times or more, 0.76 times or more, or 0.78 times or more, particularly preferably 0.80 times or more, 0.82 times or more, or 0.85 times or more. The ratio D1 / D2 of the density before and after the filming process is not particularly limited, but is usually 0.98 times or less.

[0081] The density value D1 (g / cm 3 ) is the same as the density value D2 (g / cm 3 ) difference, i.e. D2-D1(g / cm 3 ) is preferably 3.0 (g / cm 3 ) or less, more preferably 2.8 (g / cm 3 ) or less, 2.6(g / cm 3 ) or less than 2.4(g / cm 3) or less, more preferably 2.2 (g / cm 3 ) or less, 2.0(g / cm 3 ) or less than 1.8(g / cm 3 ) or less, particularly preferably 1.6 (g / cm 3 ) or less, 1.4(g / cm 3 ) or less than 1.2(g / cm 3 ) or less. The density difference before and after the filming process is D2-D1 (g / cm 3 ) is not particularly limited, but is usually 0.1 (g / cm 3 )above.

[0082] (2-3. Thickness of stainless steel)

[0083] The shape and thickness of the stainless steel to be treated as a thin film are not particularly limited, and foil-shaped or plate-shaped stainless steel is preferably used. When foil-shaped stainless steel, i.e., stainless steel foil, is treated as a thin film, the thickness is, for example, 100 μm or less, preferably 50 μm or less or 25 μm or less, more preferably 20 μm or less or 18 μm or less, further preferably 15 μm or less or 12 μm or less, and particularly preferably 10 μm or less. The lower limit of the thickness varies depending on the application and is not particularly limited, but is preferably 1 μm or more from the aspects of durability and weather resistance.

[0084] When plate-shaped stainless steel is subjected to the thin film treatment, the thickness is, for example, 2.0 mm or less, preferably 1.5 mm or less, more preferably 1.2 mm or less or less than 1.2 mm, further preferably 1.1 mm or less, less than 1.1 mm or 1.0 mm or less, and particularly preferably 0.8 mm or less. The lower limit of the thickness varies depending on the application and is not particularly limited, but is preferably 0.1 mm or more from the perspective of durability and weather resistance.

[0085] The thickness T1 (μm) of the stainless steel after the thin-film treatment is preferably 0.95 times or less (T1 / T2≤0.95) the thickness T2 (μm) of the stainless steel which is the same stainless steel and has not been subjected to the thin-film treatment, more preferably 0.9 times or less or 0.85 times or less, further preferably 0.8 times or less or 0.75 times or less, particularly preferably 0.7 times or less, 0.65 times or less or 0.6 times or less.

[0086] (2-4. Types of stainless steel)

[0087] The type of stainless steel to be treated to form a thin film using the aqueous composition of the present invention is not particularly limited, and examples thereof include the following stainless steels.

[0088] That is, chromium-nickel stainless steels specified by JIS G4305 standard, including SUS304, SUS316, SUS321, SUS347 and SUS329J1; ferritic stainless steels (chromium stainless steels) including SUS405, SUS430, SUS434, SUS444, SUS447 and SUSXM27; and precipitation hardening systems (chromium-nickel stainless steels) including SUS630, SUS631 and SUH660.

[0089] As the target of the thin-film treatment with the aqueous composition, among the above-mentioned stainless steels, SUS304, SUS430 series (SUS430 and SUS430LX, etc.), SUS444, etc. are more preferable.

[0090] (2-5. Aqueous composition)

[0091] In the method for manufacturing stainless steel, the above-mentioned aqueous composition is preferably used. That is, it is preferred to use an aqueous composition containing 0.1 to 5% by mass of hydrogen peroxide, 1 to 30% by mass of halide ions and 0 to 40% by mass of copper ions, all based on the total amount of the aqueous composition, in the thin film treatment step. The details of the components of the aqueous composition are as described above. Although fine concavoconvexities are formed on the surface of the stainless steel by the aqueous composition, significant roughening can be prevented, and the thickness of the stainless steel can be extremely reduced.

[0092] In the thin film treatment method for thinning the surface of stainless steel of the present invention, a thin film treatment step is performed. That is, the thin film treatment method of the present invention includes a thin film treatment step of thin film treatment of the surface of stainless steel using the above-mentioned aqueous composition. Here, thin film treatment of the surface of stainless steel using an aqueous composition means that the aqueous composition used in the treatment is brought into contact with the surface of stainless steel. It can also be seen from this that the thin film treatment method of stainless steel of the present invention at least includes a step of bringing the aqueous composition into contact with the surface of stainless steel.

[0093] (2-6. Thin-film forming conditions)

[0094] In the thin film forming step, the aqueous composition is brought into contact with the stainless steel to be treated.

[0095] In the thin film treatment step, the thin film treatment temperature is preferably 20 to 60° C., more preferably 25 to 55° C., and particularly preferably 30 to 50° C. Thus, the stainless steel surface can be thinned even at a room temperature of 25° C., for example, at a lower temperature. In this respect, the stainless steel thin film treatment method of the present invention is excellent. Here, the thin film treatment temperature refers to the temperature when the aqueous composition is brought into contact with the stainless steel surface, and particularly refers to the liquid temperature of the aqueous composition in contact with the stainless steel surface.

[0096] In addition, in the thin film treatment process, the thin film treatment time is preferably 30 seconds to 180 seconds, more preferably 40 seconds to 150 seconds, and particularly preferably 50 seconds to 130 seconds. In this way, the stainless steel can be thin-filmed even if it is not so long. In this regard, the thin film treatment method of stainless steel of the present invention is excellent. Here, the thin film treatment time refers to the time when the aqueous composition is brought into contact with the stainless steel surface. For example, it is the time when the stainless steel is immersed in the aqueous composition, and the time from when the aqueous composition is sprayed on the surface of the stainless steel to when the aqueous composition is removed by water or the like.

[0097] The method of bringing the aqueous composition into contact with the surface of stainless steel is not particularly limited, and for example, a method of bringing the aqueous composition into contact with stainless steel by dripping or spraying (spray treatment) or a method of immersing stainless steel in the aqueous composition can be adopted. In the present invention, any method can be adopted. For example, there can be cited: a method of spraying an aqueous composition onto stainless steel processed into a specific shape to obtain stainless steel after film treatment; a method of providing a dripping device, a spraying device or an immersion device for the aqueous composition between stainless steel foil rolls, and supplying the aqueous composition by passing through the vicinity of the above device while the stainless steel foil is unwound and moved from a roll formed by winding an untreated stainless steel foil, and winding up the stainless steel foil after film treatment to obtain a roll, etc.

[0098] The stainless steel subjected to the thin-film forming treatment in the thin-film forming treatment step may be subjected to a treatment such as water washing (cleaning step).

[0099] According to the above-mentioned method for thin-film treatment of stainless steel, stainless steel with suppressed surface irregularities and reduced thickness can be obtained by substantially only one-step treatment, that is, thin-film treatment in which the aqueous composition of the present invention is brought into contact with the surface of the stainless steel to be treated, or by only further appropriate cleaning (for example, water cleaning) as needed.

[0100] Furthermore, as described above, the thin-film forming treatment is performed under mild treatment conditions and in a short time. Therefore, according to the present invention, the thin-film forming treatment of stainless steel can be efficiently performed.

[0101] [3. Thin film treatment method for stainless steel]

[0102] The above-mentioned film-forming treatment step is not only useful as a part of the stainless steel manufacturing method, but also as a post-treatment of the stainless steel after manufacturing. The stainless steel film-forming treatment method of the present invention includes the above-mentioned film-forming treatment step. Therefore, in the film-forming treatment used in the film-forming treatment method, the properties and types of the stainless steel, the components of the aqueous composition, the film-forming treatment conditions, etc. are as described above.

[0103] [4. Applications of stainless steel after thin film treatment]

[0104] According to the above-mentioned film-forming treatment step, stainless steel, such as stainless steel foil, whose surface irregularities are suppressed and whose thickness is reduced can be easily manufactured. That is, according to the above-mentioned film-forming treatment step, stainless steel with a thin film without a significant change in surface shape can be obtained by substantially only one-stage treatment, that is, only film-forming treatment in which the aqueous composition of the present invention is brought into contact with the surface of the stainless steel to be treated, or only further appropriate washing (for example, water washing) as needed.

[0105] Furthermore, as described above, the treatment conditions in the thin-film forming treatment are mild and the time required is short, so that the thin-filmed stainless steel can be obtained efficiently.

[0106] Such thin-film stainless steel can be used, for example, for battery collector foils such as solid-state batteries and lithium-ion batteries, solar cell substrates, flexible substrates for electronic devices, substrates for power storage devices, carriers for exhaust gas purification catalysts, etc., electromagnetic wave shielding components and heat dissipation components. The thin-film stainless steel foil obtained by the method for manufacturing stainless steel of the present invention is suitable for use as a battery collector foil, for example.

[0107] Example

[0108] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0109] (Measurement of surface roughness of stainless steel foil)

[0110] The maximum height (Rz) and arithmetic mean roughness (Ra) of the raw material stainless steel foil and the surface treated foils obtained in Examples and Comparative Examples were measured using a laser microscope (Keyence Corporation, product name "VK-X250") in accordance with JIS B0601-2001.

[0111] (thickness)

[0112] The thickness of the surface-treated stainless steel foils in Examples and Comparative Examples and the untreated stainless steel foils in Reference Examples 1 to 4 was measured using a digital micrometer (MDC-25MXT manufactured by Mitutoyo Corporation).

[0113] (density)

[0114] For the surface-treated stainless steel foils in Examples and Comparative Examples and the untreated stainless steel foils in Reference Examples 1 to 4, the density was calculated by the following formula (1) using the weight (D) of the stainless steel foil used, the area (S) of the stainless steel foil used, and the thickness (T) of the stainless steel foil measured as described above.

[0115]

[0116] [Example 1]

[0117] A stainless steel (foil) made of SUS444 having a thickness of 10 μm and a length of 30 mm×30 mm in the longitudinal and lateral directions was prepared (Reference Example 1).

[0118] An aqueous composition was prepared by adding hydrogen peroxide (1.7 g of a 60 wt% aqueous hydrogen peroxide solution) and 72 wt% (143 g) of a 35 wt% aqueous solution of hydrochloric acid to 130 ml of ultrapure water in an amount of 0.5 wt%. The halide ions (Cl2) derived from the hydrochloric acid in the composition - ) is 25% by mass based on the total amount of the aqueous composition.

[0119] The stainless steel foil was immersed in the aqueous composition at a liquid temperature of 30°C for 60 seconds. Then, the immersed stainless steel foil was fully washed with ultrapure water and fully dried to obtain a surface-treated foil. The surface-treated foil obtained was measured according to the above method. The results showed that the thickness was 9 μm, the Ra value of the surface was 0.17 (μm), the Rz value of the surface was 1.53 (μm), and the density was 6.6 g / cm 3 .

[0120] [Examples 2 to 9 / Comparative Examples 1 to 9]

[0121] The stainless steel foil was subjected to the thin-film treatment in the same manner as in Example 1, except that any of the stainless steel to be treated, the properties of the aqueous composition, and the conditions of the thin-film treatment method were changed as shown in Table 1 below, to obtain a surface-treated foil.

[0122] It should be noted that in Comparative Examples 3, 7 and 8, copper ions (Cu 2+ ) were supplied from copper sulfate pentahydrate (CuSO4·5H2O) 3.9 g, 12 g and 12 g respectively, and in Comparative Examples 5 and 6, iron (III) chloride hexahydrate (FeCl3·6H2O) 133 g and 133 g were used respectively.

[0123] The results of the thickness, surface roughness, density and other values ​​of the obtained surface treated foil are shown in Tables 1 to 4. Tables 1 to 4 show the measured values ​​after treatment, calculated based on the values ​​of the reference example before treatment, and the change amounts and change rates thereof.

[0124] [Table 1]

[0125]

[0126] [Table 2]

[0127]

[0128] [Table 3]

[0129]

[0130] [Table 4]

[0131]

[0132] Industrial Applicability

[0133] In the above-mentioned each embodiment of the aqueous composition of specific composition, it is confirmed that stainless steel can be efficiently thinned with less process and short time, and the thickness of stainless steel is reduced before and after treatment. In addition, the increase of significant concavo-convex shape is not confirmed on the surface of the stainless steel after treatment. When the stainless steel, especially the stainless steel foil thinned in a good state of maintaining the appearance is used for battery collector foil, automobile component housing, etc., dielectric substances and organic matter can be effectively attached or maintained. In addition, in the component for heat dissipation, the stainless steel thinned can also be appropriately used.

[0134] Therefore, the present invention can be confirmed to have industrial applicability in the field of processing stainless steel as a material member, for example, a material member used in the above-mentioned products.

Claims

1. An aqueous composition for thinning stainless steel, the aqueous composition comprising 0.01 to 10% by mass of hydrogen peroxide, 12.5 to 40% by mass of halide ions, and 0 to 3.0% by mass of copper ions.

2. The aqueous composition according to claim 1, comprising 0.1 to 5% by mass of hydrogen peroxide, 15 to 30% by mass of halide ions, and 0 to 1.0% by mass of copper ions.

3. A method for producing stainless steel, comprising a thin-film treatment step of thinning the stainless steel using the aqueous composition according to claim 1.

4. The method for producing stainless steel according to claim 3, wherein: The average roughness Ra of the stainless steel surface after the thin-filming treatment is 0.35 μm or less, and the maximum height Rz is 2.5 μm or less.

5. The method for producing stainless steel according to claim 3, wherein: The density of the stainless steel after film treatment is 4.5 g / cm 3 above.

6. The method for producing stainless steel according to claim 3, wherein: The density of the stainless steel after the film treatment is 0.60 times or more of the density of the stainless steel before the film treatment, and the unit of the density of the stainless steel is g / cm 3 .

7. The method for producing stainless steel according to claim 3, wherein: The thickness of the stainless steel after the thin-film treatment is 100 μm or less.

8. The method for producing stainless steel according to claim 3, wherein: The thickness of the stainless steel after the thin-film treatment is 0.95 times or less of the thickness of the stainless steel before the thin-film treatment, and the unit of the thickness of the stainless steel is μm.

9. A method for thin-film treatment of stainless steel, comprising a thin-film treatment step of thin-film treatment of the stainless steel using the aqueous composition according to claim 1.

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