Composition, method for roughening stainless steel surface using the composition, and roughened stainless steel and method for producing the same

Abstract

The present invention provides: a composition with which the surface of a stainless steel is sufficiently roughened in an efficient manner with few steps; a method for roughening a stainless steel; and the like.　The above are achieved by means of a composition for roughening the surface of a stainless steel, said composition containing from 0.1% by mass to 25% by mass of one or more substances that are selected from the group consisting of persulfuric acid and persulfuric acid salts based on the total amount of the composition, and from 1% by mass to 30% by mass of halide ions based on the total amount of the composition.

Description

[Technical field]

[0001] The present invention relates to a composition, in particular to a composition used for surface treatment of stainless steel, a method for roughening the surface of stainless steel, and the like. [Background technology]

[0002] Due to its excellent durability and weather resistance, stainless steel has been considered for use in various fields in recent years. For example, stainless steel is increasingly being used in electronic components, battery current collector foils, and automobile part housings. Specifically, when stainless steel is used for battery current collector foils or automobile part housings, the surface of the stainless steel is roughened in order to allow dielectric substances and organic substances to adhere to it. In addition, when stainless steel is used for heat dissipation purposes, the surface of the stainless steel is roughened in order to promote heat dissipation.

[0003] When stainless steel is used in various products for such purposes, there is a demand for increasing the surface area. To address this, methods are known in which the surface of stainless steel is treated with a treatment solution containing, for example, iron chloride (see, for example, Patent Document 1). However, according to this treatment method, the surface of the stainless steel after treatment still has many flat surfaces, so it cannot be said that the surface is sufficiently roughened for use in the above-mentioned applications.

[0004] In addition, a method for roughening the surface of stainless steel that combines wet peening and a roughening treatment using a chemical solution has been found (for example, Patent Document 2), but these methods require multiple steps, and therefore there is room for improvement in the efficiency of the roughening treatment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-168017 A [Patent Document 2] JP 2015-183239 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, in conventional roughening treatments of stainless steel surfaces, the level of roughening is not always sufficient, and the treatment time and cost are increased due to the need for complicated steps. Therefore, a method that enables a sufficient roughening treatment to be efficiently performed on the surface of stainless steel using simple steps has been desired. [Means for solving the problem]

[0007] As a result of extensive research to achieve the above-mentioned object, the inventors discovered that by using a composition of a specific composition, the surface of stainless steel can be roughened sufficiently and efficiently with fewer steps, and thus completed the present invention.

[0008] That is, the present invention is as follows. [1] A composition for roughening the surface of stainless steel, comprising: The composition contains 0.1 to 25 mass% of one or more selected from the group consisting of persulfuric acid and persulfate salts, based on the total amount of the composition; A composition comprising a halide ion in an amount of 1 to 30 mass % based on the total amount of the composition. [2] The composition according to [1] above, wherein the persulfate comprises an alkali metal salt of persulfate. [3] The composition according to [2] above, wherein the alkali metal salt of persulfuric acid includes at least one of sodium persulfate and potassium persulfate. [4] The composition according to any one of the above [1] to [3], wherein the compound supplying the halide ions comprises one or more selected from the group consisting of hydrochloric acid, sodium chloride, and potassium chloride. [5] The composition according to any one of the above [1] to [4], further comprising water and having a pH value of -1.5 or more and 4.0 or less. [6] The composition according to any one of the above [1] to [5], further comprising copper ions.

[0009] [7] A method for roughening a stainless steel, comprising a roughening step of roughening a stainless steel surface using the composition according to any one of [1] to [6] above. [8] The method for roughening a stainless steel according to the above [7], wherein the roughening treatment is carried out at a temperature of 20 to 60°C. [9] The method for roughening a stainless steel according to the above [7] or [8], wherein the roughening treatment time is 30 seconds to 180 seconds.

[10] The method for roughening a stainless steel according to any one of the above [7] to [9], wherein the maximum height (Rz) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 1.0 μm or more.

[11] The method for roughening a stainless steel according to any one of the above [7] to

[10] , wherein the maximum height (Rz) of the surface of the roughened stainless steel as specified in JIS B 0601-2001 is 5.0 μm or less.

[12] A method for roughening a stainless steel according to any one of [7] to

[11] , wherein the maximum height (Rz) value of the surface of the roughened stainless steel, as specified in JIS B 0601-2001, is 0.5 μm or more greater than the maximum height (Rz) value of the surface of an untreated stainless steel.

[13] The method for roughening a stainless steel according to any one of the above [7] to

[12] , wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 0.1 μm or more.

[14] The method for roughening a stainless steel according to any one of the above [7] to

[13] , wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel as specified in JIS B 0601-2001 is 2.0 μm or less.

[15] A method for roughening a stainless steel according to any one of the above [7] to

[14] , wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel, as defined in JIS B 0601-2001, is at least 0.05 μm greater than the arithmetic mean roughness (Ra) of a flat surface of untreated stainless steel.

[16] The method for roughening a stainless steel according to any one of the above [7] to

[15] , wherein the etching rate of the stainless steel in the roughening treatment is 0.1 μm / min or more.

[0010]

[17] A roughened stainless steel, the surface of which is roughened using the composition according to any one of [1] to [6] above.

[18] The roughened stainless steel according to the above

[17] , wherein the maximum height (Rz) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 1.0 μm or more.

[19] The roughened stainless steel according to

[17] or

[18] above, wherein the maximum height (Rz) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 5.0 μm or less.

[20] The roughened stainless steel according to any one of

[17] to

[19] above, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 0.1 μm or more.

[21] The roughened stainless steel according to any one of

[17] to

[20] above, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 2.0 μm or less.

[22] The stainless steel is defined in the JIS G 4305 standard. Chromium-nickel stainless steels, including SUS304, SUS316, SUS321, SUS347, and SUS329J1; Martensitic stainless steels (chromium stainless steels), including SUS403, SUS410, SUS420J1, SUS420J2, SUS440A, SUS440B, and SUS440C; Ferritic stainless steels (chromium stainless steels), including SUS405, SUS430, SUS434, SUS444, SUS447, and SUSXM27; and Precipitation hardening systems including SUS630, SUS631, and SUH660 (chromium-nickel stainless steels); The roughened stainless steel according to any one of the above

[17] to

[21] , which is one or more types selected from the group consisting of:

[23] The roughened stainless steel according to any one of

[17] to

[22] above, wherein the stainless steel is a stainless steel foil.

[24] A battery current collecting foil, a solar cell substrate, a flexible substrate for an electronic device, a substrate for an electricity storage device, a catalyst carrier, an electromagnetic wave shielding material, or a heat dissipation material, comprising the roughened stainless steel according to any one of

[17] to

[21] above.

[0011]

[25] A method for producing a surface-roughened stainless steel, comprising a roughening step of roughening the stainless steel surface using the composition according to any one of [1] to [6] above.

[26] A method for producing a roughened stainless steel according to the above

[25] , wherein the maximum height (Rz) of the surface of the roughened stainless steel as specified in JIS B 0601-2001 is 1.0 μm or more.

[27] A method for producing a roughened stainless steel according to the above

[25] or

[26] , wherein the maximum height (Rz) of the surface of the roughened stainless steel as specified in JIS B 0601-2001 is 5.0 μm or less.

[28] A method for producing a roughened stainless steel according to any one of

[25] to

[27] above, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel as specified in JIS B 0601-2001 is 0.1 μm or more.

[29] A method for producing a roughened stainless steel according to any one of

[25] to

[28] above, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel as specified in JIS B 0601-2001 is 2.0 μm or less.

[30] A method for producing a roughened stainless steel according to any one of

[25] to

[29] above, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel, as specified in JIS B 0601-2001, is at least 0.05 μm greater than the arithmetic mean roughness (Ra) of a flat surface of untreated stainless steel.

[31] The method for producing a roughened stainless steel according to any one of

[25] to

[30] above, wherein the etching rate of the stainless steel in the roughening treatment is 0.1 μm / min or more.

[32] The stainless steel is defined in the JIS G 4305 standard. Chromium-nickel stainless steels, including SUS304, SUS316, SUS321, SUS347, and SUS329J1; Martensitic stainless steels (chromium stainless steels), including SUS403, SUS410, SUS420J1, SUS420J2, SUS440A, SUS440B, and SUS440C; Ferritic stainless steels (chromium stainless steels), including SUS405, SUS430, SUS434, SUS444, SUS447, and SUSXM27; and Precipitation hardening systems including SUS630, SUS631, and SUH660 (chromium-nickel stainless steels); The method for producing a roughened stainless steel according to any one of the above

[25] to

[31] , wherein the material is one or more selected from the group consisting of:

[33] The method for producing a roughened stainless steel according to any one of

[25] to

[32] above, wherein the stainless steel is a stainless steel foil.

[34] A battery current collecting foil, a solar cell substrate, a flexible substrate for an electronic device, a substrate for an electricity storage device, a catalyst carrier, an electromagnetic wave shielding material, or a heat dissipation material, comprising the roughened stainless steel produced by the manufacturing method according to any one of

[25] to

[33] above. Effect of the Invention

[0012] According to the present invention, the surface of stainless steel can be sufficiently roughened by an efficient method with a small number of steps. [Brief description of the drawings]

[0013] [Figure 1] 1 is a scanning electron microscope (SEM) image showing the surface of stainless steel after roughening treatment in an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will be described in detail below, but the present invention is not limited to the following and various modifications are possible without departing from the gist of the present invention.

[0015] [1. Composition] The composition of the present invention is preferably used for roughening a metal surface, that is, for roughening a metal surface to enlarge the unevenness. Targets for roughening treatment using the composition of the present invention include various metals and alloys, and preferred targets include various stainless steels, the details of which will be described later. The composition of the present invention contains at least one selected from the group consisting of persulfuric acid and persulfate salts in an amount of 0.1 to 25% by mass, based on the total amount of the composition, and 1 to 30% by mass of a halide ion. The composition is preferably water-soluble, and is particularly preferably an aqueous composition containing water, particularly ion-exchanged water or ultrapure water, in addition to the above-mentioned components. Each component of the composition of the present invention (preferably an aqueous composition) will be described below.

[0016] 1-1. Persulfuric acid and persulfate salts The composition of the present invention contains one or more selected from the group consisting of persulfuric acid and persulfate salts. That is, in the composition, either only persulfuric acid or only a persulfate salt may be used, or either only persulfuric acid and a persulfate salt may be used, and further, one type of persulfate may be used alone, or two or more types of persulfate salts may be used in combination. Persulfuric acid (H2SO5) can be produced by a known method, for example, by reacting sulfuric acid or chlorosulfuric acid with a peroxide. The persulfate may be, for example, a salt produced by adding a compound containing a specific counter ion to persulfuric acid.Also, as described in Japanese Patent Publication No. 3778238, the persulfate may be obtained by reacting sodium hydroxide with an electrolyte solution of ammonium sulfate.

[0017] The persulfate is not particularly limited as long as it is a salt of persulfuric acid, and examples thereof include metal salts of persulfuric acid, salts of other inorganic compounds, etc. Among these, metal salts of persulfuric acid are preferred. As the metal salt of persulfate, an alkali metal salt or an alkaline earth metal salt is preferred, and an alkali metal salt is more preferred. More preferred specific examples include sodium persulfate, potassium persulfate, and potassium monohydrogenpersulfate double salt (2KHSO5·KHSO4·K2SO4; oxone). Of these, sodium persulfate and potassium persulfate are particularly preferred, and sodium persulfate is particularly preferred. An example of the salt of an inorganic compound of persulfuric acid is ammonium persulfate. Hereinafter, in this specification, the above-mentioned persulfuric acid and persulfate salts are collectively referred to as a persulfuric acid component.

[0018] The content of the persulfuric acid component in the composition of the present invention (the total content of one or more selected from the group consisting of persulfuric acid and persulfate salts) is 0.1 to 25 mass% based on the total amount of the composition, preferably 1.0 to 25 mass%, more preferably 1.0 to 20 mass% or 2.0 to 22.5 mass%, more preferably 2.0 to 15 mass% or 2.5 to 20 mass%, even more preferably 3.0 to 16 mass%, and particularly preferably 4.0 to 12 mass%. The lower limit of the concentration of the persulfuric acid component contained in the composition may be, for example, 1.0 mass%, 1.5 mass%, 2.0 mass%, 2.5 mass%, 3.0 mass%, 3.5 mass%, 4.0 mass%, 4.5 mass%, 5.0 mass%, etc., and the upper limit of the concentration of the persulfuric acid component contained in the composition may be, for example, 22.5 mass%, 21 mass%, 20 mass%, 19 mass%, 18 mass%, 17 mass%, 16 mass%, 15 mass%, 14 mass%, 13 mass%, 12 mass%, etc. In the composition, when the content (concentration) of the persulfuric acid component, particularly the content (concentration) of sodium persulfate, is within the above-mentioned range, the solubility of the persulfuric acid component is good and the efficiency of the roughening treatment can be improved. The range of the content of the persulfuric acid component may include the above-mentioned upper and lower limits (i.e., a range equal to or less than the upper limit or equal to or more than the lower limit), or may not include the upper and lower limits (i.e., a range less than the upper limit or more than the lower limit), and the same applies to ranges other than the range of the content of the persulfuric acid component.

[0019] As described above, in the composition of the present invention, the use of a persulfuric acid component is preferred, but a peroxide different from the persulfuric acid component (a compound having an -OO- structure in the molecule; here, O represents an oxygen atom) can be used together with or instead of the persulfuric acid component. Specific examples of peroxides different from the persulfuric acid component include peracetic acid, peracetates, percarbonates, percarbonates, perbenzoic acid, perbenzoates, metachloroperbenzoic acid, etc. In addition, even when a peroxide different from the persulfuric acid component is used, the total content of the peroxide in the composition is preferably the same as the content of the persulfuric acid component described above.

[0020] 1-2.Halide ions The type of halide ion contained in the composition of the present invention is not particularly limited, and may be, for example, a fluoride ion (F - ), chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), but chloride ions are preferred from the viewpoints of roughening efficiency, ease of handling, and economy.

[0021] Compounds that supply halide ions are not particularly limited, but include, for example, hydrogen halides, alkali metal halides such as sodium halides and potassium halides, alkaline earth metal halides such as calcium halides, ammonium halides, and copper halides. Among these, from the viewpoint of more effectively and reliably achieving the effects of the present invention, hydrogen halides or alkali metal halides are preferred, and more preferably one or more selected from the group consisting of hydrochloric acid (hydrogen chloride), sodium chloride, and potassium chloride. These may be used alone or in combination of two or more.

[0022] The content of the halide ion in the composition of the present invention is 1 to 30 mass% based on the total amount of the composition, preferably 2.0 to 25 mass%, more preferably 2.0 to 20 mass% or 3.0 to 20 mass%, further preferably 4.0 to 18 mass% or 5.0 to 15 mass%, particularly preferably 5.0 to 17 mass%, 7.0 to 15 mass%, 7.0 to 12 mass%, 8.0 to 15 mass%, or 8.0 to 12 mass%, etc. The range of the content of the halide ion may include the above upper and lower limits (i.e., a range of less than the upper limit or more than the lower limit), or may not include the upper and lower limits (i.e., a range of less than the upper limit or more than the lower limit). The lower limit of the concentration of the halide ions contained in the composition may be, for example, 1.5 mass%, 2.0 mass%, 3.0 mass%, 4.0 mass%, 5.0 mass%, 6.0 mass%, 7.0 mass%, 8.0 mass%, 9.0 mass%, etc., and the upper limit of the concentration of the halide ions contained in the composition may be, for example, 27 mass%, 25 mass%, 22 mass%, 20 mass%, 19 mass%, 18 mass%, 17 mass%, 16 mass%, 15 mass%, 14 mass%, 13 mass%, 12 mass%, etc. In the composition, if the content (concentration) of the halide ions is within the above-mentioned range, the efficiency of the roughening treatment can be improved.

[0023] 1-3.Water The composition of the present invention may contain water, and preferably contains water. The water is not particularly limited, but is preferably water from which metal ions, organic impurities, particles, etc. have been removed by distillation, ion exchange treatment, filtration treatment, various adsorption treatments, etc., more preferably pure water, and particularly preferably ultrapure water.

[0024] The water content in the composition of the present invention is not particularly limited, but is preferably 45 to 98.9 mass%, more preferably 55 to 97 mass%, even more preferably 65 to 95 mass%, and particularly preferably 75 to 90 mass%, based on the total amount of the composition. The composition of the present invention is preferably a solution, and preferably does not contain any components that are insoluble in the solution, such as solid particles such as abrasive particles.

[0025] 1-4. Other active ingredients in the composition The composition of the present invention may contain active components other than the above-mentioned persulfuric acid component, peroxide, and halide ions. For example, copper ions may be added to the composition as a component capable of causing a substitution reaction with nickel and chromium, which are components of stainless steel. The type of copper ion source is not particularly limited as long as it is a copper compound capable of supplying copper ions in the composition. For example, copper compounds capable of supplying copper ions include copper sulfates such as copper (II) sulfate, copper chlorides such as copper (II) chloride, copper tetrafluoroborate, copper (II) bromide, copper (II) oxide, copper phosphate, copper acetate, copper formate, copper nitrate, etc., which may be anhydrous or hydrated (e.g., pentahydrate). Among these, copper sulfate or copper chloride is preferred, copper (II) sulfate or copper chloride is more preferred, and copper (II) sulfate is even more preferred. These may be used alone or in combination of two or more.

[0026] The content of copper ions that may be contained in the composition of the present invention is preferably 0.25 to 40 mass%, more preferably 1.0 to 30 mass%, even more preferably 3.0 to 25 mass%, and particularly preferably 5.0 to 20 mass%, based on the total amount of the composition.

[0027] The copper compound and the compound that supplies the above-mentioned halide ions may overlap. For example, when a copper halide is used as a source of copper ions, the copper halide also corresponds to the above-mentioned halide ion source. The copper halide is preferably copper chloride.

[0028] 1-5. Additives contained in the composition The composition of the present invention may contain additives in addition to the active components such as the persulfuric acid component and halide ions described above, as long as the effects of the present invention are exhibited. Examples of additives include heterocyclic nitrogen compounds (azole compounds) and organic solvents. These may be used alone or in combination of two or more. Further, additives include surfactants, pH adjusters, etc., but it is preferable that these are not included in the composition of the present invention. The content of additives that may be contained in the composition of the present invention is preferably 10 mass % or less, more preferably 5.0 mass % or less, even more preferably 2.0 mass % or less, and particularly preferably 1.0 mass % or less, based on the total amount of the composition.

[0029] 1-6. Functions and properties of the composition It is believed that the composition containing the above-mentioned components functions in the roughening treatment of stainless steel surfaces as follows. The halide ions are responsible for pitting the oxide film that normally forms on the surface of stainless steel. The persulfuric acid component oxidizes and ionizes the metal components of stainless steel in an acidic aqueous solution, causing a corrosion reaction. The corrosion reaction occurs irregularly on the stainless steel, resulting in a roughened surface. It is also believed that peroxides other than the persulfuric acid component, such as peracetic acid, can play a similar role to the persulfuric acid component.

[0030] The composition of the present invention is prepared by adding the above-mentioned persulfuric acid component, halide ion supplying component, water, and other components as required, and stirring until homogeneous. The properties of the composition are not particularly limited, but the pH value is preferably -1.5 to 4.0, more preferably -1.0 to 3.0, even more preferably -0.75 to 2.5, and particularly preferably -0.5 to 2.0. The pH value of the composition is, for example, less than 1.0. The pH value can be measured by the method described in the Examples.

[0031] [2. Roughening method for stainless steel] In the method for roughening a stainless steel according to the present invention, a roughening step is carried out in which the stainless steel surface is roughened using the above-mentioned composition. Specifically, the roughening step performed in the present invention includes contacting the above-mentioned composition with stainless steel. The method of contacting the composition with the stainless steel is not particularly limited, but includes, for example, a method of immersing the stainless steel to be treated in the composition of the present invention, a method of dropping the composition of the present invention onto the stainless steel to be treated (sheet-feed spin treatment), a method of spraying the composition of the present invention onto the stainless steel to be treated (spray treatment), and the like, and any method may be adopted. For example, a method of spraying the composition of the present invention onto a stainless steel processed into a specific shape to obtain a roughened stainless steel, a method of installing a dropping device, spraying device, or immersion device for the composition of the present invention between stainless steel foil rolls, and a method of passing the composition by the vicinity of the above device while the stainless steel foil is unrolled and moved from the roll on which the untreated stainless steel foil was wound by a roll-to-roll method, and the like can be mentioned.

[0032] In the roughening step, the temperature of the roughening treatment is preferably 20 to 60° C., more preferably 25 to 55° C., and particularly preferably 30 to 50° C. Thus, the method of roughening treatment of stainless steel of the present invention is excellent in that roughening of the stainless steel surface proceeds even at temperatures that are not so high, for example, at temperatures of 20 to 30° C. Here, the temperature of the roughening treatment refers to the temperature when the composition is brought into contact with the stainless steel surface, particularly the liquid temperature of the composition brought into contact with the stainless steel surface. In the roughening step, the roughening treatment time is preferably 30 to 180 seconds, more preferably 30 to 120 seconds, even more preferably 40 to 100 seconds, and particularly preferably 50 to 90 seconds. Thus, the method for roughening stainless steel of the present invention is excellent in that the roughening of stainless steel progresses without a long time. Here, the roughening treatment time refers to the time during which the composition is brought into contact with the stainless steel surface. For example, it is the time during which the stainless steel is immersed in the composition, or the time from when the composition is sprayed on the surface of the stainless steel to when the aqueous composition is removed by water or the like.

[0033] According to the method for roughening stainless steel of the present invention, it is possible to make the maximum height (Rz) of the surface of the roughened stainless steel (herein also referred to as roughened stainless steel, and stainless steel includes roughened stainless steel foil (film or sheet)) 1.0 μm or more, for example, 1.5 μm or more, or 2.0 μm or more. According to the method for roughening stainless steel of the present invention, it is preferable that the maximum height (Rz) of the stainless steel surface can be made 3.0 μm or more, or 4.0 μm or more, more preferably 4.5 μm or more, even more preferably 5.0 μm or more, and particularly preferably 5.5 μm or more. Furthermore, the upper limit of the maximum height (Rz) of the roughened stainless steel surface is not particularly limited, but the Rz value may be, for example, 10.0 μm or less, 7.0 μm or less, or 5.0 μm or less. The maximum height (Rz) of the surface of stainless steel before it is subjected to a roughening treatment (untreated stainless steel) is not particularly limited, but is, for example, about 0.1 to 2.0 μm, 0.2 to 2.0 μm, 0.4 to 2.0 μm, or 1.0 to 1.5 μm.

[0034] According to the method for roughening stainless steel of the present invention, it is possible to make the maximum height (Rz) of the roughened stainless steel surface at least 1.0 μm greater than the maximum height (Rz) of the untreated stainless steel surface, preferably at least 1.5 μm or at least 2.0 μm greater, and more preferably at least 3.0 μm greater.

[0035] According to the method for roughening stainless steel of the present invention, it is possible to make the arithmetic mean roughness (Ra) of the roughened stainless steel surface 0.1 μm or more, for example, 0.2 μm or more. According to the method for roughening stainless steel of the present invention, it is preferable that the arithmetic mean roughness (Ra) of the roughened stainless steel surface be 0.3 μm or more, more preferably 0.4 μm or more, even more preferably 0.6 μm or more, and especially preferably 0.8 μm or more. Furthermore, the upper limit of the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel is not particularly limited, but may be, for example, 2.0 μm or less, 1.5 μm or less, or 1.0 μm or less. The arithmetic mean roughness (Ra) of untreated stainless steel is not particularly limited, but is, for example, 0.01 to 0.3 μm, or 0.05 to 0.3 μm.

[0036] According to the stainless steel roughening treatment method of the present invention, it is possible to make the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel at least 0.05 μm greater than the arithmetic mean roughness (Ra) of the flat surface of untreated stainless steel, preferably at least 0.1 μm or at least 0.2 μm greater, and more preferably at least 0.3 μm greater.

[0037] The above-mentioned maximum height (Rz) and arithmetic mean roughness (Ra) are calculated in accordance with JIS B 0601-2001. The device used for the measurement is not particularly limited, but for example, a laser microscope can be used.

[0038] The etching rate of the stainless steel in the roughening treatment is not particularly limited, but is, for example, 0.1 μm / min or more, preferably 0.5 μm / min or more, more preferably 0.7 μm / min or more, even more preferably 1.0 μm / min or more, particularly preferably 1.2 μm / min or more, and particularly preferably 1.4 μm / min or more.

[0039] According to the above-mentioned method for roughening stainless steel, a stainless steel having an enlarged surface unevenness can be obtained by substantially one-step treatment, i.e., only the roughening step of contacting the composition of the present invention with the surface of the stainless steel to be treated, or by further performing appropriate washing (e.g., washing with water) as necessary. Furthermore, as described above, the treatment conditions in the roughening treatment are mild and the time required is short, so that according to the present invention, the roughening treatment of stainless steel can be efficiently performed. For example, according to the present invention, which does not require treatment such as wet peening for refining the crystals that form the surface of stainless steel, the surface of stainless steel can be roughened quickly by a simpler method.

[0040] [3. Stainless Steel] The type of stainless steel to be roughened with the composition of the present invention is not particularly limited, but examples thereof include the following: In other words, as stipulated in the JIS G4305 standard, Chromium-nickel stainless steels, including SUS304, SUS316, SUS321, SUS347, and SUS329J1; Martensitic stainless steels (chromium stainless steels), including SUS403, SUS410, SUS420J1, SUS420J2, SUS440A, SUS440B, and SUS440C; Ferritic stainless steels (chromium stainless steels) including SUS405, SUS430, SUS434, SUS444, SUS447, and SUSXM27; These include precipitation hardening systems (chromium-nickel stainless steels) including SUS630, SUS631, and SUH660. The size, thickness, and shape of the stainless steel to be roughened are not particularly limited, and the roughening treatment can be performed on, for example, stainless steel foil. The thickness of the stainless steel foil to be roughened is not particularly limited, but is, for example, 1 μm to 500 μm, and preferably 10 μm to 100 μm.

[0041] As described above, the composition of the present invention can roughen the surface of a wide variety of stainless steels. In addition, the composition of the present invention has the characteristic that it can roughen the surface of robust stainless steels such as SUS444, which cannot be roughened by an aqueous composition containing hydrogen peroxide, hydrochloric acid, or the like as active ingredients.

[0042] As described above, the maximum height (Rz) of the roughened stainless steel surface is, for example, 0.5 μm or more, preferably 1.0 μm or more, more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and particularly preferably 2.4 μm or more. Furthermore, the upper limit of the maximum height (Rz) of the roughened stainless steel surface is not particularly limited, but may be, for example, 10.0 μm or less, 7.0 μm or less, 5.0 μm or less, or 4.0 μm or less. The arithmetic mean roughness (Ra) of the surface of the roughened stainless steel is, for example, 0.1 μm or more, preferably 0.15 μm or more, more preferably 0.2 μm or more, even more preferably 0.3 μm or more, and especially preferably 0.4 μm or more. Furthermore, the upper limit of the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel is not particularly limited, but is, for example, 0.70 μm or less, and preferably 0.50 μm or less.

[0043] [4. Stainless steel manufacturing method] The method for producing stainless steel of the present invention includes at least the roughening step described above. According to the method for producing stainless steel of the present invention, it is possible to produce stainless steel having a surface that is rougher than before the roughening treatment, i.e., a surface with more projections and recesses than before the treatment. The stainless steels that can be used in the method for producing stainless steel of the present invention are as described above in the section [3. Stainless steel]. The maximum height (Rz) and arithmetic mean roughness (Ra) of the roughened stainless steel surface obtained by the stainless steel manufacturing method of the present invention are as described above in the sections [2. Roughening method for stainless steel] or [3. Stainless steel]. The roughened stainless steel obtained by the stainless steel manufacturing method of the present invention can be used for applications such as current collector foils for batteries 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 and the like, electromagnetic wave shielding materials, and heat dissipation materials. The roughened stainless steel foil obtained by the stainless steel manufacturing method of the present invention can be suitably used, for example, as current collector foils for batteries. EXAMPLES

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0045] (Measurement of surface roughness of stainless steel foil) The maximum height (Rz) and arithmetic mean roughness (Ra) of the raw stainless steel foil and the surface-treated foils obtained in the examples and comparative examples were measured using a laser microscope (manufactured by Keyence Corporation, product name "VK-X250") in accordance with JIS B 0601-2001.

[0046] (Surface observation of stainless steel foil) The surface shapes of the surface-treated foils obtained in the examples and comparative examples were observed using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, product name "S-3400N").

[0047] (pH value measurement) The pH value of the compositions in the examples and comparative examples was measured at 25° C. using a pH meter (pH meter F-52, manufactured by Horiba, Ltd.).

[0048] (Etching rate (ER) measurement) For the surface-treated foils obtained in the examples and comparative examples, the ER value (μm / min) was calculated by dividing the mass difference (D) of the stainless steel foil before and after treatment with the composition by the area S of the stainless steel foil used (area treated with the composition), the density (ρ) of the stainless steel foil, and the treatment time (T). That is, the ER value is calculated according to the following formula (1). The unit of the ER value calculated directly by formula (1) is (cm / min), but the value converted into the unit of (μm / min) is shown in Table 1 below.

number

[0049] [Example 1] A stainless steel foil having a thickness of 20 μm, a length and width of 30 mm×30 mm, and made of SUS 444 was prepared. The Rz of the stainless steel foil measured according to the above-mentioned "Measurement of surface roughness of stainless steel foil" was 0.48 μm, and the Ra was 0.07 μm. A composition was prepared by adding 7% by mass (14 g) of sodium persulfate and 28% by mass (57 g) of a 35 wt % aqueous solution of hydrochloric acid to 129 ml of ultrapure water. - The concentration of was 10% by mass based on the total amount of the composition.

[0050] The above stainless steel foil was first immersed in the above composition at a liquid temperature of 45°C for 60 seconds. Next, the immersed stainless steel foil was thoroughly washed with ultrapure water and then thoroughly dried to obtain a surface-treated foil. The obtained surface-treated foil was observed according to the above "Surface Observation of Stainless Steel Foil". The microscope image is shown in Figure 1. In addition, the maximum height of the surface of the obtained surface-treated foil was measured according to the above "Measurement of Surface Roughness of Stainless Steel Foil", and the Rz value was 2.41 μm and the Ra value was 0.46 μm. In addition, the etching rate was 1.05 μm / min.

[0051] [Examples 2 to 5] As shown in Table 1 below, the sodium persulfate and chloride ions (Cl - The surface of the stainless steel foil was treated in the same manner as in Example 1, except that the concentration of ) was changed, and the surface roughness and etching rate were measured. The values ​​of Rz, Ra, and etching rate are as shown in Table 1.

[0052] [Example 6] As shown in Table 1 below, the stainless steel foil to be roughened was changed, and the surface of the stainless steel foil was treated in the same manner as in Example 1, and the surface roughness and etching rate were measured. The values ​​of Rz, Ra, and etching rate are as shown in Table 1.

[0053] [Comparative Example 1] A stainless steel foil made of SUS444 and having a thickness of 20 μm and dimensions of 30 mm×30 mm was prepared. A composition was prepared by adding 28 mass % (57 g) of a 35 wt % aqueous solution of hydrochloric acid to 143 ml of ultrapure water.

[0054] The above stainless steel foil was first immersed in the above composition at a liquid temperature of 45° C. for 60 seconds. The immersed stainless steel foil was then thoroughly washed with ultrapure water and thoroughly dried to obtain a surface-treated foil. The maximum height of the surface of the obtained surface-treated foil was measured according to the above "Measurement of surface roughness of stainless steel foil". No roughening of the surface was observed, and the values ​​of Ra and Rz were unchanged from before the treatment.

[0055] [Comparative Example 2] A stainless steel foil made of SUS444 and having a thickness of 20 μm and dimensions of 30 mm×30 mm was prepared. A composition was prepared by adding 7 mass % (14 g) of sodium persulfate to 186 ml of ultrapure water.

[0056] The above stainless steel foil was first immersed in the above composition at a liquid temperature of 45° C. for 60 seconds. The immersed stainless steel foil was then thoroughly washed with ultrapure water and thoroughly dried to obtain a surface-treated foil. The maximum height of the surface of the obtained surface-treated foil was measured according to the above "Measurement of the surface roughness of stainless steel foil". No sign of roughening of the surface was observed, and the values ​​of Ra and Rz were unchanged from before the treatment.

[0057] [Comparative Example 3] As shown in Table 1 below, the sodium persulfate and chloride ions (Cl - The surface of the stainless steel foil was treated in the same manner as in the above-mentioned Comparative Example, except that the concentration of As a result, no roughening of the surface was observed, and the Ra and Rz values ​​were unchanged from before the treatment.

[0058] [Table 1]

[0059] As is clear from Table 1, an aqueous composition containing a persulfuric acid component and a halide ion in combination at contents within a specified range enabled efficient roughening treatment of stainless steel.

[0060] Industrial Applicability According to the present invention, by using a composition having a specific composition, the surface of stainless steel can be sufficiently and efficiently roughened with fewer steps and in a short time. If the stainless steel having such a roughened surface is used for battery current collector foils, automobile part housings, etc., dielectric substances and organic substances can be effectively attached and held. Furthermore, the stainless steel having a roughened surface can be suitably used for members for dissipating heat. Furthermore, since efficient roughening can be achieved with a composition containing a relatively small number of active ingredients, the present invention also makes it possible to reduce the cost of stainless steel treatment. Therefore, the present invention has industrial applicability in the field of surface roughening treatment of material members, such as stainless steel used in the above-mentioned products.

Claims

1. A composition for roughening a stainless steel surface, comprising: The composition contains 2.0 to 25% by mass of one or more selected from the group consisting of persulfuric acid and persulfate salts, based on the total amount of the composition; The composition contains 1 to 30 mass% of chloride ions based on the total amount of the composition, Contains water or contains water and copper ions, A composition, wherein the content of additives (excluding the component or a compound that provides the component) is 10 mass % or less based on the total amount of the composition.

2. The composition of claim 1 , wherein the persulfate comprises an alkali metal salt of persulfate.

3. 3. The composition of claim 2, wherein the alkali metal salt of persulfate comprises one or more of sodium persulfate or potassium persulfate.

4. The composition according to any one of claims 1 to 3, comprising at least one compound selected from the group consisting of hydrochloric acid, sodium chloride, and potassium chloride as the compound that supplies chloride ions.

5. A composition described in any one of claims 1 to 4, having a pH value of -1.5 or more and 4.0 or less.

6. The composition according to any one of claims 1 to 5, comprising copper ions.

7. A method for roughening a stainless steel surface, comprising a roughening step of roughening a stainless steel surface using the composition according to any one of claims 1 to 6.

8. The method for roughening a stainless steel according to claim 7, wherein the temperature of the roughening treatment is 20 to 60°C.

9. The method for roughening a stainless steel according to claim 7 or 8, wherein the roughening treatment time is from 30 seconds to 180 seconds.

10. The method for roughening a stainless steel according to any one of claims 7 to 9, wherein the maximum height (Rz) of the surface of the roughened stainless steel, as defined by JIS B 0601-2001, is 1.0 µm or more.

11. The method for roughening a stainless steel according to any one of claims 7 to 10, wherein the maximum height (Rz) of the surface of the roughened stainless steel, as defined in JIS B 0601-2001, is 5.0 μm or less.

12. The method for roughening a stainless steel according to any one of claims 7 to 11, wherein the maximum height (Rz) of the surface of the roughened stainless steel, as defined in JIS B 0601-2001, is at least 0.5 μm greater than the maximum height (Rz) of the surface of an untreated stainless steel.

13. The method for roughening a stainless steel according to any one of claims 7 to 12, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel is 0.1 µm or more as defined in JIS B 0601-2001.

14. The method for roughening a stainless steel according to any one of claims 7 to 13, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel, as defined in JIS B 0601-2001, is 2.0 μm or less.

15. The method for roughening a stainless steel according to any one of claims 7 to 14, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel, as defined in JIS B 0601-2001, is at least 0.05 μm greater than the arithmetic mean roughness (Ra) of the surface of an untreated stainless steel.

16. The method for roughening a stainless steel according to any one of claims 7 to 15, wherein the etching rate of the stainless steel in the roughening treatment is 0.1 µm / min or more.

17. A method for producing a surface-roughened stainless steel, comprising a roughening step of roughening a stainless steel surface with the composition according to any one of claims 1 to 6.

18. The method for producing a roughened stainless steel according to claim 17, wherein the maximum height (Rz) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 1.0 μm or more.

19. The method for producing a roughened stainless steel according to claim 17 or 18, wherein the maximum height (Rz) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 5.0 μm or less.

20. The method for producing a roughened stainless steel according to any one of claims 17 to 19, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 0.1 μm or more.

21. The method for producing a roughened stainless steel according to any one of claims 17 to 20, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel as defined in JIS B 0601-2001 is 2.0 μm or less.

22. The method for producing a roughened stainless steel according to any one of claims 17 to 21, wherein the arithmetic mean roughness (Ra) of the surface of the roughened stainless steel, as defined in JIS B 0601-2001, is at least 0.05 μm greater than the arithmetic mean roughness (Ra) of the surface of an untreated stainless steel.

23. The method for producing a roughened stainless steel according to any one of claims 17 to 22, wherein the etching rate of the stainless steel in the roughening treatment is 0.1 μm / min or more.

24. The stainless steel is defined by the JIS G 4305 standard. Chromium-nickel stainless steels, including SUS304, SUS316, SUS321, SUS347, and SUS329J1; Martensitic stainless steels (chromium stainless steels) including SUS403, SUS410, SUS420J1, SUS420J2, SUS440A, SUS440B, and SUS440C; 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; The method for producing roughened stainless steel according to any one of claims 17 to 23, wherein the surface roughening step is performed using one or more types of material selected from the group consisting of:

25. The method for producing a roughened stainless steel according to any one of claims 17 to 24, wherein the stainless steel is a stainless steel foil.

26. A manufacturing method described in any of claims 17 to 25, wherein the stainless steel is a roughened stainless steel used for a battery current collecting foil, a solar cell substrate, a flexible substrate for an electronic device, a substrate for an electricity storage device, a catalyst carrier, an electromagnetic wave shielding material, or a heat dissipation material.

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