Aluminum member, method for producing same, and container

Abstract

An aluminum member (1) has: a base material (2) comprising aluminum or an aluminum alloy; an oxide layer (3) that comprises an oxide of aluminum and is formed on the base material (2); a hydrated oxide layer (4) that contains a hydrated oxide of aluminum and is formed on the oxide layer (3); and a transparent film (5) formed on the hydrated oxide layer (4). When the aluminum member (1) is heated at a temperature of 200°C for 30 minutes, cracks do not form in the oxide layer (3) or the hydrated oxide layer (4).

Description

Aluminum member, method for producing the same, and container

[0001] The present invention relates to an aluminum member, a method for producing the same, and a container.

[0002] Aluminum materials made of aluminum or aluminum alloys are used in various applications. An anodic oxidation film may be provided on the surface of these aluminum materials in order to achieve various purposes such as improving corrosion resistance, improving scratch resistance, and improving design. Further, a transparent film may be formed on the anodic oxidation film.

[0003] For example, Patent Document 1 describes a method for producing an aluminum coating material, which includes an anodic oxidation treatment step of forming an anodic oxidation film by subjecting the surface of an aluminum base material to anodic oxidation treatment, and a coating step of applying a coating composition containing a transparent resin and a silane coupling agent to the surface of the anodic oxidation film to form a transparent coating film. Further, Patent Document 1 describes performing a sealing treatment of the anodic oxidation film following the anodic oxidation treatment step and then performing the coating step.

[0004] Japanese Unexamined Patent Application Publication No. 2017-008338

[0005] However, the aluminum coating material of Patent Document 1 has a problem that cracks occur in the anodic oxidation film when its temperature rises for some reason, and the appearance is easily damaged.

[0006] The present invention has been made in view of such a background, and an aluminum member, a method for producing the same, and a container made of this aluminum member, which can maintain a good appearance even when the temperature rises, are provided.

[0007] One aspect of the present invention is an aluminum member having a base material made of aluminum or an aluminum alloy, an oxide layer made of aluminum oxide formed on the base material, a hydrated oxide layer containing hydrated aluminum oxide formed on the oxide layer, and a transparent film formed on the hydrated oxide layer, wherein no cracks are formed in the oxide layer and the hydrated oxide layer when the aluminum member is heated at a temperature of 200°C for 30 minutes.

[0008] Another aspect of the present invention is a container made of an aluminum member according to the above-described aspect.

[0009] A further aspect of the present invention relates to a method for manufacturing an aluminum member, comprising: applying an anodic oxidation treatment to a base material made of aluminum or an aluminum alloy to form an oxide layer made of aluminum oxide on the base material; heating the oxide layer at a temperature of 200°C to 400°C; then hydrating the aluminum oxide constituting the oxide layer to form a hydrated oxide layer containing hydrated aluminum oxide on the oxide layer; and forming a transparent film on the hydrated oxide layer.

[0010] In the aforementioned aluminum component, an oxide layer, a hydrated oxide layer, and a transparent film are laminated in this order on the base material. Furthermore, the aluminum component has the property that no cracks are formed in the oxide layer and the hydrated oxide layer when heated at a temperature of 200°C for 30 minutes. By providing the oxide layer and hydrated oxide layer configured in this way on the base material, the aluminum component can suppress the occurrence of cracks in the oxide layer and hydrated oxide layer even when the temperature rises for any reason, and maintain a good appearance.

[0011] Furthermore, in the method for manufacturing the aluminum member, after forming an oxide layer on the base material, the oxide layer is heated to a temperature within the specified range. By heating the oxide layer on the base material in this way, the internal stress generated during the formation of the oxide layer can be relieved. Then, a hydrated oxide layer is formed on the oxide layer after the internal stress has been relieved, and a transparent film is further formed on the hydrated oxide layer. This suppresses the occurrence of cracks in the oxide layer and the hydrated oxide layer even if the temperature rises for any reason, and maintains a good appearance.

[0012] As described above, according to the above embodiment, it is possible to provide an aluminum member that can maintain a good appearance even when the temperature rises, a method for manufacturing the same, and a container made of this aluminum member.

[0013] Figure 1 is a cross-sectional view of the aluminum member in Example 1. Figure 2 is a cross-sectional view of the base material in the state in which the oxide layer has been formed in the manufacturing method of the aluminum member in Example 1. Figure 3 is a cross-sectional view of the base material in the state in which the hydrated oxide layer has been formed in the manufacturing method of the aluminum member in Example 1. Figure 4 is a magnified photograph of test material A10 in Example 1. Figure 5 is a magnified photograph of test material B7 in Example 1.

[0014] (Aluminum Member) The aluminum member has the property that no cracks will occur in the oxide layer and hydrated oxide layer when heated at a temperature of 200°C for 30 minutes. In this specification, "crack" refers to a crack of a size that affects the appearance of the aluminum member. Furthermore, the state of "no cracks being formed in the oxide layer and hydrated oxide layer" includes a state in which no cracks are formed at all in the oxide layer and hydrated oxide layer, and a state in which minute cracks that do not affect the appearance of the aluminum member are formed in the oxide layer and hydrated oxide layer.

[0015] Whether or not cracks exist in the oxide layer and / or hydrated oxide layer can be determined based on magnified photographs obtained by observing the surface of the aluminum component using an optical microscope with a magnification of 35x. If cracks are present in the oxide layer and / or hydrated oxide layer in these magnified photographs, it is determined that cracks affecting the appearance of the aluminum component have formed in the oxide layer and / or hydrated oxide layer. On the other hand, if no cracks are present in the oxide layer and / or hydrated oxide layer in the magnified photographs, it is determined that no cracks affecting the appearance of the aluminum component have formed in the oxide layer and / or hydrated oxide layer.

[0016] The base material of the aforementioned aluminum member is made of aluminum or an aluminum alloy. The shape of the base material is not particularly limited and can take various shapes depending on the application of the aluminum member. For example, the base material may be a wrought material such as a rolled plate or an extruded material, or it may be a cast material or a forged material. The base material may also be machined to form a desired shape. If the shape of the base material is a plate, the thickness of the base material is not particularly limited. More specifically, the base material may be a cold-rolled plate with a thickness of about 1 mm, or a hot-rolled plate with a thickness of about 50 mm.

[0017] Furthermore, the material of the base material can be appropriately selected from the group consisting of aluminum and aluminum alloys, depending on the application of the aluminum component. More specifically, for example, 1000 series aluminum can be used as the aluminum constituting the base material. For example, 2000 series aluminum alloy, 3000 series aluminum alloy, 4000 series aluminum alloy, 5000 series aluminum alloy, 6000 series aluminum alloy, 7000 series aluminum alloy, and 8000 series aluminum alloy can be used as the aluminum alloy constituting the base material. The base material may also be a clad material in which two or more layers having different chemical compositions are laminated.

[0018] An oxide layer made of aluminum oxide is provided on the base material. The oxide layer may have pores. That is, the oxide layer may be a porous type anodic oxide film. Alternatively, the oxide layer may be a barrier type anodic oxide film that does not have pores. From the viewpoint of making it easier to increase the thickness of the anodic oxide film, it is preferable that the oxide layer has pores.

[0019] A hydrated oxide layer is provided on the oxide layer. The hydrated oxide layer contains at least aluminum hydrated oxide. That is, the hydrated oxide layer may be composed of aluminum hydrated oxide. Alternatively, the hydrated oxide layer may be composed of aluminum hydrated oxide and oxides and / or hydroxides of metal elements other than aluminum.

[0020] Examples of metal elements included in the hydrated oxide layer include Ni (nickel), Cr (chromium), Zr (zirconium), Si (silicon), Ti (titanium), Au (gold), Ag (silver), Co (cobalt), Mo (molybdenum), Mn (manganese), Nb (niobium), Ta (tantalum), W (tungsten), Zn (zinc), Fe (iron), Ir (iridium), and Sc (scandium). In other words, the hydrated oxide layer may contain a hydrated aluminum oxide and oxides and / or hydroxides of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc.

[0021] Aluminum hydrate oxides and oxides and hydroxides of the aforementioned metal elements have high chemical stability, making them less susceptible to deterioration during use of the aluminum component. Furthermore, aluminum hydrate oxides also exhibit excellent corrosion resistance. Therefore, by providing a hydrate oxide layer containing aluminum hydrate oxide on top of the oxide layer, high corrosion resistance can be maintained for a longer period of time.

[0022] The sum of the thickness of the oxide layer and the thickness of the hydrated oxide layer is preferably 5 μm or more and 100 μm or less. By making the sum of the thickness of the oxide layer and the thickness of the hydrated oxide layer 5 μm or more, the corrosion resistance and dyeability of the aluminum member can be further improved. From the viewpoint of further enhancing this effect, the sum of the thickness of the oxide layer and the thickness of the hydrated oxide layer is more preferably 10 μm or more, and even more preferably 15 μm or more. On the other hand, by making the sum of the thickness of the oxide layer and the thickness of the hydrated oxide layer 100 μm or less, it is easier to avoid an excessive increase in the processing time in the anodizing treatment, and the productivity of the aluminum member can be more easily increased. From the viewpoint of further enhancing this effect, the sum of the thickness of the oxide layer and the thickness of the hydrated oxide layer is more preferably 75 μm or less, and even more preferably 50 μm or less.

[0023] In determining a preferred range for the sum of the thickness of the oxide layer and the thickness of the hydrated oxide layer, the aforementioned upper and lower limits of the sum of the thicknesses can be arbitrarily combined. For example, the preferred range for the sum of the thickness of the oxide layer and the thickness of the hydrated oxide layer may be 10 μm or more and 75 μm or less, or 15 μm or more and 50 μm or less.

[0024] It is preferable that the oxide layer and hydrated oxide layer are free from cracks. By forming crack-free oxide and hydrated oxide layers on the base material in this way, the appearance of the surface-treated aluminum component can be more reliably improved.

[0025] A transparent film is provided on the hydrated oxide. The thickness of the transparent film is preferably 0.1 μm to 50 μm. In this case, the aluminum member with a glossy surface can be obtained more easily.

[0026] The transparent film may be an inorganic transparent film composed of inorganic materials, or an organic transparent film containing an organic resin. Examples of inorganic materials constituting the inorganic transparent film include silicon-containing oxides such as silicon dioxide. Examples of organic resins contained in the organic transparent film include acrylic resin, methacrylic resin, polyester resin, epoxy resin, polyurethane resin, polyolefin resin, and polysulfone resin.

[0027] The transparent coating preferably contains an organic resin. As mentioned above, the oxide layer and hydrated oxide layer of the aluminum member are less prone to cracking even when the temperature of the aluminum member rises. Therefore, even when the transparent coating containing the organic resin is baked at a relatively high temperature during the manufacturing process of the aluminum member, the formation of cracks in the oxide layer and hydrated oxide layer can be easily avoided. Furthermore, by baking the transparent coating at a high temperature, the durability of the transparent coating containing the organic resin can be further enhanced.

[0028] If the organic resin is a polyester resin or an epoxy resin, the mass loss after immersing the transparent film in boiling methyl ethyl ketone for 60 minutes is 1 mg / cm². 2 The following is preferable. Since the transparent film having these characteristics is formed by baking at a relatively high temperature, it has high durability.

[0029] From a similar viewpoint, if the transparent resin is a polypropylene resin, it is preferable that the scratch hardness of the transparent film be H or higher.

[0030] (Container) As mentioned above, the aluminum component is less prone to cracking in the oxide layer and hydrated oxide layer even when its temperature rises, and can easily maintain a good appearance. Furthermore, since the oxide layer, hydrated oxide layer, and transparent film provided on the base material all transmit visible light, the aluminum component has high design appeal that takes advantage of the metallic luster of the base material. For this reason, the aluminum component obtained by the above manufacturing method is suitable for applications that require high design appeal, such as containers.

[0031] (Method for manufacturing aluminum member) The aluminum member is obtained by, for example, anodic oxidation treatment of a base material made of aluminum or an aluminum alloy to form an oxide layer made of aluminum oxide on the base material, heating the oxide layer at a temperature of 200°C to 400°C, then hydrating the aluminum oxide constituting the oxide layer to form a hydrated oxide layer containing hydrated aluminum oxide on the oxide layer, and finally forming the transparent film on the hydrated oxide layer. The method for manufacturing the aluminum member will be described in more detail below.

[0032] In manufacturing the aforementioned aluminum component, first, a base material made of aluminum or an aluminum alloy is prepared. The method for manufacturing the base material is not particularly limited, and known methods can be employed. For example, the base material may be manufactured by a method that appropriately combines casting, rolling, and heat treatment. As for the casting method of the base material, either DC casting or continuous casting may be employed. Furthermore, the base material may be formed into a desired shape by machining a cast material, forged material, or wrought material.

[0033] Furthermore, in the above manufacturing method, pretreatments such as degreasing, etching, desmatting, polishing, and grinding may be performed on the base material before anodizing, as necessary.

[0034] In the above manufacturing method, an oxide layer is formed on the base material by subjecting the base material prepared in this manner to an anodic oxidation treatment. In the anodic oxidation treatment, an oxide layer can be formed on the surface of the base material by DC electrolysis, that is, by passing a DC current between the base material and the counter electrode while the base material and the counter electrode are immersed in an electrolyte solution. The oxide layer formed in this way is composed of an aluminum oxide such as alumina and has a large number of pores.

[0035] The electrolyte used in the anodic oxidation process may be an acidic electrolyte containing electrolytes such as sulfuric acid, oxalic acid, or phosphoric acid, or an alkaline electrolyte containing electrolytes such as sodium metaborate. Preferably, the electrolyte used in the anodic oxidation process contains an inorganic electrolyte consisting of inorganic cations such as metal ions or ammonium ions, and one or more anions selected from the group consisting of sulfate ions, phosphate ions, and borate ions. By performing the anodic oxidation process using an electrolyte containing an inorganic electrolyte, an oxide layer having a desired structure can be formed more easily.

[0036] The current density of the DC current in the anodizing process is, for example, 1 mA / cm². ２ 100mA / cm or more ２ The following ranges can be used to set the temperature as appropriate. Furthermore, the electrolyte temperature in the anodizing process can be set as appropriate, for example, within the range of 0°C to 40°C.

[0037] If the oxide layer having pores is formed in the anodic oxidation process, the oxide layer may be dyed between heating the oxide layer and forming the hydrated oxide layer. In this case, an aluminum component exhibiting a chromatic color and excellent design can be obtained. The method for dyeing the oxide layer is not particularly limited, and an appropriate method can be adopted from known methods. Furthermore, as the dyeing agent used for dyeing, a dyeing agent selected from known dyeing agents such as dyes and pigments according to the desired color tone can be used.

[0038] In the above manufacturing method, after anodizing, the base material and the oxide layer are heated at a temperature of 200°C to 400°C. By heating the oxide layer at a temperature within the specified range before forming the hydrated oxide layer on the oxide layer, the internal stress of the oxide layer can be relaxed. Then, by forming the hydrated oxide layer after relaxing the internal stress of the oxide layer, the heat resistance of the oxide layer and the hydrated oxide layer can be improved. As a result, even when the temperature of the aluminum member rises, the occurrence of cracks in the oxide layer and the hydrated oxide layer can be suppressed.

[0039] From the viewpoint of more surely obtaining such an effect, in the manufacturing method, it is preferable that the oxide layer formed by an anodic oxidation treatment and the structure of the oxide layer at the time of starting heating are substantially the same. In other words, after forming the oxide layer by an anodic oxidation treatment, it is preferable to heat the oxide layer without performing a treatment for changing the structure of the oxide layer. From a similar viewpoint, it is more preferable to heat the oxide layer without performing other treatments after forming the oxide layer by an anodic oxidation treatment. Treatments for changing the structure of the oxide layer include, for example, a treatment for forming cracks in the oxide layer, a treatment for changing the pore diameter of pores in the oxide layer, and the like.

[0040] When the heating temperature of the oxide layer is less than 200°C, relaxation of the internal stress of the oxide layer becomes insufficient, and when the temperature of the aluminum member rises, cracks are likely to occur in the oxide layer and the hydrated oxide layer. By setting the heating temperature of the oxide layer to 200°C or higher, preferably 210°C or higher, more preferably 220°C or higher, still more preferably 230°C or higher, and particularly preferably 240°C or higher, generation of cracks can be suppressed even when the temperature of the aluminum member rises, and deterioration of the appearance of the aluminum member can be easily avoided.

[0041] On the other hand, when the heating temperature of the oxide layer exceeds 400°C, the oxide layer cannot follow the thermal expansion of the base material, and there is a possibility that cracks will occur in the oxide layer while the oxide layer is being heated. By setting the heating temperature of the oxide layer to 400°C or lower, preferably 380°C or lower, more preferably 350°C or lower, still more preferably 330°C or lower, and particularly preferably 300°C or lower, generation of cracks in the oxide layer during heating can be easily avoided, and an oxide layer having no cracks can be easily formed. Further, after forming an oxide layer having no cracks on the base material, by bringing the oxide layer into contact with a sealing agent, a hydrated oxide layer having no cracks can be easily formed.

[0042] In determining the preferable range of the heating temperature of the oxide layer, the upper and lower limits of the heating temperature of the oxide layer described above can be arbitrarily combined. For example, the heating temperature of the oxide layer may be 210°C or higher and 380°C or lower, may be 220°C or higher and 350°C or lower, may be 230°C or higher and 330°C or lower, or may be 240°C or higher and 300°C or lower.

[0043] In heating the oxide layer, heating may be terminated immediately after the temperature of the oxide layer reaches the desired temperature, or the temperature may be maintained for a certain period of time after reaching the desired temperature. From the viewpoint of sufficiently relaxing the internal stress of the oxide layer and more reliably obtaining an aluminum member in which cracks are less likely to occur in the oxide layer and the hydrated oxide layer even at high temperatures, the heating time from the start to the end of heating the oxide layer is preferably 1 minute or longer.

[0044] In the manufacturing method, after heating the oxide layer at a temperature within the specific range, a hydrated oxide layer is formed on the oxide layer. In forming the hydrated oxide layer, a substance capable of reacting with the aluminum oxide to form a hydrated oxide may be brought into contact with the oxide layer to hydrate the aluminum oxide contained in the oxide layer. Examples of such substances include warm water having a temperature of 80°C or higher, water vapor, and an aqueous solution containing ions of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir and Sc.

[0045] When warm water or water vapor is brought into contact with the oxide layer, a hydrated oxide layer composed of aluminum hydrated oxide can be formed on the oxide layer.

[0046] Furthermore, when an aqueous solution containing ions of the metal element is brought into contact with the oxide layer, a hydrated oxide layer can be formed on the oxide layer, comprising hydrated aluminum oxide and oxides and / or hydroxides of the metal element. The metal element may exist as a metal ion or as a complex ion in the aqueous solution. More specifically, as a sealing agent, aqueous solutions of metal salts containing the metal element, such as aqueous nickel acetate solution, aqueous cobalt acetate solution, aqueous nickel fluoride solution, aqueous chromate solution, and aqueous silicate solution, can be used.

[0047] In the above manufacturing method, a transparent film is formed on the hydrated oxide layer after the hydrated oxide layer has been formed. The method for forming the transparent film is not particularly limited, and known methods can be appropriately selected and adopted.

[0048] For example, when forming a transparent film, a method can be employed in which a coating agent is applied to a hydrated oxide layer and then heated. In this case, the coating agent only needs to be configured to form a transparent film after heating. The coating agent may also be colored with a chromatic color to the extent that it does not impair the transparency of the transparent film.

[0049] The method of applying the coating agent is not particularly limited, and the coating agent can be applied using known application devices such as bar coaters, roll coaters, and spray coaters. Furthermore, the thickness of the coating agent when applied can be appropriately set according to the desired thickness of the transparent film.

[0050] In the above manufacturing method, it is preferable to apply the coating agent and then heat and bake the coating agent under conditions where the maximum temperature reached by the base material is 100°C or higher and below the heating temperature of the oxide layer. As mentioned above, the oxide layer and hydrated oxide layer formed by conventional methods have low heat resistance, which has the problem of being prone to cracking due to heating during baking.

[0051] In contrast, in the above manufacturing method, since the oxide layer is heated within the specified temperature range, crack formation in these layers can be suppressed even when the temperature of the oxide layer and the hydrated oxide layer rises. Therefore, according to the above manufacturing method, the coating agent can be baked at a relatively high temperature without impairing the appearance of the aluminum member. Furthermore, by increasing the heating temperature during the baking of the coating agent, the durability of the transparent film can be further enhanced. Moreover, by increasing the heating temperature during the baking of the coating agent, the heating time can be shortened, and the productivity of the aluminum member can be increased.

[0052] From the viewpoint of further improving the durability of the transparent coating, the maximum temperature reached by the base material during baking is more preferably 120°C or higher, even more preferably 140°C or higher, and particularly preferably 160°C or higher.

[0053] On the other hand, from the viewpoint of suppressing the occurrence of cracks in the oxide layer and hydrated oxide layer and avoiding deterioration of the transparent film, the maximum temperature reached by the base material during baking is preferably 300°C or lower, more preferably 280°C or lower, and even more preferably 260°C or lower.

[0054] In determining the preferred range for the maximum temperature reached by the base material during baking, the upper and lower limits of the maximum temperature reached by the base material described above can be arbitrarily combined. For example, the preferred range for the maximum temperature reached by the base material during baking may be 100°C to 300°C, 120°C to 300°C, 140°C to 280°C, or 160°C to 260°C.

[0055] The reason why the aforementioned effects are obtained by keeping the maximum temperature of the base material during baking below the heating temperature of the oxide layer is not entirely clear, but the following reasons are possible. Multiple strains exist in the oxide layer formed on the base material, and these strains are thought to be released when heated to a temperature corresponding to the state of each strain. Therefore, when the oxide layer is heated in the manufacturing method of the aluminum member, it is thought that the strains present in the oxide layer are released according to the heating temperature of the oxide layer, and the internal stress is relieved. Consequently, when the maximum temperature of the base material during baking is below the heating temperature of the oxide layer, it is thought that there are no strains to be released within the oxide layer. For the reasons above, it is thought that the occurrence of cracks associated with the release of strains within the oxide layer can be suppressed by keeping the maximum temperature of the base material during baking below the heating temperature of the oxide layer.

[0056] During the baking process, heating may be terminated immediately after the base material reaches the desired maximum temperature, or the desired temperature may be maintained for a certain period of time after it has been reached.

[0057] As a coating agent, for example, an inorganic coating agent mainly composed of hydrolyzable silicon compounds such as alkoxysilanes, siloxanes, and silazanes can be used. By heating such a coating agent, an inorganic transparent film mainly composed of silicon dioxide can be formed on the hydrated oxide layer.

[0058] Furthermore, organic coating agents mainly composed of resins such as acrylic resin, methacrylic resin, polyester resin, epoxy resin, polyurethane resin, polyolefin resin, and polysulfone resin can also be used as coating agents. Additives such as silicone resin may be added to the organic coating agent as needed. By heating such a coating agent, an organic transparent film containing the organic resin can be formed on the hydrated oxide layer.

[0059] The coating agent preferably contains an organic resin. A coating agent containing an organic resin can form a highly durable transparent film by applying the coating agent to a hydrated oxide layer and then baking it. However, the oxide layer and hydrated oxide layer formed by conventional methods have low heat resistance and are prone to cracking due to heating during baking.

[0060] In contrast, in the above manufacturing method, since the oxide layer is heated within the specified temperature range, crack formation in these layers can be suppressed even when the temperature of the oxide layer and the hydrated oxide layer rises. Therefore, according to the above manufacturing method, even when using a coating agent containing an organic resin, which was previously difficult to bake at high temperatures, the coating agent can be baked at high temperatures without damaging the appearance of the aluminum component. Furthermore, by increasing the heating temperature during the baking of the coating agent, the durability of the transparent film can be further enhanced. Moreover, by increasing the heating temperature during the baking of the coating agent, the heating time can be shortened, and the productivity of the aluminum component can be increased.

[0061] (Example 1) An example of the method for manufacturing the aluminum member will be described with reference to Figures 1 to 5. As shown in Figure 1, the aluminum member 1 has a base material 2 made of aluminum or an aluminum alloy, an oxide layer 3 made of aluminum oxide formed on the base material 2, a hydrated oxide layer 4 containing hydrated aluminum oxide formed on the oxide layer 3, and a transparent film 5 formed on the hydrated oxide layer 4. Furthermore, the oxide layer 3 and the hydrated oxide layer 4 do not have cracks after being heated at a temperature of 200°C for 30 minutes.

[0062] In manufacturing the aluminum component 1 in this example, first, as shown in Figure 2, an oxide layer 3 made of aluminum oxide is formed on the base material 2 by anodizing the base material 2, which is made of aluminum or an aluminum alloy. This oxide layer 3 is heated at a temperature of 200°C to 400°C. Then, the aluminum oxide constituting the oxide layer 3 is hydrated to form a hydrated oxide layer 4 on the oxide layer 3, as shown in Figure 3. After that, a transparent film 5 can be formed on the hydrated oxide layer 4.

[0063] Table 1 shows specific examples (test materials A1 to A17) of the aluminum member 1 obtained by the manufacturing method of this example. The method for preparing these test materials is as follows, for example.

[0064] [Test Material A1] In manufacturing test material A1, first, an aluminum plate with a thickness of 1 mm and having a chemical composition represented by alloy number A5052 is prepared as the base material 2. This base material 2 is subjected to a pretreatment for anodic oxidation. Specifically, as a pretreatment, the base material 2 is first subjected to an alkaline etching treatment by immersing it in a sodium hydroxide aqueous solution with a concentration of 5 mass% at a temperature of 55°C. After that, the base material 2 is subjected to a desmatt treatment by immersing it in nitric acid with a concentration of 30 mass%.

[0065] After pre-treating the base material 2 as described above, DC electrolysis is performed on the base material 2 as an anodizing treatment to form an oxide layer 3 on the surface of the base material 2. The electrolyte used in the anodizing treatment is a 5% by mass aqueous sulfuric acid solution, the electrolyte temperature is 20°C, the treatment time is 60 minutes, and the current density is 10 mA / cm². 2 The oxide layer 3 formed in this manner is a so-called porous anodized film, and as shown in Figure 2, it has a large number of pores 31. The thickness of the oxide layer formed under these conditions is approximately 15 μm.

[0066] After anodizing, the base material 2 is heated in a heating furnace to relieve the internal stress of the oxide layer 3. The set temperature of the heating furnace is the value shown in the "Heating Temperature" column of Table 1, and the time the base material 2 stays in the furnace, that is, the time from the start of heating to the end of heating, is the value shown in the "Heating Time" column of Table 1.

[0067] Subsequently, the base material 2 equipped with the oxide layer 3 is immersed in hot water at 100°C for 30 minutes as a sealing agent, thereby forming a hydrated oxide layer 4 made of hydrated aluminum oxide on the oxide layer 3 as shown in Figure 3, and sealing the pores 31 of the oxide layer 3 with the hydrated oxide layer 4.

[0068] After forming the hydrated oxide layer 4, a coating agent containing an epoxy compound as the main component and an amino resin as the curing agent is applied to the hydrated oxide layer 4. Then, the base material 2 to which the coating agent has been applied is heated at 100°C for 30 minutes to bake it, thereby forming a transparent film 5 made of epoxy resin with the thickness shown in Table 1 on the hydrated oxide layer 4. Test material A1 can be obtained by the above procedure. The oxide layer 3 and the hydrated oxide layer 4 in test material A1 do not have cracks.

[0069] [Test materials A2 to A3] These test materials have a configuration that is generally the same as that of test material A1, except that the thickness of the transparent film 5 is changed to the value shown in Table 1. The method for preparing test materials A2 to A3 is the same as that for test material A1, except that the heating temperature of the oxide layer 3 is changed to the temperature shown in Table 1, the thickness of the transparent film 5 is changed as shown in Table 1, and the coating agent is heated under conditions that the maximum temperature reached by the base material 2 (i.e., PMT) is either 180°C or 220°C during the baking of the coating agent. The oxide layer 3 and hydrated oxide layer 4 in test materials A2 to A3 do not have cracks.

[0070] [Test Material A4] Test material A4 has a configuration that is generally the same as that of test material A1. The method for preparing test material A4 is the same as that for preparing test material A1, except that the coating agent is heated under conditions that the maximum temperature (i.e., PMT) of the base material 2 reaches 240°C during the baking of the coating agent. The oxide layer 3 and the hydrated oxide layer 4 in test material A4 do not have cracks.

[0071] [Test Material A5] Test Material A5 has a structure that is generally the same as Test Material A2, except that the oxide layer 3 is dyed blue. The method for preparing Test Material A5 is the same as the method for preparing Test Material A2, except that the oxide layer 3 is dyed between heating the oxide layer 3 and forming the hydrated oxide layer 4. The oxide layer 3 is dyed by immersing it in an aqueous solution of blue dye (TAC-blue, manufactured by Okuno Pharmaceutical Co., Ltd.). The concentration of the blue dye in the aqueous solution is 2 g / L, the temperature of the aqueous solution is 55°C, and the immersion time is 5 minutes. The oxide layer 3 and hydrated oxide layer 4 in Test Material A5 do not have cracks.

[0072] [Test Material A6] Test material A6 has a structure that is generally the same as test material A3, except that the oxide layer 3 is dyed blue. The method for preparing test material A6 is the same as the method for preparing test material A5, except that heating is performed under the same conditions as test material A3 when baking the coating agent. The oxide layer 3 and hydrated oxide layer 4 in test material A6 do not have cracks.

[0073] [Test materials A7-A8] These test materials have a configuration that is generally the same as test material A1, except that they have a transparent film 5 containing polyester resin, and the thickness of the transparent film 5 is as shown in Table 1. The method for preparing test materials A7-A8 is the same as the method for preparing test material A1, except that a coating agent containing polyester resin as the main component and melamine resin as the curing agent is used, the thickness of the transparent film 5 is changed as shown in Table 1, and heating is performed at a temperature of 80°C or 100°C for 30 minutes during the baking of the coating agent. The oxide layer 3 and hydrated oxide layer 4 in test materials A7-A8 do not have cracks.

[0074] [Test materials A9 to A11] These test materials have a configuration that is generally the same as that of test materials A7 to A8, except that the thickness of the transparent film 5 is as shown in Table 1. The method for preparing test materials A9 to A11 is the same as that for test materials A7 to A8, except that the thickness of the transparent film 5 is changed as shown in Table 1, and the coating agent is heated under conditions during baking so that the maximum temperature reached by the base material 2 is either 180°C or 240°C. The oxide layer 3 and hydrated oxide layer 4 in test materials A9 to A11 do not have cracks.

[0075] [Test materials A12 to A13] These test materials have a configuration that is generally the same as that of test material A1, except that they have a transparent film 5 containing polypropylene resin, and the thickness of the transparent film 5 is as shown in Table 1. The method for preparing test materials A12 to A13 is the same as the method for preparing test material A1, except that a coating agent containing polypropylene resin as the main component is used, the thickness of the transparent film 5 is changed as shown in Table 1, and when baking the coating agent, either the condition of heating at a temperature of 100°C for 30 minutes or the condition of heating so that the maximum temperature reached by the base material 2 is 200°C is adopted. The oxide layer 3 and hydrated oxide layer 4 in test materials A12 to A13 do not have cracks.

[0076] [Test materials A14 to A17] These test materials have a configuration that is generally the same as that of test material A1, except that they have a transparent film 5 containing acrylic resin, and the thickness of the transparent film 5 is as shown in Table 1. The method for preparing test materials A14 to A17 is the same as the method for preparing test material A1, except that a coating agent containing acrylic resin as the main component and a curing agent for acrylic resin is used, the thickness of the transparent film 5 is changed as shown in Table 1, and one of the following conditions is adopted during the baking of the coating agent: heating at a temperature of 80°C for 30 minutes, heating at a temperature of 120°C for 20 minutes, or the maximum temperature reached by the base material 2 is 240°C. The oxide layer 3 and hydrated oxide layer 4 in test materials A14 to A17 do not have cracks.

[0077] [Test materials B1 to B4] Test materials B1 to B4 are test materials for comparison with test materials A2 to A3. The method for preparing test material B1 is the same as the method for preparing test material A2, except that a hydrated oxide layer is formed without heating after the oxide layer is formed. The method for preparing test material B2 is the same as the method for preparing test material A3, except that a hydrated oxide layer is formed without heating after the oxide layer is formed. The method for preparing test material B3 is the same as the method for preparing test material A2, except that the heating temperature of oxide layer 3 is changed as shown in Table 1. The method for preparing test material B4 is the same as the method for preparing test material A3, except that the heating temperature of oxide layer 3 is changed as shown in Table 1.

[0078] [Test materials B5-B6] Test materials B5-B6 are test materials for comparison with test materials A5-A6. The method for preparing test material B5 is the same as that for test material A5, except that a hydrated oxide layer is formed without heating after the oxide layer is formed. The method for preparing test material B6 is the same as that for test material A6, except that a hydrated oxide layer is formed without heating after the oxide layer is formed.

[0079] [Test Material B7] Test material B7 is a test material for comparison with test materials A7 to A11. The method for preparing test material B7 is the same as that for test material A7, except that after forming the oxide layer, a hydrated oxide layer is formed without heating.

[0080] [Test Material B8] Test material B8 is a test material for comparison with test materials A14 to A17. The method for preparing test material B8 is the same as that for test material A14, except that after forming the oxide layer, a hydrated oxide layer is formed without heating.

[0081] The appearance of the test material obtained as described above is observed with a 35x magnification optical microscope, and magnified photographs are taken. The evaluation results for the presence or absence of cracks based on these magnified photographs are shown in the "Presence or Absence of Cracks" column of Table 1, under "After Baking of Transparent Coating".

[0082] Furthermore, after heating the test material at 200°C for 30 minutes, the appearance of the test material is observed with a 35x magnification optical microscope, and magnified photographs are obtained. The evaluation results for the presence or absence of cracks based on these magnified photographs are shown in the "After Heating" column under "Presence or Absence of Cracks" in Table 1. As an example, Figure 4 shows a magnified photograph of test material A10 after heating at 200°C for 30 minutes. Also, Figure 5 shows a magnified photograph of test material B7 after heating at 200°C for 30 minutes.

[0083]

[0084] As shown in Table 1, in the method for producing test materials A1 to A17, the oxide layer 3 is heated within the specified temperature range before the hydrated oxide layer 4 is formed. Therefore, as shown in Figure 4 as an example, even when each test material is heated at 200°C for 30 minutes, the occurrence of cracks in the oxide layer 3 and the hydrated oxide layer 4 can be suppressed. Furthermore, test materials A1 to A17, having these characteristics, are less prone to cracking in the oxide layer 3 and the hydrated oxide layer 4 even when their temperature rises, and can maintain a good appearance.

[0085] In contrast, in the manufacturing methods for test materials B1, B2, B5, and B6, the hydrated oxide layer is formed without heating the oxide layer. Therefore, as shown in Table 1, when baking the transparent film at a relatively high temperature, cracks are likely to occur in the oxide layer 3 and the hydrated oxide layer 4 during baking.

[0086] Furthermore, in the method for preparing test materials B3 to B4, the heating temperature during the baking of the transparent film is higher than the heating temperature of the oxide layer, which is within the specified range. Therefore, as shown in Table 1, when baking the transparent film at a relatively high temperature, cracks are likely to occur in the oxide layer 3 and the hydrated oxide layer 4 during baking.

[0087] In the method for preparing test materials B7 to B8, the transparent coating is baked at a relatively low temperature, which suppresses the occurrence of cracks during the baking of the transparent coating. However, since the oxide layer 3 is not heated before the formation of the hydrated oxide layer 4, cracks C tend to occur in the oxide layer 3 and the hydrated oxide layer 4 after heating at 200°C for 30 minutes, as shown in Figure 5.

[0088] (Example 2) In this example, the durability of a transparent film containing epoxy resin and a transparent film containing polyester resin is evaluated based on the amount of methyl ethyl ketone extract contained in the transparent film. The method for measuring the amount of methyl ethyl ketone extract in this example is as follows.

[0089] First, test specimens are prepared by cutting the test material shown in Table 2 to the specified dimensions. The mass (in grams) of these test specimens is accurately weighed to four decimal places, and then immersed in boiling methyl ethyl ketone for 60 minutes. After that, the test specimens removed from the methyl ethyl ketone are dried in a 100°C oven for 15 minutes. The mass (in grams) after drying is then accurately weighed to four decimal places.

[0090] The difference (in mg) between the mass before immersion in methyl ethyl ketone and the mass after immersion in methyl ethyl ketone, obtained in this way, is measured by the surface area (in cm²) of the transparent film. 2 By dividing by ), the amount of methyl ethyl ketone extract contained in the transparent film (unit: mg / cm³) can be calculated. 2 The amount of methyl ethyl ketone extract contained in the transparent coating of test materials A1, A4, A8, A9, and A11 is calculated. Table 2 shows the amount of methyl ethyl ketone extract contained in the transparent coating of test materials A1, A4, A8, A9, and A11.

[0091]

[0092] As shown in Table 2, the amount of methyl ethyl ketone extract in test materials A4, A9, and A11, which were baked under conditions where the maximum temperature reached by the base material was 180°C or higher, was less than the amount of methyl ethyl ketone extract in test materials A1 and A8, which were baked at a heating temperature of 100°C. Therefore, the transparent coatings of test materials A4, A9, and A11 have superior durability.

[0093] (Example 3) In this example, the durability of a transparent film containing polypropylene resin is evaluated based on the scratch hardness of the transparent film. Table 3 shows the scratch hardness of the transparent film measured according to the method in accordance with JIS K5600-5-4:1999.

[0094]

[0095] As shown in Table 3, the scratch hardness of test material A13, which was baked under conditions where the maximum temperature reached of the base material was 200°C, is higher than that of test material A12, which was baked at a heating temperature of 100°C. Therefore, the transparent coating of test material A13 has superior durability.

[0096] Although embodiments of the aluminum member and its manufacturing method have been described above based on Examples 1 to 3, the specific embodiments of the aluminum member, its manufacturing method and container according to the present invention are not limited to those of the examples, and the configuration can be appropriately modified without impairing the spirit of the present invention.

[0097] For example, the aluminum member may take the following forms [1] to [6].

[0098] [1] An aluminum member comprising: a base material made of aluminum or an aluminum alloy; an oxide layer made of aluminum oxide formed on the base material; a hydrated oxide layer containing hydrated aluminum oxide formed on the oxide layer; and a transparent film formed on the hydrated oxide layer, wherein no cracks are formed in the oxide layer and the hydrated oxide layer when the aluminum member is heated at a temperature of 200°C for 30 minutes.

[0099] [2] The aluminum member according to [1], wherein the thickness of the transparent film is 0.1 μm or more and 50 μm or less. [3] The aluminum member according to [1] or [2], wherein the transparent film contains an organic resin. [4] The organic resin is a polyester resin or an epoxy resin, and the mass loss after immersing the transparent film in boiling methyl ethyl ketone for 60 minutes is 1 mg / cm². 2 The following is the aluminum member described in [3].

[0100] [5] The aluminum member according to [3], wherein the organic resin is a polypropylene resin and the scratch hardness of the transparent film is H or higher. [6] The aluminum member according to any one of [1] to [5], wherein the hydrated oxide layer further comprises an oxide and / or hydroxide of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc.

[0101] Furthermore, the container may take the form described in [7] below: A container made of an aluminum member as described in any one of [7] [1] to [6].

[0102] Furthermore, the method for manufacturing the aluminum member may take the following forms [8] to

[13] .

[0103] [8] A method for manufacturing an aluminum member, comprising: applying an anodizing treatment to a base material made of aluminum or an aluminum alloy to form an oxide layer made of aluminum oxide on the base material; heating the oxide layer at a temperature of 200°C to 400°C; then hydrating the aluminum oxide constituting the oxide layer to form a hydrated oxide layer containing hydrated aluminum oxide on the oxide layer; and forming a transparent film on the hydrated oxide layer.

[0104] [9] The method for manufacturing an aluminum member according to [8], wherein, in forming the transparent film, a coating agent is applied to the hydrated oxide layer, and then the coating agent is heated and baked under conditions that the maximum temperature reached by the base material is 100°C or higher and less than or equal to the heating temperature of the oxide layer.

[10] The method for manufacturing an aluminum member according to [8] or [9], wherein, in forming the hydrated oxide layer, the oxide layer is brought into contact with hot water having a temperature of 80°C or higher, steam, or an aqueous solution containing ions of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc, thereby hydrating the aluminum oxide constituting the oxide layer.

[0105]

[11] The method for manufacturing an aluminum member according to any one of [8] to

[10] , wherein the thickness of the transparent film is 0.1 μm or more and 50 μm or less.

[12] The method for manufacturing an aluminum member according to any one of [8] to

[11] , wherein the oxide layer having pores is formed in the anodizing treatment, and the oxide layer is dyed between heating the oxide layer and forming the hydrated oxide layer.

[13] The method for manufacturing an aluminum member according to any one of [8] to

[12] , wherein the transparent film contains an organic resin.

Claims

1. An aluminum member comprising: a base material made of aluminum or an aluminum alloy; an oxide layer made of aluminum oxide formed on the base material; a hydrated oxide layer containing hydrated aluminum oxide formed on the oxide layer; and a transparent film formed on the hydrated oxide layer, wherein no cracks are formed in the oxide layer and the hydrated oxide layer when the aluminum member is heated at a temperature of 200°C for 30 minutes.

2. The aluminum member according to claim 1, wherein the thickness of the transparent film is 0.1 μm or more and 50 μm or less.

3. The aluminum member according to claim 1, wherein the transparent film contains an organic resin.

4. If the organic resin is a polyester resin or epoxy resin, the mass loss after immersing the transparent film in boiling methyl ethyl ketone for 60 minutes is 1 mg / cm². 2 The aluminum member according to claim 3, which is as follows:

5. The aluminum member according to claim 3, wherein the organic resin is a polypropylene resin and the scratch hardness of the transparent film is H or higher.

6. The aluminum member according to claim 1, wherein the hydrated oxide layer further comprises an oxide and / or hydroxide of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc.

7. A container made of an aluminum member according to any one of claims 1 to 6.

8. A method for manufacturing an aluminum component, comprising: applying an anodizing treatment to a base material made of aluminum or an aluminum alloy to form an oxide layer made of aluminum oxide on the base material; heating the oxide layer at a temperature of 200°C to 400°C; then hydrating the aluminum oxide constituting the oxide layer to form a hydrated oxide layer containing hydrated aluminum oxide on the oxide layer; and forming a transparent film on the hydrated oxide layer.

9. The method for manufacturing an aluminum member according to claim 8, wherein, in forming the transparent film, after applying the coating agent to the hydrated oxide layer, the coating agent is heated and baked under conditions that the maximum temperature reached by the base material is 100°C or higher and less than or equal to the heating temperature of the oxide layer.

10. A method for producing an aluminum member according to claim 8 or 9, wherein, in forming the hydrated oxide layer, the aluminum oxide constituting the oxide layer is hydrated by contacting the oxide layer with hot water having a temperature of 80°C or higher, steam, or an aqueous solution containing ions of one or more metal elements selected from the group consisting of Ni, Cr, Zr, Si, Ti, Au, Ag, Co, Mo, Mn, Nb, Ta, W, Zn, Fe, Ir, and Sc.

11. The method for manufacturing an aluminum member according to claim 8 or 9, wherein the thickness of the transparent film is 0.1 μm or more and 50 μm or less.

12. A method for manufacturing an aluminum member according to claim 8 or 9, wherein the oxide layer having pores is formed in the anodizing treatment, and the oxide layer is dyed between the time the oxide layer is heated and the time the hydrated oxide layer is formed.

13. The method for manufacturing an aluminum member according to claim 8 or 9, wherein the transparent film contains an organic resin.

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