Method for producing aluminum having surface-treated film, aluminum having surface-treated film, and container partially composed of aluminum having surface-treated film

Abstract

To prevent an object from being contaminated with iodine-specific color or odor even when the object is brought into contact with aluminum which has an oxide film formed on its surface, with fine pores or fine irregularities of the oxide film being impregnated with iodine or an iodine compound.SOLUTION: A method for producing aluminum having a surface-treated film comprises: an anodizing process for forming an oxide film having fine pores on the surface of aluminum; an iodine impregnation process for impregnating the fine pores with iodine by electrophoretic deposition of iodine; and a pore-sealing process of the oxide film. In the anodizing process, an oxide film having a thickness of 10 to 50 μm is formed in a sulfuric acid electrolyte having a temperature of 5 to 15°C and a sulfuric acid concentration of 15 to 25 wt.%. In the iodine impregnation process, an electrolytic voltage of 30 to 110 V is applied for 1 to 5 minutes to a solution of iodine or an iodine compound adjusted such that the iodine content is 1.0 to 5.0 wt.%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a method for producing aluminum having a surface treatment film, aluminum having a surface treatment film, and a container at least partly made of aluminum having a surface treatment film. [Background technology]

[0002] The process of forming an oxide film on the surface of aluminum using an electrolyte such as sulfuric acid electrolyte or oxalic acid electrolyte is known as anodizing. The aluminum oxide (Al2O3) itself formed on the surface of aluminum as an oxide film is also often called anodizing. The main purposes of anodizing include improving corrosion resistance, coloring, providing lubricity and wear resistance, and electrical insulation.

[0003] When aluminum is anodized, fine pores or irregularities are generated on the surface. Therefore, a sealing treatment is usually performed after the anodizing treatment to close the fine pores or irregularities. Typical sealing treatments include pressurized steam sealing, which uses pressurized steam in a high-pressure vessel, boiling water sealing, which seals in boiling water, and nickel acetate sealing, which seals in an aqueous solution of nickel acetate.

[0004] Furthermore, a technique for imparting bactericidal and antibacterial properties to metal oxide films, including aluminum, by impregnating the micropores or irregularities formed in the oxide film with iodine or an iodine compound is known (see, for example, Patent Document 1). As a practical example, after anodizing aluminum, a material with bactericidal and antibacterial properties can be produced by impregnating the micropores in the oxide film with polyvinylpyrrolidone iodide (PVPI), a readily available iodine compound, by electrophoretic deposition. PVPI is also known as povidone iodine.

[0005] The technique described in Patent Document 1 does not involve a sealing treatment after PVPI impregnation, i.e., it forms a coating structure in which PVPI is exposed to the outside. This is because if a sealing treatment is performed after PVPI impregnation, the PVPI, which exhibits bactericidal and antibacterial properties immediately after the sealing treatment, will be trapped in the micropores or microscopic irregularities of the oxide coating, whereas if a sealing treatment is performed using a conventional sealing agent, iodine will dissolve into the sealing agent, causing discoloration.

[0006] Therefore, a technique has been proposed in which a sealing treatment is performed after impregnation with PVPI so that the PVPI is partially exposed (see, for example, Patent Document 2). The method described in Patent Document 2 involves immersion dyeing with PVPI mixed with a dye into the micropores or microscopic irregularities of the oxide film, or impregnation with PVPI by electrophoretic deposition, followed by at least a low-temperature sealing treatment and, if necessary, a high-temperature sealing treatment.

[0007] Low-temperature sealing is a process in which a substrate with an oxide film formed thereon is immersed in a low-temperature sealing solution primarily composed of nickel fluoride or nickel acetate to partially close the micropores or microscopic irregularities to the extent that PVPI can at least vaporize and diffuse, while high-temperature sealing is a process in which the micropores or microscopic irregularities are completely closed to the extent that PVPI no longer vaporizes or diffuses. Furthermore, sealing processes that include at least the low-temperature sealing process are believed to suppress the vaporization of PVPI and thereby exhibit weather resistance.

[0008] In addition, Patent Document 2 describes that mixing PVPI into a sealing agent causes PVPI to diffuse not only into the micropores or microscopic irregularities but also from the film-like sealing portion. Therefore, even when a high-temperature sealing treatment is performed, PVPI diffuses from the film-like sealing portion, and even after the film-like sealing portion wears away, the PVPI diffuses from within the micropores or microscopic irregularities, thereby continuing to exhibit bactericidal and antibacterial properties.

[0009] Other known methods include coloring with an organic dye or electrolytic coloring prior to impregnation of the micropores or microscopic irregularities of an oxide film with an iodine compound by electrophoretic deposition (see, for example, Patent Document 3), and using trimethylsulfoxonium iodide (TMSOI) or trimethylsulfonium iodide (TMSI) as the iodine compound (see, for example, Patent Documents 4 to 6).

[0010] It is understood that the method described in Patent Document 3 does not involve a sealing treatment after impregnation with an iodine compound, whereas the methods described in Patent Documents 4 to 6 are capable of a sealing treatment using a sealing agent, a sealing treatment using hot water at 80°C or higher without using a sealing agent, and a treatment in which the oxide film is immersed in an aqueous iodine compound solution at 85°C or higher to perform both the impregnation with the iodine compound and the sealing treatment. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-054194 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-350741 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-169996 [Patent Document 4] Japanese Patent Application Laid-Open No. 2012-197481 [Patent Document 5] Japanese Patent Application Laid-Open No. 2012-197482 [Patent Document 6] Japanese Patent Application Laid-Open No. 2014-047380 Summary of the Invention [Problem to be solved by the invention]

[0012] As described above, when aluminum having an oxide film formed on its surface and having iodine or an iodine compound impregnated into the micropores or microscopic irregularities of the oxide film is brought into contact with an object, the reddish-brown color of iodine may adhere to the object. That is, the reddish-brown color characteristic of iodine may fade. In addition, not only may the odor of iodine be generated, but the odor of iodine may also be transferred to the object. As a result, there is a problem in that it is difficult to construct a container, vessel, or the like using aluminum having an oxide film formed on its surface and having iodine or an iodine compound impregnated into the micropores or microscopic irregularities of the oxide film.

[0013] In response to this, it has been proposed that sealing with a low-temperature sealing solution containing nickel fluoride or nickel acetate as the main component can reduce the adhesion of the iodine color to the object and the transfer of the iodine smell to the object, but there is a problem in that nickel and nickel oxide have been reported to be harmful to the human body, or at least are suspected to be harmful to the human body.For this reason, in cases where there is a need to avoid using nickel, such as in medical devices, sealing with a sealing solution cannot be performed.

[0014] On the other hand, the iodine compounds TMSOI and TMSI are much more expensive than PVPI, so it is desirable to use PVPI, which is more readily available, as the iodine compound.

[0015] Therefore, an object of the present invention is to make it difficult for the color and odor characteristic of iodine or iodine compounds to adhere to an object even when the object is brought into contact with aluminum having an oxide film formed on the surface and having iodine or an iodine compound impregnated into the micropores or microscopic irregularities of the oxide film, regardless of the type of iodine compound.

[0016] Another object of the present invention is to realize, without using nickel, an object that is less likely to acquire the color or odor characteristic of iodine or iodine compounds even when the object is brought into contact with aluminum that has an oxide film formed on its surface and that has iodine or iodine compounds impregnated into the micropores or microscopic irregularities of the oxide film, regardless of the type of iodine compound. [Means for solving the problem]

[0017] A method for producing aluminum having a surface treatment film according to an embodiment of the present invention includes anodizing treatment to form an oxide film having fine pores or recesses on the surface of aluminum, an iodine impregnation treatment to impregnate the fine pores or recesses of the oxide film with iodine or an iodine compound by electrophoretic deposition of iodine or an iodine compound, and a pore-sealing treatment of the oxide film after the iodine impregnation treatment. The anodizing treatment forms an oxide film having a thickness of 10 μm to 50 μm in an electrolytic solution containing iodine or an iodine compound at a temperature of 5°C to 15°C and a sulfuric acid concentration of 15 wt% to 25 wt%. The iodine impregnation treatment involves applying an electrolytic voltage of 30 V to 110 V for 1 minute to 5 minutes to the iodine or iodine compound solution containing iodine at a concentration of 1.0 wt% to 5.0 wt%.

[0018] Furthermore, a method for producing aluminum having a surface treatment film according to an embodiment of the present invention includes an anodizing treatment for forming an oxide film having fine pores or recesses on the surface of the aluminum, an iodine impregnation treatment for impregnating the fine pores or recesses of the oxide film with iodine or an iodine compound, and a pore sealing treatment for the oxide film after the iodine impregnation treatment, in which hot water sealing is performed using hot water at a temperature of 60°C or higher but lower than 80°C.

[0019] Furthermore, a method for producing aluminum having a surface treatment film according to an embodiment of the present invention includes an anodizing treatment for forming an oxide film having fine pores or recesses on the surface of the aluminum, an iodine impregnation treatment for impregnating the fine pores or recesses of the oxide film with iodine or an iodine compound, and a decolorizing and deodorizing treatment for reducing the diffusion of the color and odor of the iodine or iodine compound after the iodine impregnation treatment.

[0020] Furthermore, the aluminum having a surface treatment film according to an embodiment of the present invention has, as the surface treatment film, an oxide film having fine pores or recesses, and iodine or an iodine compound impregnated in the fine pores or recesses, and the oxide film has a sealing degree of 40 μS or more and 60 μS or less as determined by an admittance measurement test.

[0021] Furthermore, the aluminum having a surface treatment film according to an embodiment of the present invention has, as the surface treatment film, an oxide film having fine pores or recesses, iodine or an iodine compound impregnated in the fine pores or recesses, and bayerite precipitated in the fine pores or recesses.

[0022] Furthermore, the container according to the embodiment of the present invention is at least partially made of aluminum having the above-described surface treatment film. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a flowchart showing the steps of a method for producing aluminum having a surface treatment film according to a first embodiment of the present invention. [Figure 2] 2 is a schematic diagram showing the detailed structure of aluminum having a surface treatment film produced by the production method shown in FIG. 1. [Figure 3] 2 is a table showing the relationship between the temperature of the electrolyte in the anodizing treatment shown in FIG. 1 and the state of the surface treatment film. [Figure 4] 2 is a table showing the relationship between the current application time, sealing method, and state of the surface treatment film in the iodine impregnation treatment shown in FIG. 1. [Figure 5] 5 is a flowchart showing the steps of a method for producing aluminum having a surface treatment film according to a second embodiment of the present invention. [Figure 6] 6 is a table comparing the state of the surface treatment film after hot water sealing shown in FIG. 5 with the state of the surface treatment film after other sealing treatments. [Figure 7] 6 is a table showing the relationship between the hot water sealing treatment time shown in FIG. 5 and the state of the surface treatment film. [Figure 8]6 is a flowchart showing the steps of a method for producing aluminum having a surface treatment film according to a third embodiment of the present invention. [Figure 9] 10 is a flowchart showing the steps of a method for producing aluminum having a surface treatment film according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] A method for producing aluminum having a surface treatment film, aluminum having a surface treatment film, and a container at least partly made of aluminum having a surface treatment film according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0025] (First embodiment) FIG. 1 is a flowchart showing the steps of a method for producing aluminum having a surface treatment film according to a first embodiment of the present invention.

[0026] As shown in FIG. 1, the method for producing aluminum having a surface treatment film includes step P1, which performs pretreatment, step P2, which performs anodizing (anodizing) treatment, step P3, which performs iodine impregnation treatment by electrophoretic deposition, step P4, which performs sealing treatment, and step P5, which performs drying.

[0027] The pretreatment in step P1 involves known processes such as degreasing, etching, and desmutting. Degreasing is a process in which oil is removed by cleaning the aluminum surface with a solvent, alkali, acid, or the like. Etching is a process in which scratches are removed and oil remaining after degreasing is removed by dissolving the aluminum surface with an alkaline solution such as sodium hydroxide solution. Desmutting is a process in which residue remaining on the aluminum surface during etching is removed with a nitric acid solution, or the like. Other pretreatment processes that may be used include chemical polishing and chemical matte finishing.

[0028] The anodizing treatment in step P2 is a treatment to form an oxide film having fine pores or recesses on the surface of aluminum by electrolysis. Specifically, the aluminum is immersed in an acidic aqueous solution to serve as an anode, and an electric current is passed through to form an oxide film on the surface of the aluminum.

[0029] The anodizing treatment in step P2 is carried out in a sulfuric acid solution at a temperature of 5°C to 15°C and a sulfuric acid concentration of 15 wt% to 25 wt%, so as to form an oxide film having a thickness of 10 μm to 50 μm.

[0030] The iodine impregnation treatment in step P3 is a treatment in which iodine or an iodine compound is impregnated into the fine pores or recesses of the oxide film by electrophoretic deposition of iodine or an iodine compound. Therefore, the anodizing treatment in step P2 corresponds to the primary electrolytic treatment, and the iodine impregnation treatment in step P3 corresponds to the secondary electrolytic treatment.

[0031] PVPI is a typical example of an easily available iodine compound, but electrophoresis can also be performed using TMSOI, TMSI, other iodine compounds, or iodine alone. Depending on the type of iodine compound, only iodine may be electrodeposited into the fine pores or recesses of the oxide film, or the iodine compound may be electrodeposited into the fine pores or recesses of the oxide film.

[0032] The iodine impregnation treatment in step P3 is carried out by applying an electrolysis voltage of 30 V to 110 V to a solution of iodine or an iodine compound in which the iodine content is 1.0 wt % to 5.0 wt %, for an electrolysis time of 1 minute to 5 minutes.

[0033] The sealing treatment in step P4 is a process for sealing minute pores or recesses in the oxide film after the iodine impregnation treatment. Typical types of sealing treatments include pressurized steam sealing, boiling water sealing, and nickel salt sealing, but pressurized steam sealing is not used. This is because tests have confirmed that pressurized steam sealing causes iodine to leak from minute pores or recesses in the oxide film, resulting in unevenness.

[0034] When sealing is performed using a method other than pressurized steam sealing, the fine pores or recesses in the oxide film are not completely blocked, but are only partially blocked. The degree to which the fine pores or recesses in the oxide film are blocked is evaluated using the sealing degree as an index. There are several sealing degree tests for determining the sealing degree, such as a dye drop test, a phosphoric acid-chromic acid aqueous solution immersion test, and an admittance measurement test, and the sealing degree value varies depending on the sealing degree test.

[0035] Adopting a sealing method with a high degree of sealing leads to improved corrosion resistance of the oxide film, which is the original purpose of sealing treatment. On the other hand, adopting a sealing method with a low degree of sealing leads to an increase in the amount of iodine leaking from the incompletely sealed fine pores or recesses of the oxide film, leading to improved bactericidal and antibacterial effects of iodine. Therefore, it is possible to select a sealing method according to the properties required of aluminum with a surface treatment film.

[0036] Nickel salt sealing is a sealing treatment that closes fine pores or recesses by immersing an oxide film in a sealing solution whose main component is a nickel salt such as nickel fluoride or nickel acetate. As a typical example, when the sealing treatment is performed in a sealing solution consisting of an aqueous solution of nickel acetate, the temperature of the sealing solution is typically set to 95°C or higher, and the oxide film is immersed in the sealing solution for about 10 to 20 minutes.

[0037] In addition to nickel salts, other metal salts such as cobalt acetate are also known for their sealing. By using nickel salts such as nickel acetate or cobalt salts, the bactericidal and antibacterial effects of nickel or cobalt can be obtained in addition to the bactericidal and antibacterial effects of iodine.

[0038] Boiling water sealing is a sealing process that closes minute pores or recesses by immersing an oxide film in hot water at 80°C or higher, typically 95°C to 100°C. Using boiling water sealing ensures that the aluminum surface treatment film after the sealing process does not contain nickel. Therefore, using boiling water sealing makes it possible to use aluminum with a surface treatment film as a material for medical devices and medical parts that cannot contain nickel, which is suspected to be harmful to the human body.

[0039] Conversely, the sealing degree achieved by metal salt sealing, such as nickel salt sealing, is higher than that achieved by boiling water sealing. Therefore, when emphasis is placed on the corrosion resistance of aluminum having a surface treatment film, metal salt sealing may be used.

[0040] After anodizing and iodine impregnation were performed under the above-mentioned conditions, the sealing degree was measured in an admittance measurement test for each of the cases where only nickel salt sealing was performed and the case where only boiling water sealing was performed. The admittance measurement test is a sealing degree test in which the measured value of admittance of the oxide film is used as the sealing degree. The unit of the measured value of admittance is siemens [S], which is the reciprocal ([S] = [1 / Ω]) of the ohm [Ω], which is the unit of electrical resistance and impedance.

[0041] The results of the admittance measurement test showed that the sealing degree when nickel salt sealing was performed for 5 minutes was 20.0 μS, and the sealing degree when boiling water sealing was performed in 85°C hot water for 5 minutes was 30.0 μS. The smaller the measured value [S] of the sealing degree measured by the admittance measurement test, the higher the sealing degree [%]. For example, when pressurized steam sealing was performed, which achieves the highest sealing degree, the sealing degree reached nearly 0 μS. Therefore, the results of the admittance measurement test also confirm that the sealing degree [%] by nickel salt sealing is higher than the sealing degree [%] by boiling water sealing.

[0042] A two-stage sealing process is also known, in which different sealing processes are performed twice. Therefore, when it is particularly desired to improve the sealing degree and corrosion resistance, metal salt sealing such as nickel acetate sealing may be performed first, followed by boiling water sealing.

[0043] After the sealing treatment in step P4 is completed, the surface of the oxide film is washed with pure water, and then air-dried or hot-air-dried in the subsequent step P5.

[0044] Next, the detailed structure of the aluminum having the surface treatment film produced by the above-mentioned production method will be described.

[0045] FIG. 2 is a schematic diagram showing the detailed structure of the aluminum 2 having the surface treatment film 1 produced by the production method shown in FIG.

[0046] As shown in Fig. 2, a surface treatment film 1 is formed on the surface of aluminum 2, which is a base material. The surface treatment film 1 has a structure including an oxide film 4 having fine pores or recesses 3, iodine or an iodine compound 5 impregnated in the fine pores or recesses 3, and a sealing layer 6 deposited near the openings of the fine pores or recesses 3.

[0047] Typically, as illustrated in Fig. 2, it is believed that numerous fine blind pores 3 are formed in the oxide coating 4, each having a U-shaped cross section and with its central axis and depth direction generally perpendicular to the surface of the oxide coating 4. Iodine or an iodine compound 5 is believed to precipitate on the inner surface of the blind pores 3. On the other hand, it is believed that most of the sealing layer 6 is precipitated from the inner surface of the blind pores 3 toward the central axis of the blind pores 3, mainly near the openings of the blind pores 3.

[0048] However, depending on the conditions of the anodizing treatment, it is considered that a large number of fine recesses may be formed in the oxide film 4, each of which has a V-shaped cross section and whose central axis and depth direction are generally perpendicular to the surface of the oxide film 4. Even in this case, it is considered that the iodine or iodine compound 5 is precipitated on the inner surface of the recess, and most of the sealing layer 6 is precipitated from the inner surface of the recess toward the central axis of the recess, mainly near the opening of the recess.

[0049] Even if the oxide coating 4 is subjected to a sealing treatment, the degree of sealing will not be 100% unless pressurized steam sealing is performed. That is, the oxide coating 4 is not completely sealed, but remains partially sealed. Specifically, the minute pores or recesses 3 are incompletely closed by the sealing layer 6. In other words, minute gaps narrower than the openings of the minute pores or recesses 3 remain in the sealing layer 6, and the size of the minute gaps depends on the degree of sealing.

[0050] Therefore, iodine or iodine compounds 5 pass through the minute gaps in the sealing layer 6 and diffuse to the outside of the surface treatment film 1. As a result, iodine or iodine compounds 5 leaking from the minute holes or recesses 3 can provide bactericidal and antibacterial effects. Therefore, aluminum 2 having a surface treatment film 1 can be used to form at least a part of a container such as a vessel or box. In other words, aluminum 2 having a surface treatment film 1 can be used as a material for the container.

[0051] The composition of the sealing layer 6 varies depending on the type of sealing treatment. For example, when nickel salt sealing is performed, nickel and / or nickel salt are precipitated as the sealing layer 6. On the other hand, when boiling water sealing is performed, boehmite (Al2O3·H2O) is formed as the sealing layer 6.

[0052] (effect) FIG. 3 is a table showing the relationship between the temperature of the electrolyte in the anodizing treatment shown in FIG. 1 and the state of the surface treatment film.

[0053] The table in Figure 3 shows the state of the surface treatment film when aluminum is anodized in a 20 wt% sulfuric acid solution to form an oxide film 30 μm thick, and then iodine is electrophoretically deposited by applying a voltage for 3 minutes to a PVPI solution containing 3.0 wt% iodine.

[0054] As shown in the table in Figure 3, the electrolyte temperature during the anodizing treatment (primary electrolysis) and the electrolysis voltage during the electrophoretic deposition of iodine (secondary electrolysis) were varied to examine the state of the oxide film, the state of iodine deposition, and the amount of iodine deposited. More specifically, the electrolyte temperature during the anodizing treatment was varied from 5°C to 30°C in 5°C increments. Meanwhile, the electrolysis voltage during the electrophoretic deposition was set to 30V, 50V, 80V, and 100V. In the table in Figure 3, ◯ indicates good quality, △ indicates quality within the acceptable range, and × indicates quality outside the acceptable range.

[0055] Surface treatment tests revealed that excessive amounts of iodine are deposited by electrophoretic deposition when the temperature of the anodizing electrolyte exceeds 15°C. Furthermore, it was found that excessive iodine deposition results in undesirable iodine deposition conditions, such as unevenness. Excessive iodine deposition results in the color and odor of iodine being transferred to objects that come into contact with or are brought close to the surface of the surface treatment film.

[0056] Therefore, when anodizing is performed to form an oxide film having a thickness of 10 μm to 50 μm in a sulfuric acid electrolyte solution with a sulfuric acid concentration of 15 wt% to 25 wt%, excessive iodine deposition can be avoided by setting the electrolysis temperature to 5°C to 15°C. As a result, the color and odor of iodine can be prevented from adhering to objects that come into contact with or are close to the surface of the surface treatment film. This is thought to be the same when iodine compounds are deposited.

[0057] Furthermore, as shown in the table of Fig. 3, when the electrolysis temperature for anodizing treatment is set to 5°C or higher and 15°C or lower, it was found that the appropriate range of electrolysis voltage when performing electrophoretic deposition of iodine as iodine impregnation treatment is 30V or higher and 110V or lower in order to avoid excessive deposition of iodine. This is also thought to be true when iodine compounds are deposited.

[0058] FIG. 4 is a table showing the relationship between the current application time, the sealing method, and the state of the surface treatment film in the iodine impregnation treatment shown in FIG.

[0059] The table in Figure 4 shows the state of the surface treatment film when aluminum is anodized in a 20 wt% sulfuric acid solution at a liquid temperature of 10°C to form an oxide film 30 μm thick, and then iodine is electrophoretically deposited by applying a voltage of 100 V to a PVPI solution containing 3.0 wt% iodine.

[0060] As shown in the table in Figure 4, the state of the surface treatment film was examined by changing the current application time during the electrophoretic deposition of iodine, which is performed as secondary electrolysis, and the sealing method after the electrophoretic deposition of iodine. More specifically, the current application time during the electrophoretic deposition of iodine was set to 1 minute, 3 minutes, 5 minutes, and 10 minutes. Meanwhile, the state of the surface treatment film was examined by performing sealing treatments using nickel salt, boiling water sealing using hot water at 85°C, and warm water sealing using warm water at 75°C, as well as when no sealing treatment was performed.

[0061] The condition of the surface-treated film was evaluated by the color tone or appearance of the film surface immediately after electrophoretic deposition of iodine and before sealing, as well as the subsequent iodine elution state, degree of powdering, degree of discoloration, and degree of iodine odor after sealing or without sealing. In the table of Figure 4, ◯ indicates good quality, △ indicates quality within the acceptable range, and × indicates quality outside the acceptable range. The evaluation results for the unsealed cases represent the evaluation results after washing with pure water at room temperature to remove impurities.

[0062] As a result of the surface treatment test, even if the electrolysis time during electrophoretic deposition of iodine was extended beyond 5 minutes, no increase in the amount of effective iodine deposition was confirmed. In other words, even if a voltage of 100 V was applied to a PVPI solution for more than 5 minutes, no change in color due to iodine was confirmed, and only an increase in the excess deposition of iodine was observed.

[0063] Therefore, when electrophoretic deposition of iodine or iodine compounds is performed as an iodine impregnation treatment by applying an electrolysis voltage of 30 V to 110 V to a solution of iodine or iodine compounds containing 1.0 wt% to 5.0% iodine, applying the electrolysis voltage for an electrolysis time of 1 minute to 5 minutes is appropriate from the viewpoint of avoiding excessive iodine deposition. In other words, if the current application time for the secondary electrolysis treatment is set to 1 minute to 5 minutes, it is possible to avoid or reduce the transfer of the color and odor of iodine to objects that come into contact with or are brought close to the surface of the surface treatment film. This is thought to be the same when iodine compounds are deposited.

[0064] On the other hand, with regard to the sealing method, the surface treatment state changes when the sealing conditions, such as the type of nickel salt, sealing time, and sealing temperature, are changed. That is, the table in Figure 4 shows the results of a surface treatment test when sealing is performed under certain sealing conditions and sealing methods. For this reason, depending on the sealing conditions, the surface treatment test results exemplified in the table in Figure 4 will not necessarily be obtained. Therefore, by determining an appropriate sealing method and sealing conditions that correspond to the required quality, it is possible to produce aluminum with a surface treatment film that meets the required quality.

[0065] As described above, by appropriately setting the conditions for the anodization of aluminum as the primary electrolytic treatment and the electrophoretic deposition of iodine or iodine compounds as the secondary electrolytic treatment as shown in Figure 1, it is possible to reduce the brown discoloration and odor characteristic of iodine or iodine compounds. As a result, it is possible to reduce or avoid the attachment of color and odor to objects while still achieving the bactericidal and antibacterial effects of iodine or iodine compounds.

[0066] Furthermore, aluminum having a surface treatment film produced by the above-mentioned manufacturing method can be used as a material for containers such as vessels and boxes in which transfer of color or odor to stored items must be avoided. In other words, when a container is made of aluminum having a surface treatment film produced by the above-mentioned manufacturing method, it is possible to reduce or avoid transfer of color or odor from the container to objects stored in the container.

[0067] (Second embodiment) FIG. 5 is a flowchart showing the steps of a method for producing aluminum having a surface treatment film according to a second embodiment of the present invention.

[0068] 5 differs from the method for producing aluminum having a surface treatment film in the first embodiment in that the conditions for the anodizing treatment and the iodine impregnation treatment are not limited, and the sealing treatment is limited to hot water sealing. The other steps in the method for producing aluminum having a surface treatment film in the second embodiment are not substantially different from the method for producing aluminum having a surface treatment film in the first embodiment, and therefore the same steps are designated by the same reference numerals and their explanations are omitted.

[0069] In step P2' of the second embodiment, anodizing treatment is performed in the same manner as in step P2 of the first embodiment, but anodizing treatment may be performed in an acidic aqueous solution such as chromic acid, phosphoric acid, or oxalic acid in addition to sulfuric acid. Therefore, the electrolytic treatment conditions may be changed as appropriate. However, if anodizing treatment of aluminum is performed under the same electrolytic treatment conditions as in step P2 of the first embodiment, it is possible to more effectively prevent or reduce the transfer of the color and odor of iodine to objects that come into contact with or are brought close to the surface of the surface treatment film.

[0070] In step P3' of the second embodiment, iodine impregnation is performed in the same manner as in step P3 of the first embodiment, but the method is not limited to electrophoretic deposition of iodine or an iodine compound, and the iodine impregnation may be performed by immersion in a solution containing PVPI such as iodine or an iodine compound. However, if electrophoretic deposition of iodine or an iodine compound is performed under electrolytic treatment conditions similar to those in step P3 of the first embodiment, it is possible to more effectively prevent or reduce the transfer of the color and odor of iodine to objects that come into contact with or are brought close to the surface of the surface treatment film.

[0071] In step P4' of the second embodiment, a pore sealing treatment is performed similarly to step P4 of the first embodiment, but hot water sealing is performed as the pore sealing treatment. Hot water sealing is a pore sealing treatment using hot water at 60°C or higher and lower than 80°C.

[0072] Like boiling water sealing, hot water sealing is a sealing process that does not use metal salts such as nickel salts or cobalt salts, and therefore, hot water sealing can ensure safety to the human body. In other words, aluminum with a surface treatment film can be made nickel-free. As a result, aluminum with a surface treatment film can be used as a material for medical instruments and containers, which require safety to the human body.

[0073] As a result of the surface treatment test, as shown in the table of FIG. 4 mentioned in the first embodiment, it was found that when boiling water sealing is performed as the sealing treatment, depending on the conditions of the electrophoretic deposition of iodine or an iodine compound, iodine, which is a bactericidal and antibacterial component, may be eluted, resulting in an appearance that is not uniform or in the deposition of powdery substances.

[0074] In contrast, as shown in the table in Figure 4, it has been found that hot water sealing not only avoids the problems of uneven appearance and powdering that occur when boiling water sealing is used, but also makes it difficult for the color and odor of iodine or iodine compounds to disappear. Therefore, although the sealing degree of hot water sealing is smaller than that of boiling water sealing, hot water sealing not only reduces uneven appearance and powder deposition, but also prevents or reduces the transfer of the color and odor of iodine or iodine compounds to objects that come into contact with or near the surface of the surface treatment film. In short, hot water sealing can be said to be a sealing treatment that is compatible with iodine impregnation treatment.

[0075] FIG. 6 is a table comparing the state of the surface treatment film after hot water sealing shown in FIG. 5 with the state of the surface treatment film after other sealing treatments.

[0076] The table in Figure 6 shows an example in which aluminum is anodized in a 20 wt% sulfuric acid solution at 10°C in step P2' to form an oxide film 30 μm thick, and then in step P3' a voltage of 100 V is applied for 3 minutes to a PVPI solution containing 3.0 wt% iodine to perform electrophoretic deposition of iodine, followed by hot water sealing in step P4'. The state of the surface treatment film is compared with that in cases where boiling water sealing and nickel salt sealing are performed.

[0077] More specifically, as shown in the table of Figure 6, boiling water sealing using 90°C hot water, boiling water sealing using 85°C hot water, boiling water sealing using 80°C hot water, hot water sealing using 75°C hot water, and nickel salt sealing were performed, and the condition of the surface treatment film was examined. The condition of the surface treatment film was evaluated by the state of iodine elution, the degree of powdering, the degree of discoloration, and the degree of iodine odor after 12 hours. In the table of Figure 6, ◯ indicates good quality, △ indicates quality within the acceptable range, and × indicates quality outside the acceptable range.

[0078] As shown in the table in Figure 6, surface treatment tests, including sealing tests, showed that nickel salt sealing and boiling water sealing using hot water at 85°C or higher resulted in powdery coating. It was also found that the lower the temperature of the pure water used in the sealing treatment, the more effectively the iodine odor was reduced. This means that even if the degree of sealing of the oxide film is low, the amount of leakage of the color and odor of iodine or iodine compounds does not increase appreciably. However, if the temperature of the pure water is too low, the degree of sealing will decrease, and there is a risk that the original purpose of the sealing treatment, which is to provide corrosion resistance to the aluminum alloy by the oxide film, will be insufficient.

[0079] Therefore, although a sealing treatment using hot water at 60° C. or higher but lower than 80° C. is classified as hot water sealing, from the viewpoint of ensuring the corrosion resistance of the aluminum alloy while suppressing the diffusion of the color and odor of iodine or iodine compounds, it is considered that the preferable temperature range of the hot water is 70° C. or higher but 75° C. In other words, if hot water sealing is performed using hot water at 70° C. or higher but 75° C., it is possible to more effectively prevent or reduce the transfer of the color and odor of iodine to objects that come into contact with or near the surface of the surface treatment film while ensuring the corrosion resistance of the aluminum alloy.

[0080] FIG. 7 is a table showing the relationship between the hot water sealing treatment time shown in FIG. 5 and the state of the surface treatment film.

[0081] The table in Figure 7 shows the state of the surface treatment film obtained when, in step P2', aluminum is anodized in a sulfuric acid solution with a concentration of 20 wt% at a liquid temperature of 10°C to form an oxide film with a thickness of 30 μm, and then, in step P3', a voltage of 100 V is applied for 3 minutes to a PVPI solution with an iodine content of 3.0 wt% to perform electrophoretic deposition of iodine, and then, in step P4', hot water sealing is performed using hot water at 75°C.

[0082] As shown in the table of Figure 7, surface treatment tests including sealing tests were conducted by varying the hot water sealing treatment time. More specifically, as shown in the table of Figure 7, the condition of the surface treatment film was examined by changing the hot water sealing treatment time to 10 minutes, 5 minutes, 1 minute, and 10 seconds. The condition of the surface treatment film was evaluated by the state of iodine elution, the degree of powdering, the degree of discoloration, and the degree of iodine odor after 12 hours. In the table of Figure 7, ◯ indicates good quality, △ indicates quality within the acceptable range, and × indicates quality outside the acceptable range.

[0083] As shown in the table in Figure 7, the results of the surface treatment test, including the sealing test, showed that powdering occurred when the hot water sealing treatment time was 10 minutes. It was also confirmed that a hot water sealing treatment time of 5 minutes was able to minimize the elution of iodine, iodine discoloration, and iodine odor that cause uneven appearance.

[0084] Therefore, from the viewpoint of reducing the odor of iodine or iodine compounds while avoiding powdering, a preferable range of hot water sealing treatment time is considered to be from 3 to 7 minutes. In other words, if hot water sealing is performed as the sealing treatment and the hot water sealing treatment time is from 3 to 7 minutes, it is possible to avoid powdering, a typical problem in anodizing, while more effectively avoiding or reducing the adhesion of the odor of iodine to objects that come into contact with or near the surface of the surface treatment film.

[0085] When hot water sealing is used as the sealing treatment, bayerite (Al2O3·3H2O) precipitates on the surface of the oxide film, including the fine pores or recesses. That is, in aluminum 2 having a surface treatment film 1 shown in Figure 2, the sealing layer 6 has a bayerite composition. More specifically, it is thought that the sealing layer 6, which is a bayerite layer, grows from the oxide film 4, which is an aluminum oxide layer, near the opening of the fine pores or recesses 3 toward the center of the fine pores or recesses 3.

[0086] Therefore, if boehmite is not precipitated in the surface treatment film 1 but bayerite is, then hot water sealing, not boiling water sealing, has been performed as the sealing treatment. Also, if bayerite is precipitated in the surface treatment film 1 and a metal such as nickel is not contained as an element, then metal salt sealing as the two-step sealing has not been performed.

[0087] However, it is not easy to directly determine whether bayerite or boehmite has precipitated in a surface treatment film, so a method is usually employed to indirectly determine whether bayerite or boehmite has precipitated in a surface treatment film by measuring the sealing degree of the oxide film.

[0088] When boehmite is precipitated on the surface of the oxide film due to boiling water sealing, the degree of sealing measured by the admittance measurement test is thought to be approximately 30.0 μS, as described in the first embodiment. The degree of sealing is thought to vary depending on the sealing conditions, such as the sealing time and the temperature of the hot water.

[0089] In contrast, when bayerite is precipitated on the surface of the oxide film due to hot water sealing, the sealing degree measured by the admittance measurement test is thought to be in the range of approximately 40 μS to 60 μS, depending on sealing conditions such as the sealing time and the hot water temperature. Therefore, if the sealing degree of the oxide film measured by the admittance measurement test is 40 μS to 60 μS, it is thought that bayerite has precipitated on the surface of the oxide film due to hot water sealing. In fact, when hot water sealing was performed for 5 minutes using 75°C hot water, the sealing degree of the oxide film was measured in the admittance measurement test and was found to be 50 μS.

[0090] As described above, in the first embodiment, the electrolytic treatment conditions for the anodizing treatment and the iodine impregnation treatment are determined so that the color and odor of iodine or iodine compounds are hard to remove, whereas in the second embodiment, the conditions for the sealing treatment are determined so that the color and odor of iodine or iodine compounds are hard to remove.

[0091] Therefore, according to the second embodiment, like the first embodiment, it is possible to reduce or avoid the attachment of color and odor to an object while still achieving the bactericidal and antibacterial effects of iodine or an iodine compound. In addition, according to the second embodiment, safety to the human body can be ensured by making the aluminum having the surface treatment film nickel-free, etc. Therefore, it is possible to use aluminum having a surface treatment film as a material for medical instruments and containers that require safety to the human body.

[0092] Of course, the first and second embodiments may be combined. That is, not only are the electrolytic treatment conditions for the aluminum anodizing treatment performed as the primary electrolytic treatment and the electrophoretic deposition of iodine or iodine compounds performed as the secondary electrolytic treatment appropriately set, but also the sealing treatment may be performed using hot water, thereby making it difficult for the color and odor of iodine or iodine compounds to adhere to the object.

[0093] (Third embodiment) FIG. 8 is a flowchart showing the steps of a method for producing aluminum having a surface treatment film according to a third embodiment of the present invention.

[0094] The method for producing aluminum having a surface treatment film according to the third embodiment shown in Figure 8 differs from the method for producing aluminum having a surface treatment film according to the second embodiment in that, after the iodine impregnation treatment, a decolorizing and deodorizing treatment that also serves as drying is performed without performing a sealing treatment of the oxide film. The other steps in the method for producing aluminum having a surface treatment film according to the third embodiment are not substantially different from those in the method for producing aluminum having a surface treatment film according to the second embodiment, and therefore the same steps are designated by the same reference numerals and their explanations are omitted.

[0095] 8, in step P10 after the iodine impregnation treatment in step P3′, a decolorizing and deodorizing treatment is performed to reduce the diffusion of the color and odor of iodine or iodine compounds to a negligible level. The decolorizing and deodorizing treatment can be a treatment in which iodine or iodine compounds impregnated into minute pores or recesses of an oxide film are exposed to air, thereby diffusing the iodine or iodine compounds into the air.

[0096] Test results showed that exposing the surface of an oxide film to air at room temperature for 24 hours or more did not result in any significant improvement in the deodorizing and decolorizing effects of iodine or iodine compounds. Therefore, the decolorizing and deodorizing treatment can be a treatment in which iodine or an iodine compound impregnated into the fine pores or recesses of the oxide film is exposed to air for 24 hours or more. However, the decolorizing and deodorizing treatment may be replaced by another treatment or may be used in combination with another treatment. Furthermore, the decolorizing and deodorizing treatment is not limited to being performed at room temperature. At least a part of the decolorizing and deodorizing treatment may also serve as hot air drying by using hot air.

[0097] When bleaching and deodorizing is performed, the iodine or iodine compounds are dispersed into the atmosphere to the extent that their color and odor are not lost, as shown in the table in Figure 4. In addition, problems such as iodine elution and powdering, which can cause uneven appearance, do not occur.

[0098] The color of the surface treatment film immediately after the iodine impregnation treatment depends on the conditions of the iodine impregnation treatment, as shown in the table in Figure 4. However, the color of the surface treatment film after the bleaching and deodorizing treatment becomes light orange or yellow. Typically, the color of the surface treatment film gradually changes from brown to yellow after the bleaching and deodorizing treatment. As a result, the color of the aluminum with the surface treatment film becomes close to gold due to the metallic luster of the aluminum base material.

[0099] As can be seen from the appearance, even after bleaching and deodorizing treatment, a thin layer of iodine or iodine compounds remains on the inner surfaces of the minute pores or recesses in the oxide film, which allows the bactericidal and antibacterial effects of iodine or iodine compounds to be maintained.

[0100] Therefore, according to the third embodiment, it is possible to further reduce or more reliably prevent the color and odor of iodine or iodine compounds from fading and adhering to objects while maintaining the bactericidal and antibacterial effects of iodine or iodine compounds. In addition, it is possible to obtain an appearance close to gold.

[0101] Furthermore, if the decolorizing and deodorizing treatment is performed in step P10, even if the iodine impregnation treatment in step P3' results in excessive precipitation of iodine or iodine compounds or causes uneven appearance due to iodine elution, the iodine or iodine compounds will fall off from the oxide film in the subsequent decolorizing and deodorizing treatment.

[0102] Therefore, strictly speaking, unlike the second embodiment, in the third embodiment, it is not important to optimize the treatment conditions for avoiding excessive deposition of iodine or iodine compounds or elution of iodine in the anodizing treatment in step P2' and the iodine impregnation treatment in step P3'. For example, it is not important in the third embodiment to determine the electrolytic treatment conditions for the anodizing treatment and the iodine impregnation treatment so as to make it difficult for the color and odor of iodine or iodine compounds to be removed, as in the first embodiment.

[0103] (Fourth embodiment) FIG. 9 is a flowchart showing the steps of a method for producing aluminum having a surface treatment film according to a fourth embodiment of the present invention.

[0104] The method for producing aluminum having a surface treatment film according to the fourth embodiment shown in FIG. 9 differs from the method for producing aluminum having a surface treatment film according to the third embodiment in that a sealing treatment and drying are performed after a bleaching and deodorizing treatment. The steps up to the bleaching and deodorizing treatment in the method for producing aluminum having a surface treatment film according to the fourth embodiment are substantially the same as those in the method for producing aluminum having a surface treatment film according to the third embodiment. Furthermore, the drying performed in the method for producing aluminum having a surface treatment film according to the fourth embodiment is substantially the same as that in the method for producing aluminum having a surface treatment film according to the first embodiment. For this reason, in the fourth embodiment, steps that are the same as those in the first or third embodiment are designated by the same reference numerals, and descriptions thereof will be omitted.

[0105] As shown in FIG. 9, after the decolorizing and deodorizing treatment in step P10, a step P4" for sealing the pores in the oxide film may be carried out. In this case, a step P5 for drying is provided after the sealing treatment in step P4".

[0106] When the oxide film is sealed after the decolorization and deodorization treatment, the deodorization and decolorization of the iodine or iodine compound has already been completed to the extent that the color and odor of the iodine or iodine compound are no longer present on the object before the oxide film is sealed. Therefore, unlike the first embodiment, there are no restrictions on the sealing treatment conditions that would make it difficult for the color and odor of the iodine or iodine compound to fade. This allows the sealing treatment to be performed under desired sealing conditions for the purpose of improving the corrosion resistance of the surface treatment film, etc.

[0107] For example, aluminum having a nickel-free surface treatment film can be produced by boiling water sealing or hot water sealing. In particular, boiling water sealing can improve the degree of sealing compared to hot water sealing, thereby improving the corrosion resistance of the surface treatment film.

[0108] Needless to say, the sealing treatment of the oxide film, which is carried out after the bleaching and deodorizing treatment, should be carried out before the oxide film corrodes.

[0109] According to the fourth embodiment described above, the bactericidal and antibacterial effects of iodine or iodine compounds can be maintained while further reducing or more reliably preventing the color and odor of iodine or iodine compounds from being lost and adhering to objects, and the sealing treatment can impart corrosion resistance to the surface treatment film. In addition, by providing a decolorizing and deodorizing step that removes the color and odor of iodine or iodine compounds, it is possible to avoid restrictions on the treatment conditions for anodizing, iodine impregnation, and sealing, which are required to avoid excessive deposition of iodine or iodine compounds or elution of iodine. [Example]

[0110] Example 1 The primary electrolysis process involved anodizing aluminum in a sulfuric acid solution with a sulfuric acid concentration of 20 wt% and an electrolytic bath temperature of 10°C, resulting in aluminum with an oxide film 30 μm thick. Next, the secondary electrolysis process involved electrophoretic deposition of iodine in a PVPI solution with an iodine content of 3.0%. The electrolysis voltage for the secondary electrolysis process was 100 V, the electrolysis time for the secondary electrolysis process was 3 minutes, and the electrolytic bath temperature for the secondary electrolysis process was room temperature.

[0111] Thereafter, nickel salt sealing was performed by immersing the aluminum in a sealing solution containing nickel acetate as the main component for 1 minute, and then drying, thereby producing aluminum having a surface treatment film of Example 1 according to the manufacturing method of the first embodiment.

[0112] Example 2 Anodizing treatment of aluminum and electrophoretic deposition of iodine were carried out under the same conditions as in Example 1. After that, hot water sealing was carried out using hot water at 70°C for 5 minutes, and then drying was carried out to produce aluminum having a surface treatment film of Example 2 using the manufacturing method of the second embodiment.

[0113] Example 3 Anodizing treatment of aluminum and electrophoretic deposition of iodine were carried out under the same conditions as in Example 1. After that, the aluminum was simply washed with pure water without sealing, and exposed to air for 24 hours or more to decolorize and deodorize the iodine, thereby producing aluminum having a surface treatment film of Example 3 using the manufacturing method of the third embodiment.

[0114] (Comparative Example 1) Anodizing treatment of aluminum and electrophoretic deposition of iodine were carried out under the same conditions as in Example 1. Then, boiling water sealing was carried out for 5 minutes using hot water at 85°C as shown in the table in Figure 6, and then drying was carried out to produce aluminum having the powdery surface treatment film of Comparative Example 1.

[0115] (Other embodiments) Although specific embodiments have been described above, the described embodiments are merely examples and do not limit the scope of the invention. The novel methods and apparatus described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and modifications may be made in the forms of the methods and apparatus described herein without departing from the spirit of the invention. The appended claims and their equivalents include all such forms and modifications as fall within the scope and spirit of the invention. [Explanation of symbols]

[0116] 1. Surface treatment film 2. Aluminum 3. Microscopic holes or recesses 4. Oxide film 5 Iodine or iodine compounds 6 Sealing layer

Claims

1. Anodizing treatment for forming an oxide film having fine holes or recesses on the surface of aluminum; an iodine impregnation treatment for impregnating the fine holes or recesses of the oxide coating with iodine or an iodine compound by electrophoretic deposition of the iodine or an iodine compound; a sealing treatment of the oxide film after the iodine impregnation treatment; and A method for producing aluminum having a surface treatment film, comprising the steps of: In the anodizing treatment, forming an oxide film having a thickness of 10 μm to 50 μm in an electrolytic solution of sulfuric acid having a temperature of 5° C. to 15° C. and a sulfuric acid concentration of 15 wt % to 25 wt %, In the iodine impregnation treatment, applying an electrolysis voltage of 30 V to 110 V for 1 minute to 5 minutes to the solution of iodine or an iodine compound having an iodine content of 1.0 wt % to 5.0 wt %; A method for producing aluminum having a surface treatment film.

2. 2. The method for producing aluminum having a surface treatment film according to claim 1, wherein the sealing treatment is performed by using hot water at a temperature of 60° C. or higher and lower than 80° C.

3. Anodizing treatment for forming an oxide film having fine holes or recesses on the surface of aluminum; an iodine impregnation treatment for impregnating the fine holes or recesses of the oxide coating with iodine or an iodine compound; a sealing treatment of the oxide film after the iodine impregnation treatment; and A method for producing aluminum having a surface treatment film, comprising the steps of: The method for producing aluminum having a surface treatment film comprises carrying out hot water sealing using hot water at a temperature of 60° C. or higher and lower than 80° C. as the sealing treatment.

4. 4. The method for producing aluminum having a surface treatment film according to claim 3, wherein the sealing treatment is performed by using hot water at a temperature of 70° C. or higher but not higher than 75° C.

5. The method for producing aluminum having a surface treatment film according to any one of claims 2 to 4, wherein the hot water sealing treatment time is from 3 minutes to 7 minutes.

6. Anodizing treatment for forming an oxide film having fine holes or recesses on the surface of aluminum; an iodine impregnation treatment for impregnating the fine holes or recesses of the oxide coating with iodine or an iodine compound; a decolorizing and deodorizing treatment for reducing the diffusion of the color and odor of the iodine or iodine compound after the iodine impregnation treatment; A method for producing aluminum having a surface treatment film, comprising the steps of:

7. 7. The method for producing aluminum having a surface treatment film according to claim 6, wherein the decolorizing and deodorizing treatment is a treatment in which the iodine or iodine compound impregnated in the fine pores or recesses is exposed to air for 24 hours or more.

8. The method for producing aluminum having a surface treatment film according to claim 6 or 7, wherein the oxide film is not subjected to a sealing treatment.

9. 8. The method for producing aluminum having a surface treatment film according to claim 6, further comprising the step of sealing the oxide film after the decolorizing and deodorizing treatment.

10. Aluminum having a surface treatment film, The surface treatment film is An oxide film having fine holes or recesses; Iodine or an iodine compound impregnated in the fine holes or recesses; having The aluminum has a sealing degree of 40 μS or more and 60 μS or less as measured by an admittance measurement test of the oxide film.

11. Aluminum having a surface treatment film, The surface treatment film is An oxide film having fine holes or recesses; Iodine or an iodine compound impregnated in the fine holes or recesses; Bayerite precipitated in the fine holes or recesses; Aluminum having

12. The aluminum according to claim 10 or 11, wherein the surface treatment film does not contain nickel as an element.

13. The aluminum according to claim 10 or 11, wherein the surface treatment film does not contain precipitated boehmite.

14. A container at least a part of which is made of aluminum having the surface treatment film according to claim 10 or 11.

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